Skip to content

Data Structures

These are the primary data structures used in the interface between the QueryMT host and Extism plugins. They are typically serialized to/from JSON.

Many of these types are defined in querymt::chat, querymt::completion, and querymt::plugin::extism_impl::interface.

Core Request/Response Wrappers

These structures are used as the direct input/output for the main plugin functions (chat, embed, complete). They bundle the plugin-specific configuration (cfg) with the actual request payload.

  • querymt::plugin::extism_impl::ExtismChatRequest<C>

    • cfg: C: Plugin-specific configuration (type C is your plugin's config struct).
    • messages: Vec<ChatMessage>: The history of chat messages.
    • tools: Option<Vec<Tool>>: Optional list of tools the model can use.

  • querymt::plugin::extism_impl::ExtismEmbedRequest<C>

    • cfg: C: Plugin-specific configuration.
    • inputs: Vec<String>: List of texts to embed.

  • querymt::plugin::extism_impl::ExtismCompleteRequest<C>

    • cfg: C: Plugin-specific configuration.
    • req: CompletionRequest: The core completion request.

  • querymt::plugin::extism_impl::ExtismChatResponse (implements querymt::chat::ChatResponse)

    • text: Option<String>: The main textual response from the LLM.
    • tool_calls: Option<Vec<ToolCall>>: If the LLM decides to call tools.
    • thinking: Option<String>: Optional intermediate "thinking" messages.
    • usage: Option<Usage>: Optional token usage statistics.

Common Data Types

These are used within the request/response wrappers.

  • querymt::chat::ChatMessage

    • role: ChatRole: Enum (User, Assistant).
    • message_type: MessageType: An enum that determines the message content type.
    • content: String: The primary text content of the message.
    • Note on Tool Calls: Tool-related information is carried within the message_type field.
      • MessageType::ToolUse(Vec<ToolCall>): Used in an Assistant message to indicate the model's decision to call tools.
      • MessageType::ToolResult(Vec<ToolCall>): Used in a User message to provide the results of tool executions back to the model. In this case, the arguments field of each ToolCall contains the JSON string result of the function.

  • querymt::chat::Tool

    • tool_type: String: Typically "function".
    • function: FunctionTool: Describes the function tool.

  • querymt::chat::FunctionTool

    • name: String: Name of the function.
    • description: String: Description of the function.
    • parameters: serde_json::Value: JSON schema defining the function's parameters.

  • querymt::ToolCall

    • id: String: Unique ID for the tool call.
    • call_type: String: Typically "function".
    • function: FunctionCall: Details of the function to be called.

  • querymt::FunctionCall

    • name: String: Name of the function called.
    • arguments: String: JSON string of arguments for the function (or the result of the function, in a ToolResult message).

  • querymt::completion::CompletionRequest

    • prompt: String: The prompt for completion.
    • suffix: Option<String>
    • max_tokens: Option<u32>
    • temperature: Option<f32>

  • querymt::completion::CompletionResponse

    • text: String: The completed text.

For plugin developers using Rust, these types are readily available. When interacting via raw JSON, ensure your data conforms to these structures. The config_schema() export of a plugin should define the structure for the generic C (plugin configuration) part of the Extism*Request types.