fix(studio): Flashing on chat components when Code Agents is thinking

[htolentino-nvidia]

Summary by CodeRabbit

• Bug Fixes
  • Improved chat run handling so cancelled or interrupted requests exit more cleanly and avoid inconsistent “running” states.
  • Error messages are now surfaced more consistently when a chat action fails.
• Refactor / Maintenance
  • Streamlined chat thread rendering by reusing shared UI settings (no intended behavior change).
  • Improved internal runtime performance by keeping key handlers stable across renders.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: e34ca78a-16f1-4024-b369-395bcabdd56c

📥 Commits

Reviewing files that changed from the base of the PR and between 1a59825 and 409a274.

📒 Files selected for processing (4)

• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/ClaudeCodeChatThread.tsx
• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/context/ClaudeCodeChatProvider.tsx
• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/useClaudeCodeChatRuntime.ts
• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/useCustomAssistantChatRuntime.ts

✅ Files skipped from review due to trivial changes (2)

• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/ClaudeCodeChatThread.tsx
• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/context/ClaudeCodeChatProvider.tsx

🚧 Files skipped from review as they are similar to previous changes (2)

• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/useClaudeCodeChatRuntime.ts
• web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/useCustomAssistantChatRuntime.ts

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📝 Walkthrough

Walkthrough

Claude Code chat thread props are extracted into shared constants. The provider and runtime use memoized error/run callbacks and typed runtime handlers. The assistant run flow now delays message creation until after pre-run checks and no longer finalizes cancelled runs.

Changes

Claude Code chat route updates

Layer / File(s)	Summary
Thread props constants web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/ClaudeCodeChatThread.tsx	AssistantChatThread now reads message-content props and empty-state text from module-level constants.
Provider error handler web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/context/ClaudeCodeChatProvider.tsx	The provider memoizes toast error handling and passes the callback into the Claude Code chat runtime.
Memoized runtime callbacks web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/useClaudeCodeChatRuntime.ts	The runtime hook imports run-context types, memoizes handleRun, uses the workspace variable in streaming, and wires onRun: handleRun into the custom assistant runtime.
Run initialization timing web/packages/studio/src/routes/agents/ClaudeCodeChatRoute/useCustomAssistantChatRuntime.ts	runCompletion now skips assistant-message creation on early cancel, abort, or stale-run checks, and cancelled runs no longer finalize with CANCELLED_STATUS.

Possibly related PRs

• NVIDIA-NeMo/nemo-platform#435: Same ClaudeCodeChatRoute runCompletion and onBeforeRun flow.
• NVIDIA-NeMo/nemo-platform#153: Same Claude Code runtime wiring and run-context hook changes.
• NVIDIA-NeMo/nemo-platform#236: Same chat route message rendering and studio-link path.

Suggested reviewers

• dmariali
• steramae-nvidia

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title matches the PR’s main goal: reducing chat component flashing while Code Agents is thinking.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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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✨ Finishing Touches

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• Create stacked PR
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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch studio-code-agent-fix-flashing/htolentino

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[github-actions]

Suite	Lines Covered	Line Rate	Branch Rate
Unit Tests	20910/27478	76.1%	61.2%
Integration Tests	12108/26247	46.1%	19.5%