diff --git a/apps/backend/internal/backendapp/main.go b/apps/backend/internal/backendapp/main.go
index c617682b2f..8180169953 100644
--- a/apps/backend/internal/backendapp/main.go
+++ b/apps/backend/internal/backendapp/main.go
@@ -1277,6 +1277,15 @@ func wireOfficeSvcsDependencies(
 	// relayed-comment activity rows get tagged with the originating
 	// run id (Tasks Touched on the run detail page).
 	services.OfficeSvcs.Channels.SetRunResolver(services.Office)
+	// Wire the office service as the dashboard's run resolver so the
+	// synchronous task_status_changed activity write (UpdateTaskStatus)
+	// tags its row with the originating run id, matching the async
+	// subscriber it replaced.
+	services.OfficeSvcs.Dashboard.SetRunResolver(services.Office)
+	// Wire the Office activity projection before task.state_changed events
+	// reach the WebSocket broadcaster, so workflow moves have durable timeline
+	// data when the frontend refetches the task detail.
+	services.Task.SetTaskStateActivityLogger(services.OfficeSvcs.Dashboard)
 	// Wire the office service as the retry canceller for task reassignment.
 	services.OfficeSvcs.Dashboard.SetRetryCanceller(services.Office)
 	// Wire the office service as the task canceller for status→cancelled hard-cancels.
diff --git a/apps/backend/internal/office/dashboard/completed_at_reopen_test.go b/apps/backend/internal/office/dashboard/completed_at_reopen_test.go
new file mode 100644
index 0000000000..0b97274be4
--- /dev/null
+++ b/apps/backend/internal/office/dashboard/completed_at_reopen_test.go
@@ -0,0 +1,73 @@
+package dashboard_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/jmoiron/sqlx"
+
+	"github.com/kandev/kandev/internal/office/dashboard"
+)
+
+// seedStatusChangeActivity inserts an office_activity_log row shaped like
+// the one DashboardService.UpdateTaskStatus's real event-subscriber
+// (handleTaskStatusChanged) would write in production. This test suite's
+// DashboardService is built without an event bus (see newTestDeps), so
+// calling UpdateTaskStatus directly here would not itself produce any
+// activity rows; seed them explicitly instead, matching the pattern used
+// by seedSummaryActivity in agent_summary_test.go.
+func seedStatusChangeActivity(t *testing.T, db *sqlx.DB, taskID, wsID, newStatus string, at time.Time) {
+	t.Helper()
+	_, err := db.Exec(`
+		INSERT INTO office_activity_log
+			(id, workspace_id, actor_type, actor_id, action,
+			 target_type, target_id, details, run_id, session_id, created_at)
+		VALUES (?, ?, 'system', 'office-scheduler', 'task_status_changed', 'task', ?, ?, '', '', ?)
+	`, "act-"+taskID+"-"+at.Format("20060102150405"), wsID, taskID,
+		fmt.Sprintf(`{"new_status":%q}`, newStatus), at.UTC().Format(time.RFC3339))
+	if err != nil {
+		t.Fatalf("seed status-change activity for %s: %v", taskID, err)
+	}
+}
+
+// TestGetTask_CompletedAtClearsWhenTaskReopened seeds a
+// todo -> in_progress -> done -> in_progress activity history (the shape
+// the office direct-update path writes) for a task currently in_progress,
+// and asserts the sidebar no longer reports a completedAt once the task
+// is reopened, even though it once completed. startedAt must survive the
+// reopen unaffected.
+func TestGetTask_CompletedAtClearsWhenTaskReopened(t *testing.T) {
+	deps := newTestDeps(t)
+	insertTestTask(t, deps.db, "reopen-task", "ws-reopen", "Reopen Task", "in_progress", 0)
+
+	base := time.Date(2026, 8, 1, 10, 0, 0, 0, time.UTC)
+	seedStatusChangeActivity(t, deps.db, "reopen-task", "ws-reopen", "in_progress", base)
+	seedStatusChangeActivity(t, deps.db, "reopen-task", "ws-reopen", "done", base.Add(time.Hour))
+	seedStatusChangeActivity(t, deps.db, "reopen-task", "ws-reopen", "in_progress", base.Add(2*time.Hour))
+
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/office/tasks/reopen-task", nil)
+	w := httptest.NewRecorder()
+	deps.router.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+
+	var resp dashboard.TaskResponse
+	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if resp.Task == nil {
+		t.Fatal("expected task in response")
+	}
+	if resp.Task.StartedAt == "" {
+		t.Error("expected startedAt to survive the reopen")
+	}
+	if resp.Task.CompletedAt != "" {
+		t.Errorf("expected completedAt cleared on a currently-open task, got %q", resp.Task.CompletedAt)
+	}
+}
diff --git a/apps/backend/internal/office/dashboard/dto.go b/apps/backend/internal/office/dashboard/dto.go
index 7c5d46b8ec..b6eb6e49f4 100644
--- a/apps/backend/internal/office/dashboard/dto.go
+++ b/apps/backend/internal/office/dashboard/dto.go
@@ -376,8 +376,16 @@ type TaskDTO struct {
 	Reviewers              []string       `json:"reviewers"`
 	Approvers              []string       `json:"approvers"`
 	Decisions              []*DecisionDTO `json:"decisions,omitempty"`
-	CreatedAt              string         `json:"createdAt"`
-	UpdatedAt              string         `json:"updatedAt"`
+	// StartedAt/CompletedAt are derived from the task's status-change
+	// activity log, not a persisted column (there is no started_at /
+	// completed_at on the tasks table). Only the detail handler
+	// (taskRowToDTO is called for both list and detail responses, but
+	// the derivation needs the timeline it doesn't have) sets these; see
+	// deriveTaskTimestamps in handler.go.
+	StartedAt   string `json:"startedAt,omitempty"`
+	CompletedAt string `json:"completedAt,omitempty"`
+	CreatedAt   string `json:"createdAt"`
+	UpdatedAt   string `json:"updatedAt"`
 	// IsSystem flags tasks that live in a kandev-managed system
 	// workflow (today: standing coordination; future: routine-fired).
 	// The Office Tasks UI hides these by default and surfaces a small
diff --git a/apps/backend/internal/office/dashboard/handler.go b/apps/backend/internal/office/dashboard/handler.go
index c3c4947d34..454a007ba4 100644
--- a/apps/backend/internal/office/dashboard/handler.go
+++ b/apps/backend/internal/office/dashboard/handler.go
@@ -462,6 +462,10 @@ func (h *Handler) getTask(c *gin.Context) {
 	h.attachDecisions(ctx, c, task.ID, dto)
 
 	statusChanges, _ := h.svc.ListStatusChanges(ctx, task.WorkspaceID, task.ID)
+	dto.StartedAt, dto.CompletedAt = deriveTaskTimestamps(statusChanges)
+	if !timelineStatusIsDone(dto.Status) {
+		dto.CompletedAt = ""
+	}
 	c.JSON(http.StatusOK, TaskResponse{Task: dto, Timeline: buildStatusTimeline(statusChanges)})
 }
 
@@ -496,19 +500,6 @@ func (h *Handler) attachDecisions(ctx context.Context, c *gin.Context, taskID st
 	}
 }
 
-func buildStatusTimeline(changes []TimelineEvent) []TimelineEventDTO {
-	timeline := make([]TimelineEventDTO, len(changes))
-	for i, ev := range changes {
-		timeline[i] = TimelineEventDTO{
-			Type: "status_change",
-			From: ev.From,
-			To:   ev.To,
-			At:   ev.At,
-		}
-	}
-	return timeline
-}
-
 func taskRowToDTO(r *sqlite.TaskRow, lbls []*sqlite.Label) *TaskDTO {
 	labels := make([]LabelDTO, len(lbls))
 	for i, l := range lbls {
diff --git a/apps/backend/internal/office/dashboard/service.go b/apps/backend/internal/office/dashboard/service.go
index d126e18c42..39a8d655ac 100644
--- a/apps/backend/internal/office/dashboard/service.go
+++ b/apps/backend/internal/office/dashboard/service.go
@@ -14,6 +14,7 @@ import (
 	"github.com/kandev/kandev/internal/office/shared"
 	taskmodels "github.com/kandev/kandev/internal/task/models"
 	workflowmodels "github.com/kandev/kandev/internal/workflow/models"
+	v1 "github.com/kandev/kandev/pkg/api/v1"
 
 	"go.uber.org/zap"
 )
@@ -144,6 +145,14 @@ type RetryCanceller interface {
 	CancelPendingRetriesForTask(ctx context.Context, taskID string) error
 }
 
+// RunResolver resolves the originating office run id for a task, used
+// to attribute the task_status_changed activity row back to the run
+// that produced the transition. Optional dependency — when nil, the
+// activity row is logged with an empty run_id. Mirrors channels.RunResolver.
+type RunResolver interface {
+	ResolveRunForTask(ctx context.Context, taskID string) string
+}
+
 // TaskCanceller hard-cancels a task's active execution. Used by the
 // reactivity pipeline when a task is moved to "cancelled" status.
 type TaskCanceller interface {
@@ -351,6 +360,7 @@ type DashboardService struct {
 	decisions        DecisionStore                   // workflow-domain decisions store (ADR 0005 Wave E); nil disables decision endpoints
 	routingProvider  RoutingProvider                 // optional; nil disables /routing endpoints (503)
 	attemptLister    RouteAttemptLister              // optional; nil disables attempt embedding on run-detail responses
+	runResolver      RunResolver                     // optional; nil means status-change activity rows have no run_id
 }
 
 // SetRoutingProvider wires the provider-routing seam used by the
@@ -451,6 +461,43 @@ func (s *DashboardService) SetRetryCanceller(c RetryCanceller) {
 	s.retryCanceller = c
 }
 
