#17914: Resolve merge conflicts in PR #13361

Resolved merge conflicts in and . Verified with tests. <!-- greptile_comment --> <h3>Greptile Summary</h3> This PR resolves merge conflicts from PR #13361, which fixes thinking block signature handling for Google Antigravity Claude models. The core change ensures that `sanitizeAntigravityThinkingBlocks` normalizes **both** `thinkingSignature` and `signature` fields on thinking blocks, rather than only `thinkingSignature`. Previously, a block with only a `signature` field would get `thinkingSignature` added but retain its original `signature` untouched — meaning if the signature came from a different field (e.g., `thought_signature`), only `thinkingSignature` would be set while `signature` remained absent. This caused downstream issues with Claude thinking models on the Google Antigravity API. - `sanitizeAntigravityThinkingBlocks` in `google.ts` now sets both `thinkingSignature` and `signature` to the resolved candidate value, and the normalization condition checks both fields - Test file updated to assert both `thinkingSignature` and `signature` are present after sanitization, and `modelId` is now passed in relevant test cases to correctly trigger the Antigravity Claude policy path - The merge conflict resolution commit cleanly integrates these changes with the current `main` branch <h3>Confidence Score: 4/5</h3> - This PR is safe to merge — the logic change is narrow, correct, and well-covered by updated tests. - The changes are focused and straightforward: extending an existing normalization function to also populate the `signature` field alongside `thinkingSignature`. The condition logic (`||` instead of single check) is correct for all edge cases (both fields present, only one present, neither present). The test updates properly exercise the new behavior and add `modelId` to trigger the correct policy path. The double-cast through `unknown` is the standard TypeScript pattern for adding fields not in the original type. No security concerns or risky patterns. - No files require special attention _{Last reviewed commit: cc3f792} <!-- greptile_other_comments_section --> _{(4/5) You can add custom instructions or style guidelines for the agent [here](https://app.greptile.com/review/github)!} <!-- /greptile_comment -->