docs: fix inconsistent commandRegex example in policy engine

[NTaylorMullen]

Summary

Fix inconsistent commandRegex documentation and example. The example incorrectly used a ^ anchor which would never match because the pattern is tested against stringified JSON arguments.

Details

• Updated docs/core/policy-engine.md to remove ^ from the commandRegex example.
• Added a note explaining that commandRegex prepends \"command\":\" to the pattern.
• Added a regression test in packages/core/src/policy/toml-loader.test.ts to verify that ^ in commandRegex causes a mismatch.

Related Issues

Fixes https://chat.google.com/room/AAQApBm33UQ/zJmZJPS5j1s/zJmZJPS5j1s?cls=10

How to Validate

1. Run the new test: npm test -w @google/gemini-cli-core -- src/policy/toml-loader.test.ts
2. Verify the test should NOT match if ^ is used in commandRegex because it matches against full JSON passes.
3. Review the updated docs/core/policy-engine.md.

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 @NTaylorMullen, 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 an inconsistency in the policy engine's commandRegex documentation and behavior. It clarifies how commandRegex patterns are evaluated against stringified JSON arguments, specifically highlighting why the ^ anchor can lead to unexpected mismatches. The changes improve the accuracy of the documentation and add a new test to prevent future regressions related to this specific regex behavior.

Highlights

• Documentation Fixed: Corrected the commandRegex example in docs/core/policy-engine.md by removing an incorrect ^ anchor that would never match due to how the pattern is tested.
• Clarity Added: Enhanced the commandRegex documentation with a note explaining that the pattern is tested against stringified JSON arguments, and that ^ should generally be avoided because it applies to the full JSON string, not just the command text.
• Regression Test Implemented: Introduced a new test case in packages/core/src/policy/toml-loader.test.ts to ensure commandRegex correctly handles the ^ anchor when matching against full JSON strings, preventing future regressions.

Changelog

• docs/core/policy-engine.md
  • Removed the ^ anchor from the commandRegex example.
  • Added a note explaining that commandRegex prepends "command":" to the pattern and that ^ should generally be avoided.
• packages/core/src/policy/toml-loader.test.ts
  • Added a new test case to verify that ^ in commandRegex causes a mismatch when matching against the full JSON string.

Activity

• The author has updated relevant documentation and added new tests.
• Validation on MacOS using npm run has been completed.

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[gemini-code-assist]

Code Review

This pull request clarifies the commandRegex documentation within the policy engine, correcting the understanding that the regex matches against the full JSON representation of arguments, and includes a regression test in toml-loader.test.ts. While these changes improve clarity and robustness, they also expose a critical architectural vulnerability. The policy engine's current method of matching commandRegex against a full JSON string of tool arguments allows for easy policy bypass through injection into non-validated fields, which could lead to unauthorized arbitrary command execution if an attacker can manipulate tool arguments. The remediation suggestion has been updated to reflect that toolCall.args must be parsed as a JSON string before accessing its properties.

[github-actions]

Size Change: -2 B (0%)

Total Size: 24.4 MB

ℹ️ View Unchanged

Filename	Size	Change
./bundle/gemini.js	24.4 MB	-2 B (0%)
./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

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