Automate a review finding as a lint or test: Screenshots: the pull has no before/after of the open prompt in light and dark ( #12364

The gate now refuses a pull that changes src/web/ (.ts or .css) without saying which page's before/after pictures show the change. The new test passes, as does the existing both-doors gate test. bun scripts/gate.ts and bun x tsc --noEmit both came back clean.

What changed

• Rule: a commit message must carry Looks: <path>, where the path is a page in app.looks in forge.json. The forge already takes light and dark pictures of those pages on every pull's preview. The alternative is No look: <why>, with a reason of 10+ characters.
• Failure message: it names the rule, rule "before/after looks", plus the changed files, and says to name an app.looks page or give a No look: reason. A Looks: path that isn't in app.looks gets its own message.
• Code: src/kernel/look_rule.ts holds the rule, wired into scripts/gate.ts as lookRefusal next to the both-doors and try-it rules. AGENTS.md has a one-line note. test/look-rule.test.ts covers refusal, a valid path, an unknown path, the waiver, short reasons, .css, and deletions, tests and other files being exempt.

What I left out

• The check can't read the pull description, so it cannot verify that screenshots are actually pasted there. It checks that the pull names a pictured page; the forge's own previews supply the pictures.
• It does not check that the named page really renders the changed component, or that light and dark are both taken.

How to try it Change a file under src/web/, commit without a Looks: line, and run bun scripts/gate.ts. It exits 2 with the rule's message. Add Looks: /flow to a commit message and it passes.

Closes #12362

The gate now refuses a pull that changes src/web/ (.ts or .css) without saying which page's before/after pictures show the change. The new test passes, as does the existing both-doors gate test. bun scripts/gate.ts and bun x tsc --noEmit both came back clean.

What changed

• Rule: a commit message must carry Looks: <path>, where the path is a page in app.looks in forge.json. The forge already takes light and dark pictures of those pages on every pull's preview. The alternative is No look: <why>, with a reason of 10+ characters.
• Failure message: it names the rule, rule "before/after looks", plus the changed files, and says to name an app.looks page or give a No look: reason. A Looks: path that isn't in app.looks gets its own message.
• Code: src/kernel/look_rule.ts holds the rule, wired into scripts/gate.ts as lookRefusal next to the both-doors and try-it rules. AGENTS.md has a one-line note. test/look-rule.test.ts covers refusal, a valid path, an unknown path, the waiver, short reasons, .css, and deletions, tests and other files being exempt.

What I left out

• The check can't read the pull description, so it cannot verify that screenshots are actually pasted there. It checks that the pull names a pictured page; the forge's own previews supply the pictures.
• It does not check that the named page really renders the changed component, or that light and dark are both taken.

How to try it Change a file under src/web/, commit without a Looks: line, and run bun scripts/gate.ts. It exits 2 with the rule's message. Add Looks: /flow to a commit message and it passes.

I merged main into this branch and pushed it. The merge had one conflict, in scripts/gate.ts. The check list there now runs both lookRefusal (from this pull) and dependencyRefusal (from main).

• Gate fix: after the merge, bun scripts/gate.ts flagged one line of src/kernel/look_rule.ts as over 100 columns. I rewrapped that comment, and the gate now passes.
• Tests: bun x tsc --noEmit is clean. I ran the 13 test files covering the look rule, the review rules and the gate; all 72 tests pass. I did not run the full suite: the changed-file helper (scripts/fast.ts) reported the diff as too broad to name tests, so I picked the covering tests myself. The forge's check runs the full suite on this push.