perf(main): skip redundant task interval resume scans

src/main/services/team/TeamTaskActivityIntervalService.ts

@@ -18,6 +18,15 @@ interface ActivityIntervalResult {
   failed?: boolean;
 }
 
+interface TaskDirectorySignature {
+  key: string;
+}
+
+interface ResumeMembersCacheEntry {
+  memberKey: string;
+  signatureKey: string;
+}
+
 type MutableTeamTask = TeamTask & {
   reviewIntervals?: TaskReviewInterval[];
 };
@@ -322,13 +331,15 @@ function writeTaskFile(filePath: string, task: MutableTeamTask): void {
 }
 
 export class TeamTaskActivityIntervalService {
-  private mutateTeamTasks(
+  private readonly resumeMembersCache = new Map<string, ResumeMembersCacheEntry>();
+
+  private mutateTeamTasksWithLock(
     teamName: string,
-    mutate: (task: MutableTeamTask) => boolean
+    run: () => ActivityIntervalResult
   ): ActivityIntervalResult {
     const lockScope = path.join(getTeamsBasePath(), teamName, 'board-state');
     try {
-      return withFileLockSync(lockScope, () => this.mutateTeamTasksUnlocked(teamName, mutate));
+      return withFileLockSync(lockScope, run);
     } catch (error) {
       logger.warn(
         `[${teamName}] Failed to update task activity intervals: ${
@@ -339,6 +350,19 @@ export class TeamTaskActivityIntervalService {
     }
   }
 
+  private mutateTeamTasks(
+    teamName: string,
+    mutate: (task: MutableTeamTask) => boolean
+  ): ActivityIntervalResult {
+    const result = this.mutateTeamTasksWithLock(teamName, () =>
+      this.mutateTeamTasksUnlocked(teamName, mutate)
+    );
+    if (result.changedTasks > 0 || result.failed) {
+      this.resumeMembersCache.delete(teamName);
+    }
+    return result;
+  }
+
   private mutateTeamTasksUnlocked(
     teamName: string,
     mutate: (task: MutableTeamTask) => boolean
@@ -371,6 +395,38 @@ export class TeamTaskActivityIntervalService {
     return { changedTasks };
   }
 
+  private readTaskDirectorySignature(teamName: string): TaskDirectorySignature | null {
+    const tasksDir = path.join(getTasksBasePath(), teamName);
+    let entries: string[];
+    try {
+      entries = fs
+        .readdirSync(tasksDir)
+        .filter((fileName) => fileName.endsWith('.json') && !fileName.startsWith('.'))
+        .sort();
+    } catch (error) {
+      if ((error as NodeJS.ErrnoException).code === 'ENOENT') {
+        return { key: 'missing' };
+      }
+      return null;
+    }
+
+    const parts: string[] = [];
+    for (const fileName of entries) {
+      try {
+        const stat = fs.statSync(path.join(tasksDir, fileName));
+        if (!stat.isFile()) continue;
+        parts.push([fileName, stat.size, stat.mtimeMs, stat.ctimeMs].join('\0'));
+      } catch {
+        return null;
+      }
+    }
+    return { key: parts.join('\0\0') };
+  }
+
+  private makeMemberSetKey(memberKeys: ReadonlySet<string>): string {
+    return [...memberKeys].sort().join('\0');
+  }
+
   pauseActiveIntervalsForTeam(
     teamName: string,
     at = new Date().toISOString()
@@ -450,7 +506,8 @@ export class TeamTaskActivityIntervalService {
    * file-lock + read of every task file PER member PER cycle. This applies the
    * identical per-member resume logic against a member set in one locked pass, so
    * the mutations are exactly the same but the lock + reads happen once per cycle
-   * instead of once per member.
+   * instead of once per member. After a no-op pass, a task-file signature skips
+   * unchanged repeat cycles without parsing every task JSON again.
    */
   resumeActiveIntervalsForMembers(
     teamName: string,
@@ -461,8 +518,20 @@ export class TeamTaskActivityIntervalService {
       memberNames.map((name) => normalizeMemberName(name)).filter((key): key is string => !!key)
     );
     if (memberKeys.size === 0) return { changedTasks: 0 };
+    const memberKey = this.makeMemberSetKey(memberKeys);
 
