diff --git a/src/agents/subagent-registry.persistence.resume.test.ts b/src/agents/subagent-registry.persistence.resume.test.ts
index f789c815a79..f5a3b89d0bd 100644
--- a/src/agents/subagent-registry.persistence.resume.test.ts
+++ b/src/agents/subagent-registry.persistence.resume.test.ts
@@ -8,6 +8,10 @@ import {
   drainSessionStoreLockQueuesForTest,
 } from "../config/sessions/store.js";
 import { captureEnv } from "../test-utils/env.js";
+import {
+  createSubagentRegistryTestDeps,
+  writeSubagentSessionEntry,
+} from "./subagent-registry.persistence.test-support.js";
 
 const hoisted = vi.hoisted(() => ({
   announceSpy: vi.fn(async () => true),
@@ -71,22 +75,6 @@ describe("subagent registry persistence resume", () => {
   const envSnapshot = captureEnv(["OPENCLAW_STATE_DIR"]);
   let tempStateDir: string | null = null;
 
-  const resolveSessionStorePath = (stateDir: string, agentId: string) =>
-    path.join(stateDir, "agents", agentId, "sessions", "sessions.json");
-
-  const readSessionStore = async (storePath: string) => {
-    try {
-      const raw = await fs.readFile(storePath, "utf8");
-      const parsed = JSON.parse(raw) as unknown;
-      if (parsed && typeof parsed === "object" && !Array.isArray(parsed)) {
-        return parsed as Record<string, Record<string, unknown>>;
-      }
-    } catch {
-      // ignore
-    }
-    return {} as Record<string, Record<string, unknown>>;
-  };
-
   const writeChildSessionEntry = async (params: {
     sessionKey: string;
     sessionId?: string;
@@ -95,16 +83,14 @@ describe("subagent registry persistence resume", () => {
     if (!tempStateDir) {
       throw new Error("tempStateDir not initialized");
     }
-    const storePath = resolveSessionStorePath(tempStateDir, "main");
-    const store = await readSessionStore(storePath);
-    store[params.sessionKey] = {
-      ...store[params.sessionKey],
-      sessionId: params.sessionId ?? `sess-${Date.now()}`,
-      updatedAt: params.updatedAt ?? Date.now(),
-    };
-    await fs.mkdir(path.dirname(storePath), { recursive: true });
-    await fs.writeFile(storePath, `${JSON.stringify(store)}\n`, "utf8");
-    return storePath;
+    return await writeSubagentSessionEntry({
+      stateDir: tempStateDir,
+      agentId: "main",
+      sessionKey: params.sessionKey,
+      sessionId: params.sessionId,
+      updatedAt: params.updatedAt,
+      defaultSessionId: `sess-${Date.now()}`,
+    });
   };
 
