fix(core): preserve dynamic tool descriptions on session resume

[sehoon38]

Summary

Fixes a bug where dynamic tool descriptions (e.g., specific filenames or search queries) were lost and replaced by generic tool descriptions when resuming a session.

Details

Since the initial implementation of session recording (PR #6721), ChatRecordingService.recordToolCalls has been unconditionally overwriting incoming tool descriptions with generic ones from the ToolRegistry. Furthermore, GeminiChat.recordCompletedToolCalls was not extracting or providing the dynamic description from the tool invocation.

This PR:

1. Modifies ChatRecordingService.recordToolCalls to prioritize and preserve existing descriptions if provided.
2. Updates GeminiChat.recordCompletedToolCalls to extract the dynamic description using invocation.getDescription() (with a safe truthiness check) and pass it to the recording service.

Related Issues

Fixes #18842

How to Validate

1. Start a session: gemini
2. Run a command that uses tools with dynamic descriptions, e.g., Read GEMINI.md
3. Verify the UI shows "Read file GEMINI.md"
4. Exit the session.
5. Resume the session: gemini --resume latest
6. Verify the UI still shows "Read file GEMINI.md" instead of the generic "Reads and returns the content of a specified file."

[gemini-cli]

Hi @sehoon38, thank you so much for your contribution to Gemini CLI! We really appreciate the time and effort you've put into this.

We're making some updates to our contribution process to improve how we track and review changes. Please take a moment to review our recent discussion post: Improving Our Contribution Process & Introducing New Guidelines.

Key Update: Starting January 26, 2026, the Gemini CLI project will require all pull requests to be associated with an existing issue. Any pull requests not linked to an issue by that date will be automatically closed.

Thank you for your understanding and for being a part of our community!

[gemini-code-assist]

Summary of Changes

Hello @sehoon38, 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 addresses a regression where specific, dynamic descriptions of tool calls were lost when a chat session was resumed. The changes ensure that these detailed descriptions, which provide context like specific filenames or search queries, are correctly captured and retained across sessions, improving the user experience by maintaining conversational fidelity.

Highlights

• Dynamic Tool Description Preservation: Modified ChatRecordingService.recordToolCalls to prioritize existing dynamic tool descriptions, preventing them from being overwritten by generic ones upon session resume.
• Tool Invocation Description Capture: Updated GeminiChat.recordCompletedToolCalls to correctly extract and provide the dynamic description directly from the tool invocation.
• New Test Coverage: Added a new test case in chatRecordingService.test.ts to specifically validate that dynamic tool descriptions are preserved and not overwritten.

Changelog

• packages/core/src/core/geminiChat.ts
  • Added a new description field to the ToolCallRecord object, populating it dynamically from call.invocation.getDescription() or JSON.stringify(call.request.args).
• packages/core/src/services/chatRecordingService.test.ts
  • Introduced a new test case to verify that dynamic tool descriptions are preserved and not replaced by generic ones when recording tool calls.
• packages/core/src/services/chatRecordingService.ts
  • Adjusted the logic for assigning the description field in recordToolCalls to prioritize toolCall.description if it exists, falling back to toolInstance?.description otherwise.

Activity

• The pull request was created by sehoon38 to fix a regression reported by a user in a preview release.
• The author has provided detailed steps for validating the fix, including starting and resuming a session with dynamic tool usage.
• The pre-merge checklist indicates that tests have been added/updated and validation on MacOS (npm run) has been completed.

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[github-actions]

Size Change: +120 B (0%)

Total Size: 26.5 MB

ℹ️ View Unchanged

Filename	Size	Change
./bundle/gemini.js	26 MB	+120 B (0%)
./bundle/node_modules/@google/gemini-cli-devtools/dist/client/main.js	221 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/_client-assets.js	227 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/index.js	11.5 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/types.js	132 B	0 B
./bundle/sandbox-macos-permissive-open.sb	890 B	0 B
./bundle/sandbox-macos-permissive-proxied.sb	1.31 kB	0 B
./bundle/sandbox-macos-restrictive-open.sb	3.36 kB	0 B
./bundle/sandbox-macos-restrictive-proxied.sb	3.56 kB	0 B
./bundle/sandbox-macos-strict-open.sb	4.82 kB	0 B
./bundle/sandbox-macos-strict-proxied.sb	5.02 kB	0 B

_{compressed-size-action}

[gemini-code-assist]

Code Review

This pull request correctly addresses a regression where dynamic tool descriptions were lost on session resume. The changes ensure that the dynamic description from a tool invocation is captured and prioritized during chat recording. However, I've identified a potential critical issue that could lead to a runtime error due to an unsafe property check, and a high-severity issue regarding the handling of optional string fallbacks that deviates from repository guidelines. Please see my detailed comments for suggestions to improve the robustness of this fix.

[jacob314]