feat(acp): show the command in execute titles; test via the real bash tool; RFC for terminal rendering

- bash presentCall title is now "description — command" (e.g. "List files in
  src — ls -la src"). An execute-kind ACP card HIDES rawInput (Zed renders it
  only for non-terminal tools), so the command must ride in the always-visible
  title to be seen — matching how claude-agent-acp/codex-acp title execute
  tools. The command stays in rawInput too for non-execute UIs that show it.
- Rework the acp tool-call presentation tests (turns + load replay) to drive the
  REAL dsh-tool-bash + dsh-bash-local via a new makeBridgeHarness({ withBash })
  option, running an actual `echo` — instead of an inline fake bash tool. The
  mock MODEL still scripts the call (deterministic, no key), but the tool and
  executor are real, so the test verifies the shipping presentCall/presentResult.
- AGENTS.md: add the principle "prefer the REAL implementation over a mock/
  stand-in in tests" (mock only the expensive/non-deterministic boundary).
- RFC (proposed): the ACP terminal sub-protocol + command classification — the
  capability-gated rich rendering (live cwd-header terminal card, classify a
  `cat` as a read / `grep` as a search) that the reference adapters do; the
  fenced ```console text block stays the no-capability baseline. Studied
  codex-acp, claude-agent-acp, and Zed's renderer to ground it.

packages/acp/tests/load.spec.ts

@@ -4,7 +4,6 @@ import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { PROTOCOL_VERSION } from '@agentclientprotocol/sdk'
 import { SessionId } from '@deepseek-ai/dsh-session'
-import { defineTool } from '@deepseek-ai/dsh-tools'
 import { makeBridgeHarness, textResponse, toolCallResponse, type BridgeHarness, type CapturedUpdate } from './harness.ts'
 
 /** Concatenate the text of all agent_message_chunk updates. */
@@ -58,64 +57,37 @@ describe('acp bridge — session/load replay', () => {
   })
 
   it('replays a persisted tool call with the TOOL-OWNED presentation (title/rawInput/console output)', async () => {
-    // A turn with a tool call is persisted, then loaded by a fresh bridge. The
-    // replayed tool_call/tool_call_update must carry the tool's OWN presentation
-    // (presentCall/presentResult) — identical to how they streamed live — using
-    // a throwaway presenter that pairs call→result as the log replays in order.
+    // A turn with a REAL bash tool call is persisted, then loaded by a fresh
+    // bridge. The replayed tool_call/tool_call_update must carry the tool's OWN
+    // presentation — identical to how it streamed live — via a throwaway
+    // presenter that pairs call→result as the log replays in order. Uses the
+    // shipping tool (withBash), not a stand-in (AGENTS.md "prefer the real
+    // implementation over a mock in tests").
     live = await makeBridgeHarness({
       storageDir,
-      script: [toolCallResponse('c1', 'bash', { command: 'ls -la', description: 'List files' }), textResponse('done')],
+      withBash: true,
+      script: [toolCallResponse('c1', 'bash', { command: 'echo hello', description: 'Print a greeting' }), textResponse('done')],
     })
-    live.ctx.tools.register(defineTool({
-      name: 'bash',
-      description: 'run a command',
-      parameters: {
-        command: { type: 'string', required: true },
-        description: { type: 'string', required: true },
-      },
-      async execute() { return [{ type: 'text', text: 'a.txt\nb.txt\n' }] },
-      presentCall: args => ({ title: args.description, kind: 'execute', rawInput: args.command }),
-      presentResult: (_args, result) => {
-        const block = result.content.length === 1 ? result.content[0] : undefined
-        if (block === undefined || block.type !== 'text') return undefined
-        return { content: [{ type: 'text', text: `\`\`\`console\n${block.text.trimEnd()}\n\`\`\`` }] }
-      },
-    }))
     await live.client.initialize({ protocolVersion: PROTOCOL_VERSION, clientCapabilities: {} })
     const { sessionId } = await live.client.newSession({ cwd: process.cwd(), mcpServers: [] })
-    await live.client.prompt({ sessionId, prompt: [{ type: 'text', text: 'list' }] })
+    await live.client.prompt({ sessionId, prompt: [{ type: 'text', text: 'greet' }] })
     await live.dispose()
     live = undefined
 
-    // A fresh bridge — which must ALSO have the tool registered, since the
-    // presentation is resolved from the live registry at replay time — loads it.
-    loader = await makeBridgeHarness({ storageDir, script: [] })
-    loader.ctx.tools.register(defineTool({
-      name: 'bash',
-      description: 'run a command',
-      parameters: {
-        command: { type: 'string', required: true },
-        description: { type: 'string', required: true },
-      },
-      async execute() { return [] },
-      presentCall: args => ({ title: args.description, kind: 'execute', rawInput: args.command }),
-      presentResult: (_args, result) => {
-        const block = result.content.length === 1 ? result.content[0] : undefined
-        if (block === undefined || block.type !== 'text') return undefined
-        return { content: [{ type: 'text', text: `\`\`\`console\n${block.text.trimEnd()}\n\`\`\`` }] }
-      },
-    }))
+    // A fresh bridge — also with the real bash tool, since the presentation is
+    // resolved from the live registry at replay time — loads the session.
+    loader = await makeBridgeHarness({ storageDir, withBash: true, script: [] })
     await loader.client.initialize({ protocolVersion: PROTOCOL_VERSION, clientCapabilities: {} })
     await loader.client.loadSession({ sessionId, cwd: process.cwd(), mcpServers: [] })
 
     const call = loader.updates.find(u => u.sessionUpdate === 'tool_call')
-    expect(call).toMatchObject({ toolCallId: 'c1', title: 'List files', kind: 'execute', rawInput: 'ls -la' })
+    expect(call).toMatchObject({ toolCallId: 'c1', title: 'Print a greeting — echo hello', kind: 'execute', rawInput: 'echo hello' })
     const update = loader.updates.find(u => u.sessionUpdate === 'tool_call_update')
-    expect(update).toMatchObject({
-      toolCallId: 'c1',
-      status: 'completed',
-      content: [{ type: 'content', content: { type: 'text', text: '```console\na.txt\nb.txt\n```' } }],
-    })
+    expect(update?.sessionUpdate).toBe('tool_call_update')
+    if (update?.sessionUpdate !== 'tool_call_update') throw new Error('expected a tool_call_update')
+    expect(update).toMatchObject({ toolCallId: 'c1', status: 'completed' })
+    const content = update.content as { content: { text: string } }[]
+    expect(content[0]?.content.text).toBe('```console\nhello\n```')
   })
 
   it('a load whose resume finishes after a client disconnect leaks no live session', async () => {