fix(devtools): reduce memory usage and defer connection

[SandyTao520]

Summary

Reduce DevTools memory footprint by lowering the network log buffer from 2000 to 10 entries, and stop eagerly connecting to existing DevTools servers on startup — transport is now only attached when the user presses F12.

Details

Two changes:

1. packages/devtools/src/index.ts: Network log cap reduced from 2000 → 10. Each log can hold a full LLM response body (tens to hundreds of KB), so 2000 entries was a significant memory sink. Console logs (5000 cap) are kept as-is since they are small.

2. packages/cli/src/utils/devtoolsService.ts: Removed the eager probeDevTools + addNetworkTransport call from setupInitialActivityLogger. Previously, every new CLI session would auto-detect and connect to an existing DevTools server at startup, sending data even if the user never opened DevTools. Now the logger starts in pure buffer mode (10 request groups), and only connects when F12 is explicitly pressed. The promotion/reconnect logic after F12 is unchanged.

Related Issues

Related to #18494

How to Validate

1. Start a CLI session without pressing F12 — verify no WebSocket connection to :25417
2. Press F12 — DevTools should start/connect normally, buffered logs flush to the UI
3. With DevTools open, make >10 API requests — older entries should be evicted from the network panel
4. Monitor memory usage over a long session — should be significantly lower than before

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:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[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 optimizes the DevTools memory footprint by limiting the number of stored network logs and preventing unnecessary background connections. By deferring the network transport initialization until requested, the CLI avoids overhead during sessions where DevTools is not utilized.

Highlights

• Memory Optimization: Reduced the network log buffer capacity from 2000 to 10 entries to significantly lower memory consumption.
• Lazy Connection: Removed eager DevTools server probing at startup; the transport connection is now deferred until the user explicitly triggers it via F12.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-cli]

Hi @SandyTao520, 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]

Code Review

This pull request refactors the activity logger initialization in the CLI to be synchronous and removes the eager probing for DevTools servers at startup, deferring transport attachment until triggered by the user. Additionally, it significantly reduces the maximum log history size in the DevTools package from 2000 to 10 entries. I have no feedback to provide.

[github-actions]

Size Change: -620 B (0%)

Total Size: 34.6 MB

Filename	Size	Change
./bundle/chunk-56CJ5T6Q.js	0 B	-14.8 MB (removed)	🏆
./bundle/chunk-7Y4CZ653.js	0 B	-3.82 MB (removed)	🏆
./bundle/core-ANDEH3WH.js	0 B	-45 kB (removed)	🏆
./bundle/devtoolsService-O6HYA7RE.js	0 B	-28.4 kB (removed)	🏆
./bundle/interactiveCli-6OV3X27R.js	0 B	-1.66 MB (removed)	🏆
./bundle/oauth2-provider-JN7UWWMV.js	0 B	-9.16 kB (removed)	🏆
./bundle/chunk-5WGO4JYJ.js	3.82 MB	+3.82 MB (new file)	🆕
./bundle/chunk-WJRNV7IN.js	14.8 MB	+14.8 MB (new file)	🆕
./bundle/core-DLPYAJJU.js	45 kB	+45 kB (new file)	🆕
./bundle/devtoolsService-MEX5GDIW.js	27.8 kB	+27.8 kB (new file)	🆕
./bundle/interactiveCli-2SQVKIDX.js	1.66 MB	+1.66 MB (new file)	🆕
./bundle/oauth2-provider-L7UQERPI.js	9.16 kB	+9.16 kB (new file)	🆕

ℹ️ View Unchanged

Filename	Size	Change
./bundle/bundled/third_party/index.js	8 MB	0 B
./bundle/chunk-34MYV7JD.js	2.45 kB	0 B
./bundle/chunk-5AUYMPVF.js	858 B	0 B
./bundle/chunk-664ZODQF.js	124 kB	0 B
./bundle/chunk-DAHVX5MI.js	206 kB	0 B
./bundle/chunk-IUUIT4SU.js	56.5 kB	0 B
./bundle/chunk-OBAOCC3L.js	1.96 MB	0 B
./bundle/chunk-RJTRUG2J.js	39.8 kB	0 B
./bundle/chunk-U4FACSVX.js	1.13 kB	0 B
./bundle/devtools-36NN55EP.js	696 kB	0 B
./bundle/dist-T73EYRDX.js	356 B	0 B
./bundle/events-CLX3JQHP.js	418 B	0 B
./bundle/gemini.js	533 kB	-12 B (0%)
./bundle/getMachineId-bsd-TXG52NKR.js	1.55 kB	0 B
./bundle/getMachineId-darwin-7OE4DDZ6.js	1.55 kB	0 B
./bundle/getMachineId-linux-SHIFKOOX.js	1.34 kB	0 B
./bundle/getMachineId-unsupported-5U5DOEYY.js	1.06 kB	0 B
./bundle/getMachineId-win-6KLLGOI4.js	1.72 kB	0 B
./bundle/memoryDiscovery-5MNMPINW.js	980 B	0 B
./bundle/multipart-parser-KPBZEGQU.js	11.7 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/client/main.js	222 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/_client-assets.js	229 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/index.js	13.4 kB	-2 B (-0.01%)
./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
./bundle/src-QVCVGIUX.js	47 kB	0 B
./bundle/tree-sitter-7U6MW5PS.js	274 kB	0 B
./bundle/tree-sitter-bash-34ZGLXVX.js	1.84 MB	0 B

_{compressed-size-action}