diff --git a/src/main/worker/handlers/run-finished-handler.ts b/src/main/worker/handlers/run-finished-handler.ts
index 9ccd2707..e562e2c5 100644
--- a/src/main/worker/handlers/run-finished-handler.ts
+++ b/src/main/worker/handlers/run-finished-handler.ts
@@ -15,6 +15,10 @@ export interface RunFinishedHooks {
     | { ok: false; errorMessage: string };
 }
 
+function errorMessage(error: unknown): string {
+  return error instanceof Error ? error.message : String(error);
+}
+
 export function handleRunFinished(
   event: Extract<WorkerMessageEvent, { type: "run-finished" }>,
   deps: HandlerDeps,
@@ -37,7 +41,11 @@ export function handleRunFinished(
         }
       : event;
   if (boundaryResult && !boundaryResult.ok) {
-    deps.db.core.runs.markRunCompletionFailure(event.runId, boundaryResult.errorMessage);
+    try {
+      deps.db.core.runs.markRunCompletionFailure(event.runId, boundaryResult.errorMessage);
+    } catch (error) {
+      deps.logger.error(`[worker] markRunCompletionFailure failed for artifact boundary ${event.runId}: ${errorMessage(error)}`);
+    }
   }
   emitAndNotifyCompletion(effectiveEvent, deps, rfCtx);
   const { hadDeferredWakes } = runPostCompletionAutomation(effectiveEvent, deps, context, rfCtx);
diff --git a/src/main/worker/handlers/run-finished-helpers.ts b/src/main/worker/handlers/run-finished-helpers.ts
index 4b1e9cda..9717f8f8 100644
--- a/src/main/worker/handlers/run-finished-helpers.ts
+++ b/src/main/worker/handlers/run-finished-helpers.ts
@@ -16,6 +16,22 @@ export interface RunFinishedContext {
   runOutcome: ReturnType<HandlerDeps["db"]["core"]["runs"]["finishRun"]>;
 }
 
+function errorMessage(error: unknown): string {
+  return error instanceof Error ? error.message : String(error);
+}
+
+function runCompletionSideEffect(
+  logger: HandlerDeps["logger"],
+  label: string,
+  operation: () => void,
+): void {
+  try {
+    operation();
+  } catch (error) {
+    logger.error(`[worker] ${label} failed after run completion: ${errorMessage(error)}`);
+  }
+}
+
 export function finalizeRun(
   event: RunFinishedEvent,
   deps: HandlerDeps,
@@ -71,13 +87,15 @@ export function finalizeRun(
 
   leaseRenewalMap.delete(event.runId);
   const runOutcome = db.core.runs.finishRun({ ...event, unattributedCost });
-  db.core.activity.addActivity({
-    companyId: run.companyId,
-    actor: run.agentId,
-    action: `run.${event.status}`,
-    entityType: "run",
-    entityId: run.id,
-    detail: event.summary ?? event.errorMessage ?? "",
+  runCompletionSideEffect(logger, "run activity logging", () => {
+    db.core.activity.addActivity({
+      companyId: run.companyId,
+      actor: run.agentId,
+      action: `run.${event.status}`,
+      entityType: "run",
+      entityId: run.id,
+      detail: event.summary ?? event.errorMessage ?? "",
+    });
   });
 
   return { run, task, runOutcome };
@@ -85,11 +103,13 @@ export function finalizeRun(
 
 export function releaseCompletedRunWorkspaceLock(
   rfCtx: RunFinishedContext | null,
-  deps: Pick<HandlerDeps, "db">,
+  deps: Pick<HandlerDeps, "db" | "logger">,
 ): void {
   const workspaceId = rfCtx?.run.workspaceId;
   if (!workspaceId) return;
-  deps.db.core.workspaces.releaseWorkspaceLock(workspaceId, rfCtx.run.id);
+  runCompletionSideEffect(deps.logger, "workspace lock release", () => {
+    deps.db.core.workspaces.releaseWorkspaceLock(workspaceId, rfCtx.run.id);
+  });
 }
 
 export function accumulateAndRotateSession(
@@ -120,22 +140,26 @@ export function accumulateAndRotateSession(
   const session = db.core.tasks.getSessionById(agentRecord.sessionId);
   if (!session) return;
 
