diff --git a/apps/electron-backend-e2e/src/performance/database-worker-post-gc-report.spec.ts b/apps/electron-backend-e2e/src/performance/database-worker-post-gc-report.spec.ts
new file mode 100644
index 000000000..bdcb900ac
--- /dev/null
+++ b/apps/electron-backend-e2e/src/performance/database-worker-post-gc-report.spec.ts
@@ -0,0 +1,107 @@
+/* eslint-disable playwright/expect-expect -- These are Node assertion-based performance contract tests. */
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import {
+    type CancellationBenchmarkManifest,
+    type CancellationIterationResult,
+    PERFORMANCE_ITERATION_KIND,
+    PERFORMANCE_WORKER_KIND,
+    type WorkerCaptureMetrics,
+} from './m3u-refresh-cancellation-contract';
+import { createCancellationBenchmarkSummary } from './m3u-refresh-cancellation-report';
+
+function databaseWorker(
+    postGcHeapUsedBytes: number | null,
+    postGcHeapUnavailableReason: string | null
+): WorkerCaptureMetrics {
+    return {
+        kind: PERFORMANCE_WORKER_KIND.DATABASE,
+        peakExternalBytes: 0,
+        peakHeapUsedBytes: 0,
+        postGcHeapUnavailableReason,
+        postGcHeapUsedBytes,
+        requests: [],
+    } as unknown as WorkerCaptureMetrics;
+}
+
+function measuredIteration(
+    workers: readonly WorkerCaptureMetrics[]
+): CancellationIterationResult {
+    return {
+        cancellationEffectObserved: true,
+        kind: PERFORMANCE_ITERATION_KIND.MEASURED,
+        main: {
+            eventLoopDelay: { maxMs: 0, p95Ms: 0, p99Ms: 0 },
+            eventLoopUtilization: null,
+            memory: {
+                peakHeapUsedBytes: 0,
+                peakRssBytes: 0,
+                postGcHeapUsedBytes: null,
+                postGcRssBytes: null,
+            },
+            rendererWindow: {
+                responsiveEvents: 0,
+                rss: {
+                    identity: {
+                        creationTime: 1_721_234_567_890,
+                        pid: 42,
+                    },
+                    missingSampleCount: 0,
+                    peakRssBytes: 2_048,
+                    unavailableReason: null,
+                    validSampleCount: 1,
+                },
+                unresponsiveEvents: 0,
+                windowIdentity: {
+                    browserWindowId: 7,
+                    webContentsId: 11,
+                },
+            },
+            workers,
+        },
+        phases: {},
+        renderer: {
+            peakHeapUsedBytes: 0,
+            postGcHeapUsedBytes: null,
+            probe: {
+                frameGapsMs: [],
+                heartbeatDelaysMs: [],
+                longTasksMs: [],
+            },
+        },
+        runId: 'measured',
+    } as unknown as CancellationIterationResult;
+}
+
+test('summary includes every database isolate instead of silently taking the first', () => {
+    const unavailable = databaseWorker(null, 'post-gc-probe-invalid-response');
+    const summary = createCancellationBenchmarkSummary(
+        {} as CancellationBenchmarkManifest,
+        [
+            measuredIteration([
+                databaseWorker(100, null),
+                databaseWorker(300, null),
+                unavailable,
+            ]),
+        ]
+    );
+
+    assert.deepEqual(summary.measured.databaseWorkerPostGcHeapBytes, {
+        count: 2,
+        max: 300,
+        mean: 200,
+        median: 200,
+        min: 100,
+        p95: 290,
+        p99: 298,
+    });
+    assert.equal(
+        (
+            summary.iterations[0]?.main.workers[2] as WorkerCaptureMetrics & {
+                readonly postGcHeapUnavailableReason: string | null;
+            }
+        )?.postGcHeapUnavailableReason,
+        'post-gc-probe-invalid-response'
+    );
+});
diff --git a/apps/electron-backend-e2e/src/performance/m3u-refresh-cancellation-report.ts b/apps/electron-backend-e2e/src/performance/m3u-refresh-cancellation-report.ts
index 9eece7fc6..5d5542024 100644
--- a/apps/electron-backend-e2e/src/performance/m3u-refresh-cancellation-report.ts
+++ b/apps/electron-backend-e2e/src/performance/m3u-refresh-cancellation-report.ts
@@ -57,12 +57,11 @@ export function createCancellationBenchmarkSummary(
         select: (worker: MainCaptureMetrics['workers'][number]) => number | null
     ): NumericDistribution =>
         summarizeNumbers(
-            measured.map((iteration) => {
-                const worker = iteration.main.workers.find(
-                    (candidate) => candidate.kind === kind
-                );
-                return worker ? select(worker) : null;
-            })
+            measured.flatMap((iteration) =>
+                iteration.main.workers
+                    .filter((worker) => worker.kind === kind)
+                    .map((worker) => select(worker))
+            )
         );
     const workerRequestMetric = (
         kind: PerformanceWorkerKind,