+// SetRunResolver wires the seam used to attribute status-change activity
+// rows back to the office run that produced them. Optional; when unset,
+// rows are logged with an empty run_id.
+func (s *DashboardService) SetRunResolver(r RunResolver) {
+	s.runResolver = r
+}
+
+// LogTaskStateChange records a task state transition for Office tasks before
+// the task service publishes its state-change notification. This keeps the
+// activity-backed timeline durable before clients refetch the task detail.
+// Non-Office tasks use the shared task service and are ignored here.
+func (s *DashboardService) LogTaskStateChange(
+	ctx context.Context, task *taskmodels.Task, oldState v1.TaskState,
+) {
+	if task == nil || oldState == task.State || s.activity == nil {
+		return
+	}
+	fields, err := s.repo.GetTaskExecutionFields(ctx, task.ID)
+	if err != nil || fields == nil || !fields.IsFromOffice {
+		return
+	}
+	wsID := fields.WorkspaceID
+	if wsID == "" {
+		wsID = task.WorkspaceID
+	}
+	runID := ""
+	if s.runResolver != nil {
+		runID = s.runResolver.ResolveRunForTask(ctx, task.ID)
+	}
+	details, _ := json.Marshal(map[string]string{
+		"new_status": string(task.State),
+		"old_status": string(oldState),
+	})
+	s.activity.LogActivityWithRun(ctx, wsID, "system", "orchestrator",
+		"task_status_changed", "task", task.ID, string(details), runID, "")
+}
+
 // SetTaskCanceller sets the canceller used to hard-cancel sessions when
 // a task is moved to "cancelled".
 func (s *DashboardService) SetTaskCanceller(c TaskCanceller) {
diff --git a/apps/backend/internal/office/dashboard/service_tasks.go b/apps/backend/internal/office/dashboard/service_tasks.go
index 87bcf1a285..c3ceb70b11 100644
--- a/apps/backend/internal/office/dashboard/service_tasks.go
+++ b/apps/backend/internal/office/dashboard/service_tasks.go
@@ -476,6 +476,7 @@ func (s *DashboardService) UpdateTaskStatus(ctx context.Context, req TaskStatusU
 	}
 
 	commentID := s.maybeCreateStatusComment(ctx, req)
+	s.logTaskStatusChangeActivity(ctx, req)
 	s.publishTaskStatusChanged(ctx, req)
 	s.runReactivityForStatus(ctx, req, commentID, preStatus)
 	s.maybeSupersedeOnRework(ctx, req.TaskID, preStatus, dbState)
@@ -497,6 +498,38 @@ func (s *DashboardService) UpdateTaskStatusAsAgent(
 	})
 }
 
+// logTaskStatusChangeActivity records the task_status_changed activity row
+// synchronously, in-process, before the OfficeTaskStatusChanged event is
+// published. This used to be an async event-bus subscriber
+// (office/service.Service.handleTaskStatusChanged); under a NATS-backed
+// bus, that subscriber and the WS broadcast subscriber that triggers the
+// frontend's task-detail refetch raced independently, so a browser GET
+// could land before the activity row existed and see stale Started/
+// Completed sidebar values with nothing left to trigger a corrective
+// refetch. Writing the row here, ahead of publishTaskStatusChanged,
+// makes the row durable before the event (and therefore the broadcast)
+// can ever fire, regardless of bus implementation. Best-effort: mirrors
+// logBlockerActivity's activity==nil guard.
+func (s *DashboardService) logTaskStatusChangeActivity(ctx context.Context, req TaskStatusUpdateRequest) {
+	if s.activity == nil {
+		return
+	}
+	wsID, _ := s.repo.GetTaskWorkspaceID(ctx, req.TaskID)
+	actorType := "system"
+	actorID := "office-scheduler"
+	if req.ActorAgentID != "" {
+		actorType = activityActorTypeAgent
+		actorID = req.ActorAgentID
+	}
+	runID := ""
+	if s.runResolver != nil {
+		runID = s.runResolver.ResolveRunForTask(ctx, req.TaskID)
+	}
+	s.activity.LogActivityWithRun(ctx, wsID, actorType, actorID,
+		"task_status_changed", "task", req.TaskID,
+		fmt.Sprintf(`{"new_status":%q}`, req.NewStatus), runID, "")
+}
+
 // applyApprovalGate redirects a "done" transition to in_review when
 // approvals are pending. Mutates dbState and apiStatus in place so the
 // rest of UpdateTaskStatus persists and emits the redirected status.
diff --git a/apps/backend/internal/office/dashboard/status_change_activity_test.go b/apps/backend/internal/office/dashboard/status_change_activity_test.go
new file mode 100644
index 0000000000..a033d5e57e
--- /dev/null
+++ b/apps/backend/internal/office/dashboard/status_change_activity_test.go
@@ -0,0 +1,147 @@
+package dashboard_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/kandev/kandev/internal/events"
+	"github.com/kandev/kandev/internal/events/bus"
+	"github.com/kandev/kandev/internal/office/dashboard"
+	taskmodels "github.com/kandev/kandev/internal/task/models"
+	v1 "github.com/kandev/kandev/pkg/api/v1"
+)
+
+// hasStatusChangeActivity reports whether the office_activity_log already
+// contains a task_status_changed row for taskID.
+func hasStatusChangeActivity(t *testing.T, deps *testDeps, taskID, wsID string) bool {
+	t.Helper()
+	entries, err := deps.repo.ListActivityEntriesByTarget(context.Background(), wsID, taskID, 50)
+	if err != nil {
+		t.Fatalf("list activity: %v", err)
+	}
+	for _, e := range entries {
+		if e.Action == "task_status_changed" {
+			return true
+		}
+	}
+	return false
+}
+
+// TestUpdateTaskStatus_LogsActivitySynchronously pins that UpdateTaskStatus
+// writes the task_status_changed activity row itself, in-process, rather
+// than depending on an event-bus subscriber to do it. This DashboardService
+// (built by newTestDeps) has no event bus wired at all, so before the fix
+// (the write lived solely in office/service.Service.handleTaskStatusChanged,
+// an OfficeTaskStatusChanged subscriber) this would never produce a row: the
+// event is never published without a bus, and nothing bridges to the
+// subscriber outside DashboardService anyway. If this activity write ever
+// moves back behind an event-bus round-trip, this test catches it.
+func TestUpdateTaskStatus_LogsActivitySynchronously(t *testing.T) {
+	deps := newTestDeps(t)
+	insertTestTask(t, deps.db, "sync-task", "ws-sync", "Sync Task", "todo", 0)
+
+	if err := deps.svc.UpdateTaskStatus(context.Background(), dashboard.TaskStatusUpdateRequest{
+		TaskID:    "sync-task",
+		NewStatus: "in_progress",
+	}); err != nil {
+		t.Fatalf("update task status: %v", err)
+	}
+
+	if !hasStatusChangeActivity(t, deps, "sync-task", "ws-sync") {
+		t.Fatal("expected task_status_changed activity row immediately after UpdateTaskStatus returns")
+	}
+}
+
+// LogTaskStateChange is the task-service seam used by workflow moves. It must
+// write the same durable projection as the Office status endpoint.
+func TestLogTaskStateChange_LogsOfficeTask(t *testing.T) {
+	deps := newTestDeps(t)
+	insertTestTask(t, deps.db, "workflow-task", "ws-workflow", "Workflow Task", "in_progress", 0)
+	if _, err := deps.db.Exec(`INSERT INTO workspaces (id, office_workflow_id) VALUES ('ws-workflow', 'wf-office')`); err != nil {
+		t.Fatalf("create Office workspace: %v", err)
+	}
+	if _, err := deps.db.Exec(`UPDATE tasks SET workflow_id = 'wf-office' WHERE id = 'workflow-task'`); err != nil {
+		t.Fatalf("attach task to Office workflow: %v", err)
+	}
+
+	deps.svc.LogTaskStateChange(context.Background(), &taskmodels.Task{
+		ID: "workflow-task", WorkspaceID: "ws-workflow", State: v1.TaskStateCompleted,
+	}, v1.TaskStateInProgress)
+
+	if !hasStatusChangeActivity(t, deps, "workflow-task", "ws-workflow") {
+		t.Fatal("expected task_status_changed activity row for a workflow state transition")
+	}
+}
+
+// orderingEventBus is a minimal bus.EventBus fake that, on Publish of
+// OfficeTaskStatusChanged, snapshots whether the activity row is already
+// persisted. Every other EventBus method is a harmless no-op; this fix
+// only touches the Publish ordering relative to the activity write.
+type orderingEventBus struct {
+	checkRow                 func() bool
+	activityPresentAtPublish bool
+	published                bool
+}
+
+func (b *orderingEventBus) Publish(_ context.Context, subject string, _ *bus.Event) error {
+	if subject == events.OfficeTaskStatusChanged {
+		b.published = true
+		b.activityPresentAtPublish = b.checkRow()
+	}
+	return nil
+}
+
+func (b *orderingEventBus) Subscribe(string, bus.EventHandler) (bus.Subscription, error) {
+	return nil, nil
+}
+
+func (b *orderingEventBus) QueueSubscribe(string, string, bus.EventHandler) (bus.Subscription, error) {
+	return nil, nil
+}
+
+func (b *orderingEventBus) Request(context.Context, string, *bus.Event, time.Duration) (*bus.Event, error) {
+	return nil, nil
+}
+
+func (b *orderingEventBus) Close()            {}
+func (b *orderingEventBus) IsConnected() bool { return true }
+
+// TestUpdateTaskStatus_LogsActivityBeforePublishingEvent reproduces the P1
+// race from PR fixup round 1: under a NATS-backed bus, the activity-log
+// write and the WS broadcast that triggers the frontend's task-detail
+// refetch were two independent async subscribers to the same
+// OfficeTaskStatusChanged event, with no ordering guarantee between them —
+// a browser GET could land before the activity row existed and see stale
+// Started/Completed values with nothing left to trigger a corrective
+// refetch. The fix sequences the activity write before the publish call
+// inside UpdateTaskStatus itself, so the row is guaranteed durable before
+// the event (and therefore any broadcast subscriber) can ever fire,
+// independent of the bus implementation. This test proves that ordering
+// directly: by the time Publish(OfficeTaskStatusChanged) is observed, the
+// activity row must already be queryable.
+func TestUpdateTaskStatus_LogsActivityBeforePublishingEvent(t *testing.T) {
+	deps := newTestDeps(t)
+	insertTestTask(t, deps.db, "race-task", "ws-race", "Race Task", "todo", 0)
+
+	fake := &orderingEventBus{}
+	fake.checkRow = func() bool {
+		return hasStatusChangeActivity(t, deps, "race-task", "ws-race")
+	}
+	deps.svc.SetEventBus(fake)
+
+	if err := deps.svc.UpdateTaskStatus(context.Background(), dashboard.TaskStatusUpdateRequest{
+		TaskID:    "race-task",
+		NewStatus: "in_progress",
+	}); err != nil {
+		t.Fatalf("update task status: %v", err)
+	}
+
+	if !fake.published {
+		t.Fatal("expected OfficeTaskStatusChanged to be published")
+	}
+	if !fake.activityPresentAtPublish {
+		t.Fatal("activity row was not yet persisted when the status-changed event was published: " +
+			"the WS broadcast (and any refetch it triggers) could race ahead of the activity write")
+	}
+}
diff --git a/apps/backend/internal/office/dashboard/timeline.go b/apps/backend/internal/office/dashboard/timeline.go
new file mode 100644
index 0000000000..d6883898b9
--- /dev/null
+++ b/apps/backend/internal/office/dashboard/timeline.go
@@ -0,0 +1,55 @@
+package dashboard
+
+import "strings"
+
+func buildStatusTimeline(changes []TimelineEvent) []TimelineEventDTO {
+	timeline := make([]TimelineEventDTO, len(changes))
+	for i, ev := range changes {
+		timeline[i] = TimelineEventDTO{
+			Type: "status_change",
+			From: ev.From,
+			To:   ev.To,
+			At:   ev.At,
+		}
+	}
+	return timeline
+}
+
+// timelineStatusIsInProgress and timelineStatusIsDone classify a timeline
+// event's "to" value into the office in_progress/done status buckets. The
+// activity log can contain API statuses, persisted states, or raw step names.
+func timelineStatusIsInProgress(raw string) bool {
+	switch strings.ToLower(strings.TrimSpace(raw)) {
+	case statusInProgressLowercase, "in progress":
+		return true
+	default:
+		return false
+	}
+}
+
+func timelineStatusIsDone(raw string) bool {
+	switch strings.ToLower(strings.TrimSpace(raw)) {
+	case statusDoneLowercase, "completed":
+		return true
+	default:
+		return false
+	}
+}
+
+// deriveTaskTimestamps derives Started and Completed timestamps from the
+// status-change timeline. Callers clear Completed when the task is reopened.
+func deriveTaskTimestamps(changes []TimelineEvent) (startedAt, completedAt string) {
+	for _, ev := range changes {
+		switch {
+		case timelineStatusIsInProgress(ev.To):
+			if startedAt == "" || ev.At < startedAt {
+				startedAt = ev.At
+			}
+		case timelineStatusIsDone(ev.To):
+			if ev.At > completedAt {
+				completedAt = ev.At
+			}
+		}
+	}
+	return startedAt, completedAt
+}
diff --git a/apps/backend/internal/office/dashboard/timeline_derivation_test.go b/apps/backend/internal/office/dashboard/timeline_derivation_test.go
new file mode 100644
index 0000000000..81da87107c
--- /dev/null
+++ b/apps/backend/internal/office/dashboard/timeline_derivation_test.go
@@ -0,0 +1,93 @@
+package dashboard
+
+import "testing"
+
+// TestDeriveTaskTimestamps locks down the Started/Completed sidebar
+// derivation described in docs/specs/office/tasks.md: startedAt is the
+// earliest transition into in_progress, completedAt is the latest
+// transition into done. A regression here silently reverts the Office
+// task detail sidebar to permanently blank Started/Completed rows.
+func TestDeriveTaskTimestamps(t *testing.T) {
+	cases := []struct {
+		name          string
+		changes       []TimelineEvent
+		wantStarted   string
+		wantCompleted string
+	}{
+		{
+			name:          "no status changes",
+			changes:       nil,
+			wantStarted:   "",
+			wantCompleted: "",
+		},
+		{
+			name: "todo to in_progress only",
+			changes: []TimelineEvent{
+				{From: "todo", To: "in_progress", At: "2026-08-01T10:00:00Z"},
+			},
+			wantStarted:   "2026-08-01T10:00:00Z",
+			wantCompleted: "",
+		},
+		{
+			name: "full todo -> in_progress -> done",
+			changes: []TimelineEvent{
+				// ListActivityEntriesByTarget returns rows DESC by created_at.
+				{From: "in_progress", To: "done", At: "2026-08-01T12:00:00Z"},
+				{From: "todo", To: "in_progress", At: "2026-08-01T10:00:00Z"},
+			},
+			wantStarted:   "2026-08-01T10:00:00Z",
+			wantCompleted: "2026-08-01T12:00:00Z",
+		},
+		{
+			name: "reopened: done -> in_progress -> done, expect latest done",
+			changes: []TimelineEvent{
+				{From: "in_progress", To: "done", At: "2026-08-03T09:00:00Z"},
+				{From: "done", To: "in_progress", At: "2026-08-02T08:00:00Z"},
+				{From: "in_progress", To: "done", At: "2026-08-01T12:00:00Z"},
+				{From: "todo", To: "in_progress", At: "2026-08-01T10:00:00Z"},
+			},
+			wantStarted:   "2026-08-01T10:00:00Z",
+			wantCompleted: "2026-08-03T09:00:00Z",
+		},
+		{
+			name: "out-of-order input still resolves min/max",
+			changes: []TimelineEvent{
+				{From: "todo", To: "in_progress", At: "2026-08-05T10:00:00Z"},
+				{From: "in_progress", To: "done", At: "2026-08-01T12:00:00Z"},
+				{From: "todo", To: "in_progress", At: "2026-08-01T09:00:00Z"},
+			},
+			wantStarted:   "2026-08-01T09:00:00Z",
+			wantCompleted: "2026-08-01T12:00:00Z",
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			gotStarted, gotCompleted := deriveTaskTimestamps(c.changes)
+			if gotStarted != c.wantStarted {
+				t.Errorf("startedAt = %q, want %q", gotStarted, c.wantStarted)
+			}
+			if gotCompleted != c.wantCompleted {
+				t.Errorf("completedAt = %q, want %q", gotCompleted, c.wantCompleted)
+			}
+		})
+	}
+}
+
+// TestDeriveTaskTimestampsStepNameVariants covers the workflow-engine
+// TaskMoved producer, whose activity entries carry raw step names ("In
+// Progress", "Done") rather than the already-normalized lowercase status
+// strings the direct Office status-update path writes. Both producers
+// write the same "task_status_changed" activity action.
+func TestDeriveTaskTimestampsStepNameVariants(t *testing.T) {
+	changes := []TimelineEvent{
+		{From: "In Progress", To: "Done", At: "2026-08-01T12:00:00Z"},
+		{From: "Todo", To: "In Progress", At: "2026-08-01T10:00:00Z"},
+	}
+	gotStarted, gotCompleted := deriveTaskTimestamps(changes)
+	if gotStarted != "2026-08-01T10:00:00Z" {
+		t.Errorf("startedAt = %q, want 2026-08-01T10:00:00Z", gotStarted)
+	}
+	if gotCompleted != "2026-08-01T12:00:00Z" {
+		t.Errorf("completedAt = %q, want 2026-08-01T12:00:00Z", gotCompleted)
+	}
+}
diff --git a/apps/backend/internal/office/service/event_subscribers.go b/apps/backend/internal/office/service/event_subscribers.go
index 2ec479d4c1..1765a35afa 100644
--- a/apps/backend/internal/office/service/event_subscribers.go
+++ b/apps/backend/internal/office/service/event_subscribers.go
@@ -90,15 +90,6 @@ type ApprovalResolvedData struct {
 	Type                      string `json:"type"`
 }
 
