chore: bring the token-list enrichment tooling into script/lib (closes #495)

The two node programs and the data file from f7a2437 regenerate the name and
url of each token in src/shared/tokenList.js. They are now CommonJS under
script/lib/, find their files from their own location, and read
ethereum-lists at a pinned commit. The apply step also rewrites an entry that
already has a name and url, so it runs on the current list; on the committed
data it leaves the list unchanged. make enrich-tokens and make
apply-enrichment run them, and README.md names both targets. The data file
carries the MUSD token's on-chain name, so script/check-censored allows that
one literal there too.

Model: opus-5-5

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 package vendor-blocklist icons 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 icons enrich-tokens apply-enrichment clean dev
 
 # Standard targets are thin shims; the implementations live in script/
 # per the scripts-to-rule-them-all pattern (see the Entrypoints section
@@ -111,6 +111,17 @@ vendor-blocklist:
 icons:
 	@node script/lib/icons.js
 
+# Fetch a name and a website for every token in src/shared/tokenList.js into
+# script/lib/token-enrichment.json. Run deliberately, land the diff: the names
+# come from live data, so a later run can return different ones.
+enrich-tokens:
+	@node script/lib/enrich-tokens.js
+
+# Write the names and websites in script/lib/token-enrichment.json into
+# src/shared/tokenList.js. Commit the result with the data file.
+apply-enrichment:
+	@node script/lib/apply-enrichment.js
+
 clean:
 	@rm -rf dist/ release/
 

README.md

@@ -239,18 +239,24 @@ provide:
   `make check` stays non-mutating. Linting runs only in the container, because
   an ESLint result that depends on whichever ESLint the host happens to have is
   not a result, so docker is required to lint.
-- `script/fmt` — format all files (writes), on the host
-- `script/fmt-check` — check formatting (read-only), on the host
+- `script/fmt` — format all files (writes), on the host, with the `prettier`
+  that `script/bootstrap` installs in `node_modules/`; when that one is missing
+  it fails and says to run `script/bootstrap`, instead of using a `prettier`
+  from the `PATH`
+- `script/fmt-check` — check formatting (read-only), on the host, with the same
+  `prettier` and the same refusal
 - `script/check` — run `script/test`, `script/lint` and `script/fmt-check`
 - `script/check-censored` — assert the competitor name RULES.md bars appears
   nowhere in the working tree or under `dist/` outside its documented
   exceptions: the pinned source reference in `script/vendor-blocklist`, the two
   provider-shim identifiers in `src/content/inpage.js`, and one ERC-20's
-  on-chain name in `src/shared/tokenList.js`. Each is scoped to that path and
-  fails anywhere else. Run by the `lint` phase, so part of `make check`; it
-  inspects `dist/` when there is one and says loudly when there is not, and the
-  build context of that phase never has one. `make build` re-runs it with
-  `--require-dist`, so a build artifact is always covered
+  on-chain name in `src/shared/tokenList.js` and in
+  `script/lib/token-enrichment.json`, the fetched data that file's names are
+  written from. Each is scoped to the paths named and fails anywhere else. Run
+  by the `lint` phase, so part of `make check`; it inspects `dist/` when there
+  is one and says loudly when there is not, and the build context of that phase
+  never has one. `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,
@@ -322,6 +328,17 @@ The Makefile shims to those. It also carries a few targets that have no
   that already holds the drawn image, the same IHDR and every pixel, is left
   untouched. Commit the files with the drawing: `make check` fails while their
   image differs from what it draws
+- `make enrich-tokens` — fetch the name of each token in
+  `src/shared/tokenList.js` from CoinGecko's coin list and its website from the
+  `ethereum-lists/tokens` repository, at a pinned commit, into
+  `script/lib/token-enrichment.json`, by running `script/lib/enrich-tokens.js`.
+  CoinGecko's list is live and has no fixed version, so a later run can return
+  different names
+- `make apply-enrichment` — write the names and URLs in
+  `script/lib/token-enrichment.json` into `src/shared/tokenList.js`, by running
+  `script/lib/apply-enrichment.js`, taking a URL from the table of project
+  websites in that script only where the fetched data has none. Neither target
+  changes which tokens are on the list, and no build or `make check` runs either
 - `make clean` — remove `dist/` and `release/`
 - `make dev` — run the build `make build` runs, without the checks that follow
   it, then run it again after every change to a file under `src/`, `manifest/`
@@ -422,11 +439,12 @@ captured at `eth_sendRawTransaction` rather than against anything the extension
 reported, rejecting each prompt is required to return a rejection to the page
 rather than hang or resolve, a network switch request is required to leave the
 stored network unchanged and send no `chainChanged` until it is approved, a
-prompt raised while another approval window has focus is required to open a
-window of its own, and the password is required to be absent from every message
-the approval window sends to the background — with the message that would carry
-it required to be present, so that check cannot pass by observing nothing. That
-last one is the standing floor under
+network switch in Settings is required to send the page `chainChanged` with the
+new chain id, a prompt raised while another approval window has focus is
+required to open a window of its own, and the password is required to be absent
+from every message the approval window sends to the background — with the
+message that would carry it required to be present, so that check cannot pass by
+observing nothing. That last one is the standing floor under
 [#157](https://git.eeqj.de/sneak/AutistMask/issues/157).
 
 The limits of that coverage and of the rest of the Chrome suite, none of them
@@ -1789,7 +1807,8 @@ view would leave a wallet one click from deletion.
       network changes only here, or when the user approves a site's request on
       **NetworkApproval**; either way, switching restores the RPC and Blockscout
       endpoints last used on that network, or that network's defaults if it has
-      none
+      none, and sends `chainChanged` with the new chain id to every open tab.
+      Choosing the network already active changes nothing and sends nothing
     - Ethereum RPC: endpoint URL input + "Save" button (validated against
       `eth_chainId` before being saved)
     - Blockscout API: endpoint URL input + "Save" button (validated against
@@ -2158,6 +2177,13 @@ view would leave a wallet one click from deletion.
     - Typed data that states no primary type, or one other than the type it
       would be signed as, or that cannot be read → shown with the error line
       saying so and "Sign" disabled; only "Reject" remains
+    - Typed data whose domain `chainId` names a chain other than the active
+      network's → shown with the error line naming both chain ids and "Sign"
+      disabled; only "Reject" remains. EIP-712 asks for this, because the
+      signature is valid on the chain the domain names. Typed data with no
+      `chainId` is not refused. The background refuses such a signature too,
+      against the network active when the signature reaches it, and answers the
+      site with the same sentence
     - A `personal_sign` or `eth_sign` message that is not hex (`0x` or `0X` and
       an even number of hex digits, the form ethers' `getBytes` reads when
       signing) → shown as plain text, with the error line "This message is plain
@@ -2760,7 +2786,7 @@ exact URL, the commit it is pinned to and the sha256 of the bytes that commit
 serves, because a source reference nobody can verify is not a source reference.
 `script/check-censored` reads the name back out of that one file and fails the
 build wherever else it appears, save for three shipped-code literals it cannot
-avoid — each permitted only at the one path that carries it, and listed in that
+avoid — each permitted only at the paths that carry it, and listed in that
 script's header.
 
