fix: accept acp slash commands

Author: thymikee

src/acp/__tests__/prompt-lines.test.ts

@@ -25,6 +25,18 @@ test('strips an optional leading agent-device token', () => {
   assert.equal((line as RunnableLine).command, 'devices');
 });
 
+test('accepts ACP slash commands for advertised commands', () => {
+  const lines = parsePromptCommandLines('/devices\n/snapshot -i', { cwd: CWD });
+  assert.deepEqual(
+    lines.map((line) => {
+      assert.equal(line.kind, 'command');
+      return (line as RunnableLine).command;
+    }),
+    ['devices', 'snapshot'],
+  );
+  assert.equal((lines[1] as RunnableLine).flags.snapshotInteractiveOnly, true);
+});
+
 test('tokenizes quoted arguments with spaces like replay scripts', () => {
   const line = parseOne('fill "id:search" "hello world" --platform ios');
   assert.equal(line.kind, 'command');

src/acp/__tests__/router.test.ts

@@ -200,6 +200,31 @@ test('unknown methods, unknown sessions, and bad params return JSON-RPC errors',
   assert.equal(unknownSession.error.code, -32602);
 });
 
+test('session/new requires protocol-shaped session params', async () => {
+  const harness = makeRouter();
+  const cases: Array<{ name: string; params: unknown; message: RegExp }> = [
+    { name: 'relative cwd', params: { cwd: 'relative', mcpServers: [] }, message: /absolute/ },
+    { name: 'missing mcpServers', params: { cwd: '/tmp' }, message: /mcpServers/ },
+    { name: 'non-array mcpServers', params: { cwd: '/tmp', mcpServers: {} }, message: /array/ },
+    {
+      name: 'non-object mcpServers entry',
+      params: { cwd: '/tmp', mcpServers: [42] },
+      message: /mcpServers\[0\]/,
+    },
+  ];
+
+  for (const [index, entry] of cases.entries()) {
+    const response = (await harness.router.handleAcpPayload({
+      jsonrpc: '2.0',
+      id: index + 1,
+      method: 'session/new',
+      params: entry.params,
+    })) as { error: { code: number; message: string } };
+    assert.equal(response.error.code, -32602, entry.name);
+    assert.match(response.error.message, entry.message, entry.name);
+  }
+});
+
 test('notifications get no response and cancel notifications mark the session', async () => {
   let observedCancelled = false;
   const harness = makeRouter(

src/acp/prompt-lines.ts

@@ -60,6 +60,7 @@ function parsePromptCommandLine(line: string, options: { cwd: string }): PromptL
     return { kind: 'error', line, error: error instanceof Error ? error.message : String(error) };
   }
   if (tokens[0] === 'agent-device') tokens = tokens.slice(1);
+  if (tokens[0]?.startsWith('/')) tokens = [tokens[0].slice(1), ...tokens.slice(1)];
   if (tokens.length === 0) {
     return { kind: 'error', line, error: 'Empty command line.' };
   }

src/acp/router.ts

@@ -1,3 +1,4 @@
+import { isAbsolute } from 'node:path';
 import { listMcpCommandMetadata } from '../commands/command-metadata.ts';
 import { jsonRpcRequestSchema, type JsonRpcId } from '../kernel/contracts.ts';
 import { errorResponse, successResponse, type JsonRpcResponse } from '../mcp/router.ts';
@@ -50,7 +51,7 @@ export function createAcpRouter(deps: {
   };
 
   const newSession = (params: unknown): { sessionId: string } => {
-    const cwd = stringField(asRecord(params), 'cwd');
+    const { cwd } = readSessionNewParams(params);
     const session = sessions.create(cwd);
     // The session/new response must reach the client before the first
     // notification for that session; the response is written when this handler
@@ -121,6 +122,27 @@ export function createAcpRouter(deps: {
   };
 }
 
+function readSessionNewParams(params: unknown): { cwd: string } {
+  const record = asRecord(params);
+  const cwd = stringField(record, 'cwd');
+  if (!isAbsolute(cwd)) {
+    throw new AcpInvalidParamsError('Expected cwd to be an absolute path.');
+  }
+  validateMcpServers(record.mcpServers);
+  return { cwd };
+}
+
+function validateMcpServers(value: unknown): void {
+  if (!Array.isArray(value)) {
+    throw new AcpInvalidParamsError('Expected mcpServers to be an array.');
+  }
+  for (const [index, entry] of value.entries()) {
+    if (!asOptionalRecord(entry)) {
+      throw new AcpInvalidParamsError(`Expected mcpServers[${index}] to be an object.`);
+    }
+  }
+}
+
 function markCancelled(
   getSession: (id: string) => AcpSessionState | undefined,
   params: unknown,

website/docs/docs/agent-setup.md

@@ -92,7 +92,7 @@ Registry metadata uses MCP name `io.github.callstackincubator/agent-device`, npm
 
 ## ACP agent (Zed and other ACP clients)
 
-`agent-device acp` starts a stdio [ACP](https://agentclientprotocol.com/) (Agent Client Protocol) agent, so ACP clients such as Zed can drive devices from the agent panel. It is a deterministic agent, not an LLM: each line of a prompt is one agent-device command in CLI syntax (an optional leading `agent-device` is accepted), executed through the same command contracts and `AgentDeviceClient` path as MCP tools. Command executions stream back as ACP tool calls with daemon progress updates, screenshots attach as inline images, and available commands are advertised per session.
+`agent-device acp` starts a stdio [ACP](https://agentclientprotocol.com/) (Agent Client Protocol) agent, so ACP clients such as Zed can drive devices from the agent panel. It is a deterministic agent, not an LLM: each line of a prompt is one agent-device command in CLI syntax (ACP slash commands such as `/devices` and an optional leading `agent-device` are accepted), executed through the same command contracts and `AgentDeviceClient` path as MCP tools. Command executions stream back as ACP tool calls with daemon progress updates, screenshots attach as inline images, and available commands are advertised per session.
 
 Target selection sticks within a session: after `open com.example.app --platform ios`, later lines such as `snapshot -i` reuse the same `--platform`, `--device`, `--udid`, `--session`, and `--state-dir` values until a line overrides them. Project config resolution uses the working directory the ACP client passes on `session/new`.
 
@@ -114,7 +114,7 @@ Prompts are literal command lines, one per line:
 
 ```
 open com.example.app --platform ios
-snapshot -i
+/snapshot -i
 press @e2
 screenshot
 close