diff --git a/src/main/services/team/TeamProvisioningService.ts b/src/main/services/team/TeamProvisioningService.ts
index 5dbfec0a..897fdc5b 100644
--- a/src/main/services/team/TeamProvisioningService.ts
+++ b/src/main/services/team/TeamProvisioningService.ts
@@ -3815,6 +3815,36 @@ export class TeamProvisioningService {
     }
   }
 
+  private resumeTaskActivityIntervalsForAliveMembers(
+    teamName: string,
+    memberNames: readonly string[],
+    at: string
+  ): void {
+    if (memberNames.length === 0) return;
+    const applied = this.getMemberTaskActivityResumeAppliedSet(teamName);
+    const pendingNames: string[] = [];
+    const pendingKeys: string[] = [];
+    const seen = new Set<string>();
+    for (const name of memberNames) {
+      const memberKey = this.normalizeMemberKeyForTaskActivity(name);
+      if (!memberKey || applied.has(memberKey) || seen.has(memberKey)) continue;
+      seen.add(memberKey);
+      pendingNames.push(name);
+      pendingKeys.push(memberKey);
+    }
+    if (pendingNames.length === 0) return;
+    const result = this.taskActivityIntervalService.resumeActiveIntervalsForMembers(
+      teamName,
+      pendingNames,
+      at
+    );
+    if (!result.failed) {
+      for (const key of pendingKeys) {
+        applied.add(key);
+      }
+    }
+  }
+
   private dropTaskActivityResumeMarkerForMember(teamName: string, memberName: string): void {
     const memberKey = this.normalizeMemberKeyForTaskActivity(memberName);
     if (!memberKey) return;
@@ -13983,13 +14013,19 @@ export class TeamProvisioningService {
           this.getOpenCodeSecondaryBootstrapPendingMemberNames(snapshot),
       });
       const runtimeObservedAt = nowIso();
+      const aliveMemberNames: string[] = [];
       for (const [memberName, entry] of Object.entries(nextStatuses)) {
         if (entry.runtimeAlive === true) {
-          this.resumeTaskActivityIntervalsForAliveMember(teamName, memberName, runtimeObservedAt);
+          aliveMemberNames.push(memberName);
         } else {
           this.dropTaskActivityResumeMarkerForMember(teamName, memberName);
         }
       }
+      this.resumeTaskActivityIntervalsForAliveMembers(
+        teamName,
+        aliveMemberNames,
+        runtimeObservedAt
+      );
       const expectedMembers = snapshot ? this.getPersistedLaunchMemberNames(snapshot) : undefined;
       const summary = expectedMembers
         ? summarizeMemberSpawnStatusRecord(expectedMembers, nextStatuses)
diff --git a/src/main/services/team/TeamTaskActivityIntervalService.ts b/src/main/services/team/TeamTaskActivityIntervalService.ts
index 00b8987b..a094ece0 100644
--- a/src/main/services/team/TeamTaskActivityIntervalService.ts
+++ b/src/main/services/team/TeamTaskActivityIntervalService.ts
@@ -321,6 +321,58 @@ function writeTaskFile(filePath: string, task: MutableTeamTask): void {
   fs.renameSync(tempPath, filePath);
 }
 
+function collectUniqueMemberKeys(memberNames: readonly string[]): string[] {
+  const seen = new Set<string>();
+  const keys: string[] = [];
+  for (const name of memberNames) {
+    const key = normalizeMemberName(name);
+    if (!key || seen.has(key)) continue;
+    seen.add(key);
+    keys.push(key);
+  }
+  return keys;
+}
+
+function applyResumeIntervalsForMember(
+  task: MutableTeamTask,
+  memberKey: string,
+  at: string
+): boolean {
+  let changed = false;
+
+  if (
+    task.status === 'in_progress' &&
+    normalizeMemberName(task.owner) === memberKey &&
+    !hasOpenWorkInterval(task)
+  ) {
+    const activeStartedAt = getActiveWorkStartedAt(task);
+    task.workIntervals = [
+      ...(Array.isArray(task.workIntervals) ? task.workIntervals : []),
+      { startedAt: resumeStartIso(activeStartedAt, at) },
+    ];
+    changed = true;
+  }
+
+  const activeReview = getActiveReviewStart(task);
+  if (
+    task.status === 'completed' &&
+    activeReview &&
+    normalizeMemberName(activeReview.reviewer) === memberKey &&
+    !hasOpenReviewInterval(task, activeReview.reviewer)
+  ) {
+    task.reviewIntervals = [
+      ...(Array.isArray(task.reviewIntervals) ? task.reviewIntervals : []),
+      {
+        reviewer: activeReview.reviewer,
+        startedAt: resumeStartIso(activeReview.startedAt, at),
+      },
+    ];
+    changed = true;
+  }
+
+  return changed;
+}
+
