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/cli/cmd/acp.ts

@@ -0,0 +1,21 @@
+import type { CommandModule } from "yargs"
+import { ACPServer } from "../../acp/server"
+
+export const AcpCommand: CommandModule = {
+  command: "acp",
+  describe: "Start ACP (Agent Client Protocol) server",
+  builder: (yargs) => {
+    return yargs.option("cwd", {
+      describe: "working directory",
+      type: "string",
+      default: process.cwd(),
+    })
+  },
+  handler: async (opts) => {
+    if (opts["cwd"] && typeof opts["cwd"] === "string") {
+      process.chdir(opts["cwd"])
+    }
+
+    await ACPServer.start()
+  },
+}