feat(04-02): define AgentManager port interface and domain types

- AgentStatus type for agent lifecycle states
- SpawnAgentOptions for spawn configuration
- AgentInfo for agent state representation
- AgentResult for execution results
- AgentManager interface with spawn, stop, list, get, getByName, resume, getResult

src/agent/index.ts

@@ -0,0 +1,15 @@
+/**
+ * Agent Module - Public API
+ *
+ * Exports the AgentManager port interface and related types.
+ * All consumers should import from this index file.
+ */
+
+// Port interface and types
+export type {
+  AgentStatus,
+  SpawnAgentOptions,
+  AgentInfo,
+  AgentResult,
+  AgentManager,
+} from './types.js';

src/agent/types.ts

@@ -0,0 +1,136 @@
+/**
+ * Agent Module Types
+ *
+ * Port interface for agent lifecycle management.
+ * AgentManager is the PORT. Implementations are ADAPTERS.
+ */
+
+export type AgentStatus = 'idle' | 'running' | 'waiting_for_input' | 'stopped' | 'crashed';
+
+/**
+ * Options for spawning a new agent
+ */
+export interface SpawnAgentOptions {
+  /** Human-readable name for the agent (e.g., 'gastown', 'chinatown') */
+  name: string;
+  /** Task ID to assign to agent */
+  taskId: string;
+  /** Initial prompt/instruction for the agent */
+  prompt: string;
+  /** Optional working directory (defaults to worktree path) */
+  cwd?: string;
+}
+
+/**
+ * Represents a Claude agent instance
+ */
+export interface AgentInfo {
+  /** Unique identifier for this agent */
+  id: string;
+  /** Human-readable name for the agent */
+  name: string;
+  /** Task this agent is working on */
+  taskId: string;
+  /** Claude CLI session ID for resumption (null until first run completes) */
+  sessionId: string | null;
+  /** WorktreeManager worktree ID */
+  worktreeId: string;
+  /** Current status (waiting_for_input = paused on AskUserQuestion) */
+  status: AgentStatus;
+  /** When the agent was created */
+  createdAt: Date;
+  /** Last activity timestamp */
+  updatedAt: Date;
+}
+
+/**
+ * Result from agent execution
+ */
+export interface AgentResult {
+  /** Whether the task completed successfully */
+  success: boolean;
+  /** Result message or error description */
+  message: string;
+  /** Files modified during execution */
+  filesModified?: string[];
+}
+
+/**
+ * AgentManager Port Interface
+ *
+ * Manages Claude agent lifecycle - spawn, stop, list, resume.
+ *
+ * Covers requirements:
+ * - AGENT-01: Spawn new agent with task assignment
+ * - AGENT-02: Stop running agent
+ * - AGENT-03: List all agents with status
+ * - AGENT-04: Resume agent session
+ * - AGENT-05: Background mode (implementation detail)
+ */
+export interface AgentManager {
+  /**
+   * Spawn a new agent to work on a task.
+   *
+   * Creates isolated worktree, starts Claude SDK session,
+   * and begins executing the prompt.
+   *
+   * @param options - Spawn configuration
+   * @returns Agent info with session ID for later resumption
+   */
+  spawn(options: SpawnAgentOptions): Promise<AgentInfo>;
+
+  /**
+   * Stop a running agent.
+   *
+   * Gracefully stops the agent's work. Worktree is preserved
+   * for potential resumption.
+   *
+   * @param agentId - Agent to stop
+   */
+  stop(agentId: string): Promise<void>;
+
+  /**
+   * List all agents with their current status.
+   *
+   * @returns Array of all agents
+   */
+  list(): Promise<AgentInfo[]>;
+
+  /**
+   * Get a specific agent by ID.
+   *
+   * @param agentId - Agent ID
+   * @returns Agent if found, null otherwise
+   */
+  get(agentId: string): Promise<AgentInfo | null>;
+
+  /**
+   * Get a specific agent by name.
+   *
+   * @param name - Agent name (human-readable)
+   * @returns Agent if found, null otherwise
+   */
+  getByName(name: string): Promise<AgentInfo | null>;
+
+  /**
+   * Resume an agent that's waiting for input.
+   *
+   * Used when agent paused on AskUserQuestion and user provides response.
+   * Uses stored session ID to continue with full context.
+   * Agent must be in 'waiting_for_input' status.
+   *
+   * @param agentId - Agent to resume
+   * @param prompt - User's response to continue the agent
+   */
+  resume(agentId: string, prompt: string): Promise<void>;
+
+  /**
+   * Get the result of an agent's work.
+   *
+   * Only available after agent completes or stops.
+   *
+   * @param agentId - Agent ID
+   * @returns Result if available, null if agent still running
+   */
+  getResult(agentId: string): Promise<AgentResult | null>;
+}