 export class TeamTaskActivityIntervalService {
   private mutateTeamTasks(
     teamName: string,
@@ -403,42 +455,24 @@ export class TeamTaskActivityIntervalService {
     memberName: string,
     at = new Date().toISOString()
   ): ActivityIntervalResult {
-    const memberKey = normalizeMemberName(memberName);
-    if (!memberKey) return { changedTasks: 0 };
+    return this.resumeActiveIntervalsForMembers(teamName, [memberName], at);
+  }
+
+  resumeActiveIntervalsForMembers(
+    teamName: string,
+    memberNames: readonly string[],
+    at = new Date().toISOString()
+  ): ActivityIntervalResult {
+    const memberKeys = collectUniqueMemberKeys(memberNames);
+    if (memberKeys.length === 0) return { changedTasks: 0 };
 
     return this.mutateTeamTasks(teamName, (task) => {
       let changed = false;
-
-      if (
-        task.status === 'in_progress' &&
-        normalizeMemberName(task.owner) === memberKey &&
-        !hasOpenWorkInterval(task)
-      ) {
-        const activeStartedAt = getActiveWorkStartedAt(task);
-        task.workIntervals = [
-          ...(Array.isArray(task.workIntervals) ? task.workIntervals : []),
-          { startedAt: resumeStartIso(activeStartedAt, at) },
-        ];
-        changed = true;
+      for (const memberKey of memberKeys) {
+        if (applyResumeIntervalsForMember(task, memberKey, at)) {
+          changed = true;
+        }
       }
-
-      const activeReview = getActiveReviewStart(task);
-      if (
-        task.status === 'completed' &&
-        activeReview &&
-        normalizeMemberName(activeReview.reviewer) === memberKey &&
-        !hasOpenReviewInterval(task, activeReview.reviewer)
-      ) {
-        task.reviewIntervals = [
-          ...(Array.isArray(task.reviewIntervals) ? task.reviewIntervals : []),
-          {
-            reviewer: activeReview.reviewer,
-            startedAt: resumeStartIso(activeReview.startedAt, at),
-          },
-        ];
-        changed = true;
-      }
-
       return changed;
     });
   }
diff --git a/test/main/services/team/TeamProvisioningService.test.ts b/test/main/services/team/TeamProvisioningService.test.ts
index 5413da27..da153b6b 100644
--- a/test/main/services/team/TeamProvisioningService.test.ts
+++ b/test/main/services/team/TeamProvisioningService.test.ts
@@ -2755,6 +2755,193 @@ describe('TeamProvisioningService', () => {
         resumeSpy.mockRestore();
       }
     });
+
+    it('routes alive-member batch through a single resumeActiveIntervalsForMembers call', () => {
+      const batchSpy = vi
+        .spyOn(TeamTaskActivityIntervalService.prototype, 'resumeActiveIntervalsForMembers')
+        .mockReturnValue({ changedTasks: 0 });
+      try {
+        const svc = new TeamProvisioningService();
+        const internals = svc as unknown as {
+          resumeTaskActivityIntervalsForAliveMembers: (
+            teamName: string,
+            memberNames: readonly string[],
+            at: string
+          ) => void;
+        };
+        const teamName = 'alive-members-batch-team';
+
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          ['alice', 'bob', 'carol'],
+          '2026-05-29T00:00:00.000Z'
+        );
+
+        expect(batchSpy).toHaveBeenCalledTimes(1);
+        expect(batchSpy).toHaveBeenCalledWith(
+          teamName,
+          ['alice', 'bob', 'carol'],
+          '2026-05-29T00:00:00.000Z'
+        );
+      } finally {
+        batchSpy.mockRestore();
+      }
+    });
+
+    it('skips members that are already marked applied and dedupes name aliases', () => {
+      const batchSpy = vi
+        .spyOn(TeamTaskActivityIntervalService.prototype, 'resumeActiveIntervalsForMembers')
+        .mockReturnValue({ changedTasks: 0 });
+      try {
+        const svc = new TeamProvisioningService();
+        const internals = svc as unknown as {
+          resumeTaskActivityIntervalsForAliveMembers: (
+            teamName: string,
+            memberNames: readonly string[],
+            at: string
+          ) => void;
+          resumeTaskActivityIntervalsForAliveMember: (
+            teamName: string,
+            memberName: string,
+            at: string
+          ) => void;
+        };
+        const teamName = 'alive-members-applied-team';
+
+        // Prime the applied set for 'alice' via the single-member path.