-  sessionService.accumulateTokenUsage(
-    session.id,
-    event.inputTokens ?? 0,
-    event.outputTokens ?? 0,
-    event.runId,
-  );
-  // Re-read after accumulation: evaluateRotation must see the counts
-  // that include this run, otherwise a run that just crossed the
-  // threshold waits a full additional cycle to rotate — the exact
-  // failure mode that let transcripts balloon past the context window.
-  const updatedSession = db.core.tasks.getSessionById(agentRecord.sessionId);
-  if (!updatedSession) return;
-  const rotationResult = sessionService.evaluateRotation(updatedSession);
-  if (rotationResult.shouldRotate) {
-    sessionService.rotateSession(updatedSession);
-    logger.info(`[session] Rotated session for agent ${run.agentId}: ${rotationResult.reason}`);
+  try {
+    sessionService.accumulateTokenUsage(
+      session.id,
+      event.inputTokens ?? 0,
+      event.outputTokens ?? 0,
+      event.runId,
+    );
+    // Re-read after accumulation: evaluateRotation must see the counts
+    // that include this run, otherwise a run that just crossed the
+    // threshold waits a full additional cycle to rotate — the exact
+    // failure mode that let transcripts balloon past the context window.
+    const updatedSession = db.core.tasks.getSessionById(agentRecord.sessionId);
+    if (!updatedSession) return;
+    const rotationResult = sessionService.evaluateRotation(updatedSession);
+    if (rotationResult.shouldRotate) {
+      sessionService.rotateSession(updatedSession);
+      logger.info(`[session] Rotated session for agent ${run.agentId}: ${rotationResult.reason}`);
+    }
+  } catch (error) {
+    logger.error(`[session] accumulation/rotation failed for run ${run.id}: ${errorMessage(error)}`);
   }
 }
 
@@ -147,20 +171,26 @@ export function emitAndNotifyCompletion(
   const { db, emitEvent, notify, logger } = deps;
   const { run, task, runOutcome } = rfCtx;
 
-  emitEvent({ type: "run-updated", runId: run.id, action: "completed" });
-  emitEvent({
-    type: "run-status",
-    runId: run.id,
-    status: event.status,
-    message: event.summary ?? event.errorMessage ?? event.status,
+  runCompletionSideEffect(logger, "run-updated event emission", () => {
+    emitEvent({ type: "run-updated", runId: run.id, action: "completed" });
+  });
+  runCompletionSideEffect(logger, "run-status event emission", () => {
+    emitEvent({
+      type: "run-status",
+      runId: run.id,
+      status: event.status,
+      message: event.summary ?? event.errorMessage ?? event.status,
+    });
   });
   if ((event.status === "failed" || event.status === "timed_out" || event.status === "interrupted") && task) {
-    notify({
-      title: "Task Failed",
-      body: `${task.title} -- manual intervention needed`,
-      urgency: "informational",
-      navigation: { section: "tasks", entityId: task.id },
-      batchKey: "failed_runs",
+    runCompletionSideEffect(logger, "task failure notification", () => {
+      notify({
+        title: "Task Failed",
+        body: `${task.title} -- manual intervention needed`,
+        urgency: "informational",
+        navigation: { section: "tasks", entityId: task.id },
+        batchKey: "failed_runs",
+      });
     });
   }
 
@@ -175,22 +205,28 @@ export function emitAndNotifyCompletion(
   }
 
   if (updatedAgent && runOutcome.budgetHardStopped) {
-    db.core.activity.addActivity({
-      companyId: updatedAgent.companyId,
-      actor: "system",
-      action: "agent.auto_paused",
-      entityType: "agent",
-      entityId: updatedAgent.id,
-      detail: `Budget exhausted at ${updatedAgent.spentMonthlyUsd.toFixed(2)} / ${updatedAgent.budgetMonthlyUsd.toFixed(2)} USD.`,
+    runCompletionSideEffect(logger, "budget auto-pause activity logging", () => {
+      db.core.activity.addActivity({
+        companyId: updatedAgent.companyId,
+        actor: "system",
+        action: "agent.auto_paused",
+        entityType: "agent",
+        entityId: updatedAgent.id,
+        detail: `Budget exhausted at ${updatedAgent.spentMonthlyUsd.toFixed(2)} / ${updatedAgent.budgetMonthlyUsd.toFixed(2)} USD.`,
+      });
     });
-    notify({
-      title: "Agent Paused",
-      body: `${updatedAgent.name} paused -- budget limit reached`,
-      urgency: "informational",
-      navigation: { section: "agents", entityId: updatedAgent.id },
-      batchKey: "agent_paused",
+    runCompletionSideEffect(logger, "budget auto-pause notification", () => {
+      notify({
+        title: "Agent Paused",
+        body: `${updatedAgent.name} paused -- budget limit reached`,
+        urgency: "informational",
+        navigation: { section: "agents", entityId: updatedAgent.id },
+        batchKey: "agent_paused",
+      });
+    });
+    runCompletionSideEffect(logger, "agent-updated event emission", () => {
+      emitEvent({ type: "agent-updated", agentId: updatedAgent.id, action: "paused" });
     });
-    emitEvent({ type: "agent-updated", agentId: updatedAgent.id, action: "paused" });
   }
 }
 
