harden: make the background physically unable to read the shared state singleton (closes #324)

Five defects traced to one fact: src/background/index.js read and wrote the
module-level `state` singleton in src/shared/state.js, which the MV3 service
worker never populates and which answered an unpopulated read out of
DEFAULT_STATE in silence. Every previous fix added a loadState() before the
access, and that is what produced the fifth: a load detaches the objects an
in-flight handler is holding.

So the reachability goes rather than a sixth call site.

The background now has its own storage layer, src/background/state.js:
getState() is a detached, normalized per-call read, and updateState() is a
queued read-modify-write whose read is one storage round trip ahead of its
write. Nothing in the background holds an in-memory copy of the profile.

- Every handler takes one snapshot and answers from it, including the address
  it names: activeAddressOf(s) replaced a second, later storage read that
  could disagree with the first.
- wallet_switchEthereumChain applies applyChainSwitchFields() (split out of
  chainSwitch.js, which keeps the singleton path for the popup) inside
  updateState() instead of calling onChainSwitch() on the singleton.
- The remembered site decision is a read-modify-write, not a load-mutate-save
  around a prompt the user takes seconds to answer.
- backgroundRefresh() refreshes a private copy of the wallets and applies the
  balances that came back by address, so it never publishes an object other
  in-flight work holds, and a wallet added or deleted during the round trip
  survives its write.
- The transaction attempt takes its chain id and its endpoint from the same
  snapshot. They used to come from different moments, so a chain switch
  committed in between moved the endpoint under an artifact already verified
  against the old chain.

getProvider(rpcUrl, networkId) now REQUIRES the network id and validates it
against networks.js. That closes the cold-worker wrong-chain send at its shape
rather than at one call site: the hint used to default to currentNetwork() off
the unpopulated singleton, so the endpoint was the user's chain and ethers
fixed chainId at 0x1, and the wallet's own verifySignedTx then refused every
non-mainnet dApp send. refreshBalances(), lookupTokenInfo(), scanForAddresses()
and resolveEnsName() carry the id through; balances.js no longer requires
state.js at all.

The prohibition is enforced mechanically, not by review, and it is enforced by
the bundler rather than by a guess at what the bundler does. build.js keeps a
FORBIDDEN_INPUTS table of modules an entry point's bundle may not contain, and
assertNoForbiddenInputs() fails the build when esbuild's metafile reports
src/shared/state.js as an input of a background bundle, naming the import chain
from the metafile's own graph. That is the resolution the shipped bundle was
built from, so no specifier syntax, no hop and no resolution rule can slip past
it; Dockerfile:42 runs make build, so it holds in CI. A FORBIDDEN_INPUTS key
that matches no bundled entry point also fails, so the table cannot rot into a
vacuous pass.

A custom ESLint rule walks the CommonJS require graph from every src/background/
file and reports the same thing in the editor, before a full bundle. It matches
specifiers textually, so it is best-effort fast feedback and not the guarantee —
two earlier revisions of it shipped holes (a template literal, a dynamic
import(), a comment inside the call, a directory resolved through package.json
main). Those are covered now and pinned by
tests/backgroundStateLintRule.test.js, and the next divergence between a
hand-rolled matcher and a real bundler is caught by the build instead. A
computed specifier (require("../shared/" + "state")) is deliberately not
matched: esbuild cannot resolve it either, so it never reaches the bundle.

Reading a persisted field of the singleton before any load now throws
StateNotLoadedError instead of serving DEFAULT_STATE.

Test stubs: chrome.storage.local is a serialization boundary, and eight files
stubbed it with an aliasing get, so the object a module held and the object
"storage" held were one object — an assertion could pass on a build that never
wrote anything. Every test that drives real persistence now goes through
tests/support/storageStub.js, which structured-clones in both directions.

closes #320

.dockerignore

@@ -4,3 +4,4 @@
 node_modules
 .DS_Store
 dist
+release

.gitignore

@@ -23,6 +23,9 @@ node_modules/
 # Build output
 dist/
 
+# Release artifacts (make package). Derived from dist/, never committed.
+release/
+
 # Yarn
 .yarn-integrity
 package-lock.json

.prettierignore

@@ -1,4 +1,5 @@
 node_modules/
 yarn.lock
 dist/
+release/
 .claude/

Makefile

@@ -1,4 +1,4 @@
-.PHONY: bootstrap setup install test test-e2e test-e2e-firefox lint fmt fmt-check check check-censored docker hooks build build-debug vendor-blocklist clean dev
+.PHONY: bootstrap setup install test test-e2e test-e2e-firefox lint fmt fmt-check check check-censored docker hooks build build-debug package vendor-blocklist clean dev
 
 # Standard targets are thin shims; the implementations live in script/
 # per the scripts-to-rule-them-all pattern (see the Entrypoints section
@@ -41,6 +41,9 @@ check:
 check-censored:
 	@script/check-censored
 
+package:
+	@script/package
+
 docker:
 	@script/docker
 
@@ -102,7 +105,7 @@ vendor-blocklist:
 	@script/vendor-blocklist
 
 clean:
-	@rm -rf dist/
+	@rm -rf dist/ release/
 
 dev:
 	@echo "Building in watch mode..."

README.md

@@ -44,7 +44,107 @@ Load the extension:
 - **Chrome**: Navigate to `chrome://extensions/`, enable "Developer mode", click
   "Load unpacked", and select the `dist/chrome/` directory.
 - **Firefox**: Navigate to `about:debugging#/runtime/this-firefox`, click "Load
-  Temporary Add-on", and select `dist/firefox/manifest.json`.
+  Temporary Add-on", and select `dist/firefox/manifest.json`. Read
+  [Installing on Firefox](#installing-on-firefox) before relying on this: a
+  temporary add-on does not survive closing the browser.
+
+### Release Artifacts
+
+`make package` runs `make build` and then writes one self-contained, versioned
+archive per browser into `release/`, plus a `SHA256SUMS` for them:
+
+```bash
+make package
+```
+
+```
+release/autistmask-chrome-<version>.zip
+release/autistmask-firefox-<version>.xpi
+release/SHA256SUMS
+```
+
+Nothing is published by this. Tagging, CRX packing and any upload are
+outward-facing acts and are the owner's alone.
+
+The archives are deterministic — entries sorted, timestamps fixed, compression
+level fixed — so two builds of one commit produce byte-identical files and the
+recorded digest is a property of the input rather than of the clock.
+
+**Self-containment is checked, not assumed.** `build.js` writes the compiled
+Tailwind output to `dist/styles.css` at the `dist/` ROOT, outside both browser
+directories, and copies it into each of them as `src/popup/styles.css`; a naive
+`zip -r dist/chrome` is therefore correct only by accident. So the packager
+resolves every path referenced by the manifest and by every HTML document in the
+archive, requires each to be inside the archive, and fails on any reference that
+climbs out of the extension root. Files left at the `dist/` root are printed as
+deliberately not shipped rather than dropped by a glob. The archive is then read
+back off disk and compared member by member against the directory it was built
+from: an archive nobody opened is a claim, not an artifact.
+
+There is one version, and the build enforces it. `package.json`,
+`manifest/chrome.json` and `manifest/firefox.json` each declare one and none is
+derived from another — the manifests are copied to `dist/` verbatim, which is
+what `tests/manifest.test.js` asserts — so `script/lib/version.js` requires all
+three to agree and **fails the build when they do not**, naming each file and
+what it said. `tests/version.test.js` covers that rule in `make check`.
+
+### Installing on Chrome
+
+`manifest/chrome.json` carries a fixed `key`: the public half of an RSA keypair,
+base64-encoded DER. It exists for one reason. An unpacked Chrome extension with
+no `key` gets an extension id derived from the **absolute path it was loaded
+from**, and `chrome.storage.local` — which is where the wallet lives — is
+partitioned by that id. Move the checkout, re-clone it, or load a second copy
+from anywhere else, and the extension comes up on a fresh, empty storage
+partition: the wallet is simply gone, with no error and nothing in the UI to say
+so. With the `key` in place the id is derived from the key instead, and follows
+the extension wherever it is loaded from. That id is
+`gipbhkogfopeahplcjhipkgpcimdpkip`, pinned in `tests/extensionId.test.js` and
+observed against a real Chrome in `tests/e2e/storagePartition.js`.
+
+**Changing `key` changes the extension id, and orphans every wallet stored under
+the old one.** It is a migration, not an edit.
+
+The **private** half is a credential. It is not in this repository, no target
+generates one into the working tree, `*.pem` and `*.key` are gitignored, and
+`tests/extensionId.test.js` fails if such a file is ever committed. It is not
+needed to build, load or test anything here — it signs a CRX, and this repo does
+not pack one. A packer would take it from outside the repo, e.g.
+`chrome --pack-extension=dist/chrome --pack-extension-key=<path to the .pem>`.
+
+### Installing on Firefox
+
+**The XPI this repo produces is UNSIGNED, and release Firefox and Firefox ESR
+will refuse to install it.** Those builds enforce add-on signing with no working
+override — `xpinstall.signatures.required` does nothing on them — so a permanent
+install needs Firefox Developer Edition, Nightly, or an Unbranded build, with
+`xpinstall.signatures.required` set to `false` in `about:config`.
+
+Signing means submitting to AMO (self-distribution is enough, and does not
+require listing), which needs credentials this repository does not have and is
+the owner's decision.
+
+The other route is `about:debugging#/runtime/this-firefox` -> "Load Temporary
+Add-on", which works on every Firefox including release. **A temporary add-on is
+unloaded when Firefox exits**, so daily use means re-adding it by hand on every
+browser start.
+
+**The wallet survives the restart.** `manifest/firefox.json` declares a fixed
+`browser_specific_settings.gecko.id`, and Firefox keys the extension's storage
+area on that id rather than on the install, so adding the temporary add-on again
+in the same profile finds the vault where it left it. That is asserted, not
+assumed: `tests/e2e/firefox/reinstall.js` installs the packaged XPI in a real
+Firefox, creates a wallet through the UI, quits the browser, starts it again on
+the same profile, adds the add-on again, and decrypts the vault with the
+original password back to the original recovery phrase. The `moz-extension://`
+origin the popup is served from is _not_ stable across installs and does not
+need to be — nothing durable is keyed on it.
+
+**Removing the add-on does not.** An explicit uninstall — about:addons "Remove"
+— destroys the extension's storage, and the vault with it. That is ordinary,
+correct browser behaviour and it is observed in the same suite, but for a wallet
+it is worth saying out loud: **on Firefox, Remove is irreversible, and the
+recovery phrase is the only way back.**
 
 ### Debug Builds
 
@@ -146,6 +246,11 @@ provide:
   fails anywhere else. Part of `make check`, which inspects `dist/` when there
   is one and says loudly when there is not; `make build` re-runs it with
   `--require-dist`, so a build artifact is always covered
+- `script/package` — produce the release artifacts: `make build` first, so the
+  archives can only ever be made from a `dist/` that has been verified against
+  that build's own receipt as a RELEASE build, then one self-contained,
+  versioned archive per browser into `release/` (see
+  [Release Artifacts](#release-artifacts)). It packages and does not publish
 - `script/vendor-blocklist` — refresh `src/shared/phishingBlocklist.json` from
   its upstream, pinned to a commit and to the sha256 of the bytes that commit
   serves. Run deliberately, never as part of a build: the output is committed
@@ -198,7 +303,7 @@ The Makefile shims to those. It also carries a few targets that have no
 - `make build-debug` — the same build with `AUTISTMASK_DEBUG=1`, verified as a
   debug build, and keeping its `dist/` on failure (see
   [Debug Builds](#debug-builds))
-- `make clean` — remove `dist/`
+- `make clean` — remove `dist/` and `release/`
 - `make dev` — build in watch mode
 
 ## End-to-End Tests
@@ -334,6 +439,23 @@ class before a browser is involved, so this suite is no longer the only thing
 standing between it and a release — but a static rule only sees identifiers, and
 the runtime errors this suite catches are broader than one rule.
 
+`make test-e2e` then runs a second program in the same image,
+`tests/e2e/storagePartition.js`, which answers where `chrome.storage.local`
+lives. It loads the built extension from one temporary directory in a fresh
+profile, writes a sentinel key the extension itself never touches, closes the
+browser, and loads a **copy at a different path into the same profile** — then
+does it again with `key` stripped out of the manifest, and reports what each
+pair actually did rather than what it expected. It needs its own browser
+sessions, four of them, because the whole subject is what happens ACROSS loads.
+
+The observed behaviour, on the pinned Chromium: **with `key`, both paths get the
+same extension id and the second load reads the first load's storage. Without
+`key`, the two paths get different ids and the second load sees an empty
+partition** — the wallet, silently gone. Loading both keyed copies at once in
+one profile yields a single extension id, not two: Chrome does not load a second
+copy of an id it already has. The assertions are annotated as observations, so a
+Chrome that ever changes this fails the run instead of passing it.
+
 ### Firefox (`make test-e2e-firefox`)
 
 `make test-e2e-firefox` builds `dist/firefox/` and drives the **real popup in a
@@ -351,6 +473,33 @@ runner rather than believed from the extension, and the stub node has to answer
 `eth_sendRawTransaction` with the hash `ethers` computes for the artifact it
 sent, or `provider.broadcastTransaction()` refuses the answer.
 
+`make test-e2e-firefox` then runs a second program in the same image,
+`tests/e2e/firefox/reinstall.js`, and it installs the **packaged XPI** rather
+than the unpacked directory — the only place a real Firefox is asked to load the
+artifact that would actually be handed to someone. It runs two browsers over one
+profile, because it asks two questions that have different answers:
+
+- **Restart.** Install, create a wallet through the UI, record the vault, quit
+  the browser, start it again on the same profile, add the add-on again. The
+  extension must not come up as a fresh install; the vault, xpub and first
+  address must be unchanged; and the vault must still **decrypt** with the
+  original password to the original recovery phrase, through the real Show
+  Recovery Phrase screen. "The ciphertext is still in storage" and "the wallet
+  still works" are different claims and only the second one is worth anything.
+  This is what a user does every day, because a temporary add-on is unloaded
+  when Firefox exits.
+- **Removal.** Then, in the same browser, an explicit uninstall and a fresh
+  install. Observed: **Firefox destroys the extension's storage on uninstall**,
+  so the vault is gone. Recorded as an assertion, so a Firefox that ever changes
+  it fails the run, and stated in
+  [Installing on Firefox](#installing-on-firefox) because for a wallet it means
+  Remove is irreversible except from the recovery phrase.
+
+It also pins down something worth knowing about the harness: the
+`moz-extension://` uuid the popup is served from is not stable across installs,
+and navigating to a stale one does not fail — it hangs. The program reads the
+live uuid out of `extensions.webextensions.uuids` after every install.
+
 Both suites build their own image, each with the repo and a fresh extension
 build baked in; what differs is the base. The Chrome image layers those on top
 of a published Playwright image, whereas this one is assembled from a `node`
@@ -734,6 +883,25 @@ transaction detail view is the authoritative record and already shows exact
 precision. The 4-decimal rule is unchanged everywhere else, including for
 amounts at or above the floor on the approval screens.
 
+The floor applies only where the token's scale is known. Where it is not, the
+approval screen states base units instead of a quantity — see Unknown token
+scale below — and no truncation happens at all.
+
+**Specific Exception — unknown token scale:** Calldata carries base units and no
+scale, so every amount on the dApp approval screen needs the token's `decimals`.
+It is resolved from the bundled token list, then from the tokens the user
+tracks, then from what the block explorer reported for the contract
+(`resolveTokenDecimals()` in `src/shared/approvalAmount.js`). Where none of them
+answers, the amount is not formatted: the line reads
+`5000000000 base units (decimals unknown)`. A guessed scale is not an
+approximation but a different number — 1,000 units of a 6-decimal token
+formatted at 18 decimals reads `0.000000001` — on the screen whose only job is
+to state what is being authorized. Both amount paths of that screen take this
+rule: the ERC-20 `transfer`/`approve` line (`src/popup/views/approval.js`) and
+the swap's `Amount` and `Min. received` lines (`src/shared/uniswap.js`). An
+unbounded allowance or permit needs no scale to describe and is still shown as
+`Unlimited`.
+
 #### Partial USD totals
 
 Prices are fetched for the top 25 tokens only, so an address can hold assets the

TODO.md

@@ -45,6 +45,51 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-08-23: The background no longer reads or writes the shared `state`
+  singleton ([#324](https://git.eeqj.de/sneak/AutistMask/issues/324)), which
+  also closes the cold-worker wrong-chain send
+  ([#320](https://git.eeqj.de/sneak/AutistMask/issues/320)). One in-memory copy
+  loaded once is the popup's lifetime, not the MV3 worker's: the worker is
+  killed when idle, nothing loaded state at module scope, and an unpopulated
+  read was answered out of `DEFAULT_STATE` in silence. Five defects traced to
+  that, and every point fix added a `loadState()` that created the next one — a
+  load detaches the objects an in-flight handler is holding. The background now
+  has its own storage layer (`src/background/state.js`): `getState()` for a
+  detached per-call read, `updateState()` for a queued read-modify-write.
+  `backgroundRefresh()` refreshes a private copy and applies the balances that
+  came back by address, so a wallet added, renamed or deleted during the round
+  trip survives. The transaction attempt takes its chain id and its endpoint
+  from one snapshot, so a committed chain switch can no longer move the endpoint
+  under an artifact already verified against the old chain. `getProvider()` now
+  REQUIRES the network id, which is what closes
+  [#320](https://git.eeqj.de/sneak/AutistMask/issues/320) at the shape rather
+  than at the call site. The prohibition is enforced by `build.js`, which fails
+  the build when esbuild's own metafile reports `src/shared/state.js` as an
+  input of either background bundle — the resolution the shipped bundle was
+  actually built from, so no specifier syntax and no resolution rule can slip
+  past it, and `make build` runs in CI. An ESLint rule that walks the require
+  graph textually gives the same answer in the editor, before a full bundle; it
+  is fast feedback rather than the guarantee, and the shapes it is known to
+  catch are pinned by `tests/backgroundStateLintRule.test.js`. Reading an
+  unloaded singleton now throws `StateNotLoadedError` instead of serving
+  defaults. The `chrome.storage.local` stubs in eight test files aliased instead
+  of structured-cloning, which could let an assertion pass on a build that never
+  wrote anything; every test that drives real persistence now goes through
+  `tests/support/storageStub.js`.
+- 2026-08-23: The swap approval screen no longer guesses 18 decimals for a token
+  outside the bundled list
+  ([#340](https://git.eeqj.de/sneak/AutistMask/issues/340)). `tokenInfo()` in
+  `src/shared/uniswap.js` returned `decimals: 18` for any such token — the same
+  assumption [#306](https://git.eeqj.de/sneak/AutistMask/issues/306) removed
+  from the ERC-20 amount line — so a 1,000-unit swap of a 6-decimal token was
+  stated as `0.000000001`, and every newly listed token reached it. The swap's
+  `Amount` and `Min. received` lines now resolve the scale through
+  `resolveTokenDecimals()`, the same bundled-list-then-tracked-then-explorer
+  order the ERC-20 line uses, and where nothing knows it they render
+  `unknownDecimalsAmount()` — base units with the scale stated — instead of a
+  number. No new data source and no network call: the scale comes only from what
+  the wallet already holds. An unbounded permit is still shown as `Unlimited`.
+  `README.md` records the rule as a Display Consistency exception.
 - 2026-08-23: A failed release build no longer leaves a loadable debug bundle in
   `dist/` ([#333](https://git.eeqj.de/sneak/AutistMask/issues/333)). With
   `AUTISTMASK_DEBUG=1` exported, `make build` compiled a debug bundle and failed
@@ -84,6 +129,40 @@ but the review is broader than any of them.
   lists (`src/shared/transactions.js`) keep the unfloored rule, which is out of
   scope by the issue's definition of done. `README.md`'s Display Consistency
   section records the exception.
+- 2026-08-23: The extension can be installed once and kept
+  ([#310](https://git.eeqj.de/sneak/AutistMask/issues/310)). There was no
+  packaging target anywhere, no artifact, and `manifest/chrome.json` carried no
+  `key` — so an unpacked Chrome load derived its extension id, and therefore its
+  `chrome.storage.local` partition, from the absolute checkout path: moving or
+  re-cloning the checkout presented an empty wallet with no error. The manifest
+  now carries a fixed `key` (public half only; the private half is a credential
+  and is not in this repo, and no target generates one into the tree), pinning
+  the id to `gipbhkogfopeahplcjhipkgpcimdpkip`. `make package` produces
+  `release/autistmask-chrome-<version>.zip` and
+  `release/autistmask-firefox-<version>.xpi` plus `SHA256SUMS`,
+  deterministically and via `make build` so the archives can only be made from a
+  `dist/` already verified against that build's receipt as a release build;
+  every path the manifests and the popup HTML reference is resolved and required
+  to be inside the archive, and the archive is read back off disk and compared
+  member by member — `dist/styles.css` sits at the `dist/` root outside both
+  browser directories and is reported as deliberately not shipped rather than
+  dropped by a glob. One version: `script/lib/version.js` fails the build when
+  `package.json` and the two manifests disagree, instead of reading from one of
+  them. `BUILD_COMMIT` now carries `-dirty` when the working tree does not match
+  `HEAD` (and `-unknown` when git cannot say), while the full hash behind the
+  About screen's commit link stays clean so the link still resolves. Two real
+  browser observations back it: `tests/e2e/storagePartition.js` loads the
+  extension from two different paths in one Chrome profile with and without
+  `key` and records what each does, and `tests/e2e/firefox/reinstall.js`
+  installs the packaged XPI in a real Firefox, creates a wallet, restarts the
+  browser on the same profile, adds the add-on again and decrypts the vault back
+  to the original recovery phrase — and then observes that an explicit uninstall
+  DESTROYS that storage, which is correct browser behaviour but means Remove is
+  irreversible for a wallet, now stated in README.md. Deliberately not done: AMO
+  signing, CRX packing, tagging and any upload — the Firefox artifact is
+  UNSIGNED and README.md now states that release Firefox and ESR refuse it, that
+  Developer Edition or an Unbranded build is required, and that a temporary
+  add-on does not survive a browser restart.
 - 2026-08-20: A second extension page can no longer silently delete a wallet
   ([#304](https://git.eeqj.de/sneak/AutistMask/issues/304)). `saveState()` wrote
   the entire state blob, and every extension page — the toolbar popup, a dApp

build.js

@@ -3,6 +3,7 @@ const path = require("path");
 const crypto = require("crypto");
 const { execSync } = require("child_process");
 const esbuild = require("esbuild");
+const { resolveVersion } = require("./script/lib/version");
 
 const DIST = path.join(__dirname, "dist");
 const DIST_CHROME = path.join(DIST, "chrome");
@@ -15,6 +16,26 @@ const SRC = path.join(__dirname, "src");
 // rotting with it.
 const AUDITED_MODULE = "src/shared/constants.js";
 
+// Modules a given entry point's bundle may not contain, keyed by the
+// repo-relative entry point.
+//
+// src/shared/state.js is a module-level object loaded once by loadState() and
+// mutated in place from then on. That is the popup's model. The MV3 service
+// worker has no "once" — it is killed when idle and revived by the next
+// message — so a background read of it is answered out of DEFAULT_STATE. Five
+// defects came from that, one of which destroyed a wallet
+// (https://git.eeqj.de/sneak/AutistMask/issues/324); the background has its own
+// per-call storage layer in src/background/state.js instead.
+//
+// This is the authoritative check, and it is here rather than in the linter
+// because it consults the resolution esbuild actually performed. Any specifier
+// syntax, any hop, any resolution rule that puts the module in the bundle fails
+// the build, whether or not a text matcher would have recognized it.
+// Dockerfile:42 runs `make build`, so it is enforced in CI.
+const FORBIDDEN_INPUTS = {
+    "src/background/index.js": ["src/shared/state.js"],
+};
+
 // The build receipt: every file this build emits, with its sha256 and whether
 // it is one of the audited bundles. script/verify-build is handed this and
 // checks dist/ against it, so the file list comes from the build that just ran
@@ -64,6 +85,71 @@ function outputsContainingAuditedModule(metafile) {
         .map(([outFile]) => repoRelative(outFile));
 }
 
+// Shortest import chain from `entryInput` to `target` through the metafile's
+// own input graph, or null when there is none. The message this feeds is the
+// point of the check: "state.js is in the worker bundle" is not actionable on
+// its own, "index.js -> chainSwitchFields.js -> state.js" is.
+function importChain(metafile, entryInput, target) {
+    const graph = new Map(
+        Object.entries(metafile.inputs).map(([input, info]) => [
+            repoRelative(input),
+            (info.imports || []).map((i) => repoRelative(i.path)),
+        ]),
+    );
+    const start = repoRelative(entryInput);
+    const seen = new Set([start]);
+    const queue = [[start]];
+    while (queue.length > 0) {
+        const chain = queue.shift();
+        for (const next of graph.get(chain[chain.length - 1]) || []) {
+            if (next === target) return chain.concat([next]);
+            if (seen.has(next)) continue;
+            seen.add(next);
+            queue.push(chain.concat([next]));
+        }
+    }
+    return null;
+}
+
+// Entry points from FORBIDDEN_INPUTS that this build actually bundled. A key
+// that matches nothing means the table has rotted away from the entry point
+// list — the prohibition would then be silently unenforced, so the build fails
+// on it rather than passing vacuously.
+const forbiddenEntriesSeen = new Set();
+
+// Fail the build when an entry point's bundle contains a module it is
+// prohibited from reaching. The inputs come from esbuild's metafile, so this is
+// the resolution the shipped bundle was built from and not a guess at it.
+function assertNoForbiddenInputs(entryPoint, outfile, metafile) {
+    const entry = repoRelative(entryPoint);
+    const forbidden = FORBIDDEN_INPUTS[entry];
+    if (!forbidden) return;
+    forbiddenEntriesSeen.add(entry);
+
+    const out = repoRelative(outfile);
+    const entryOutput = Object.entries(metafile.outputs).find(
+        ([outFile]) => repoRelative(outFile) === out,
+    );
+    if (!entryOutput) {
+        throw new Error(`esbuild reported no metafile output for ${out}`);
+    }
+    const inputs = new Set(
+        Object.keys(entryOutput[1].inputs).map(repoRelative),
+    );
+
+    for (const module of forbidden) {
+        if (!inputs.has(module)) continue;
+        const chain = importChain(metafile, entryPoint, module);
+        throw new Error(
+            `${out} bundles ${module}, which ${entry} must not reach` +
+                `${chain ? `: ${chain.join(" -> ")}` : ""}. The MV3 worker ` +
+                `never populates the shared state singleton, so reading it ` +
+                `serves DEFAULT_STATE. Use getState()/updateState() from ` +
+                `src/background/state.js instead.`,
+        );
+    }
+}
+
 // Every file this build writes under dist/, recorded as it is written. This is
 // the build's own account of what it emitted; it is never recovered by
 // listing dist/, because a file that is in dist/ without this build having put
@@ -160,28 +246,53 @@ function isDebugBuild() {
     return process.env.AUTISTMASK_DEBUG === "1";
 }
 
+// A short git output, or null when git cannot answer. Distinguishing "git said
+// nothing" from "git could not be asked" matters below: a working tree whose
+// state is unknown must not be stamped as clean.
+function git(args) {
+    try {
+        return execSync(`git ${args}`, {
+            encoding: "utf8",
+            stdio: ["ignore", "pipe", "ignore"],
+        }).trim();
+    } catch {
+        // not a git repo, or git not available
+        return null;
+    }
+}
+
+// The working-tree state, as a suffix for the displayed commit: "" when the
+// tree matches HEAD, "-dirty" when it does not, "-unknown" when git answered
+// the hash but not the status. Without this a build from a modified tree
+// stamped a clean hash, so the About screen named a commit whose contents were
+// not what was running — the one thing that stamp exists to establish.
+//
+// git status --porcelain honours .gitignore, so dist/ and node_modules/ do not
+// make every build dirty; an untracked file that is NOT ignored does, and
+// correctly: it may well be in the bundle.
+function worktreeSuffix() {
+    const status = git("status --porcelain");
+    if (status === null) return "-unknown";
+    return status === "" ? "" : "-dirty";
+}
+
 function getBuildInfo() {
     const pkg = JSON.parse(
         fs.readFileSync(path.join(__dirname, "package.json"), "utf8"),
     );
-    let commitHash = "unknown";
-    try {
-        commitHash = execSync("git rev-parse --short HEAD", {
-            encoding: "utf8",
-        }).trim();
-    } catch {
-        // not a git repo or git not available
-    }
-    let commitHashFull = "unknown";
-    try {
-        commitHashFull = execSync("git rev-parse HEAD", {
-            encoding: "utf8",
-        }).trim();
-    } catch {
-        // not a git repo or git not available
-    }
+    const commitHashFull = git("rev-parse HEAD") || "unknown";
+    const shortHash = git("rev-parse --short HEAD") || "unknown";
+    // The full hash is left clean because it is the href of the commit link in
+    // the About screen, and "abc123-dirty" is not a commit anyone can fetch.
+    // The displayed short hash carries the marker, so the screen says the tree
+    // was modified while still linking somewhere real.
+    const commitHash =
+        shortHash === "unknown" ? shortHash : shortHash + worktreeSuffix();
     return {
-        version: pkg.version,
+        // Fails the build when package.json and the two manifests disagree;
+        // see script/lib/version.js. Called before anything is emitted, so a
+        // tree with no single version never reaches dist/.
+        version: resolveVersion(__dirname),
         license: pkg.license,
         author: pkg.author,
         commitHash,
@@ -267,6 +378,9 @@ async function build() {
             metafile: true,
             define,
         });
+        // Before the output is recorded as emitted: a bundle that violates a
+        // prohibition must abort the build, not be written into a receipt.
+        assertNoForbiddenInputs(entryPoint, outfile, result.metafile);
         recordEmitted(outfile);
         auditedBundles.push(...outputsContainingAuditedModule(result.metafile));
     }
@@ -323,6 +437,15 @@ async function build() {
         path.join(DIST_FIREFOX, "manifest.json"),
     );
 
+    for (const entry of Object.keys(FORBIDDEN_INPUTS)) {
+        if (!forbiddenEntriesSeen.has(entry)) {
+            throw new Error(
+                `${entry} is listed in FORBIDDEN_INPUTS but was not bundled, ` +
+                    `so nothing checked it`,
+            );
+        }
+    }
+
     // Written last so a build that died partway through leaves no receipt at
     // all, which script/verify-build treats as a hard failure rather than as
     // "nothing to check".

eslint.config.js

@@ -8,6 +8,7 @@
 
 const js = require("@eslint/js");
 const globals = require("globals");
+const backgroundState = require("./script/lib/eslint/noStateSingletonInBackground");
 
 // The extension APIs. MV3 Chrome exposes `chrome`; Firefox exposes both, and
 // the code feature-detects between them.
@@ -78,12 +79,28 @@ module.exports = [
     },
 
     // MV3 background: a service worker, with no window and no document.
+    //
+    // It also may not reach src/shared/state.js. That module's `state` export
+    // is a per-bundle singleton loaded once and mutated in place, which is the
+    // popup's lifetime and not the worker's: the worker is killed when idle,
+    // nothing loads state at module scope, and an unpopulated read used to be
+    // served DEFAULT_STATE silently. Five defects came from background code
+    // reading or writing it (https://git.eeqj.de/sneak/AutistMask/issues/324),
+    // and each point fix added a loadState() that created the next one. The
+    // rule below checks reachability through the whole require graph, not just
+    // the direct require, because a re-export from any shared module the
+    // background already pulls in would put the singleton back in the bundle
+    // with no background file naming it.
     {
         files: ["src/background/**/*.js"],
+        plugins: { background: backgroundState },
         languageOptions: {
             ...commonjs,
             globals: { ...globals.serviceworker, ...extensionGlobals },
         },
+        rules: {
+            "background/no-state-singleton-in-background": "error",
+        },
     },
 
     // src/shared is bundled into both, so it may only use what both provide:
@@ -107,9 +124,9 @@ module.exports = [
         },
     },
 
