# Gemini Special Handling



Acontext handles Gemini-specific features including `thinking` parts for [Gemini thinking](https://ai.google.dev/gemini-api/docs/thinking) and automatic function call ID generation.

## Thinking Parts [#thinking-parts]

Acontext natively stores Gemini thinking parts. The `ThoughtSignature` is base64-encoded and preserved for multi-turn continuity.

<CodeGroup>
  ```python title="Python"
  client.sessions.store_message(
      session_id=session.id,
      blob={
          "role": "model",
          "parts": [
              {
                  "text": "Let me reason step by step...",
                  "thought": True,
                  "thoughtSignature": "Z2VtaW5pLXRob3VnaHQtc2ln..."
              },
              {
                  "text": "The answer is 42."
              }
          ]
      },
      format="gemini"
  )

  # Retrieved in Gemini format: thinking parts round-trip with Thought flag and ThoughtSignature
  # Retrieved in Anthropic format: thinking parts round-trip as native thinking blocks
  # Retrieved in OpenAI format: thinking content is downgraded to plain text
  ```

  ```typescript title="TypeScript"
  await client.sessions.storeMessage(session.id, {
      role: "model",
      parts: [
          {
              text: "Let me reason step by step...",
              thought: true,
              thoughtSignature: "Z2VtaW5pLXRob3VnaHQtc2ln..."
          },
          {
              text: "The answer is 42."
          }
      ]
  }, { format: "gemini" });

  // Retrieved in Gemini format: thinking parts round-trip with Thought flag and ThoughtSignature
  // Retrieved in Anthropic format: thinking parts round-trip as native thinking blocks
  // Retrieved in OpenAI format: thinking content is downgraded to plain text
  ```
</CodeGroup>

## Function Call ID Generation [#function-call-id-generation]

Gemini `FunctionCall` parts may omit the `id` field. Acontext automatically generates a unique ID (format: `call_<8-char-hex>`) for each function call without one, and stores the ID-to-name mapping in message metadata so that `FunctionResponse` parts can be matched back correctly.

<CodeGroup>
  ```python title="Python"
  # Store a model message with a FunctionCall (no ID needed)
  client.sessions.store_message(
      session_id=session.id,
      blob={
          "role": "model",
          "parts": [
              {
                  "functionCall": {
                      "name": "get_weather",
                      "args": {"city": "San Francisco"}
                  }
              }
          ]
      },
      format="gemini"
  )

  # Store the FunctionResponse — Acontext resolves the tool_call_id automatically
  client.sessions.store_message(
      session_id=session.id,
      blob={
          "role": "user",
          "parts": [
              {
                  "functionResponse": {
                      "name": "get_weather",
                      "response": {"temperature": "72°F", "condition": "sunny"}
                  }
              }
          ]
      },
      format="gemini"
  )
  ```

  ```typescript title="TypeScript"
  // Store a model message with a FunctionCall (no ID needed)
  await client.sessions.storeMessage(session.id, {
      role: "model",
      parts: [
          {
              functionCall: {
                  name: "get_weather",
                  args: { city: "San Francisco" }
              }
          }
      ]
  }, { format: "gemini" });

  // Store the FunctionResponse — Acontext resolves the tool_call_id automatically
  await client.sessions.storeMessage(session.id, {
      role: "user",
      parts: [
          {
              functionResponse: {
                  name: "get_weather",
                  response: { temperature: "72°F", condition: "sunny" }
              }
          }
      ]
  }, { format: "gemini" });
  ```
</CodeGroup>

<Tip>
  Thinking parts stored from any provider (Anthropic or Gemini) are cross-compatible. Retrieve in any format and Acontext converts automatically. See [Multi-provider Messages](/store/messages/multi-provider) for details.
</Tip>