refactor(web): every textarea caps its growth; the diff comment box is a Textarea

[juliusmarminge]

Two review forms capped the auto-growing field at 16rem through a slot
selector; every auto-growing textarea should stop somewhere, so the cap
is in the base. The diff comment box rendered an unstyled Textarea and
rebuilt its whole look through nine slot-piercing utilities; it is now a
plain size="sm" Textarea.

Visible effect: the inline diff comment box gets the standard input
border, background and 14px text instead of a faint 50% border at 12px;
long comment fields everywhere stop growing at 16rem.

Lowers the no-restyle ceiling from 674 to 660.

Layer 17 of 24 in stack #13044, ordered least to most opinionated. Part of the components/ui className cleanup (audit and guardrail: #12982). Each layer lowers the shadcn/no-restyle ceiling; CI fails if the count rises. For every override cluster the question was "is this a real design-system concept, or should the primitive get stricter and the consumers change?"; a prop was only added for the former.

Written by Claude Fable 5 in Claude Code.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Improvements
  • Text areas now automatically grow as content is entered, up to a maximum height.
  • Longer text remains accessible through scrolling once the maximum height is reached.
  • Comment, review, and draft forms now provide more consistent text-area sizing and behavior across the interface.
  • Draft comment fields retain their standard compact control appearance while supporting the updated auto-growing behavior.

Before / after

Captured at 1280×800 from the same seeded data. "After" is the top of stack #13044, so these show the cumulative effect of every layer up to and including the last one; the relevant change for this PR is described above.

dialog-git

before (main)	after (top of stack)

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	13.5 KiB	—	15.1 KiB	✅
Codex	Thread snapshot wire	—	7.0 KiB	—	7.3 KiB	✅
Codex	Live turn WebSocket wire	—	6.5 KiB	—	7.8 KiB	✅
Codex	Live turn WebSocket decoded	—	56.3 KiB	—	66.4 KiB	✅
Codex	Live turn messages	—	10	—	21	✅
Claude	Total thread wire	—	13.5 KiB	—	15.1 KiB	✅
Claude	Thread snapshot wire	—	7.1 KiB	—	7.3 KiB	✅
Claude	Live turn WebSocket wire	—	6.4 KiB	—	7.8 KiB	✅
Claude	Live turn WebSocket decoded	—	57.0 KiB	—	66.4 KiB	✅
Claude	Live turn messages	—	9	—	21	✅

Baseline: unavailable · PR result: e95fa97 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 114.0 KiB
• Claude decoded thread snapshot: 114.7 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

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Review profile: CHILL

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Run ID: c94f73a4-ae03-4f6f-9ebc-ccb777cbb912

📥 Commits

Reviewing files that changed from the base of the PR and between 1183483 and e95fa97.

📒 Files selected for processing (6)

• apps/web/src/components/diffs/DiffCommentAnnotation.test.tsx
• apps/web/src/components/diffs/DiffCommentAnnotation.tsx
• apps/web/src/components/pullRequest/PullRequestCommentForm.tsx
• apps/web/src/components/pullRequest/PullRequestReviewForm.tsx
• apps/web/src/components/ui/textarea.tsx
• scripts/lint-restyle-ceiling.ts

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository: pingdotgg/t3code/.coderabbit.yaml

Review profile: CHILL

Plan: Team

Run ID: 3f377429-4a0f-43cf-b5de-a765191bd3c1

📥 Commits

Reviewing files that changed from the base of the PR and between f4517d1 and 1183483.

📒 Files selected for processing (1)

• apps/web/src/components/diffs/DiffCommentAnnotation.test.tsx

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📝 Walkthrough

Walkthrough

The shared Textarea now grows with content up to max-h-64, then scrolls. Component-specific styling overrides were removed. The restyle lint ceiling changed from 831 to 817.

Changes

Textarea auto-growth

Layer / File(s)	Summary
Shared Textarea height behavior apps/web/src/components/ui/textarea.tsx, apps/web/src/components/diffs/DiffCommentAnnotation.tsx, apps/web/src/components/pullRequest/PullRequestCommentForm.tsx, apps/web/src/components/pullRequest/PullRequestReviewForm.tsx, apps/web/src/components/diffs/DiffCommentAnnotation.test.tsx	The shared Textarea now uses max-h-64. Draft, comment, and review textareas no longer apply the removed styling overrides. The draft composer test checks the standard small textarea attributes.
Restyle lint ceiling scripts/lint-restyle-ceiling.ts	RESTYLE_CEILING changed from 831 to 817.

Priority: ⬇️ Low

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

Change: Refactor

Suggested reviewers: bil0000

Merge Risk: ⚪ Minimal · up to 11834

The changes are mergeable with no identified functional or operational risk.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
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 1 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies both primary changes: the textarea growth cap and the diff comment box conversion to the standard Textarea.
Description check	✅ Passed	The description explains what changed, why the changes were made, and includes UI before-and-after screenshots. It omits the template headings and checklist, but it provides the main required informat…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — The shared Textarea now changes growth and scrolling behavior for many existing customer-facing fields, and the diff-comment composer adopts the standard Textarea styling. This broad default UI change should be validated across the affected forms.

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