+        internals.resumeTaskActivityIntervalsForAliveMember(
+          teamName,
+          'alice',
+          '2026-05-29T00:00:00.000Z'
+        );
+        expect(batchSpy).toHaveBeenCalledTimes(1);
+        batchSpy.mockClear();
+
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          ['ALICE', 'alice', '  bob  ', 'bob', 'carol'],
+          '2026-05-29T00:00:10.000Z'
+        );
+
+        expect(batchSpy).toHaveBeenCalledTimes(1);
+        expect(batchSpy).toHaveBeenCalledWith(
+          teamName,
+          ['  bob  ', 'carol'],
+          '2026-05-29T00:00:10.000Z'
+        );
+      } finally {
+        batchSpy.mockRestore();
+      }
+    });
+
+    it('does not invoke the batch when there is no pending alive member', () => {
+      const batchSpy = vi
+        .spyOn(TeamTaskActivityIntervalService.prototype, 'resumeActiveIntervalsForMembers')
+        .mockReturnValue({ changedTasks: 0 });
+      try {
+        const svc = new TeamProvisioningService();
+        const internals = svc as unknown as {
+          resumeTaskActivityIntervalsForAliveMembers: (
+            teamName: string,
+            memberNames: readonly string[],
+            at: string
+          ) => void;
+        };
+        const teamName = 'alive-members-empty-team';
+
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          [],
+          '2026-05-29T00:00:00.000Z'
+        );
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          ['', '   '],
+          '2026-05-29T00:00:00.000Z'
+        );
+
+        expect(batchSpy).not.toHaveBeenCalled();
+      } finally {
+        batchSpy.mockRestore();
+      }
+    });
+
+    it('retries the alive-member batch when the previous batch reported failure', () => {
+      const batchSpy = vi
+        .spyOn(TeamTaskActivityIntervalService.prototype, 'resumeActiveIntervalsForMembers')
+        .mockReturnValueOnce({ changedTasks: 0, failed: true })
+        .mockReturnValueOnce({ changedTasks: 2 });
+      try {
+        const svc = new TeamProvisioningService();
+        const internals = svc as unknown as {
+          resumeTaskActivityIntervalsForAliveMembers: (
+            teamName: string,
+            memberNames: readonly string[],
+            at: string
+          ) => void;
+        };
+        const teamName = 'alive-members-retry-team';
+
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          ['alice', 'bob'],
+          '2026-05-29T00:00:00.000Z'
+        );
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          ['alice', 'bob'],
+          '2026-05-29T00:00:05.000Z'
+        );
+
+        expect(batchSpy).toHaveBeenCalledTimes(2);
+        expect(batchSpy).toHaveBeenNthCalledWith(
+          1,
+          teamName,
+          ['alice', 'bob'],
+          '2026-05-29T00:00:00.000Z'
+        );
+        expect(batchSpy).toHaveBeenNthCalledWith(
+          2,
+          teamName,
+          ['alice', 'bob'],
+          '2026-05-29T00:00:05.000Z'
+        );
+      } finally {
+        batchSpy.mockRestore();
+      }
+    });
+
+    it('does not re-invoke the batch on a subsequent call once members are applied', () => {
+      const batchSpy = vi
+        .spyOn(TeamTaskActivityIntervalService.prototype, 'resumeActiveIntervalsForMembers')
+        .mockReturnValue({ changedTasks: 0 });
+      try {
+        const svc = new TeamProvisioningService();
+        const internals = svc as unknown as {
+          resumeTaskActivityIntervalsForAliveMembers: (
+            teamName: string,
+            memberNames: readonly string[],
+            at: string
+          ) => void;
+        };
+        const teamName = 'alive-members-dedup-team';
+
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          ['alice', 'bob'],
+          '2026-05-29T00:00:00.000Z'
+        );
+        internals.resumeTaskActivityIntervalsForAliveMembers(
+          teamName,
+          ['alice', 'bob'],
+          '2026-05-29T00:00:05.000Z'
+        );
+
+        expect(batchSpy).toHaveBeenCalledTimes(1);