@@ -203,58 +239,97 @@ export function runPostCompletionAutomation(
   const { db, logger, isQuitting, wakeAgentIfPossible, processRunCompletion, onRunCompleted, notify, budgetService } = deps;
   const { destroyed, MAX_RETRY_ATTEMPTS, RETRY_COOLDOWN_MS, pendingRetryTimers } = context;
   const { run, task } = rfCtx;
+  let housekeepingStatus = event.status;
+  let housekeepingSummary = event.summary ?? null;
+  let housekeepingErrorMessage = event.errorMessage ?? null;
 
   // Policy-based incident check after run completion. Always runs once the
   // run is finalized — cost is read from the cost_entries SUM inside
   // finishRun/checkAndCreateIncidents, not from the worker event.
   if (budgetService && event.status === "succeeded") {
-    budgetService.checkAndCreateIncidents(run.companyId, run.agentId, task?.projectId ?? null);
+    try {
+      budgetService.checkAndCreateIncidents(run.companyId, run.agentId, task?.projectId ?? null);
+    } catch (error) {
+      logger.error(`[worker] budget incident check failed for run ${run.id}: ${errorMessage(error)}`);
+    }
   }
 
   if ((event.status === "failed" || event.status === "timed_out") && !isQuitting() && !destroyed && run.taskId) {
-    handleFailureEscalation(
-      {
-        db,
-        wakeAgentIfPossible,
-        notify: (title, body) =>
-          notify({ title, body, urgency: "critical", navigation: { section: "tasks", entityId: run.taskId ?? "" } }),
-        logger,
-      },
-      { taskId: run.taskId, agentId: run.agentId, companyId: run.companyId },
-      task,
-      event.status,
-      MAX_RETRY_ATTEMPTS,
-      RETRY_COOLDOWN_MS,
-      (fn, delayMs) => {
-        const retryTimer = setTimeout(() => {
-          pendingRetryTimers.delete(retryTimer);
-          if (isQuitting() || destroyed) return;
-          fn();
-        }, delayMs);
-        pendingRetryTimers.add(retryTimer);
-      },
-    );
+    try {
+      handleFailureEscalation(
+        {
+          db,
+          wakeAgentIfPossible,
+          notify: (title, body) =>
+            notify({ title, body, urgency: "critical", navigation: { section: "tasks", entityId: run.taskId ?? "" } }),
+          logger,
+        },
+        { taskId: run.taskId, agentId: run.agentId, companyId: run.companyId },
+        task,
+        event.status,
+        MAX_RETRY_ATTEMPTS,
+        RETRY_COOLDOWN_MS,
+        (fn, delayMs) => {
+          const retryTimer = setTimeout(() => {
+            pendingRetryTimers.delete(retryTimer);
+            if (isQuitting() || destroyed) return;
+            fn();
+          }, delayMs);
+          pendingRetryTimers.add(retryTimer);
+        },
+      );
+    } catch (error) {
+      logger.error(`[worker] failure escalation failed for run ${run.id}: ${errorMessage(error)}`);
+    }
   }
 