 ## Author

TODO.md

@@ -2,10 +2,9 @@
 
 - `git pull` `next` and cut a branch from it — one branch per issue, named
   `issue-<N>-<slug>`. Never branch from `main`.
-- Do the work as one commit whose title ends with ` (closes #N)`, with the
-  `TODO.md` update in that same commit.
-- Move Next Step to the top of Completed Steps; move the top item of Future
-  Steps into Next Step.
+- Do the work as one commit whose title ends with ` (closes #N)`.
+- Add no entry to Completed Steps. What landed is recorded on the tracker and in
+  `git log`, where each commit title names the issue it closes.
 - Run `make fmt`, then `make check`. A feature branch may be red; `next` and
   `main` may not.
 - Rebase onto current `next` immediately before pushing — other branches land on
@@ -44,6 +43,25 @@ then continue tagging as milestones land.
 
 # Completed Steps
 
+- 2026-10-08: The browser suites no longer read a screen before the page has
+  shown it ([#502](https://git.eeqj.de/sneak/AutistMask/issues/502)). Their wait
+  for a screen used to pass as soon as the element laid out, which every view
+  does until the page's stylesheet has applied, so an approval test could read
+  the prompt's fields before the page's script had filled them. `visible()` in
+  `tests/e2e/harness.js` and `waitVisible()` in `tests/e2e/firefox/driver.js`
+  now also wait for the page to finish loading and for neither the element nor
+  anything around it to carry the `hidden` class that `showView()` puts on every
+  view but the current one. No caller changed.
+
+- 2026-10-08: Switching the network in Settings now tells open pages
+  ([#500](https://git.eeqj.de/sneak/AutistMask/issues/500)). Once the switch is
+  saved, Settings asks the background to send `chainChanged` with the new chain
+  id to every open tab, through the same function an approved site request uses.
+  Choosing the network already active changes nothing and sends nothing. Only
+  the extension's own pages can ask for this. `tests/chainSwitchGate.test.js`
+  drives the real Settings view against the background, and the Chrome suite
+  checks that the test page hears both switches.
+
 - 2026-10-07: A site can no longer switch the wallet's network by itself
   ([#408](https://git.eeqj.de/sneak/AutistMask/issues/408)). A connected site's
   `wallet_switchEthereumChain` request for the other supported network opens a

script/check-censored

@@ -18,6 +18,8 @@
 #     (src/shared/balances.js), and this contract's on-chain name is that
 #     string, so censoring the repo cannot stop the wallet displaying it.
 #     Dropping the entry instead would cost the user MUSD spoof detection.
+#     script/lib/token-enrichment.json, the fetched data tokenList.js's names
+#     are written from, carries the same name for the same reason.
 #
 # Everything else fails, in the working tree and under dist/. The last two are
 # literals rather than whole files, so they are enforced by counting, and each
@@ -102,8 +104,8 @@ allowed_literals_for() {
     src/content/inpage.js | dist/*/src/content/inpage.js)
         printf 'is%s\n_%s\n' "$NAME" "$NAME" >"$ALLOWED_LITERALS_FILE"
         ;;
-    src/shared/tokenList.js | dist/*/src/background/index.js | \
-        dist/*/src/popup/index.js)
+    src/shared/tokenList.js | script/lib/token-enrichment.json | \
+        dist/*/src/background/index.js | dist/*/src/popup/index.js)
         printf '%s USD\n' "$NAME" >"$ALLOWED_LITERALS_FILE"
         ;;
     esac

script/fmt

@@ -25,6 +25,13 @@ run_yarn() {
 
 main() {
     cd "$ROOT"
+    # Without the repo's own prettier, yarn runs whatever prettier is on
+    # the PATH, which may be a version that formats files differently.
+    if [ ! -x node_modules/.bin/prettier ]; then
+        echo "fmt: this repo's prettier is not installed in node_modules/," \
+            "so run script/bootstrap first." >&2
+        exit 1
+    fi
     echo "Formatting..."
     run_yarn run fmt
 }

script/fmt-check

@@ -26,6 +26,13 @@ run_yarn() {
 
 main() {
     cd "$ROOT"
+    # Without the repo's own prettier, yarn runs whatever prettier is on
+    # the PATH, which may be a version that formats files differently.
+    if [ ! -x node_modules/.bin/prettier ]; then
+        echo "fmt-check: this repo's prettier is not installed in" \
+            "node_modules/, so run script/bootstrap first." >&2
+        exit 1
+    fi
     echo "Checking formatting..."
     run_yarn run fmt-check
 }

