/**
 * Minimal provider-agnostic LLM contract. The rest of the AI module only
 * depends on this interface, so swapping Anthropic for another vendor (or a
 * self-hosted model) is a one-file change.
 */
export interface LlmMessage {
  role: 'user' | 'assistant';
  content: string | LlmContentBlock[];
}

export type LlmContentBlock =
  | { type: 'text'; text: string }
  | { type: 'tool_use'; id: string; name: string; input: Record<string, unknown> }
  | { type: 'tool_result'; toolUseId: string; content: string; isError?: boolean };

export interface LlmTool {
  name: string;
  description: string;
  inputSchema: Record<string, unknown>; // JSON schema
}

export interface LlmRequest {
  system: string;
  messages: LlmMessage[];
  tools?: LlmTool[];
  maxTokens?: number;
  temperature?: number;
  /** Force a JSON object answer (provider may use native structured output or prompting). */
  json?: boolean;
}

export interface LlmResponse {
  text: string;
  toolCalls: { id: string; name: string; input: Record<string, unknown> }[];
  stopReason: 'end' | 'tool_use' | 'max_tokens' | 'other';
  usage: { inputTokens: number; outputTokens: number };
  model: string;
}

export interface LlmProvider {
  readonly name: string;
  readonly model: string;
  complete(req: LlmRequest): Promise<LlmResponse>;
}

export const LLM_PROVIDER = Symbol('LLM_PROVIDER');