-// TaskStatusChangedData represents the payload of an office.task.status_changed event.
-type TaskStatusChangedData struct {
-	TaskID       string `json:"task_id"`
-	WorkspaceID  string `json:"workspace_id"`
-	NewStatus    string `json:"new_status"`
-	Comment      string `json:"comment"`
-	ActorAgentID string `json:"actor_agent_id"`
-}
-
 // AgentLifecycleData is the subset of agent lifecycle event data needed by office.
 //
 // AgentID is populated by the lifecycle manager for taskless runs
@@ -219,7 +210,6 @@ func (s *Service) RegisterEventSubscribers(eb bus.EventBus) error {
 		{events.TaskMoved, s.handleTaskMoved},
 		{events.OfficeApprovalResolved, s.handleApprovalResolved},
 		{events.OfficeCommentCreated, s.handleCommentCreated},
-		{events.OfficeTaskStatusChanged, s.handleTaskStatusChanged},
 		{events.AgentCompleted, maybeAsync(s.handleAgentCompleted)},
 		// AgentStopped fires when StopAgent is called (e.g. office
 		// fire-and-forget turn-complete teardown). Same handler — both
@@ -844,12 +834,13 @@ func (s *Service) queueTaskAssignedRun(
 	return s.QueueRun(ctx, agentProfileID, RunReasonTaskAssigned, payload, key)
 }
 
-// handleTaskMoved logs the step change to the activity log and queues
+// handleTaskMoved keeps the legacy named-step activity fallback and queues
 // downstream blocker / children-completed runs when a task lands in a
-// terminal step. Stage progression itself is owned by the workflow
-// engine (the orchestrator subscribes to TaskMoved and fires
-// on_exit / on_enter); this handler covers the side-effects the engine
-// path doesn't yet emit.
+// terminal step. Canonical task-state activity is written by the task service
+// before task.state_changed is published, so the workflow move path is durable
+// before any WebSocket refetch can run. Stage progression itself is owned by
+// the workflow engine (the orchestrator subscribes to TaskMoved and fires
+// on_exit / on_enter).
 func (s *Service) handleTaskMoved(ctx context.Context, event *bus.Event) error {
 	data, err := decodeEventData[TaskMovedData](event)
 	if err != nil || data.AssigneeAgentProfileID == "" {
@@ -996,33 +987,6 @@ func (s *Service) queueChildrenCompletedRun(ctx context.Context, parentID string
 		engine.OnChildrenCompletedPayload{ChildSummaries: summaries}, key)
 }
 