+      } finally {
+        batchSpy.mockRestore();
+      }
+    });
   });
 
   describe('member spawn status launch reads', () => {
diff --git a/test/main/services/team/TeamTaskActivityIntervalService.test.ts b/test/main/services/team/TeamTaskActivityIntervalService.test.ts
index aa3af821..789d4b38 100644
--- a/test/main/services/team/TeamTaskActivityIntervalService.test.ts
+++ b/test/main/services/team/TeamTaskActivityIntervalService.test.ts
@@ -811,4 +811,342 @@ describe('TeamTaskActivityIntervalService', () => {
 
     expect(result).toEqual({ changedTasks: 0, failed: true });
   });
+
+  describe('resumeActiveIntervalsForMembers (batch)', () => {
+    it('returns zero changes for an empty members list without scanning the tasks directory', () => {
+      const service = new TeamTaskActivityIntervalService();
+      const mutateSpy = vi.spyOn(
+        service as unknown as {
+          mutateTeamTasks: TeamTaskActivityIntervalService['resumeActiveIntervalsForMember'];
+        },
+        'mutateTeamTasks'
+      );
+
+      const result = service.resumeActiveIntervalsForMembers(
+        'alpha',
+        [],
+        '2026-05-08T10:20:00.000Z'
+      );
+
+      expect(result).toEqual({ changedTasks: 0 });
+      expect(mutateSpy).not.toHaveBeenCalled();
+    });
+
+    it('returns zero changes when all member names are blank', () => {
+      const service = new TeamTaskActivityIntervalService();
+      const mutateSpy = vi.spyOn(
+        service as unknown as {
+          mutateTeamTasks: TeamTaskActivityIntervalService['resumeActiveIntervalsForMember'];
+        },
+        'mutateTeamTasks'
+      );
+
+      const result = service.resumeActiveIntervalsForMembers(
+        'alpha',
+        ['', '   ', null as unknown as string],
+        '2026-05-08T10:20:00.000Z'
+      );
+
+      expect(result).toEqual({ changedTasks: 0 });
+      expect(mutateSpy).not.toHaveBeenCalled();
+    });
+
+    it('produces the same per-task result as sequential single-member calls', async () => {
+      const baseTime = '2026-05-08T10:00:00.000Z';
+      const resumeAt = '2026-05-08T10:20:00.000Z';
+
+      async function seed(teamName: string): Promise<void> {
+        await writeTask(teamName, {
+          id: 'work-bob',
+          subject: 'Bob work',
+          owner: 'bob',
+          status: 'in_progress',
+          workIntervals: [{ startedAt: baseTime, completedAt: '2026-05-08T10:05:00.000Z' }],
+          historyEvents: [],
+        });
+        await writeTask(teamName, {
+          id: 'work-tom',
+          subject: 'Tom work',
+          owner: 'tom',
+          status: 'in_progress',
+          workIntervals: [{ startedAt: baseTime, completedAt: '2026-05-08T10:05:00.000Z' }],
+          historyEvents: [],
+        });
+        await writeTask(teamName, {
+          id: 'review-task',
+          subject: 'Review',
+          owner: 'alice',
+          status: 'completed',
+          reviewIntervals: [
+            {
+              reviewer: 'bob',
+              startedAt: '2026-05-08T10:06:00.000Z',
+              completedAt: '2026-05-08T10:08:00.000Z',
+            },
+          ],
+          historyEvents: [
+            {
+              id: 'event-review-started',
+              type: 'review_started',
+              timestamp: '2026-05-08T10:06:00.000Z',
+              actor: 'bob',
+            },
+          ],
+        });
+      }
+
+      await seed('seq');
+      const seqService = new TeamTaskActivityIntervalService();
+      seqService.resumeActiveIntervalsForMember('seq', 'bob', resumeAt);
+      seqService.resumeActiveIntervalsForMember('seq', 'tom', resumeAt);
+
+      await seed('batch');
+      const batchService = new TeamTaskActivityIntervalService();
+      const batchResult = batchService.resumeActiveIntervalsForMembers(
+        'batch',
+        ['bob', 'tom'],
+        resumeAt
+      );
+
+      expect(batchResult.changedTasks).toBe(3);
+      for (const id of ['work-bob', 'work-tom', 'review-task']) {
