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。

Generated with [Devin](https://devin.ai)

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

pi-hermes-memory/src/handlers/background-review.ts

@@ -17,6 +17,7 @@ import { MemoryStore } from "../store/memory-store.js";
 import { DatabaseManager } from "../store/db.js";
 import type { MemoryConfig } from "../types.js";
 import type { EnsureMemoryReady } from "../memory-initialization.js";
+import { isSubagentSession } from "../subagent-mode.js";
 import { applyRecentMessageLimit, collectMessageParts } from "./message-parts.js";
 import { execChildPrompt, resolveChildPiModel } from "./pi-child-process.js";
 import { REVIEW_COMPLETION_TIMEOUT_MS, runDirectMemoryCompletion, usesDirectTransport, type DirectReviewResult } from "./review-memory-ops.js";
@@ -196,6 +197,7 @@ export function setupBackgroundReview(
   });
 
   pi.on("turn_end", async (event, ctx) => {
+    if (isSubagentSession(ctx)) return;
     turnsSinceReview++;
 
     if (!config.reviewEnabled) return;

pi-hermes-memory/src/handlers/correction-detector.ts

@@ -23,6 +23,7 @@ import {
 } from "../constants.js";
 import type { MemoryConfig } from "../types.js";
 import type { EnsureMemoryReady } from "../memory-initialization.js";
+import { isSubagentSession } from "../subagent-mode.js";
 import { getMessageText } from "../types.js";
 import { execChildPrompt, resolveChildPiModel } from "./pi-child-process.js";
 import { resolveProjectName, resolveProjectStore, type ProjectNameRef, type ProjectStoreRef } from "../project-context.js";
@@ -151,6 +152,7 @@ export function setupCorrectionDetector(
 
   // Trigger on turn_end (we need full context: user correction + what agent said)
   pi.on("turn_end", async (event, ctx) => {
+    if (isSubagentSession(ctx)) return;
     if (!pendingCorrection) {
       turnsSinceLastCorrection++;
       return;

pi-hermes-memory/src/handlers/session-flush.ts

@@ -37,6 +37,7 @@ import {
 import type { MemoryConfig } from "../types.js";
 import type { EnsureMemoryReady } from "../memory-initialization.js";
 import { measureLifecycle } from "../lifecycle-timing.js";
+import { isSubagentSession } from "../subagent-mode.js";
 import { collectMessageParts } from "./message-parts.js";
 import { execChildPrompt, resolveChildPiModel } from "./pi-child-process.js";
 import { runDirectMemoryCompletion, usesDirectTransport } from "./review-memory-ops.js";
@@ -167,6 +168,7 @@ export function setupSessionFlush(
     kind: FlushKind,
   ): Promise<void> {
     try {
+      if (isSubagentSession(ctx)) return;
       if (userTurnCount < config.flushMinTurns) return;
 
       let entries;

pi-hermes-memory/src/index.ts

@@ -61,6 +61,7 @@ import { AGENT_ROOT } from "./paths.js";
 import { isDatabaseMigrationPending } from "./extension-root-migration.js";
 import { measureLifecycle, measureLifecycleSync } from "./lifecycle-timing.js";
 import { createMemoryInitializer, withMemoryInitialization, type EnsureMemoryReady } from "./memory-initialization.js";
+import { isSubagentSession, markSubagentSession, markSubagentSessionFromPrompt } from "./subagent-mode.js";
 
 export function resolveProjectSkillDiscovery(
   skillStore: SkillStore,
@@ -195,8 +196,12 @@ export default function (pi: ExtensionAPI) {
 
