CI: enforce check-pr-image-urls.sh on PR bodies — relay media URLs ship as broken images

[baxen]

Problem

scripts/check-pr-image-urls.sh correctly rejects Buzz/relay /media/<sha>.png URLs in PR markdown, but nothing enforces it, so the guard only fires for someone who already knows to run it. The failure is silent and asymmetric: relay media requires auth, so the URLs render perfectly for the author (logged into Buzz) while GitHub's camo proxy fetches anonymously and gets 401 application/json — every reviewer sees a broken image.

Confirmed on a live URL:

$ curl -s -o /dev/null -w '%{http_code} %{content_type}\n' \
    https://buzz.block.builderlab.xyz/media/<64-hex>.png
401 application/json

Two PRs shipped this defect in the same week: #6720 (four broken images, since fixed) and #6536 (five, routed to its author). Both were reviewed and approved in Buzz, where the images resolve — so review does not catch it either.

Why the current guard misses

• Not referenced anywhere in .github/ — no CI job runs it.
• scripts/post-screenshots.sh runs it only when given the optional 3rd body-file arg (post-screenshots.sh:74). The common paths — gh pr edit --body, gh pr create --body, editing the body in the GitHub UI — are never checked.
• AGENTS.md:283 and desktop/src-tauri/src/managed_agents/screenshot_skill.md:19 both document it as a manual step.

buzz upload file is the natural reflex for anyone working inside a Buzz channel, which makes this an easy trap for both humans and agents.

Proposed fix

A CI check on the PR body itself, which is the only place that catches all authoring paths (including the web UI):

• Workflow on pull_request_target with types: [opened, edited], reading github.event.pull_request.body into a temp file and running scripts/check-pr-image-urls.sh on it. Should also scan PR comments on issue_comment, or at minimum the body.
• pull_request_target is needed to run the trusted base version of the script; it must not check out or execute PR-authored code.

A pre-push hook is not sufficient — the body is authored outside git and frequently edited after push.

Secondary hardening, cheap and worth doing regardless:

• Make the body-file arg to post-screenshots.sh the default path rather than optional.
• Have the checker also flag any https?:// image whose host is not an allowlisted GitHub-safe host, rather than pattern-matching only relay/sprout URLs — an unknown third-party host has the same camo failure mode.

Acceptance

• A PR whose body contains a relay /media/<sha>.(png|jpg|webp|gif) URL fails a required check, with the offending line and the post-screenshots.sh remedy in the failure output.
• Editing the body to fix it re-runs the check and passes.
• Verification is an anonymous fetch asserting 200 image/png — not a logged-in eyeball.

Found while fixing #6720; filed as a follow-up rather than changing that PR.

[baxen]

Same class, second instance: the file-size gate does not cover .mjs

Filing this here rather than as its own issue because it is the same failure shape as the image-URL guard: a check that does not cover its own subject, and passes silently on the thing it exists to catch.

Found on #6720. AgentSessionTranscriptList.conversation.test.mjs reached 1253 lines — over the repo's hard 1000-line ceiling documented at AGENTS.md:608 ("Hard ceiling: 1000 lines/file, enforced across Desktop, Web, and Mobile by the repository-level just file-size-check gate") — and just file-size-check, just check, the pre-push hook, and CI were all green. Codex caught it in review; no automated gate did.

Why it misses

desktop/scripts/check-file-sizes.mjs declares per-root rules with an explicit extension allowlist, and every TS/TSX root lists only .ts/.tsx:

{ root: "src/features", extensions: new Set([".ts", ".tsx"]), maxLines: MAX_LINES },

scripts/check-file-sizes-core.mjs then skips anything outside the allowlist:

if (!rule || !rule.extensions.has(path.extname(relativePath))) continue;

So .mjs is not "unenforced by accident of path" — it is filtered out by extension inside governed roots. Same in web/scripts/check-file-sizes.mjs. Desktop's test suite is *.test.mjs by convention (AGENTS.md desktop testing section), so the entire desktop test corpus is outside the ceiling — 545 .mjs files under the governed roots.

Current scale of the gap

At fd2e01799, files under already-governed roots that the extension filter excludes and that are over the ceiling:

lines	file
2452	desktop/src/features/agents/activeAgentTurnsStore.test.mjs
2236	desktop/src/features/community-members/useCommunityJoinAlerts.test.mjs
2079	desktop/src/features/agents/ui/agentSessionTranscript.test.mjs
1875	desktop/src/features/agents/ui/agentSessionTranscriptGrouping.test.mjs
1566	desktop/src/features/agents/ui/editAgentProviderDiscovery.test.mjs
1444	desktop/src/features/agents/ui/createAgentLocalModeGate.test.mjs
1438	desktop/src/shared/ui/markdown.test.mjs
1407	desktop/src/features/messages/lib/useDrafts.test.mjs
1357	desktop/src/shared/api/relayReconnectReplay.test.mjs
1189	desktop/src/features/agents/ingestArchivedObserverEvents.test.mjs
1131	desktop/src/features/terminal/terminalBannerWave.test.mjs
1037	desktop/src/features/terminal/TerminalSubstrate.test.mjs

12 files, up to 2.4× the ceiling.

Proposed fix

Add .mjs to the extension sets for the existing governed roots in desktop/scripts/check-file-sizes.mjs (and web/'s, for symmetry). No new roots, no new limit.

This is cheap because the gate is already a ratchet, not an absolute bound — allowedLineCount in check-file-sizes-core.mjs returns baseLines when the base file already exceeds maxLines:

export function allowedLineCount(baseLines, maxLines) {
  return baseLines == null || baseLines <= maxLines ? maxLines : baseLines;
}

So all 12 files above are grandfathered at their current size and simply may not grow, while any new .mjs file is held to 1000 from birth. That is exactly the discipline AGENTS.md:608 already claims to be enforcing. No mass split is required to turn it on.

Acceptance

• A new .mjs file over 1000 lines under a governed root fails just file-size-check.
• An existing over-limit .mjs file passes unchanged and fails on any growth.
• Add a case to scripts/check-file-sizes-core.test.mjs covering the extension allowlist for .mjs, so the coverage itself is asserted rather than assumed.

Also noted on #6720 (same "unenforced guard" family, separate fix)

ForumPostCard.tsx:91-95 has the identical avatar+adjacent-name shape that Carl flagged on the focus-mode identity row: UserAvatar exposes alt="<name> avatar" (or initials) immediately before the visible author label, so assistive tech announces the author twice. #6720 fixed it at its own call site with an aria-hidden wrapper rather than teaching the shared UserAvatar a decorative mode — UserAvatar has ~45 call sites and changing a shared component's accessible name was out of that PR's scope. Recording it here so the sibling is not lost; the general version is probably "an aria-hidden / decorative option on UserAvatar, applied at every site where a visible name is adjacent", which also has no gate today.

[baxen]

Fix is up as #6736 (ce1f1d427), off main, scoped to the file-size half only — the check-pr-image-urls.sh enforcement this issue opened with is untouched and still open.

Confirmed the ratchet behaves as described before pushing, against all twelve oversize files at once rather than reasoning from the source: rewriting each without changing its line count exits 0, adding one line to each exits 1 naming all twelve with their inherited limits. So the extension change needs no splits — each of the twelve is pinned where it stands and new .mjs files are held to 1000 from birth. Counts and the full evidence are in the PR body.