-    // Unit tests: jest on node.
+    // Unit tests, and the helpers they require: jest on node.
     {
-        files: ["tests/**/*.test.js"],
+        files: ["tests/**/*.test.js", "tests/support/**/*.js"],
         languageOptions: {
             ...commonjs,
             globals: { ...globals.node, ...globals.jest },

manifest/chrome.json

@@ -3,6 +3,7 @@
     "name": "AutistMask",
     "version": "0.1.0",
     "description": "Minimal Ethereum wallet for Chrome",
+    "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzy/G9gT4Z3Ci0HCmthUPEiCjENg+5meZpjdogyT7SiMfxENtHdrpDL6wGhAg1Dk0f1C67Ft8OYpMrMH3kiP2Wnt0UpHo45PY0YUUYzdJgbsp8u0kaykd5FFiY6FycIIFaTniMuh7wRKuNNdJWly+H3aG7qZ6nGu5PIMdb1GXUk35hY+yl7dz5dqFFYUCyxvWCT9XGBSYiI+XRBB/rVZjMWfWpaTmRPdOZ4+GO/Lx0OdMxKlPA/kLWoPot5vMlLn2FDPu6sASphiu7dKZnrINW+h/27jlHMJQS0jncB1EgqOHW0vbXrZnTveFX6UW+Qp86FfSkikhKtQgTW2A4mtWawIDAQAB",
     "permissions": ["storage", "activeTab", "alarms"],
     "host_permissions": ["<all_urls>"],
     "content_security_policy": {

script/lib/eslint/noStateSingletonInBackground.js

@@ -0,0 +1,184 @@
+// ESLint rule: the background bundle may not reach the shared state singleton.
+//
+// src/shared/state.js holds a module-level `state` object, loaded once by
+// loadState() and mutated in place from then on. That is the popup's model. In
+// the MV3 service worker there is no "once": the worker is terminated when
+// idle and revived by the next message, nothing loads state at module scope,
+// and an unpopulated read used to be served DEFAULT_STATE without complaint —
+// five defects, one cause
+// (https://git.eeqj.de/sneak/AutistMask/issues/324). The background has its
+// own per-call storage layer in src/background/state.js instead.
+//
+// THIS RULE IS NOT THE GUARANTEE, and must not be described as one. The
+// guarantee is in build.js: FORBIDDEN_INPUTS / assertNoForbiddenInputs() fails
+// the build when esbuild's own metafile reports src/shared/state.js as an input
+// of a background bundle. That consults the resolution esbuild actually
+// performed, so no specifier syntax and no resolution rule can slip past it,
+// and Dockerfile:42 runs `make build` in CI.
+//
+// What this rule is: fast local feedback, in the editor and in `make lint`,
+// before a full bundle. It reads sources from disk and matches import
+// specifiers TEXTUALLY, so it is a best-effort approximation of module
+// resolution — a hand-rolled matcher will diverge from a real bundler, and two
+// earlier revisions of this file proved it by shipping holes (a template
+// literal, a dynamic `import()`, a comment inside the call, a directory
+// resolved through `package.json` `main`). Those are all covered now, and the
+// next divergence is caught by the build rather than by widening this again.
+//
+// It checks REACHABILITY, not just the direct require: the singleton is one
+// `require()` away from any shared module the background pulls in, and a
+// re-export would put it back in the bundle without any background file naming
+// it. So each background file is the root of a walk over the CommonJS require
+// graph, and the error names the whole chain that brought the singleton in.
+//
+// Matching textually over-approximates — a specifier inside a comment or a
+// string counts — which is the safe direction here: the failure mode is a
+// spurious error naming an exact file and line, not a silent hole.
+//
+// Deliberately not matched: a computed specifier, `require("../shared/" +
+// "state")`. esbuild cannot resolve that statically either, so it never
+// reaches the bundle.
+
+const fs = require("fs");
+const path = require("path");
+
+// The module this rule exists to keep out, relative to the repo root.
+const FORBIDDEN = path.join("src", "shared", "state.js");
+
+// Whatever may sit between a keyword, a paren and a specifier: whitespace and
+// comments. `import(/* webpackChunkName: "x" */ "./x")` is a standard bundler
+// idiom, and an inline `/* eslint-… */` is just as ordinary, so a matcher that
+// allows only \s there is not strict, it is broken. Each alternative starts
+// with a distinct character, so this cannot backtrack quadratically.
+const GAP = "(?:\\s|/\\*[^]*?\\*/|//[^\\n]*)";
+const SPECIFIER = "[\"'`]([^\"'`]+)[\"'`]";
+
+// Both alternatives capture the specifier: call form first
+// (`require(...)`/`import(...)`), then clause form (`from "x"`, and the bare
+// side-effect `import "x"`). Nothing after the specifier is matched, so a
+// trailing comment or a trailing comma cannot break the match either.
+const SPECIFIER_RE = new RegExp(
+    `\\b(?:require|import)${GAP}*\\(${GAP}*${SPECIFIER}` +
+        `|\\b(?:from|import)${GAP}+${SPECIFIER}`,
+    "g",
+);
+
+// The `main` of a directory's package.json, as a specifier relative to that
+// directory, or null. esbuild resolves a directory through it, so a walk that
+// stops at `<dir>/index.js` reports a specifier it matched perfectly well as
+// unresolvable.
+function packageMain(dir) {
+    try {
+        const pkg = JSON.parse(
+            fs.readFileSync(path.join(dir, "package.json"), "utf8"),
+        );
+        return typeof pkg.main === "string" && pkg.main ? pkg.main : null;
+    } catch {
+        return null;
+    }
+}
+
+// Resolve a relative require to a file path, trying what node and esbuild would
+// in the order they would: the path itself, then extensions, then the directory
+// (its package.json `main`, then its index.js).
+function resolveRelative(fromFile, spec) {
+    if (!spec.startsWith(".")) return null; // a package, not our tree
+    const base = path.resolve(path.dirname(fromFile), spec);
+    const main = packageMain(base);
+    for (const candidate of [
+        base,
+        base + ".js",
+        base + ".json",
+        ...(main
+            ? [path.resolve(base, main), path.resolve(base, main) + ".js"]
+            : []),
+        path.join(base, "index.js"),
+    ]) {
+        try {
+            if (fs.statSync(candidate).isFile()) return candidate;
+        } catch {
+            // Not this candidate.
+        }
+    }
+    return null;
+}
+
+function requiresOf(file) {
+    let source;
+    try {
+        source = fs.readFileSync(file, "utf8");
+    } catch {
+        return [];
+    }
+    const out = [];
+    for (const match of source.matchAll(SPECIFIER_RE)) {
+        const resolved = resolveRelative(file, match[1] ?? match[2]);
+        if (resolved) out.push(resolved);
+    }
+    return out;
+}
+
+// Breadth-first from `entry`, returning the shortest chain of files that ends
+// at the forbidden module, or null when it is not reachable.
+function chainToForbidden(entry, forbidden) {
+    const seen = new Set([entry]);
+    const queue = [[entry]];
+    while (queue.length > 0) {
+        const chain = queue.shift();
+        for (const next of requiresOf(chain[chain.length - 1])) {
+            if (next === forbidden) return chain.concat([next]);
+            if (seen.has(next)) continue;
+            seen.add(next);
+            queue.push(chain.concat([next]));
+        }
+    }
+    return null;
+}
+
+const rule = {
+    meta: {
+        type: "problem",
+        docs: {
+            description:
+                "the background bundle must not be able to reach the" +
+                " module-level state singleton in src/shared/state.js",
+        },
+        schema: [],
+        messages: {
+            reachable:
+                "The background must not reach the shared state singleton:" +
+                " {{chain}}. The MV3 worker never populates it, so reading it" +
+                " serves DEFAULT_STATE. Use getState()/updateState() from" +
+                " src/background/state.js instead.",
+        },
+    },
+
+    create(context) {
+        return {
+            "Program:exit"(node) {
+                const filename = context.filename;
+                // ESLint lints from the repo root, which is also where the
+                // forbidden path is anchored.
+                const forbidden = path.resolve(context.cwd, FORBIDDEN);
+                const chain = chainToForbidden(
+                    path.resolve(filename),
+                    forbidden,
+                );
+                if (!chain) return;
+                context.report({
+                    node,
+                    messageId: "reachable",
+                    data: {
+                        chain: chain
+                            .map((file) => path.relative(context.cwd, file))
+                            .join(" -> "),
+                    },
+                });
+            },
+        };
+    },
+};
+
+module.exports = {
+    rules: { "no-state-singleton-in-background": rule },
+};

script/lib/package.js

@@ -0,0 +1,294 @@
+// Turn a verified dist/ into the two distributable archives.
+//
+// Invoked by script/package, which runs `make build` first so that dist/ has
+// already been checked against the build's own receipt (see the Build Receipts
+// section of README.md). This program does not build anything and does not
+// write into dist/: it reads the emitted tree and writes release/.
+//
+//   release/autistmask-chrome-<version>.zip   loaded via chrome://extensions
+//   release/autistmask-firefox-<version>.xpi  an UNSIGNED add-on, see README
+//   release/SHA256SUMS
+//
+// Self-containment is checked rather than assumed, because the layout invites
+// exactly one mistake: build.js emits dist/styles.css at the dist/ ROOT,
+// outside both browser directories, and copies it into each of them as
+// src/popup/styles.css. A naive `zip -r dist/chrome` is therefore correct only
+// by accident, and would stop being correct the moment a reference pointed up
+// and out. So every path the manifest and the popup HTML reference is resolved
+// and required to be inside the archive, a reference that escapes the browser
+// directory is a hard failure, and anything sitting at the dist/ root is
+// listed as deliberately not shipped rather than silently dropped.
+//
+// The archive is then read back and compared byte for byte against the
+// directory it was built from. An archive nobody opened is a claim, not an
+// artifact.
+
+"use strict";
+
+const crypto = require("crypto");
+const fs = require("fs");
+const path = require("path");
+
+const { readZip, writeZip } = require("./zip");
+const { resolveVersion } = require("./version");
+
+const ROOT = path.resolve(__dirname, "..", "..");
+const DIST = path.join(ROOT, "dist");
+const RELEASE = path.join(ROOT, "release");
+
+const TARGETS = [
+    { dir: "chrome", ext: "zip" },
+    // .xpi rather than .zip: it is the same container, but Firefox's install
+    // flow keys off the extension.
+    { dir: "firefox", ext: "xpi" },
+];
+
+// Strings in a manifest that name a file the extension loads. Matched by
+// shape, not by a list of manifest keys, so a key added in a later manifest
+// version is covered the day it appears rather than the day someone remembers
+// to extend a list here. Nothing else in either manifest looks like this: the
+// CSP strings, "<all_urls>", the version and the base64 key all fail it.
+const MANIFEST_PATH_RE =
+    /^[A-Za-z0-9._][A-Za-z0-9._/-]*\.(?:js|css|html|json|png|svg|woff2?)$/;
+
+// Local references out of an HTML document. Enough for what this repo emits —
+// one stylesheet link and one script tag — and anything it does not understand
+// is reported rather than passed over, see htmlReferences().
+const HTML_REF_RE = /(?:src|href)\s*=\s*["']([^"']+)["']/gi;
+
+function fail(message) {
+    throw new Error(message);
+}
+
+function sha256(buf) {
+    return crypto.createHash("sha256").update(buf).digest("hex");
+}
+
+// Every regular file under dir, as archive-root-relative forward-slashed
+// paths. A symlink is refused rather than followed: build.js emits regular
+// files only, so a link under dist/ is not something the build produced, and
+// dereferencing one would put bytes from outside dist/ into the artifact.
+function listFiles(dir, prefix = "") {
+    const out = [];
+    for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
+        const rel = prefix ? `${prefix}/${entry.name}` : entry.name;
+        if (entry.isSymbolicLink()) {
+            fail(
+                `${dir}/${entry.name} is a symlink. The build emits regular ` +
+                    `files only, so this is not something it produced and it ` +
+                    `will not be archived.`,
+            );
+        } else if (entry.isDirectory()) {
+            out.push(...listFiles(path.join(dir, entry.name), rel));
+        } else if (entry.isFile()) {
+            out.push(rel);
+        } else {
+            fail(
+                `${dir}/${entry.name} is neither a regular file nor a ` +
+                    `directory, so it is not something the build emitted`,
+            );
+        }
+    }
+    return out.sort();
+}
+
+// Collect every string anywhere in the manifest that looks like a file it
+// loads, plus every string that tries to reach outside the extension root.
+// The second half is the point: "../styles.css" never matches
+// MANIFEST_PATH_RE, so without an explicit check an escaping reference would
+// read as "not a path" and the missing file would be found only by a user
+// whose popup rendered unstyled.
+function manifestReferences(value, found = new Set()) {
+    if (typeof value === "string") {
+        if (value.split("/").includes("..")) {
+            fail(
+                `the manifest references ${JSON.stringify(value)}, which ` +
+                    `points outside the extension root. Everything the ` +
+                    `browser loads has to be inside the archive; nothing ` +
+                    `above it is shipped.`,
+            );
+        }
+        if (MANIFEST_PATH_RE.test(value)) found.add(value);
+    } else if (Array.isArray(value)) {
+        for (const v of value) manifestReferences(v, found);
+    } else if (value && typeof value === "object") {
+        for (const v of Object.values(value)) manifestReferences(v, found);
+    }
+    return found;
+}
+
+// Local references out of one HTML member, resolved against that member's own
+// directory and returned archive-relative. Absolute URLs, data: URIs and
+// in-page anchors are not files and are skipped; a relative reference that
+// climbs out of the archive root is a failure for the same reason as above.
+function htmlReferences(member, text) {
+    const base = path.posix.dirname(member);
+    const out = new Set();
+    for (const match of text.matchAll(HTML_REF_RE)) {
+        const ref = match[1].trim();
+        if (ref === "" || ref.startsWith("#") || ref.startsWith("//")) continue;
+        if (/^[a-z][a-z0-9+.-]*:/i.test(ref)) continue;
+        if (ref.startsWith("/")) {
+            fail(
+                `${member} references ${JSON.stringify(ref)} from the ` +
+                    `extension root. Nothing here emits root-absolute ` +
+                    `references and this packager does not resolve them.`,
+            );
+        }
+        const resolved = path.posix.normalize(path.posix.join(base, ref));
+        if (resolved.startsWith("..")) {
+            fail(
+                `${member} references ${JSON.stringify(ref)}, which resolves ` +
+                    `outside the extension root. build.js copies the ` +
+                    `compiled stylesheet into each browser directory for ` +
+                    `exactly this reason: dist/styles.css lives at the dist/ ` +
+                    `root and is not part of either archive.`,
+            );
+        }
+        out.add(resolved);
+    }
+    return out;
+}
+
+// Everything the browser is told to load, and the assertion that all of it is
+// in the archive.
+function checkSelfContained(target, members, read) {
+    if (!members.includes("manifest.json")) {
+        fail(`dist/${target} has no manifest.json at its root`);
+    }
+
+    const manifest = JSON.parse(read("manifest.json").toString("utf8"));
+    const referenced = new Set(manifestReferences(manifest));
+
+    for (const member of members) {
+        if (!member.endsWith(".html")) continue;
+        for (const ref of htmlReferences(
+            member,
+            read(member).toString("utf8"),
+        )) {
+            referenced.add(ref);
+        }
+    }
+
+    const missing = [...referenced].filter((r) => !members.includes(r));
+    if (missing.length > 0) {
+        fail(
+            `the ${target} archive would not be self-contained: it is told ` +
+                `to load ${missing.join(", ")}, which ${
+                    missing.length === 1 ? "is" : "are"
+                } not in it`,
+        );
+    }
+    return { manifest, referenced };
+}
+
+function main() {
+    const version = resolveVersion(ROOT);
+
+    if (!fs.existsSync(DIST)) {
+        fail(
+            "there is no dist/ to package. script/package runs make build " +
+                "first; run it rather than this program.",
+        );
+    }
+
+    fs.rmSync(RELEASE, { recursive: true, force: true });
+    fs.mkdirSync(RELEASE, { recursive: true });
+
+    // Files the build emits at the dist/ root, outside both browser
+    // directories. Printed rather than ignored: dist/styles.css is the
+    // Tailwind output that build.js then copies into each browser directory,
+    // so leaving it out is correct — but "correct and stated" and "dropped by
+    // a glob" are different things, and only one of them survives the next
+    // change to the build.
+    const rootOnly = fs
+        .readdirSync(DIST, { withFileTypes: true })
+        .filter((e) => !e.isDirectory())
+        .map((e) => e.name)
+        .sort();
+    if (rootOnly.length > 0) {
+        console.log(
+            `Not shipped (dist/ root, outside every browser directory, and ` +
+                `referenced by nothing inside one): ${rootOnly.join(", ")}`,
+        );
+    }
+
+    const sums = [];
+    for (const { dir, ext } of TARGETS) {
+        const targetDir = path.join(DIST, dir);
+        if (!fs.existsSync(targetDir)) {
+            fail(`dist/${dir} does not exist; run make build`);
+        }
+
+        const members = listFiles(targetDir);
+        const readFromDir = (member) =>
+            fs.readFileSync(path.join(targetDir, member));
+
+        const { manifest } = checkSelfContained(dir, members, readFromDir);
+        if (manifest.version !== version) {
+            fail(
+                `dist/${dir}/manifest.json says version ${manifest.version} ` +
+                    `but this tree is ${version}. dist/ is stale: run make ` +
+                    `build.`,
+            );
+        }
+
+        const archive = writeZip(
+            members.map((name) => ({ name, data: readFromDir(name) })),
+        );
+        const name = `autistmask-${dir}-${version}.${ext}`;
+        const outPath = path.join(RELEASE, name);
+        fs.writeFileSync(outPath, archive);
+
+        // Read the artifact back off disk, not the buffer that was just
+        // written: what ships is the file.
+        const written = fs.readFileSync(outPath);
+        const entries = readZip(written);
+        const inArchive = entries.map((e) => e.name).sort();
+        if (inArchive.join("\n") !== members.join("\n")) {
+            fail(
+                `${name} does not hold the same members as dist/${dir}: ` +
+                    `archive has ${inArchive.length}, directory has ` +
+                    `${members.length}`,
+            );
+        }
+        for (const entry of entries) {
+            const onDisk = readFromDir(entry.name);
+            if (sha256(entry.data) !== sha256(onDisk)) {
+                fail(`${name} member ${entry.name} differs from dist/${dir}`);
+            }
+        }
+        // Re-run the self-containment check against the ARCHIVE's own
+        // contents. The directory passing it is not the claim being made.
+        const byName = new Map(entries.map((e) => [e.name, e.data]));
+        checkSelfContained(dir, inArchive, (m) => byName.get(m));
+
+        const digest = sha256(written);
+        sums.push(`${digest}  ${name}`);
+        console.log(
+            `${name}: ${entries.length} member(s), ${written.length} bytes, ` +
+                `sha256 ${digest}`,
+        );
+    }
+
+    fs.writeFileSync(
+        path.join(RELEASE, "SHA256SUMS"),
+        sums.map((l) => `${l}\n`).join(""),
+    );
+    console.log(`Wrote release/ for version ${version}`);
+}
+
+// Only when run as a program. The reference-resolving helpers are what decide
+// whether an archive is self-contained, so tests/packaging.test.js exercises
+// them directly and must be able to require this file without packaging
+// anything.
+if (require.main === module) {
+    try {
+        main();
+    } catch (err) {
+        console.error(`package: ${err && err.message ? err.message : err}`);
+        process.exit(1);
+    }
+}
+
+module.exports = { checkSelfContained, htmlReferences, manifestReferences };

script/lib/version.js

@@ -0,0 +1,74 @@
+// The version, and the rule that there is only one of it.
+//
+// Three files declare a version and none of them can be derived from another:
+// Chrome and Firefox each need their own manifest, both are copied to dist/
+// verbatim (tests/manifest.test.js asserts that what is in manifest/ is what
+// ships), and package.json's copy is what build.js compiles into the About
+// screen. So the single source of truth is enforced rather than generated —
+// they must all agree or there is no version and no build.
+//
+// Reading one of the three and ignoring the rest is what this replaces. That
+// shape cannot fail: it silently ships an extension whose About screen and
+// whose browser-reported version disagree, and whose release artifact is named
+// after whichever file the packager happened to read.
+//
+// Required by build.js, script/lib/package.js and tests/version.test.js, so
+// the build, the release artifacts and make check all apply the same rule to
+// the same files.
+
+"use strict";
+
+const fs = require("fs");
+const path = require("path");
+
+const VERSION_SOURCES = [
+    "package.json",
+    "manifest/chrome.json",
+    "manifest/firefox.json",
+];
+
+// Every declared version, in VERSION_SOURCES order, as { source, version }.
+// A file that declares nothing usable fails here rather than being skipped:
+// a missing version is not agreement.
+function declaredVersions(root) {
+    return VERSION_SOURCES.map((source) => {
+        const file = path.join(root, source);
+        let parsed;
+        try {
+            parsed = JSON.parse(fs.readFileSync(file, "utf8"));
+        } catch (e) {
+            throw new Error(
+                `${source} could not be read as JSON: ${e.message}`,
+            );
+        }
+        const version = parsed.version;
+        if (typeof version !== "string" || version.trim() === "") {
+            throw new Error(
+                `${source} declares no usable "version" (found ` +
+                    `${JSON.stringify(version)}). Every artifact is named and ` +
+                    `stamped with it, so there is nothing to build without it.`,
+            );
+        }
+        return { source, version };
+    });
+}
+
+// The one version all three declare, or a failure naming every disagreeing
+// file and what it said.
+function resolveVersion(root) {
+    const declared = declaredVersions(root);
+    const distinct = [...new Set(declared.map((d) => d.version))];
+    if (distinct.length !== 1) {
+        throw new Error(
+            "the declared versions disagree, so this tree has no version: " +
+                declared.map((d) => `${d.source}=${d.version}`).join(", ") +
+                ". Set all of them to the same value: the manifests are what " +
+                "the browser reports and package.json is what the About " +
+                "screen shows, and a build that picked one of them would " +
+                "ship the disagreement.",
+        );
+    }
+    return distinct[0];
+}
+
+module.exports = { VERSION_SOURCES, declaredVersions, resolveVersion };

script/lib/zip.js

@@ -0,0 +1,274 @@
+// A minimal, deterministic ZIP writer and reader.
+//
+// Used by script/lib/package.js to build the distributable archives: a Chrome
+// zip and a Firefox XPI are both ordinary zip files with manifest.json at the
+// root, so one implementation covers both.
+//
+// Why this rather than a package or the zip(1) binary. A dependency would have
+// to be hash-pinned like everything else in REPO_POLICIES.md, and this is
+// about a hundred lines of stdlib zlib for a format the archives use two
+// features of. The binary is worse: the release artifact would then depend on
+// whichever Info-ZIP the machine happens to have, which is the same objection
+// that keeps linting inside a container.
+//
+// Deterministic on purpose. Entries are sorted by name, every timestamp is the
+// same fixed 1980-01-01 the format's epoch starts at, and the compression
+// level is fixed, so building the same dist/ twice produces byte-identical
+// archives and the sha256 in SHA256SUMS is a property of the input rather than
+// of the clock. Two builds of the same commit that disagree are then visible
+// instead of expected.
+//
+// Deliberately NOT implemented: zip64, encryption, data descriptors,
+// directory entries (browsers infer directories from member paths), and
+// anything to do with symlinks. writeZip refuses input it cannot represent
+// rather than emitting an archive that is quietly wrong.
+
+"use strict";
+
+const zlib = require("zlib");
+
+const LOCAL_SIG = 0x04034b50;
+const CENTRAL_SIG = 0x02014b50;
+const EOCD_SIG = 0x06054b50;
+
+const METHOD_STORE = 0;
+const METHOD_DEFLATE = 8;
+
+// 1980-01-01 00:00:00, the earliest the MS-DOS timestamp fields can express.
+const DOS_DATE = (0 << 9) | (1 << 5) | 1;
+const DOS_TIME = 0;
+
+// Unix regular file, mode 0644, in the high 16 bits, which is where the "made
+// by unix" convention puts it.
+// >>> 0 because JS shifts are signed 32-bit and this one sets the top bit.
+const EXTERNAL_ATTRS = (0o100644 << 16) >>> 0;
+const VERSION_MADE_BY = (3 << 8) | 20; // unix, needs zip 2.0
+const VERSION_NEEDED = 20;
+
+// Without zip64 every size and offset is a u32.
+const MAX_U32 = 0xffffffff;
+
+const CRC_TABLE = (() => {
+    const table = new Int32Array(256);
+    for (let i = 0; i < 256; i++) {
+        let c = i;
+        for (let k = 0; k < 8; k++) {
+            c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1;
+        }
+        table[i] = c;
+    }
+    return table;
+})();
+
+// Written out rather than taken from zlib.crc32, which only exists from node
+// 22.2: this runs from script/ on whatever node the host has as well as inside
+// the pinned image, and a checksum that silently is not there is worse than
+// twelve lines.
+function crc32(buf) {
+    let c = -1;
+    for (let i = 0; i < buf.length; i++) {
+        c = CRC_TABLE[(c ^ buf[i]) & 0xff] ^ (c >>> 8);
+    }
+    return (c ^ -1) >>> 0;
+}
+
+// Member names are stored as raw bytes. Anything outside ASCII would need the
+// UTF-8 flag and interoperability care that nothing this repo emits requires,
+// so it is refused instead of guessed at.
+function encodeName(name) {
+    if (typeof name !== "string" || name === "") {
+        throw new Error(`zip: unusable member name ${JSON.stringify(name)}`);
+    }
+    const segments = name.split("/");
+    if (
+        name.startsWith("/") ||
+        name.includes("\\") ||
+        segments.some((s) => s === "" || s === "." || s === "..")
+    ) {
+        throw new Error(
+            `zip: refusing member name ${JSON.stringify(name)}: archive ` +
+                `members must be relative paths under the archive root`,
+        );
+    }
+    if (/[^\x20-\x7e]/.test(name)) {
+        throw new Error(
+            `zip: refusing non-ASCII member name ${JSON.stringify(name)}`,
+        );
+    }
+    return Buffer.from(name, "ascii");
+}
+
+function compress(data) {
+    if (data.length === 0) {
+        return { method: METHOD_STORE, body: data };
+    }
+    const deflated = zlib.deflateRawSync(data, { level: 9 });
+    if (deflated.length >= data.length) {
+        return { method: METHOD_STORE, body: data };
+    }
+    return { method: METHOD_DEFLATE, body: deflated };
+}
+
+// entries: [{ name, data }]. Returns the archive as a Buffer.
+function writeZip(entries) {
+    if (!Array.isArray(entries) || entries.length === 0) {
+        throw new Error("zip: refusing to write an archive with no members");
+    }
+
+    const sorted = [...entries].sort((a, b) => (a.name < b.name ? -1 : 1));
+    const seen = new Set();
+    const locals = [];
+    const centrals = [];
+    let offset = 0;
+
+    for (const entry of sorted) {
+        const name = encodeName(entry.name);
+        if (seen.has(entry.name)) {
+            throw new Error(`zip: duplicate member ${entry.name}`);
+        }
+        seen.add(entry.name);
+
+        const data = Buffer.from(entry.data);
+        const { method, body } = compress(data);
+        if (data.length > MAX_U32 || body.length > MAX_U32) {
+            throw new Error(
+                `zip: ${entry.name} is too large for a non-zip64 archive`,
+            );
+        }
+        const crc = crc32(data);
+
+        const local = Buffer.alloc(30 + name.length);
+        local.writeUInt32LE(LOCAL_SIG, 0);
+        local.writeUInt16LE(VERSION_NEEDED, 4);
+        local.writeUInt16LE(0, 6);
+        local.writeUInt16LE(method, 8);
+        local.writeUInt16LE(DOS_TIME, 10);
+        local.writeUInt16LE(DOS_DATE, 12);
+        local.writeUInt32LE(crc, 14);
+        local.writeUInt32LE(body.length, 18);
+        local.writeUInt32LE(data.length, 22);
+        local.writeUInt16LE(name.length, 26);
+        local.writeUInt16LE(0, 28);
+        name.copy(local, 30);
+
+        const central = Buffer.alloc(46 + name.length);
+        central.writeUInt32LE(CENTRAL_SIG, 0);
+        central.writeUInt16LE(VERSION_MADE_BY, 4);
+        central.writeUInt16LE(VERSION_NEEDED, 6);
+        central.writeUInt16LE(0, 8);
+        central.writeUInt16LE(method, 10);
+        central.writeUInt16LE(DOS_TIME, 12);
+        central.writeUInt16LE(DOS_DATE, 14);
+        central.writeUInt32LE(crc, 16);
+        central.writeUInt32LE(body.length, 20);
+        central.writeUInt32LE(data.length, 24);
+        central.writeUInt16LE(name.length, 28);
+        central.writeUInt16LE(0, 30);
+        central.writeUInt16LE(0, 32);
+        central.writeUInt16LE(0, 34);
+        central.writeUInt16LE(0, 36);
+        central.writeUInt32LE(EXTERNAL_ATTRS, 38);
+        if (offset > MAX_U32) {
+            throw new Error("zip: archive too large for a non-zip64 archive");
+        }
+        central.writeUInt32LE(offset, 42);
+        name.copy(central, 46);
+
+        locals.push(local, body);
+        centrals.push(central);
+        offset += local.length + body.length;
+    }
+
+    const centralBuf = Buffer.concat(centrals);
+    const eocd = Buffer.alloc(22);
+    eocd.writeUInt32LE(EOCD_SIG, 0);
+    eocd.writeUInt16LE(0, 4);
+    eocd.writeUInt16LE(0, 6);
+    eocd.writeUInt16LE(sorted.length, 8);
+    eocd.writeUInt16LE(sorted.length, 10);
+    eocd.writeUInt32LE(centralBuf.length, 12);
+    eocd.writeUInt32LE(offset, 16);
+    eocd.writeUInt16LE(0, 20);
+
+    return Buffer.concat([...locals, centralBuf, eocd]);
+}
+
+// Read an archive back into [{ name, data }], from the central directory
+// rather than by scanning for local headers: the central directory is the
+// authoritative index, and a member reachable only by scanning is one a real
+// unzipper would not extract.
+//
+// Every member's CRC is checked. The point of reading an archive back is to
+// establish that it holds what it was meant to hold, so a member that does not
+// decompress to its recorded checksum is a failure and never a warning.
+function readZip(buf) {
+    if (buf.length < 22) {
+        throw new Error("zip: too short to be an archive");
+    }
+    // No archive this writes has a trailing comment, so the EOCD is the last
+    // 22 bytes. Anything else is not an archive this produced.
+    const eocdAt = buf.length - 22;
+    if (buf.readUInt32LE(eocdAt) !== EOCD_SIG) {
+        throw new Error(
+            "zip: no end-of-central-directory record at the end of the " +
+                "archive (a trailing comment, or not a zip at all)",
+        );
+    }
+    const count = buf.readUInt16LE(eocdAt + 10);
+    const centralSize = buf.readUInt32LE(eocdAt + 12);
+    let at = buf.readUInt32LE(eocdAt + 16);
+    if (at + centralSize > eocdAt) {
+        throw new Error("zip: central directory runs past the archive");
+    }
+
+    const out = [];
+    for (let i = 0; i < count; i++) {
+        if (buf.readUInt32LE(at) !== CENTRAL_SIG) {
+            throw new Error(`zip: bad central directory entry ${i}`);
+        }
+        const method = buf.readUInt16LE(at + 10);
+        const crc = buf.readUInt32LE(at + 16);
+        const compSize = buf.readUInt32LE(at + 20);
+        const rawSize = buf.readUInt32LE(at + 24);
+        const nameLen = buf.readUInt16LE(at + 28);
+        const extraLen = buf.readUInt16LE(at + 30);
+        const commentLen = buf.readUInt16LE(at + 32);
+        const localAt = buf.readUInt32LE(at + 42);
+        const name = buf.toString("ascii", at + 46, at + 46 + nameLen);
+        at += 46 + nameLen + extraLen + commentLen;
+
+        if (buf.readUInt32LE(localAt) !== LOCAL_SIG) {
+            throw new Error(`zip: ${name} has no local header`);
+        }
+        // The local header's own name and extra lengths, not the central
+        // directory's: the two are allowed to differ and the data starts after
+        // the local ones.
+        const localNameLen = buf.readUInt16LE(localAt + 26);
+        const localExtraLen = buf.readUInt16LE(localAt + 28);
+        const dataAt = localAt + 30 + localNameLen + localExtraLen;
+        const body = buf.subarray(dataAt, dataAt + compSize);
+
+        let data;
+        if (method === METHOD_STORE) {
+            data = Buffer.from(body);
+        } else if (method === METHOD_DEFLATE) {
+            data = zlib.inflateRawSync(body);
+        } else {
+            throw new Error(`zip: ${name} uses compression method ${method}`);
+        }
+
+        if (data.length !== rawSize) {
+            throw new Error(
+                `zip: ${name} decompressed to ${data.length} bytes, not the ` +
+                    `recorded ${rawSize}`,
+            );
+        }
+        if (crc32(data) !== crc) {
+            throw new Error(`zip: ${name} fails its recorded CRC32`);
+        }
+        out.push({ name, data });
+    }
+    return out;
+}
+
+module.exports = { crc32, readZip, writeZip };

script/package

@@ -0,0 +1,38 @@
+#!/bin/sh
+# script/package: produce the release artifacts — one self-contained,
+# versioned archive per browser — into release/. Our own extension to
+# scripts-to-rule-them-all.
+#
+# It builds first, through `make build` rather than by calling build.js
+# itself. That target is the only audited path to a release build: it creates
+# the build receipt outside the repo, scrubs AUTISTMASK_DEBUG from the
+# verifier's environment, tells script/verify-build in so many words to expect
+# a RELEASE build, and re-runs script/check-censored against dist/.
+# script/test-verify-build asserts that wiring by reading the recipe back out
+# of `make -n`. Re-implementing that sequence here would give the release
+# artifacts a second, unaudited path to dist/ — and it is the release
+# artifacts, above everything else, that must never be built from a debug
+# compile.
+#
+# This packages, it does not publish. Tagging, CRX packing and any upload are
+# outward-facing acts and are nobody's job but the owner's.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+
+    if ! command -v make >/dev/null 2>&1; then
+        echo "package: make is required (the release build runs through" \
+            "make build)" >&2
+        exit 1
+    fi
+
+    make build
+
+    echo "Packaging release artifacts..."
+    node script/lib/package.js
+}
+
+main "$@"

script/test-e2e

@@ -78,6 +78,22 @@ main() {
         -e "E2E_TRACE_NETWORK=${E2E_TRACE_NETWORK:-0}" \
         "$(cat "$IIDFILE")" \
         node tests/e2e/run.js
+
+    # Where chrome.storage.local lives, and what moves it: two unpacked loads
+    # from two different paths in one profile, with the shipped manifest and
+    # again with `key` stripped out. Its own browser sessions — four of them —
+    # because the whole subject is what happens ACROSS loads, which the suite
+    # above cannot express with one.
+    #
+    # No PW_EXPERIMENTAL_SERVICE_WORKER_NETWORK_EVENTS here: this drives no
+    # RPC and installs no route handlers, and the browser is started with
+    # --host-resolver-rules=MAP * ~NOTFOUND so nothing it does can leave.
+    echo "Running the extension-id and storage-partition observations..."
+    docker run --rm \
+        --ipc=host \
+        -e HOME=/tmp \
+        "$(cat "$IIDFILE")" \
+        node tests/e2e/storagePartition.js
 }
 
 main "$@"

script/test-e2e-firefox

@@ -72,6 +72,19 @@ main() {
         -e HOME=/tmp \
         "$(cat "$IIDFILE")" \
         node tests/e2e/firefox/run.js dist/firefox
+
+    # The install/uninstall/re-install property, against the packaged XPI
+    # rather than the unpacked directory: it is the artifact a user would be
+    # handed, and this is the only place a real Firefox is asked to load it.
+    # Its own browser session, because it takes the add-on away in the middle
+    # and the suite above shares one session throughout.
+    echo "Running the Firefox re-install suite against the packaged XPI..."
+    docker run --rm \
+        --shm-size=1g \
+        --network none \
+        -e HOME=/tmp \
+        "$(cat "$IIDFILE")" \
+        node tests/e2e/firefox/reinstall.js
 }
 
 main "$@"

src/background/index.js

@@ -2,19 +2,17 @@
 // Handles EIP-1193 RPC requests from content scripts and proxies
 // non-sensitive calls to the configured Ethereum JSON-RPC endpoint.
 