   const initialization = createMemoryInitializer(async (ctx) => {
     const timingPrefix = lazy ? "memory-init" : "session-start";
-    if (lazy) migrateLegacyProjectMemoryDirs(agentRoot, config.projectsMemoryDir);
-    if (!persistenceInitialized) {
+    // Subagent sessions are read-only: skip the write side of initialization
+    // (legacy-dir migration, markdown↔SQLite sync, pruning, backfill) while
+    // still loading the store so memory_search/session_search keep working.
+    const subagent = isSubagentSession(ctx);
+    if (lazy && !subagent) migrateLegacyProjectMemoryDirs(agentRoot, config.projectsMemoryDir);
+    if (!persistenceInitialized && !subagent) {
       try {
         await measureLifecycle(`${timingPrefix}.persistence-sync`, async () => {
           // Startup reconciles the global files plus the current project only:
@@ -290,18 +295,25 @@ export default function (pi: ExtensionAPI) {
   // Skills and pinned instructions must be available even without a lookup.
   pi.on("session_start", async (_event, ctx) => {
     sessionContext = ctx;
+    // session_start runs before before_agent_start; a child's rendered prompt
+    // leads with the <active_agent> tag, so detect it here early enough to
+    // skip the session_start writes below.
+    markSubagentSessionFromPrompt(ctx.getSystemPrompt?.() ?? "", ctx);
     // Pinned directives must not depend on migration/SQLite being healthy.
     if (standingStore) await standingStore.load();
     if (!lazy) await ensureMemoryReady(ctx);
     refreshSkillProjectContext(ctx.cwd);
-    await skillStore.migrateLegacySkills();
-    await skillStore.ensureDiscoveredRoots();
+    if (!isSubagentSession(ctx)) {
+      await skillStore.migrateLegacySkills();
+      await skillStore.ensureDiscoveredRoots();
+    }
   });
 
   registerProjectSkillDiscoveryHandler(pi, skillStore, config.projectsMemoryDir);
 
   // ── 2. Inject memory policy by default; legacy mode keeps full frozen memory blocks ──
-  pi.on("before_agent_start", async (event, _ctx) => {
+  pi.on("before_agent_start", async (event, ctx) => {
+    markSubagentSession(event, ctx);
     const promptContext = await buildPromptContext(config, store, projectStoreRef(), projectNameRef(), standingStore);
     if (!promptContext) return;
 
@@ -400,6 +412,7 @@ export default function (pi: ExtensionAPI) {
 
   // ── 10. Live session indexing ──
   pi.on("message_end", async (_event, ctx) => {
+    if (isSubagentSession(ctx)) return;
     // Cold lazy sessions remain in Pi's JSONL files and are backfilled on use.
     if (lazy && !initialization.isReady()) return;
     scheduleLiveSessionIndex(dbManager, ctx.sessionManager, {
@@ -432,6 +445,7 @@ export default function (pi: ExtensionAPI) {
       return;
     }
     try {
+      if (isSubagentSession(ctx)) return;
       measureLifecycleSync("shutdown.active-index", () => {
         const sessionFile = ctx.sessionManager.getSessionFile();
         if (sessionFile && fs.existsSync(sessionFile)) {

pi-hermes-memory/src/subagent-mode.ts

@@ -0,0 +1,58 @@
+/**
+ * subagent-mode.ts — subagent sessions are read-only for memory and skill
+ * writes. All automatic write-related work (background review, correction
+ * detection, session flushes, session indexing) is skipped as well.
+ *
+ * A child session is identified by the `<active_agent name="..."/>` identity
+ * tag that pi-subagents stamps into every child prompt
+ * (permission-system-bridge.ts): the tag arrives via
+ * `systemPromptOptions.customPrompt`. The tag is only trusted on that field —
+ * never in the rendered system prompt, which a main session can legitimately
+ * contain through project docs.
+ *
+ * Membership is tracked per session by its sessionManager identity: the same
+ * process hosts the parent and its children concurrently, so a global boolean
+ * would let a child's turn flip the parent's session into read-only mid-turn.
+ */
+import type { BeforeAgentStartEvent, ExtensionContext } from "@earendil-works/pi-coding-agent";
+
+/** pi-subagents `<active_agent name="X"/>` identity tag contract. */
+const ACTIVE_AGENT_TAG = /<active_agent\s+name=["'][^"']+["'][^>]*>/i;
+const LEADING_ACTIVE_AGENT_TAG = /^\s*<active_agent\s+name=["'][^"']+["'][^>]*>/i;
+
+export const SUBAGENT_WRITE_DISABLED_MESSAGE =
+  "Memory and skill writes are disabled in subagent sessions; include this in your final report so the delegating agent can decide.";
+
+const subagentSessionManagers = new WeakSet<object>();
+
+/** Same regex as the pi-subagents `<active_agent>` contract, applied only to customPrompt. */
+export function isSubagentCustomPrompt(customPrompt: string | undefined | null): boolean {
+  return typeof customPrompt === "string" && ACTIVE_AGENT_TAG.test(customPrompt);
+}
+
+/**
+ * before_agent_start hook: authoritative detection via the event's
+ * systemPromptOptions.customPrompt.
+ */
+export function markSubagentSession(event: BeforeAgentStartEvent, ctx: ExtensionContext): void {
+  if (isSubagentCustomPrompt(event.systemPromptOptions?.customPrompt)) {
+    subagentSessionManagers.add(ctx.sessionManager);
+  }
+}
+
+/**
+ * session_start runs before before_agent_start; detect tag-leading prompts
+ * early so session_start writes (skill migration, root setup) can be skipped.
+ * A main prompt cannot lead with the tag — without customPrompt the rendered
+ * prompt always opens with the base preamble.
+ */
+export function markSubagentSessionFromPrompt(systemPrompt: string, ctx: ExtensionContext): void {
+  if (LEADING_ACTIVE_AGENT_TAG.test(systemPrompt)) {
+    subagentSessionManagers.add(ctx.sessionManager);
+  }
+}
+
+export function isSubagentSession(ctx: unknown): boolean {
+  const sm = (ctx as { sessionManager?: unknown } | undefined | null)?.sessionManager;
+  return typeof sm === "object" && sm !== null && subagentSessionManagers.has(sm);
+}

