fix(gemini-translator): sanitize stale required entries in OpenAI tool schemas

[myagizmaktav]

Summary

Fix AI_APICallError: GenerateContentRequest.tools[0].function_declarations[N].parameters.required[M]: property is not defined raised by Gemini API when an OpenAI Chat Completions / Responses tool declares required entries that are missing from properties.

The OpenAI → Gemini translator renamed tools[].function.parameters to parametersJsonSchema but never ran the renamed payload through util.CleanJSONSchemaForGemini. Other translators (claude→gemini, antigravity→gemini) already do so for the same reason. Without that sanitization, cleanupRequiredFields is skipped and every stale required name is forwarded to Gemini, which then rejects the request with the API error above.

Changes

• internal/translator/gemini/openai/chat-completions/gemini_openai_request.go
  After renaming parameters → parametersJsonSchema, run the renamed value through util.CleanJSONSchemaForGemini. This calls cleanupRequiredFields (which intersects required with properties, removing any name that does not have a corresponding property) and also flattens anyOf/oneOf/allOf, removes unsupported keywords, normalizes enums, and strips x-* extension fields — all of which Gemini API rejects.
• internal/translator/gemini/openai/responses/gemini_openai-responses_request.go
  Same fix for the OpenAI Responses translator.

Tests

New regression tests in:

• internal/translator/gemini/openai/chat-completions/gemini_openai_request_sanitize_test.go
  • TestConvertOpenAIRequestToGemini_SanitizesStaleRequiredEntries — pins down the original bug.
  • TestConvertOpenAIRequestToGemini_DropsEmptyRequiredArray — confirms the all-stale case is fully removed.
  • TestConvertOpenAIRequestToGemini_AllRequiredValidPassesThrough — guards against regressions in the happy path.
• internal/translator/gemini/openai/responses/gemini_openai-responses_request_sanitize_test.go
  • TestConvertOpenAIResponsesRequestToGemini_SanitizesStaleRequiredEntries — same coverage for the responses translator.

All tests in the touched packages pass, gofmt is clean, and go build -o test-output ./cmd/server && rm test-output (the AGENTS.md compile guard) succeeds.

Fixes #3863

[github-actions]

This pull request targeted main.

The base branch has been automatically changed to dev.

[gemini-code-assist]

Code Review

This pull request introduces JSON schema sanitization for Gemini API compatibility in both the chat-completions and responses translators, resolving API errors caused by stale required fields. Unit tests are also added to verify the sanitization logic. The review feedback suggests optimizing this process by sanitizing only the nested parameters schema directly rather than the entire function declaration, which reduces performance overhead and avoids potential side effects on non-schema fields.

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