feat(cli): port ACP to V2 (#37907)

packages/cli/test/acp/command.test.ts

@@ -0,0 +1,107 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import path from "node:path"
+
+type Message = { readonly id?: number; readonly result?: unknown; readonly error?: unknown }
+const children: Bun.Subprocess[] = []
+
+afterEach(async () => {
+  await Promise.all(
+    children.splice(0).map(async (child) => {
+      child.kill("SIGKILL")
+      await child.exited
+    }),
+  )
+})
+
+describe("acp command", () => {
+  test("is registered", async () => {
+    const result = await cli(["--help"])
+    expect(result.exitCode).toBe(0)
+    expect(result.stdout).toContain("acp        Start an Agent Client Protocol server")
+  })
+
+  test("initializes over ndjson and exits on stdin eof", async () => {
+    const child = spawn()
+    const stderr = new Response(child.stderr).text()
+    await child.stdin.write(
+      new TextEncoder().encode(
+        JSON.stringify({
+          jsonrpc: "2.0",
+          id: 1,
+          method: "initialize",
+          params: {
+            protocolVersion: 1,
+            clientCapabilities: {},
+            clientInfo: { name: "test", version: "1.0.0" },
+          },
+        }) + "\n",
+      ),
+    )
+    await child.stdin.flush()
+    const response = await readMessage(child.stdout)
+    expect(response.id).toBe(1)
+    expect(response.error).toBeUndefined()
+    expect(response.result).toMatchObject({
+      protocolVersion: 1,
+      agentCapabilities: { loadSession: true },
+      agentInfo: { name: "OpenCode" },
+    })
+
+    await child.stdin.end()
+    const exitCode = await child.exited
+    const errorOutput = await stderr
+    if (exitCode !== 0) throw new Error(`ACP exited with ${exitCode}: ${errorOutput}`)
+    children.splice(children.indexOf(child), 1)
+  }, 30_000)
+})
+
+function spawn() {
+  const child = Bun.spawn([process.execPath, "run", "src/index.ts", "acp"], {
+    cwd: path.join(import.meta.dir, "../.."),
+    stdin: "pipe",
+    stdout: "pipe",
+    stderr: "pipe",
+  })
+  children.push(child)
+  return child
+}
+
+async function readMessage(stream: ReadableStream<Uint8Array>) {
+  const reader = stream.getReader()
+  const decoder = new TextDecoder()
+  let output = ""
+  while (true) {
+    const result = await Promise.race([
+      reader.read(),
+      Bun.sleep(20_000).then(() => {
+        throw new Error("timed out waiting for ACP response")
+      }),
+    ])
+    if (result.done) throw new Error(`ACP exited before responding: ${output}`)
+    output += decoder.decode(result.value, { stream: true })
+    const newline = output.indexOf("\n")
+    if (newline === -1) continue
+    reader.releaseLock()
+    const message: unknown = JSON.parse(output.slice(0, newline))
+    if (!isMessage(message)) throw new Error(`invalid ACP response: ${output.slice(0, newline)}`)
+    return message
+  }
+}
+
+function isMessage(value: unknown): value is Message {
+  return typeof value === "object" && value !== null
+}
+
+async function cli(args: string[]) {
+  const child = Bun.spawn([process.execPath, "run", "src/index.ts", ...args], {
+    cwd: path.join(import.meta.dir, "../.."),
+    stdout: "pipe",
+    stderr: "pipe",
+  })
+  const [stdout, stderr, exitCode] = await Promise.all([
+    new Response(child.stdout).text(),
+    new Response(child.stderr).text(),
+    child.exited,
+  ])
+  return { stdout, stderr, exitCode }
+}