Module gemini 

The Google Gemini adapter (DW-075).

Speaks the Gemini generateContent API (POST /v1beta/models/{model}:generateContent — note the model rides in the PATH, not the body, which is why ProviderAdapter::build_request takes the provider model explicitly). Translation notes:

• System messages lift to systemInstruction.
• Roles are user/model only; OpenAI tool results become user turns carrying a functionResponse part. Gemini requires the FUNCTION NAME there, while the OpenAI shape carries only the call id — the adapter resolves the name by scanning backward through the conversation for the assistant tool_calls entry with that id, and falls back to the id itself when the history does not contain it (a client that invented a tool_call_id out of thin air).
• Tool declarations become functionDeclarations; the JSON-Schema parameters object is passed through minus $schema (which Gemini rejects).
• data: URI images become inline_data parts; remote image URLs have no Gemini equivalent in this API and are DROPPED (documented limitation of the translation, not a silent corruption — the alternative, fetching the URL, is a side effect a gateway must not invent).
• Finish reasons map STOP -> stop, MAX_TOKENS -> length, SAFETY/PROHIBITED_CONTENT -> content filter, RECITATION -> other. Usage maps promptTokenCount/candidatesTokenCount.
• Streaming uses :streamGenerateContent?alt=sse; each SSE data payload is a GenerateContentResponse translated like a single-choice fragment.

Structs

GeminiAdapter

The Gemini generateContent adapter. Stateless singleton.