fix(capture): ignore terminal EventSource 204 aborts

[BenSheridanEdwards]

Why does this feature exist?

Chromium can emit a successful HTTP 204 response followed by requestfailed(net::ERR_ABORTED) when an EventSource is intentionally told not to reconnect. StyleProof treated the later browser event as failed data residue, so a clean capture could be blocked despite the stream reaching its protocol-defined terminal state.

What changed?

• Track residue observations by Playwright request identity until readout.
• Treat only an EventSource HTTP 204 as terminal, clearing a failure observation for that same request regardless of browser event order.
• Keep fail-closed behavior for aborts without a terminal response, interrupted HTTP 200 streams, non-EventSource HTTP 204 responses, and all HTTP 4xx/5xx responses.
• Add deterministic unit coverage, a real Chromium regression test, reviewer-facing proof, and a changelog entry.
• No dependency, configuration, baseline format, or public API changes.

Behavioural Proof (with video and screenshots)

• Video: Not applicable — this changes browser network-event classification and has no motion or interactive UI behavior.

• Screenshots:

  

• Behaviour tests:

  Red before the implementation:

  not ok 4 - an EventSource HTTP 204 terminal response is clean when Chromium later reports ERR_ABORTED
  expected: []
  actual:   [{ key: 'dashboard·/api/stream', reason: 'net::ERR_ABORTED' }]
  

  Green after the implementation:

  node --test test/data-residue.test.mjs
  tests 13
  pass 13
  fail 0
  
  npx playwright test test/data-residue.e2e.spec.ts
  4 passed
  
  npx playwright test test/data-residue.e2e.spec.ts --grep 'EventSource terminal HTTP 204' --repeat-each=100
  100 passed
  

Verification Summary

• Definition of Done: followed .agents/project/DEFINITION_OF_DONE.md.
• Commands run:
  • npm run build && npm run typecheck && npm run lint && npm run format:check
  • npm run privacy:check
  • npm test
  • npm run test:e2e
  • npm run demo:report && npm run demo:check
  • npm audit --audit-level=high
  • npm pack --dry-run --json
  • focused Chromium regression repeated 100 times
• Results: all passed; 675 unit tests, 122 full browser tests, 100/100 focused Chromium repetitions, zero high-severity audit findings, and a clean package dry run.
• Known risks or skipped checks: the exception is deliberately narrow to EventSource HTTP 204 on the same Playwright request. Actual stream failures remain fail-closed. No checks were skipped.

Checklist

• Proof above — linked the regenerated docs/demo/report.md, or pasted the command/test output that demonstrates the change
• If you changed capture/diff/report rendering, ran npm run demo:report and committed docs/demo/
• npm run build && npm run typecheck && npm run lint && npm run format:check pass
• npm test passes (and npm run test:e2e if the capture/engine path changed)
• Added/updated tests for the change
• Updated the README / CHANGELOG if behaviour or the public API changed
• If captured output changed, noted that adopters must regenerate baselines — captured output and baseline format are unchanged
• Followed .agents/project/DEFINITION_OF_DONE.md and .agents/skills/pr-inline-screenshot-proof/SKILL.md
• Screenshots are committed and embedded inline with ![alt](...png?raw=1), or the proof section says Not applicable with the technical reason
• The PR body has no bare screenshot links, local paths, relative paths, or proof placeholders

[github-actions]

Note

Synthetic action dogfood receipt. This report is the final deliberately failing fixture in the action contract suite. It proves that unproven evidence is rejected; it does not certify this pull request.

🗺️ StyleProof report

📊 View the side-by-side visual report →

---

Coverage, determinism, or report/diff consistency evidence is incomplete — repair the capture or reflow source; reviewer approval cannot clear this failure.