google

Overview ¶

Package google exposes native Gemini chat, embedding, image, speech, transcription, and token-estimation adapters. NewChatCompletions targets Gemini's OpenAI-compatible chat endpoint. Native chat maps a natural stop with function calls to Core tool_calls while preserving interrupted and invalid-call outcomes and the native finish reason. Core ToolCall.ID is replayed unchanged on the call and its matching result, including IDs synthesized when the provider omitted one. Native chat request extensions use the SDK's camelCase JSON fields only. GenerateContent has one native decoder shared by unary and streaming calls. SDK DTOs and authentication are reused; SDK response converters and automatic continuation are not executed. HTTP extensions allow headers and timeout only. Core Citation owns validation of native citations with a URI. Invalid citations fail Call and Stream rather than disappearing from a successful response. Citation-only chunks reach Core's accumulator, which owns text attachment. Sampling, output format, reasoning effort, system messages, function tools, and tool choice belong to Core; attempts to set them again in native config are rejected even when the Core value is absent. Native safety, grounding, modalities, and thinking-budget settings remain available. Thought signatures retain their original Part positions across streaming, history serialization, and replay. Signature-only Parts carry opaque Core reasoning state without visible reasoning text. Core Part.Kind owns the thought classification of visible text. Native part_state retains the independent flag on signature-only, tool, and media Parts. Stored visible-text state containing a competing thought flag is rejected. Native embedding extensions also use SDK camelCase fields and reject outputDimensionality; embedding.Options.Dimensions owns that value. Embedding responses retain the exact native JSON. Optional token, truncation, and billing metadata is projected only when reported, including zero and false.

Constructors take a context because construction reaches the network. On the Vertex AI backend with application default credentials, building the client resolves them and then asks the resolved credential for its quota project, which is a metadata-server call the context governs — so a caller can bound or cancel its own wiring instead of a background context deciding for it. NewChatCompletions is the exception: it builds an OpenAI-compatible client and performs no I/O.

NewSpeechModel performs unary-only Gemini 2.5 speech synthesis. Unary speech and transcription require a STOP finish reason. Truncated, blocked, or unterminated generation returns the modality's ErrInvalidResponse without presenting partial content as a completed response. Gemini 3.1 uses NewStreamingSpeechModel: Call aggregates Stream, and both require successful stream completion. Call discards partial audio on error. Native speech_response metadata describes the latest stream event, not a fabricated unary response. Request model overrides must stay in that capability.