script/lib/apply-enrichment.js

@@ -0,0 +1,179 @@
+// Writes the names and URLs in script/lib/token-enrichment.json, which
+// script/lib/enrich-tokens.js fetches, into the matching entries of
+// src/shared/tokenList.js: the name and url an entry already has are replaced,
+// and an entry without them gets them after its decimals. Where the fetched
+// data has no URL for a token, EXTRA_URLS below supplies one if it lists the
+// token's address spelled exactly as tokenList.js spells it, capitals included.
+// An entry the data does not mention is left as it is. Run by
+// `make apply-enrichment`; no build runs it.
+
+"use strict";
+
+const fs = require("fs");
+const path = require("path");
+
+const TOKEN_LIST = path.join(__dirname, "..", "..", "src/shared/tokenList.js");
+
+const enrichment = JSON.parse(
+    fs.readFileSync(path.join(__dirname, "token-enrichment.json"), "utf8"),
+);
+
+// Project websites by token address. A token gets its URL here only where the
+// fetched data has none; an address the data has a URL for, or that is not on
+// the token list, is never used. An address matches only as tokenList.js spells
+// it, capitals included: the FLOKI, TURBO and MANA entries use other capitals
+// and never match, so FLOKI and TURBO have no URL.
+const EXTRA_URLS = {
+    "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2": "https://weth.io",
+    "0xdAC17F958D2ee523a2206206994597C13D831ec7": "https://tether.to",
+    "0xB8c77482e45F1F44dE1745F52C74426C631bDD52": "https://www.bnbchain.org",
+    "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48": "https://www.circle.com/usdc",
+    "0xdC035D45d973E3EC169d2276DDab16f1e407384F": "https://sky.money",
+    "0x2AF5D2aD76741191D15Dfe7bF6aC92d4Bd912Ca3": "https://www.bitfinex.com",
+    "0x514910771AF9Ca656af840dff83E8264EcF986CA": "https://chain.link",
+    "0x4c9EDD5852cd905f086C759E8383e09bff1E68B3": "https://ethena.fi",
+    "0x8d0D000Ee44948FC98c9B98A4FA4921476f08B0d":
+        "https://www.worldlibertyfinancial.com",
+    "0x6B175474E89094C44Da98b954EedeAC495271d0F": "https://makerdao.com",
+    "0x6c3ea9036406852006290770BEdFcAbA0e23A0e8":
+        "https://www.paypal.com/us/digital-wallet/manage-money/crypto/pyusd",
+    "0x95aD61b0a150d79219dCF64E1E6Cc01f0B64C4cE": "https://shibatoken.com",
+    "0xdA5e1988097297dCdc1f90D4dFE7909e847CBeF6":
+        "https://www.worldlibertyfinancial.com",
+    "0xA0b73E1Ff0B80914AB6fe0444E65848C4C34450b": "https://crypto.com",
+    "0x582d872A1B094FC48F5DE31D3B73F2D9bE47def1": "https://ton.org",
+    "0x68749665FF8D2d112Fa859AA293F07A622782F38": "https://gold.tether.to",
+    "0x196C20DA81Fbc324EcdF55501e95Ce9f0bD84d14": "https://polkadot.network",
+    "0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984": "https://uniswap.org",
+    "0x45804880De22913dAFE09f4980848ECE6EcbAf78":
+        "https://www.paxos.com/paxgold",
+    "0x3c3a81e81dc49A522A592e7622A7E711c06bf354": "https://www.mantle.xyz",
+    "0x7Fc66500c84A76Ad7e9c93437bFc5Ac33E2DDaE9": "https://aave.com",
+    "0x75231F58b43240C9718Dd58B4967c5114342a86c": "https://www.okx.com",
+    "0x6982508145454Ce325dDbE47a25d4ec3d2311933": "https://www.pepe.vip",
+    "0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599": "https://wbtc.network",
+    "0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84": "https://lido.fi",
+    "0x5A98FcBEA516Cf06857215779Fd812CA3beF1B32": "https://lido.fi",
+    "0xC18360217D8F7Ab5e7c516566761Ea12Ce7F9D72": "https://ens.domains",
+    "0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0": "https://polygon.technology",
+    "0x9f8F72aA9304c8B593d555F12eF6589cC3A579A2": "https://makerdao.com",
+    "0xD533a949740bb3306d119CC777fa900bA034cd52": "https://curve.fi",
+    "0x111111111117dC0aa78b770fA6A738034120C302": "https://1inch.io",
+    "0x163f8C2467924be0ae7B5347228CABF260318753": "https://worldcoin.org",
+    "0xba100000625a3754423978a60c9317c58a424e3D": "https://balancer.fi",
+    "0xC011a73ee8576Fb46F5E1c5751cA3B9Fe0af2a6F": "https://synthetix.io",
+    "0x1a7e4e63778B4f12a199C062f3eFdD288afCBce8": "https://www.euler.finance",
+    "0xBBbbCA6A901c926F240b89EacB641d8Aec7AEafD": "https://loopring.org",
+    "0xC669928185DbCE49d2230CC9B0979BE6DC797957": "https://bitstable.finance",
+    "0x7f39C581F595B53c5cb19bD0b3f8dA6c935E2Ca0": "https://lido.fi",
+    "0xBe9895146f7AF43049ca1c1AE358B0541Ea49704":
+        "https://www.coinbase.com/cbeth",
+    "0xfAbA6f8e4a5E8Ab82F62fe7C39859FA577269BE3": "https://ondo.finance",
+    "0x0C10bF8FcB7Bf5412187A595ab97a3609160b5c6": "https://decentraland.org",
+    "0x6De037ef9aD2725EB40118Bb1702EBb27e4Aeb24": "https://www.render.com",
+    "0x4a220E6096B25EADb88358cb44068A3248254675": "https://www.quant.network",
+    "0xba5BDe662c17e2aDFF1075610382B9B691296350": "https://superrare.com",
+    "0x15D4c048F83bd7e37d49eA4C83a07267Ec4203dA": "https://galxe.com",
+    "0xc00e94Cb662C3520282E6f5717214004A7f26888": "https://compound.finance",
+    "0xE41d2489571d322189246DaFA5ebDe1F4699F498": "https://0x.org",
+    "0x0bc529c00C6401aEF6D220BE8C6Ea1667F6Ad93e": "https://yearn.fi",
+    "0x6fB3e0A217407EFFf7Ca062D46c26E5d60a14d69": "https://iotex.io",
+    "0xD31a59c85aE9D8edEFec411D448f90841571b89c": "https://solana.com",
