fix(extension): use the guarded caps local for the cookie heading

[chrischall]

Closes #216.

It's a crash, not a consistency nit

caps is the defensively-guarded form — it falls back to ['fetch'] because callers may omit capabilities. My cookie heading read pending.capabilities directly, so an omitted field throws:

TypeError: Cannot read properties of undefined (reading 'includes')

That throw is inside renderPopup, so the pair popup renders nothing. The one UI a user depends on to see what they're approving fails closed into a blank panel — a worse outcome than the wrong heading that line was added to fix.

Filed as "inconsistent with the established defensive pattern", which is accurate but undersells it. Verified with a test before fixing: renders a pending-pair state with capabilities omitted, asserts no throw, and asserts the names still appear under "Read cookies" — the fallback is ['fetch'], which grants no cookie access at all, so the read heading is correct in that state.

The pattern in these three findings

All three review rounds since write_cookies merged found the same class of mistake: code that was right for the case I had in mind and wrong for the case the surrounding code had already handled. The guard was six lines above the line I added. So was the doc block I displaced, and the sibling pending* maps before that.

The correction isn't "be more careful" — it's to read the enclosing function for existing conventions before adding a call, rather than after a reviewer points at one.

1195 tests pass.

🤖 Generated with Claude Code

https://claude.ai/code/session_012o2nXwu7tov6j7ciBEpigo

[claude]

Claude finished @chrischall's task in 39s —— View job

---

PR Review: fix(extension): use the guarded caps local for the cookie heading

Status: ✅ Complete

---

Summary

This PR fixes a critical crash in the pair-approval popup. The bug occurs when an MCP omits the capabilities field—code at line 701 (now 705) directly accessed pending.capabilities.includes(), throwing TypeError: Cannot read properties of undefined inside renderPopup, which rendered the popup completely blank. This is worse than a wrong label because users can't see what they're approving.

The fix correctly switches to the defensively-guarded caps variable, which exists on line 672 for precisely this scenario and falls back to ['fetch'].

Findings

✅ No issues found.

The change is minimal, correct, and well-aligned with project conventions:

1. Correctness: The fix uses caps (the guarded form) instead of pending.capabilities (unguarded). The caps variable was already introduced on lines 672–674 for exactly this defensive pattern, and the code already uses caps on line 678 for the capability list rendering. This reintroduces consistency.

2. Documentation: The established defensive pattern is documented on lines 668–674 with clear comments explaining why callers may omit capabilities and why the fallback to ['fetch'] is necessary. The new comment (lines 701–704) explains the specific reason this code path must use caps: a throw inside renderPopup renders nothing at all.

3. Test coverage: The new test 'falls back rather than throwing when capabilities is omitted' (lines 1067–1091) directly validates the bug scenario:

   • Creates a pending object with no capabilities field
   • Asserts renderPopup() does not throw
   • Verifies the cookie keys still render under "Read cookies" (correct, since fallback is ['fetch'], which grants no cookie access)

4. Severity is reflected: The PR description correctly characterizes this as a crash, not just an inconsistency—the popup renders nothing when capabilities are omitted, a worse outcome than a wrong heading.

---

Verdict: pass
| PR branch

[github-actions]

✅ Auto-review verdict: pass — The PR correctly fixes a critical crash in the pair-approval popup by using the defensively-guarded caps variable instead of directly accessing pending.capabilities. The fix is minimal, properly tested, and aligns with established defensive coding patterns.