test(subagent-acp): cover inherited cwd through a Loader composition

The inheritance branch ran only under hand-mounted plugin tests, and
the with-key e2e always configures an explicit cwd. Add a test-only
cordis.yml (scripted delegating model + the scripted mock ACP child)
booting the stdio app through the real Loader with cwd omitted: the
child proves it ran in — and was announced — the parent session's
workspace, keylessly.

examples/acp-agent/tests/fixtures/subagent/subagent-acp/cordis.yml

@@ -0,0 +1,37 @@
+# Test-only composition: the ACP subagent backend on the real Loader/app path.
+# The scripted model delegates once; the scripted mock ACP child (MOCK_ECHO_CWD)
+# echoes its process cwd and announced session cwd, so parent-session cwd
+# inheritance is asserted keylessly end to end. `cwd` is deliberately omitted —
+# the inheritance branch under test. The child command path is machine-absolute,
+# so the driving e2e supplies it via DSH_TEST_MOCK_ACP_SERVER.
+- id: mock-llm
+  name: './mock-delegating-llm.ts'
+
+- id: subagent
+  name: '@deepseek-ai/dsh-subagent'
+
+- id: subagent-acp
+  name: '@deepseek-ai/dsh-subagent-acp'
+  config:
+    providerName: acp
+    command: !!js process.execPath
+    args:
+      - !!js process.env.DSH_TEST_MOCK_ACP_SERVER
+    permission: reject
+    env:
+      MOCK_ECHO_CWD: '1'
+
+- id: tool-subagent
+  name: '@deepseek-ai/dsh-tool-subagent'
+  config:
+    provider: acp
+    toolName: subagent
+
+- id: stdio-agent
+  name: '@deepseek-ai/dsh-stdio-demo'
+  config:
+    provider: mock
+    model: mock-delegate
+    welcome: 'acp subagent cwd e2e ready.'
+    persistenceRoot: './.sessions'
+    workspaceContext: false

examples/acp-agent/tests/fixtures/subagent/subagent-acp/mock-delegating-llm.ts

@@ -0,0 +1,48 @@
+import type { Context } from 'cordis'
+import type { GenerateOptions, StreamChunk } from '@deepseek-ai/dsh-llm'
+import { CallId, LlmAdapter } from '@deepseek-ai/dsh-llm'
+
+/**
+ * Test adapter for the `mock-delegate` model: the first request calls the
+ * `subagent` tool once, and the follow-up streams the tool result text back
+ * verbatim — so the ACP child's answer (the scripted mock server's cwd echo)
+ * reaches the REPL stdout for the driving e2e to assert.
+ */
+class MockDelegatingAdapter extends LlmAdapter {
+  async * stream(options: GenerateOptions): AsyncIterable<StreamChunk> {
+    const toolResultText = options.messages.at(-1)?.content
+      .filter(block => block.type === 'tool-result')
+      .flatMap(block => block.content)
+      .filter(block => block.type === 'text')
+      .map(block => block.text)
+      .join('') ?? ''
+
+    if (toolResultText.length === 0) {
+      const args = JSON.stringify({ description: 'cwd probe', prompt: 'report your workspace' })
+      yield { type: 'block-start', index: 0, blockType: 'tool-call' }
+      yield { type: 'tool-call-delta', index: 0, id: CallId('call-delegate'), name: 'subagent', argumentsDelta: args }
+      yield { type: 'block-end', index: 0, block: { type: 'tool-call', id: CallId('call-delegate'), name: 'subagent', arguments: args } }
+      yield { type: 'usage', usage: { inputTokens: 10, outputTokens: 5 } }
+      yield { type: 'finish', reason: { kind: 'tool-calls' } }
+      return
+    }
+
+    const reply = `child reported:\n${toolResultText}`
+    yield { type: 'block-start', index: 0, blockType: 'text' }
+    yield { type: 'text-delta', index: 0, text: reply }
+    yield { type: 'block-end', index: 0, block: { type: 'text', text: reply } }
+    yield { type: 'usage', usage: { inputTokens: 10, outputTokens: reply.length } }
+    yield { type: 'finish', reason: { kind: 'stop' } }
+  }
+}
+
+export const name = 'mock-llm'
+export const inject = ['llm']
+
+/**
+ * Register the delegating mock adapter under the `mock` provider.
+ * @param ctx - the plugin context supplying `ctx.llm`.
+ */
+export function apply(ctx: Context): void {
+  ctx.llm.registerAdapter(['mock'], new MockDelegatingAdapter())
+}

examples/package.json

@@ -30,6 +30,7 @@
     "@deepseek-ai/dsh-spill-policy": "workspace:*",
     "@deepseek-ai/dsh-stdio-demo": "workspace:*",
     "@deepseek-ai/dsh-subagent": "workspace:*",
+    "@deepseek-ai/dsh-subagent-acp": "workspace:*",
     "@deepseek-ai/dsh-subagent-fork": "workspace:*",
     "@deepseek-ai/dsh-subagent-spawn": "workspace:*",
     "@deepseek-ai/dsh-time-context": "workspace:*",