-// handleTaskStatusChanged logs status-change activity. Stage progression
-// (Work → Review → Approval → Done) is owned by the workflow engine via
-// the on_exit / on_enter triggers fired by the orchestrator on
-// TaskMoved; the legacy ExecutionPolicy transition path was removed in
-// Phase 4 of task-model-unification.
-func (s *Service) handleTaskStatusChanged(ctx context.Context, event *bus.Event) error {
-	data, err := decodeEventData[TaskStatusChangedData](event)
-	if err != nil || data.TaskID == "" || data.NewStatus == "" {
-		return nil
-	}
-
-	fields, _ := s.repo.GetTaskExecutionFields(ctx, data.TaskID)
-	if fields != nil && fields.WorkspaceID != "" {
-		actorType := "system"
-		actorID := "office-scheduler"
-		if data.ActorAgentID != "" {
-			actorType = participantTypeAgent
-			actorID = data.ActorAgentID
-		}
-		runID := s.ResolveRunForTask(ctx, data.TaskID)
-		s.LogActivityWithRun(ctx, fields.WorkspaceID, actorType, actorID,
-			"task_status_changed", "task", data.TaskID,
-			fmt.Sprintf(`{"new_status":%q}`, data.NewStatus), runID, "")
-	}
-	return nil
-}
-
 // handleCommentCreated loads the comment and relays it to external channels.
 func (s *Service) handleCommentCreated(ctx context.Context, event *bus.Event) error {
 	data, err := decodeEventData[CommentPostedData](event)
diff --git a/apps/backend/internal/office/service/event_subscribers_test.go b/apps/backend/internal/office/service/event_subscribers_test.go
index 6be6651d3e..5c9d1fb06b 100644
--- a/apps/backend/internal/office/service/event_subscribers_test.go
+++ b/apps/backend/internal/office/service/event_subscribers_test.go
@@ -783,38 +783,6 @@ func TestMovedToDone_WithoutExecutionPolicy_NormalCompletion(t *testing.T) {
 	}
 }
 
-func TestHandleTaskStatusChanged_LogsActivity(t *testing.T) {
-	svc, eb := newTestServiceWithBus(t)
-	ctx := context.Background()
-
-	createTestAgent(t, svc, "ws-1", "worker-status")
-	taskID := createOfficeTask(t, svc, "ws-1", "worker-status")
-
-	statusEvt := bus.NewEvent(events.OfficeTaskStatusChanged, "test", map[string]interface{}{
-		"task_id":      taskID,
-		"new_status":   "in_progress",
-		"workspace_id": "ws-1",
-	})
-	if err := eb.Publish(ctx, events.OfficeTaskStatusChanged, statusEvt); err != nil {
-		t.Fatalf("publish office.task.status_changed: %v", err)
-	}
-
-	activity, err := svc.ListActivity(ctx, "ws-1", 50)
-	if err != nil {
-		t.Fatalf("list activity: %v", err)
-	}
-	found := false
-	for _, a := range activity {
-		if a.Action == "task_status_changed" && a.TargetID == taskID {
-			found = true
-			break
-		}
-	}
-	if !found {
-		t.Errorf("expected activity entry with action 'task_status_changed' for task %s, got %+v", taskID, activity)
-	}
-}
-
 func TestAutoPostAgentComment_CreatesSessionComment(t *testing.T) {
 	svc, eb := newTestServiceWithBus(t)
 	ctx := context.Background()
diff --git a/apps/backend/internal/task/service/service.go b/apps/backend/internal/task/service/service.go
index a42de0b45e..6ae94fad9e 100644
--- a/apps/backend/internal/task/service/service.go
+++ b/apps/backend/internal/task/service/service.go
@@ -344,6 +344,7 @@ type Service struct {
 	// other's insert and commit a cycle between them.
 	dependencyEdgeMu       sync.Mutex
 	comments               CommentRepository
+	taskStateActivity      TaskStateActivityLogger
 	secretStore            secrets.SecretStore
 	workspaceSecretDeleter WorkspaceSecretDeleter
 	baseBranchPusher       AgentBaseBranchPusher
diff --git a/apps/backend/internal/task/service/service_events.go b/apps/backend/internal/task/service/service_events.go
index 4336fb942f..88ff15c454 100644
--- a/apps/backend/internal/task/service/service_events.go
+++ b/apps/backend/internal/task/service/service_events.go
@@ -440,6 +440,12 @@ func (s *Service) publishTaskEventNow(ctx context.Context, eventType string, tas
 	for k, v := range extra {
 		data[k] = v
 	}
+	if eventType == events.TaskStateChanged && oldState != nil && s.taskStateActivity != nil {
+		// Write the Office read-model row before publishing the event. The
+		// WebSocket broadcaster can then trigger a detail GET without racing
+		// the activity projection that supplies Started and Completed.
+		s.taskStateActivity.LogTaskStateChange(ctx, task, *oldState)
+	}
 
 	event := bus.NewEvent(eventType, "task-service", data)
 	err := s.eventBus.Publish(ctx, eventType, event)
diff --git a/apps/backend/internal/task/service/service_office.go b/apps/backend/internal/task/service/service_office.go
index e280074775..f58d8597de 100644
--- a/apps/backend/internal/task/service/service_office.go
+++ b/apps/backend/internal/task/service/service_office.go
@@ -8,6 +8,7 @@ import (
 
 	orchmodels "github.com/kandev/kandev/internal/office/models"
 	"github.com/kandev/kandev/internal/task/models"
+	v1 "github.com/kandev/kandev/pkg/api/v1"
 )
 
 // BlockerRepository provides access to task blocker persistence.
@@ -36,6 +37,13 @@ type CommentRepository interface {
 	ListTaskComments(ctx context.Context, taskID string) ([]*orchmodels.TaskComment, error)
 }
 
+// TaskStateActivityLogger records a durable status transition before the task
+// state event is published. Optional callers can use this seam to keep
+// read-model activity and WebSocket notifications ordered.
+type TaskStateActivityLogger interface {
+	LogTaskStateChange(ctx context.Context, task *models.Task, oldState v1.TaskState)
+}
+
 // SetBlockerRepository wires the blocker repository for office integration.
 func (s *Service) SetBlockerRepository(repo BlockerRepository) {
 	s.blockers = repo
@@ -46,6 +54,12 @@ func (s *Service) SetCommentRepository(repo CommentRepository) {
 	s.comments = repo
 }
 
+// SetTaskStateActivityLogger wires the optional durable activity writer used
+// before task.state_changed notifications are published.
+func (s *Service) SetTaskStateActivityLogger(logger TaskStateActivityLogger) {
+	s.taskStateActivity = logger
+}
+
 // GetLastAgentMessage returns the content of the most recent agent message
 // in a session. Used by the office comment bridge to auto-post agent responses.
 func (s *Service) GetLastAgentMessage(ctx context.Context, sessionID string) (string, error) {
diff --git a/apps/backend/internal/task/service/service_resources_workflows_test.go b/apps/backend/internal/task/service/service_resources_workflows_test.go
index 00d2474c33..c66e3c68d7 100644
--- a/apps/backend/internal/task/service/service_resources_workflows_test.go
+++ b/apps/backend/internal/task/service/service_resources_workflows_test.go
@@ -121,6 +121,47 @@ func TestStandaloneTaskEventPublishers(t *testing.T) {
 	}
 }
 
