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/server.ts

@@ -0,0 +1,53 @@
+import { AgentSideConnection, ndJsonStream } from "@zed-industries/agent-client-protocol"
+import { Log } from "../util/log"
+import { Instance } from "../project/instance"
+import { OpenCodeAgent } from "./agent"
+
+export namespace ACPServer {
+  const log = Log.create({ service: "acp-server" })
+
+  export async function start() {
+    await Instance.provide({
+      directory: process.cwd(),
+      fn: async () => {
+        log.info("starting ACP server", { cwd: process.cwd() })
+
+        const stdout = new WritableStream({
+          write(chunk) {
+            process.stdout.write(chunk)
+          },
+        })
+
+        const stdin = new ReadableStream({
+          start(controller) {
+            process.stdin.on("data", (chunk) => {
+              controller.enqueue(new Uint8Array(chunk))
+            })
+            process.stdin.on("end", () => {
+              controller.close()
+            })
+          },
+        })
+
+        const stream = ndJsonStream(stdout, stdin)
+
+        new AgentSideConnection((conn) => {
+          return new OpenCodeAgent(conn)
+        }, stream)
+
+        await new Promise<void>((resolve) => {
+          process.on("SIGTERM", () => {
+            log.info("received SIGTERM")
+            resolve()
+          })
+          process.on("SIGINT", () => {
+            log.info("received SIGINT")
+            resolve()
+          })
+        })
+
+        log.info("ACP server stopped")
+      },
+    })
+  }
+}