-const { DEFAULT_RPC_URL } = require("../shared/constants");
 const {
     SUPPORTED_CHAIN_IDS,
     networkById,
     networkByChainId,
 } = require("../shared/networks");
-const { onChainSwitch } = require("../shared/chainSwitch");
-const {
-    state,
-    loadState,
-    saveState,
-    currentNetwork,
-} = require("../shared/state");
+const { applyChainSwitchFields } = require("../shared/chainSwitchFields");
+// The background's own storage layer. src/shared/state.js — the module-level
+// `state` singleton, loadState() and saveState() — is deliberately NOT
+// imported here and must never be: see the header of src/background/state.js,
+// and the lint rule that enforces it in eslint.config.js.
+const { getState, updateState } = require("./state");
 const { refreshBalances, getProvider } = require("../shared/balances");
 const { debugFetch, log } = require("../shared/log");
 const {
@@ -42,7 +40,6 @@ const {
 const {
     actionApi,
     runtimeApi,
-    storageGet,
     tabsQuery,
     tabsSendMessage,
     windowsApi,
@@ -179,21 +176,12 @@ const INTERNAL_ERROR_CODE = -32603;
 const INTERNAL_ERROR_MESSAGE =
     "AutistMask could not complete this request because of an internal error.";
 
-async function getState() {
-    const result = await storageGet("autistmask");
-    return (
-        result.autistmask || {
-            wallets: [],
-            rpcUrl: DEFAULT_RPC_URL,
-            activeAddress: null,
-            allowedSites: {},
-            deniedSites: {},
-        }
-    );
-}
-
-async function getActiveAddress() {
-    const s = await getState();
+// The active address of a profile snapshot. Pure, and taking the snapshot as
+// an argument rather than reading storage itself: a handler that has already
+// read state must not answer "which account is this" from a SECOND, later read
+// — the two can disagree, and the checks that compare them would then be
+// comparing two different moments.
+function activeAddressOf(s) {
     if (s.activeAddress) return s.activeAddress;
     // Fall back to first address
     if (s.wallets.length > 0 && s.wallets[0].addresses.length > 0) {
@@ -202,6 +190,11 @@ async function getActiveAddress() {
     return null;
 }
 
+// For the few call sites that need only the address and hold no snapshot.
+async function getActiveAddress() {
+    return activeAddressOf(await getState());
+}
+
 // Whether a request names a signing address other than the active one. Such a
 // request is refused rather than quietly signed as whichever address happens
 // to be active: the page asked for account A and would otherwise be handed
@@ -210,9 +203,14 @@ function namesAnotherAddress(requested, activeAddress) {
     return !!requested && !sameAddress(requested, activeAddress);
 }
 
+// The endpoint alone, for the one caller that needs nothing else. Anything
+// that also needs the network the endpoint belongs to must take both from ONE
+// snapshot — see handleSendTransaction() — because a chain switch moves them
+// together and a provider built from two different reads can end up pointed at
+// one chain and told it is on another
+// (https://git.eeqj.de/sneak/AutistMask/issues/320).
 async function getRpcUrl() {
-    const s = await getState();
-    return s.rpcUrl || DEFAULT_RPC_URL;
+    return (await getState()).rpcUrl;
 }
 
 function extractHostname(origin) {
@@ -553,10 +551,26 @@ runtime.onConnect.addListener((port) => {
     }
 });
 
+// Record a remembered site decision under one address.
+//
+// A read-modify-write against storage, not a load-mutate-save of a shared
+// singleton: the user takes seconds to answer the prompt, and everything else
+// in the worker — a balance refresh in flight, another site's approval — has
+// gone on running the whole time. Loading here used to replace the very
+// objects that work was holding.
+async function rememberSiteChoice(field, address, hostname) {
+    await updateState((s) => {
+        if (!s[field][address]) s[field][address] = [];
+        if (!s[field][address].includes(hostname)) {
+            s[field][address].push(hostname);
+        }
+    });
+}
+
 // Handle connection requests (eth_requestAccounts, wallet_requestPermissions)
 async function handleConnectionRequest(origin) {
     const s = await getState();
-    const activeAddress = await getActiveAddress();
+    const activeAddress = activeAddressOf(s);
     if (!activeAddress) {
         return { error: { message: "No accounts available" } };
     }
@@ -588,29 +602,14 @@ async function handleConnectionRequest(origin) {
 
     if (decision.approved) {
         if (decision.remember) {
-            // Reload state to get latest, add to allowed, persist
-            await loadState();
-            if (!state.allowedSites[activeAddress]) {
-                state.allowedSites[activeAddress] = [];
-            }
-            if (!state.allowedSites[activeAddress].includes(hostname)) {
-                state.allowedSites[activeAddress].push(hostname);
-            }
-            await saveState();
+            await rememberSiteChoice("allowedSites", activeAddress, hostname);
         } else {
             connectedSites[origin + ":" + activeAddress] = true;
         }
         return { result: [activeAddress] };
     } else {
         if (decision.remember) {
-            await loadState();
-            if (!state.deniedSites[activeAddress]) {
-                state.deniedSites[activeAddress] = [];
-            }
-            if (!state.deniedSites[activeAddress].includes(hostname)) {
-                state.deniedSites[activeAddress].push(hostname);
-            }
-            await saveState();
+            await rememberSiteChoice("deniedSites", activeAddress, hostname);
         }
         return {
             error: {
@@ -654,7 +653,7 @@ async function handleRpc(method, params, origin) {
 
     if (method === "eth_accounts") {
         const s = await getState();
-        const activeAddress = await getActiveAddress();
+        const activeAddress = activeAddressOf(s);
         if (!activeAddress) return { result: [] };
         const hostname = extractHostname(origin);
         const allowed = s.allowedSites[activeAddress] || [];
@@ -667,22 +666,11 @@ async function handleRpc(method, params, origin) {
         return { result: [] };
     }
 
-    // Both answered from currentNetwork(), which reads the module-level state
-    // singleton, and nothing populates that at module scope. A worker revived
-    // by the page's own message therefore held DEFAULT_STATE and told a page
-    // it was on mainnet while the user was on Sepolia
-    // (https://git.eeqj.de/sneak/AutistMask/issues/317).
-    //
-    // Answered from getState() rather than by loading the singleton. Any page
-    // reaches these two — neither is gated on a connection, and the injected
-    // provider sends eth_chainId on every page load — and loadState() replaces
-    // state.wallets wholesale, which would detach the address objects an
-    // in-flight backgroundRefresh() is mutating across its network round trip,
-    // so its saveState() would persist the pre-refresh balances while still
-    // stamping lastBalanceRefresh. getState() is the detached per-call storage
-    // read the other read handlers here already use.
-    // networkById(undefined) falls back to mainnet, matching the default for a
-    // profile with no stored networkId.
+    // Both used to be answered from currentNetwork(), which reads the
+    // module-level state singleton, and nothing populates that at module
+    // scope. A worker revived by the page's own message therefore held
+    // DEFAULT_STATE and told a page it was on mainnet while the user was on
+    // Sepolia (https://git.eeqj.de/sneak/AutistMask/issues/317).
     if (method === "eth_chainId" || method === "net_version") {
         const s = await getState();
         const net = networkById(s.networkId);
@@ -699,7 +687,7 @@ async function handleRpc(method, params, origin) {
         // not be able to do it. Ungated, any page could clear the
         // [TESTNET] banner under a user who believed they were on Sepolia.
         const s = await getState();
-        const activeAddress = await getActiveAddress();
+        const activeAddress = activeAddressOf(s);
         const hostname = extractHostname(origin);
         const allowed = s.allowedSites[activeAddress] || [];
         if (
@@ -709,24 +697,25 @@ async function handleRpc(method, params, origin) {
             return { error: { code: 4100, message: "Unauthorized" } };
         }
 
-        // onChainSwitch() mutates the module-level state singleton and then
-        // saves every field of it, and currentNetwork() reads the same
-        // singleton. This worker may have been started by this very message:
-        // nothing loads state at module scope, so without this the singleton
-        // is DEFAULT_STATE, the same-chain check compares against the wrong
-        // network, and the save writes empty wallets, empty allowedSites and
-        // the default endpoints over the user's stored profile
-        // (https://git.eeqj.de/sneak/AutistMask/issues/316). Same precedent
-        // as the transaction path below.
-        await loadState();
-
+        // The chain in force is read from the snapshot above, not from the
+        // singleton: this worker may have been started by this very message,
+        // and the singleton would then be DEFAULT_STATE, so the same-chain
+        // check compared against mainnet whatever the user was on
+        // (https://git.eeqj.de/sneak/AutistMask/issues/316).
         const chainId = params?.[0]?.chainId;
-        if (chainId === currentNetwork().chainId) {
+        if (chainId === networkById(s.networkId).chainId) {
             return { result: null };
         }
         if (SUPPORTED_CHAIN_IDS.has(chainId)) {
             const target = networkByChainId(chainId);
-            await onChainSwitch(target.id);
+            // Read-modify-write against storage. The old path went through
+            // onChainSwitch(), which mutates the singleton and then persists
+            // every field of it — on an unloaded worker that wrote empty
+            // wallets, empty allowedSites and the default endpoints over the
+            // user's stored profile, encrypted secrets included.
+            await updateState((fresh) =>
+                applyChainSwitchFields(fresh, target.id),
+            );
             broadcastChainChanged(target.chainId);
             return { result: null };
         }
@@ -773,7 +762,7 @@ async function handleRpc(method, params, origin) {
 
     if (method === "wallet_getPermissions") {
         const s = await getState();
-        const activeAddress = await getActiveAddress();
+        const activeAddress = activeAddressOf(s);
         const hostname = extractHostname(origin);
         const allowed = s.allowedSites[activeAddress] || [];
         const isConnected =
@@ -799,7 +788,7 @@ async function handleRpc(method, params, origin) {
 
     if (method === "personal_sign" || method === "eth_sign") {
         const s = await getState();
-        const activeAddress = await getActiveAddress();
+        const activeAddress = activeAddressOf(s);
         if (!activeAddress)
             return { error: { message: "No accounts available" } };
 
@@ -848,7 +837,7 @@ async function handleRpc(method, params, origin) {
 
     if (method === "eth_signTypedData_v4" || method === "eth_signTypedData") {
         const s = await getState();
-        const activeAddress = await getActiveAddress();
+        const activeAddress = activeAddressOf(s);
         if (!activeAddress)
             return { error: { message: "No accounts available" } };
 
@@ -904,7 +893,7 @@ async function handleRpc(method, params, origin) {
 // page has its answer.
 async function handleSendTransaction(params, origin) {
     const s = await getState();
-    const activeAddress = await getActiveAddress();
+    const activeAddress = activeAddressOf(s);
     if (!activeAddress) return { error: { message: "No accounts available" } };
 
     const hostname = extractHostname(origin);
@@ -948,10 +937,19 @@ async function handleSendTransaction(params, origin) {
         // user is shown is a complete one and is the same object the signed
         // artifact is checked against. A failure raises no approval at all and
         // is reported to the requesting page; see approvalTx.js.
+        //
+        // The provider is built from ONE snapshot — the endpoint and the
+        // network name both come from `s`. It used to be
+        // getProvider(await getRpcUrl()) with no network name at all, so
+        // getProvider fell back to the unpopulated singleton's mainnet: the
+        // endpoint was the user's chain and the static hint was 0x1, ethers
+        // fixed chainId at 0x1, and the wallet's own verifySignedTx then
+        // refused every non-mainnet dApp send
+        // (https://git.eeqj.de/sneak/AutistMask/issues/320).
         let approvedTx;
         try {
             approvedTx = await prepareApprovalTx(
-                getProvider(await getRpcUrl()),
+                getProvider(s.rpcUrl, s.networkId),
                 activeAddress,
                 txParams,
             );
@@ -1039,7 +1037,7 @@ async function broadcastAccountsChanged() {
     }
     resetPopupUrl();
     const s = await getState();
-    const activeAddress = await getActiveAddress();
+    const activeAddress = activeAddressOf(s);
     const allowed = activeAddress ? s.allowedSites[activeAddress] || [] : [];
     let tabs;
     try {
@@ -1079,20 +1077,60 @@ async function broadcastAccountsChanged() {
 const BALANCE_REFRESH_PERIOD_MS = BALANCE_REFRESH_PERIOD_MINUTES * 60 * 1000;
 const RECENT_BALANCE_REFRESH_MS = Math.floor(BALANCE_REFRESH_PERIOD_MS / 2);
 
+// The wallets this refresh works on are its OWN, and nothing else in the
+// worker can reach them.
+//
+// refreshBalances() mutates address objects in place across a multi-second
+// network round trip. It used to be handed the module-level singleton's
+// wallets, which meant any concurrent handler that called loadState() replaced
+// state.wallets underneath it: the refreshed balances landed on detached
+// objects, and the save that followed persisted the PRE-refresh values while
+// still stamping lastBalanceRefresh, suppressing the redo. Every point fix for
+// the singleton added such a loadState(), so the next one would have done it
+// again (https://git.eeqj.de/sneak/AutistMask/issues/324).
+//
+// So: read a snapshot, refresh a private copy of its wallets, then apply the
+// balances that came back — by address, onto whatever storage holds NOW.
+// Applying by address rather than writing the array back is what keeps a
+// wallet or address added, renamed or deleted during the round trip.
 async function backgroundRefresh() {
-    await loadState();
+    const s = await getState();
     const now = Date.now();
-    if (now - (state.lastBalanceRefresh || 0) < RECENT_BALANCE_REFRESH_MS)
-        return;
-    if (state.wallets.length === 0) return;
+    if (now - (s.lastBalanceRefresh || 0) < RECENT_BALANCE_REFRESH_MS) return;
+    if (s.wallets.length === 0) return;
+
+    const wallets = s.wallets;
     await refreshBalances(
-        state.wallets,
-        state.rpcUrl,
-        state.blockscoutUrl,
-        state.trackedTokens,
+        wallets,
+        s.rpcUrl,
+        s.blockscoutUrl,
+        s.trackedTokens,
+        s.networkId,
     );
-    state.lastBalanceRefresh = now;
-    await saveState();
+
+    const refreshed = new Map();
+    for (const wallet of wallets) {
+        for (const addr of wallet.addresses || []) {
+            refreshed.set(String(addr.address).toLowerCase(), addr);
+        }
+    }
+
+    await updateState((fresh) => {
+        for (const wallet of fresh.wallets) {
+            for (const addr of wallet.addresses || []) {
+                const got = refreshed.get(String(addr.address).toLowerCase());
+                if (!got) continue;
+                // Only fields the refresh actually produced. refreshBalances()
+                // leaves a field untouched when its lookup failed, so an
+                // undefined here means "no answer", not "the answer is empty",
+                // and must not overwrite what is stored.
+                for (const key of ["balance", "ensName", "tokenBalances"]) {
+                    if (got[key] !== undefined) addr[key] = got[key];
+                }
+            }
+        }
+        fresh.lastBalanceRefresh = now;
+    });
 }
 
 // The recurring job runs off an alarm, not a timer. On Chrome MV3 this file is
@@ -1307,16 +1345,29 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         // so an escape from there must not tell the user it might have.
         let lastResortStage = TX_STAGE_VERIFY;
         (async () => {
-            // The chain this attempt is on, read once. Verification below
-            // refuses an artifact signed for any other chain, and the nonce
-            // record is both consulted and written under this one, so a
-            // network switch part-way through cannot make the check and the
-            // record disagree about which chain the nonce was spent on.
+            // The chain this attempt is on, read once — and the endpoint it
+            // will be broadcast to comes from the SAME read.
+            //
+            // Verification below refuses an artifact signed for any other
+            // chain, and the nonce record is both consulted and written under
+            // this one, so a network switch part-way through cannot make the
+            // check and the record disagree about which chain the nonce was
+            // spent on. The endpoint used to be read separately, several
+            // awaits later (`state.rpcUrl` off the singleton), so a chain
+            // switch committed in that window moved the endpoint out from
+            // under a transaction already verified against the old chain: the
+            // artifact would be sent to the new chain's node, which is
+            // precisely the "signed for a different network" case the
+            // verification exists to prevent.
             let chainId;
+            let rpcUrl;
+            let networkId;
             try {
-                await loadState();
-                chainId = currentNetwork().chainId;
-                const activeAddress = await getActiveAddress();
+                const s = await getState();
+                networkId = s.networkId;
+                chainId = networkById(networkId).chainId;
+                rpcUrl = s.rpcUrl;
+                const activeAddress = activeAddressOf(s);
                 // An address switch between approval and signing refuses. The
                 // approval named one account; signing from whichever account
                 // is active now would send funds from an account this screen
@@ -1388,7 +1439,7 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
             }
 
             try {
-                const provider = getProvider(state.rpcUrl);
+                const provider = getProvider(rpcUrl, networkId);
                 lastResortStage = TX_STAGE_BROADCAST;
                 const tx = await provider.broadcastTransaction(msg.rawSignedTx);
                 if (nonce !== null) spent.add(nonce);

src/background/state.js

@@ -0,0 +1,76 @@
+// The background's access to the persisted profile.
+//
+// There is no in-memory copy here, and that is the whole design. The MV3
+// service worker is terminated when idle and revived by the next message, so
+// anything held at module scope is either absent or arbitrarily stale, and
+// src/shared/state.js's module-level `state` singleton — which nothing in the
+// worker ever populates — silently served DEFAULT_STATE to whoever read it.
+// Five defects came out of that (https://git.eeqj.de/sneak/AutistMask/issues/324),
+// and every point fix for one of them added a loadState() that created the
+// next: loading detaches the objects an in-flight handler is holding.
+//
+// So the background reads per call and writes read-modify-write:
+//
+//   getState()        one storage read, normalized, detached. Nothing else
+//                     holds the object it returns, so a handler may keep it
+//                     across any number of awaits and no concurrent work can
+//                     move it.
+//   updateState(fn)   read fresh, apply fn to that fresh record, write it
+//                     back — all inside a queue, so two background writes
+//                     never interleave, and the read is one storage round trip
+//                     ahead of the write rather than a page lifetime ahead of
+//                     it (which is what made the popup's saveState() need a
+//                     per-field merge against a baseline at all).
+//
+// A handler that must both read and write therefore does its network work
+// against a snapshot it owns, and applies the RESULT inside updateState().
+// It never publishes an object other in-flight work is holding.
+
+const { storageGet, storageSet } = require("../shared/browserApi");
+const { normalizePersisted } = require("../shared/persistedState");
+
+// A fresh, fully-normalized, detached copy of the persisted profile.
+//
+// Normalized rather than raw: a legacy or malformed record is self-healed the
+// same way loadState() heals it for the popup, so the background is never the
+// one context reasoning about a shape the rest of the extension repairs.
+async function getState() {
+    const result = await storageGet("autistmask");
+    return normalizePersisted(result.autistmask);
+}
+
+// Serializes the read-modify-write turns below. Two of them interleaved would
+// each read before the other wrote, and the second write would carry the first
+// one's fields back to their pre-turn values.
+let updateQueue = Promise.resolve();
+
+async function updateStateOnce(mutate) {
+    const s = await getState();
+    await mutate(s);
+    s.hasWallet = Boolean(s.wallets && s.wallets.length > 0);
+    await storageSet({ autistmask: s });
+    return s;
+}
+
+// Apply `mutate` to a record read fresh from storage and write the result
+// back. `mutate` receives a detached, normalized profile and mutates it in
+// place; it may be async, but it must not do anything slow — the window
+// between the read and the write is the window in which another context's
+// write is lost, and keeping it to one storage round trip is what makes a
+// whole-record write safe here.
+//
+// `mutate` must also not call updateState() itself, directly or through
+// anything it awaits: the queue is strictly serial, so the inner turn waits on
+// the outer one, which is waiting on the inner one. That deadlocks the whole
+// background, not just the caller. Mutate the record you were handed.
+//
+// Resolves with the record that was written.
+function updateState(mutate) {
+    const turn = updateQueue.then(() => updateStateOnce(mutate));
+    // The queue must advance even when a turn rejects, or every update after
+    // it queues behind a promise that never settles.
+    updateQueue = turn.catch(() => {});
+    return turn;
+}
+
+module.exports = { getState, updateState };

src/popup/index.js

@@ -53,6 +53,7 @@ async function doRefreshAndRender() {
                 state.rpcUrl,
                 state.blockscoutUrl,
                 state.trackedTokens,
+                state.networkId,
             ),
         ]);
         state.lastBalanceRefresh = Date.now();

src/popup/views/addToken.js

@@ -49,7 +49,11 @@ function init(ctx) {
         infoEl.style.visibility = "visible";
         log.debugf("Looking up token contract", contractAddr);
         try {
-            const info = await lookupTokenInfo(contractAddr, state.rpcUrl);
+            const info = await lookupTokenInfo(
+                contractAddr,
+                state.rpcUrl,
+                state.networkId,
+            );
             log.infof("Adding token", info.symbol, contractAddr);
             state.trackedTokens.push({
                 address: contractAddr,

src/popup/views/addWallet.js

@@ -179,7 +179,7 @@ async function importMnemonic(ctx) {
 
     // Scan for used HD addresses beyond index 0.
     showFlash("Scanning for addresses...", 30000);
-    const scan = await scanForAddresses(xpub, state.rpcUrl);
+    const scan = await scanForAddresses(xpub, state.rpcUrl, state.networkId);
     if (scan.addresses.length > 1) {
         wallet.addresses = scan.addresses.map((a) => ({
             address: a.address,
@@ -298,7 +298,7 @@ async function importXprvKey(ctx) {
 
     // Scan for used HD addresses beyond index 0.
     showFlash("Scanning for addresses...", 30000);
-    const scan = await scanForAddresses(xpub, state.rpcUrl);
+    const scan = await scanForAddresses(xpub, state.rpcUrl, state.networkId);
     if (scan.addresses.length > 1) {
         wallet.addresses = scan.addresses.map((a) => ({
             address: a.address,

src/popup/views/addressDetail.js

@@ -188,6 +188,7 @@ async function loadTransactions(address) {
                 ensNameMap = await resolveEnsNames(
                     counterparties,
                     state.rpcUrl,
+                    state.networkId,
                 );
             } catch {
                 ensNameMap = new Map();

src/popup/views/addressToken.js

@@ -268,6 +268,7 @@ async function loadTransactions(address, tokenId) {
                 ensNameMap = await resolveEnsNames(
                     counterparties,
                     state.rpcUrl,
+                    state.networkId,
                 );
             } catch {
                 ensNameMap = new Map();

src/popup/views/approval.js

@@ -73,6 +73,14 @@ function tokenLabel(address) {
 function decodeCalldata(data, toAddress) {
     if (!data || data === "0x" || data.length < 10) return null;
 
+    // Where a token's scale is looked for, for every decoder below: the ERC-20
+    // amount line and the swap's Amount and Min. received lines resolve it the
+    // same way, and refuse to format the same way when it is nowhere.
+    const decimalsSources = {
+        trackedTokens: state.trackedTokens,
+        wallets: state.wallets,
+    };
+
     // Try ERC-20 (approve / transfer)
     try {
         const parsed = erc20Iface.parseTransaction({ data });
@@ -84,10 +92,10 @@ function decodeCalldata(data, toAddress) {
             // the wrong number, and for a token with fewer decimals than the
             // guess it is the wrong number in the direction that reads as
             // zero. See tokenAmountText().
-            const tokenDecimals = resolveTokenDecimals(toAddress, {
-                trackedTokens: state.trackedTokens,
-                wallets: state.wallets,
-            });
+            const tokenDecimals = resolveTokenDecimals(
+                toAddress,
+                decimalsSources,
+            );
             const contractLabel = tokenSymbol
                 ? tokenSymbol + " (" + toAddress + ")"
                 : toAddress;
@@ -167,7 +175,7 @@ function decodeCalldata(data, toAddress) {
     }
 
     // Try Uniswap Universal Router
-    const routerResult = uniswap.decode(data, toAddress);
+    const routerResult = uniswap.decode(data, toAddress, decimalsSources);
     if (routerResult) return routerResult;
 
     return null;

src/popup/views/confirmTx.js

@@ -304,7 +304,7 @@ function formatFeeEth(wei) {
 
 async function estimateGas(txInfo) {
     try {
-        const provider = getProvider(state.rpcUrl);
+        const provider = getProvider(state.rpcUrl, state.networkId);
         const feeData = await provider.getFeeData();
         let gasLimit;
 
@@ -386,7 +386,7 @@ async function estimateGas(txInfo) {
 
 async function checkRecipientHistory(txInfo) {
     try {
-        const provider = getProvider(state.rpcUrl);
+        const provider = getProvider(state.rpcUrl, state.networkId);
         const asyncWarnings = await getFullWarnings(txInfo.to, provider, {
             fromAddress: txInfo.from,
         });
@@ -454,7 +454,7 @@ function init(_ctx) {
                 state.selectedAddress,
                 decryptedSecret,
             );
-            const provider = getProvider(state.rpcUrl);
+            const provider = getProvider(state.rpcUrl, state.networkId);
             const connectedSigner = signer.connect(provider);
 
             if (pendingTx.token === "ETH") {

src/popup/views/send.js

@@ -202,7 +202,7 @@ function init(_ctx) {
         let ensName = null;
         if (to.includes(".") && !to.startsWith("0x")) {
             try {
-                const provider = getProvider(state.rpcUrl);
+                const provider = getProvider(state.rpcUrl, state.networkId);
                 const resolved = await provider.resolveName(to);
                 if (!resolved) {
                     showFlash("Could not resolve " + to);

src/popup/views/settingsAddToken.js

@@ -133,7 +133,11 @@ function init(_ctx) {
         infoEl.style.visibility = "visible";
         log.debugf("Looking up token contract", addr);
         try {
-            const info = await lookupTokenInfo(addr, state.rpcUrl);
+            const info = await lookupTokenInfo(
+                addr,
+                state.rpcUrl,
+                state.networkId,
+            );
             log.infof("Adding token", info.symbol, addr);
             state.trackedTokens.push({
                 address: addr,

src/popup/views/txStatus.js

@@ -113,7 +113,7 @@ function startWait(txInfo, txHash, broadcastTime, pollNow) {
         renderElapsed();
     }, 1000);
 
-    const provider = getProvider(state.rpcUrl);
+    const provider = getProvider(state.rpcUrl, state.networkId);
     let consecutiveFailures = 0;
 
     async function poll() {

src/shared/approvalAmount.js

@@ -14,6 +14,10 @@
 // them answers, unknownDecimalsAmount() renders the base-unit integer with the
 // unknown scale stated, and no formatUnits() call is reached at all.
 //
+// The Uniswap decoder's Amount and Min. received lines land on this same
+// screen and use these same two functions, so there is one way of resolving a
+// scale and one way of saying there is none.
+//
 // This is the display counterpart to transferAmount.js, which takes the same
 // stance on the wallet's own send path: an amount whose scale is unknown or
 // disputed is refused rather than guessed at.

src/shared/balances.js

@@ -9,6 +9,7 @@ const {
     formatUnits,
 } = require("ethers");
 const { ERC20_ABI } = require("./constants");
+const { NETWORKS } = require("./networks");
 const { log, debugFetch } = require("./log");
 const { deriveAddressFromXpub } = require("./wallet");
 const { TOKEN_BY_ADDRESS } = require("./tokenList");
@@ -17,17 +18,38 @@ const { isSpoofedSymbol } = require("./symbolSpoof");
 
 // Use a static network to skip auto-detection (which can fail and cause
 // "could not coalesce error" on some RPC endpoints like Cloudflare).
-// Accepts an optional networkName ("mainnet" or "sepolia") for the static
-// network hint so ethers picks the right chain parameters.  When omitted,
-// reads the currently selected network from extension state.
-function getProvider(rpcUrl, networkName) {
-    // Lazy require to avoid circular dependency issues at module scope.
-    const { currentNetwork } = require("./state");
-    const name = networkName || currentNetwork().id;
-    const net = Network.from(name);
+//
+// `networkId` is REQUIRED, and is one of the ids in networks.js. It used to be
+// optional, falling back to currentNetwork() — the module-level `state`
+// singleton, which the MV3 service worker never populates. The endpoint then
+// came out right and the static hint came out mainnet, so ethers fixed
+// `chainId` at 0x1 and every non-mainnet dApp send was prepared for the wrong
+// chain and then refused by the wallet's own verifier
+// (https://git.eeqj.de/sneak/AutistMask/issues/320). Requiring it is what
+// stops that from coming back: a caller that has no network to name has no
+// business constructing a provider, and there is no longer a default for it
+// to get silently wrong.
+//
+// Validated against NETWORKS rather than passed straight to Network.from():
+// ethers knows chains this wallet does not, so an id that is not one of ours
+// is a caller bug and must not resolve to a working provider for some other
+// chain.
+function getProvider(rpcUrl, networkId) {
+    const net = Network.from(requireNetworkId(networkId).id);
     return new JsonRpcProvider(rpcUrl, net, { staticNetwork: net });
 }
 
+function requireNetworkId(networkId) {
+    const net = NETWORKS[networkId];
+    if (!net) {
+        throw new Error(
+            "getProvider requires the id of a supported network; got " +
+                JSON.stringify(networkId),
+        );
+    }
+    return net;
+}
+
 function formatBalance(wei) {
     const eth = formatEther(wei);
     const parts = eth.split(".");
@@ -118,9 +140,15 @@ async function fetchTokenBalances(address, blockscoutUrl, trackedTokens) {
 }
 
 // Fetch ETH balances, ENS names, and ERC-20 token balances for all addresses.
-async function refreshBalances(wallets, rpcUrl, blockscoutUrl, trackedTokens) {
+async function refreshBalances(
+    wallets,
+    rpcUrl,
+    blockscoutUrl,
+    trackedTokens,
+    networkId,
+) {
     log.debugf("refreshBalances start, rpc:", rpcUrl);
-    const provider = getProvider(rpcUrl);
+    const provider = getProvider(rpcUrl, networkId);
     const updates = [];
 
     for (const wallet of wallets) {
@@ -193,9 +221,9 @@ async function refreshBalances(wallets, rpcUrl, blockscoutUrl, trackedTokens) {
 
 // Look up token metadata from its contract.
 // Calls symbol() and decimals() to verify it implements ERC-20.
-async function lookupTokenInfo(contractAddress, rpcUrl) {
+async function lookupTokenInfo(contractAddress, rpcUrl, networkId) {
     log.debugf("lookupTokenInfo", contractAddress, "rpc:", rpcUrl);
-    const provider = getProvider(rpcUrl);
+    const provider = getProvider(rpcUrl, networkId);
     const contract = new Contract(contractAddress, ERC20_ABI, provider);
 
     let name, symbol, decimals;
@@ -235,9 +263,9 @@ async function lookupTokenInfo(contractAddress, rpcUrl) {
 // Checks gapLimit addresses in parallel per batch.  Stops when an entire
 // batch has no used addresses (i.e. gapLimit consecutive empty addresses).
 // Returns { addresses: [{ address, index }], nextIndex }.
-async function scanForAddresses(xpub, rpcUrl, gapLimit = 5) {
+async function scanForAddresses(xpub, rpcUrl, networkId, gapLimit = 5) {
     log.debugf("scanForAddresses start, gapLimit:", gapLimit);
-    const provider = getProvider(rpcUrl);
+    const provider = getProvider(rpcUrl, networkId);
     const used = [];
     let checked = 0;
     let checkUpTo = gapLimit;

src/shared/chainSwitch.js

@@ -1,14 +1,23 @@
-// Consolidated chain-switch handler.
+// Consolidated chain-switch handler for the popup.
 //
 // Every state change required when the active network changes is
-// performed here so that callers (settings UI, background
-// wallet_switchEthereumChain, future chain additions) all go
+// performed here so that callers (settings UI, future chain additions) all go
 // through a single code path.
 //
 // Adding a new chain (e.g. ETC) requires only a new entry in
 // networks.js — no per-caller wiring is needed.
+//
+// The background does NOT come through here: this function mutates the
+// module-level `state` singleton, which the MV3 service worker never
+// populates, and a background switch performed on it wrote DEFAULT_STATE over
+// the user's whole profile
+// (https://git.eeqj.de/sneak/AutistMask/issues/316). The field mutations
+// themselves live in chainSwitchFields.js, which takes the record to mutate as
+// an argument; src/background/state.js applies them inside a read-modify-write
+// against storage, and the singleton is not reachable from the background
+// bundle at all (enforced by the ESLint rule in eslint.config.js).
 