   const flushQueuedRegistryWork = async () => {
@@ -129,19 +115,10 @@ describe("subagent registry persistence resume", () => {
       endedAt: 222,
     });
     mod.__testing.setDepsForTest({
-      callGateway: vi.mocked(callGatewayModule.callGateway),
-      cleanupBrowserSessionsForLifecycleEnd: vi.fn(async () => {}),
-      captureSubagentCompletionReply: vi.fn(async () => undefined),
-      ensureContextEnginesInitialized: vi.fn(),
-      ensureRuntimePluginsLoaded: vi.fn(),
-      loadConfig: vi.fn(() => ({})),
-      resolveAgentTimeoutMs: vi.fn(() => 100),
-      resolveContextEngine: vi.fn(async () => ({
-        info: { id: "test", name: "Test", version: "0.0.1" },
-        ingest: vi.fn(async () => ({ ingested: false })),
-        assemble: vi.fn(async ({ messages }) => ({ messages, estimatedTokens: 0 })),
-        compact: vi.fn(async () => ({ ok: false, compacted: false })),
-      })),
+      ...createSubagentRegistryTestDeps({
+        callGateway: vi.mocked(callGatewayModule.callGateway),
+        captureSubagentCompletionReply: vi.fn(async () => undefined),
+      }),
     });
     mod.resetSubagentRegistryForTests({ persist: false });
     vi.mocked(agentEventsModule.onAgentEvent).mockReset();
diff --git a/src/agents/subagent-registry.persistence.test-support.ts b/src/agents/subagent-registry.persistence.test-support.ts
new file mode 100644
index 00000000000..035d4f4e7cc
--- /dev/null
+++ b/src/agents/subagent-registry.persistence.test-support.ts
@@ -0,0 +1,74 @@
+import fs from "node:fs/promises";
+import path from "node:path";
+import { vi } from "vitest";
+
+type SessionStore = Record<string, Record<string, unknown>>;
+
+export function resolveSubagentSessionStorePath(stateDir: string, agentId: string): string {
+  return path.join(stateDir, "agents", agentId, "sessions", "sessions.json");
+}
+
+export async function readSubagentSessionStore(storePath: string): Promise<SessionStore> {
+  try {
+    const raw = await fs.readFile(storePath, "utf8");
+    const parsed = JSON.parse(raw) as unknown;
+    if (parsed && typeof parsed === "object" && !Array.isArray(parsed)) {
+      return parsed as SessionStore;
+    }
+  } catch {
+    // ignore
+  }
+  return {};
+}
+
+export async function writeSubagentSessionEntry(params: {
+  stateDir: string;
+  sessionKey: string;
+  sessionId?: string;
+  updatedAt?: number;
+  agentId: string;
+  defaultSessionId: string;
+}): Promise<string> {
+  const storePath = resolveSubagentSessionStorePath(params.stateDir, params.agentId);
+  const store = await readSubagentSessionStore(storePath);
+  store[params.sessionKey] = {
+    ...store[params.sessionKey],
+    sessionId: params.sessionId ?? params.defaultSessionId,
+    updatedAt: params.updatedAt ?? Date.now(),
+  };
+  await fs.mkdir(path.dirname(storePath), { recursive: true });
+  await fs.writeFile(storePath, `${JSON.stringify(store)}\n`, "utf8");
+  return storePath;
+}
+
+export async function removeSubagentSessionEntry(params: {
+  stateDir: string;
+  sessionKey: string;
+  agentId: string;
+}): Promise<string> {
+  const storePath = resolveSubagentSessionStorePath(params.stateDir, params.agentId);
+  const store = await readSubagentSessionStore(storePath);
+  delete store[params.sessionKey];
+  await fs.mkdir(path.dirname(storePath), { recursive: true });
+  await fs.writeFile(storePath, `${JSON.stringify(store)}\n`, "utf8");
+  return storePath;
+}
+
+export function createSubagentRegistryTestDeps(
+  extra: Record<string, unknown> = {},
+): Record<string, unknown> {
+  return {
+    cleanupBrowserSessionsForLifecycleEnd: vi.fn(async () => {}),
+    ensureContextEnginesInitialized: vi.fn(),
+    ensureRuntimePluginsLoaded: vi.fn(),
+    loadConfig: vi.fn(() => ({})),
+    resolveAgentTimeoutMs: vi.fn(() => 100),
+    resolveContextEngine: vi.fn(async () => ({
+      info: { id: "test", name: "Test", version: "0.0.1" },
+      ingest: vi.fn(async () => ({ ingested: false })),
+      assemble: vi.fn(async ({ messages }) => ({ messages, estimatedTokens: 0 })),
+      compact: vi.fn(async () => ({ ok: false, compacted: false })),
+    })),
+    ...extra,
+  };
+}
diff --git a/src/agents/subagent-registry.persistence.test.ts b/src/agents/subagent-registry.persistence.test.ts
index 05fa09316d0..d98ac955f25 100644
--- a/src/agents/subagent-registry.persistence.test.ts
+++ b/src/agents/subagent-registry.persistence.test.ts
@@ -22,6 +22,12 @@ import {
   registerSubagentRun,
   resetSubagentRegistryForTests,
 } from "./subagent-registry.js";
+import {
+  createSubagentRegistryTestDeps,
+  readSubagentSessionStore,
+  removeSubagentSessionEntry,
+  writeSubagentSessionEntry,
+} from "./subagent-registry.persistence.test-support.js";
 import {
   loadSubagentRegistryFromDisk,
   resolveSubagentRegistryPath,
@@ -47,22 +53,6 @@ describe("subagent registry persistence", () => {
     return (match?.[1] ?? "main").trim().toLowerCase() || "main";
   };
 