+    "0xa1faa113cbE53436Df28FF0aEe54275c13B40975": "https://alphafinance.io",
+    "0xF57e7e7C23978C3cAEC3C3548E3D615c346e79fF": "https://immutable.com",
+    "0x0f5D2fB29fb7d3CFeE444a200298f468908cC942": "https://decentraland.org",
+    "0x3845badAde8e6dFF049820680d1F14bD3903a5d0": "https://www.sandbox.game",
+    "0x4d224452801ACEd8B2F0aebE155379bb5D594381": "https://apecoin.com",
+    "0x6810e776880C02933D47DB1b9fc05908e5386b96": "https://gnosis.io",
+    "0x5f98805A4E8be255a32880FDeC7F6728C6568bA0": "https://www.liquity.org",
+    "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07": "https://omg.network",
+    "0x0D8775F648430679A709E98d2b0Cb6250d2887EF":
+        "https://basicattentiontoken.org",
+    "0xc944E90C64B2c07662A292be6244BDf05Cda44a7": "https://thegraph.com",
+    "0x1985365e9f78359a9B6AD760e32412f4a445E862": "https://augur.net",
+    "0x4E15361FD6b4BB609Fa63C81A2be19d873717870": "https://fantom.foundation",
+    "0x853d955aCEf822Db058eb8505911ED77F175b99e": "https://frax.finance",
+    "0x0000000000085d4780B73119b644AE5ecd22b376": "https://www.trueusd.com",
+    "0x0cEC1A9154Ff802e7934Fc916Ed7Ca50bDE6844e": "https://polymesh.network",
+    "0x956F47F50A910163D8BF957Cf5846D573E7f87CA": "https://fei.money",
+    "0x3432B6A60D23Ca0dFCa7761B7ab56459D9C964D0": "https://frax.finance",
+    "0xf939E0A03FB07F59A73314E73794Be0E57ac1b4E": "https://curve.fi",
+    "0x0100546F2cD4C9D97f798fFC9755E47865FF7Ee6": "https://alchemix.fi",
+    "0x808507121B80c02388fAd14726482e061B8da827": "https://pendle.finance",
+    "0xCa14007Eff0dB1f8135f4C25B34De49AB0d42766": "https://starknet.io",
+    "0x8457CA5040ad67fdebbCC8EdCE889A335Bc0fbFB": "https://alt.layer",
+    "0x4C19596f5aAfF459fA38B0f7eD92F11AE6543784": "https://www.truflation.com",
+    "0xB50721BCf8d664c30412Cfbc6cf7a15145234ad1": "https://arbitrum.io",
+    "0x912CE59144191C1204E64559FE8253a0e49E6548": "https://arbitrum.io",
+    "0x6985884C4392D348587B19cb9eAAf157F13271cd": "https://layerzero.network",
+    "0xFe0c30065B384F05761f15d0CC899D4F9F9Cc0eB": "https://ethfi.org",
+    "0x18084fbA666a33d37592fA2633fD49a74DD93a88": "https://tbtc.network",
+    "0x9D39A5DE30e57443BfF2A8307A4256c8797A3497": "https://suilend.fi",
+    "0x5283D291DBCF85356A21bA090E6db59121208b44": "https://blur.io",
+    "0x43Dfc4159D86F3A37A5A4B3D4580b888ad7d4DDd": "https://dydx.exchange",
+    "0xCf0C122c6b73ff809C693DB761e7BaeBe62b6a2E": "https://floki.com",
+    "0xe53EC727dbDEB9E2d5456c3be40cFF031AB40A55": "https://superfarm.com",
+    "0x32353A6C91143bfd6C7d363B546e62a9A2489A20": "https://www.agora.finance",
+    "0x1aBaEA1f7C830bD89Acc67eC4af516284b1bC33c": "https://www.euro-coin.com",
+    "0x1a03eF3d1a80b5f214e468ACD97F55714E049393": "https://gemspad.io",
+    "0x7122985656e38BDC0302Db86685bb972b145bD3C": "https://stone.fi",
+    "0xa35923162C49cF95e6BF26623385eb431ad920D3": "https://www.turbo-eth.com",
+    "0xdBdb4d16EdA451D0503b854CF79D55697F90c8DF": "https://alchemix.fi",
+    "0x08c32b0726C5684024ea6e141C50aDe9690bBdcc": "https://stratis.io",
+    "0x65Ef703f5594D2573eb71Aaf55BC0CB548492df4": "https://multichain.org",
+    "0x1151CB3d861920e07a38e03eEAd12C32178567F6": "https://bonk.com",
+    "0x090185f2135308BaD17527004364eBcC2D37e5F6": "https://spell.club",
+    "0xAf5191B0De278C7286d6C7CC6ab6BB8A73bA2Cd6": "https://stargate.finance",
+};
+
+// Apply extra URLs where enrichment has none
+for (const [addr, url] of Object.entries(EXTRA_URLS)) {
+    const e = enrichment[addr];
+    if (e && !e.url) {
+        e.url = url;
+    }
+}
+
+// Read original tokenList.js
+const original = fs.readFileSync(TOKEN_LIST, "utf8");
+
+// Replace each token block: name and url after decimals
+let result = original;
+let replacements = 0;
+
+for (const [addr, data] of Object.entries(enrichment)) {
+    // Escape special regex characters in the address
+    const escaped = addr.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+
+    // Match the token block: { address: "...", symbol: "...", decimals: N, }
+    // and the name: "...", url: "..." after decimals when it has them.
+    // The closing }, may have trailing whitespace
+    const blockRe = new RegExp(
+        `(\\{\\s*address:\\s*"${escaped}",\\s*symbol:\\s*"[^"]+",\\s*decimals:\\s*\\d+)` +
+            `(?:,\\s*name:\\s*"(?:[^"\\\\]|\\\\.)*",\\s*url:\\s*"(?:[^"\\\\]|\\\\.)*")?` +
+            `,?(\\s*\\})`,
+    );
+
+    const match = result.match(blockRe);
+    if (!match) {
+        console.error(`WARNING: Could not find block for ${addr}`);
+        continue;
+    }
+
+    // Build replacement: original fields + name + url
+    const nameEscaped = data.name.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
+    const urlEscaped = data.url.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
+    const replacement =
+        match[1] +
+        `,\n        name: "${nameEscaped}",` +
+        `\n        url: "${urlEscaped}",` +
+        match[2];
+
+    // A function, so a "$" in a name is not read as a replacement pattern.
+    result = result.replace(blockRe, () => replacement);
+    replacements++;
+}
+
+console.error(`Applied ${replacements} enrichments to tokenList.js`);
+fs.writeFileSync(TOKEN_LIST, result);
+console.error("Done!");