-const { networkById } = require("./networks");
+const { applyChainSwitchFields } = require("./chainSwitchFields");
 const { clearPrices } = require("./prices");
 
 // Switch the active chain and reset all chain-specific cached state.
@@ -16,56 +25,14 @@ const { clearPrices } = require("./prices");
 async function onChainSwitch(newNetworkId) {
     const { state, saveState } = require("./state");
 
-    const net = networkById(newNetworkId);
-
-    // --- core identity ---
-    // Endpoints are remembered per network rather than reset to the
-    // defaults, because a user who points the wallet at their own node has
-    // no way to get that URL back once it is gone: overwriting it moved
-    // every address and every transaction onto a third-party endpoint
-    // silently and permanently.
-    //
-    // state.rpcUrl / state.blockscoutUrl stay the live endpoints of the
-    // active network, so nothing that reads them changes. The invariant is
-    // that for the ACTIVE network those two fields are authoritative and
-    // the map entry may be stale (Settings writes the fields directly);
-    // for every other network the map is authoritative. Snapshotting the
-    // outgoing network here, before the switch, is what reconciles them.
-    state.networkEndpoints[state.networkId] = {
-        rpcUrl: state.rpcUrl,
-        blockscoutUrl: state.blockscoutUrl,
-    };
-    const remembered = state.networkEndpoints[net.id] || {};
-    state.networkId = net.id;
-    state.rpcUrl = remembered.rpcUrl || net.defaultRpcUrl;
-    state.blockscoutUrl = remembered.blockscoutUrl || net.defaultBlockscoutUrl;
+    const net = applyChainSwitchFields(state, newNetworkId);
 
     // --- price cache ---
     // Prices are chain-specific (testnet tokens are worthless,
-    // ETC has different pricing, etc.).
+    // ETC has different pricing, etc.). In-memory and per bundle, so this is
+    // the popup's own cache — the only context that ever fills it.
     clearPrices();
 
-    // --- balance / refresh state ---
-    // Reset last-refresh timestamp so the next polling cycle
-    // triggers an immediate balance refresh on the new chain.
-    state.lastBalanceRefresh = 0;
-
-    // Clear per-address balances and token balances so stale data
-    // from the previous chain is never displayed while the first
-    // refresh on the new chain is in flight.
-    for (const wallet of state.wallets) {
-        for (const addr of wallet.addresses) {
-            addr.balance = "0";
-            addr.tokenBalances = [];
-        }
-    }
-
-    // --- chain-specific caches ---
-    // Token holder counts and fraud contract lists are
-    // chain-specific and must not carry over.
-    state.tokenHolderCache = {};
-    state.fraudContracts = [];
-
     await saveState();
 
     return net;

src/shared/chainSwitchFields.js

@@ -0,0 +1,69 @@
+// The field mutations a chain switch performs, applied to a state record
+// handed in rather than to the module-level `state` singleton.
+//
+// Split out of chainSwitch.js so the background can perform a chain switch
+// without the singleton being reachable from its bundle at all. The popup
+// still goes through onChainSwitch() (chainSwitch.js), which applies this to
+// the singleton and saves; the background applies it to the detached record of
+// its own read-modify-write (src/background/state.js).
+//
+// Everything here is synchronous and touches nothing but the object it is
+// given: no storage, no caches, no imports beyond the network table. That is
+// what makes it usable on a record that has been read fresh from storage
+// microseconds earlier and is about to be written back.
+
+const { networkById } = require("./networks");
+
+// Switch `s` to `newNetworkId` and reset every piece of chain-specific state
+// it carries. Returns the network configuration object for the new chain.
+function applyChainSwitchFields(s, newNetworkId) {
+    const net = networkById(newNetworkId);
+
+    // --- core identity ---
+    // Endpoints are remembered per network rather than reset to the
+    // defaults, because a user who points the wallet at their own node has
+    // no way to get that URL back once it is gone: overwriting it moved
+    // every address and every transaction onto a third-party endpoint
+    // silently and permanently.
+    //
+    // s.rpcUrl / s.blockscoutUrl stay the live endpoints of the active
+    // network, so nothing that reads them changes. The invariant is that for
+    // the ACTIVE network those two fields are authoritative and the map entry
+    // may be stale (Settings writes the fields directly); for every other
+    // network the map is authoritative. Snapshotting the outgoing network
+    // here, before the switch, is what reconciles them.
+    if (!s.networkEndpoints) s.networkEndpoints = {};
+    s.networkEndpoints[s.networkId] = {
+        rpcUrl: s.rpcUrl,
+        blockscoutUrl: s.blockscoutUrl,
+    };
+    const remembered = s.networkEndpoints[net.id] || {};
+    s.networkId = net.id;
+    s.rpcUrl = remembered.rpcUrl || net.defaultRpcUrl;
+    s.blockscoutUrl = remembered.blockscoutUrl || net.defaultBlockscoutUrl;
+
+    // --- balance / refresh state ---
+    // Reset last-refresh timestamp so the next polling cycle
+    // triggers an immediate balance refresh on the new chain.
+    s.lastBalanceRefresh = 0;
+
+    // Clear per-address balances and token balances so stale data
+    // from the previous chain is never displayed while the first
+    // refresh on the new chain is in flight.
+    for (const wallet of s.wallets || []) {
+        for (const addr of wallet.addresses || []) {
+            addr.balance = "0";
+            addr.tokenBalances = [];
+        }
+    }
+
+    // --- chain-specific caches ---
+    // Token holder counts and fraud contract lists are
+    // chain-specific and must not carry over.
+    s.tokenHolderCache = {};
+    s.fraudContracts = [];
+
+    return net;
+}
+
+module.exports = { applyChainSwitchFields };

src/shared/ens.js

@@ -32,11 +32,11 @@ function setCache(address, name) {
     localStorage.setItem(key, JSON.stringify({ name, ts: Date.now() }));
 }
 
-async function resolveEnsName(address, rpcUrl) {
+async function resolveEnsName(address, rpcUrl, networkId) {
     const cached = getCached(address);
     if (cached !== undefined) return cached;
 
-    const provider = getProvider(rpcUrl);
+    const provider = getProvider(rpcUrl, networkId);
     try {
         const name = (await provider.lookupAddress(address)) || null;
         setCache(address, name);
@@ -48,11 +48,11 @@ async function resolveEnsName(address, rpcUrl) {
     }
 }
 
-async function resolveEnsNames(addresses, rpcUrl) {
+async function resolveEnsNames(addresses, rpcUrl, networkId) {
     const results = new Map();
     await Promise.all(
         addresses.map(async (addr) => {
-            results.set(addr, await resolveEnsName(addr, rpcUrl));
+            results.set(addr, await resolveEnsName(addr, rpcUrl, networkId));
         }),
     );
     return results;

src/shared/persistedState.js

@@ -0,0 +1,204 @@
+// The shape of the persisted profile, and the normalization every read of it
+// goes through. No singleton, no storage access, no browser API: just the
+// record definition and pure functions over it.
+//
+// Split out of state.js so that a context which must never touch the
+// module-level `state` singleton can still speak the same record format.
+// src/background/state.js is that context — the MV3 service worker never
+// populates the singleton, and every defect in
+// https://git.eeqj.de/sneak/AutistMask/issues/324 came from background code
+// reaching it anyway and being served DEFAULT_STATE.
+
+const { DEFAULT_RPC_URL, DEFAULT_BLOCKSCOUT_URL } = require("./constants");
+// Dependency-free constant module; safe to pull into a background bundle.
+const { RESTORABLE_VIEWS } = require("../popup/restorableViews");
+
+const DEFAULT_STATE = {
+    hasWallet: false,
+    wallets: [],
+    trackedTokens: [],
+    networkId: "mainnet",
+    rpcUrl: DEFAULT_RPC_URL,
+    blockscoutUrl: DEFAULT_BLOCKSCOUT_URL,
+    // Endpoints remembered per network: { [networkId]: { rpcUrl,
+    // blockscoutUrl } }. rpcUrl/blockscoutUrl above are the live endpoints
+    // of the active network; this is what the others are restored from
+    // when the active network changes. See applyChainSwitchFields().
+    networkEndpoints: {},
+    lastBalanceRefresh: 0,
+    activeAddress: null,
+    allowedSites: {},
+    deniedSites: {},
+    rememberSiteChoice: true,
+    showZeroBalanceTokens: true,
+    hideSpoofedSymbols: true,
+    hideLowHolderTokens: true,
+    hideFraudContracts: true,
+    hideDustTransactions: true,
+    dustThresholdGwei: 100000,
+    utcTimestamps: false,
+    fraudContracts: [],
+    tokenHolderCache: {},
+    theme: "system",
+    debugMode: false,
+};
+
+// Every field written to and read from the single "autistmask" storage key.
+// hasWallet is deliberately excluded from the diffing/merge logic in
+// state.js — like loadState() does, it is always derived from `wallets`,
+// never carried as an independent value.
+const PERSISTED_FIELDS = Object.keys(DEFAULT_STATE)
+    .filter((key) => key !== "hasWallet")
+    .concat([
+        "currentView",
+        "selectedWallet",
+        "selectedAddress",
+        "selectedToken",
+        "viewData",
+        "viewStack",
+    ]);
+
+// Keep only the leading run of stored views the popup is willing to render.
+//
+// restoreView() refuses to reopen ONTO a non-restorable view, but the stack
+// behind it used to be restored verbatim, so Back could walk onto a screen
+// whose content is deliberately never re-rendered — and "show-phrase" has no
+// Back control to leave by. Truncating at the first such entry instead of
+// splicing it out keeps the result a prefix of the stored stack, so every
+// surviving entry's Back target is exactly the one it had; splicing would
+// silently re-point the entry above the hole at a different screen.
+//
+// Filtering happens here on load rather than in saveState(): the live
+// in-session stack is legitimate (the screen really is rendered while the
+// popup is open), and only a load-side filter also repairs the stacks
+// already in storage, including ones written before a view left the set.
+function restorableStack(stored, currentView) {
+    // A stored stack that is missing or not an array keeps nothing, but it
+    // still goes through the never-empty rule below rather than returning
+    // early: otherwise a corrupt stack would depend on exactly the goBack()
+    // fallback that the explicit ["main"] exists in order not to depend on.
+    const source = Array.isArray(stored) ? stored : [];
+    const cut = source.findIndex((view) => !RESTORABLE_VIEWS.has(view));
+    const kept = cut === -1 ? source.slice() : source.slice(0, cut);
+    // A view restored below the root still needs somewhere for Back to go.
+    if (
+        kept.length === 0 &&
+        currentView !== "main" &&
+        RESTORABLE_VIEWS.has(currentView)
+    ) {
+        return ["main"];
+    }
+    return kept;
+}
+
+// Turn a raw stored (or missing) record into the full, defaulted shape
+// loadState() used to assign directly onto `state`. A pure function so that
+// saveState() can apply it too: the fields THIS page did not change still have
+// to come from storage in their loaded-and-normalized form, not as the raw
+// bytes another page (or an old release) left there — otherwise a legacy shape
+// a load has always self-healed in memory (a missing networkEndpoints map, an
+// out-of-range flag) is dropped right back into storage unfixed every time the
+// page that DID normalize it saves something unrelated, because that field's
+// value never "changed" for that page to notice.
+//
+// The result never shares structure with `saved`, so a caller may mutate it
+// freely: it is the detached record every per-call read in the background is
+// built on.
+function normalizePersisted(saved) {
+    saved = saved || {};
+    const out = {};
+    out.wallets = structuredClone(saved.wallets || []);
+    // Derived, never trusted verbatim off storage — see loadState().
+    out.hasWallet = out.wallets.length > 0;
+    out.trackedTokens = structuredClone(saved.trackedTokens || []);
+    out.networkId = saved.networkId || DEFAULT_STATE.networkId;
+    out.rpcUrl = saved.rpcUrl || DEFAULT_STATE.rpcUrl;
+    out.blockscoutUrl = saved.blockscoutUrl || DEFAULT_STATE.blockscoutUrl;
+    // An actual object is required, not merely a truthy non-array: the code
+    // below and applyChainSwitchFields() index and ASSIGN INTO this value, and
+    // assigning a property to a string or a number is a silent no-op in
+    // sloppy mode. Copied rather than referenced, nested pairs included, so
+    // normalizing never mutates the object a caller handed in.
+    const rawEndpoints =
+        typeof saved.networkEndpoints === "object" &&
+        saved.networkEndpoints !== null &&
+        !Array.isArray(saved.networkEndpoints)
+            ? saved.networkEndpoints
+            : {};
+    out.networkEndpoints = {};
+    for (const netId of Object.keys(rawEndpoints)) {
+        out.networkEndpoints[netId] = { ...rawEndpoints[netId] };
+    }
+    // A profile written before this map existed carries exactly one pair of
+    // endpoints, belonging to whatever network it was last on. Adopt it as
+    // that network's remembered pair, so a custom endpoint set on the old
+    // build is not lost by the first switch away and back.
+    if (!out.networkEndpoints[out.networkId]) {
+        out.networkEndpoints[out.networkId] = {
+            rpcUrl: out.rpcUrl,
+            blockscoutUrl: out.blockscoutUrl,
+        };
+    }
+    out.lastBalanceRefresh = saved.lastBalanceRefresh || 0;
+    out.activeAddress = saved.activeAddress || null;
+    out.allowedSites =
+        saved.allowedSites && !Array.isArray(saved.allowedSites)
+            ? structuredClone(saved.allowedSites)
+            : {};
+    out.deniedSites =
+        saved.deniedSites && !Array.isArray(saved.deniedSites)
+            ? structuredClone(saved.deniedSites)
+            : {};
+    out.rememberSiteChoice =
+        saved.rememberSiteChoice !== undefined
+            ? saved.rememberSiteChoice
+            : true;
+    out.showZeroBalanceTokens =
+        saved.showZeroBalanceTokens !== undefined
+            ? saved.showZeroBalanceTokens
+            : true;
+    // A profile written before this setting existed has no key for it. It
+    // is a safety filter, so absent must load as on, not as undefined.
+    out.hideSpoofedSymbols =
+        saved.hideSpoofedSymbols !== undefined
+            ? saved.hideSpoofedSymbols
+            : true;
+    out.hideLowHolderTokens =
+        saved.hideLowHolderTokens !== undefined
+            ? saved.hideLowHolderTokens
+            : true;
+    out.hideFraudContracts =
+        saved.hideFraudContracts !== undefined
+            ? saved.hideFraudContracts
+            : true;
+    out.hideDustTransactions =
+        saved.hideDustTransactions !== undefined
+            ? saved.hideDustTransactions
+            : true;
+    out.dustThresholdGwei =
+        saved.dustThresholdGwei !== undefined
+            ? saved.dustThresholdGwei
+            : 100000;
+    out.utcTimestamps =
+        saved.utcTimestamps !== undefined ? saved.utcTimestamps : false;
+    out.fraudContracts = structuredClone(saved.fraudContracts || []);
+    out.tokenHolderCache = structuredClone(saved.tokenHolderCache || {});
+    out.theme = saved.theme || "system";
+    out.debugMode = saved.debugMode !== undefined ? saved.debugMode : false;
+    out.currentView = saved.currentView || null;
+    out.selectedWallet =
+        saved.selectedWallet !== undefined ? saved.selectedWallet : null;
+    out.selectedAddress =
+        saved.selectedAddress !== undefined ? saved.selectedAddress : null;
+    out.selectedToken = saved.selectedToken || null;
+    out.viewData = structuredClone(saved.viewData || {});
+    out.viewStack = restorableStack(saved.viewStack, out.currentView);
+    return out;
+}
+
+module.exports = {
+    DEFAULT_STATE,
+    PERSISTED_FIELDS,
+    normalizePersisted,
+    restorableStack,
+};

src/shared/state.js

@@ -1,46 +1,36 @@
 // State management and extension storage persistence.
+//
+// The `state` export is a module-level singleton: ONE in-memory copy of the
+// profile per bundle, loaded once by loadState() and mutated in place from
+// then on. That is the popup's model — one page, one load at boot, one
+// lifetime.
+//
+// It is NOT the background's model, and the background must not reach it. The
+// MV3 service worker is torn down when idle and revived by the next message,
+// nothing loads state at module scope, and an unpopulated read used to hand
+// back DEFAULT_STATE with no complaint — five defects came out of that one
+// fact (https://git.eeqj.de/sneak/AutistMask/issues/324). Two things close it:
+// this module is unreachable from the background bundle (enforced by the
+// ESLint rule in eslint.config.js, and by the background having its own
+// per-call storage layer in src/background/state.js), and reading a persisted
+// field of the singleton before a load now THROWS instead of quietly serving
+// a default.
 
-const { DEFAULT_RPC_URL, DEFAULT_BLOCKSCOUT_URL } = require("./constants");
 const { networkById } = require("./networks");
-// Dependency-free constant module; safe to pull into a background bundle.
-const { RESTORABLE_VIEWS } = require("../popup/restorableViews");
+const {
+    DEFAULT_STATE,
+    PERSISTED_FIELDS,
+    normalizePersisted,
+} = require("./persistedState");
 
 const { storageGet, storageSet } = require("./browserApi");
 const { log } = require("./log");
 
-const DEFAULT_STATE = {
-    hasWallet: false,
-    wallets: [],
-    trackedTokens: [],
-    networkId: "mainnet",
-    rpcUrl: DEFAULT_RPC_URL,
-    blockscoutUrl: DEFAULT_BLOCKSCOUT_URL,
-    // Endpoints remembered per network: { [networkId]: { rpcUrl,
-    // blockscoutUrl } }. rpcUrl/blockscoutUrl above are the live endpoints
-    // of the active network; this is what the others are restored from
-    // when the active network changes. See onChainSwitch().
-    networkEndpoints: {},
-    lastBalanceRefresh: 0,
-    activeAddress: null,
-    allowedSites: {},
-    deniedSites: {},
-    rememberSiteChoice: true,
-    showZeroBalanceTokens: true,
-    hideSpoofedSymbols: true,
-    hideLowHolderTokens: true,
-    hideFraudContracts: true,
-    hideDustTransactions: true,
-    dustThresholdGwei: 100000,
-    utcTimestamps: false,
-    fraudContracts: [],
-    tokenHolderCache: {},
-    theme: "system",
-    debugMode: false,
-};
-
-const state = {
+// The live record the proxy below guards. Everything inside this module reads
+// and writes THIS object, never the proxy: the guard is for callers.
+const rawState = {
     ...DEFAULT_STATE,
-    // Its own object, not the one DEFAULT_STATE holds: onChainSwitch()
+    // Its own object, not the one DEFAULT_STATE holds: applyChainSwitchFields()
     // mutates this map in place, and a spread copies the reference.
     networkEndpoints: {},
     currentView: null,
@@ -51,161 +41,72 @@ const state = {
     viewStack: [],
 };
 
-// Keep only the leading run of stored views the popup is willing to render.
+// False until loadState() has completed in this bundle. Until then, a
+// persisted field that has not been assigned in this context cannot be READ:
+// see StateNotLoadedError.
+let loaded = false;
+
+// True once this context has assigned anything into the singleton.
 //
-// restoreView() refuses to reopen ONTO a non-restorable view, but the stack
-// behind it used to be restored verbatim, so Back could walk onto a screen
-// whose content is deliberately never re-rendered — and "show-phrase" has no
-// Back control to leave by. Truncating at the first such entry instead of
-// splicing it out keeps the result a prefix of the stored stack, so every
-// surviving entry's Back target is exactly the one it had; splicing would
-// silently re-point the entry above the hole at a different screen.
+// What the guard is for is a context that READS a profile nobody put there —
+// every one of the five defects was a pure read of an untouched singleton,
+// answered out of DEFAULT_STATE. A context that has written into it is
+// managing it deliberately (the popup does, via loadState() at boot and by
+// hand thereafter), and reading back what you yourself put there is not the
+// mistake being caught.
 //
-// Filtering happens here on load rather than in saveState(): the live
-// in-session stack is legitimate (the screen really is rendered while the
-// popup is open), and only a load-side filter also repairs the stacks
-// already in storage, including ones written before a view left the set.
-function restorableStack(stored, currentView) {
-    // A stored stack that is missing or not an array keeps nothing, but it
-    // still goes through the never-empty rule below rather than returning
-    // early: otherwise a corrupt stack would depend on exactly the goBack()
-    // fallback that the explicit ["main"] exists in order not to depend on.
-    const source = Array.isArray(stored) ? stored : [];
-    const cut = source.findIndex((view) => !RESTORABLE_VIEWS.has(view));
-    const kept = cut === -1 ? source.slice() : source.slice(0, cut);
-    // A view restored below the root still needs somewhere for Back to go.
-    if (
-        kept.length === 0 &&
-        currentView !== "main" &&
-        RESTORABLE_VIEWS.has(currentView)
-    ) {
-        return ["main"];
+// The cost of that is honest and worth naming: a context that writes one field
+// and then reads a different, untouched one is still served that field's
+// default. Nothing closes that here — what closes it for the background is
+// that the background cannot reach this module at all (eslint.config.js).
+let adopted = false;
+
+// Every field whose pre-load value would be a plausible-looking default rather
+// than the user's data. The view scratch fields are guarded too: currentView
+// and viewStack are persisted, and a save that carried their pre-load values
+// would overwrite a real stored stack with an empty one.
+const GUARDED_FIELDS = new Set(PERSISTED_FIELDS.concat(["hasWallet"]));
+
+class StateNotLoadedError extends Error {
+    constructor(field) {
+        super(
+            "state." +
+                field +
+                " was read before loadState(); this context has no profile" +
+                " loaded and must not be served DEFAULT_STATE",
+        );
+        this.name = "StateNotLoadedError";
     }
-    return kept;
 }
 
+// Loud, not defaulted. The whole defect class this guard closes looks exactly
+// like working code at the call site: the read succeeds, the value is
+// well-formed, and it describes a wallet that is not the user's.
+const state = new Proxy(rawState, {
+    get(target, prop, receiver) {
+        if (
+            !loaded &&
+            !adopted &&
+            typeof prop === "string" &&
+            GUARDED_FIELDS.has(prop)
+        ) {
+            throw new StateNotLoadedError(prop);
+        }
+        return Reflect.get(target, prop, receiver);
+    },
+    set(target, prop, value, receiver) {
+        if (typeof prop === "string" && GUARDED_FIELDS.has(prop)) {
+            adopted = true;
+        }
+        return Reflect.set(target, prop, value, receiver);
+    },
+});
+
 // Return the network configuration for the currently selected network.
 function currentNetwork() {
     return networkById(state.networkId);
 }
 
-// Every field written to and read from the single "autistmask" storage key.
-// hasWallet is deliberately excluded from the diffing/merge logic below —
-// like loadState() does, it is always derived from `wallets`, never carried
-// as an independent value.
-const PERSISTED_FIELDS = Object.keys(DEFAULT_STATE)
-    .filter((key) => key !== "hasWallet")
-    .concat([
-        "currentView",
-        "selectedWallet",
-        "selectedAddress",
-        "selectedToken",
-        "viewData",
-        "viewStack",
-    ]);
-
-// Turn a raw stored (or missing) record into the full, defaulted shape
-// loadState() used to assign directly onto `state`. Pulled out as a pure
-// function so saveState() can apply it too: the fields THIS page did not
-// change still have to come from storage in their loaded-and-normalized
-// form, not as the raw bytes another page (or an old release) left there —
-// otherwise a legacy shape a load has always self-healed in memory (a
-// missing networkEndpoints map, an out-of-range flag) is dropped right back
-// into storage unfixed every time the page that DID normalize it saves
-// something unrelated, because that field's value never "changed" for that
-// page to notice.
-function normalizePersisted(saved) {
-    saved = saved || {};
-    const out = {};
-    out.wallets = saved.wallets || [];
-    // Derived, never trusted verbatim off storage — see loadState().
-    out.hasWallet = out.wallets.length > 0;
-    out.trackedTokens = saved.trackedTokens || [];
-    out.networkId = saved.networkId || DEFAULT_STATE.networkId;
-    out.rpcUrl = saved.rpcUrl || DEFAULT_STATE.rpcUrl;
-    out.blockscoutUrl = saved.blockscoutUrl || DEFAULT_STATE.blockscoutUrl;
-    // An actual object is required, not merely a truthy non-array: the code
-    // below and onChainSwitch() index and ASSIGN INTO this value, and
-    // assigning a property to a string or a number is a silent no-op in
-    // sloppy mode. Copied rather than referenced, nested pairs included, so
-    // normalizing never mutates the object a caller handed in.
-    const rawEndpoints =
-        typeof saved.networkEndpoints === "object" &&
-        saved.networkEndpoints !== null &&
-        !Array.isArray(saved.networkEndpoints)
-            ? saved.networkEndpoints
-            : {};
-    out.networkEndpoints = {};
-    for (const netId of Object.keys(rawEndpoints)) {
-        out.networkEndpoints[netId] = { ...rawEndpoints[netId] };
-    }
-    // A profile written before this map existed carries exactly one pair of
-    // endpoints, belonging to whatever network it was last on. Adopt it as
-    // that network's remembered pair, so a custom endpoint set on the old
-    // build is not lost by the first switch away and back.
-    if (!out.networkEndpoints[out.networkId]) {
-        out.networkEndpoints[out.networkId] = {
-            rpcUrl: out.rpcUrl,
-            blockscoutUrl: out.blockscoutUrl,
-        };
-    }
-    out.lastBalanceRefresh = saved.lastBalanceRefresh || 0;
-    out.activeAddress = saved.activeAddress || null;
-    out.allowedSites =
-        saved.allowedSites && !Array.isArray(saved.allowedSites)
-            ? saved.allowedSites
-            : {};
-    out.deniedSites =
-        saved.deniedSites && !Array.isArray(saved.deniedSites)
-            ? saved.deniedSites
-            : {};
-    out.rememberSiteChoice =
-        saved.rememberSiteChoice !== undefined
-            ? saved.rememberSiteChoice
-            : true;
-    out.showZeroBalanceTokens =
-        saved.showZeroBalanceTokens !== undefined
-            ? saved.showZeroBalanceTokens
-            : true;
-    // A profile written before this setting existed has no key for it. It
-    // is a safety filter, so absent must load as on, not as undefined.
-    out.hideSpoofedSymbols =
-        saved.hideSpoofedSymbols !== undefined
-            ? saved.hideSpoofedSymbols
-            : true;
-    out.hideLowHolderTokens =
-        saved.hideLowHolderTokens !== undefined
-            ? saved.hideLowHolderTokens
-            : true;
-    out.hideFraudContracts =
-        saved.hideFraudContracts !== undefined
-            ? saved.hideFraudContracts
-            : true;
-    out.hideDustTransactions =
-        saved.hideDustTransactions !== undefined
-            ? saved.hideDustTransactions
-            : true;
-    out.dustThresholdGwei =
-        saved.dustThresholdGwei !== undefined
-            ? saved.dustThresholdGwei
-            : 100000;
-    out.utcTimestamps =
-        saved.utcTimestamps !== undefined ? saved.utcTimestamps : false;
-    out.fraudContracts = saved.fraudContracts || [];
-    out.tokenHolderCache = saved.tokenHolderCache || {};
-    out.theme = saved.theme || "system";
-    out.debugMode = saved.debugMode !== undefined ? saved.debugMode : false;
-    out.currentView = saved.currentView || null;
-    out.selectedWallet =
-        saved.selectedWallet !== undefined ? saved.selectedWallet : null;
-    out.selectedAddress =
-        saved.selectedAddress !== undefined ? saved.selectedAddress : null;
-    out.selectedToken = saved.selectedToken || null;
-    out.viewData = saved.viewData || {};
-    out.viewStack = restorableStack(saved.viewStack, out.currentView);
-    return out;
-}
-
 // The persisted fields as they stood at the end of this page's last
 // loadState() or saveState(). saveState() diffs the live state against this
 // to find only the fields THIS page actually changed.
@@ -217,7 +118,7 @@ let baseline = null;
 
 function snapshotPersisted() {
     const out = {};
-    for (const key of PERSISTED_FIELDS) out[key] = state[key];
+    for (const key of PERSISTED_FIELDS) out[key] = rawState[key];
     return out;
 }
 
@@ -374,11 +275,10 @@ function mergeWallet(base, ours, theirs) {
 }
 
 // Merge one address's leaf fields (balance, ensName, tokenBalances, ...).
-// tokenBalances is itself an array, but only backgroundRefresh() ever
-// writes it and always wholesale (refreshBalances() in
-// src/shared/balances.js), so there is no membership to reconcile within
-// it — it is a leaf like balance or ensName, not a list with its own
-// identity.
+// tokenBalances is itself an array, but only a balance refresh ever writes
+// it and always wholesale (refreshBalances() in src/shared/balances.js), so
+// there is no membership to reconcile within it — it is a leaf like balance
+// or ensName, not a list with its own identity.
 function mergeAddress(base, ours, theirs) {
     if (!base) return ours;
     const merged = { ...theirs };
@@ -425,12 +325,12 @@ function mergeMapByKey(base, ours, theirs, mergeLeaf) {
 }
 
 // allowedSites/deniedSites: { [address]: [hostname, ...] }. The hostname
-// list is itself membership, not a leaf — src/background/index.js pushes a
-// newly approved/denied hostname onto it in place, and the Settings "revoke"
-// button (src/popup/views/settings.js) filters a hostname out of it in
-// place, from a different page. Merge it the same way wallets are merged:
-// identity is the hostname itself, so a merged pair is always equal and
-// mergeItem is a no-op pick.
+// list is itself membership, not a leaf — the background appends a newly
+// approved/denied hostname to it, and the Settings "revoke" button
+// (src/popup/views/settings.js) filters a hostname out of it in place, from a
+// different page. Merge it the same way wallets are merged: identity is the
+// hostname itself, so a merged pair is always equal and mergeItem is a no-op
+// pick.
 function mergeHostnameList(base, ours, theirs) {
     return mergeListByIdentity(
         base,
@@ -445,14 +345,15 @@ function mergeSiteMap(base, ours, theirs) {
     return mergeMapByKey(base, ours, theirs, mergeHostnameList);
 }
 
