- Refactor Gemini/OpenAI/Codex/Claude/Antigravity interaction and response translators to collect `parts`, `content`, `steps`, `tool_calls`, and `output` items in slices, then set each array once via `translatorcommon` helpers.
- Replace repeated incremental `sjson.SetRawBytes(..., ".-1", ...)` mutations with single-shot raw-array updates to avoid repeated rewrites.
- Keep existing step/content semantics while reducing ordering/overwrite risks when merging multi-fragment data (including thought/signature and web-search/function-call blocks).
- Enhanced response handling to support `response.incomplete` events across translator components and executors.
- Refactored `resultErrorFromError` to centralize error conversion and consolidate repeated logic for constructing custom errors.
- Updated handling of `max_output_tokens` and similar terminal reasons in OpenAI and Gemini translator workflows.
- Introduced `IsRequestScoped` and `IsRequestScopedError` to differentiate between request-scoped and non-request-scoped errors.
- Added comprehensive test cases for incomplete responses, terminal failures, and error propagation in both streaming and non-streaming conditions.
Closes: #3055
- Introduced API handlers and executor logic for Google Interactions
- Added request and response transformations for OpenAI and Claude Interactions.
- Integrated Gemini API with Interactions support.
- Updated tests to validate Interactions request parsing and error handling.
- Refactored translator logic for Interactions data flows.
