# Task ID: 146

**Title:** AgentRuntime interface definition

**Status:** pending

**Dependencies:** None

**Priority:** medium

**Description:** Define AgentRuntime adapter interface for swappable agent implementations

**Details:**

Create src/mcpd/src/services/agent-runtime.ts:
1. Define RuntimeSessionOpts: { agentId, projectId, taskId?, image, persona (prompt files) }
2. Define RuntimeStatus: 'starting' | 'running' | 'completed' | 'failed'
3. Define RuntimeResult: { branch: string, headCommit: string, summary: string, prUrl?: string }
4. Define AgentRuntime interface:
   - startSession(opts: RuntimeSessionOpts): Promise<{ sessionId: string }>
   - send(sessionId: string, message: string): Promise<void>
   - status(sessionId: string): Promise<RuntimeStatus>
   - result(sessionId: string): Promise<RuntimeResult>
   - endSession(sessionId: string): Promise<void>
5. This is an interface, not an implementation - allows swapping runtimes later

**Test Strategy:**

Type tests: verify interface can be implemented, verify all methods have correct signatures.