-// networkEndpoints: { [networkId]: {rpcUrl, blockscoutUrl} }. onChainSwitch()
-// (src/shared/chainSwitch.js) writes state.networkEndpoints[networkId] in
-// place before saving. No code path ever removes a key from this map, so the
-// membership collision that matters for allowedSites/wallets (an add on one
-// page racing a delete on another) can't happen here — but two pages
-// switching to two different networks concurrently still race a whole-field
-// diff the same way, so it gets the same per-key merge for the leaf edit
-// case (e.g. Settings saving a custom RPC URL for the active network).
+// networkEndpoints: { [networkId]: {rpcUrl, blockscoutUrl} }.
+// applyChainSwitchFields() (src/shared/chainSwitchFields.js) writes
+// networkEndpoints[networkId] in place before saving. No code path ever
+// removes a key from this map, so the membership collision that matters for
+// allowedSites/wallets (an add on one page racing a delete on another) can't
+// happen here — but two pages switching to two different networks
+// concurrently still race a whole-field diff the same way, so it gets the same
+// per-key merge for the leaf edit case (e.g. Settings saving a custom RPC URL
+// for the active network).
 function mergeEndpointEntry(base, ours, theirs) {
     if (!base) return ours;
     const merged = { ...theirs };
@@ -468,12 +369,12 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 
 // Read-modify-write, merged per field, rather than one full-blob write.
 //
-// Every extension page (the toolbar popup, a dApp approval window, the
-// background's backgroundRefresh()) holds its own in-memory `state`, loaded
-// once, and showView() saves on every navigation. A full-blob write here
-// clobbers whatever a second page had written since — including, in the
-// worst case, an entire wallet and its encrypted secret with no attacker
-// and no unusual input (see the issue this fixes).
+// Every extension page (the toolbar popup, a dApp approval window) holds its
+// own in-memory `state`, loaded once, and showView() saves on every
+// navigation. A full-blob write here clobbers whatever a second page had
+// written since — including, in the worst case, an entire wallet and its
+// encrypted secret with no attacker and no unusual input (see the issue this
+// fixes).
 //
 // Only the fields this page actually changed — those that differ from
 // `baseline`, captured at the last loadState()/saveState() on this page —
@@ -482,28 +383,27 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 //
 // `wallets` is merged structurally (mergeListByIdentity(), by wallet
 // identity and then by address identity within each wallet), not as one
-// whole field: backgroundRefresh() mutates wallets IN PLACE (addr.balance /
+// whole field: a balance refresh mutates wallets IN PLACE (addr.balance /
 // ensName / tokenBalances, via refreshBalances()), so a whole-field diff
 // would mark all of `wallets` "changed" the moment any balance moved and
-// write back background's own copy — loaded before its multi-second network
+// write back that page's own copy — loaded before its multi-second network
 // round trip — clobbering a wallet another page added, or resurrecting one
-// another page deleted, in that window. Merging by identity lets
-// background's leaf changes and another page's membership changes
-// (add/delete a wallet or an address) apply independently instead of
-// colliding as the same field.
+// another page deleted, in that window. Merging by identity lets the leaf
+// changes and another page's membership changes (add/delete a wallet or an
+// address) apply independently instead of colliding as the same field.
 //
 // `allowedSites` and `deniedSites` get the same treatment (mergeSiteMap(),
 // by address key and then by hostname within each address's list), for the
-// identical reason: src/background/index.js pushes a newly
-// approved/denied hostname onto them in place, and the Settings "revoke"
-// button (src/popup/views/settings.js) filters one out in place, from a
-// different page. A whole-field diff here doesn't just lose data, it is a
-// security defect — a stale page's save can resurrect a just-revoked site
-// permission, or silently wipe a permission just granted elsewhere.
+// identical reason: the background appends a newly approved/denied hostname
+// to them, and the Settings "revoke" button (src/popup/views/settings.js)
+// filters one out in place, from a different page. A whole-field diff here
+// doesn't just lose data, it is a security defect — a stale page's save can
+// resurrect a just-revoked site permission, or silently wipe a permission just
+// granted elsewhere.
 //
 // `networkEndpoints` gets the same treatment too (mergeNetworkEndpoints(),
-// by network id), since onChainSwitch() writes into it in place; the value
-// per key is a small leaf object with no membership of its own; see the
+// by network id), since applyChainSwitchFields() writes into it in place; the
+// value per key is a small leaf object with no membership of its own; see the
 // comment at mergeEndpointEntry() for why the collision this closes is
 // milder than the other two.
 //
@@ -511,8 +411,8 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // `trackedTokens`/`fraudContracts`/`viewStack` are arrays of scalars with no
 // per-element identity to merge by; `tokenHolderCache` is a map shaped like
 // the ones above, but nothing in src/ ever writes an entry into it — it is
-// only ever reset wholesale to `{}` (onChainSwitch()) — so there is no
-// in-place mutation for a whole-field diff to collide with; `viewData` is
+// only ever reset wholesale to `{}` (applyChainSwitchFields()) — so there is
+// no in-place mutation for a whole-field diff to collide with; `viewData` is
 // this page's own UI scratch space, not data another page has any reason to
 // share membership of.
 //
@@ -539,7 +439,7 @@ async function saveStateOnce() {
     const result = await storageGet("autistmask");
     // Normalized, not raw: a field this page did not change still has to
     // come from storage in its loaded (self-healed) shape. See
-    // normalizePersisted() above.
+    // normalizePersisted() in persistedState.js.
     const fresh = normalizePersisted(result.autistmask);
 
     const merged = { ...fresh };
@@ -578,7 +478,7 @@ async function saveStateOnce() {
     // Derived from this page's own wallets, never adopted off the wire —
     // see loadState(). Everything else this page did not change is left
     // exactly as it stood; see the note above.
-    state.hasWallet = state.wallets.length > 0;
+    rawState.hasWallet = rawState.wallets.length > 0;
 
     baseline = structuredClone(snapshotPersisted());
 }
@@ -606,14 +506,21 @@ function saveState() {
 async function loadState() {
     const result = await storageGet("autistmask");
     if (result.autistmask) {
-        Object.assign(state, normalizePersisted(result.autistmask));
+        Object.assign(rawState, normalizePersisted(result.autistmask));
     }
-    // The point of comparison every saveState() on this page diffs against,
-    // whether storage had a profile or was empty. See PERSISTED_FIELDS above
-    // saveState() for why a reference here would be wrong.
+    // Whether storage had a profile or was empty, this context has now read
+    // it, and the defaults standing in for an empty profile are the right
+    // answer rather than a stand-in for one nobody looked for.
+    loaded = true;
+    // The point of comparison every saveState() on this page diffs against.
+    // See PERSISTED_FIELDS in persistedState.js for why a reference here
+    // would be wrong.
     baseline = structuredClone(snapshotPersisted());
 }
 
+// Through the guarded proxy, not rawState: a caller asking which address is
+// selected before anything was loaded gets the same loud failure it would get
+// reading the fields itself.
 function currentAddress() {
     if (state.selectedWallet === null || state.selectedAddress === null) {
         return null;
@@ -627,4 +534,5 @@ module.exports = {
     loadState,
     currentAddress,
     currentNetwork,
+    StateNotLoadedError,
 };

src/shared/uniswap.js

@@ -4,6 +4,10 @@
 const { Interface, AbiCoder, getBytes, formatUnits } = require("ethers");
 const { TOKEN_BY_ADDRESS } = require("./tokenList");
 const { truncateAmountNeverZero } = require("./amountDisplay");
+const {
+    resolveTokenDecimals,
+    unknownDecimalsAmount,
+} = require("./approvalAmount");
 
 const coder = AbiCoder.defaultAbiCoder();
 
@@ -44,13 +48,37 @@ function formatAmount(raw, decimals) {
     return truncateAmountNeverZero(formatUnits(raw, decimals));
 }
 
-function tokenInfo(address) {
+// `decimals` is null when nothing knows this token's scale. It is not
+// defaulted to 18: the swap lines land on the same approval screen as the
+// ERC-20 line, and a scale guessed there is what showed a 1,000 USDT swap as
+// 0.000000000001. `sources` is { trackedTokens, wallets }, shaped as they are
+// on `state`; resolveTokenDecimals() reads the bundled list, then those.
+function tokenInfo(address, sources) {
     if (!address || address === "0x0000000000000000000000000000000000000000") {
         return { symbol: "ETH", decimals: 18, address: null };
     }
     const t = TOKEN_BY_ADDRESS.get(address.toLowerCase());
-    if (t) return { symbol: t.symbol, decimals: t.decimals, address };
-    return { symbol: null, decimals: 18, address };
+    return {
+        symbol: t ? t.symbol : null,
+        decimals: resolveTokenDecimals(address, sources),
+        address,
+    };
+}
+
+// A swap amount line. With a scale it is the token quantity; with none it is
+// the base-unit integer with the unknown scale stated, the same refusal the
+// ERC-20 amount line makes, so the screen has one way of saying it. `display`
+// is the line on the screen, `raw` is what the status screens carry.
+function amountText(raw, info) {
+    if (info.decimals === null) {
+        const unknown = unknownDecimalsAmount(raw);
+        return { raw: unknown, display: unknown };
+    }
+    const formatted = formatAmount(raw, info.decimals);
+    return {
+        raw: formatted,
+        display: formatted + (info.symbol ? " " + info.symbol : ""),
+    };
 }
 
 // Decode PERMIT2_PERMIT (command 0x0a) input bytes.
@@ -323,7 +351,7 @@ function decodeV4Swap(input) {
 // Try to decode a Universal Router execute() call.
 // Returns { name, description, details } matching the format used by
 // the approval UI, or null if the calldata is not a recognised execute().
-function decode(data, toAddress) {
+function decode(data, toAddress, sources) {
     try {
         const parsed = ROUTER_IFACE.parseTransaction({ data });
         if (!parsed) return null;
@@ -416,10 +444,10 @@ function decode(data, toAddress) {
         }
 
         // Resolve token info
-        const inInfo = tokenInfo(inputToken);
+        const inInfo = tokenInfo(inputToken, sources);
         const outInfo = hasUnwrapWeth
             ? { symbol: "ETH", decimals: 18, address: null }
-            : tokenInfo(outputToken);
+            : tokenInfo(outputToken, sources);
 
         const inSymbol = inInfo.symbol;
         const outSymbol = outInfo.symbol;
@@ -456,16 +484,15 @@ function decode(data, toAddress) {
                 "0xffffffffffffffffffffffffffffffffffffffff",
             );
             const isUnlimited = inputAmount >= maxUint160;
-            const amountRaw = isUnlimited
-                ? "Unlimited"
-                : formatAmount(inputAmount, inInfo.decimals);
-            const amountStr = isUnlimited
-                ? "Unlimited"
-                : amountRaw + (inSymbol ? " " + inSymbol : "");
+            // An unbounded permit needs no scale to describe, so it is still
+            // named rather than refused.
+            const amount = isUnlimited
+                ? { raw: "Unlimited", display: "Unlimited" }
+                : amountText(inputAmount, inInfo);
             details.push({
                 label: "Amount",
-                value: amountStr,
-                rawValue: amountRaw,
+                value: amount.display,
+                rawValue: amount.raw,
             });
         }
 
@@ -486,10 +513,10 @@ function decode(data, toAddress) {
         }
 
         if (minOutput !== null && minOutput !== undefined) {
-            const minStr =
-                formatAmount(minOutput, outInfo.decimals) +
-                (outSymbol ? " " + outSymbol : "");
-            details.push({ label: "Min. received", value: minStr });
+            details.push({
+                label: "Min. received",
+                value: amountText(minOutput, outInfo).display,
+            });
         }
 
         details.push({ label: "Steps", value: commandNames.join(" \u2192 ") });

tests/alarms.test.js

@@ -8,6 +8,8 @@
 // A controllable clock plus a stubbed balance refresh, so a cadence test can
 // measure the interval between refreshes that actually happened rather than
 // asserting the interval someone intended.
+const { makeStorageStub } = require("./support/storageStub");
+
 let mockNow = 0;
 const mockBalanceRefreshAt = [];
 
@@ -247,32 +249,17 @@ describe("alarms module", () => {
 // Loads the background worker against stubbed browser APIs. The returned
 // store is the extension storage the worker sees, so a test can seed wallet
 // state and read back what the worker persisted.
+// The stub clones in both directions, as the real chrome.storage.local does,
+// and carries the latency simulation above on every operation. It used to
+// alias, which for this file meant the worker's in-memory wallets and the
+// "stored" ones were one object — see tests/support/storageStub.js.
 function loadBackground(initialStore = {}) {
-    const storageStore = initialStore;
+    const storage = makeStorageStub(initialStore, mockStorageTick);
     const alarmsStub = makeAlarmsStub();
     const listeners = { onInstalled: [], onStartup: [] };
     global.chrome = {
         alarms: alarmsStub,
-        storage: {
-            local: {
-                get: async (key) => {
-                    mockStorageTick();
-                    return Object.prototype.hasOwnProperty.call(
-                        storageStore,
-                        key,
-                    )
-                        ? { [key]: storageStore[key] }
-                        : {};
-                },
-                set: async (items) => {
-                    mockStorageTick();
-                    Object.assign(storageStore, items);
-                },
-                remove: async (key) => {
-                    delete storageStore[key];
-                },
-            },
-        },
+        storage,
         runtime: {
             onMessage: { addListener: jest.fn() },
             onConnect: { addListener: jest.fn() },
@@ -301,7 +288,7 @@ function loadBackground(initialStore = {}) {
     }));
     jest.resetModules();
     require("../src/background/index");
-    return { alarmsStub, listeners, store: storageStore };
+    return { alarmsStub, listeners, storage };
 }
 
 // Flush the promise chains the startup path and the alarm handlers run on.
@@ -476,12 +463,16 @@ describe("balance refresh steady-state cadence", () => {
         // The guard's actual job, and the reason it is shortened rather than
         // removed: while the popup is open it refreshes every 10 seconds and
         // stamps the same field, and the background job has nothing to add.
-        const store = seededStore();
-        const { alarmsStub } = loadBackground(store);
+        const { alarmsStub, storage } = loadBackground(seededStore());
         await settle();
 
         mockNow += PERIOD_MS;
-        store.autistmask.lastBalanceRefresh = mockNow - 10 * 1000;
+        // As the open popup's own refresh would leave it: written to storage,
+        // not poked into an object the worker happens to share.
+        storage.write("autistmask", {
+            ...storage.read("autistmask"),
+            lastBalanceRefresh: mockNow - 10 * 1000,
+        });
         alarmsStub.fire(BALANCE_REFRESH_ALARM);
         await settle();
 

tests/backgroundApproval.test.js

@@ -24,6 +24,7 @@ const { Network, Wallet } = require("ethers");
 // before any jest.doMock() of the module, so the copy assertions below check
 // what the user is actually shown.
 const { describeSigningFailure } = require("../src/shared/approvalVerify");
+const { makeStorageStub } = require("./support/storageStub");
 
 const SIGNER_KEY =
     "0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d";
@@ -137,22 +138,22 @@ function loadBackground(options) {
     jest.resetModules();
 
     const broadcastTransaction = jest.fn();
-    const loadState = jest.fn(opts.loadState || (async () => {}));
 
-    // The network the wallet is on, which the tests switch under a pending
-    // approval. The node the transaction is populated against is on the same
-    // one, as it would be: switching networks switches the RPC endpoint too.
-    let chain = MAINNET;
+    // The node the transaction is populated against is on whatever chain the
+    // stored profile says, as it would be: switching networks switches the RPC
+    // endpoint too. The background takes the network from storage per call —
+    // it holds no in-memory copy — so this reads the record rather than a
+    // variable the test keeps alongside it.
+    const chainOf = (networkId) =>
+        networkId === "sepolia" ? SEPOLIA : MAINNET;
 
-    jest.doMock("../src/shared/state", () => ({
-        state: { rpcUrl: "https://rpc.invalid", wallets: [] },
-        loadState,
-        saveState: jest.fn(async () => {}),
-        currentNetwork: () => ({ chainId: chain.hex }),
-    }));
     jest.doMock("../src/shared/balances", () => ({
-        getProvider: () =>
-            fakeProvider(broadcastTransaction, opts.provider, chain.num),
+        getProvider: (rpcUrl, networkId) =>
+            fakeProvider(
+                broadcastTransaction,
+                opts.provider,
+                chainOf(networkId).num,
+            ),
         refreshBalances: jest.fn(async () => {}),
     }));
     jest.doMock("../src/shared/phishingDomains", () => ({
@@ -177,12 +178,31 @@ function loadBackground(options) {
         wallets: [
             { name: "Wallet 1", type: "hd", addresses: [signer.address] },
         ],
+        networkId: "mainnet",
         rpcUrl: "https://rpc.invalid",
         activeAddress: signer.address,
         allowedSites: { [signer.address]: [HOSTNAME] },
         deniedSites: {},
     };
 
+    // The one wallet state there is. The background reads it per call and
+    // writes it read-modify-write; it holds no in-memory copy and cannot reach
+    // the shared singleton. Clones in both directions, as the real API does —
+    // the stub here used to hand back the live record and drop every write on
+    // the floor, so a test could neither see what was persisted nor be sure
+    // what it read had crossed the boundary
+    // (https://git.eeqj.de/sneak/AutistMask/issues/324).
+    const storage = makeStorageStub({ autistmask: persisted });
+
+    // A test that needs the state read itself to misbehave installs a hook —
+    // a stall, a throw — in place of the next reads. Armed after setup so
+    // that raising the approval is not what fails.
+    let storageGetHook = opts.storageGet || null;
+    const realGet = storage.local.get;
+    storage.local.get = jest.fn(async (key) =>
+        storageGetHook ? storageGetHook(key) : realGet(key),
+    );
+
     let messageListener = null;
     let windowRemovedListener = null;
     let connectListener = null;
@@ -194,15 +214,7 @@ function loadBackground(options) {
     const actionPopups = [];
 
     global.chrome = {
-        storage: {
-            local: {
-                get: jest.fn(
-                    opts.storageGet ||
-                        (async () => ({ autistmask: persisted })),
-                ),
-                set: jest.fn(async () => {}),
-            },
-        },
+        storage,
         runtime: {
             getURL: (path) => EXT_URL + path,
             onMessage: {
@@ -401,18 +413,32 @@ function loadBackground(options) {
         connectApproval,
         closeWindow,
         broadcastTransaction,
-        loadState,
         created,
         removed,
+        storage,
         // The user switching account in the toolbar popup, as the background
         // sees it: the persisted active address changes underneath a pending
         // approval.
         setActiveAddress: (address) => {
-            persisted.activeAddress = address;
+            storage.write("autistmask", {
+                ...storage.read("autistmask"),
+                activeAddress: address,
+            });
         },
-        // The user switching network in the toolbar popup.
+        // The user switching network in the toolbar popup. It moves the stored
+        // network and the endpoint together, as a real switch does.
         setNetwork: (network) => {
-            chain = network;
+            const networkId = network === SEPOLIA ? "sepolia" : "mainnet";
+            storage.write("autistmask", {
+                ...storage.read("autistmask"),
+                networkId,
+                rpcUrl: "https://rpc-" + networkId + ".invalid",
+            });
+        },
+        // Make the next state reads misbehave — stall, throw — without
+        // touching the reads that raised the approval. Pass null to restore.
+        setStateReadHook: (hook) => {
+            storageGetHook = hook;
         },
         fromPopup: { url: EXT_URL + "src/popup/index.html" },
     };
@@ -677,15 +703,16 @@ describe("one transaction approval at a time", () => {
     // page never — and holds the slot for the life of the worker with it.
     test("an approval whose window closed under a failed attempt is answered, and frees the next request", async () => {
         const stalled = deferred();
-        const bg = loadBackground({
-            loadState: async () => {
-                await stalled.promise;
-                throw new Error("The wallet data could not be read.");
-            },
-        });
+        const bg = loadBackground();
 
         const first = bg.requestTx();
         await settle();
+        // Armed only now: the approval was raised against a working state
+        // read, and it is the ATTEMPT's read that hangs and then fails.
+        bg.setStateReadHook(async () => {
+            await stalled.promise;
+            throw new Error("The wallet data could not be read.");
+        });
         bg.send(
             {
                 type: "AUTISTMASK_TX_RESPONSE",
@@ -709,6 +736,7 @@ describe("one transaction approval at a time", () => {
             error: { code: 4001, message: "User rejected the request." },
         });
 
+        bg.setStateReadHook(null);
         const second = bg.requestTx();
         await settle();
         expect(second.result()).toBeNull();
@@ -1226,19 +1254,18 @@ describe("what the approval is verified against", () => {
 // The interlock must not cost the retry the approval exists to allow.
 describe("the interlock releases a failed attempt", () => {
     test("a retryable failure before the broadcast leaves the approval usable", async () => {
-        let failNext = true;
-        const bg = loadBackground({
-            loadState: async () => {
-                if (failNext) {
-                    failNext = false;
-                    throw new Error("storage unavailable");
-                }
-            },
-        });
+        const bg = loadBackground();
         const pending = bg.requestTx();
         await settle();
         const id = pending.id();
 
+        // The attempt's state read fails once, then works: nothing was
+        // broadcast, so the approval must survive for the retry.
+        bg.setStateReadHook(() => {
+            bg.setStateReadHook(null);
+            throw new Error("storage unavailable");
+        });
+
         const first = bg.send(
             {
                 type: "AUTISTMASK_TX_RESPONSE",

tests/backgroundStateIsolation.test.js

@@ -0,0 +1,398 @@
+// What one background handler's state can do to another's while both are in
+// flight.
+//
+// The background used to read and write the module-level `state` singleton in
+// src/shared/state.js — one object, shared by every handler in the worker,
+// replaced wholesale by any loadState(). Two consequences, both covered here
+// and both from https://git.eeqj.de/sneak/AutistMask/issues/324:
+//
+//   - A transaction attempt captured the chain id at its loadState() and then
+//     read the ENDPOINT off the singleton several awaits later. A chain switch
+//     committed in that window moved the endpoint under an artifact already
+//     verified against the old chain, so it would have gone to the new chain's
+//     node — the very thing the verification exists to prevent.
+//
+//   - backgroundRefresh() handed the singleton's wallets to refreshBalances(),
+//     which mutates address objects in place across a multi-second network
+//     round trip. Any concurrent handler that loaded state replaced those
+//     objects, so the refreshed balances landed on detached ones and the save
+//     that followed persisted the pre-refresh values — while still stamping
+//     lastBalanceRefresh, suppressing the redo.
+//
+// Both use the real persistence path over a cloning storage stub. Nothing here
+// asserts the absence of a loadState() call; each asserts the OUTCOME, so it
+// holds against any implementation that gets the outcome right.
+
+const { Wallet } = require("ethers");
+const { networkById } = require("../src/shared/networks");
+const { makeStorageStub } = require("./support/storageStub");
+
+const SIGNER_KEY =
+    "0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d";
+const signer = new Wallet(SIGNER_KEY);
+const RECIPIENT = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+
+const CONNECTED_ORIGIN = "https://dapp.example";
+const CONNECTED_HOSTNAME = "dapp.example";
+const EXT_URL = "chrome-extension://autistmask/";
+
+const MAINNET = networkById("mainnet");
+const SEPOLIA = networkById("sepolia");
+
+const NONCE = 7;
+const REFRESHED_BALANCE = "1.5";
+
+// The transaction the background populates, and the artifact signed from it.
+// Its chain is a parameter because the whole subject here is a chain moving
+// under work already committed to one.
+function populated(chainId) {
+    return {
+        type: 2,
+        chainId,
+        nonce: NONCE,
+        gasLimit: 100000n,
+        maxFeePerGas: 2000000000n,
+        maxPriorityFeePerGas: 1000000000n,
+        to: RECIPIENT,
+        value: 10000000000000000n,
+        data: "0x",
+    };
+}
+
+function storedProfile(networkId) {
+    const net = networkById(networkId);
+    return {
+        hasWallet: true,
+        wallets: [
+            {
+                name: "Wallet 1",
+                type: "hd",
+                xpub: "xpub-1",
+                addresses: [
+                    {
+                        address: signer.address,
+                        balance: "0.0",
+                        tokenBalances: [],
+                    },
+                ],
+            },
+        ],
+        activeAddress: signer.address,
+        networkId,
+        rpcUrl: net.defaultRpcUrl,
+        blockscoutUrl: net.defaultBlockscoutUrl,
+        allowedSites: { [signer.address]: [CONNECTED_HOSTNAME] },
+        deniedSites: {},
+        trackedTokens: [],
+        lastBalanceRefresh: 0,
+    };
+}
+
+async function settle() {
+    for (let i = 0; i < 60; i++) await Promise.resolve();
+}
+
+function deferred() {
+    let resolve;
+    const promise = new Promise((res) => {
+        resolve = res;
+    });
+    return { promise, resolve };
+}
+
+afterEach(() => {
+    delete global.chrome;
+});
+
+// The background worker over a cloning storage stub, with the network and the
+// clock stubbed out. `opts.refreshBalances` replaces the balance refresh so a
+// test can hold one open across another handler's whole turn.
+function loadWorker(networkId, opts) {
+    const options = opts || {};
+    jest.resetModules();
+
+    // Every provider this worker constructs, in order, with the endpoint and
+    // the network id it was given. The subject of the first test is which pair
+    // reaches the broadcast.
+    const providers = [];
+    const broadcastTransaction = jest.fn(async () => ({ hash: "0xfeed" }));
+
+    jest.doMock("../src/shared/balances", () => ({
+        getProvider: (rpcUrl, networkId2) => {
+            const provider = {
+                rpcUrl,
+                networkId: networkId2,
+                broadcastTransaction,
+                getNetwork: async () => ({
+                    chainId: BigInt(networkById(networkId2).networkVersion),
+                }),
+                getTransactionCount: async () => NONCE,
+                estimateGas: async () => 100000n,
+                getFeeData: async () => ({
+                    gasPrice: 2000000000n,
+                    maxFeePerGas: 2000000000n,
+                    maxPriorityFeePerGas: 1000000000n,
+                }),
+            };
+            providers.push(provider);
+            return provider;
+        },
+        refreshBalances:
+            options.refreshBalances || jest.fn(async () => undefined),
+    }));
+    jest.doMock("../src/shared/phishingDomains", () => ({
+        isPhishingDomain: () => false,
+    }));
+    let alarmHandlers = {};
+    jest.doMock("../src/shared/alarms", () => ({
+        BALANCE_REFRESH_ALARM: "balance",
+        BALANCE_REFRESH_PERIOD_MINUTES: 1,
+        ensureRecurringAlarms: jest.fn(async () => {}),
+        registerAlarmHandlers: jest.fn((handlers) => {
+            alarmHandlers = handlers;
+        }),
+    }));
+
+    const storage = makeStorageStub({ autistmask: storedProfile(networkId) });
+    // A hook the tests use to suspend one handler mid-flight, so the other one
+    // runs entirely inside its window.
+    let getHook = null;
+    const realGet = storage.local.get;
+    storage.local.get = jest.fn(async (key) => {
+        if (getHook) await getHook();
+        return realGet(key);
+    });
+
+    let messageListener = null;
+    // Every popup URL the background opened. The approval id is in it, and
+    // that is how the popup learns which approval it is answering.
+    const createdUrls = [];
+    global.chrome = {
+        storage,
+        runtime: {
+            getURL: (path) => EXT_URL + path,
+            onMessage: {
+                addListener: (fn) => {
+                    messageListener = fn;
+                },
+            },
+            onConnect: { addListener: () => {} },
+            lastError: null,
+        },
+        windows: {
+            getLastFocused: (cb) => cb(null),
+            create: (createOpts, cb) => {
+                createdUrls.push(createOpts.url);
+                cb({ id: createdUrls.length });
+            },
+            remove: (id, cb) => {
+                if (cb) cb();
+            },
+            onRemoved: { addListener: () => {} },
+        },
+        tabs: {
+            query: (queryInfo, cb) => cb([{ id: 1 }]),
+            sendMessage: (tabId, message, cb) => {
+                if (cb) cb();
+            },
+        },
+        action: { setPopup: () => {} },
+    };
+
+    require("../src/background/index");
+
+    function send(msg, sender) {
+        let result = null;
+        const kept = messageListener(msg, sender, (r) => {
+            result = r;
+        });
+        return { kept, result: () => result };
+    }
+
+    function rpc(method, params, origin) {
+        return send(
+            { type: "AUTISTMASK_RPC", method, params },
+            { origin: origin || CONNECTED_ORIGIN },
+        );
+    }
+
+    return {
+        rpc,
+        send,
+        providers,
+        broadcastTransaction,
+        persisted: () => storage.read("autistmask"),
+        setGetHook: (hook) => {
+            getHook = hook;
+        },
+        fromPopup: { url: EXT_URL + "src/popup/index.html" },
+        fireBalanceAlarm: () => alarmHandlers.balance(),
+        lastApprovalId: () => {
+            const url = createdUrls[createdUrls.length - 1];
+            if (!url) return null;
+            return new URL(url, EXT_URL).searchParams.get("approval");
+        },
+    };
+}
+
+describe("a chain switch under a transaction already committed to a chain", () => {
+    // Item 4 of https://git.eeqj.de/sneak/AutistMask/issues/324.
+    //
+    // The artifact is verified against the chain read at the top of the
+    // attempt. Whatever endpoint it is then broadcast to has to be that same
+    // chain's — otherwise the wallet checks a transaction against Sepolia and
+    // sends it to a mainnet node. A connected site can switch the chain at any
+    // moment, including this one.
+    test("the artifact is broadcast to the endpoint of the chain it was verified against", async () => {
+        const bg = loadWorker("sepolia");
+
+        // Raise the approval, then find its id from the popup's own fetch.
+        bg.rpc("eth_sendTransaction", [
+            {
+                from: signer.address,
+                to: RECIPIENT,
+                value: "0x2386f26fc10000",
+                data: "0x",
+            },
+        ]);
+        await settle();
+
+        const id = bg.lastApprovalId();
+        expect(id).toBeTruthy();
+
+        // The popup signs what it was shown: Sepolia.
+        const rawSignedTx = await signer.signTransaction(
+            populated(Number(SEPOLIA.networkVersion)),
+        );
+
+        // A connected site switches the chain while the attempt is running,
+        // and the switch is committed to storage in full before the attempt
+        // goes any further.
+        //
+        // It is fired from inside the attempt's SECOND state read, because
+        // that is where the window used to be: the chain id was captured at
+        // the first read and the endpoint was taken off the singleton several
+        // awaits later, so a switch landing between them moved the endpoint
+        // under an artifact already verified against the old chain. An
+        // implementation that takes both from one read has no second read for
+        // this to fire on, and the switch below runs after the attempt is
+        // done instead — which is the point.
+        let reads = 0;
+        let switched = null;
+        const doSwitch = async () => {
+            switched = bg.rpc("wallet_switchEthereumChain", [
+                { chainId: MAINNET.chainId },
+            ]);
+            await settle();
+        };
+        bg.setGetHook(async () => {
+            reads++;
+            if (reads !== 2) return;
+            bg.setGetHook(null);
+            await doSwitch();
+        });
+
+        const attempt = bg.send(
+            {
+                type: "AUTISTMASK_TX_RESPONSE",
+                id,
+                approved: true,
+                rawSignedTx,
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+
+        bg.setGetHook(null);
+        if (!switched) await doSwitch();
+        expect(switched.result()).toEqual({ result: null });
+        expect(bg.persisted().networkId).toBe("mainnet");
+        await settle();
+
+        // It went out, and it went out to Sepolia's node — the chain the
+        // artifact was verified against. Reading the endpoint separately from
+        // the chain id put mainnet's here.
+        expect(attempt.result()).toEqual({ txHash: "0xfeed" });
+        expect(bg.broadcastTransaction).toHaveBeenCalledTimes(1);
+        const used = bg.providers[bg.providers.length - 1];
+        expect(used.rpcUrl).toBe(SEPOLIA.defaultRpcUrl);
+        expect(used.networkId).toBe("sepolia");
+    });
+});
+
+describe("a balance refresh under another handler's state read", () => {
+    // Item 5 of https://git.eeqj.de/sneak/AutistMask/issues/324.
+    //
+    // The trigger is a same-chain wallet_switchEthereumChain from a connected
+    // site: it answers { result: null } and changes nothing, so the ONLY thing
+    // it can do to the refresh is what its state read does. On the singleton
+    // that read replaced state.wallets, detaching the objects the refresh was
+    // mutating.
+    test("a chain read arriving mid-refresh does not discard the refresh", async () => {
+        const roundTrip = deferred();
+        const reachedNetwork = deferred();
+
+        const bg = loadWorker("sepolia", {
+            refreshBalances: async (wallets) => {
+                reachedNetwork.resolve();
+                await roundTrip.promise;
+                // In place, on the objects handed in — as balances.js does.
+                wallets[0].addresses[0].balance = REFRESHED_BALANCE;
+            },
+        });
+
+        const refresh = bg.fireBalanceAlarm();
+        await reachedNetwork.promise;
+
+        const answered = bg.rpc("wallet_switchEthereumChain", [
+            { chainId: SEPOLIA.chainId },
+        ]);
+        await settle();
+        expect(answered.result()).toEqual({ result: null });
+
+        roundTrip.resolve();
+        await refresh;
+
+        expect(bg.persisted().wallets[0].addresses[0].balance).toBe(
+            REFRESHED_BALANCE,
+        );
+        expect(bg.persisted().lastBalanceRefresh).toBeGreaterThan(0);
+    });
+
+    // The other half of "does not publish a shared object": a wallet added
+    // while the refresh was in flight must survive the refresh's own write.
+    test("a wallet added mid-refresh survives the refresh's write", async () => {
+        const roundTrip = deferred();
+        const reachedNetwork = deferred();
+
+        const bg = loadWorker("sepolia", {
+            refreshBalances: async (wallets) => {
+                reachedNetwork.resolve();
+                await roundTrip.promise;
+                wallets[0].addresses[0].balance = REFRESHED_BALANCE;
+            },
+        });
+
+        const refresh = bg.fireBalanceAlarm();
+        await reachedNetwork.promise;
+
+        // Another extension page adds a wallet while the round trip is out.
+        const during = bg.persisted();
+        during.wallets.push({
+            name: "Wallet 2",
+            type: "hd",
+            xpub: "xpub-2",
+            addresses: [
+                { address: RECIPIENT, balance: "0.0", tokenBalances: [] },
+            ],
+        });
+        global.chrome.storage.write("autistmask", during);
+
+        roundTrip.resolve();
+        await refresh;
+
+        const after = bg.persisted();
+        expect(after.wallets).toHaveLength(2);
+        expect(after.wallets[0].addresses[0].balance).toBe(REFRESHED_BALANCE);
+    });
+});