pi-hermes-memory/src/tools/memory-tool.ts

@@ -25,6 +25,7 @@ import type { MemoryCategory, MemoryResult } from "../types.js";
 import { normalizeMemoryLookupText } from "../store/memory-lookup.js";
 import { createSharedToolResultRenderer } from "./shared-output-view.js";
 import { memoryResultView } from "./tool-result-views.js";
+import { isSubagentSession, SUBAGENT_WRITE_DISABLED_MESSAGE } from "../subagent-mode.js";
 
 function appendSyncWarning(result: MemoryResult, warning: string): MemoryResult {
   const warnings = [...(((result as any).warnings ?? []) as string[]), warning];
@@ -425,7 +426,13 @@ This action-specific tool accepts only the parameters listed in its schema.`;
       ],
       renderResult: createSharedToolResultRenderer(memoryResultView),
       parameters,
-      async execute(_toolCallId, params, signal, _onUpdate, ctx?: { cwd?: string }) {
+      async execute(_toolCallId, params, signal, _onUpdate, ctx?: { cwd?: string; sessionManager?: object }) {
+        if (isSubagentSession(ctx)) {
+          return {
+            content: [{ type: "text" as const, text: SUBAGENT_WRITE_DISABLED_MESSAGE }],
+            details: { success: false, error: SUBAGENT_WRITE_DISABLED_MESSAGE },
+          };
+        }
         if (bindProjectFromCwd && ctx?.cwd) {
           await bindProjectFromCwd(ctx.cwd);
         }

pi-hermes-memory/src/tools/skill-tool.ts

@@ -10,6 +10,7 @@ import { SkillStore } from "../store/skill-store.js";
 import { SKILL_TOOL_DESCRIPTION } from "../constants.js";
 import { createSharedToolResultRenderer } from "./shared-output-view.js";
 import { skillResultView } from "./tool-result-views.js";
+import { isSubagentSession, SUBAGENT_WRITE_DISABLED_MESSAGE } from "../subagent-mode.js";
 
 function normalizeTextList(value: unknown): string[] {
   if (!Array.isArray(value)) return [];
@@ -90,6 +91,13 @@ const SKILL_TOOL_PARAMETERS = Type.Object({
 export const SKILL_MANAGE_TOOL_NAME = "skill_manage";
 
 export function registerSkillTool(pi: ExtensionAPI, store: SkillStore): void {
+  if (typeof pi.on === "function") {
+    pi.on("tool_result", (event) => {
+      if (event.toolName !== SKILL_MANAGE_TOOL_NAME) return;
+      const details = event.details as { success?: unknown } | undefined;
+      if (details?.success === false) return { isError: true };
+    });
+  }
   pi.registerTool({
     name: SKILL_MANAGE_TOOL_NAME,
     label: "Skill Manager",
@@ -108,6 +116,12 @@ export function registerSkillTool(pi: ExtensionAPI, store: SkillStore): void {
     renderResult: createSharedToolResultRenderer(skillResultView),
     parameters: SKILL_TOOL_PARAMETERS,
     async execute(toolCallId, params, signal, onUpdate, ctx) {
+      if (isSubagentSession(ctx)) {
+        return {
+          content: [{ type: "text", text: SUBAGENT_WRITE_DISABLED_MESSAGE }],
+          details: { success: false, error: SUBAGENT_WRITE_DISABLED_MESSAGE },
+        };
+      }
       const skillParams = params as {
         action: "create" | "view" | "patch" | "update" | "edit" | "delete";
         name?: string;