+type recordingTaskStateActivityLogger struct {
+	called          bool
+	taskID          string
+	old             v1.TaskState
+	new             v1.TaskState
+	publishedBefore int
+	eventBus        *MockEventBus
+}
+
+func (l *recordingTaskStateActivityLogger) LogTaskStateChange(
+	_ context.Context, task *models.Task, oldState v1.TaskState,
+) {
+	l.called = true
+	l.taskID = task.ID
+	l.old = oldState
+	l.new = task.State
+	if l.eventBus != nil {
+		l.publishedBefore = len(l.eventBus.GetPublishedEvents())
+	}
+}
+
+func TestTaskStateActivityIsLoggedBeforeStateEvent(t *testing.T) {
+	svc, eventBus, _ := createTestService(t)
+	activity := &recordingTaskStateActivityLogger{eventBus: eventBus}
+	svc.SetTaskStateActivityLogger(activity)
+
+	svc.PublishTaskStateChanged(context.Background(), &models.Task{
+		ID: "task-state-activity", WorkspaceID: "ws-1", State: v1.TaskStateCompleted,
+	}, v1.TaskStateInProgress)
+
+	if !activity.called || activity.taskID != "task-state-activity" {
+		t.Fatalf("activity logger call = %+v, want task-state-activity", activity)
+	}
+	if activity.old != v1.TaskStateInProgress || activity.new != v1.TaskStateCompleted {
+		t.Fatalf("activity transition = %q -> %q", activity.old, activity.new)
+	}
+	if activity.publishedBefore != 0 {
+		t.Fatalf("activity logger observed %d published events, want 0", activity.publishedBefore)
+	}
+}
+
 func TestPublishAfterTaskEventsRunsCallback(t *testing.T) {
 	svc, _, _ := createTestService(t)
 	ctx := context.Background()
diff --git a/apps/web/app/office/tasks/[id]/map-office-task.test.ts b/apps/web/app/office/tasks/[id]/map-office-task.test.ts
new file mode 100644
index 0000000000..39dd8d4393
--- /dev/null
+++ b/apps/web/app/office/tasks/[id]/map-office-task.test.ts
@@ -0,0 +1,61 @@
+import { describe, expect, it } from "vitest";
+import type { OfficeTask } from "@/lib/state/slices/office/types";
+import { mapOfficeTaskToTask } from "./map-office-task";
+
+function baseOfficeTask(overrides: Partial<OfficeTask> = {}): OfficeTask {
+  return {
+    id: "task-1",
+    workspaceId: "ws-1",
+    identifier: "OFF-1",
+    title: "Test task",
+    status: "in_progress",
+    priority: "medium",
+    createdAt: "2026-08-01T09:00:00Z",
+    updatedAt: "2026-08-01T09:00:00Z",
+    ...overrides,
+  };
+}
+
+describe("mapOfficeTaskToTask", () => {
+  it("maps startedAt and completedAt through when the backend sends them", () => {
+    const raw = baseOfficeTask({
+      startedAt: "2026-08-01T10:00:00Z",
+      completedAt: "2026-08-01T12:00:00Z",
+    });
+
+    const task = mapOfficeTaskToTask(raw);
+
+    expect(task.startedAt).toBe("2026-08-01T10:00:00Z");
+    expect(task.completedAt).toBe("2026-08-01T12:00:00Z");
+  });
+
+  it("leaves startedAt and completedAt undefined when the backend omits them", () => {
+    const raw = baseOfficeTask();
+
+    const task = mapOfficeTaskToTask(raw);
+
+    expect(task.startedAt).toBeUndefined();
+    expect(task.completedAt).toBeUndefined();
+  });
+
+  it("always maps createdBy to an empty string (no source of truth yet)", () => {
+    const task = mapOfficeTaskToTask(baseOfficeTask());
+
+    expect(task.createdBy).toBe("");
+  });
+
+  // The detail page seeds its Task from the store-held OfficeTask before the
+  // API GET resolves. Preserve rawStatus so execution indicators keep their
+  // live/ready distinction during that initial render.
+  it("carries rawStatus through when the store holds one", () => {
+    const mapped = mapOfficeTaskToTask(baseOfficeTask({ status: "todo", rawStatus: "SCHEDULING" }));
+
+    expect(mapped.rawStatus).toBe("SCHEDULING");
+  });
+
+  it("falls back to the canonical status when rawStatus is absent", () => {
+    const mapped = mapOfficeTaskToTask(baseOfficeTask({ status: "in_progress" }));
+
+    expect(mapped.rawStatus).toBe("in_progress");
+  });
+});
diff --git a/apps/web/app/office/tasks/[id]/map-office-task.ts b/apps/web/app/office/tasks/[id]/map-office-task.ts
new file mode 100644
index 0000000000..cadce4300b
--- /dev/null
+++ b/apps/web/app/office/tasks/[id]/map-office-task.ts
@@ -0,0 +1,65 @@
+import type { TaskDecisionDTO } from "@/lib/api/domains/office-api";
+import type { OfficeTask } from "@/lib/state/slices/office/types";
+import type { Task, TaskDecision } from "./types";
+
+export function mapDecisionDTO(d: TaskDecisionDTO): TaskDecision {
+  return {
+    id: d.id,
+    taskId: d.task_id,
+    deciderType: d.decider_type,
+    deciderId: d.decider_id,
+    deciderName: d.decider_name ?? "",
+    role: d.role,
+    decision: d.decision,
+    comment: d.comment ?? "",
+    createdAt: d.created_at,
+  };
+}
+
+export function mapOfficeTaskToTask(raw: OfficeTask): Task {
+  // The server DTO includes reviewers/approvers/decisions even though the
+  // strongly-typed OfficeTask only declares the cross-cutting fields. We
+  // read those extra props off the raw object.
+  const extra = raw as OfficeTask & {
+    reviewers?: string[];
+    approvers?: string[];
+    decisions?: TaskDecisionDTO[];
+    blockedBy?: string[];
+  };
+  return {
+    id: raw.id,
+    workspaceId: raw.workspaceId,
+    identifier: raw.identifier,
+    title: raw.title,
+    description: raw.description,
+    status: raw.status as Task["status"],
+    rawStatus: raw.rawStatus ?? raw.status,
+    priority: (raw.priority || "medium") as Task["priority"],
+    labels: (raw.labels ?? []).map((l) =>
+      typeof l === "string" ? { name: l, color: "#6b7280" } : l,
+    ),
+    assigneeAgentProfileId: raw.assigneeAgentProfileId,
+    parentId: raw.parentId,
+    projectId: raw.projectId,
+    blockedBy: extra.blockedBy ?? [],
+    blocking: [],
+    children: (raw.children ?? []).map((child) => ({
+      id: child.id,
+      identifier: child.identifier,
+      title: child.title,
+      status: child.status as Task["status"],
+      blockedBy: child.blockedBy ?? [],
+      createdAt: child.createdAt,
+    })),
+    reviewers: extra.reviewers ?? [],
+    approvers: extra.approvers ?? [],
+    decisions: (extra.decisions ?? []).map(mapDecisionDTO),
+    createdBy: "",
+    startedAt: raw.startedAt,
+    completedAt: raw.completedAt,
+    createdAt: raw.createdAt,
+    updatedAt: raw.updatedAt,
+    executionPolicy: raw.executionPolicy,
+    executionState: raw.executionState,
+  };
+}
diff --git a/apps/web/app/office/tasks/[id]/page.test.ts b/apps/web/app/office/tasks/[id]/page.test.ts
deleted file mode 100644
index dfbda38c7f..0000000000
--- a/apps/web/app/office/tasks/[id]/page.test.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-import { describe, expect, it } from "vitest";
-import { mapOfficeTaskToTask } from "./page";
-import type { OfficeTask } from "@/lib/state/slices/office/types";
-
-const baseRaw: OfficeTask = {
-  id: "task-1",
-  workspaceId: "workspace-1",
-  identifier: "E2E-1",
-  title: "Mapper regression task",
-  status: "todo",
-  priority: "medium",
-  createdAt: "2026-05-01T10:00:00Z",
-  updatedAt: "2026-05-01T10:00:00Z",
-};
-
-describe("mapOfficeTaskToTask", () => {
-  // Regression: the detail page seeds its Task from the store-held OfficeTask
-  // before the API GET resolves (page.tsx's useIssueData). Dropping rawStatus
-  // here silently breaks ExecutionIndicator's Live/Ready sub-state distinction
-  // for however long the seeded task is shown — see task-advanced-mode.test.tsx
-  // and OfficeSimplePane.test.tsx for the consumer-level regression.
-  it("carries rawStatus through when the store holds one", () => {
-    const mapped = mapOfficeTaskToTask({ ...baseRaw, status: "todo", rawStatus: "SCHEDULING" });
-
-    expect(mapped.rawStatus).toBe("SCHEDULING");
-  });
-
-  it("falls back to the canonical status when rawStatus is absent", () => {
-    const mapped = mapOfficeTaskToTask({ ...baseRaw, status: "in_progress" });
-
-    expect(mapped.rawStatus).toBe("in_progress");
-  });
-});
diff --git a/apps/web/app/office/tasks/[id]/page.tsx b/apps/web/app/office/tasks/[id]/page.tsx
index ad4e63010c..c76c3f579d 100644
--- a/apps/web/app/office/tasks/[id]/page.tsx
+++ b/apps/web/app/office/tasks/[id]/page.tsx
@@ -4,13 +4,13 @@ import { use, useState, useEffect, useRef, useCallback, useMemo, Suspense } from
 import { useRouter, useSearchParams } from "@/lib/routing/client-router";
 import { useAppStore } from "@/components/state-provider";
 import { useOfficeRefetch } from "@/hooks/use-office-refetch";
+import { useLatestOnly } from "@/hooks/use-latest-only";
 import { TaskOptimisticContextProvider } from "@/hooks/use-optimistic-task-mutation";
 import {
   getTask,
   listActivityForTarget,
   listComments,
   type TaskCommentResponse,
-  type TaskDecisionDTO,
 } from "@/lib/api/domains/office-api";
 import { listTaskSessions } from "@/lib/api/domains/session-api";
 import {
@@ -21,19 +21,13 @@ import { OfficeSimplePane } from "@/components/task/simple/OfficeSimplePane";
 import { TaskAdvancedMode } from "./task-advanced-mode";
 import { IssueDetailSkeleton } from "./task-detail-skeleton";
 import { TaskBody, resolveTaskBodyMode, type TaskBodyMode } from "@/components/task/TaskBody";
-import type {
-  Task,
-  TaskComment,
-  TaskActivityEntry,
-  TaskDecision,
-  TaskSession,
-  TimelineEvent,
-} from "./types";
-import type { ActivityEntry, OfficeTask } from "@/lib/state/slices/office/types";
+import type { Task, TaskComment, TaskActivityEntry, TaskSession, TimelineEvent } from "./types";
+import type { ActivityEntry } from "@/lib/state/slices/office/types";
 import type { TaskSession as ApiTaskSession } from "@/lib/types/http";
 import { useSessionLiveSyncSubscriptions } from "./use-session-live-sync";
 import { useTranslation } from "react-i18next";
 import { t } from "@/lib/i18n";
+import { mapOfficeTaskToTask } from "./map-office-task";
 
 type IssueDetailPageProps = {
   params: Promise<{ id: string }>;
@@ -44,66 +38,6 @@ type IssueDetailPageProps = {
 // cleared and must not be resurrected).
 const SESSION_METADATA_ABSENT = "\u0000absent\u0000";
 
