diff --git a/lib/projects.ts b/lib/projects.ts
index cb9c1ca..4215e40 100644
--- a/lib/projects.ts
+++ b/lib/projects.ts
@@ -230,6 +230,7 @@ export async function activateWorker(
 /**
  * Mark a worker as inactive after task completion.
  * Preserves sessions map and tier for reuse via updateWorker's spread.
+ * Clears startTime to prevent stale timestamps on inactive workers.
  */
 export async function deactivateWorker(
   workspaceDir: string,
@@ -239,6 +240,7 @@ export async function deactivateWorker(
   return updateWorker(workspaceDir, groupId, role, {
     active: false,
     issueId: null,
+    startTime: null,
   });
 }
 
diff --git a/lib/services/health.ts b/lib/services/health.ts
index 053bd82..031bbdb 100644
--- a/lib/services/health.ts
+++ b/lib/services/health.ts
@@ -74,7 +74,7 @@ export async function checkWorkerHealth(opts: {
       fixed: false,
     };
     if (autoFix) {
-      await updateWorker(workspaceDir, groupId, role, { active: false, issueId: null });
+      await updateWorker(workspaceDir, groupId, role, { active: false, issueId: null, startTime: null });
       fix.fixed = true;
     }
     fixes.push(fix);
@@ -95,7 +95,7 @@ export async function checkWorkerHealth(opts: {
       await revertIssueLabel(fix);
       const sessions = { ...worker.sessions };
       if (worker.tier) sessions[worker.tier] = null;
-      await updateWorker(workspaceDir, groupId, role, { active: false, issueId: null, sessions });
+      await updateWorker(workspaceDir, groupId, role, { active: false, issueId: null, startTime: null, sessions });
       fix.fixed = true;
     }
     fixes.push(fix);
@@ -135,7 +135,7 @@ export async function checkWorkerHealth(opts: {
       };
       if (autoFix) {
         await revertIssueLabel(fix);
-        await updateWorker(workspaceDir, groupId, role, { active: false, issueId: null });
+        await updateWorker(workspaceDir, groupId, role, { active: false, issueId: null, startTime: null });
         fix.fixed = true;
       }
       fixes.push(fix);