feat(pi-subagents): 重新启用子 Agent 并使用独立的子 Agent 提示词

- 根包恢复 file:./pi-subagents 依赖与 extensions/subagents.ts 加载
  （排在 permission-system 之后、Tool Search 之前），并刷新根锁文件；
  Agent / get_subagent_result / steer_subagent 权限设为 allow，
  子 Agent 内的实际操作仍逐个经权限系统并转发主会话。
- 新增 config/prompt/subagent/：执行者角色 preamble 与组合包自带的
  general-purpose / Explore / Plan 定义（替换上游内置，去掉 bash find
  冲突规则与写死的 Haiku 模型）。
- pi-subagents 新增 basePrompt / bundledAgentsDir / excludedExtensionPaths
  选项：子 Agent 不再嵌入父会话提示词，身份标记置于开头；子会话排除
  pi-ask-user。未传选项时保持上游行为。
- system-prompt.ts：customPrompt 自带开场白时不再覆盖（修复子 Agent 角色
  与 <active_agent> 身份被抹掉）；仅凭 customPrompt 上的 <active_agent>
  识别子会话，routing 规则支持 scope，sections 支持 subagentExclude
  （子会话去掉 memory_policy 与 chrome_profile_bridge）。
- pi-hermes-memory：子会话只读，记忆/skill 写入工具返回错误，后台整理、
  纠错检测、会话 flush 与索引写入全部跳过。

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

tests/extension-load.test.ts

@@ -10,19 +10,38 @@ import test from "node:test";
 const repositoryRoot = resolve(dirname(fileURLToPath(import.meta.url)), "..");
 const hasPi = spawnSync("pi", ["--version"], { encoding: "utf8" }).status === 0;
 
-test("subagents source is retained but disabled in the root bundle", async () => {
+test("enabled subagents wrapper loads with its bundle-owned mandatory permission entry", { skip: !hasPi }, async () => {
   const packageJson = JSON.parse(await readFile(join(repositoryRoot, "package.json"), "utf8")) as {
     dependencies: Record<string, string>;
     files: string[];
     pi: { extensions: string[] };
   };
-  assert.ok(packageJson.files.includes("pi-subagents"), "the bundle must retain the maintained subagents source");
-  assert.equal(packageJson.dependencies["@tintinweb/pi-subagents"], undefined);
-  assert.equal(
+  assert.ok(packageJson.files.includes("pi-subagents"));
+  assert.equal(packageJson.dependencies["@tintinweb/pi-subagents"], "file:./pi-subagents");
+  assert.ok(
     packageJson.pi.extensions.includes("./extensions/subagents.ts"),
-    false,
-    "the bundle must not default-load the disabled subagents wrapper",
+    "the bundle must default-load the locally maintained subagents wrapper",
   );
+
+  const home = await mkdtemp(join(tmpdir(), "my-pi-subagents-wrapper-load-"));
+  const result = spawnSync(
+    "pi",
+    ["--no-extensions", "-e", join(repositoryRoot, "extensions", "subagents.ts"), "--mode", "rpc"],
+    {
+      encoding: "utf8",
+      timeout: 60_000,
+      env: {
+        ...process.env,
+        HOME: home,
+        XDG_CONFIG_HOME: join(home, ".config"),
+        PI_CODING_AGENT_DIR: join(home, ".pi-agent"),
+        PI_OFFLINE: "1",
+      },
+    },
+  );
+
+  assert.equal(result.status, 0, `${result.stdout}\n${result.stderr}`);
+  assert.doesNotMatch(`${result.stdout}\n${result.stderr}`, /Failed to load extension/u);
 });
 
 test("all package extensions load together without global registration conflicts", { skip: !hasPi }, async () => {
@@ -117,6 +136,9 @@ test("all package extensions load together without global registration conflicts
 	assert.equal(permissionConfig.permission.ssh_connect, "ask", "SSH connection must enter the permission gate");
 	assert.equal(permissionConfig.permission.ssh_cd, "ask", "remote workspace changes must enter the permission gate");
 	assert.deepEqual(permissionConfig.authorizerChain, ["auto-review"], "SSH connection asks must reach AutoReview");
+	assert.equal(permissionConfig.permission.Agent, "allow", "launching a subagent is side-effect free; child actions stay gated");
+	assert.equal(permissionConfig.permission.get_subagent_result, "allow");
+	assert.equal(permissionConfig.permission.steer_subagent, "allow");
 	assert.equal(hardGuardConfig.permission.path, undefined, "sensitive paths must not be hard-denied by default");
 	assert.equal(hardGuardConfig.permission.bash["rm -rf /"], "deny");
 	assert.equal(
@@ -149,8 +171,18 @@ test("all package extensions load together without global registration conflicts
 		"the packed bundle must include the locally maintained notification source",
 	);
 	assert.equal(packageJson.dependencies["@ogulcancelik/pi-minimal-footer"], "file:./pi-minimal-footer");
-	assert.equal(packageJson.dependencies["@tintinweb/pi-subagents"], undefined);
-	assert.equal(packageJson.pi.extensions.includes("./extensions/subagents.ts"), false);
+	assert.equal(packageJson.dependencies["@tintinweb/pi-subagents"], "file:./pi-subagents");
+	assert.ok(packageJson.pi.extensions.includes("./extensions/subagents.ts"));
+	assert.ok(
+		packageJson.pi.extensions.indexOf("./extensions/permission-system.ts") <
+			packageJson.pi.extensions.indexOf("./extensions/subagents.ts"),
+		"the permission service must load before the subagents wrapper injects it as a mandatory child extension",
+	);
+	assert.ok(
+		packageJson.pi.extensions.indexOf("./extensions/subagents.ts") <
+			packageJson.pi.extensions.indexOf("./pi-tool-search/extensions/index.ts"),
+		"the subagent orchestration tools must register before Tool Search builds its catalog",
+	);
 	assert.ok(
 		packageJson.pi.extensions.includes("./pi-hermes-memory/src/index.ts"),
 		"the bundle must load the locally maintained Hermes memory extension",