-function mapDecisionDTO(d: TaskDecisionDTO): TaskDecision {
-  return {
-    id: d.id,
-    taskId: d.task_id,
-    deciderType: d.decider_type,
-    deciderId: d.decider_id,
-    deciderName: d.decider_name ?? "",
-    role: d.role,
-    decision: d.decision,
-    comment: d.comment ?? "",
-    createdAt: d.created_at,
-  };
-}
-
-export function mapOfficeTaskToTask(raw: OfficeTask): Task {
-  // The server DTO includes reviewers/approvers/decisions even though the
-  // strongly-typed OfficeTask only declares the cross-cutting fields. We
-  // read those extra props off the raw object.
-  const extra = raw as OfficeTask & {
-    reviewers?: string[];
-    approvers?: string[];
-    decisions?: TaskDecisionDTO[];
-    blockedBy?: string[];
-  };
-  return {
-    id: raw.id,
-    workspaceId: raw.workspaceId,
-    identifier: raw.identifier,
-    title: raw.title,
-    description: raw.description,
-    status: raw.status as Task["status"],
-    rawStatus: raw.rawStatus ?? raw.status,
-    priority: (raw.priority || "medium") as Task["priority"],
-    labels: (raw.labels ?? []).map((l) =>
-      typeof l === "string" ? { name: l, color: "#6b7280" } : l,
-    ),
-    assigneeAgentProfileId: raw.assigneeAgentProfileId,
-    parentId: raw.parentId,
-    projectId: raw.projectId,
-    blockedBy: extra.blockedBy ?? [],
-    blocking: [],
-    children: (raw.children ?? []).map((child) => ({
-      id: child.id,
-      identifier: child.identifier,
-      title: child.title,
-      status: child.status as Task["status"],
-      blockedBy: child.blockedBy ?? [],
-      createdAt: child.createdAt,
-    })),
-    reviewers: extra.reviewers ?? [],
-    approvers: extra.approvers ?? [],
-    decisions: (extra.decisions ?? []).map(mapDecisionDTO),
-    createdBy: "",
-    createdAt: raw.createdAt,
-    updatedAt: raw.updatedAt,
-    executionPolicy: raw.executionPolicy,
-    executionState: raw.executionState,
-  };
-}
-
 function mapCommentResponse(c: TaskCommentResponse): TaskComment {
   return {
     id: c.id,
@@ -316,9 +250,19 @@ function useTaskOptimisticHelpers(
   // (priority / project / parent / blockers / participants / assignee).
   // The optimistic patch we applied locally gets reconciled with server
   // state.
+  //
+  // A WS-driven trigger can fire again before a prior GET resolves (two
+  // status changes in quick succession, ordinary network jitter). Without
+  // a guard, a slower earlier response can land after a faster later one
+  // and overwrite fresher task state with stale data. useLatestOnly
+  // discards a response once a newer refetchTask call has started,
+  // regardless of arrival order.
+  const { begin, isCurrent } = useLatestOnly();
   const refetchTask = useCallback(async () => {
+    const token = begin();
     try {
       const res = await getTask(id);
+      if (!isCurrent(token)) return;
       if (res.task) {
         setTask(mapOfficeTaskToTask(res.task));
         if (res.timeline) setTimeline(res.timeline);
@@ -326,7 +270,7 @@ function useTaskOptimisticHelpers(
     } catch {
       /* swallow — next user action will retry */
     }
-  }, [id, setTask, setTimeline]);
+  }, [id, setTask, setTimeline, begin, isCurrent]);
   useOfficeRefetch(`task:${id}`, () => {
     void refetchTask();
   });
diff --git a/apps/web/components/task/simple/components/approval-action-bar.tsx b/apps/web/components/task/simple/components/approval-action-bar.tsx
index f90d963aad..dbc5ed2779 100644
--- a/apps/web/components/task/simple/components/approval-action-bar.tsx
+++ b/apps/web/components/task/simple/components/approval-action-bar.tsx
@@ -185,7 +185,7 @@ export function ApprovalActionBar({ task }: ApprovalActionBarProps) {
 // optimistic id with the real decision row id is performed implicitly
 // when `task:<id>` refetches via the WS handler. We keep the helper
 // available so future flows (e.g. a per-decision detail view) can map
-// the wire DTO consistently with mapDecisionDTO in page.tsx.
+// the wire DTO consistently with mapDecisionDTO in map-office-task.ts.
 export { dtoToDecision };
 
 type ApprovalCommentFormProps = {
diff --git a/apps/web/components/task/simple/components/property-row.tsx b/apps/web/components/task/simple/components/property-row.tsx
index 2e0d091985..3ccec80344 100644
--- a/apps/web/components/task/simple/components/property-row.tsx
+++ b/apps/web/components/task/simple/components/property-row.tsx
@@ -9,6 +9,8 @@ type PropertyRowProps = {
   valueClassName?: string;
   /** When true, align children to the top instead of centred. */
   alignStart?: boolean;
+  /** Test id placed on the value side, for E2E locators. */
+  testId?: string;
 };
 
 /**
@@ -22,6 +24,7 @@ export function PropertyRow({
   className,
   valueClassName,
   alignStart = false,
+  testId,
 }: PropertyRowProps) {
   return (
     <div
@@ -32,7 +35,9 @@ export function PropertyRow({
       )}
     >
       <span className="text-sm text-muted-foreground w-24 shrink-0 pt-0.5">{label}</span>
-      <div className={cn("text-sm text-right flex-1 min-w-0", valueClassName)}>{children}</div>
+      <div className={cn("text-sm text-right flex-1 min-w-0", valueClassName)} data-testid={testId}>
+        {children}
+      </div>
     </div>
   );
 }
diff --git a/apps/web/components/task/simple/task-properties.tsx b/apps/web/components/task/simple/task-properties.tsx
index 8740919525..222953ddd7 100644
--- a/apps/web/components/task/simple/task-properties.tsx
+++ b/apps/web/components/task/simple/task-properties.tsx
@@ -116,11 +116,18 @@ function TimelineSection({ task }: { task: Task }) {
   const { t } = useTranslation();
   const dateOrDash = (d?: string | null) =>
     d ? formatDate(d) : <span className="text-muted-foreground">--</span>;
+  const orDash = (v?: string | null) => (v ? v : <span className="text-muted-foreground">--</span>);
   return (
     <>
-      <PropertyRow label={t("task:createdBy")}>{task.createdBy}</PropertyRow>
-      <PropertyRow label={t("task:started")}>{dateOrDash(task.startedAt)}</PropertyRow>
-      <PropertyRow label={t("task:completed")}>{dateOrDash(task.completedAt)}</PropertyRow>
+      <PropertyRow label={t("task:createdBy")} testId="created-by-row">
+        {orDash(task.createdBy)}
+      </PropertyRow>
+      <PropertyRow label={t("task:started")} testId="started-row">
+        {dateOrDash(task.startedAt)}
+      </PropertyRow>
+      <PropertyRow label={t("task:completed")} testId="completed-row">
+        {dateOrDash(task.completedAt)}
+      </PropertyRow>
       <PropertyRow label={t("task:created")}>{formatDate(task.createdAt)}</PropertyRow>
       <PropertyRow label={t("task:updated")}>{formatRelativeTime(task.updatedAt)}</PropertyRow>
     </>
diff --git a/apps/web/e2e/tests/office/property-pickers.spec.ts b/apps/web/e2e/tests/office/property-pickers.spec.ts
index 9b4c686627..bbf9174416 100644
--- a/apps/web/e2e/tests/office/property-pickers.spec.ts
+++ b/apps/web/e2e/tests/office/property-pickers.spec.ts
@@ -1,5 +1,6 @@
 import { test, expect } from "../../fixtures/office-fixture";
 import type { Page } from "@playwright/test";
+import { waitForHttp } from "../../helpers/causal-waits";
 
