## Verdict
VERDICT: SHIP - all three round-3 findings are CLOSED at their cited lines, and the changed block introduces no new regression.

## Round-3 fix verification

- **Finding 1 (CRITICAL - row keydown swallows child activation): CLOSED.** The row carries no keydown listener, no `role`, no `tabIndex` - it is a plain container with only the mouse `click` at `popup.ts:329`. With no ancestor keydown in the tree, Space on the checkbox (`popup.ts:249-269`) toggles natively and Enter/Space on Open/Copy fire their own `click` handlers with `stopPropagation` intact. The failure path (keystroke on a child cancelled and replaced by switch) is structurally impossible now.
- **Finding 2 (MAJOR - keydown bypasses the busy lock): CLOSED.** The keydown's first statement is `if (deleting) { return; }` (`popup.ts:339-341`), mirroring `panel.ts:1371`, with the comment at `popup.ts:338` naming exactly why - the `jp-mod-busy` pointer-events scrim does not block keyboard. Mid-delete Enter/Space can no longer mutate the in-flight `selected` set or dispose the dialog.
- **Finding 3 (MAJOR - nested interactive inside `role="button"`): CLOSED.** `role="button"` and `tabIndex = 0` now sit on the label span (`popup.ts:335-336`), whose only descendants are the ellipsising text span (`popup.ts:286-289`) and a presentational badge span (`popup.ts:290-301`) - zero interactive children, so no axe `nested-interactive` and no name-concatenation of operable controls. This is the exact remedy round 3 prescribed.

## New-regression inspection of the changed block (popup.ts ~280-347)

All clean; the checks that mattered:

- **No double activation** - the label has no click listener; a mouse click on the label bubbles to the row's single `click` at `popup.ts:329`, and `role="button"` on a span does not synthesize click from keydown, so Enter fires `activate()` exactly once via `popup.ts:345`. Pass.
- **Scroll suppression** - `preventDefault()` at `popup.ts:344` before `activate()` keeps Space from scrolling the list. Pass.
- **Focus visibility** - no CSS rule targets `.jp-AiAssistantsPanel-branchLabel` on focus (`style/base.css:666-672`), and the label itself has no `overflow: hidden` (only the inner `branchLabelText` at `base.css:674-680` clips), so the default UA focus-visible ring renders unclipped. The fix's "no CSS change needed" claim holds. Pass.
- **Keyboard/mouse parity in selection mode** - Enter on the label runs the same `activate()` (`popup.ts:312-328`) as a row click: toggles selection while anything is ticked (with `check.checked` resynced at 321), switches only when nothing is selected. The keyboard route and the mouse route cannot diverge. Pass.
- **Tab order** - checkbox → label → Open → Copy follows DOM append order (`popup.ts:278, 302, 309-310`), matching the visual left-to-right layout. Pass.
- **No target guard needed** - the round-3 CRITICAL's `e.target !== row` guard is obsolete by construction: the new host has no interactive descendants whose keys could bubble into the handler. Correctly omitted rather than cargo-culted. Pass.

## What works

- The fix took the structural remedy (relocate the affordance) rather than patching symptoms (target guards on a wrong-shaped composite) - the CRITICAL and the ARIA violation died from one move
- The comment at `popup.ts:330-334` records *why* the affordance lives on the label and not the row, so the next engineer will not "simplify" it back into the regression
- The `deleting` guard carries its rationale inline (`popup.ts:338`), consistent with the existing busy-lock comment discipline this file already had

Per the pinned scope: no fresh sweep was run, nothing previously CLOSED or ruled was re-examined. Two consecutive clean states on this block - round 3's remedy applied verbatim, round 4 confirming it - this is done.
