feat: Add ACP (Agent Client Protocol) support (#2947)

Co-authored-by: opencode-bot <devnull@opencode.local>
Co-authored-by: Dax Raad <d@ironbay.co>
Co-authored-by: GitHub Action <action@github.com>

packages/opencode/src/acp/session.ts

@@ -0,0 +1,60 @@
+import type { McpServer } from "@zed-industries/agent-client-protocol"
+import { Identifier } from "../id/id"
+import { Session } from "../session"
+import type { ACPSessionState } from "./types"
+
+export class ACPSessionManager {
+  private sessions = new Map<string, ACPSessionState>()
+
+  async create(cwd: string, mcpServers: McpServer[]): Promise<ACPSessionState> {
+    const sessionId = `acp_${Identifier.ascending("session")}`
+    const openCodeSession = await Session.create({ title: `ACP Session ${sessionId}` })
+
+    const state: ACPSessionState = {
+      id: sessionId,
+      cwd,
+      mcpServers,
+      openCodeSessionId: openCodeSession.id,
+      createdAt: new Date(),
+    }
+
+    this.sessions.set(sessionId, state)
+    return state
+  }
+
+  get(sessionId: string): ACPSessionState | undefined {
+    return this.sessions.get(sessionId)
+  }
+
+  async remove(sessionId: string): Promise<void> {
+    const state = this.sessions.get(sessionId)
+    if (!state) return
+
+    await Session.remove(state.openCodeSessionId).catch(() => {})
+    this.sessions.delete(sessionId)
+  }
+
+  has(sessionId: string): boolean {
+    return this.sessions.has(sessionId)
+  }
+
+  async load(sessionId: string, cwd: string, mcpServers: McpServer[]): Promise<ACPSessionState> {
+    const existing = this.sessions.get(sessionId)
+    if (existing) {
+      return existing
+    }
+
+    const openCodeSession = await Session.create({ title: `ACP Session ${sessionId} (loaded)` })
+
+    const state: ACPSessionState = {
+      id: sessionId,
+      cwd,
+      mcpServers,
+      openCodeSessionId: openCodeSession.id,
+      createdAt: new Date(),
+    }
+
+    this.sessions.set(sessionId, state)
+    return state
+  }
+}