diff --git a/frontend/src/lib/components/sessions/latestWins.test.ts b/frontend/src/lib/components/sessions/latestWins.test.ts
index cf7686caf9..9ab3c81b95 100644
--- a/frontend/src/lib/components/sessions/latestWins.test.ts
+++ b/frontend/src/lib/components/sessions/latestWins.test.ts
@@ -72,10 +72,14 @@ describe('createLatestWins', () => {
 			q.run('s', () => {
 				throw new Error('boom')
 			})
+			// Let the throwing task actually run before the next one queues, or it
+			// is skipped as superseded and the failure never happens.
+			await tick()
 			q.run('s', () => {
 				ran.push('after')
 			})
 			await tick()
+			expect(errorSpy).toHaveBeenCalled()
 			expect(ran).toEqual(['after'])
 		} finally {
 			errorSpy.mockRestore()
diff --git a/frontend/src/lib/components/sessions/sessionRuntime.svelte.ts b/frontend/src/lib/components/sessions/sessionRuntime.svelte.ts
index 0e3afded1f..97857d15a4 100644
--- a/frontend/src/lib/components/sessions/sessionRuntime.svelte.ts
+++ b/frontend/src/lib/components/sessions/sessionRuntime.svelte.ts
@@ -1189,8 +1189,11 @@ async function applyTurnEnd(
 		caughtUp = true
 	} catch (e) {
 		// A read that threw leaves the same mismatched pair an 'unavailable' one
-		// does, so it earns the same answer rather than a silent release.
+		// does, so it earns the same answer rather than a silent release — the
+		// supersession check included, or the retry would carry this task's stale
+		// chat id past the newer catch-up that owns the gate now.
 		console.error('sessionRuntime: catch-up failed', e)
+		if (superseded()) return
 		scheduleCatchUpRetry(sessionId, chatId, attempt)
 	} finally {
 		if (caughtUp) noteCaughtUp(sessionId)