-  const resolveSessionStorePath = (stateDir: string, agentId: string) =>
-    path.join(stateDir, "agents", agentId, "sessions", "sessions.json");
-
-  const readSessionStore = async (storePath: string) => {
-    try {
-      const raw = await fs.readFile(storePath, "utf8");
-      const parsed = JSON.parse(raw) as unknown;
-      if (parsed && typeof parsed === "object" && !Array.isArray(parsed)) {
-        return parsed as Record<string, Record<string, unknown>>;
-      }
-    } catch {
-      // ignore
-    }
-    return {} as Record<string, Record<string, unknown>>;
-  };
-
   const writeChildSessionEntry = async (params: {
     sessionKey: string;
     sessionId?: string;
@@ -72,16 +62,14 @@ describe("subagent registry persistence", () => {
       throw new Error("tempStateDir not initialized");
     }
     const agentId = resolveAgentIdFromSessionKey(params.sessionKey);
-    const storePath = resolveSessionStorePath(tempStateDir, agentId);
-    const store = await readSessionStore(storePath);
-    store[params.sessionKey] = {
-      ...store[params.sessionKey],
-      sessionId: params.sessionId ?? `sess-${agentId}-${Date.now()}`,
-      updatedAt: params.updatedAt ?? Date.now(),
-    };
-    await fs.mkdir(path.dirname(storePath), { recursive: true });
-    await fs.writeFile(storePath, `${JSON.stringify(store)}\n`, "utf8");
-    return storePath;
+    return await writeSubagentSessionEntry({
+      stateDir: tempStateDir,
+      agentId,
+      sessionKey: params.sessionKey,
+      sessionId: params.sessionId,
+      updatedAt: params.updatedAt,
+      defaultSessionId: `sess-${agentId}-${Date.now()}`,
+    });
   };
 
   const removeChildSessionEntry = async (sessionKey: string) => {
@@ -89,12 +77,11 @@ describe("subagent registry persistence", () => {
       throw new Error("tempStateDir not initialized");
     }
     const agentId = resolveAgentIdFromSessionKey(sessionKey);
-    const storePath = resolveSessionStorePath(tempStateDir, agentId);
-    const store = await readSessionStore(storePath);
-    delete store[sessionKey];
-    await fs.mkdir(path.dirname(storePath), { recursive: true });
-    await fs.writeFile(storePath, `${JSON.stringify(store)}\n`, "utf8");
-    return storePath;
+    return await removeSubagentSessionEntry({
+      stateDir: tempStateDir,
+      agentId,
+      sessionKey,
+    });
   };
 
   const seedChildSessionsForPersistedRuns = async (persisted: Record<string, unknown>) => {
@@ -181,17 +168,7 @@ describe("subagent registry persistence", () => {
 
   beforeEach(() => {
     __testing.setDepsForTest({
-      cleanupBrowserSessionsForLifecycleEnd: vi.fn(async () => {}),
-      ensureContextEnginesInitialized: vi.fn(),
-      ensureRuntimePluginsLoaded: vi.fn(),
-      loadConfig: vi.fn(() => ({})),
-      resolveAgentTimeoutMs: vi.fn(() => 100),
-      resolveContextEngine: vi.fn(async () => ({
-        info: { id: "test", name: "Test", version: "0.0.1" },
-        ingest: vi.fn(async () => ({ ingested: false })),
-        assemble: vi.fn(async ({ messages }) => ({ messages, estimatedTokens: 0 })),
-        compact: vi.fn(async () => ({ ok: false, compacted: false })),
-      })),
+      ...createSubagentRegistryTestDeps(),
       runSubagentAnnounceFlow: announceSpy,
     });
     vi.mocked(callGateway).mockReset();
@@ -245,7 +222,7 @@ describe("subagent registry persistence", () => {
       outcome: { status: "ok" },
     } as never);
 
-    const store = await readSessionStore(storePath);
+    const store = await readSubagentSessionStore(storePath);
     const persisted = store["agent:main:subagent:timing"];
     expect(persisted?.endedAt).toBe(endedAt);
     expect(persisted?.runtimeMs).toBe(500);