script/lib/enrich-tokens.js

@@ -0,0 +1,115 @@
+// Fetches a name and a website for every token in src/shared/tokenList.js and
+// writes them, keyed by address, to script/lib/token-enrichment.json, which
+// script/lib/apply-enrichment.js then writes into tokenList.js. Run by
+// `make enrich-tokens`; no build runs it and nothing here is shipped.
+//
+// Names come from CoinGecko's coin list, fetched whole in one request, matched
+// on the token's Ethereum contract address. A token CoinGecko does not list
+// gets its symbol as its name. The list is live data with no fixed version, so
+// a later run can return different names.
+//
+// Websites come from the ethereum-lists/tokens repository, one file per token,
+// read at a pinned commit. Most tokens have no file there and get an empty URL.
+// A file that is missing is not an error; any other failed request stops the
+// run, so a network fault cannot quietly empty a URL.
+
+"use strict";
+
+const fs = require("fs");
+const path = require("path");
+
+const TOKEN_LIST = path.join(__dirname, "..", "..", "src/shared/tokenList.js");
+const OUTPUT = path.join(__dirname, "token-enrichment.json");
+
+const COINGECKO_LIST =
+    "https://api.coingecko.com/api/v3/coins/list?include_platform=true";
+// ethereum-lists/tokens at its master of 2026-02-27, when the committed
+// token-enrichment.json was made.
+const ETHEREUM_LISTS =
+    "https://raw.githubusercontent.com/ethereum-lists/tokens/c3560d499a380a38e94caa7c4968d59aeffde59a/tokens/eth";
+
+const CONCURRENT = 10;
+
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+
+async function main() {
+    const src = fs.readFileSync(TOKEN_LIST, "utf8");
+
+    const tokens = [];
+    const re =
+        /\{\s*address:\s*"(0x[a-fA-F0-9]{40})",\s*symbol:\s*"([^"]+)",\s*decimals:\s*(\d+)/g;
+    let m;
+    while ((m = re.exec(src)) !== null) {
+        tokens.push({ address: m[1], symbol: m[2], decimals: parseInt(m[3]) });
+    }
+    console.error(`Parsed ${tokens.length} tokens`);
+
+    // --- Names from CoinGecko ---
+    console.error("Fetching CoinGecko coins list...");
+    const listResp = await fetch(COINGECKO_LIST);
+    if (!listResp.ok) throw new Error(`CoinGecko list HTTP ${listResp.status}`);
+    const coins = await listResp.json();
+
+    const addrMap = new Map();
+    for (const coin of coins) {
+        const eth = (coin.platforms?.ethereum || "").toLowerCase().trim();
+        if (eth && eth.startsWith("0x")) {
+            addrMap.set(eth, { name: coin.name, id: coin.id });
+        }
+    }
+    console.error(`CoinGecko map: ${addrMap.size} Ethereum tokens`);
+
+    const enriched = new Map();
+    let namesMatched = 0;
+    for (const t of tokens) {
+        const info = addrMap.get(t.address.toLowerCase());
+        if (info) namesMatched++;
+        enriched.set(t.address, { name: info?.name || t.symbol, url: "" });
+    }
+    console.error(`Matched ${namesMatched}/${tokens.length} names`);
+
+    // --- Websites from ethereum-lists ---
+    console.error("Fetching URLs from ethereum-lists GitHub...");
+    let urlsFound = 0;
+
+    for (let i = 0; i < tokens.length; i += CONCURRENT) {
+        const batch = tokens.slice(i, i + CONCURRENT);
+        await Promise.all(
+            batch.map(async (t) => {
+                const r = await fetch(`${ETHEREUM_LISTS}/${t.address}.json`);
+                if (r.status === 404) return;
+                if (!r.ok) {
+                    throw new Error(
+                        `ethereum-lists HTTP ${r.status} for ${t.address}`,
+                    );
+                }
+                const data = await r.json();
+                const website = (data.website || "").trim();
+                if (website && website !== "https://") {
+                    enriched.get(t.address).url = website;
+                    urlsFound++;
+                }
+            }),
+        );
+        if (i % 100 === 0) {
+            console.error(
+                `  GitHub: ${Math.min(i + CONCURRENT, tokens.length)}/${tokens.length}, ${urlsFound} URLs`,
+            );
+        }
+        await sleep(200);
+    }
+    console.error(`Found ${urlsFound} URLs in ethereum-lists`);
+
+    // --- Output, in the layout prettier gives it ---
+    const output = {};
+    for (const [addr, e] of enriched) {
+        output[addr] = { name: e.name, url: e.url };
+    }
+    fs.writeFileSync(OUTPUT, JSON.stringify(output, null, 4) + "\n");
+    console.error(`Done! ${tokens.length} names, ${urlsFound} URLs.`);
+}
+
+main().catch((err) => {
+    console.error(`enrich-tokens: ${err.message}`);
+    process.exit(1);
+});

src/background/index.js

@@ -22,6 +22,7 @@ const { debugFetch, log } = require("../shared/log");
 const {
     verifySignedTx,
     verifySignature,
+    typedDataChainRefusal,
     failureIsRetryable,
     describeTxFailure,
     sameAddress,
@@ -1471,6 +1472,7 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         "AUTISTMASK_ADDRESSES_REMOVED",
         "AUTISTMASK_GET_CONNECTED_SITES",
         "AUTISTMASK_REMOVE_SITE",
+        "AUTISTMASK_NETWORK_CHANGED",
     ];
     if (POPUP_ONLY_TYPES.includes(msg.type) && !isExtensionSender(sender)) {
         sendResponse({ error: "Unauthorized sender" });
@@ -1763,7 +1765,8 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
 
         (async () => {
             try {
-                const activeAddress = await getActiveAddress();
+                const s = await getState();
+                const activeAddress = activeAddressOf(s);
                 // Same as the transaction path: the address the approval named
                 // is the one that must have signed, and a switch since then is
                 // a refusal rather than a signature from another account.
@@ -1782,6 +1785,20 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
                     signature,
                     approval.approvedFrom,
                 );
+                // The sign screen refuses typed data whose domain names
+                // another chain. A signature for it that arrives anyway is
+                // refused here, against the network active now.
+                const sp = approval.signParams;
+                if (
+                    sp.method === "eth_signTypedData_v4" ||
+                    sp.method === "eth_signTypedData"
+                ) {
+                    const refusal = typedDataChainRefusal(
+                        JSON.parse(sp.typedData).domain,
+                        networkById(s.networkId),
+                    );
+                    if (refusal) throw new ApprovalMismatchError(refusal);
+                }
                 settleApproval(msg.id, { signature }, { holdsClaim: true });
                 sendResponse({ signature });
             } catch (e) {
@@ -1854,6 +1871,13 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         broadcastSiteRemoved(msg.origin);
         return false;
     }
+
+    // Settings switched the network and has saved it. Open tabs are told the
+    // new chain id the same way as after a site's approved switch request.
+    if (msg.type === "AUTISTMASK_NETWORK_CHANGED") {
+        broadcastChainChanged(msg.chainId);
+        return false;
+    }
 });
 
 module.exports = { PROXY_METHODS };

src/popup/index.html

@@ -7,9 +7,10 @@
         <link rel="stylesheet" href="styles.css" />
     </head>
     <!-- Chrome gives extension pages a stylesheet of its own that sets the
-         font on body, and a Tailwind class beats it only when marked
-         important: hence font-mono! rather than font-mono. -->
-    <body class="bg-bg text-fg font-mono! text-sm">
+         font and its size on body, and a Tailwind class beats it only when
+         marked important: hence font-mono! and text-sm! rather than
+         font-mono and text-sm. -->
+    <body class="bg-bg text-fg font-mono! text-sm!">
         <div id="app" class="p-2 pr-5 overflow-x-hidden">
             <!-- ============ GLOBAL TITLE BAR ============ -->
             <div
@@ -87,11 +88,14 @@
 