   // EXEC-05: Promote deferred wakes after run completion
   let hadDeferredWakes = false;
   if (!isQuitting() && !destroyed) {
-    const promoted = db.automation.wakeup.promoteWakeupRequests(run.agentId, run.companyId);
-    const pendingWakeTrigger = db.automation.wakeup.getPreferredWakeTrigger(run.agentId, run.companyId);
-    if (promoted > 0) {
-      logger.info(`[worker] Promoted ${promoted} deferred wake(s) for agent ${run.agentId}`);
-    }
-    if (pendingWakeTrigger) {
-      hadDeferredWakes = true;
-      logger.info(
-        `[worker] Processing pending wake(s) for agent ${run.agentId} with priority trigger "${pendingWakeTrigger}"`,
-      );
-      wakeAgentIfPossible(run.agentId, run.companyId, pendingWakeTrigger);
+    try {
+      const promoted = db.automation.wakeup.promoteWakeupRequests(run.agentId, run.companyId);
+      const pendingWakeTrigger = db.automation.wakeup.getPreferredWakeTrigger(run.agentId, run.companyId);
+      if (promoted > 0) {
+        logger.info(`[worker] Promoted ${promoted} deferred wake(s) for agent ${run.agentId}`);
+      }
+      if (pendingWakeTrigger) {
+        hadDeferredWakes = true;
+        logger.info(
+          `[worker] Processing pending wake(s) for agent ${run.agentId} with priority trigger "${pendingWakeTrigger}"`,
+        );
+        wakeAgentIfPossible(run.agentId, run.companyId, pendingWakeTrigger);
+      }
+    } catch (error) {
+      logger.error(`[worker] deferred wake processing failed for run ${run.id}: ${errorMessage(error)}`);
     }
   }
 
   if (!isQuitting() && !destroyed) {
-    processRunCompletion(run, event as z.infer<typeof workerMessageSchema> & { type: "run-finished" });
+    try {
+      processRunCompletion(run, event as z.infer<typeof workerMessageSchema> & { type: "run-finished" });
+    } catch (error) {
+      const message = errorMessage(error);
+      logger.error(`[worker] processRunCompletion failed for run ${run.id}: ${message}`);
+      housekeepingStatus = "failed";
+      housekeepingSummary = null;
+      housekeepingErrorMessage = message;
+      try {
+        db.core.runs.markRunCompletionFailure(run.id, message);
+      } catch (markError) {
+        logger.error(`[worker] markRunCompletionFailure failed for run ${run.id}: ${errorMessage(markError)}`);
+      }
+      if (task?.status === "in_progress") {
+        try {
+          db.core.tasks.advanceTaskStatus(
+            task.id,
+            "blocked",
+            `Run completion automation failed: ${message}`,
+          );
+        } catch (statusError) {
+          logger.error(`[worker] failed to block task ${task.id} after completion automation failure: ${errorMessage(statusError)}`);
+        }
+      }
+    }
   }
 
   // Run housekeeping: thread events + knowledge candidates
@@ -265,9 +340,9 @@ export function runPostCompletionAutomation(
         run.taskId,
         run.agentId,
         run.companyId,
-        event.status,
-        event.summary ?? null,
-        event.errorMessage ?? null,
+        housekeepingStatus,
+        housekeepingSummary,
+        housekeepingErrorMessage,
       );
     } catch (err) {
       logger.error(`[worker] onRunCompleted housekeeping failed: ${err instanceof Error ? err.message : String(err)}`);
@@ -275,7 +350,7 @@ export function runPostCompletionAutomation(
   }
 
   // Reset retry count on successful completion
-  if (event.status === "succeeded" && run.taskId) {
+  if (housekeepingStatus === "succeeded" && run.taskId) {
     handleSuccessReset(db, run.taskId, logger);
   }
 
diff --git a/tests/unit/worker-completion-boundary.test.ts b/tests/unit/worker-completion-boundary.test.ts
index c68da7ee..d72cda6d 100644
--- a/tests/unit/worker-completion-boundary.test.ts
+++ b/tests/unit/worker-completion-boundary.test.ts
@@ -24,19 +24,45 @@ function runFinishedMessage(runId: string) {
   };
 }
 