-    return this.mutateTeamTasks(teamName, (task) => {
+    const result = this.mutateTeamTasksWithLock(teamName, () => {
+      const beforeSignature = this.readTaskDirectorySignature(teamName);
+      const cached = this.resumeMembersCache.get(teamName);
+      if (
+        beforeSignature &&
+        cached?.memberKey === memberKey &&
+        cached.signatureKey === beforeSignature.key
+      ) {
+        return { changedTasks: 0 };
+      }
+
+      const mutationResult = this.mutateTeamTasksUnlocked(teamName, (task) => {
         let changed = false;
 
         if (
@@ -497,6 +566,26 @@ export class TeamTaskActivityIntervalService {
 
         return changed;
       });
+
+      const nextSignature =
+        mutationResult.changedTasks > 0
+          ? this.readTaskDirectorySignature(teamName)
+          : beforeSignature;
+      if (nextSignature) {
+        this.resumeMembersCache.set(teamName, {
+          memberKey,
+          signatureKey: nextSignature.key,
+        });
+      } else {
+        this.resumeMembersCache.delete(teamName);
+      }
+      return mutationResult;
+    });
+
+    if (result.failed) {
+      this.resumeMembersCache.delete(teamName);
+    }
+    return result;
   }
 
   repairStaleIntervalsAfterCrash(

test/main/services/team/TeamTaskActivityIntervalService.test.ts

@@ -517,6 +517,84 @@ describe('TeamTaskActivityIntervalService', () => {
     expect(carolTask.workIntervals).toHaveLength(1);
   });
 
+  it('skips unchanged batched resume task reads after a no-op pass', async () => {
+    await writeTask('alpha', {
+      id: 'bob-task',
+      subject: 'Bob work',
+      owner: 'bob',
+      status: 'in_progress',
+      workIntervals: [{ startedAt: '2026-05-08T10:00:00.000Z' }],
+      historyEvents: [],
+    });
+
+    const service = new TeamTaskActivityIntervalService();
+    expect(
+      service.resumeActiveIntervalsForMembers(
+        'alpha',
+        ['bob'],
+        '2026-05-08T10:20:00.000Z'
+      ).changedTasks
+    ).toBe(0);
+
+    const jsonParseSpy = vi.spyOn(JSON, 'parse');
+    const secondResult = service.resumeActiveIntervalsForMembers(
+      'alpha',
+      ['bob'],
+      '2026-05-08T10:25:00.000Z'
+    );
+
+    expect(secondResult.changedTasks).toBe(0);
+    expect(jsonParseSpy).not.toHaveBeenCalled();
+  });
+
+  it('refreshes batched resume cache when a task file changes', async () => {
+    await writeTask('alpha', {
+      id: 'bob-task',
+      subject: 'Bob work',
+      owner: 'bob',
+      status: 'in_progress',
+      workIntervals: [{ startedAt: '2026-05-08T10:00:00.000Z' }],
+      historyEvents: [],
+    });
+
+    const service = new TeamTaskActivityIntervalService();
+    expect(
+      service.resumeActiveIntervalsForMembers(
+        'alpha',
+        ['bob'],
+        '2026-05-08T10:20:00.000Z'
+      ).changedTasks
+    ).toBe(0);
+
+    await writeTask('alpha', {
+      id: 'bob-task',
+      subject: 'Bob work',
+      owner: 'bob',
+      status: 'in_progress',
+      workIntervals: [
+        {
+          startedAt: '2026-05-08T10:00:00.000Z',
+          completedAt: '2026-05-08T10:05:00.000Z',
+        },
+      ],
+      historyEvents: [],
+      signaturePadding: 'changed-file-signature',
+    });
+
+    const result = service.resumeActiveIntervalsForMembers(
+      'alpha',
+      ['bob'],
+      '2026-05-08T10:30:00.000Z'
+    );
+    const task = await readTask('alpha', 'bob-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: '2026-05-08T10:30:00.000Z' },
+    ]);
+  });
+
   it('reopens and closes lead work intervals across activity changes', async () => {
     await writeTask('alpha', {
       id: 'lead-task',