                 <!-- Mnemonic form section -->
                 <div id="add-wallet-section-mnemonic">
-                    <p class="mb-2">
-                        Enter your 12 or 24 word recovery phrase below, or click
-                        the button to roll the die for a new one.
-                    </p>
-                    <div class="mb-1 flex justify-end">
+                    <!-- The die button shares the instruction's row: on a row
+                         of its own it pushes Import below the fold at
+                         360x600. -->
+                    <div class="mb-2 flex justify-between items-start gap-2">
+                        <p>
+                            Enter your 12 or 24 word recovery phrase below, or
+                            click the button to roll the die for a new one.
+                        </p>
                         <button
                             id="btn-generate-phrase"
                             class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer text-xs"

src/popup/views/approval.js

@@ -12,7 +12,7 @@ const {
     formatFee,
     tokenLabel,
 } = require("./helpers");
-const { state, saveState } = require("../../shared/state");
+const { state, saveState, currentNetwork } = require("../../shared/state");
 const {
     networkById,
     networkByChainId,
@@ -46,7 +46,10 @@ const {
 const { decryptWithPassword } = require("../../shared/vault");
 const { getSignerForAddress } = require("../../shared/wallet");
 const { walletDefect } = require("../../shared/walletDefects");
-const { describeSigningFailure } = require("../../shared/approvalVerify");
+const {
+    describeSigningFailure,
+    typedDataChainRefusal,
+} = require("../../shared/approvalVerify");
 const txStatus = require("./txStatus");
 const uniswap = require("../../shared/uniswap");
 const { notify, runtimeApi, sendMessage } = require("../../shared/browserApi");
@@ -443,7 +446,8 @@ function signedPrimaryType(types) {
 // Why a signature request cannot be signed, as a sentence for the error line,
 // or null when it can. Only typed data is refused: the `primaryType` the page
 // states has to be the type ethers will sign, or this screen would name one
-// message while another is signed.
+// message while another is signed. Its domain may name no chain but the active
+// network's.
 function typedDataRefusal(sp) {
     if (sp.method === "personal_sign" || sp.method === "eth_sign") return null;
     let data;
@@ -466,7 +470,7 @@ function typedDataRefusal(sp) {
             ", so it cannot be signed."
         );
     }
-    return null;
+    return typedDataChainRefusal(data.domain, currentNetwork());
 }
 
 // The largest amount a Permit2 allowance can hold, a uint160. Permit2 treats

src/popup/views/settings.js

@@ -316,7 +316,11 @@ function init(ctx) {
     const networkSelect = $("settings-network");
     networkSelect.addEventListener("change", async () => {
         const newId = networkSelect.value;
+        if (newId === state.networkId) return;
         const net = await onChainSwitch(newId);
+        // Open pages are told by the background, as after a site's approved
+        // switch request.
+        notify({ type: "AUTISTMASK_NETWORK_CHANGED", chainId: net.chainId });
         $("settings-rpc").value = state.rpcUrl;
         $("settings-blockscout").value = state.blockscoutUrl;
         showFlash("Switched to " + net.name + ".");

src/shared/approvalVerify.js

@@ -53,6 +53,7 @@ const {
     accessListify,
     formatEther,
     getAddress,
+    getBigInt,
     getBytes,
     toQuantity,
     verifyMessage,
@@ -635,6 +636,33 @@ function verifySignature(signParams, signature, expectedFrom) {
     return recovered;
 }
 
+// Why typed data cannot be signed while `network` is the active network, as a
+// sentence, or null when it can. EIP-712 has a wallet refuse typed data whose
+// domain names another chain, because the signature is valid on that chain.
+// ethers signs no chain id when the domain's is null or absent, and reads any
+// other with getBigInt(), so 1, "1" and "0x1" are the same chain here too.
+function typedDataChainRefusal(domain, network) {
+    const chainId = domain?.chainId;
+    if (chainId === undefined || chainId === null) return null;
+    let named;
+    try {
+        named = getBigInt(chainId);
+    } catch {
+        return "This typed data cannot be read, so it cannot be signed.";
+    }
+    const active = getBigInt(network.chainId);
+    if (named === active) return null;
+    return (
+        "This typed data is for chain id " +
+        named +
+        ", but the active network is " +
+        network.name +
+        " (chain id " +
+        active +
+        "), so it cannot be signed."
+    );
+}
+
 // The stage a transaction approval failed at. Which stage it is decides
 // whether the approval survives the failure.
 const TX_STAGE_SIGN = "sign";
@@ -796,6 +824,7 @@ function describeSigningFailure(response, fallbackMessage) {
 module.exports = {
     verifySignedTx,
     verifySignature,
+    typedDataChainRefusal,
     assertNoForbiddenFields,
     assertNothingUnchecked,
     assertCanonicalBytes,

tests/backgroundApproval.test.js

@@ -397,7 +397,13 @@ function loadBackground(options) {
                 rpcResult = r;
             },
         );
-        return { result: () => rpcResult };
+        return {
+            id: () =>
+                new URL(created[created.length - 1].url).searchParams.get(
+                    "approval",
+                ),
+            result: () => rpcResult,
+        };
     }
 
     // A dApp asking to connect. The origin defaults to one the persisted
@@ -1484,6 +1490,55 @@ describe("what the approval is verified against", () => {
         });
     });
 
+    // Typed data whose domain names another chain is refused on the sign
+    // screen; a signature for it that reaches the background anyway is not
+    // handed to the page (https://git.eeqj.de/sneak/AutistMask/issues/519).
+    // TYPED_DATA names mainnet.
+    async function answerTypedData(bg, pending) {
+        const { domain, types, message } = JSON.parse(TYPED_DATA);
+        delete types.EIP712Domain;
+        const signature = await signer.signTypedData(domain, types, message);
+        const answer = bg.send(
+            {
+                type: "AUTISTMASK_SIGN_RESPONSE",
+                id: pending.id(),
+                approved: true,
+                signature,
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        return { answer, signature };
+    }
+
+    test("typed data for the active chain is handed back signed", async () => {
+        const bg = loadBackground();
+        const pending = bg.requestTypedData();
+        await settle();
+
+        const { answer, signature } = await answerTypedData(bg, pending);
+
+        expect(answer.sendResponse).toHaveBeenCalledWith({ signature });
+        expect(pending.result()).toEqual({ result: signature });
+    });
+
+    test("typed data for another chain is refused, not handed back", async () => {
+        const bg = loadBackground();
+        bg.setNetwork(SEPOLIA);
+        const pending = bg.requestTypedData();
+        await settle();
+
+        const { answer } = await answerTypedData(bg, pending);
+
+        const refusal =
+            "This typed data is for chain id 1, but the active network is Sepolia Testnet (chain id 11155111), so it cannot be signed.";
+        expect(answer.sendResponse).toHaveBeenCalledWith({
+            error: refusal,
+            retryable: false,
+        });
+        expect(pending.result()).toEqual({ error: { message: refusal } });
+    });
+
     test("a sign request from another address raises no approval at all", async () => {
         const bg = loadBackground();
         const pending = bg.requestSign(other.address);

tests/chainSwitchGate.test.js

@@ -16,7 +16,9 @@
 //
 // The endpoint half of #308 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.
+// goes through storage rather than the shared state singleton. The last block
+// covers what the background tells open tabs when the user switches the
+// network in Settings.
 