-function createHandlerDeps(calls: string[]) {
-  const releaseWorkspaceLock = vi.fn(() => calls.push("releaseWorkspaceLock"));
+function createHandlerDeps(calls: string[], options: {
+  taskId?: string | null;
+  taskStatus?: string;
+  sessionAccumulateThrows?: boolean;
+  processRunCompletionThrows?: boolean;
+  activityThrows?: boolean;
+  emitEventThrows?: boolean;
+  wakeupThrows?: boolean;
+  releaseWorkspaceThrows?: boolean;
+  markRunCompletionFailureThrows?: boolean;
+} = {}) {
+  const releaseWorkspaceLock = vi.fn(() => {
+    calls.push("releaseWorkspaceLock");
+    if (options.releaseWorkspaceThrows) {
+      throw new Error("workspace release failed");
+    }
+  });
   const finishRun = vi.fn(() => {
     calls.push("finishRun");
     return { budgetHardStopped: false };
   });
   const rotateSession = vi.fn(() => calls.push("rotateSession"));
-  const processRunCompletion = vi.fn(() => calls.push("processRunCompletion"));
+  const processRunCompletion = vi.fn(() => {
+    calls.push("processRunCompletion");
+    if (options.processRunCompletionThrows) {
+      throw new Error("processRunCompletion failed");
+    }
+  });
   const releaseRunResources = vi.fn((): RunResourceReleaseResult => {
     calls.push("releaseRunResources");
     return { ok: true as const };
   });
-  const markRunCompletionFailure = vi.fn(() => calls.push("markRunCompletionFailure"));
+  const markRunCompletionFailure = vi.fn(() => {
+    calls.push("markRunCompletionFailure");
+    if (options.markRunCompletionFailureThrows) {
+      throw new Error("mark completion failed");
+    }
+  });
+  const advanceTaskStatus = vi.fn(() => calls.push("advanceTaskStatus"));
 
   const db = {
     core: {
@@ -45,14 +71,21 @@ function createHandlerDeps(calls: string[]) {
           id: RUN_ID,
           companyId: "company-1",
           agentId: "agent-1",
-          taskId: null,
+          taskId: options.taskId ?? null,
           workspaceId: "workspace-1",
         })),
         finishRun,
         markRunCompletionFailure,
       },
       workspaces: { releaseWorkspaceLock },
-      activity: { addActivity: vi.fn(() => calls.push("addActivity")) },
+      activity: {
+        addActivity: vi.fn(() => {
+          calls.push("addActivity");
+          if (options.activityThrows) {
+            throw new Error("activity write failed");
+          }
+        }),
+      },
       entity: {
         getAgent: vi.fn(() => ({
           id: "agent-1",
@@ -60,11 +93,19 @@ function createHandlerDeps(calls: string[]) {
           reportsTo: "manager-1",
           sessionId: "session-1",
         })),
+        getTask: vi.fn(() => ({
+          id: options.taskId ?? "task-1",
+          companyId: "company-1",
+          agentId: "agent-1",
+          title: "Completion task",
+          status: options.taskStatus ?? "in_progress",
+        })),
         countActiveGoalsForCompany: vi.fn(() => 0),
       },
       tasks: {
         getSessionById: vi.fn(() => ({ id: "session-1" })),
         listAgentTasks: vi.fn(() => []),
+        advanceTaskStatus,
       },
       agents: {
         getDirectReports: vi.fn(() => []),
@@ -76,14 +117,24 @@ function createHandlerDeps(calls: string[]) {
     },
     automation: {
       wakeup: {
-        promoteWakeupRequests: vi.fn(() => 0),
+        promoteWakeupRequests: vi.fn(() => {
+          if (options.wakeupThrows) {
+            throw new Error("wakeup promotion failed");
+          }
+          return 0;
+        }),
         getPreferredWakeTrigger: vi.fn(() => null),
       },
     },
   };
 
   const sessionService = {
-    accumulateTokenUsage: vi.fn(() => calls.push("accumulateTokenUsage")),
+    accumulateTokenUsage: vi.fn(() => {
+      calls.push("accumulateTokenUsage");
+      if (options.sessionAccumulateThrows) {
+        throw new Error("session accumulation failed");
+      }
+    }),
     evaluateRotation: vi.fn(() => ({ shouldRotate: true, reason: "unit-test" })),
     rotateSession,
   };
@@ -98,7 +149,12 @@ function createHandlerDeps(calls: string[]) {
         error: vi.fn(),
       },
       isQuitting: vi.fn(() => false),
-      emitEvent: vi.fn(() => calls.push("emitEvent")),
+      emitEvent: vi.fn(() => {
+        calls.push("emitEvent");
+        if (options.emitEventThrows) {
+          throw new Error("emit failed");
+        }
+      }),
       wakeAgentIfPossible: vi.fn(() => null),
       processRunCompletion,
       notify: vi.fn(),
@@ -111,6 +167,7 @@ function createHandlerDeps(calls: string[]) {
     processRunCompletion,
     releaseRunResources,
     markRunCompletionFailure,
+    advanceTaskStatus,
   };
 }
 