 /**
  * E2E coverage for office task property pickers (status, priority,
@@ -360,4 +361,53 @@ test.describe("property pickers", () => {
       expect(after).toBe(before);
     }).toPass({ timeout: 5_000 });
   });
+
+  test("started and completed rows show timestamps after a todo -> in_progress -> done transition", async ({
+    testPage,
+    apiClient,
+    officeSeed,
+  }) => {
+    const task = await apiClient.createTask(officeSeed.workspaceId, "Picker Timeline Task", {
+      workflow_id: officeSeed.workflowId,
+    });
+
+    // startedAt/completedAt are derived server-side from the status-change
+    // timeline (see deriveTaskTimestamps in the backend) and delivered to
+    // the open page by the "office.task.status_changed" WS handler's
+    // per-task refetch (GET /api/v1/office/tasks/:id) — assert on that
+    // live-page refetch rather than a reload, so a regression of the
+    // refetch itself fails this test.
+    const taskDetailPath = new RegExp(`^/api/v1/office/tasks/${task.id}$`);
+
+    // gotoTaskPage only waits for the title heading, which can render before
+    // the sidebar's own render pass picks up the same task fetch; wait for
+    // the initial GET explicitly instead of racing the property rows against
+    // an unbudgeted paint (see e2e/helpers/causal-waits.ts).
+    const initialLoad = waitForHttp(testPage, "GET", taskDetailPath);
+    await gotoTaskPage(testPage, task.id, "Picker Timeline Task");
+    await initialLoad;
+
+    const startedRow = testPage.getByTestId("started-row");
+    const completedRow = testPage.getByTestId("completed-row");
+    await expect(startedRow).toHaveText("--");
+    await expect(completedRow).toHaveText("--");
+
+    const startedRefetch = waitForHttp(testPage, "GET", taskDetailPath);
+    await testPage.getByTestId("status-picker-trigger").click();
+    await testPage.getByTestId("status-picker-option-in_progress").click();
+    await expect(testPage.getByTestId("status-picker-trigger")).toContainText(/In Progress/i, {
+      timeout: 15_000,
+    });
+    await startedRefetch;
+    await expect(startedRow).not.toHaveText("--", { timeout: 5_000 });
+
+    const completedRefetch = waitForHttp(testPage, "GET", taskDetailPath);
+    await testPage.getByTestId("status-picker-trigger").click();
+    await testPage.getByTestId("status-picker-option-done").click();
+    await expect(testPage.getByTestId("status-picker-trigger")).toContainText(/Done/i, {
+      timeout: 15_000,
+    });
+    await completedRefetch;
+    await expect(completedRow).not.toHaveText("--", { timeout: 5_000 });
+  });
 });
diff --git a/apps/web/hooks/use-latest-only.test.ts b/apps/web/hooks/use-latest-only.test.ts
new file mode 100644
index 0000000000..2b11de39dc
--- /dev/null
+++ b/apps/web/hooks/use-latest-only.test.ts
@@ -0,0 +1,46 @@
+import { describe, expect, it } from "vitest";
+import { renderHook, act } from "@testing-library/react";
+import { useLatestOnly } from "./use-latest-only";
+
+// Regression for the Office task-detail refetch race: a WS trigger can
+// fire again before a prior GET resolves, and a slower earlier response
+// can arrive after a faster later one. useLatestOnly must let the caller
+// discard the stale response regardless of arrival order.
+describe("useLatestOnly", () => {
+  it("marks only the most recently begun token as current", () => {
+    const { result } = renderHook(() => useLatestOnly());
+
+    let tokenA = -1;
+    let tokenB = -1;
+    act(() => {
+      tokenA = result.current.begin();
+      tokenB = result.current.begin();
+    });
+
+    expect(result.current.isCurrent(tokenA)).toBe(false);
+    expect(result.current.isCurrent(tokenB)).toBe(true);
+  });
+
+  it("discards an earlier call's result when it resolves after a later call started", async () => {
+    const { result } = renderHook(() => useLatestOnly());
+    const applied: string[] = [];
+
+    // Simulates the exact race: call A starts, call B starts before A
+    // resolves, then A's (stale) response arrives followed by B's.
+    const tokenA = result.current.begin();
+    const tokenB = result.current.begin();
+
+    if (result.current.isCurrent(tokenA)) applied.push("A");
+    if (result.current.isCurrent(tokenB)) applied.push("B");
+
+    expect(applied).toEqual(["B"]);
+  });
+
+  it("accepts a call's result when no newer call has started since", () => {
+    const { result } = renderHook(() => useLatestOnly());
+
+    const token = result.current.begin();
+
+    expect(result.current.isCurrent(token)).toBe(true);
+  });
+});
diff --git a/apps/web/hooks/use-latest-only.ts b/apps/web/hooks/use-latest-only.ts
new file mode 100644
index 0000000000..2398299893
--- /dev/null
+++ b/apps/web/hooks/use-latest-only.ts
@@ -0,0 +1,16 @@
+import { useCallback, useRef } from "react";
+
+/**
+ * Ordering guard for async work that can overlap (a WS trigger firing
+ * again before a prior GET resolves, ordinary network jitter). `begin()`
+ * stamps a new generation before starting the work; `isCurrent(token)`
+ * reports whether no newer call has started since — even if this call's
+ * response arrives after a more recent call's response, so callers can
+ * discard it instead of overwriting fresher state with stale data.
+ */
+export function useLatestOnly() {
+  const generationRef = useRef(0);
+  const begin = useCallback(() => ++generationRef.current, []);
+  const isCurrent = useCallback((token: number) => token === generationRef.current, []);
+  return { begin, isCurrent };
+}
diff --git a/apps/web/hooks/use-office-refetch.test.ts b/apps/web/hooks/use-office-refetch.test.ts
new file mode 100644
index 0000000000..0cdd5b603a
--- /dev/null
+++ b/apps/web/hooks/use-office-refetch.test.ts
@@ -0,0 +1,144 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { cleanup, renderHook } from "@testing-library/react";
+
+let storeState: { office: { refetchTriggers: Record<string, number> } } = {
+  office: { refetchTriggers: {} },
+};
+
+vi.mock("@/components/state-provider", () => ({
+  useAppStore: (selector: (state: typeof storeState) => unknown) => selector(storeState),
+}));
+
+import { useOfficeRefetch } from "./use-office-refetch";
+
+function bump(type: string) {
+  const triggers = storeState.office.refetchTriggers;
+  storeState = {
+    office: { refetchTriggers: { ...triggers, [type]: (triggers[type] ?? 0) + 1 } },
+  };
+}
+
+describe("useOfficeRefetch", () => {
+  beforeEach(() => {
+    storeState = { office: { refetchTriggers: {} } };
+  });
+
+  afterEach(() => {
+    cleanup();
+  });
+
+  it("does not fire on mount when no trigger has fired for this type", () => {
+    const onRefetch = vi.fn();
+    renderHook(() => useOfficeRefetch("dashboard", onRefetch));
+    expect(onRefetch).not.toHaveBeenCalled();
+  });
+
+  it("fires when its exact type is bumped", () => {
+    const onRefetch = vi.fn();
+    const { rerender } = renderHook(() => useOfficeRefetch("dashboard", onRefetch));
+
+    bump("dashboard");
+    rerender();
+
+    expect(onRefetch).toHaveBeenCalledTimes(1);
+  });
+
+  it("fires on a prefix match (comments: matches comments:task-123)", () => {
+    const onRefetch = vi.fn();
+    const { rerender } = renderHook(() => useOfficeRefetch("comments", onRefetch));
+
+    bump("comments:task-123");
+    rerender();
+
+    expect(onRefetch).toHaveBeenCalledTimes(1);
+  });
+
+  it("does not fire for an unrelated type", () => {
+    const onRefetch = vi.fn();
+    const { rerender } = renderHook(() => useOfficeRefetch("dashboard", onRefetch));
+
+    bump("tasks");
+    rerender();
+
+    expect(onRefetch).not.toHaveBeenCalled();
+  });
+
+  it("does not re-fire on a render that doesn't bump its type", () => {
+    const onRefetch = vi.fn();
+    const { rerender } = renderHook(() => useOfficeRefetch("dashboard", onRefetch));
+
+    bump("dashboard");
+    rerender();
+    rerender();
+    rerender();
+
+    expect(onRefetch).toHaveBeenCalledTimes(1);
+  });
+
+  // Regression test: a single WS handler often bumps several distinct trigger
+  // types in one synchronous call (e.g. `task:${id}` then `dashboard`), which
+  // React coalesces into a single render. A shared "last trigger" store field
+  // would overwrite itself on every bump, so only the final type's subscriber
+  // would ever observe a change — every other type silently never refetches.
+  // Per-type counters must let every matching subscriber see its own bump
+  // even when several types were bumped before React ever renders.
+  it("lets every subscriber observe its own bump when multiple types are bumped in the same tick", () => {
+    const onTaskRefetch = vi.fn();
+    const onDashboardRefetch = vi.fn();
+    const { rerender: rerenderTask } = renderHook(() =>
+      useOfficeRefetch("task:t-1", onTaskRefetch),
+    );
+    const { rerender: rerenderDashboard } = renderHook(() =>
+      useOfficeRefetch("dashboard", onDashboardRefetch),
+    );
+
+    // Simulate a WS handler firing both triggers before either hook re-renders.
+    bump("task:t-1");
+    bump("dashboard");
+    rerenderTask();
+    rerenderDashboard();
+
+    expect(onTaskRefetch).toHaveBeenCalledTimes(1);
+    expect(onDashboardRefetch).toHaveBeenCalledTimes(1);
+  });
+
+  // Regression test: a prefix subscriber watches several sub-keys under one
+  // triggerType (e.g. "comments" matches "comments:task-A" and
+  // "comments:task-B"). A single scalar "last seen" value would let a bump
+  // on one sub-key mask a later bump on a sibling sub-key whenever the
+  // sibling's counter is lower than the max already observed. Per-key
+  // tracking must let each sub-key's bump fire independently.
+  it("still fires for a sub-key bump after a higher-numbered sibling sub-key already fired", () => {
+    const onRefetch = vi.fn();
+    const { rerender } = renderHook(() => useOfficeRefetch("comments", onRefetch));
+
+    // task-B races ahead first, bumped three times.
+    bump("comments:task-B");
+    bump("comments:task-B");
+    bump("comments:task-B");
+    rerender();
+    expect(onRefetch).toHaveBeenCalledTimes(1);
+
+    // task-A's first bump (counter 1) is lower than task-B's counter (3), so
+    // a scalar "max seen" comparison would swallow it.
+    bump("comments:task-A");
+    rerender();
+
+    expect(onRefetch).toHaveBeenCalledTimes(2);
+  });
+
+  it("uses the latest callback without re-firing when only the callback changes", () => {
+    const first = vi.fn();
+    const second = vi.fn();
+    const { rerender } = renderHook(({ cb }) => useOfficeRefetch("dashboard", cb), {
+      initialProps: { cb: first },
+    });
+
+    rerender({ cb: second });
+    bump("dashboard");
+    rerender({ cb: second });
+
+    expect(first).not.toHaveBeenCalled();
+    expect(second).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/apps/web/hooks/use-office-refetch.ts b/apps/web/hooks/use-office-refetch.ts
index 4afcb0654b..a72e32f208 100644
--- a/apps/web/hooks/use-office-refetch.ts
+++ b/apps/web/hooks/use-office-refetch.ts
@@ -1,26 +1,48 @@
 import { useEffect, useLayoutEffect, useRef } from "react";
 import { useAppStore } from "@/components/state-provider";
 
+// Any real counter the store can hold is >= 1, so 0 reliably "looks bumped"
+// on the very first observed value and "looks unbumped" otherwise — see
+// use-session-commits.ts for the same sentinel pattern.
+const REFETCH_TRIGGER_INIT = 0;
+
 /**
- * Calls `onRefetch` when the office refetch trigger matches `triggerType`.
+ * Calls `onRefetch` when a matching office refetch trigger fires.
  * Supports exact match ("dashboard") or prefix match ("comments:" matches "comments:task-123").
  *
+ * Triggers are per-type counters (`office.refetchTriggers`), not a single
+ * "last trigger" value: a WS handler often bumps several distinct types in
+ * one synchronous call (e.g. `task:${id}` then `dashboard`), and React
+ * coalesces those into one render, so a shared last-value field would only
+ * ever be observable by the final type's subscribers.
+ *
  * @param triggerType - The trigger type to watch for (e.g. "dashboard", "tasks", "comments")
  * @param onRefetch - Callback invoked when a matching trigger fires
  */
 export function useOfficeRefetch(triggerType: string, onRefetch: () => void) {
-  const trigger = useAppStore((s) => s.office.refetchTrigger);
+  const triggers = useAppStore((s) => s.office.refetchTriggers);
   const callbackRef = useRef(onRefetch);
   // Update ref in a layout effect to avoid mutating during render
   useLayoutEffect(() => {
     callbackRef.current = onRefetch;
   });
 