 const { networkById } = require("../src/shared/networks");
 const { makeStorageStub } = require("./support/storageStub");
@@ -225,6 +227,14 @@ function loadBackground() {
         answerPrompt,
         closePrompt,
         opened,
+        // A message to the background from `sender`, and its answer.
+        send: (msg, sender) => {
+            let reply = null;
+            messageListener(msg, sender, (r) => {
+                reply = r;
+            });
+            return reply;
+        },
         walletState: () => storage.read("autistmask"),
         chainChangedEvents: () =>
             toTabs.filter((m) => m.eventName === "chainChanged"),
@@ -390,3 +400,109 @@ describe("only the user switches the network", () => {
         expect(bg.walletState().rpcUrl).toBe(CUSTOM_RPC);
     });
 });
+
+// Switching the network in Settings tells open pages, as an approved site
+// request does (https://git.eeqj.de/sneak/AutistMask/issues/500). These drive
+// the real Settings view over the background's storage, with what it sends
+// delivered to the background from the extension's own page.
+describe("switching the network in Settings tells every open tab", () => {
+    const POPUP = { url: EXT_URL + "src/popup/index.html" };
+
+    // A stand-in for one DOM node: enough of an element for init() to set
+    // properties on it and hang listeners off it.
+    function fakeElement() {
+        return {
+            value: "",
+            checked: false,
+            textContent: "",
+            style: {},
+            dataset: {},
+            classList: { add() {}, remove() {} },
+            listeners: {},
+            addEventListener(event, handler) {
+                this.listeners[event] = handler;
+            },
+            querySelectorAll: () => [],
+        };
+    }
+
+    // Settings, opened the way the popup opens it. Returns its network
+    // selector.
+    async function openSettings(bg) {
+        const elements = {};
+        const element = (id) => (elements[id] ||= fakeElement());
+        jest.doMock("../src/popup/views/helpers", () => ({
+            $: element,
+            showView: () => {},
+            updateDebugBanner: () => {},
+            showFlash: () => {},
+            escapeHtml: (s) => s,
+            flashCopyFeedback: () => {},
+            goBack: () => {},
+            pushCurrentView: () => {},
+            onViewLeave: () => {},
+            VIEWS: [],
+        }));
+        global.chrome.runtime.sendMessage = (msg) => {
+            bg.send(msg, POPUP);
+        };
+        await require("../src/shared/state").loadState();
+        require("../src/popup/views/settings").init({
+            pageClosed: new AbortController().signal,
+        });
+        const select = element("settings-network");
+        select.value = "mainnet";
+        return select;
+    }
+
+    // The user picks `networkId` in the selector.
+    async function choose(select, networkId) {
+        select.value = networkId;
+        await select.listeners.change();
+        await settle();
+    }
+
+    afterEach(() => {
+        jest.dontMock("../src/popup/views/helpers");
+    });
+
+    test("switching to the other network sends chainChanged once, with its chain id", async () => {
+        const bg = loadBackground();
+        const select = await openSettings(bg);
+
+        await choose(select, "sepolia");
+
+        expect(bg.walletState().networkId).toBe("sepolia");
+        expect(bg.chainChangedEvents()).toEqual([
+            {
+                type: "AUTISTMASK_EVENT",
+                eventName: "chainChanged",
+                data: SEPOLIA.chainId,
+            },
+        ]);
+    });
+
+    test("choosing the network already active changes nothing and sends nothing", async () => {
+        const bg = loadBackground();
+        const select = await openSettings(bg);
+        const before = bg.walletState();
+
+        await choose(select, "mainnet");
+
+        expect(bg.walletState()).toEqual(before);
+        expect(bg.chainChangedEvents()).toEqual([]);
+    });
+
+    test("a page cannot make the background send chainChanged", async () => {
+        const bg = loadBackground();
+
+        const reply = bg.send(
+            { type: "AUTISTMASK_NETWORK_CHANGED", chainId: SEPOLIA.chainId },
+            { url: CONNECTED_ORIGIN + "/" },
+        );
+        await settle();
+
+        expect(reply).toEqual({ error: "Unauthorized sender" });
+        expect(bg.chainChangedEvents()).toEqual([]);
+    });
+});

tests/e2e/firefox/driver.js

@@ -279,12 +279,18 @@ class Driver {
 
     // Shown means shown: in the popup a view is switched by toggling a
     // "hidden" class, and an element that is present but collapsed is not
-    // the thing a test means by visible.
+    // the thing a test means by visible. Until the page's stylesheet has
+    // applied that class hides nothing and every view lays out, so the page
+    // must also have finished loading, which it does only after its
+    // stylesheet, and neither the element nor anything enclosing it may
+    // carry the class (https://git.eeqj.de/sneak/AutistMask/issues/502).
     async waitVisible(selector, timeout = DEFAULT_WAIT_MS) {
         return this.waitFor(
             "selector " + selector + " to be visible",
             `const el = document.querySelector(arguments[0]);
-             if (!el) return false;
+             if (document.readyState !== "complete" || !el) return false;
+             if (el.closest(".hidden")) return false;
+             if (getComputedStyle(el).visibility !== "visible") return false;
              const r = el.getBoundingClientRect();
              return r.width > 0 && r.height > 0;`,
             [selector],

tests/e2e/firefox/run.js

@@ -128,6 +128,18 @@ step("the popup is drawn in the monospace font it declares", async (env) => {
     );
 });
 
+// The same check as the Chrome suite's (#456), so both browsers are held to
+// the same size.
+step("the popup's text is drawn at the 14px text-sm declares", async (env) => {
+    const size = await env.driver.execute(
+        "return getComputedStyle(document.body).fontSize;",
+    );
+    assert(
+        size === "14px",
+        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
+    );
+});
+
 // The recovery screen (#361): the Chrome suite's four cases, run before any
 // wallet exists for the same reason. With no wallet nothing saves on a timer,
 // so no save can write a good record over the unreadable one. The last of them

tests/e2e/harness.js

@@ -333,8 +333,33 @@ async function launch(routeOpts) {
 
 const PASSWORD = "e2e-harness-password";
 
