fix(web): allow full contrast in assistant replies

[maria-rcks]

Assistant paragraphs and expanded details stayed at 80% color alpha even at maximum appearance contrast. Their alpha now follows the existing contrast boost, reaching 100% at 200% contrast while preserving the default styling.

Fixes #11238.

Verified a real Codex reply through the web client in both themes: paragraphs, lists, and expanded details reach alpha 1 at 200%; all sampled colors at 100% and syntax highlighting at 200% remain unchanged. Details collapse/reopen works. Blacksmith scoped lint, web typecheck, and 52 existing contrast/Markdown tests passed. The desktop renderer shares this code; native desktop was not exercised.

Before, dark at 200%:

After, dark at 200%:

Before, light at 200%:

After, light at 200%:

Implemented with gpt-6-astra through Codex.

[macroscopeapp]

Approvability

Verdict: Approved at d081ce9

Macroscope's review found this PR approvable — This is a focused one-file styling fix that makes assistant markdown honor the existing contrast preference, while leaving default rendering unchanged. The runtime impact is limited to markdown text opacity and introduces no schema, infrastructure, security, billing, or static-analysis changes.

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[coderabbitai]

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ℹ️ Recent review info

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Run ID: 362ee6f6-afeb-4361-8609-7c2044710a84

📥 Commits

Reviewing files that changed from the base of the PR and between 7a2cce8 and d081ce9.

📒 Files selected for processing (1)

• apps/web/src/components/ChatMarkdown.tsx

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📝 Walkthrough

Walkthrough

ChatMarkdown now adjusts text alpha using --appearance-contrast-boost for both root content and expanded details content.

Changes

ChatMarkdown contrast styling

Layer / File(s)	Summary
Apply contrast-aware text alpha apps/web/src/components/ChatMarkdown.tsx	The root container and expanded details wrapper now calculate text alpha from --appearance-contrast-boost instead of using fixed 80% alpha.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to d081c

The contrast-aware text styling preserves default opacity and reaches full opacity at maximum configured contrast, with no active merge-blocking issue identified.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	For #11238, the implementation updates both the ChatMarkdown root and expanded-details wrapper. The formula keeps 80% alpha at default contrast and reaches 100% at 200% because `--appearance-contrast-…	Add automated coverage that checks computed color alpha at default and 200% contrast for paragraphs, list items, and expanded details. Run the coverage for light and dark themes. Include assertions for default styling, syntax highlighting, …
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: enabling full contrast in assistant replies.
Description check	✅ Passed	The description explains the contrast change, the issue it fixes, and the verification performed. It does not use the template headings, and the referenced before/after UI evidence and checklist are n…
Out of Scope Changes check	✅ Passed	The whole-PR diff changes only the two reply-text color declarations in apps/web/src/components/ChatMarkdown.tsx. Both declarations directly implement #11238 for ordinary reply content and expanded …

Full details: Linked Issues check

Explanation

For #11238, the implementation updates both the ChatMarkdown root and expanded-details wrapper. The formula keeps 80% alpha at default contrast and reaches 100% at 200% because --appearance-contrast-boost is 100% at that setting. List items inherit the root color. However, the whole-PR diff contains no automated test changes. The reviewed evidence does not verify computed color alpha, both light and dark themes, or preservation of syntax highlighting and secondary text roles.

Resolution

Add automated coverage that checks computed color alpha at default and 200% contrast for paragraphs, list items, and expanded details. Run the coverage for light and dark themes. Include assertions for default styling, syntax highlighting, and secondary UI text roles.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

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