backend

Candid Interface Definition

backend.did

This file defines the Candid interface for the backend canister. It specifies data types and service methods so that clients (frontend or other canisters) can interact with the backend.

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Type Definitions

AssistantMessage

type AssistantMessage = record {
  content : opt text;
  tool_calls : vec ToolCall;
};

• Represents a message from the assistant (e.g., an AI system).

• content — Optional text content of the message.

• tool_calls — A list of tools/functions the assistant is requesting to call.

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ChatMessage

type ChatMessage = variant {
  tool : record { content : text; tool_call_id : text };
  user : record { content : text };
  assistant : AssistantMessage;
  system : record { content : text };
};

• Represents a message in a conversation.

• tool — A tool response containing content and the tool_call_id that triggered it.

• user — A message sent by the user.

• assistant — A message from the assistant, including optional content and tool calls.

• system — A message from the system, usually containing instructions or context.

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FunctionCall

type FunctionCall = record {
  name : text;
  arguments : vec ToolCallArgument;
};

• Represents a call to a specific function.

• name — Name of the function to execute.

• arguments — List of named arguments passed to the function.

---

ToolCall

type ToolCall = record {
  id : text;
  function : FunctionCall;
};

• Represents a request to execute a tool or function.

• id — Unique identifier for this tool call.

• function — Details of the function to be executed.

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ToolCallArgument

type ToolCallArgument = record {
  value : text;
  name : text;
};

• Represents a single argument for a tool call.

• name — Name of the argument.

• value — Value of the argument.

---

Service Definition

service : {
  chat : (vec ChatMessage) -> (text);
  create_account : (text) -> (text);
  get_accounts : () -> (vec text) query;
  prompt : (text) -> (text);
}

Methods

1. chat

   • Input: A list of ChatMessage objects representing the conversation history.

   • Output: A text response from the assistant.

   • Purpose: Handles conversational interactions between the user and the assistant.

2. create_account

   • Input: text (account address).

   • Output: text status message ("Account created" or "Already exists").

   • Purpose: Adds a new account address to the backend’s account list.

3. get_accounts (query method)

   • Input: None.

   • Output: A vector of text values, each representing an account address.

   • Purpose: Retrieves all registered accounts without modifying state.

4. prompt

   • Input: text prompt.

   • Output: text response.

   • Purpose: Sends a single prompt to the assistant and returns its reply, without passing a full chat history.