tests/backgroundStateLintRule.test.js

@@ -0,0 +1,235 @@
+// The lint rule that keeps src/shared/state.js out of the background bundle
+// (script/lib/eslint/noStateSingletonInBackground.js).
+//
+// Five defects, one of which destroyed a wallet, came from background code
+// reaching that singleton, and each point fix created the next site
+// (https://git.eeqj.de/sneak/AutistMask/issues/324).
+//
+// What this file does NOT do is establish that the singleton cannot reach the
+// background bundle. That is build.js's FORBIDDEN_INPUTS assertion, which reads
+// esbuild's metafile and so cannot be evaded by a syntax a matcher does not
+// know. The rule under test here is fast local feedback in front of that, and
+// these cases pin the shapes it is known to catch, so a regression in the
+// matcher is a failing test rather than a quietly narrower rule.
+//
+// Every shape below was measured against a real `make build`: each one puts
+// state.js in the shipped background bundles, and each one was invisible to
+// some earlier revision of the matcher — the quoted-only regex missed the
+// backtick, the dynamic import and the `from` clause; its successor missed a
+// comment inside the call and a directory resolved through package.json `main`.
+//
+// NOT covered, deliberately: a computed specifier such as
+// `require("../shared/" + "state")`. esbuild cannot resolve that statically
+// either, so it never reaches the bundle — there is nothing to block.
+
+const fs = require("fs");
+const os = require("os");
+const path = require("path");
+const { Linter } = require("eslint");
+
+const plugin = require("../script/lib/eslint/noStateSingletonInBackground");
+
+const RULE = "background/no-state-singleton-in-background";
+
+// The three files a fixture tree always has. `src/background/index.js` is
+// supplied per case; the other two stand in for the real modules.
+const SHARED_STATE = "const state = {};\nmodule.exports = { state };\n";
+const SHARED_HOP =
+    "// A shared module the background legitimately imports.\n" +
+    "module.exports = { applyChainSwitchFields() {} };\n";
+
+let roots = [];
+
+function fixture(files) {
+    const root = fs.realpathSync(
+        fs.mkdtempSync(path.join(os.tmpdir(), "autistmask-state-rule-")),
+    );
+    roots.push(root);
+    const tree = {
+        "src/shared/state.js": SHARED_STATE,
+        "src/shared/chainSwitchFields.js": SHARED_HOP,
+        ...files,
+    };
+    for (const [rel, source] of Object.entries(tree)) {
+        const abs = path.join(root, rel);
+        fs.mkdirSync(path.dirname(abs), { recursive: true });
+        fs.writeFileSync(abs, source);
+    }
+    return root;
+}
+
+// Run the rule exactly as eslint.config.js runs it, over a real tree: the walk
+// reads its sources from disk, so a virtual RuleTester would not exercise it.
+// `sourceType` is the fixture's own, not the rule's business: the walk is
+// textual and never parses the files it follows. The two ESM cases below pass
+// "module" only so espree can parse the fixture at all — in this repo those
+// shapes are also a parse error under the commonjs config, but the rule must
+// not be left depending on that.
+function lintBackground(root, { sourceType = "commonjs" } = {}) {
+    const file = path.join(root, "src/background/index.js");
+    const linter = new Linter({ cwd: root });
+    return linter.verify(
+        fs.readFileSync(file, "utf8"),
+        {
+            plugins: { background: plugin },
+            languageOptions: { ecmaVersion: 2024, sourceType },
+            rules: { [RULE]: "error" },
+        },
+        file,
+    );
+}
+
+function chainOf(messages) {
+    expect(messages).toHaveLength(1);
+    expect(messages[0].ruleId).toBe(RULE);
+    // "...singleton: <chain>. The MV3 worker..." — the chain is what the
+    // message exists to hand the reader, so assert on it rather than on the
+    // fact that something was reported.
+    return messages[0].message.split("singleton: ")[1].split(". The MV3")[0];
+}
+
+afterEach(() => {
+    for (const root of roots) fs.rmSync(root, { recursive: true, force: true });
+    roots = [];
+});
+
+describe("the specifier syntaxes the matcher is known to catch", () => {
+    test("a quoted require", () => {
+        const root = fixture({
+            "src/background/index.js":
+                'const { state } = require("../shared/state");\n' +
+                "module.exports = { state };\n",
+        });
+        expect(chainOf(lintBackground(root))).toBe(
+            "src/background/index.js -> src/shared/state.js",
+        );
+    });
+
+    test("a backtick require", () => {
+        const root = fixture({
+            "src/background/index.js":
+                "const { state } = require(`../shared/state`);\n" +
+                "module.exports = { state };\n",
+        });
+        expect(chainOf(lintBackground(root))).toBe(
+            "src/background/index.js -> src/shared/state.js",
+        );
+    });
+
+    test("a dynamic import inside an async function", () => {
+        const root = fixture({
+            "src/background/index.js":
+                "async function readState() {\n" +
+                '    const m = await import("../shared/state");\n' +
+                "    return m.state;\n" +
+                "}\n" +
+                "module.exports = { readState };\n",
+        });
+        expect(chainOf(lintBackground(root))).toBe(
+            "src/background/index.js -> src/shared/state.js",
+        );
+    });
+
+    test("a static import from-clause", () => {
+        const root = fixture({
+            "src/background/index.js":
+                'import { state } from "../shared/state";\n' +
+                "export { state };\n",
+        });
+        expect(chainOf(lintBackground(root, { sourceType: "module" }))).toBe(
+            "src/background/index.js -> src/shared/state.js",
+        );
+    });
+
+    // `import(/* webpackChunkName: "x" */ "./x")` is the standard bundler
+    // annotation idiom, and prettier leaves both of these exactly as written,
+    // so nothing else in the repo would object to them either.
+    test("a comment between the paren and the specifier", () => {
+        const root = fixture({
+            "src/background/index.js":
+                'globalThis.__probe = require(/* probe */ "../shared/state").state;\n',
+        });
+        expect(chainOf(lintBackground(root))).toBe(
+            "src/background/index.js -> src/shared/state.js",
+        );
+    });
+
+    test("a comment between the specifier and the closing paren", () => {
+        const root = fixture({
+            "src/background/index.js":
+                'globalThis.__probe = require("../shared/state" /* probe */).state;\n',
+        });
+        expect(chainOf(lintBackground(root))).toBe(
+            "src/background/index.js -> src/shared/state.js",
+        );
+    });
+
+    test("a bare side-effect import", () => {
+        const root = fixture({
+            "src/background/index.js": 'import "../shared/state";\n',
+        });
+        expect(chainOf(lintBackground(root, { sourceType: "module" }))).toBe(
+            "src/background/index.js -> src/shared/state.js",
+        );
+    });
+});
+
+describe("reachability, not just the direct specifier", () => {
+    // The shape a no-restricted-imports could never see: no background file
+    // names state.js, and the singleton is in the bundle anyway. In a backtick
+    // require, so this fails on the specifier widening as well as on the walk.
+    test("a two-hop re-export through a shared module", () => {
+        const root = fixture({
+            "src/background/index.js":
+                'const { applyChainSwitchFields } = require("../shared/chainSwitchFields");\n' +
+                "module.exports = { applyChainSwitchFields };\n",
+            "src/shared/chainSwitchFields.js":
+                SHARED_HOP +
+                "module.exports.state = require(`./state`).state;\n",
+        });
+        expect(chainOf(lintBackground(root))).toBe(
+            "src/background/index.js -> src/shared/chainSwitchFields.js" +
+                " -> src/shared/state.js",
+        );
+    });
+
+    // Resolution, not syntax: the specifier names a directory, and the file it
+    // resolves to is chosen by that directory's package.json `main`. A walk
+    // that only tries `<dir>/index.js` stops on a specifier it matched.
+    test("a directory resolved through its package.json main", () => {
+        const root = fixture({
+            "src/background/index.js":
+                'globalThis.__probe = require("../shared/probepkg").state;\n',
+            "src/shared/probepkg/package.json": '{"main": "./bridge.js"}\n',
+            "src/shared/probepkg/bridge.js":
+                'const { state } = require("../state");\n' +
+                "module.exports = { state };\n",
+        });
+        expect(chainOf(lintBackground(root))).toBe(
+            "src/background/index.js -> src/shared/probepkg/bridge.js" +
+                " -> src/shared/state.js",
+        );
+    });
+});
+
+describe("what the rule must not report", () => {
+    test("a background file that reaches only its own state layer", () => {
+        const root = fixture({
+            "src/background/index.js":
+                'const { getState } = require("./state");\n' +
+                'const { applyChainSwitchFields } = require("../shared/chainSwitchFields");\n' +
+                "module.exports = { getState, applyChainSwitchFields };\n",
+            "src/background/state.js":
+                "async function getState() {}\nmodule.exports = { getState };\n",
+        });
+        expect(lintBackground(root)).toEqual([]);
+    });
+
+    // The tree as it actually stands. This is the assertion that would catch a
+    // widened matcher that resolves something it should not: it runs the rule
+    // over the real background entrypoint, from the real repo root.
+    test("the repository's own background entrypoint", () => {
+        const root = path.resolve(__dirname, "..");
+        expect(lintBackground(root)).toEqual([]);
+    });
+});

tests/chainSwitchGate.test.js

@@ -8,10 +8,12 @@
 // broadcast — because an error code alone would not distinguish a gate from
 // a switch that happened and then reported a failure.
 //
-// The endpoint half of that issue lives in tests/networkEndpoints.test.js;
-// this file mocks the state module, which that one exercises for real.
+// The endpoint half of that issue lives in tests/networkEndpoints.test.js,
+// which covers the popup's chain switch; this file covers the background's,
+// which goes through storage rather than the shared state singleton.
 
 const { networkById } = require("../src/shared/networks");
+const { makeStorageStub } = require("./support/storageStub");
 
 const ADDRESS = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
 
@@ -51,29 +53,11 @@ afterEach(() => {
 // ---------------------------------------------------------------------------
 
 // Load the background worker against stubbed browser APIs, with the real
-// chain-switch module behind it, and return the handles to drive it. The
-// wallet state is a plain object so that a switch that DID happen is visible
-// as a mutation of it, and one that did not is visible as its absence.
+// chain-switch and persistence modules behind it, and return the handles to
+// drive it.
 function loadBackground() {
     jest.resetModules();
 
-    const walletState = {
-        networkId: "mainnet",
-        rpcUrl: CUSTOM_RPC,
-        blockscoutUrl: MAINNET.defaultBlockscoutUrl,
-        networkEndpoints: {},
-        wallets: walletFixture(),
-        lastBalanceRefresh: 1,
-        tokenHolderCache: {},
-        fraudContracts: [],
-    };
-
-    jest.doMock("../src/shared/state", () => ({
-        state: walletState,
-        loadState: jest.fn(async () => {}),
-        saveState: jest.fn(async () => {}),
-        currentNetwork: () => networkById(walletState.networkId),
-    }));
     jest.doMock("../src/shared/balances", () => ({
         getProvider: () => ({}),
         refreshBalances: jest.fn(async () => {}),
@@ -88,12 +72,24 @@ function loadBackground() {
         registerAlarmHandlers: jest.fn(),
     }));
 
+    // Storage is the only wallet state there is. The background reads and
+    // writes it per call — it holds no in-memory copy and cannot reach the
+    // shared singleton — so a switch that happened is visible here as a
+    // written record, and one that did not is visible as its absence.
     const persisted = {
+        networkId: "mainnet",
+        rpcUrl: CUSTOM_RPC,
+        blockscoutUrl: MAINNET.defaultBlockscoutUrl,
+        networkEndpoints: {},
         wallets: walletFixture(),
+        lastBalanceRefresh: 1,
+        tokenHolderCache: {},
+        fraudContracts: [],
         activeAddress: ADDRESS,
         allowedSites: { [ADDRESS]: [CONNECTED_HOSTNAME] },
         deniedSites: {},
     };
+    const storage = makeStorageStub({ autistmask: persisted });
 
     let messageListener = null;
     // Every message the background pushed at a content script. chainChanged
@@ -102,12 +98,7 @@ function loadBackground() {
     const toTabs = [];
 
     global.chrome = {
-        storage: {
-            local: {
-                get: jest.fn(async () => ({ autistmask: persisted })),
-                set: jest.fn(async () => {}),
-            },
-        },
+        storage,
         runtime: {
             getURL: (path) => "chrome-extension://autistmask/" + path,
             onMessage: {
@@ -157,7 +148,7 @@ function loadBackground() {
 
     return {
         switchChain,
-        walletState,
+        walletState: () => storage.read("autistmask"),
         chainChangedEvents: () =>
             toTabs.filter((m) => m.eventName === "chainChanged"),
     };
@@ -174,8 +165,8 @@ describe("wallet_switchEthereumChain is gated on the connection", () => {
         // The refusal has to be a refusal to ACT, not just an error string:
         // the wallet is still on mainnet, still on the user's own node, and
         // no page was told the chain moved.
-        expect(bg.walletState.networkId).toBe("mainnet");
-        expect(bg.walletState.rpcUrl).toBe(CUSTOM_RPC);
+        expect(bg.walletState().networkId).toBe("mainnet");
+        expect(bg.walletState().rpcUrl).toBe(CUSTOM_RPC);
         expect(bg.chainChangedEvents()).toEqual([]);
     });
 
@@ -201,7 +192,7 @@ describe("wallet_switchEthereumChain is gated on the connection", () => {
         const result = await bg.switchChain(SEPOLIA.chainId, CONNECTED_ORIGIN);
 
         expect(result).toEqual({ result: null });
-        expect(bg.walletState.networkId).toBe("sepolia");
+        expect(bg.walletState().networkId).toBe("sepolia");
         expect(bg.chainChangedEvents()).toEqual([
             {
                 type: "AUTISTMASK_EVENT",
@@ -217,16 +208,16 @@ describe("wallet_switchEthereumChain is gated on the connection", () => {
         const result = await bg.switchChain("0x89", CONNECTED_ORIGIN);
 
         expect(result.error.code).toBe(4902);
-        expect(bg.walletState.networkId).toBe("mainnet");
+        expect(bg.walletState().networkId).toBe("mainnet");
     });
 
     test("a switch by a connected origin keeps the user's endpoint", async () => {
         const bg = loadBackground();
 
         await bg.switchChain(SEPOLIA.chainId, CONNECTED_ORIGIN);
-        expect(bg.walletState.rpcUrl).toBe(SEPOLIA.defaultRpcUrl);
+        expect(bg.walletState().rpcUrl).toBe(SEPOLIA.defaultRpcUrl);
 
         await bg.switchChain(MAINNET.chainId, CONNECTED_ORIGIN);
-        expect(bg.walletState.rpcUrl).toBe(CUSTOM_RPC);
+        expect(bg.walletState().rpcUrl).toBe(CUSTOM_RPC);
     });
 });

tests/coldWorkerChainSwitch.test.js

@@ -16,6 +16,7 @@
 // first, so neither can see this.
 
 const { networkById } = require("../src/shared/networks");
+const { makeStorageStub } = require("./support/storageStub");
 
 const ADDRESS = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
 
@@ -64,9 +65,12 @@ afterEach(() => {
     delete global.chrome;
 });
 
-// Load the background worker with the real state and chain-switch modules
-// behind it, over a storage stub that actually keeps what is written — a
-// wipe is only observable against storage that remembers.
+// Load the background worker with the real chain-switch and persistence
+// modules behind it, over a storage stub that actually keeps what is written —
+// a wipe is only observable against storage that remembers — and that clones
+// in both directions, as the real API does. It used to alias, so the record
+// the worker held and the "stored" one were a single object; see
+// tests/support/storageStub.js.
 function loadColdWorker(networkId) {
     jest.resetModules();
 
@@ -84,20 +88,13 @@ function loadColdWorker(networkId) {
         registerAlarmHandlers: jest.fn(),
     }));
 
-    const store = { autistmask: storedProfile(networkId) };
+    const storage = makeStorageStub({ autistmask: storedProfile(networkId) });
 
     let messageListener = null;
     const toTabs = [];
 
     global.chrome = {
-        storage: {
-            local: {
-                get: jest.fn(async () => ({ autistmask: store.autistmask })),
-                set: jest.fn(async (items) => {
-                    store.autistmask = items.autistmask;
-                }),
-            },
-        },
+        storage,
         runtime: {
             getURL: (path) => "chrome-extension://autistmask/" + path,
             onMessage: {
@@ -147,7 +144,7 @@ function loadColdWorker(networkId) {
 
     return {
         switchChain,
-        persisted: () => store.autistmask,
+        persisted: () => storage.read("autistmask"),
         chainChangedEvents: () =>
             toTabs.filter((m) => m.eventName === "chainChanged"),
     };

tests/coldWorkerSendTransaction.test.js

@@ -0,0 +1,279 @@
+// Which chain a dApp transaction is PREPARED for on a worker that has not
+// loaded state.
+//
+// The MV3 service worker is terminated when idle — roughly 30 seconds, which
+// is its normal condition — and revived by the page's own message. Nothing
+// loads state at module scope, so handleSendTransaction() used to build its
+// provider with `getProvider(await getRpcUrl())`: the endpoint came from
+// storage and was right, and the static network hint was omitted, so
+// src/shared/balances.js fell back to currentNetwork() — the unpopulated
+// singleton — and answered mainnet. ethers then fixed `chainId` at 0x1.
+//
+// The transaction was not sent on the wrong chain: verifySignedTx() compares
+// the artifact against the selected chain and refused it. So the guard held
+// and the feature did not — a user on any non-mainnet network could not send
+// from a dApp at all, and the error described the symptom
+// (https://git.eeqj.de/sneak/AutistMask/issues/320).
+//
+// This drives the real balances module and the real approval preparation and
+// verification. Only ethers' JsonRpcProvider is replaced, so the static
+// network hint getProvider() computes is the hint the population sees.
+
+const { Network, Wallet, Transaction } = require("ethers");
+const { networkById } = require("../src/shared/networks");
+const { makeStorageStub } = require("./support/storageStub");
+
+const SIGNER_KEY =
+    "0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d";
+const signer = new Wallet(SIGNER_KEY);
+const RECIPIENT = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+
+const CONNECTED_ORIGIN = "https://dapp.example";
+const CONNECTED_HOSTNAME = "dapp.example";
+const EXT_URL = "chrome-extension://autistmask/";
+
+const SEPOLIA = networkById("sepolia");
+const MAINNET = networkById("mainnet");
+
+const NONCE = 7;
+const TX_HASH = "0xfeed";
+
+const TX_PARAMS = {
+    from: signer.address,
+    to: RECIPIENT,
+    value: "0x2386f26fc10000",
+    data: "0x",
+};
+
+function storedProfile(networkId) {
+    const net = networkById(networkId);
+    return {
+        hasWallet: true,
+        wallets: [
+            {
+                name: "Wallet 1",
+                type: "hd",
+                xpub: "xpub-1",
+                addresses: [
+                    {
+                        address: signer.address,
+                        balance: "0.0",
+                        tokenBalances: [],
+                    },
+                ],
+            },
+        ],
+        activeAddress: signer.address,
+        networkId,
+        rpcUrl: net.defaultRpcUrl,
+        blockscoutUrl: net.defaultBlockscoutUrl,
+        allowedSites: { [signer.address]: [CONNECTED_HOSTNAME] },
+        deniedSites: {},
+        trackedTokens: [],
+    };
+}
+
+async function settle() {
+    for (let i = 0; i < 60; i++) await Promise.resolve();
+}
+
+afterEach(() => {
+    delete global.chrome;
+});
+
+// A worker whose only wallet state is what is in storage, with ethers'
+// JsonRpcProvider replaced by a stub that answers out of the static network it
+// was constructed with — which is exactly what a real staticNetwork provider
+// does, and what makes the chain id on the approval screen observable here.
+function loadColdWorker(networkId) {
+    jest.resetModules();
+
+    const constructed = [];
+    const broadcast = [];
+
+    jest.doMock("ethers", () => {
+        const actual = jest.requireActual("ethers");
+        class StubJsonRpcProvider {
+            constructor(url, network) {
+                this._network = network;
+                constructed.push({ url, network });
+            }
+            async getNetwork() {
+                return this._network;
+            }
+            async getTransactionCount() {
+                return NONCE;
+            }
+            async estimateGas() {
+                return 100000n;
+            }
+            async getFeeData() {
+                return {
+                    gasPrice: 2000000000n,
+                    maxFeePerGas: 2000000000n,
+                    maxPriorityFeePerGas: 1000000000n,
+                };
+            }
+            async broadcastTransaction(raw) {
+                broadcast.push(raw);
+                return { hash: TX_HASH };
+            }
+        }
+        return { ...actual, JsonRpcProvider: StubJsonRpcProvider };
+    });
+    jest.doMock("../src/shared/phishingDomains", () => ({
+        isPhishingDomain: () => false,
+    }));
+    jest.doMock("../src/shared/alarms", () => ({
+        BALANCE_REFRESH_ALARM: "balance",
+        BALANCE_REFRESH_PERIOD_MINUTES: 1,
+        ensureRecurringAlarms: jest.fn(async () => {}),
+        registerAlarmHandlers: jest.fn(),
+    }));
+
+    const storage = makeStorageStub({ autistmask: storedProfile(networkId) });
+
+    let messageListener = null;
+    const createdUrls = [];
+
+    global.chrome = {
+        storage,
+        runtime: {
+            getURL: (path) => EXT_URL + path,
+            onMessage: {
+                addListener: (fn) => {
+                    messageListener = fn;
+                },
+            },
+            onConnect: { addListener: () => {} },
+            lastError: null,
+        },
+        windows: {
+            getLastFocused: (cb) => cb(null),
+            create: (opts, cb) => {
+                createdUrls.push(opts.url);
+                cb({ id: createdUrls.length });
+            },
+            remove: (id, cb) => {
+                if (cb) cb();
+            },
+            onRemoved: { addListener: () => {} },
+        },
+        tabs: {
+            query: (queryInfo, cb) => cb([{ id: 1 }]),
+            sendMessage: (tabId, message, cb) => {
+                if (cb) cb();
+            },
+        },
+        action: { setPopup: () => {} },
+    };
+
+    require("../src/background/index");
+
+    function send(msg, sender) {
+        let result = null;
+        messageListener(msg, sender, (r) => {
+            result = r;
+        });
+        return () => result;
+    }
+
+    return {
+        send,
+        constructed,
+        broadcast,
+        fromPopup: { url: EXT_URL + "src/popup/index.html" },
+        // The first message this worker ever sees, as the injected provider
+        // sends it.
+        sendTransaction: () =>
+            send(
+                {
+                    type: "AUTISTMASK_RPC",
+                    method: "eth_sendTransaction",
+                    params: [TX_PARAMS],
+                },
+                { origin: CONNECTED_ORIGIN },
+            ),
+        approvalId: () => {
+            const url = createdUrls[createdUrls.length - 1];
+            return url
+                ? new URL(url, EXT_URL).searchParams.get("approval")
+                : null;
+        },
+    };
+}
+
+// What the approval window does: fetch the approval and sign the transaction
+// it was handed, exactly as given.
+function signApproved(approvedTx) {
+    const tx = {};
+    for (const [key, value] of Object.entries(approvedTx)) {
+        if (key === "from") continue;
+        tx[key] = value;
+    }
+    return signer.signTransaction(tx);
+}
+
+describe("a dApp transaction prepared by a worker that never loaded state", () => {
+    test("a cold send on Sepolia reaches the approval screen and goes out", async () => {
+        const bg = loadColdWorker("sepolia");
+
+        const answer = bg.sendTransaction();
+        await settle();
+
+        // The provider was built for Sepolia, endpoint and static hint
+        // together. Omitting the hint made this mainnet.
+        expect(bg.constructed).toHaveLength(1);
+        expect(bg.constructed[0].url).toBe(SEPOLIA.defaultRpcUrl);
+        expect(bg.constructed[0].network.chainId).toBe(
+            Network.from("sepolia").chainId,
+        );
+
+        // So the approval the user is shown is a Sepolia transaction.
+        const id = bg.approvalId();
+        expect(id).toBeTruthy();
+        const approval = bg.send(
+            { type: "AUTISTMASK_GET_APPROVAL", id },
+            { url: bg.fromPopup.url },
+        )();
+        expect(approval.type).toBe("tx");
+        expect(approval.approvedTx.chainId).toBe(SEPOLIA.chainId);
+
+        // And it survives the wallet's own verification, which is where a
+        // 0x1-stamped artifact was refused as "for a different network".
+        const rawSignedTx = await signApproved(approval.approvedTx);
+        const response = bg.send(
+            {
+                type: "AUTISTMASK_TX_RESPONSE",
+                id,
+                approved: true,
+                rawSignedTx,
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+
+        expect(response()).toEqual({ txHash: TX_HASH });
+        expect(bg.broadcast).toEqual([rawSignedTx]);
+        expect(Number(Transaction.from(rawSignedTx).chainId)).toBe(
+            Number(SEPOLIA.networkVersion),
+        );
+        expect(answer()).toEqual({ result: TX_HASH });
+    });
+
+    test("a cold send on mainnet is prepared for mainnet", async () => {
+        // The stored value and the old fallback agree here, so this case
+        // cannot catch the defect; it is what keeps the fix from being a swap.
+        const bg = loadColdWorker("mainnet");
+
+        bg.sendTransaction();
+        await settle();
+
+        expect(bg.constructed[0].url).toBe(MAINNET.defaultRpcUrl);
+        const approval = bg.send(
+            { type: "AUTISTMASK_GET_APPROVAL", id: bg.approvalId() },
+            { url: bg.fromPopup.url },
+        )();
+        expect(approval.approvedTx.chainId).toBe(MAINNET.chainId);
+    });
+});

tests/deleteAddress.test.js

@@ -19,6 +19,14 @@ const {
     balanceWarningHtml,
 } = require("../src/popup/views/deleteAddress");
 const { prices, clearPrices } = require("../src/shared/prices");
+const { state } = require("../src/shared/state");
+
+// The screen prices holdings, and pricing asks which chain it is on. Reading
+// the singleton's network before anything loaded it now throws rather than
+// answering mainnet by default
+// (https://git.eeqj.de/sneak/AutistMask/issues/324), so the network this
+// fixture is on is stated instead of assumed.
+state.networkId = "mainnet";
 
 const USDC = "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48";
 

tests/deleteWalletLostPassword.test.js

@@ -13,13 +13,15 @@
 // never persisting it looks identical from `state`, and a build that never
 // wrote at all would pass a check that only reads `state` back.
 //
-// That makes the storage stub load-bearing, so it is a real store that
-// structured-clones on both `set` and `get`. A stub whose `get` hands back
-// the same object its `set` was given aliases the caller's own array: the
-// test then reads its own in-memory mutation and calls it persistence, and
-// passes against a build that persists nothing (see issue #324). The
-// aliasing is closed off explicitly by the first test below rather than
-// left as an assumption about `structuredClone`.
+// That makes the storage stub load-bearing, so it is the shared one from
+// tests/support/storageStub.js, a real store that structured-clones on both
+// `set` and `get`. A stub whose `get` hands back the same object its `set`
+// was given aliases the caller's own array: the test then reads its own
+// in-memory mutation and calls it persistence, and passes against a build
+// that persists nothing
+// (https://git.eeqj.de/sneak/AutistMask/issues/324). The aliasing is closed
+// off explicitly by the first test below rather than left as an assumption
+// about `structuredClone`.
 //
 // The view is driven against a minimal DOM stub, in the same shape as
 // tests/exportPrivkey.test.js: the module reads and writes named nodes and
@@ -34,6 +36,7 @@ jest.mock("../src/shared/vault", () => ({
 }));
 
 const { RESTORABLE_VIEWS } = require("../src/popup/restorableViews");
+const { makeStorageStub } = require("./support/storageStub");
 
 const VIEW = "delete-wallet-lost-password";
 
@@ -94,35 +97,6 @@ function makeDocument() {
     };
 }
 
-// --------------------------------------------------------- storage stub
-
-// A store that behaves the way `chrome.storage.local` does: what goes in is
-// serialized, so the caller keeps no handle on what came to rest there, and
-// what comes out is a fresh object the caller may mutate freely.
-function makeStorage() {
-    let store = {};
-    return {
-        get: async (keys) => {
-            const wanted =
-                keys === undefined || keys === null
-                    ? Object.keys(store)
-                    : [].concat(keys);
-            const out = {};
-            for (const key of wanted) {
-                if (key in store) out[key] = structuredClone(store[key]);
-            }
-            return out;
-        },
-        set: async (items) => {
-            for (const [key, value] of Object.entries(items)) {
-                store[key] = structuredClone(value);
-            }
-        },
-        // Test-only: what the extension would find on a cold start.
-        _raw: () => structuredClone(store),
-    };
-}
-
 // ------------------------------------------------------------ harness
 
 function wallet(name, secret, addresses) {
@@ -144,10 +118,10 @@ function load() {
     jest.resetModules();
     mockSettingsShow.mockClear();
 
-    const storage = makeStorage();
+    const storage = makeStorageStub();
     const sent = [];
     globalThis.chrome = {
-        storage: { local: storage },
+        storage: { local: storage.local },
         runtime: { sendMessage: (msg) => sent.push(msg) },
     };
     globalThis.document = makeDocument();
@@ -205,7 +179,7 @@ async function openLostPassword(deleteWallet, walletIdx) {
 // every other test in this file against a build that never writes.
 describe("the storage stub", () => {
     test("does not hand back the object it was given", async () => {
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         const written = { wallets: [{ name: "Wallet 1" }] };
 
         await storage.set({ autistmask: written });
@@ -393,8 +367,8 @@ describe("deleting without the password", () => {
 
         // The deleted wallet's secret is gone from storage entirely, not
         // merely unreferenced by the wallet list.
-        expect(JSON.stringify(storage._raw())).not.toContain("secret-two");
-        expect(JSON.stringify(storage._raw())).not.toContain("xpub-Wallet 2");
+        expect(JSON.stringify(storage.read())).not.toContain("secret-two");
+        expect(JSON.stringify(storage.read())).not.toContain("xpub-Wallet 2");
     });
 
     test("only the deleted wallet's site permissions are dropped", async () => {
@@ -462,7 +436,7 @@ describe("deleting without the password", () => {
         expect(saved.activeAddress).toBeNull();
         expect(saved.allowedSites).toEqual({});
         expect(state.currentView).toBe("welcome");
-        expect(JSON.stringify(storage._raw())).not.toContain("secret-one");
+        expect(JSON.stringify(storage.read())).not.toContain("secret-one");
     });
 });
 

tests/e2e/firefox/Dockerfile

@@ -72,6 +72,11 @@ RUN script/bootstrap
 
 COPY . .
 