+        const seqTask = await readTask('seq', id);
+        const batchTask = await readTask('batch', id);
+        expect(batchTask.workIntervals).toEqual(seqTask.workIntervals);
+        expect(batchTask.reviewIntervals).toEqual(seqTask.reviewIntervals);
+        expect(batchTask.status).toBe(seqTask.status);
+      }
+    });
+
+    it('acquires the team lock once regardless of the number of members', async () => {
+      await writeTask('alpha', {
+        id: 'task-bob',
+        subject: 'Bob',
+        owner: 'bob',
+        status: 'in_progress',
+        workIntervals: [],
+        historyEvents: [
+          {
+            id: 'event-work-started-bob',
+            type: 'status_changed',
+            from: 'pending',
+            to: 'in_progress',
+            timestamp: '2026-05-08T10:00:00.000Z',
+            actor: 'bob',
+          },
+        ],
+      });
+      await writeTask('alpha', {
+        id: 'task-tom',
+        subject: 'Tom',
+        owner: 'tom',
+        status: 'in_progress',
+        workIntervals: [],
+        historyEvents: [
+          {
+            id: 'event-work-started-tom',
+            type: 'status_changed',
+            from: 'pending',
+            to: 'in_progress',
+            timestamp: '2026-05-08T10:01:00.000Z',
+            actor: 'tom',
+          },
+        ],
+      });
+      await writeTask('alpha', {
+        id: 'task-zoe',
+        subject: 'Zoe',
+        owner: 'zoe',
+        status: 'in_progress',
+        workIntervals: [],
+        historyEvents: [
+          {
+            id: 'event-work-started-zoe',
+            type: 'status_changed',
+            from: 'pending',
+            to: 'in_progress',
+            timestamp: '2026-05-08T10:02:00.000Z',
+            actor: 'zoe',
+          },
+        ],
+      });
+
+      const service = new TeamTaskActivityIntervalService();
+      const mutateSpy = vi.spyOn(
+        service as unknown as {
+          mutateTeamTasks: TeamTaskActivityIntervalService['resumeActiveIntervalsForMember'];
+        },
+        'mutateTeamTasks'
+      );
+
+      const result = service.resumeActiveIntervalsForMembers(
+        'alpha',
+        ['bob', 'tom', 'zoe'],
+        '2026-05-08T10:20:00.000Z'
+      );
+
+      expect(mutateSpy).toHaveBeenCalledTimes(1);
+      expect(result.changedTasks).toBe(3);
+    });
+
+    it('deduplicates member names that normalize to the same key', async () => {
+      await writeTask('alpha', {
+        id: 'work-task',
+        subject: 'Build',
+        owner: 'bob',
+        status: 'in_progress',
+        workIntervals: [
+          { startedAt: '2026-05-08T10:00:00.000Z', completedAt: '2026-05-08T10:05:00.000Z' },
+        ],
+        historyEvents: [],
+      });
+
+      const result = new TeamTaskActivityIntervalService().resumeActiveIntervalsForMembers(
+        'alpha',
+        ['bob', 'BOB', '  bob  '],
+        '2026-05-08T10:20:00.000Z'
+      );
+      const task = await readTask('alpha', 'work-task');
+
+      expect(result.changedTasks).toBe(1);
+      expect(task.workIntervals).toEqual([
+        { startedAt: '2026-05-08T10:00:00.000Z', completedAt: '2026-05-08T10:05:00.000Z' },
+        { startedAt: '2026-05-08T10:20:00.000Z' },
+      ]);
+    });
+
+    it('does not write task files when no listed member matches any task', async () => {
+      await writeTask('alpha', {
+        id: 'work-bob',
+        subject: 'Bob work',
+        owner: 'bob',
+        status: 'in_progress',
+        workIntervals: [{ startedAt: '2026-05-08T10:00:00.000Z' }],
+        historyEvents: [],
+      });
+
+      const taskPath = path.join(tempDir, 'tasks', 'alpha', 'work-bob.json');
+      const beforeMtime = (await fs.stat(taskPath)).mtimeMs;
+      const beforeContents = await fs.readFile(taskPath, 'utf8');
+
+      const result = new TeamTaskActivityIntervalService().resumeActiveIntervalsForMembers(
+        'alpha',
+        ['no-such-member', 'another-ghost'],
+        '2026-05-08T10:20:00.000Z'