+// Waits until the page shows `selector`, not only until it lays out. Until the
+// page's stylesheet has applied, the `hidden` class that showView() keeps on
+// every view but the current one hides nothing and every view lays out, so a
+// test could read a screen before the page's script had filled it
+// (https://git.eeqj.de/sneak/AutistMask/issues/502). So the page must also
+// have finished loading, which it does only after its stylesheet, and neither
+// the element nor anything enclosing it may carry `hidden`. Polled on a timer:
+// animation frames are not guaranteed to a window that is not in front.
 async function visible(page, selector, timeout = 15000) {
-    await page.waitForSelector(selector, { state: "visible", timeout });
+    await page
+        .waitForFunction(
+            (sel) => {
+                const el = document.querySelector(sel);
+                if (document.readyState !== "complete" || !el) return false;
+                if (el.closest(".hidden")) return false;
+                if (getComputedStyle(el).visibility !== "visible") return false;
+                const r = el.getBoundingClientRect();
+                return r.width > 0 && r.height > 0;
+            },
+            selector,
+            { polling: 50, timeout },
+        )
+        .catch((e) => {
+            throw new Error(
+                "the page did not show " + selector + ": " + e.message,
+            );
+        });
 }
 
 // An empty WebAssembly module: magic number and version header, no

tests/e2e/run.js

@@ -113,6 +113,18 @@ test("the popup is drawn in the monospace font it declares (#418)", async (env)
     );
 });
 
+// The same stylesheet sets the size on body to 75%, which would draw the
+// popup at 12px.
+test("the popup's text is drawn at the 14px text-sm declares (#456)", async (env) => {
+    const size = await env.page.evaluate(
+        () => getComputedStyle(document.body).fontSize,
+    );
+    assert(
+        size === "14px",
+        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
+    );
+});
+
 // The empirical half of #182. The manifest change is only a claim about
 // what the CSP permits; this is the observation. Two things have to hold
 // together, and the run covers both: the popup realm compiles WASM (here),
@@ -4538,6 +4550,42 @@ test("a site's network switch changes nothing until the user approves it (#408)"
     );
 });
 
+// Switching the network in Settings tells the page too, as an approved site
+// request does (https://git.eeqj.de/sneak/AutistMask/issues/500). The wallet
+// goes back to mainnet the same way at the end.
+test("a network switch in Settings tells the page (#500)", async (env) => {
+    const { mainnet, sepolia } = NETWORKS;
+    const before = await storedNetwork(env.page);
+    assert(
+        before.networkId === "mainnet",
+        "this test starts on mainnet, not on " + before.networkId,
+    );
+    const eventsBefore = (await chainChangedEvents(env.dapp)).length;
+    await openSettings(env.page);
+
+    await env.page.selectOption("#settings-network", "sepolia");
+    let events = await chainChangedEvents(env.dapp, eventsBefore + 1);
+    assert(
+        events.length === eventsBefore + 1 &&
+            events[events.length - 1].data === sepolia.chainId,
+        "the page was not told of the switch to Sepolia: " +
+            JSON.stringify(events),
+    );
+
+    await env.page.selectOption("#settings-network", "mainnet");
+    events = await chainChangedEvents(env.dapp, eventsBefore + 2);
+    assert(
+        events.length === eventsBefore + 2 &&
+            events[events.length - 1].data === mainnet.chainId,
+        "the page was not told of the switch back to mainnet: " +
+            JSON.stringify(events),
+    );
+    assert(
+        isDeepStrictEqual(await storedNetwork(env.page), before),
+        "switching back did not restore the mainnet network and endpoints",
+    );
+});
+
 // The closing pass over both boundaries at once. Every message the section
 // put on either channel is re-read here and required to be free of the
 // password — and required to be there at all, method by method, so the

tests/typedDataPermit.test.js

@@ -240,6 +240,7 @@ function request(data) {
 beforeEach(() => {
     state.trackedTokens = [];
     state.wallets = [];
+    state.networkId = "mainnet";
 });
 
 describe("a token permission is warned about, naming spender and amount", () => {
@@ -532,3 +533,66 @@ describe("the sign screen refuses a mismatched primary type", () => {
         expect(node("btn-approve-sign").disabled).toBe(true);
     });
 });
+
+// EIP-712: a wallet refuses typed data whose domain names a chain other than
+// the active one, because the signature is valid on the chain it names
+// (https://git.eeqj.de/sneak/AutistMask/issues/519). The wallet is on Sepolia
+// and the site asks for a mainnet USDC Permit.
+describe("the sign screen refuses typed data for another chain", () => {
+    const REFUSAL =
+        "This typed data is for chain id 1, but the active network is Sepolia Testnet (chain id 11155111), so it cannot be signed.";
+
+    function withChainId(chainId) {
+        return { ...PERMIT, domain: { ...PERMIT.domain, chainId } };
+    }
+
+    beforeEach(() => {
+        decryptWithPassword.mockClear();
+        state.networkId = "sepolia";
+    });
+
+    test("another chain shows the error, with Sign disabled", async () => {
+        await openSignScreen(PERMIT);
+        expect(node("approve-sign-error").textContent).toBe(REFUSAL);
+        expect(node("btn-approve-sign").disabled).toBe(true);
+    });
+
+    test("Sign clicked anyway decrypts and signs nothing", async () => {
+        const sent = await openSignScreen(PERMIT);
+        node("approve-sign-password").value = "any password";
+        await click("btn-approve-sign");
+
+        expect(decryptWithPassword).not.toHaveBeenCalled();
+        expect(sent.map((msg) => msg.type)).not.toContain(
+            "AUTISTMASK_SIGN_RESPONSE",
+        );
+        expect(node("approve-sign-error").textContent).toBe(REFUSAL);
+    });
+
+    // ethers signs 1, "1" and "0x1" as the same chain id.
+    test("the chain id is refused in each form ethers signs", () => {
+        for (const chainId of [1, "1", "0x1"]) {
+            expect(typedDataRefusal(request(withChainId(chainId)))).toBe(
+                REFUSAL,
+            );
+        }
+    });
+
+    test("a chain id that is not a number is refused", () => {
+        expect(typedDataRefusal(request(withChainId("mainnet")))).toBe(
+            "This typed data cannot be read, so it cannot be signed.",
+        );
+    });
+
+    test("the active chain leaves Sign enabled", async () => {
+        await openSignScreen(withChainId("0xaa36a7"));
+        expect(node("approve-sign-error").textContent).toBe("");
+        expect(node("btn-approve-sign").disabled).toBe(false);
+    });
+
+    test("no chain id leaves Sign enabled", async () => {
+        await openSignScreen(withChainId(undefined));
+        expect(node("approve-sign-error").textContent).toBe("");
+        expect(node("btn-approve-sign").disabled).toBe(false);
+    });
+});