diff --git a/frontend/src/app/pages/Dashboard/hooks/lifecycle/useDashboardLifecycle.ts b/frontend/src/app/pages/Dashboard/hooks/lifecycle/useDashboardLifecycle.ts
index 2df58b93..8fbff97c 100644
--- a/frontend/src/app/pages/Dashboard/hooks/lifecycle/useDashboardLifecycle.ts
+++ b/frontend/src/app/pages/Dashboard/hooks/lifecycle/useDashboardLifecycle.ts
@@ -24,7 +24,7 @@ import {
 } from '@/shared/state/dashboardLayoutSlice';
 import { fetchOutputs, type Output } from '@/shared/state/outputsSlice';
 import { generateDashboardName } from '@/shared/state/dashboardsSlice';
-import { isUserLaunchedSession } from '@/shared/state/isUserLaunchedSession';
+import { deservesCanvasCard } from '@/shared/state/isUserLaunchedSession';
 import { REVEAL_MIN_ZOOM } from '../../canvas/revealZoom';
 import { fetchWorkflows, fetchAllRuns, fetchActiveRuns } from '@/shared/state/workflowsSlice';
 import { fetchMissedRuns } from '@/shared/state/missedRunsSlice';
@@ -326,7 +326,7 @@ export function useDashboardLifecycle({
   useEffect(() => {
     if (!layoutInitialized) return;
     const dashboardSessionIds = Object.values(sessions)
-      .filter((s) => s.dashboard_id === dashboardId && isUserLaunchedSession(s))
+      .filter((s) => s.dashboard_id === dashboardId && deservesCanvasCard(s))
       .map((s) => s.id);
     const liveIds = dashboardSessionIds.sort().join(',');
     if (liveIds === prevSessionIdsRef.current) return;
diff --git a/frontend/src/shared/state/deservesCanvasCard.test.ts b/frontend/src/shared/state/deservesCanvasCard.test.ts
new file mode 100644
index 00000000..46cc1cd8
--- /dev/null
+++ b/frontend/src/shared/state/deservesCanvasCard.test.ts
@@ -0,0 +1,44 @@
+// Run: node --test frontend/src/shared/state/deservesCanvasCard.test.ts
+//
+// ENG-256. A workflow run was denied a canvas card, and the browser-docking path is gated on the
+// parent card existing, so its browsers spawned as loose windows nothing owned and nothing tore
+// down. ENG-248/249/250 were all symptoms of that one missing object. The rule now: a run gets a
+// real card while it is running, and loses it when it stops, so a nightly workflow does not leave a
+// card behind every night.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { deservesCanvasCard, isUserLaunchedSession } from './isUserLaunchedSession.ts';
+
+const chat = { mode: 'agent', status: 'completed' };
+const run = (status: string) => ({ mode: 'agent', status, workflow_run_id: 'run-1' });
+
+test('an ordinary chat always has a card, running or not', () => {
+  assert.equal(deservesCanvasCard(chat), true);
+  assert.equal(deservesCanvasCard({ mode: 'agent', status: 'running' }), true);
+});
+
+test('a workflow run has a card while it works', () => {
+  assert.equal(deservesCanvasCard(run('running')), true);
+  assert.equal(deservesCanvasCard(run('waiting_approval')), true);
+});
+
+test('a workflow run loses its card the moment it stops', () => {
+  for (const s of ['completed', 'failed', 'stopped', 'error', '']) {
+    assert.equal(deservesCanvasCard(run(s)), false, `status ${s || '(empty)'}`);
+  }
+  assert.equal(deservesCanvasCard({ mode: 'agent', workflow_run_id: 'run-1' }), false, 'no status at all');
+});
+
+test('plumbing chats never get a card, however they look', () => {
+  for (const mode of ['browser-agent', 'invoked-agent', 'sub-agent']) {
+    assert.equal(deservesCanvasCard({ mode, status: 'running' }), false, mode);
+  }
+  assert.equal(deservesCanvasCard({ mode: 'agent', status: 'running', workflow_edit_id: 'e1' }), false);
+});
+
+test('notifications are still a separate question from cards', () => {
+  // A running workflow now earns a CARD but must not start earning notifications: nobody asked for
+  // a ping every time a scheduled job fires.
+  assert.equal(deservesCanvasCard(run('running')), true);
+  assert.equal(isUserLaunchedSession(run('running')), false);
+});
diff --git a/frontend/src/shared/state/isUserLaunchedSession.ts b/frontend/src/shared/state/isUserLaunchedSession.ts
index 20c595cf..3e1e6e70 100644
--- a/frontend/src/shared/state/isUserLaunchedSession.ts
+++ b/frontend/src/shared/state/isUserLaunchedSession.ts
@@ -8,7 +8,23 @@ export interface SessionOrigin {
   workflow_edit_id?: string | null;
 }
 
-/** True for a chat the user started themselves, which is the only kind that earns a card or a notification. */
+/** A run that is still working, so its card is worth having on screen. */
+const LIVE_STATUSES: ReadonlySet<string> = new Set(['running', 'waiting_approval']);
+
+/** True for a chat the user started themselves, which is the only kind that earns a notification. */
 export function isUserLaunchedSession(session: SessionOrigin): boolean {
   return !session.workflow_run_id && !session.workflow_edit_id && !PLUMBING_MODES.has(session.mode);
 }
+
+/** True for a session that should have a card on the canvas right now.
+ *
+ * A workflow run earns one WHILE IT RUNS. Denying it a card is what made its browsers spawn as loose
+ * canvas windows that nothing owned and nothing tore down (ENG-248/249/250 were all symptoms of it):
+ * the dock path is gated on the parent card existing, so no card meant no owner. Give the run a card
+ * and the existing inline-dock plus despawn logic applies to it unchanged. The card goes when the run
+ * stops, or a nightly workflow would leave one behind every single night.
+ */
+export function deservesCanvasCard(session: SessionOrigin & { status?: string }): boolean {
+  if (isUserLaunchedSession(session)) return true;
+  return !!session.workflow_run_id && LIVE_STATUSES.has(session.status ?? '');
+}