fix(extension): reattach the write_cookies doc block, and name the writable cookies as writable

[chrischall]

Closes #212 — the two round-4 findings on #211, which merged before they could be addressed on that PR.

Orphaned doc block

partialWriteError was spliced in between handleWriteCookiesRequest's doc block and the function, so ~40 lines documenting the verb's four gates, its all-or-nothing refusal and the cookie-shadowing trap ended up describing a five-line string helper. The helper moves above the block; nothing else changes.

Worth naming the cause: I was editing source by matching a string anchor. The anchor matched, the edit applied, the build passed, the tests passed — and the result was still wrong, because nothing verifies that prose sits on the function it describes.

Cookie names headed "Read cookies" while granting a write

popup.ts listed cookieKeys under 'Read cookies' unconditionally. That sub-list is the only place those names appear, so a user granting write_cookies saw the affected cookies filed under a read verb — directly contradicting the capability line above it, which says "Overwrite cookies it can already read (can change your signed-in session)".

It now reads "Read and overwrite cookies" when the capability is present. The user sees one consistent story at the moment they decide, which is the whole point of itemising the names in the first place.

Pinned by a rendering test — renderPopup into a container, then read the actual <dt> — not a source-text match. The earlier popup test in this series asserted on source text and would have passed on a comment containing the right words; not worth repeating that mistake two PRs later.

Verified the test fails against the unfixed heading before fixing it.

Note on #212

I reopened it. Closes #212 went into #211's body when only the round-3 items were resolved, and round 4 then added these two to the same issue — so the merge closed it with both outstanding. Closes belongs on a PR only once every item is genuinely done, and I added it a round early.

1194 tests pass.

🤖 Generated with Claude Code

https://claude.ai/code/session_012o2nXwu7tov6j7ciBEpigo

[claude]

Claude finished @chrischall's task in 3m 1s —— View job

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Review complete

• Read CLAUDE.md for conventions
• Read PR diff
• Review background.ts changes
• Review popup.ts changes
• Review popup.test.ts changes
• Post findings

Summary

Both fixes described in the PR body check out:

• Orphaned doc block — git diff origin/main...HEAD -- packages/extension-core/src/background.ts confirms partialWriteError (background.ts:1858-1870) now sits entirely above the handleWriteCookiesRequest doc block, which is contiguous with the function it describes (background.ts:1872-1906). No logic changed, pure reordering.
• Cookie heading contradiction — popup.ts:699-703 now heads the cookie sub-list "Read and overwrite cookies" when write_cookies is granted, matching the capability line's "Overwrite …" wording. popup.test.ts:1011-1055 pins this with a real renderPopup + <dt> read (not a source-text match), and per the PR body the author verified it fails against the unfixed heading.

🟡 Nit

• popup.ts:701 — pending.capabilities.includes('write_cookies') dereferences pending.capabilities directly, while the same function computes a defensively-guarded caps local 8 lines earlier (popup.ts:672-674) precisely because pending.capabilities can be falsy for non-bootstrap callers ("Defensive: callers in test code may omit capabilities"). The one real production caller (popup.ts:931) always normalises to ['fetch'] at worst, so this isn't a live production bug today, but it's inconsistent with the established defensive pattern in the same function and would throw (blanking the whole popup) if a future/test caller omits the field. Swapping in caps.includes('write_cookies') matches the existing convention at no cost. Left as an inline comment with a fix link.

No other issues found — write_cookies handling, gate ordering, and the rest of the diff are unaffected.

Verdict: warn

[claude]

🟡 Nit: this dereferences pending.capabilities directly, but the caps local computed 8 lines above (packages/extension-core/src/popup/popup.ts:672-674) exists specifically because this same function treats pending.capabilities as possibly falsy:

// Defensive: callers in test code may omit `capabilities`, in which case we fall back to ['fetch'].
const caps = pending.capabilities && pending.capabilities.length > 0
  ? pending.capabilities
  : ['fetch'];

In the real bootstrap path this is safe today — the only production caller of renderPopup('pending-pair', …) normalises with capabilities: [...(pending.capabilities ?? ['fetch'])] (packages/extension-core/src/popup/popup.ts:931), so pending.capabilities can't actually be undefined there. But per the adjacent comment, non-bootstrap callers (test code, and any future caller) aren't guaranteed to supply it, and .includes on undefined would throw and blank the whole popup rather than just mis-labelling the cookie heading. Swapping in the already-computed caps.includes('write_cookies') would match the established defensive pattern in this same function at no cost.

Fix this →

[github-actions]

🟡 Auto-review verdict: warn — Both claimed fixes (doc-block reattachment, cookie-heading wording) check out against the diff and are covered by a genuine rendering test. One minor robustness nit found and posted inline.
📋 Tracking follow-ups: #216