fix(gateway): reduce session group discovery CPU overhead (#147909)

src/gateway/session-group-mutation-targets.test.ts

@@ -1,7 +1,8 @@
 import fs from "node:fs";
 import { performance } from "node:perf_hooks";
+import { DatabaseSync } from "node:sqlite";
 import { expect, test, vi } from "vitest";
-import { upsertSessionEntryCore } from "../config/sessions/session-accessor.js";
+import { loadSessionEntry, upsertSessionEntryCore } from "../config/sessions/session-accessor.js";
 import type { OpenClawConfig } from "../config/types.openclaw.js";
 import * as sqliteIntegrity from "../infra/sqlite-integrity.js";
 import * as sqliteWal from "../infra/sqlite-wal.js";
@@ -9,6 +10,7 @@ import * as agentDatabaseLeases from "../state/openclaw-agent-db-lease.js";
 import {
   closeOpenClawAgentDatabasesForTest,
   listOpenClawAgentDatabasesForTest,
+  openOpenClawAgentDatabase,
 } from "../state/openclaw-agent-db.js";
 import { closeOpenClawStateDatabaseForTest } from "../state/openclaw-state-db.js";
 import { setStateDirEnv, withStateDirEnv } from "../test-helpers/state-dir-env.js";
@@ -16,6 +18,89 @@ import { resolveSessionGroupMutationTargetsByName } from "./session-groups.js";
 
 const EXPECTED_OPEN_HANDLE_CAP = 64;
 
+test.each([false, true])(
+  "discovers current group members without decoding saved prompts (cold=%s)",
+  async (cold) => {
+    await withStateDirEnv("openclaw-session-group-metadata-", async ({ stateDir }) => {
+      setStateDirEnv(fs.realpathSync(stateDir));
+      const scopes = [
+        { agentId: "main", sessionKey: "agent:main:group-member" },
+        { agentId: "research", sessionKey: "agent:research:matrix:group:!Room:example.org" },
+      ] as const;
+      const config = {
+        agents: { list: [{ id: "main", default: true }, { id: "research" }] },
+      } satisfies OpenClawConfig;
+      const entry = {
+        sessionId: "group-member",
+        updatedAt: 1,
+        category: " Shared work ",
+        skillsSnapshot: { prompt: "unneeded-group-prompt".repeat(4096), skills: [] },
+        systemPromptReport: {
+          source: "run" as const,
+          generatedAt: 1,
+          systemPrompt: { chars: 1, projectContextChars: 0, nonProjectContextChars: 1 },
+          injectedWorkspaceFiles: [],
+          skills: { promptChars: 0, entries: [] },
+          tools: { listChars: 0, schemaChars: 0, entries: [] },
+        },
+      };
+      const parse = vi.spyOn(JSON, "parse");
+      const readTargets = () => {
+        parse.mockClear();
+        const targets = resolveSessionGroupMutationTargetsByName(config);
+        expect(
+          parse.mock.calls.filter(
+            ([json]) => json.includes('"skillsSnapshot"') || json.includes('"systemPromptReport"'),
+          ),
+        ).toEqual([]);
+        return targets;
+      };
+      try {
+        for (const scope of scopes) {
+          await upsertSessionEntryCore(scope, entry);
+        }
+        if (cold) {
+          closeOpenClawAgentDatabasesForTest();
+        }
+        expect(readTargets()).toEqual(new Map([["Shared work", scopes]]));
+        await upsertSessionEntryCore(scopes[0], { ...entry, category: "Renamed" });
+        expect(readTargets()).toEqual(
+          new Map([
+            ["Renamed", [scopes[0]]],
+            ["Shared work", [scopes[1]]],
+          ]),
+        );
+        const database = openOpenClawAgentDatabase(scopes[0]);
+        const external = new DatabaseSync(database.path);
+        try {
+          external
+            .prepare(
+              "UPDATE session_nodes SET entry_json = json_set(entry_json, '$.category', ?) WHERE session_key = ?",
+            )
+            .run("External", scopes[0].sessionKey);
+        } finally {
+          external.close();
+        }
+        expect(readTargets()).toEqual(
+          new Map([
+            ["External", [scopes[0]]],
+            ["Shared work", [scopes[1]]],
+          ]),
+        );
+        parse.mockRestore();
+        expect(loadSessionEntry(scopes[0])).toMatchObject({
+          skillsSnapshot: entry.skillsSnapshot,
+          systemPromptReport: entry.systemPromptReport,
+        });
+      } finally {
+        parse.mockRestore();
+        closeOpenClawAgentDatabasesForTest();
+        closeOpenClawStateDatabaseForTest();
+      }
+    });
+  },
+);
+
 test("discovers groups across more than the handle cap without writable database maintenance", async () => {
   await withStateDirEnv("openclaw-session-group-readonly-", async ({ stateDir }) => {
     setStateDirEnv(fs.realpathSync(stateDir));

src/gateway/session-groups.ts

@@ -450,6 +450,9 @@ export function resolveSessionGroupMutationTargetsByName(
     for (const { sessionKey, entry } of listSessionEntriesReadOnly({
       agentId: storeTarget.agentId,
       storePath: storeTarget.storePath,
+      // Membership only borrows category metadata; full reads decode every saved prompt.
+      projection: "list",
+      clone: false,
     })) {
       const groupName = normalizeOptionalString(entry.category);
       if (!groupName) {