+      );
+
+      const afterMtime = (await fs.stat(taskPath)).mtimeMs;
+      const afterContents = await fs.readFile(taskPath, 'utf8');
+
+      expect(result.changedTasks).toBe(0);
+      expect(afterMtime).toBe(beforeMtime);
+      expect(afterContents).toBe(beforeContents);
+    });
+
+    it('opens at most one work interval per task even when the owner is listed twice', async () => {
+      await writeTask('alpha', {
+        id: 'work-task',
+        subject: 'Build',
+        owner: 'bob',
+        status: 'in_progress',
+        workIntervals: [
+          { startedAt: '2026-05-08T10:00:00.000Z', completedAt: '2026-05-08T10:05:00.000Z' },
+        ],
+        historyEvents: [],
+      });
+
+      const result = new TeamTaskActivityIntervalService().resumeActiveIntervalsForMembers(
+        'alpha',
+        ['bob', 'bob'],
+        '2026-05-08T10:20:00.000Z'
+      );
+      const task = await readTask('alpha', 'work-task');
+
+      expect(result.changedTasks).toBe(1);
+      expect(task.workIntervals).toEqual([
+        { startedAt: '2026-05-08T10:00:00.000Z', completedAt: '2026-05-08T10:05:00.000Z' },
+        { startedAt: '2026-05-08T10:20:00.000Z' },
+      ]);
+    });
+
+    it('returns 0 changes for a non-existent team directory', async () => {
+      const result = new TeamTaskActivityIntervalService().resumeActiveIntervalsForMembers(
+        'ghost-team',
+        ['bob'],
+        '2026-05-08T10:20:00.000Z'
+      );
+
+      expect(result).toEqual({ changedTasks: 0 });
+    });
+
+    it('reports failure when task directory cannot be scanned', async () => {
+      await fs.mkdir(path.join(tempDir, 'tasks'), { recursive: true });
+      await fs.writeFile(path.join(tempDir, 'tasks', 'alpha'), 'not a directory', 'utf8');
+
+      const result = new TeamTaskActivityIntervalService().resumeActiveIntervalsForMembers(
+        'alpha',
+        ['bob'],
+        '2026-05-08T10:20:00.000Z'
+      );
+
+      expect(result).toEqual({ changedTasks: 0, failed: true });
+    });
+
+    it('skips malformed task JSON files and still applies updates to valid ones', async () => {
+      await writeTask('alpha', {
+        id: 'good-task',
+        subject: 'Build',
+        owner: 'bob',
+        status: 'in_progress',
+        workIntervals: [
+          { startedAt: '2026-05-08T10:00:00.000Z', completedAt: '2026-05-08T10:05:00.000Z' },
+        ],
+        historyEvents: [],
+      });
+      await fs.writeFile(
+        path.join(tempDir, 'tasks', 'alpha', 'broken-task.json'),
+        '{ this is not valid json',
+        'utf8'
+      );
+
+      const result = new TeamTaskActivityIntervalService().resumeActiveIntervalsForMembers(
+        'alpha',
+        ['bob'],
+        '2026-05-08T10:20:00.000Z'
+      );
+      const goodTask = await readTask('alpha', 'good-task');
+
+      expect(result.changedTasks).toBe(1);
+      expect(goodTask.workIntervals).toEqual([
+        { startedAt: '2026-05-08T10:00:00.000Z', completedAt: '2026-05-08T10:05:00.000Z' },
+        { startedAt: '2026-05-08T10:20:00.000Z' },
+      ]);
+    });
+
+    it('routes single-member resumeActiveIntervalsForMember through the batch implementation', async () => {
+      await writeTask('alpha', {
+        id: 'work-task',
+        subject: 'Build',
+        owner: 'bob',
+        status: 'in_progress',
+        workIntervals: [
+          { startedAt: '2026-05-08T10:00:00.000Z', completedAt: '2026-05-08T10:05:00.000Z' },
+        ],
+        historyEvents: [],
+      });
+
+      const service = new TeamTaskActivityIntervalService();
+      const batchSpy = vi.spyOn(service, 'resumeActiveIntervalsForMembers');
+
+      const result = service.resumeActiveIntervalsForMember(
+        'alpha',
+        'bob',
+        '2026-05-08T10:20:00.000Z'
+      );
+
+      expect(batchSpy).toHaveBeenCalledTimes(1);
+      expect(batchSpy).toHaveBeenCalledWith('alpha', ['bob'], '2026-05-08T10:20:00.000Z');
+      expect(result.changedTasks).toBe(1);
+    });
+  });
 });