[avoidwork]

Description

Fixes issue #1454: a message bubble's streaming status is not cleared when a new message segment arrives after it. A pending AI message interrupted by a system message still shows a spinner erroneously. This change ensures the streaming flag on a prior assistant bubble is cleared when a subsequent message segment arrives, and adds a defensive spinner guard in MessageBubble rendering.

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactor (no functional changes)
• Performance improvement
• CI / build / tooling

Testing

• npm run test: 4206 tests pass, 0 fail.
• npm run lint: 0 warnings, 0 errors.
• npm run coverage: 91.48% overall line coverage maintained.
• Added regression tests in tests/unit/tui/messageList.test.js (addMessage clears stale streaming on a prior assistant message) and tests/unit/tui/messageBubble.test.js (no spinner when a bubble has content/segments despite a stale streaming: true).

Coverage

• Line coverage maintained

Checklist

• npm run lint passes
• Tests pass with maintained line coverage
• No forbidden patterns used
• Conventional Commit style applied

Closes #1454

[avoidwork]

Audit Results — fix-message-bubble-streaming-status (Implementation Audit)

Goal Fulfillment

• Goal 1 (clear stale streaming on prior assistant bubble when new segment arrives): Implemented in src/tui/messageList.js addMessage. When a new message segment is added, any prior assistant message with streaming: true is cleared to false and the bubble is notified via pub/sub.
• Goal 2 (defensive spinner guard): Implemented in src/tui/messageBubble.js. The pendingState computation is documented as a defensive guard — a bubble with content or segments never renders a spinner, even with a stale streaming: true.
• Goal 3 (regression tests): Added tests in tests/unit/tui/messageList.test.js (addMessage clears stale streaming) and tests/unit/tui/messageBubble.test.js (no spinner when content/segments present despite stale streaming).

Spec Compliance

• component-message-bubbles MODIFIED requirement: The MessageBubble streaming-status lifecycle clears the streaming flag when a new message segment arrives. ✓
• tui-streaming MODIFIED requirement: Every path ending an assistant stream clears the streaming flag. The addMessage clearing covers the "subsequent message segment" path; finalizeStreaming and handleInterrupt already cover the normal and interrupt paths. ✓

Task Completion

• All 8 tasks in tasks.md marked [x]. Verified via openspec instructions apply → state: all_done.

Quality Check

• Tests: 4206 pass (npm run test).
• Lint: 0 warnings, 0 errors (npm run lint).
• Coverage: 91.48% overall, maintained. messageBubble.js 93.61%, messageList.js 78.84%.
• npm start: Fails only due to Ink raw mode requiring a TTY (non-interactive sandbox limitation). Both changed modules import cleanly, confirming no code-level startup defect.

Decision

• Structured decision: 0.99 (≥ 0.6 → true, no errors). Implementation satisfies every goal, is spec-compliant, tasks complete, no obvious issues.