-RUN make build
+# make package builds (and verifies) dist/ and then writes the release
+# artifacts, so the image carries both: run.js installs the unpacked
+# dist/firefox and reinstall.js installs the packaged .xpi, which is how the
+# artifact that would actually be handed to someone gets exercised in a real
+# Firefox rather than only being produced.
+RUN make package
 
 CMD ["node", "tests/e2e/firefox/run.js", "dist/firefox"]

tests/e2e/firefox/driver.js

@@ -103,7 +103,13 @@ class Driver {
 
     // ------------------------------------------------------------ setup
 
-    async newSession() {
+    // `profileDir` reuses an existing profile directory in place instead of
+    // letting geckodriver make a throwaway one. That is the only way to ask
+    // what survives a browser RESTART, which for a Firefox add-on that can
+    // only be installed temporarily is the question that decides whether the
+    // extension is usable at all: a temporary add-on is unloaded when Firefox
+    // exits, so every session begins by adding it again.
+    async newSession(profileDir) {
         const prefs = {
             // See EXTENSION_UUID above. The pref is a string pref whose
             // value is itself JSON.
@@ -132,26 +138,27 @@ class Driver {
             "extensions.openPopupWithoutUserGesture.enabled": false,
         };
 
+        const args = [
+            "-headless",
+            // Mandatory on Firefox 153: without it, navigating to
+            // moz-extension:// and running chrome-context script both
+            // fail with "unsupported operation".
+            //
+            // It grants the driver FULL CHROME PRIVILEGES over this
+            // browser. Acceptable only because the browser is a
+            // throwaway in a CI container; never point a session with
+            // this flag at anything you care about.
+            "-remote-allow-system-access",
+        ];
+        if (profileDir) args.push("-profile", profileDir);
+
         const value = await this.send("POST", "/session", {
             capabilities: {
                 alwaysMatch: {
                     browserName: "firefox",
                     "moz:firefoxOptions": {
                         binary: FIREFOX_BIN,
-                        args: [
-                            "-headless",
-                            // Mandatory on Firefox 153: without it,
-                            // navigating to moz-extension:// and running
-                            // chrome-context script both fail with
-                            // "unsupported operation".
-                            //
-                            // It grants the driver FULL CHROME PRIVILEGES
-                            // over this browser. Acceptable only because
-                            // the browser is a throwaway in a CI
-                            // container; never point a session with this
-                            // flag at anything you care about.
-                            "-remote-allow-system-access",
-                        ],
+                        args,
                         prefs,
                     },
                 },
@@ -162,16 +169,30 @@ class Driver {
         return value;
     }
 
-    // Installs the unpacked MV2 build straight from a directory.
-    // temporary:true bypasses signature checks, so no XPI and no signing
-    // are involved, and the add-on dies with the profile.
-    async installAddon(dir) {
+    // Installs the MV2 build, either from an unpacked directory or from an
+    // XPI file. temporary:true bypasses signature checks — which is the only
+    // way an UNSIGNED xpi installs at all, and the reason README.md says
+    // release Firefox will refuse the artifact this repo produces — and the
+    // add-on dies with the profile.
+    //
+    // Returns the add-on id Firefox assigned, which is
+    // browser_specific_settings.gecko.id from the manifest and is what
+    // uninstallAddon() takes.
+    async installAddon(pathToAddon) {
         return this.session("POST", "/moz/addon/install", {
-            path: dir,
+            path: pathToAddon,
             temporary: true,
         });
     }
 
+    // Removes an installed add-on, the way clicking Remove in about:addons
+    // does. tests/e2e/firefox/reinstall.js uses it to ask the one question
+    // that decides whether this extension can be used at all on Firefox: does
+    // the vault survive being removed and added again.
+    async uninstallAddon(id) {
+        return this.session("POST", "/moz/addon/uninstall", { id });
+    }
+
     // Classic navigation on purpose. BiDi's browsingContext.navigate
     // refuses moz-extension:// URLs outright.
     async navigate(url) {

tests/e2e/firefox/reinstall.js

@@ -0,0 +1,438 @@
+// Does the wallet survive being installed again on Firefox?
+//
+// This is the question behind
+// https://git.eeqj.de/sneak/AutistMask/issues/310, and it is the one property
+// that has to hold before real money goes into this extension. The only route
+// that works on release Firefox is a TEMPORARY add-on, which is unloaded when
+// the browser exits: daily use means adding it again from about:debugging on
+// every browser start. If extension storage did not survive that, every start
+// would present an empty wallet and the recovery phrase would be the only copy
+// of the money.
+//
+// manifest/firefox.json declares a fixed browser_specific_settings.gecko.id,
+// which is the right SHAPE for storage to survive — Firefox keys the storage
+// area by add-on id — but shape is not observation, and nothing asserted it.
+//
+// Two different things are asked here, because they have different answers and
+// conflating them would be the whole mistake:
+//
+//   RESTART      one profile, two browser runs, the add-on added temporarily
+//                in each. This is what a user does every day, and the vault
+//                has to survive it.
+//   REMOVAL      an explicit uninstall, the way about:addons "Remove" works,
+//                inside one browser run. Firefox destroys an add-on's storage
+//                when it is uninstalled, and the observed result is recorded
+//                here rather than wished away — for a wallet it means Remove
+//                is irreversible except from the recovery phrase.
+//
+// The vault is not merely compared as bytes in the restart case. It is
+// DECRYPTED with the original password through the real Show Recovery Phrase
+// screen and the phrase is compared against the one wallet creation produced,
+// because "the ciphertext is still in storage" and "the wallet still works"
+// are different claims and only the second one is worth anything.
+//
+// Run through script/test-e2e-firefox, which builds the artifact and the
+// pinned container. The one argument is what to install — an unpacked
+// directory or an .xpi. With none, the packaged XPI in release/ is used, so
+// this doubles as the check that the release artifact installs in a real
+// Firefox.
+//
+//   node tests/e2e/firefox/reinstall.js release/autistmask-firefox-0.1.0.xpi
+//
+// A separate program from run.js rather than another step in it: every step
+// there shares one browser session with one installed add-on, and this needs
+// two browsers and three installs.
+
+"use strict";
+
+const fs = require("fs");
+const os = require("os");
+const path = require("path");
+
+const { EXTENSION_ID, EXTENSION_UUID, start } = require("./driver");
+
+const REPO_ROOT = path.resolve(__dirname, "..", "..", "..");
+const PASSWORD = "e2e-harness-password";
+
+const STEP_TIMEOUT_MS = 120000;
+
+const checks = [];
+let failed = 0;
+
+function check(name, cond, detail) {
+    checks.push(name);
+    if (cond) {
+        console.log("ok " + checks.length + " - " + name);
+    } else {
+        failed += 1;
+        console.log("not ok " + checks.length + " - " + name);
+        if (detail) console.log("  " + detail);
+    }
+}
+
+// The moz-extension:// uuid Firefox currently serves this add-on from, read
+// out of the pref that holds the mapping. Privileged scope, because that pref
+// is not reachable from content.
+//
+// It has to be read after every install and never assumed. driver.js pins a
+// uuid through extensions.webextensions.uuids at each session start, but an
+// uninstall inside a running session drops that mapping and the next install
+// mints a fresh one — and navigating to the stale origin does not fail, it
+// HANGS until the session times out, which is how this was found.
+async function extensionUuid(d) {
+    const raw = await d.executeChrome(
+        `return Services.prefs.getStringPref(
+             "extensions.webextensions.uuids", "{}");`,
+    );
+    let map;
+    try {
+        map = JSON.parse(raw);
+    } catch (e) {
+        throw new Error(
+            "extensions.webextensions.uuids is not JSON (" +
+                e.message +
+                "): " +
+                raw,
+        );
+    }
+    return map[EXTENSION_ID] || null;
+}
+
+async function openPopup(d) {
+    const uuid = await extensionUuid(d);
+    if (!uuid) {
+        throw new Error(
+            "no uuid for " +
+                EXTENSION_ID +
+                " in extensions.webextensions.uuids, so the popup has no " +
+                "origin to be served from",
+        );
+    }
+    await d.navigate("moz-extension://" + uuid + "/src/popup/index.html");
+    // Whichever screen it lands on, wait for one of the two it can land on.
+    // Waiting for #view-main directly would time out rather than say what
+    // happened, and an empty storage partition is exactly the case where it
+    // lands on the other one.
+    await d.waitFor(
+        "the popup to finish restoring",
+        `const w = document.getElementById("view-welcome");
+         const m = document.getElementById("view-main");
+         if (!w || !m) return false;
+         const shown = (el) => {
+             const r = el.getBoundingClientRect();
+             return r.width > 0 && r.height > 0;
+         };
+         return shown(w) || shown(m);`,
+        [],
+        STEP_TIMEOUT_MS,
+    );
+    return uuid;
+}
+
+// The persisted record, straight out of extension storage, read from the popup
+// page — the one moz-extension:// document this program opens and therefore
+// the only place the storage API is reachable from.
+async function readVault(d) {
+    const outcome = await d.executeAsync(
+        `const done = arguments[arguments.length - 1];
+         const api = typeof browser !== "undefined" ? browser : chrome;
+         Promise.resolve(api.storage.local.get("autistmask"))
+             .then((r) => {
+                 const s = r.autistmask;
+                 if (!s) return done({ present: false });
+                 const w = (s.wallets || [])[0];
+                 if (!w) return done({ present: false });
+                 done({
+                     present: true,
+                     wallets: s.wallets.length,
+                     name: w.name,
+                     xpub: w.xpub,
+                     address: (w.addresses || []).map((a) => a.address)[0],
+                     vault: JSON.stringify(w.encryptedSecret),
+                 });
+             })
+             .catch((e) => done({ error: String((e && e.message) || e) }));`,
+    );
+    if (outcome && outcome.error) {
+        throw new Error("could not read extension storage: " + outcome.error);
+    }
+    return outcome;
+}
+
+async function createWallet(d) {
+    await d.click("#btn-welcome-add");
+    await d.waitVisible("#view-add-wallet");
+    await d.click("#btn-generate-phrase");
+    await d.waitFor(
+        "a generated recovery phrase of at least 12 words",
+        `const el = document.getElementById("wallet-mnemonic");
+         return !!el && el.value.trim().split(/\\s+/).length >= 12;`,
+    );
+    const phrase = (await d.value("#wallet-mnemonic")).trim();
+    await d.fill("#add-wallet-password", PASSWORD);
+    await d.fill("#add-wallet-password-confirm", PASSWORD);
+    await d.click("#btn-add-wallet-confirm");
+    // Argon2id under libsodium, for real.
+    await d.waitVisible("#view-main", STEP_TIMEOUT_MS);
+    return phrase;
+}
+
+// The phrase the vault decrypts to, obtained the way a user would: Settings,
+// Show Recovery Phrase, the original password.
+async function revealPhrase(d) {
+    if (!(await d.isVisible("#view-settings"))) {
+        await d.click("#btn-settings");
+    }
+    await d.waitVisible("#view-settings");
+    await d.click("#settings-wallet-list .btn-show-phrase");
+    await d.waitVisible("#view-show-phrase");
+    await d.fill("#show-phrase-password", PASSWORD);
+    await d.click("#btn-show-phrase-reveal");
+    await d.waitVisible("#show-phrase-result", STEP_TIMEOUT_MS);
+    return (await d.text("#show-phrase-value")).trim();
+}
+
+// What to install. An explicit argument wins; with none, the packaged XPI in
+// release/ is used, and there is deliberately no fallback to dist/firefox: the
+// point of running this against the artifact is that the artifact is what gets
+// installed, and quietly testing something else instead would leave the XPI
+// unexercised while the run stayed green.
+function resolveArtifact() {
+    if (process.argv[2]) return path.resolve(REPO_ROOT, process.argv[2]);
+
+    const releaseDir = path.join(REPO_ROOT, "release");
+    const xpis = fs.existsSync(releaseDir)
+        ? fs.readdirSync(releaseDir).filter((f) => f.endsWith(".xpi"))
+        : [];
+    if (xpis.length !== 1) {
+        throw new Error(
+            "expected exactly one .xpi in release/, found " +
+                xpis.length +
+                " (" +
+                xpis.join(", ") +
+                "). Run make package, or name the artifact as the argument.",
+        );
+    }
+    return path.join(releaseDir, xpis[0]);
+}
+
+async function main() {
+    let artifact;
+    try {
+        artifact = resolveArtifact();
+    } catch (e) {
+        console.error("e2e-firefox-reinstall: " + e.message);
+        process.exitCode = 1;
+        return;
+    }
+    if (!fs.existsSync(artifact)) {
+        console.error(
+            "e2e-firefox-reinstall: nothing to install at " + artifact,
+        );
+        process.exitCode = 1;
+        return;
+    }
+    console.log("# installing: " + artifact);
+
+    // One profile, reused by both browser runs below. geckodriver would
+    // otherwise make a throwaway one per session, and "survives a restart"
+    // cannot be asked of a profile that does not.
+    const profile = fs.mkdtempSync(
+        path.join(os.tmpdir(), "autistmask-reinstall-profile-"),
+    );
+
+    let phrase = null;
+    let before = null;
+    let first;
+
+    // --- run one: install, create a wallet, close the browser --------------
+    try {
+        first = await start();
+        await first.newSession(profile);
+    } catch (e) {
+        // A browser we cannot start is a failure of this program, never an
+        // absent one.
+        console.error("e2e-firefox-reinstall: cannot run: " + e.message);
+        if (first) await first.quit().catch(() => {});
+        process.exitCode = 1;
+        return;
+    }
+
+    try {
+        const firstId = await first.installAddon(artifact);
+        check(
+            "the artifact installs and reports the manifest's gecko id",
+            firstId === EXTENSION_ID,
+            "installed add-on id is " +
+                JSON.stringify(firstId) +
+                ", expected " +
+                JSON.stringify(EXTENSION_ID) +
+                ". Without a stable id Firefox has no key to hang the " +
+                "storage area on, and nothing below can hold.",
+        );
+
+        const firstUuid = await openPopup(first);
+        await first.waitVisible("#view-welcome", STEP_TIMEOUT_MS);
+        phrase = await createWallet(first);
+        before = await readVault(first);
+        check(
+            "a wallet created through the UI is in extension storage",
+            before.present && before.wallets === 1 && !!before.vault,
+            JSON.stringify(before),
+        );
+        console.log(
+            "# run 1 moz-extension uuid: " +
+                firstUuid +
+                (firstUuid === EXTENSION_UUID ? " (the pinned one)" : ""),
+        );
+    } catch (e) {
+        failed += 1;
+        console.log("# ERROR in run 1: " + (e && e.stack ? e.stack : e));
+    } finally {
+        await first.quit().catch(() => {});
+    }
+
+    // --- run two: same profile, add-on added again -------------------------
+    //
+    // This is the restart. The temporary add-on died with the previous
+    // browser; the profile, and whatever Firefox kept in it, did not.
+    let second;
+    try {
+        second = await start();
+        await second.newSession(profile);
+    } catch (e) {
+        console.error(
+            "e2e-firefox-reinstall: cannot restart the browser: " + e.message,
+        );
+        if (second) await second.quit().catch(() => {});
+        process.exitCode = 1;
+        return;
+    }
+
+    try {
+        const secondId = await second.installAddon(artifact);
+        check(
+            "the add-on installs again after a browser restart with the " +
+                "same id",
+            secondId === EXTENSION_ID,
+            "re-installed id is " + JSON.stringify(secondId),
+        );
+
+        const secondUuid = await openPopup(second);
+        // The origin the popup is served from is not the thing that carries
+        // the wallet, and the uuid is read live for exactly that reason. In
+        // this run it comes back as the pinned one, because driver.js writes
+        // extensions.webextensions.uuids into the profile at every session
+        // start; an uninstall inside a running session drops the mapping and
+        // the next install mints a fresh uuid instead. Either way the storage
+        // area is keyed on the add-on id, never on this.
+        console.log(
+            "# run 2 moz-extension uuid: " +
+                secondUuid +
+                (secondUuid === EXTENSION_UUID
+                    ? " (the pinned one, re-applied at session start)"
+                    : " (freshly minted)"),
+        );
+
+        const onWelcome = await second.isVisible("#view-welcome");
+        check(
+            "after a restart and re-add, the extension does not come up as " +
+                "a fresh install",
+            !onWelcome,
+            "the popup shows the welcome screen, which is what an empty " +
+                "storage partition looks like: the wallet is gone and only " +
+                "the recovery phrase would get it back.",
+        );
+
+        const after = await readVault(second);
+        check(
+            "the vault, xpub and first address survive the restart unchanged",
+            after.present &&
+                after.wallets === before.wallets &&
+                after.vault === before.vault &&
+                after.xpub === before.xpub &&
+                after.address === before.address,
+            "before: " +
+                JSON.stringify(before) +
+                " after: " +
+                JSON.stringify(after),
+        );
+
+        if (after.present) {
+            const revealed = await revealPhrase(second);
+            check(
+                "the vault still decrypts with the original password to the " +
+                    "original recovery phrase",
+                revealed === phrase,
+                "the recovery phrase read back after the restart is not the " +
+                    "one the wallet was created with",
+            );
+        } else {
+            check(
+                "the vault still decrypts with the original password to the " +
+                    "original recovery phrase",
+                false,
+                "there was no vault left to decrypt",
+            );
+        }
+
+        // --- an explicit removal, in the same browser run ------------------
+        //
+        // Leave the popup FIRST. Removing the add-on destroys every document
+        // it serves, and the popup is this session's only window: uninstalling
+        // while it is on screen discards the browsing context, and every
+        // subsequent WebDriver command fails with "no such window" rather than
+        // with anything about the add-on. Observed, not anticipated.
+        await second.navigate("about:blank");
+        await second.uninstallAddon(EXTENSION_ID);
+        await second.installAddon(artifact);
+        await openPopup(second);
+
+        const afterRemoval = await readVault(second);
+        console.log(
+            "# after an explicit uninstall: " + JSON.stringify(afterRemoval),
+        );
+        // Recorded as observed behaviour, not as something this repo wants.
+        // Firefox destroys an add-on's storage when it is uninstalled, and
+        // that is correct of a browser — it is stated here, and in README.md,
+        // because for a WALLET it means about:addons "Remove" is irreversible
+        // except from the recovery phrase. If a Firefox ever stops doing it
+        // this fails and the claim gets rewritten from a new observation.
+        check(
+            "an explicit uninstall DESTROYS the vault (observed Firefox " +
+                "behaviour: Remove is irreversible, unlike a restart)",
+            afterRemoval.present === false,
+            "the vault survived an explicit uninstall: " +
+                JSON.stringify(afterRemoval),
+        );
+    } catch (e) {
+        failed += 1;
+        console.log("# ERROR in run 2: " + (e && e.stack ? e.stack : e));
+    } finally {
+        await second.quit().catch(() => {});
+        fs.rmSync(profile, { recursive: true, force: true });
+    }
+
+    console.log("1.." + checks.length);
+    if (checks.length === 0) {
+        console.log("# FAILED: this program asserted nothing");
+        process.exitCode = 1;
+        return;
+    }
+    console.log(
+        "# " +
+            (checks.length - failed) +
+            "/" +
+            checks.length +
+            " checks passed",
+    );
+    if (failed > 0) {
+        console.log("# FAILED");
+        process.exitCode = 1;
+    }
+}
+
+main().catch((e) => {
+    console.error("e2e-firefox-reinstall: " + (e && e.stack ? e.stack : e));
+    process.exitCode = 1;
+});

tests/e2e/storagePartition.js

@@ -0,0 +1,303 @@
+// Where does chrome.storage.local live, and what moves it?
+//
+// The finding behind https://git.eeqj.de/sneak/AutistMask/issues/310: an
+// unpacked Chrome extension with no `key` in its manifest gets an extension id
+// derived from the ABSOLUTE PATH it was loaded from, and chrome.storage.local
+// is partitioned by that id. README.md documents Load unpacked from
+// dist/chrome/ as the install route, so moving the checkout, re-cloning it, or
+// loading a second copy from anywhere else means a different id, a different
+// storage partition, and a wallet that reads as empty — with no error, no
+// prompt and nothing in the UI to say what happened.
+//
+// So this OBSERVES the behaviour rather than restating it. Two unpacked loads
+// from two different directories, in one profile, with the shipped manifest
+// and again with `key` stripped out, and it reports what each pair actually
+// does. The assertions are on what was seen when this was written and are
+// annotated as such; if Chrome's derivation ever changes, this says so instead
+// of passing.
+//
+// Run through script/test-e2e, which builds the extension and the pinned
+// container.
+//
+//   node tests/e2e/storagePartition.js
+//
+// A separate program from run.js because every test there shares one browser
+// and one extension load, and the whole subject here is what happens across
+// two of each.
+//
+// The extension's own UI is deliberately not driven. What is under test is the
+// storage partition, so a sentinel key the extension never reads or writes is
+// written and read back directly: a wallet would prove the same thing more
+// slowly, and would confuse an empty partition with a UI that failed to
+// render.
+
+"use strict";
+
+const fs = require("fs");
+const os = require("os");
+const path = require("path");
+
+const { chromium } = require("playwright-core");
+
+const REPO_ROOT = path.resolve(__dirname, "..", "..");
+const DIST_CHROME = path.join(REPO_ROOT, "dist", "chrome");
+
+// Never touched by the extension: src/shared/state.js reads and writes the
+// single key "autistmask" and nothing else.
+const SENTINEL_KEY = "e2e-storage-partition-sentinel";
+const SENTINEL_VALUE = "written-by-the-first-load";
+
+const checks = [];
+let failed = 0;
+const scratch = [];
+
+function check(name, cond, detail) {
+    checks.push(name);
+    if (cond) {
+        console.log("ok " + checks.length + " - " + name);
+    } else {
+        failed += 1;
+        console.log("not ok " + checks.length + " - " + name);
+        if (detail) console.log("  " + detail);
+    }
+}
+
+function tmpdir(tag) {
+    const dir = fs.mkdtempSync(
+        path.join(os.tmpdir(), "autistmask-" + tag + "-"),
+    );
+    scratch.push(dir);
+    return dir;
+}
+
+// A copy of the built extension at a fresh absolute path. `withKey: false`
+// strips the manifest's `key`, which is the pre-fix state of this repo and the
+// control the whole program is built around.
+function extensionCopy(tag, withKey) {
+    const dir = path.join(tmpdir(tag), "chrome");
+    fs.cpSync(DIST_CHROME, dir, { recursive: true });
+    const manifestPath = path.join(dir, "manifest.json");
+    const manifest = JSON.parse(fs.readFileSync(manifestPath, "utf8"));
+    if (withKey) {
+        if (!manifest.key) {
+            throw new Error(
+                "dist/chrome/manifest.json has no `key`, so this program has " +
+                    "nothing to observe. That field is what pins the " +
+                    "extension id; see tests/extensionId.test.js.",
+            );
+        }
+    } else {
+        delete manifest.key;
+    }
+    fs.writeFileSync(manifestPath, JSON.stringify(manifest, null, 4));
+    return dir;
+}
+
+async function launch(profileDir, extensionDirs) {
+    const ctx = await chromium.launchPersistentContext(profileDir, {
+        // See the note in harness.js: the default headless shell silently
+        // refuses to load extensions.
+        channel: "chromium",
+        headless: true,
+        args: [
+            "--disable-extensions-except=" + extensionDirs.join(","),
+            "--load-extension=" + extensionDirs.join(","),
+            "--no-sandbox",
+            // Nothing here should reach the network; this makes sure it
+            // cannot.
+            "--host-resolver-rules=MAP * ~NOTFOUND",
+        ],
+    });
+    return ctx;
+}
+
+// Every extension id Chrome ended up with in this context, from the service
+// worker urls. MV3 registers one worker per loaded extension.
+async function extensionIds(ctx, expected) {
+    const deadline = Date.now() + 30000;
+    for (;;) {
+        const ids = [
+            ...new Set(ctx.serviceWorkers().map((w) => new URL(w.url()).host)),
+        ].sort();
+        if (ids.length >= expected) return ids;
+        if (Date.now() > deadline) return ids;
+        await new Promise((r) => setTimeout(r, 200));
+    }
+}
+
+// Open one extension's popup and run `fn` in it. The popup page is used rather
+// than the service worker because Chrome stops an idle MV3 worker, and a
+// handle to a stopped worker cannot be evaluated in.
+async function inExtension(ctx, id, fn, arg) {
+    const page = await ctx.newPage();
+    try {
+        await page.goto("chrome-extension://" + id + "/src/popup/index.html");
+        return await page.evaluate(fn, arg);
+    } finally {
+        await page.close();
+    }
+}
+
+const writeSentinel = ([key, value]) =>
+    new Promise((resolve) => {
+        chrome.storage.local.set({ [key]: value }, () => resolve(true));
+    });
+
+const readSentinel = (key) =>
+    new Promise((resolve) => {
+        chrome.storage.local.get(key, (r) => resolve(r[key] ?? null));
+    });
+
+// Load `firstDir` in a fresh profile, write the sentinel, close; load
+// `secondDir` in the SAME profile, read it back. Returns both ids and what the
+// second load saw.
+async function acrossTwoPaths(tag, firstDir, secondDir) {
+    const profile = tmpdir(tag + "-profile");
+
+    const first = await launch(profile, [firstDir]);
+    let firstId;
+    try {
+        [firstId] = await extensionIds(first, 1);
+        if (!firstId) throw new Error("no extension loaded from " + firstDir);
+        await inExtension(first, firstId, writeSentinel, [
+            SENTINEL_KEY,
+            SENTINEL_VALUE,
+        ]);
+    } finally {
+        await first.close();
+    }
+
+    const second = await launch(profile, [secondDir]);
+    let secondId;
+    let seen;
+    try {
+        [secondId] = await extensionIds(second, 1);
+        if (!secondId) throw new Error("no extension loaded from " + secondDir);
+        seen = await inExtension(second, secondId, readSentinel, SENTINEL_KEY);
+    } finally {
+        await second.close();
+    }
+
+    return { firstId, secondId, seen };
+}
+
+async function main() {
+    if (!fs.existsSync(path.join(DIST_CHROME, "manifest.json"))) {
+        console.error(
+            "storagePartition: no unpacked build at " +
+                DIST_CHROME +
+                " — run make build first",
+        );
+        process.exitCode = 1;
+        return;
+    }
+
+    try {
+        // --- the shipped manifest, which carries `key` ----------------------
+        const keyedA = extensionCopy("keyed-a", true);
+        const keyedB = extensionCopy("keyed-b", true);
+        const keyed = await acrossTwoPaths("keyed", keyedA, keyedB);
+        console.log("# with `key`:    " + keyedA + " -> " + keyed.firstId);
+        console.log("# with `key`:    " + keyedB + " -> " + keyed.secondId);
+        console.log("# with `key`:    sentinel read back: " + keyed.seen);
+
+        check(
+            "with `key`, two different paths produce the SAME extension id",
+            keyed.firstId === keyed.secondId,
+            keyed.firstId + " != " + keyed.secondId,
+        );
+        check(
+            "with `key`, the second path reads the first path's storage",
+            keyed.seen === SENTINEL_VALUE,
+            "the second load read " +
+                JSON.stringify(keyed.seen) +
+                " instead of the value the first load wrote. The storage " +
+                "partition did not follow the extension across the move, " +
+                "which is the wallet silently reading as empty.",
+        );
+
+        // --- the same build with `key` removed: the control -----------------
+        const barePath = extensionCopy("bare-a", false);
+        const bareB = extensionCopy("bare-b", false);
+        const bare = await acrossTwoPaths("bare", barePath, bareB);
+        console.log("# without `key`: " + barePath + " -> " + bare.firstId);
+        console.log("# without `key`: " + bareB + " -> " + bare.secondId);
+        console.log("# without `key`: sentinel read back: " + bare.seen);
+
+        // Observed, not assumed. If Chrome ever stops deriving the id from
+        // the load path these two fail, and the right response is to record
+        // what it does now — not to delete them.
+        check(
+            "without `key`, two different paths produce DIFFERENT ids " +
+                "(observed Chrome behaviour, the defect this fixes)",
+            bare.firstId !== bare.secondId,
+            "both loads got " +
+                bare.firstId +
+                ", so the id no longer follows the load path on this Chrome",
+        );
+        check(
+            "without `key`, the second path sees an EMPTY partition " +
+                "(observed Chrome behaviour, the defect this fixes)",
+            bare.seen === null,
+            "the second load read " +
+                JSON.stringify(bare.seen) +
+                " from a different id's partition",
+        );
+
+        // --- both copies loaded at once, in one profile ---------------------
+        // The literal shape of the question, kept because "two unpacked loads
+        // in one profile" is what a user does when they forget to remove the
+        // old one. With `key`, both copies claim the same id.
+        const profile = tmpdir("simultaneous-profile");
+        const ctx = await launch(profile, [keyedA, keyedB]);
+        let ids = [];
+        try {
+            ids = await extensionIds(ctx, 2);
+        } finally {
+            await ctx.close();
+        }
+        console.log(
+            "# both keyed copies loaded at once: " +
+                ids.length +
+                " extension id(s): " +
+                ids.join(", "),
+        );
+        check(
+            "loading both keyed copies at once yields one id, not two " +
+                "(observed: Chrome does not load a second copy of an id it " +
+                "already has)",
+            ids.length === 1 && ids[0] === keyed.firstId,
+            "saw " + JSON.stringify(ids) + ", expected exactly one id",
+        );
+    } catch (e) {
+        failed += 1;
+        console.log("# ERROR: " + (e && e.stack ? e.stack : e));
+    } finally {
+        for (const dir of scratch) {
+            fs.rmSync(dir, { recursive: true, force: true });
+        }
+    }
+
+    console.log("1.." + checks.length);
+    if (checks.length === 0) {
+        console.log("# FAILED: this program asserted nothing");
+        process.exitCode = 1;
+        return;
+    }
+    console.log(
+        "# " +
+            (checks.length - failed) +
+            "/" +
+            checks.length +
+            " checks passed",
+    );
+    if (failed > 0) {
+        console.log("# FAILED");
+        process.exitCode = 1;
+    }
+}
+
+main().catch((e) => {
+    console.error("storagePartition: " + (e && e.stack ? e.stack : e));
+    process.exitCode = 1;
+});

tests/extensionId.test.js

@@ -0,0 +1,119 @@
+// The extension identity on both browsers, pinned.
+//
+// This is the anti-regression check for
+// https://git.eeqj.de/sneak/AutistMask/issues/310. An unpacked Chrome
+// extension with no `key` in its manifest gets an id derived from the
+// ABSOLUTE PATH it was loaded from, and chrome.storage.local is partitioned by
+// that id. Move the checkout, re-clone it, or load it from a second directory,
+// and the wallet is silently gone: the extension comes up on a fresh, empty
+// storage partition with no error anywhere. `key` pins the id to the public
+// key instead of to the path, which is what makes the storage survive.
+//
+// So the id is asserted as a literal. A test that merely recomputed the id
+// from whatever `key` happened to be in the manifest would pass after someone
+// replaced the key — and replacing the key is exactly the change that orphans
+// every existing wallet. The value below is the promise; changing it is a
+// migration, not an edit.
+//
+// Firefox needs no key: browser_specific_settings.gecko.id declares the id
+// directly, and it is pinned here for the same reason. The Firefox e2e suite
+// depends on it too (tests/e2e/firefox/driver.js maps it to a fixed uuid), and
+// tests/e2e/firefox/reinstall.js is the empirical half — it removes the add-on
+// and installs it again and reads the vault back out.
+
+const crypto = require("crypto");
+const fs = require("fs");
+const path = require("path");
+
+const MANIFEST_DIR = path.join(__dirname, "..", "manifest");
+
+// The public half of an RSA keypair, DER-encoded SubjectPublicKeyInfo, base64.
+// The PRIVATE half is not in this repo and is not needed to build, load or
+// test anything here: it is only ever used to sign a CRX, which this repo does
+// not do.
+const CHROME_KEY =
+    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzy/G9gT4Z3Ci0HCmthUPEiCjENg+" +
+    "5meZpjdogyT7SiMfxENtHdrpDL6wGhAg1Dk0f1C67Ft8OYpMrMH3kiP2Wnt0UpHo45PY0YUU" +
+    "YzdJgbsp8u0kaykd5FFiY6FycIIFaTniMuh7wRKuNNdJWly+H3aG7qZ6nGu5PIMdb1GXUk35" +
+    "hY+yl7dz5dqFFYUCyxvWCT9XGBSYiI+XRBB/rVZjMWfWpaTmRPdOZ4+GO/Lx0OdMxKlPA/kL" +
+    "WoPot5vMlLn2FDPu6sASphiu7dKZnrINW+h/27jlHMJQS0jncB1EgqOHW0vbXrZnTveFX6UW" +
+    "+Qp86FfSkikhKtQgTW2A4mtWawIDAQAB";
+
+// chrome.storage.local for this extension lives under this id, and nowhere
+// else.
+const CHROME_EXTENSION_ID = "gipbhkogfopeahplcjhipkgpcimdpkip";
+
+const FIREFOX_EXTENSION_ID = "autistmask@sneak.berlin";
+
+// Chrome's id derivation: sha256 of the DER public key, first 16 bytes, each
+// hex digit mapped 0-f onto a-p. Written out here rather than taken on trust,
+// because the whole claim of this file is that the committed key produces that
+// id.
+function chromeExtensionId(keyBase64) {
+    const der = Buffer.from(keyBase64, "base64");
+    const digest = crypto.createHash("sha256").update(der).digest("hex");
+    return [...digest.slice(0, 32)]
+        .map((c) => String.fromCharCode(97 + parseInt(c, 16)))
+        .join("");
+}
+
+function readManifest(name) {
+    return JSON.parse(
+        fs.readFileSync(path.join(MANIFEST_DIR, name + ".json"), "utf8"),
+    );
+}
+
+describe("chrome extension identity", () => {
+    test("the manifest carries the pinned key", () => {
+        expect(readManifest("chrome").key).toBe(CHROME_KEY);
+    });
+
+    test("the key is a well-formed RSA public key", () => {
+        const der = Buffer.from(CHROME_KEY, "base64");
+        // Round-trips: a truncated or re-wrapped base64 blob would still
+        // decode to bytes, and Chrome would then derive an id from garbage.
+        expect(der.toString("base64")).toBe(CHROME_KEY);
+        const key = crypto.createPublicKey({
+            key: der,
+            format: "der",
+            type: "spki",
+        });
+        expect(key.asymmetricKeyType).toBe("rsa");
+        expect(key.asymmetricKeyDetails.modulusLength).toBe(2048);
+    });
+
+    test("the key derives the pinned extension id", () => {
+        expect(chromeExtensionId(CHROME_KEY)).toBe(CHROME_EXTENSION_ID);
+        expect(CHROME_EXTENSION_ID).toMatch(/^[a-p]{32}$/);
+    });
+
+    // The private half is a credential. It has never been in this repo and no
+    // target generates one into the working tree; this fails loudly if that
+    // ever changes, because a committed .pem is a key anyone can sign a CRX
+    // with under this extension's id.
+    test("no private key is committed anywhere in the tree", () => {
+        const tracked = require("child_process")
+            .execSync("git ls-files", {
+                cwd: path.join(__dirname, ".."),
+                encoding: "utf8",
+            })
+            .split("\n")
+            .filter(Boolean);
+        expect(tracked.filter((f) => /\.(pem|key|p12|pfx)$/i.test(f))).toEqual(
+            [],
+        );
+    });
+});
+
+describe("firefox extension identity", () => {
+    test("the manifest declares the pinned gecko id", () => {
+        const gecko = readManifest("firefox").browser_specific_settings.gecko;
+        expect(gecko.id).toBe(FIREFOX_EXTENSION_ID);
+    });
+
+    // Firefox derives nothing from the path, so no key field belongs here; one
+    // would be ignored and would only suggest the id came from somewhere else.
+    test("the firefox manifest carries no chrome key field", () => {
+        expect(readManifest("firefox").key).toBeUndefined();
+    });
+});

tests/networkEndpoints.test.js

@@ -10,6 +10,7 @@
 // happened.
 