+  // Tracks the highest counter we've already acted on, per matching key, so
+  // a bump triggers exactly one refetch rather than re-firing on every
+  // render. A single scalar here would let a bump on one sub-key (e.g.
+  // "comments:task-B") mask a later bump on a sibling sub-key ("comments:
+  // task-A") whenever the sibling's counter happened to be lower.
+  const lastSeenRef = useRef<Record<string, number>>({});
+
   useEffect(() => {
-    if (!trigger) return;
-    const matches = trigger.type === triggerType || trigger.type.startsWith(triggerType + ":");
-    if (matches) {
-      callbackRef.current();
+    let fire = false;
+    for (const [type, seq] of Object.entries(triggers)) {
+      if (type !== triggerType && !type.startsWith(triggerType + ":")) continue;
+      if (seq > (lastSeenRef.current[type] ?? REFETCH_TRIGGER_INIT)) {
+        lastSeenRef.current[type] = seq;
+        fire = true;
+      }
     }
-  }, [trigger, triggerType]);
+    if (fire) callbackRef.current();
+  }, [triggers, triggerType]);
 }
diff --git a/apps/web/lib/state/slices/office/office-slice.ts b/apps/web/lib/state/slices/office/office-slice.ts
index ff12719b60..f8a32d1880 100644
--- a/apps/web/lib/state/slices/office/office-slice.ts
+++ b/apps/web/lib/state/slices/office/office-slice.ts
@@ -42,7 +42,7 @@ export const defaultOfficeState: OfficeSliceState = {
     },
     meta: null,
     isLoading: false,
-    refetchTrigger: null,
+    refetchTriggers: {},
     routing: {
       byWorkspace: {},
       knownProviders: [],
@@ -272,7 +272,8 @@ function createMiscActions(set: SetFn) {
       }),
     setOfficeRefetchTrigger: (type: string) =>
       set((draft) => {
-        draft.office.refetchTrigger = { type, timestamp: Date.now() };
+        const prev = draft.office.refetchTriggers[type] ?? 0;
+        draft.office.refetchTriggers[type] = prev + 1;
       }),
   };
 }
diff --git a/apps/web/lib/state/slices/office/office-task-type.ts b/apps/web/lib/state/slices/office/office-task-type.ts
new file mode 100644
index 0000000000..413be86276
--- /dev/null
+++ b/apps/web/lib/state/slices/office/office-task-type.ts
@@ -0,0 +1,32 @@
+import type { OfficeTaskPriority, OfficeTaskStatus, TaskLabel } from "./types";
+
+export type OfficeTask = {
+  id: string;
+  workspaceId: string;
+  identifier: string;
+  title: string;
+  description?: string;
+  status: OfficeTaskStatus;
+  // Pre-normalization backend value (e.g. "SCHEDULING"); read only for a raw
+  // sub-state the canonical union erases (ExecutionIndicator's "Live" dot).
+  rawStatus?: string;
+  priority: OfficeTaskPriority;
+  parentId?: string;
+  projectId?: string;
+  assigneeAgentProfileId?: string;
+  labels?: TaskLabel[] | string[];
+  blockedBy?: string[];
+  children?: OfficeTask[];
+  executionPolicy?: string;
+  executionState?: string;
+  // Derived best-effort from the status-change activity log; not a column.
+  startedAt?: string;
+  completedAt?: string;
+  createdAt: string;
+  updatedAt: string;
+  // True when the task lives in a kandev-managed system workflow
+  // (today: standing coordination; future: routine-fired). The Tasks
+  // UI renders a "System" badge for these when the dev toggle reveals
+  // them.
+  isSystem?: boolean;
+};
diff --git a/apps/web/lib/state/slices/office/types.ts b/apps/web/lib/state/slices/office/types.ts
index 23e6af110f..9e41206aab 100644
--- a/apps/web/lib/state/slices/office/types.ts
+++ b/apps/web/lib/state/slices/office/types.ts
@@ -254,33 +254,8 @@ export type TaskLabel = {
   color: string;
 };
 
-export type OfficeTask = {
-  id: string;
-  workspaceId: string;
-  identifier: string;
-  title: string;
-  description?: string;
-  status: OfficeTaskStatus;
-  // Pre-normalization backend value (e.g. "SCHEDULING"); read only for a raw
-  // sub-state the canonical union erases (ExecutionIndicator's "Live" dot).
-  rawStatus?: string;
-  priority: OfficeTaskPriority;
-  parentId?: string;
-  projectId?: string;
-  assigneeAgentProfileId?: string;
-  labels?: TaskLabel[] | string[];
-  blockedBy?: string[];
-  children?: OfficeTask[];
-  executionPolicy?: string;
-  executionState?: string;
-  createdAt: string;
-  updatedAt: string;
-  // True when the task lives in a kandev-managed system workflow
-  // (today: standing coordination; future: routine-fired). The Tasks
-  // UI renders a "System" badge for these when the dev toggle reveals
-  // them.
-  isSystem?: boolean;
-};
+import type { OfficeTask } from "./office-task-type";
+export type { OfficeTask } from "./office-task-type";
 
 export type TaskFilterState = {
   statuses: OfficeTaskStatus[];
@@ -523,11 +498,6 @@ import type {
 
 // --- Slice state & actions ---
 
-export type OfficeRefetchTrigger = {
-  type: string;
-  timestamp: number;
-};
-
 /**
  * Office collections that belong to one workspace, stored per workspace id
  * rather than as a single current value.
@@ -562,7 +532,12 @@ export type OfficeSliceState = {
     tasks: TasksState;
     meta: OfficeMeta | null;
     isLoading: boolean;
-    refetchTrigger: OfficeRefetchTrigger | null;
+    // Per-type counters rather than one "last trigger" value: a single WS
+    // handler often fires several distinct types in the same synchronous
+    // call (e.g. `task:${id}` then `dashboard`), and React/Zustand coalesce
+    // those into one render, so a shared last-value field would only ever
+    // let the final type's subscribers see a change. See useOfficeRefetch.
+    refetchTriggers: Record<string, number>;
     routing: RoutingState;
     providerHealth: ProviderHealthSliceState;
     runAttempts: RunAttemptsState;
diff --git a/apps/web/lib/ws/handlers/office.test.ts b/apps/web/lib/ws/handlers/office.test.ts
index 6c469b77da..53b47fbe4b 100644
--- a/apps/web/lib/ws/handlers/office.test.ts
+++ b/apps/web/lib/ws/handlers/office.test.ts
@@ -134,7 +134,7 @@ describe("office WS handler — workspace filter", () => {
   });
 });
 
-describe("office WS handler — task field updates delegate to patchTaskInStore", () => {
+describe("office WS handler — task field updates", () => {
   beforeEach(() => {
     vi.clearAllMocks();
   });
@@ -156,7 +156,7 @@ describe("office WS handler — task field updates delegate to patchTaskInStore"
     );
   });
 
-  it("refreshes tasks for a producer task.moved payload without a status", () => {
+  it("refreshes the task detail and activity for a producer task.moved payload without a status", () => {
     const { store, patchTaskInStore, setOfficeRefetchTrigger } = makeStore(ACTIVE_WS);
     const handlers = registerOfficeHandlers(store);
     const handler = handlers["office.task.moved"]!;
@@ -176,6 +176,8 @@ describe("office WS handler — task field updates delegate to patchTaskInStore"
     expect(patchTaskInStore).not.toHaveBeenCalled();
     expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("tasks");
     expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("dashboard");
+    expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("task:t-1");
+    expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("activity");
   });
 
   it("passes the raw new_status through on office.task.status_changed", () => {
@@ -191,6 +193,37 @@ describe("office WS handler — task field updates delegate to patchTaskInStore"
 
     expect(patchTaskInStore).toHaveBeenCalledWith("t-1", { status: "CREATED" });
   });
+
+  it("refreshes the per-task DTO and dashboard on office.task.status_changed", () => {
+    const { store, setOfficeRefetchTrigger } = makeStore(ACTIVE_WS);
+    const handlers = registerOfficeHandlers(store);
+    const handler = handlers["office.task.status_changed"]!;
+
+    handler({
+      type: "notification",
+      action: "office.task.status_changed",
+      payload: { workspace_id: ACTIVE_WS, task_id: "t-42", new_status: "done" },
+    } as Parameters<typeof handler>[0]);
+
+    expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("task:t-42");
+    expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("dashboard");
+  });
+
+  it("refreshes the per-task DTO, dashboard, and activity on office.task.moved", () => {
+    const { store, setOfficeRefetchTrigger } = makeStore(ACTIVE_WS);
+    const handlers = registerOfficeHandlers(store);
+    const handler = handlers["office.task.moved"]!;
+
+    handler({
+      type: "notification",
+      action: "office.task.moved",
+      payload: { workspace_id: ACTIVE_WS, task_id: "t-99", new_status: "in_progress" },
+    } as Parameters<typeof handler>[0]);
+
+    expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("task:t-99");
+    expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("dashboard");
+    expect(setOfficeRefetchTrigger).toHaveBeenCalledWith("activity");
+  });
 });
 
 describe("office WS handler — approval flow events", () => {
diff --git a/apps/web/lib/ws/handlers/office.ts b/apps/web/lib/ws/handlers/office.ts
index ee315a1426..f484f0ace7 100644
--- a/apps/web/lib/ws/handlers/office.ts
+++ b/apps/web/lib/ws/handlers/office.ts
@@ -79,12 +79,20 @@ function buildTaskHandlers(
       if (!isCurrentWorkspace(p)) return;
       const taskId = (p.task_id ?? p.id) as string | undefined;
       const newStatus = p.new_status as string | undefined;
-      if (!taskId || !newStatus) {
+      if (!taskId) {
         triggerRefetch("tasks");
         triggerRefetch("dashboard");
         return;
       }
-      updateTaskStatus(taskId, { status: newStatus as OfficeTaskStatus });
+      // The task service publishes task.moved without new_status. Keep the
+      // direct patch when a producer provides one, but always refresh the
+      // detail and activity projections for a known task.
+      if (newStatus) {
+        updateTaskStatus(taskId, { status: newStatus as OfficeTaskStatus });
+      } else {
+        triggerRefetch("tasks");
+      }
+      triggerRefetch(`task:${taskId}`);
       triggerRefetch("dashboard");
       triggerRefetch("activity");
     },
@@ -99,6 +107,7 @@ function buildTaskHandlers(
         return;
       }
       updateTaskStatus(taskId, { status: newStatus as OfficeTaskStatus });
+      triggerRefetch(`task:${taskId}`);
       triggerRefetch("dashboard");
     },