feat(agent): improve investigation contracts and runtime readiness

tests/routes/chatStreamLifecycle.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "bun:test";
 import { streamPromptResponse } from "../../src/routes/chatStream.js";
-import type { OpencodeRuntimeAdapter } from "../../src/runtime/opencode.js";
+import { McpPreparationError, type OpencodeRuntimeAdapter } from "../../src/runtime/opencode.js";
 
 type Output = { event: string; data: Record<string, unknown> };
 const textStart = { type: "message.part.updated", properties: { sessionID: "s", part: { id: "text", type: "text", text: "" } } };
@@ -143,3 +143,21 @@ describe("stream stage boundaries", () => {
     expect(output.some((item) => item.event === "progress" && item.data.id === "query")).toBe(false);
   });
 });
+
+
+it("propagates MCP_NOT_READY without completing an artifact-free investigation", async () => {
+  const output: Output[] = [];
+  const failure = new McpPreparationError("等待业务工具目录就绪超时");
+  let completionChecks = 0;
+  const runtime = createRuntime({ [Symbol.asyncIterator]: () => ({
+    next: () => new Promise<IteratorResult<unknown>>(() => {}),
+    return: async () => ({ done: true as const, value: undefined }),
+  }) }, { prompt: async () => { throw failure; } });
+  let caught: unknown;
+  try { await run(runtime, output, { beforeIdle: async () => { completionChecks++; return true; } }); }
+  catch (error) { caught = error; }
+  expect(caught).toBe(failure);
+  expect(caught).toMatchObject({ code: "MCP_NOT_READY" });
+  expect(completionChecks).toBe(0);
+  expect(output.some((item) => ["tool_call", "final_answer", "done"].includes(item.event))).toBe(false);
+});