refactor(cli): centralize dense payload detection in tool mapping

[Arjan-P]

Title: refactor(ui): centralize dense payload detection in tool mapping

Summary

Refactors the UI to reduce its awareness of backend data internals. It moves the complex payload density
detection logic from ToolGroupMessage into mapToDisplay by introducing a hasDensePayload boolean
property to the IndividualToolCallDisplay interface.

Details

Previously, UI components (ToolGroupMessage.tsx) contained brittle type guards (isFileDiff) and object
shape checks to determine if a tool output was "dense" (e.g., a diff or structured object). This logic is
now centralized in mapToDisplay, making the UI component lighter and easier to maintain.

Related Issues

#28260

How to Validate

Run the targeted UI tests to ensure no regressions in component rendering:

npm test -w @google/gemini-cli-cli -- src/ui/components/messages/ToolGroupMessage.test.tsx
npm test -w @google/gemini-cli-cli -- src/ui/components/messages/ToolGroupMessage.compact.test.tsx
npm test -w @google/gemini-cli-cli -- src/ui/components/messages/ToolGroupMessageRegression.test.tsx

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods (Please confirm validation status)

[github-actions]

📊 PR Size: size/S

• Lines changed: 39
• Additions: +14
• Deletions: -25
• Files changed: 3

[Arjan-P]

/gemini review

[gemini-code-assist]

Code Review

This pull request refactors the determination of whether a tool call has a dense payload. The hasDensePayload calculation has been moved from the ToolGroupMessage UI component to the mapToDisplay hook in toolMapping.ts, and the result is now exposed as an optional boolean property on the IndividualToolCallDisplay interface. This successfully decouples the UI component from core internals like isFileDiff. I have no additional feedback to provide as the changes are clean and well-structured.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refactors the UI layer to decouple it from backend data internals. By centralizing the logic for detecting 'dense' tool payloads within the mapToDisplay function and exposing this state via the IndividualToolCallDisplay interface, the codebase becomes more maintainable and less prone to UI-specific regressions when data structures evolve.

Highlights

• Centralized Logic: Moved the dense payload detection logic from the UI component into the mapping layer, reducing UI component complexity.
• Interface Update: Added a new hasDensePayload boolean property to the IndividualToolCallDisplay interface to standardize payload identification.
• Refactored Component: Simplified ToolGroupMessage by removing brittle type guards and direct dependency on isFileDiff.

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[gemini-code-assist]

Code Review

This pull request refactors the dense payload detection logic for tool calls. The hasDensePayload helper function and its import of isFileDiff have been removed from the ToolGroupMessage component. This logic is now handled during the mapping phase in toolMapping.ts, which computes and assigns the hasDensePayload boolean property directly to the IndividualToolCallDisplay objects. There are no review comments, and I have no feedback to provide.