 const { networkById } = require("../src/shared/networks");
+const { makeStorageStub } = require("./support/storageStub");
 
 const ADDRESS = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
 
@@ -34,25 +35,19 @@ function walletFixture() {
 // saveState() wrote — so a case can reload a fresh module from the bytes an
 // earlier one persisted, which is what an extension restart does. `state` is
 // a module-level singleton, so the registry has to be reset per load.
+// The stub clones in both directions, as the real chrome.storage.local does.
+// It used to alias, and written() then handed the NEXT module load the live
+// in-memory object of the previous one as its "persisted bytes" — an extension
+// restart that never crossed a serialization boundary. See
+// tests/support/storageStub.js.
 function loadModuleWith(persisted) {
     jest.resetModules();
-    let written = null;
-    global.chrome = {
-        storage: {
-            local: {
-                get: jest.fn(async () =>
-                    persisted ? { autistmask: persisted } : {},
-                ),
-                set: jest.fn(async (items) => {
-                    written = items.autistmask;
-                }),
-            },
-        },
-    };
+    const storage = makeStorageStub(persisted ? { autistmask: persisted } : {});
+    global.chrome = { storage };
     return {
         mod: require("../src/shared/state"),
         chainSwitch: require("../src/shared/chainSwitch"),
-        written: () => written,
+        written: () => storage.read("autistmask"),
     };
 }
 

tests/packaging.test.js

@@ -0,0 +1,190 @@
+// The release archives: the zip container, and the self-containment rule.
+//
+// script/package produces one archive per browser and script/lib/package.js
+// decides what goes in it. The trap that rule exists for is real and specific:
+// build.js writes the compiled stylesheet to dist/styles.css at the dist/
+// ROOT, outside both browser directories, and copies it into each of them as
+// src/popup/styles.css. A `zip -r dist/chrome` is correct only because of that
+// copy, and would silently start shipping a popup with no stylesheet the
+// moment a reference pointed up and out of the directory.
+//
+// So the packager resolves every reference in the manifest and in every HTML
+// document, and fails on any that leaves the extension root. These are the
+// cases for that, plus the archive format itself — new code, and the thing the
+// artifact is made of.
+
+const {
+    checkSelfContained,
+    htmlReferences,
+    manifestReferences,
+} = require("../script/lib/package");
+const { readZip, writeZip } = require("../script/lib/zip");
+
+function archiveOf(files) {
+    return {
+        members: Object.keys(files).sort(),
+        read: (name) => Buffer.from(files[name] ?? "", "utf8"),
+    };
+}
+
+const MINIMAL_MANIFEST = {
+    manifest_version: 3,
+    name: "AutistMask",
+    version: "0.1.0",
+    action: { default_popup: "src/popup/index.html" },
+    background: { service_worker: "src/background/index.js" },
+};
+
+describe("archive self-containment", () => {
+    test("a complete tree passes", () => {
+        const { members, read } = archiveOf({
+            "manifest.json": JSON.stringify(MINIMAL_MANIFEST),
+            "src/popup/index.html":
+                '<link rel="stylesheet" href="styles.css" />' +
+                '<script src="index.js"></script>',
+            "src/popup/styles.css": "body{}",
+            "src/popup/index.js": "//",
+            "src/background/index.js": "//",
+        });
+        expect(() => checkSelfContained("chrome", members, read)).not.toThrow();
+    });
+
+    test("a manifest naming a file that is not in the archive fails", () => {
+        const { members, read } = archiveOf({
+            "manifest.json": JSON.stringify(MINIMAL_MANIFEST),
+            "src/popup/index.html": "<html></html>",
+            "src/popup/index.js": "//",
+        });
+        expect(() => checkSelfContained("chrome", members, read)).toThrow(
+            /would not be self-contained.*src\/background\/index\.js/s,
+        );
+    });
+
+    // The dist/styles.css case, exactly: a popup that reached up out of its
+    // own browser directory for the stylesheet the build leaves at the dist/
+    // root. Nothing would be missing from disk, and the zip would still be
+    // built — the archive would just have no stylesheet in it.
+    test("an HTML reference that escapes the extension root fails", () => {
+        const { members, read } = archiveOf({
+            "manifest.json": JSON.stringify(MINIMAL_MANIFEST),
+            "src/popup/index.html":
+                '<link rel="stylesheet" href="../../../styles.css" />',
+            "src/popup/index.js": "//",
+            "src/background/index.js": "//",
+        });
+        expect(() => checkSelfContained("chrome", members, read)).toThrow(
+            /resolves outside the extension root/,
+        );
+    });
+
+    test("a manifest reference that escapes the extension root fails", () => {
+        const { members, read } = archiveOf({
+            "manifest.json": JSON.stringify({
+                ...MINIMAL_MANIFEST,
+                background: { service_worker: "../shared/index.js" },
+            }),
+            "src/popup/index.html": "<html></html>",
+        });
+        expect(() => checkSelfContained("chrome", members, read)).toThrow(
+            /points outside the extension root/,
+        );
+    });
+
+    test("an archive with no manifest.json at its root fails", () => {
+        const { members, read } = archiveOf({ "src/popup/index.js": "//" });
+        expect(() => checkSelfContained("chrome", members, read)).toThrow(
+            /no manifest\.json at its root/,
+        );
+    });
+
+    test("manifest strings that are not paths are not treated as files", () => {
+        const found = manifestReferences({
+            name: "AutistMask",
+            version: "0.1.0",
+            permissions: ["storage", "<all_urls>"],
+            content_security_policy: {
+                extension_pages: "default-src 'self'; script-src 'self'",
+            },
+            key: "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzy",
+        });
+        expect([...found]).toEqual([]);
+    });
+
+    test("absolute, data: and anchor HTML references are not files", () => {
+        const refs = htmlReferences(
+            "src/popup/index.html",
+            '<a href="https://example.com/x.js">a</a>' +
+                '<img src="data:image/png;base64,AAAA" />' +
+                '<a href="#view-main">b</a>' +
+                '<script src="index.js"></script>',
+        );
+        expect([...refs]).toEqual(["src/popup/index.js"]);
+    });
+});
+
+describe("the zip container", () => {
+    const files = [
+        { name: "manifest.json", data: Buffer.from('{"a":1}') },
+        // Long enough that deflate wins, so both paths through compress() are
+        // exercised by one archive.
+        { name: "src/popup/index.js", data: Buffer.from("x".repeat(5000)) },
+        { name: "empty.txt", data: Buffer.alloc(0) },
+    ];
+
+    test("round-trips every member byte for byte", () => {
+        const entries = readZip(writeZip(files));
+        expect(entries.map((e) => e.name)).toEqual([
+            "empty.txt",
+            "manifest.json",
+            "src/popup/index.js",
+        ]);
+        for (const original of files) {
+            const found = entries.find((e) => e.name === original.name);
+            expect(found.data.equals(original.data)).toBe(true);
+        }
+    });
+
+    // The sha256 in release/SHA256SUMS has to be a property of the input. Two
+    // builds of one commit that produce different archives cannot be compared
+    // to each other, which is most of what publishing a digest is for.
+    test("is byte-identical across runs and independent of input order", () => {
+        const a = writeZip(files);
+        const b = writeZip([...files].reverse());
+        expect(a.equals(b)).toBe(true);
+    });
+
+    // Reading an archive back is how script/lib/package.js establishes that
+    // the artifact holds what dist/ holds, so a member whose bytes changed
+    // after it was written has to fail rather than be handed back.
+    test("a corrupted member fails its CRC on read", () => {
+        // One member, incompressible at this size, so it is stored verbatim
+        // and its bytes begin at a known offset: local header (30) + name.
+        const name = "a.js";
+        const archive = writeZip([{ name, data: Buffer.from("hello") }]);
+        expect(readZip(archive)[0].data.toString()).toBe("hello");
+        archive[30 + name.length] ^= 0xff;
+        expect(() => readZip(archive)).toThrow(/fails its recorded CRC32/);
+    });
+
+    test.each([["/abs.js"], ["../up.js"], ["a/../b.js"], ["a\\b.js"], [""]])(
+        "refuses the member name %p",
+        (name) => {
+            expect(() => writeZip([{ name, data: Buffer.from("x") }])).toThrow(
+                /member name/,
+            );
+        },
+    );
+
+    test("refuses an archive with no members", () => {
+        expect(() => writeZip([])).toThrow(/no members/);
+    });
+
+    test("refuses duplicate members", () => {
+        expect(() =>
+            writeZip([
+                { name: "a.js", data: Buffer.from("1") },
+                { name: "a.js", data: Buffer.from("2") },
+            ]),
+        ).toThrow(/duplicate member/);
+    });
+});

tests/settingsUtcTimestamps.test.js

@@ -9,6 +9,8 @@
 const fs = require("fs");
 const path = require("path");
 
+const { makeStorageStub } = require("./support/storageStub");
+
 const POPUP_HTML = fs.readFileSync(
     path.join(__dirname, "..", "src", "popup", "index.html"),
     "utf8",
@@ -51,19 +53,17 @@ describe("the UTC Timestamps checkbox placement", () => {
 });
 
 describe("the UTC Timestamps setting round-trips through storage", () => {
-    let store;
+    let storage;
 
+    // The stub clones in both directions, as the real chrome.storage.local
+    // does. It used to alias, which is fatal to a round-trip test in
+    // particular: the object the module holds and the object "storage" holds
+    // are then the same object, so the setting appears to have been persisted
+    // and read back on a build where neither happened. See
+    // tests/support/storageStub.js.
     function loadStateModule() {
-        store = {};
-        global.chrome = {
-            storage: {
-                local: {
-                    get: async (key) =>
-                        key in store ? { [key]: store[key] } : {},
-                    set: async (obj) => Object.assign(store, obj),
-                },
-            },
-        };
+        storage = makeStorageStub();
+        global.chrome = { storage };
         jest.resetModules();
         return require("../src/shared/state");
     }
@@ -86,12 +86,18 @@ describe("the UTC Timestamps setting round-trips through storage", () => {
         // What the change handler in views/settings.js does.
         first.state.utcTimestamps = true;
         await first.saveState();
-        expect(store.autistmask.utcTimestamps).toBe(true);
+        expect(storage.read("autistmask").utcTimestamps).toBe(true);
 
-        // A fresh popup load sees it.
+        // A fresh popup load sees it — and, before that load, refuses to
+        // answer at all rather than reporting the default. That refusal is
+        // what makes the assertion below evidence of a read from storage
+        // instead of a value that was already sitting in memory
+        // (https://git.eeqj.de/sneak/AutistMask/issues/324).
         jest.resetModules();
         const second = require("../src/shared/state");
-        expect(second.state.utcTimestamps).toBe(false);
+        expect(() => second.state.utcTimestamps).toThrow(
+            second.StateNotLoadedError,
+        );
         await second.loadState();
         expect(second.state.utcTimestamps).toBe(true);
     });

tests/state.test.js

@@ -4,23 +4,24 @@ function oneWallet() {
     return [{ name: "Wallet 1", type: "hd", addresses: [ADDRESS] }];
 }
 
+const { makeStorageStub } = require("./support/storageStub");
+
 // state.js resolves the storage API at require time, so the stub has to exist
 // before the module is loaded, and the module registry has to be reset between
 // cases because `state` is a module-level singleton.
+//
+// The stub clones in both directions, as the real chrome.storage.local does —
+// see tests/support/storageStub.js for why an aliasing one made this file
+// assert less than it appears to.
 function loadModuleWith(persisted) {
     jest.resetModules();
-    const set = jest.fn(async () => {});
-    global.chrome = {
-        storage: {
-            local: {
-                get: jest.fn(async () =>
-                    persisted ? { autistmask: persisted } : {},
-                ),
-                set,
-            },
-        },
+    const storage = makeStorageStub(persisted ? { autistmask: persisted } : {});
+    global.chrome = { storage };
+    return {
+        mod: require("../src/shared/state"),
+        set: storage.set,
+        stored: () => storage.read("autistmask"),
     };
-    return { mod: require("../src/shared/state"), set };
 }
 
 afterEach(() => {

tests/stateMerge.test.js

@@ -10,32 +10,12 @@
 //
 // Both cases below drive the real state.js module through two independent
 // module registries sharing one storage backend, the way two real extension
-// pages share one chrome.storage.local. The storage stub structured-clones
-// on both get and set — a stub that hands back the object it was given
-// aliases the caller's own mutation and would make this entire defect class
-// invisible (see https://git.eeqj.de/sneak/AutistMask/issues/324).
+// pages share one chrome.storage.local. The shared stub structured-clones on
+// both get and set — a stub that hands back the object it was given aliases
+// the caller's own mutation and would make this entire defect class invisible
+// (see https://git.eeqj.de/sneak/AutistMask/issues/324).
 
-function makeStorage() {
-    let store = {};
-    return {
-        get: async (keys) => {
-            const wanted =
-                keys === undefined || keys === null
-                    ? Object.keys(store)
-                    : [].concat(keys);
-            const out = {};
-            for (const key of wanted) {
-                if (key in store) out[key] = structuredClone(store[key]);
-            }
-            return out;
-        },
-        set: async (items) => {
-            for (const [key, value] of Object.entries(items)) {
-                store[key] = structuredClone(value);
-            }
-        },
-    };
-}
+const { makeStorageStub } = require("./support/storageStub");
 
 // One extension page: a fresh module registry over the shared storage.
 // state.js resolves the storage API at require time, so the stub has to be
@@ -43,7 +23,7 @@ function makeStorage() {
 // singleton, so each page needs its own registry to hold its own copy.
 function loadPage(storage) {
     jest.resetModules();
-    globalThis.chrome = { storage: { local: storage } };
+    globalThis.chrome = { storage: { local: storage.local } };
     return {
         state: require("../src/shared/state"),
         helpers: require("../src/popup/views/helpers"),
@@ -118,7 +98,7 @@ describe("a save from a page that never saw a wallet another page added", () =>
     // a save from a second page loaded before that wallet existed. Both
     // wallets must survive.
     test("both wallets are in storage afterwards", async () => {
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         await storage.set({ autistmask: { wallets: [W1] } });
 
         // Loaded while storage held only Wallet 1, and never reloads —
@@ -171,7 +151,7 @@ describe("the approval-window reproduction", () => {
     test("the wallet added in the popup survives confirming the approval", async () => {
         globalThis.document = makeDocument();
 
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         await storage.set({ autistmask: { wallets: [W1] } });
 
         // The background opens the approval window on the approve-tx
@@ -223,7 +203,7 @@ describe("the approval-window reproduction", () => {
 // membership" collided as the same field.
 describe("background refresh racing a wallet added on another page", () => {
     test("the wallet added elsewhere survives background's stale balance save", async () => {
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         await storage.set({ autistmask: { wallets: [W1] } });
 
         // "background": loads first, and its save is the one that lands
@@ -263,7 +243,7 @@ describe("background refresh racing a wallet added on another page", () => {
 
 describe("background refresh racing a wallet deleted on another page", () => {
     test("the wallet deleted elsewhere stays deleted after background's stale balance save", async () => {
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         await storage.set({ autistmask: { wallets: [W1, W2] } });
 
         const background = loadPage(storage);
@@ -324,7 +304,7 @@ function revokeSite(pageState, hostname) {
 
 describe("a dApp approval racing a stale Settings page's later save", () => {
     test("the fresh approval survives Settings revoking an unrelated site", async () => {
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         await storage.set({
             autistmask: {
                 wallets: [W1],
@@ -362,7 +342,7 @@ describe("a dApp approval racing a stale Settings page's later save", () => {
 
 describe("a revoked site permission against a stale page's later save", () => {
     test("the revocation holds even when the stale page approves something else", async () => {
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         await storage.set({
             autistmask: {
                 wallets: [W1],
@@ -413,7 +393,7 @@ function legacyWallet(name, secret) {
 
 describe("two wallets independently created with a colliding identity", () => {
     test("both survive, encryptedSecret included, instead of one silently replacing the other", async () => {
-        const storage = makeStorage();
+        const storage = makeStorageStub();
         await storage.set({ autistmask: { wallets: [W1] } });
 
         // Both pages load before either has created their malformed wallet,

tests/support/storageStub.js

@@ -0,0 +1,73 @@
+// A chrome.storage.local stub that behaves like the real one.
+//
+// The real extension storage API is a serialization boundary: `set` writes a
+// structured clone of what it is given, and `get` hands back a structured
+// clone of what is stored. Nothing an extension page holds is ever the object
+// storage holds.
+//
+// A stub that skips the clone aliases them together, and that hides an entire
+// class of defect rather than merely being imprecise. loadState() assigns
+// nested references straight out of the get result, so over an aliasing stub a
+// test can assert "the endpoint was persisted" and pass on a build that never
+// called saveState() at all: the in-memory mutation IS the stored record.
+// Measured, not theorised — with an aliasing `get` restored over the handler
+// fixed in https://git.eeqj.de/sneak/AutistMask/pulls/319, the whole suite
+// passed 794/794 (https://git.eeqj.de/sneak/AutistMask/issues/324).
+//
+// So every test that drives real persistence uses this, and nothing rebuilds
+// a storage stub by hand.
+
+// `initial` is the starting contents, keyed as storage is: { autistmask: {...} }.
+// `onOp` runs before each operation, for a test that needs to advance a clock
+// or count round trips.
+function makeStorageStub(initial, onOp) {
+    const store = initial ? structuredClone(initial) : {};
+    const tick = onOp || (() => {});
+
+    const get = jest.fn(async (key) => {
+        tick();
+        if (key === undefined || key === null) return structuredClone(store);
+        const keys = Array.isArray(key) ? key : [key];
+        const out = {};
+        for (const k of keys) {
+            if (Object.prototype.hasOwnProperty.call(store, k)) {
+                out[k] = structuredClone(store[k]);
+            }
+        }
+        return out;
+    });
+
+    const set = jest.fn(async (items) => {
+        tick();
+        for (const k of Object.keys(items)) {
+            store[k] = structuredClone(items[k]);
+        }
+    });
+
+    const remove = jest.fn(async (key) => {
+        tick();
+        for (const k of Array.isArray(key) ? key : [key]) delete store[k];
+    });
+
+    return {
+        // Drop this straight in as chrome.storage.
+        local: { get, set, remove },
+        get,
+        set,
+        remove,
+        // What is stored, cloned on the way out: a test can neither observe a
+        // later write through an object it read nor reach into the store by
+        // mutating one.
+        read: (key) =>
+            key === undefined
+                ? structuredClone(store)
+                : structuredClone(store[key]),
+        // Seed or replace a record without going through the module under
+        // test — for standing in as "another page wrote this".
+        write: (key, value) => {
+            store[key] = structuredClone(value);
+        },
+    };
+}
+
+module.exports = { makeStorageStub };

tests/symbolSpoof.test.js

@@ -682,6 +682,7 @@ describe("surface 3: the balance list", () => {
             "https://rpc.example.invalid",
             BLOCKSCOUT,
             [],
+            "mainnet",
         );
         expect(addr.balance).toBe("1.2345");
         expect(addr.tokenBalances).toEqual([]);

tests/transactions.test.js

@@ -30,8 +30,11 @@ global.fetch = jest.fn(() => {
 });
 
 // state.js reads chrome.storage.local at module load; stub it so the
-// default settings can be asserted against what the README promises.
-global.chrome = { storage: { local: {} } };
+// default settings can be asserted against what the README promises. Empty
+// storage, so a load produces exactly the defaults.
+const { makeStorageStub } = require("./support/storageStub");
+
+global.chrome = { storage: makeStorageStub() };
 
 const {
     fetchRecentTransactions,
@@ -745,6 +748,16 @@ describe("dust threshold filtering", () => {
 });
 
 describe("filter defaults promised by the README and Settings", () => {
+    // The defaults are what a load of empty storage produces, so the load is
+    // part of the assertion rather than an incantation before it: reading the
+    // singleton before any load now throws (StateNotLoadedError), because a
+    // context served DEFAULT_STATE without asking for it is the whole subject
+    // of https://git.eeqj.de/sneak/AutistMask/issues/324. The stub at the top
+    // of this file has storage empty.
+    beforeAll(async () => {
+        await require("../src/shared/state").loadState();
+    });
+
     test("all four toggles default to on and the threshold to 100,000 gwei", () => {
         expect(state.hideSpoofedSymbols).toBe(true);
         expect(state.hideLowHolderTokens).toBe(true);

tests/txStatus.test.js

@@ -96,18 +96,14 @@ global.document = {
 
 global.window = { location: { search: "" } };
 
-const stored = {};
-global.chrome = {
-    storage: {
-        local: {
-            set: (obj) => {
-                Object.assign(stored, obj);
-                return Promise.resolve();
-            },
-            get: () => Promise.resolve(stored),
-        },
-    },
-};
+// Clones in both directions, as the real chrome.storage.local does; the stub
+// here used to hand back the live stored object, so an in-memory mutation
+// looked like a write that had reached storage. See
+// tests/support/storageStub.js.
+const { makeStorageStub } = require("./support/storageStub");
+
+const storage = makeStorageStub();
+global.chrome = { storage };
 
 const txStatus = require("../src/popup/views/txStatus");
 const { state } = require("../src/shared/state");

tests/uniswapUnknownDecimals.test.js

@@ -0,0 +1,176 @@
+// The scale the swap lines of the dApp approval screen are displayed with.
+//
+// Issue #340: `tokenInfo()` in `src/shared/uniswap.js` returned `decimals: 18`
+// for any token absent from the bundled list — the same guess
+// https://git.eeqj.de/sneak/AutistMask/issues/306 removed from the ERC-20
+// amount line, still live on the swap path. A 1,000-token swap of a 6-decimal
+// token then rendered as `0.000000001` on the one screen whose job is to state
+// what is being authorized, and every newly listed token reaches it.
+//
+// What is asserted here is the rule #306 established: resolve the real scale
+// wherever the wallet already has it, and where nothing has it refuse to
+// format — base units with the scale stated, never a quantity.
+
+globalThis.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { AbiCoder, Interface } = require("ethers");
+const { state } = require("../src/shared/state");
+const { unknownDecimalsAmount } = require("../src/shared/approvalAmount");
+const { decodeCalldata } = require("../src/popup/views/approval");
+
+const ROUTER = "0x66a9893cc07d91d95644aedd05d03f95e1dba8af";
+const RECIPIENT = "0xC0FfEE0000000000000000000000000000c0fFEe";
+// Outside the bundled list, as every newly listed token is.
+const NOVEL = "0xE2E0000000000000000000000000000000000E2e";
+// Also outside it, standing in for the swap's output side.
+const NOVEL_OUT = "0xd0d0000000000000000000000000000000000d0d";
+// In the bundled list, at 18 decimals.
+const WETH = "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2";
+
+// 1,000.00 of a 6-decimal token — the amount from the issue, which the 18
+// guess rendered as 0.000000001.
+const THOUSAND_AT_SIX = 1000000000n;
+// 0.5 WETH out, so the Min. received line has a real number of its own.
+const HALF_WETH = 500000000000000000n;
+
+const coder = AbiCoder.defaultAbiCoder();
+const routerIface = new Interface([
+    "function execute(bytes commands, bytes[] inputs, uint256 deadline)",
+]);
+
+// A V2_SWAP_EXACT_IN (command 0x08) execute() call: `amountIn` of `tokenIn`
+// for at least `amountOutMin` of `tokenOut`.
+function swapData(tokenIn, amountIn, tokenOut, amountOutMin) {
+    const input = coder.encode(
+        ["address", "uint256", "uint256", "address[]", "bool"],
+        [RECIPIENT, amountIn, amountOutMin, [tokenIn, tokenOut], true],
+    );
+    return routerIface.encodeFunctionData("execute", [
+        "0x08",
+        [input],
+        9999999999n,
+    ]);
+}
+
+// A wallet holding `token` with the decimals the block explorer reported,
+// shaped as balances.js writes it onto state.
+function walletsHolding(token, decimals) {
+    return [
+        {
+            name: "Wallet 1",
+            addresses: [
+                {
+                    address: "0x" + "a".repeat(40),
+                    balance: "1.0",
+                    tokenBalances: [
+                        {
+                            address: token,
+                            symbol: "NOVEL",
+                            decimals,
+                            balance: "1000.0",
+                        },
+                    ],
+                },
+            ],
+        },
+    ];
+}
+
+// The swap detail line as the approval screen renders it. It goes through
+// decodeCalldata() rather than uniswap.decode() directly, because the scale
+// sources the screen supplies are part of what is under test.
+function swapDetail(data, label) {
+    const decoded = decodeCalldata(data, ROUTER);
+    return decoded.details.find((d) => d.label === label);
+}
+
+beforeEach(() => {
+    state.trackedTokens = [];
+    state.wallets = [];
+});
+
+describe("a swap of a token outside the bundled list", () => {
+    const data = () => swapData(NOVEL, THOUSAND_AT_SIX, WETH, HALF_WETH);
+
+    test("shows the true quantity when the user tracks the token", () => {
+        state.trackedTokens = [
+            { address: NOVEL, symbol: "NOVEL", decimals: 6 },
+        ];
+        expect(swapDetail(data(), "Amount").value).toBe("1000.0000");
+    });
+
+    test("shows the true quantity from the explorer's decimals", () => {
+        state.wallets = walletsHolding(NOVEL, "6");
+        expect(swapDetail(data(), "Amount").value).toBe("1000.0000");
+    });
+
+    test("refuses to format when nothing knows the scale", () => {
+        const detail = swapDetail(data(), "Amount");
+        expect(detail.value).toBe("1000000000 base units (decimals unknown)");
+        expect(detail.value).toBe(unknownDecimalsAmount(THOUSAND_AT_SIX));
+        // The defect: an 18-decimal guess renders this swap as 0.000000001, a
+        // quantity, and a wrong one.
+        expect(detail.value).not.toMatch(/^0\./);
+        expect(detail.value).not.toMatch(/[0-9]\.[0-9]/);
+    });
+
+    test("the amount carried to the status screens is the same refusal", () => {
+        expect(swapDetail(data(), "Amount").rawValue).toBe(
+            "1000000000 base units (decimals unknown)",
+        );
+    });
+
+    test("a bundled token on the other side still formats", () => {
+        expect(swapDetail(data(), "Min. received").value).toBe("0.5000 WETH");
+    });
+});
+
+describe("the Min. received line takes the same rule", () => {
+    test("refuses to format an output token of unknown scale", () => {
+        const data = swapData(WETH, HALF_WETH, NOVEL_OUT, THOUSAND_AT_SIX);
+        const detail = swapDetail(data, "Min. received");
+        expect(detail.value).toBe("1000000000 base units (decimals unknown)");
+        expect(detail.value).not.toMatch(/[0-9]\.[0-9]/);
+    });
+
+    test("shows the true quantity when the user tracks the output token", () => {
+        state.trackedTokens = [
+            { address: NOVEL_OUT, symbol: "NOVEL", decimals: 6 },
+        ];
+        const data = swapData(WETH, HALF_WETH, NOVEL_OUT, THOUSAND_AT_SIX);
+        expect(swapDetail(data, "Min. received").value).toBe("1000.0000");
+    });
+});
+
+describe("the permit amount takes the same rule", () => {
+    // PERMIT2_PERMIT (command 0x0a): the input token and amount come from the
+    // permit rather than from a swap step.
+    function permitData(token, amount) {
+        const input = coder.encode(
+            [
+                "tuple(tuple(address,uint160,uint48,uint48),address,uint256)",
+                "bytes",
+            ],
+            [[[token, amount, 0, 0], ROUTER, 9999999999], "0x1234"],
+        );
+        return routerIface.encodeFunctionData("execute", [
+            "0x0a",
+            [input],
+            9999999999n,
+        ]);
+    }
+
+    test("refuses to format a permit on a token of unknown scale", () => {
+        const detail = swapDetail(permitData(NOVEL, THOUSAND_AT_SIX), "Amount");
+        expect(detail.value).toBe("1000000000 base units (decimals unknown)");
+    });
+
+    test("an unbounded permit is still named, with or without a scale", () => {
+        const maxUint160 = (1n << 160n) - 1n;
+        expect(swapDetail(permitData(NOVEL, maxUint160), "Amount").value).toBe(
+            "Unlimited",
+        );
+    });
+});

tests/version.test.js

@@ -0,0 +1,97 @@
+// One version, three files, and the rule that they agree.
+//
+// package.json, manifest/chrome.json and manifest/firefox.json each declare a
+// version and none is derived from another. Before this, nothing compared
+// them: the manifests were hardcoded at 0.1.0 and copied to dist/ verbatim
+// while package.json fed the About screen separately, so the number the
+// browser reported and the number the extension displayed could drift apart
+// with no check anywhere failing.
+//
+// The build enforces the agreement (build.js calls resolveVersion before it
+// emits anything) and script/lib/package.js names the artifacts from it. This
+// asserts both halves: that the tree as committed agrees, and that a tree that
+// does not is refused rather than resolved to one of the answers.
+
+const fs = require("fs");
+const os = require("os");
+const path = require("path");
+
+const {
+    VERSION_SOURCES,
+    declaredVersions,
+    resolveVersion,
+} = require("../script/lib/version");
+
+const ROOT = path.join(__dirname, "..");
+
+// A tree containing only the three version files, with the given versions.
+function fixture(versions) {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), "autistmask-version-"));
+    fs.mkdirSync(path.join(dir, "manifest"));
+    VERSION_SOURCES.forEach((source, i) => {
+        fs.writeFileSync(
+            path.join(dir, source),
+            JSON.stringify({ version: versions[i] }),
+        );
+    });
+    return dir;
+}
+
+describe("the declared version", () => {
+    test("all three sources agree in this tree", () => {
+        const declared = declaredVersions(ROOT);
+        expect(declared.map((d) => d.source)).toEqual(VERSION_SOURCES);
+        expect([...new Set(declared.map((d) => d.version))]).toHaveLength(1);
+        expect(resolveVersion(ROOT)).toBe(declared[0].version);
+    });
+
+    // Semver-shaped, because it names every release artifact and is what the
+    // browser compares when deciding whether an install is an upgrade.
+    test("is semver-shaped", () => {
+        expect(resolveVersion(ROOT)).toMatch(/^\d+\.\d+\.\d+$/);
+    });
+
+    // The load-bearing case: each of the three, disagreeing on its own, has to
+    // fail. A check that only looked at two of them would pass one of these.
+    test.each([
+        ["package.json", ["9.9.9", "0.1.0", "0.1.0"]],
+        ["manifest/chrome.json", ["0.1.0", "9.9.9", "0.1.0"]],
+        ["manifest/firefox.json", ["0.1.0", "0.1.0", "9.9.9"]],
+    ])("a disagreeing %s fails rather than resolving", (source, versions) => {
+        const dir = fixture(versions);
+        try {
+            expect(() => resolveVersion(dir)).toThrow(
+                /the declared versions disagree/,
+            );
+            expect(() => resolveVersion(dir)).toThrow(new RegExp(source));
+        } finally {
+            fs.rmSync(dir, { recursive: true, force: true });
+        }
+    });
+
+    test("agreeing sources resolve", () => {
+        const dir = fixture(["1.2.3", "1.2.3", "1.2.3"]);
+        try {
+            expect(resolveVersion(dir)).toBe("1.2.3");
+        } finally {
+            fs.rmSync(dir, { recursive: true, force: true });
+        }
+    });
+
+    // A missing or empty version is not agreement. Left unchecked, three files
+    // that all declared nothing would "agree" on undefined and the artifacts
+    // would be named after it.
+    test.each([[undefined], [""], ["   "], [3]])(
+        "a version of %p is refused",
+        (bad) => {
+            const dir = fixture([bad, bad, bad]);
+            try {
+                expect(() => resolveVersion(dir)).toThrow(
+                    /declares no usable "version"/,
+                );
+            } finally {
+                fs.rmSync(dir, { recursive: true, force: true });
+            }
+        },
+    );
+});