[BunsDev]

Val chose "Defer offscreen answers" on 2026-10-30 after the hosted cold-open analysis. This PR is for Val's review before it is queued.

Why. The approved 500 ms five-launch cold-open gate (e2e/transcript-measure.spec.ts) failed on hosted runner variance. Across 33 hosted runs on 2026-10-30 the median was 377.7 ms. Run 41056164788 failed at 781.9 ms on application code identical to a 436.1 ms pass two minutes earlier. Traces show a cold open is one renderer task of 150–180 ms (locally), about 110 ms of it parsing Markdown for every visible answer.

Change.

• DeferMarkdown (Markdown.tsx) wraps every turn before the newest eight (ThreadView.tsx). Its Markdown shows as written (escaped text, .md-deferred) until it comes within 1,500 px of the transcript's view, then parses once and stays parsed.
• Text already parsed this session renders at once.
• The newest turns and any streaming turn are unchanged.
• Chromium's scroll anchoring keeps the reader's place while answers above it parse.

The gate is unchanged. The budget probe now also requires the last answer to be parsed Markdown, so a deferred answer can't count as opened.

Results (local, M5 Max).

• Five-launch median: about 190 ms before, 88 ms after.
• With the first open throttled to 3× CPU: medians 806–870 ms before, 312–340 ms after.
• First-pass full suite:
  • build and unit tests passed;
  • E2E 477 passed, 7 skipped, 1 failed;
  • the failure was the Companion clipboard case companion.spec.ts:44, which is unrelated and passed when rerun alone.

Tests.

• New e2e/markdown-defer.spec.ts:
  • the newest answer parses at once, and the oldest parses on scroll and stays parsed;
  • a middle answer doesn't move while the answers above it parse. Negative control: with overflow-anchor: none this case fails, moving 96 px.
• New unit cases in test/markdown-render.test.ts.

For review.

• Until an answer nears the view, assistive technology would read it as Markdown source. VoiceOver moves the view as it navigates; no person has tested this, and C1–C5 remain deferred.
• Copying a deferred answer copies its Markdown source.

Evidence: docs/reviews/2026-10-30-deferred-markdown.md; status.md updated.

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
modex	Ready	Preview	Oct 31, 2026 3:59am UTC

[github-code-quality]

Code coverage overview

Languages: TypeScript

TypeScript / code-coverage-agent

main 21f6a70	hosted-budget ac107ab	+/-
66%	66%	0%

View coverage of the 2 most impacted files.

File	main 21f6a70	hosted-budget ac107ab	+/-
apps/desktop/sr...ts/Markdown.tsx	89%	87%	-2%
apps/desktop/sr...gine/plugins.ts	97%	97%	0%

ℹ️ Calculations represent line coverage. Results may change as calculations are updated.

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_{Updated October 31, 2026 05:06 UTC}