- Removed the unused `antigravity-user-agent.ts` file from the AI providers.
- Updated `parseStreamingJson` to trim only leading whitespace, try `JSON.parse` first, then partial parsing on repaired input before returning an empty object on failure.
- Removed a streaming JSON test that depended on preserving trailing spaces in incomplete string fragments.
- Optimized `repairJson` to scan JSON input incrementally and only patch invalid escape sequences or raw control characters.
- Reworked escape validation with byte-level constants and stricter `\uXXXX` handling for truncated or non-hex sequences.
- Added coverage for valid escapes, control-character repair, literal invalid-escape preservation, and whitespace-only streaming JSON inputs.
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