@@ -227,6 +284,265 @@ describe("worker completion boundary", () => {
     expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
   });
 
+  it("continues completion when artifact failure marking throws", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      processRunCompletion,
+      releaseRunResources,
+      markRunCompletionFailure,
+    } = createHandlerDeps(calls, { markRunCompletionFailureThrows: true });
+    releaseRunResources.mockImplementationOnce(() => {
+      calls.push("releaseRunResources");
+      return { ok: false as const, errorMessage: "completion_reconcile failed" };
+    });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(markRunCompletionFailure).toHaveBeenCalledWith(RUN_ID, "completion_reconcile failed");
+    expect(processRunCompletion).toHaveBeenCalledWith(
+      expect.objectContaining({ id: RUN_ID }),
+      expect.objectContaining({
+        status: "failed",
+        errorMessage: "completion_reconcile failed",
+        usageStatus: "error_stop",
+      }),
+    );
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
+  it("continues completion automation when session accumulation fails", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      processRunCompletion,
+    } = createHandlerDeps(calls, { sessionAccumulateThrows: true });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(processRunCompletion).toHaveBeenCalled();
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
+  it("marks completion failed and blocks the task when completion automation throws", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      markRunCompletionFailure,
+      advanceTaskStatus,
+    } = createHandlerDeps(calls, {
+      taskId: "task-1",
+      taskStatus: "in_progress",
+      processRunCompletionThrows: true,
+    });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(markRunCompletionFailure).toHaveBeenCalledWith(RUN_ID, "processRunCompletion failed");
+    expect(advanceTaskStatus).toHaveBeenCalledWith(
+      "task-1",
+      "blocked",
+      expect.stringContaining("Run completion automation failed: processRunCompletion failed"),
+    );
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
+  it("releases workspace and acknowledges completion when activity logging fails", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      processRunCompletion,
+    } = createHandlerDeps(calls, { activityThrows: true });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(processRunCompletion).toHaveBeenCalled();
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
+  it("releases workspace and acknowledges completion when renderer event emission fails", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      processRunCompletion,
+    } = createHandlerDeps(calls, { emitEventThrows: true });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(processRunCompletion).toHaveBeenCalled();
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
+  it("releases workspace and acknowledges completion when deferred wake promotion fails", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      processRunCompletion,
+    } = createHandlerDeps(calls, { wakeupThrows: true });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(processRunCompletion).toHaveBeenCalled();
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
+  it("acknowledges completion when workspace release fails", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      processRunCompletion,
+    } = createHandlerDeps(calls, { releaseWorkspaceThrows: true });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(processRunCompletion).toHaveBeenCalled();
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
+  it("blocks the task and acknowledges completion when marking completion failure throws", async () => {
+    const calls: string[] = [];
+    const {
+      deps,
+      releaseWorkspaceLock,
+      markRunCompletionFailure,
+      advanceTaskStatus,
+    } = createHandlerDeps(calls, {
+      taskId: "task-1",
+      taskStatus: "in_progress",
+      processRunCompletionThrows: true,
+      markRunCompletionFailureThrows: true,
+    });
+    const worker = { postMessage: vi.fn(() => calls.push("completionAck")) };
+
+    await handleWorkerMessage(
+      runFinishedMessage(RUN_ID),
+      worker as never,
+      deps as never,
+      workerMessageSchema,
+      false,
+      2,
+      30_000,
+      new Map(),
+      3,
+      new Set(),
+      new Map(),
+    );
+
+    expect(markRunCompletionFailure).toHaveBeenCalledWith(RUN_ID, "processRunCompletion failed");
+    expect(advanceTaskStatus).toHaveBeenCalledWith(
+      "task-1",
+      "blocked",
+      expect.stringContaining("Run completion automation failed: processRunCompletion failed"),
+    );
+    expect(releaseWorkspaceLock).toHaveBeenCalledWith("workspace-1", RUN_ID);
+    expect(worker.postMessage).toHaveBeenCalledWith({ type: "run-completion-ack", runId: RUN_ID });
+  });
+
   it("keeps same-workspace runs queued until parent acknowledges completion", async () => {
     const parentPort = new EventEmitter() as EventEmitter & {
       postMessage: ReturnType<typeof vi.fn>;