docs: state verify-build's dist/ guarantee at the width it enforces (closes #331)

check_dist_tree walks -type f -o -type l, so the emitted-tree cross-check covers
regular files and symlinks under dist/. README.md said "nothing under dist/ that
the build did not write", which is broader: fifos, sockets, device nodes and
empty directories are not checked.

The exclusion stays. A build emits none of those types, none can carry a
shippable payload, and grep on a fifo would hang rather than fail. README.md,
the script's header comment and the check_dist_tree comment now say so in the
same words, so the code and the docs cannot drift apart again.

Documentation only: no non-comment line of script/verify-build changed.

README.md

@@ -81,17 +81,21 @@ lives.
 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.
+requested `DEBUG` marker, and no regular file or symlink 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.
+output of the `build.js` run that just finished, with no regular file or symlink
+added, removed or altered in between. Regular files and symlinks are the whole
+of what the tree walk covers; fifos, sockets, device nodes and empty directories
+under `dist/` are not checked, because a build emits none of them, none can
+carry a shippable payload, and grep on a fifo would hang rather than fail. 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
@@ -143,16 +147,17 @@ 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 --expect release|debug --receipt PATH` — assert that
-  `dist/` is exactly what the build that just ran emitted, and that the compiled
-  `DEBUG` state of the bundles in it is the one that was asked for. Both
-  arguments are required and neither has a default: the expected mode is stated
-  by the caller rather than read from `AUTISTMASK_DEBUG`, and the file list
-  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/verify-build --expect release|debug --receipt PATH` — assert that the
+  regular files and symlinks under `dist/` are exactly what the build that just
+  ran emitted (other file types are out of scope; see
+  [Build Receipts](#build-receipts)), and that the compiled `DEBUG` state of the
+  bundles in it is the one that was asked for. Both arguments are required and
+  neither has a default: the expected mode is stated by the caller rather than
+  read from `AUTISTMASK_DEBUG`, and the file list 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, and read the `make build` and

TODO.md

@@ -26,7 +26,8 @@ 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/`, verified against the build's own receipt to
-be exactly what that build emitted with `DEBUG` compiled off.
+hold exactly the regular files and symlinks 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 +45,16 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-08-23: `README.md` and `script/verify-build`'s own comments now state the
+  emitted-tree guarantee at the width the code actually enforces
+  ([#331](https://git.eeqj.de/sneak/AutistMask/issues/331)). The tree walk is
+  `-type f -o -type l`, so the guarantee covers regular files and symlinks under
+  `dist/`; fifos, sockets, device nodes and empty directories are not checked,
+  because a build emits none of them, none can carry a shippable payload, and
+  grep on a fifo would hang rather than fail. The exclusion is deliberate and
+  unchanged — the README said "nothing under `dist/` that the build did not
+  write", which was broader than that. Documentation only; no executable line
+  changed.
 - 2026-08-20: A second extension page can no longer silently delete a wallet
   ([#304](https://git.eeqj.de/sneak/AutistMask/issues/304)). `saveState()` wrote
   the entire state blob, and every extension page — the toolbar popup, a dApp

script/verify-build

@@ -29,12 +29,16 @@
 # 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.
+# byte the output of the build.js run that just finished, with no regular file
+# or symlink added, missing or altered in between, and that the audited bundles
+# in it compiled to the requested mode. Regular files and symlinks are the whole
+# of what the tree walk covers; fifos, sockets, device nodes and empty
+# directories under dist/ are not checked, because a build emits none of them,
+# none can carry a shippable payload, and grep on a fifo would hang rather than
+# fail. 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
@@ -392,8 +396,10 @@ check_receipt_entries() {
 #     its own command line, so a linked dist/ collapses this walk to one entry
 #     and cross-checks nothing.
 #
-# 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.
+# Types other than regular files and symlinks — fifos, sockets, device nodes and
+# empty directories — are left out on purpose, and the guarantee is bounded to
+# what is walked: a build emits none of them, none can carry a shippable
+# payload, and grep on a fifo would hang rather than fail.
 check_dist_tree() {
     LISTING="$(mktemp "${TMPDIR:-/tmp}/verify-build-dist.XXXXXX")" ||
         fail "could not create a temporary file for the dist/ listing, so the