diff --git a/src/benchmark.ts b/src/benchmark.ts
index a9b2cc5..9eb1523 100644
--- a/src/benchmark.ts
+++ b/src/benchmark.ts
@@ -24,6 +24,41 @@ export function computeStats(values: number[]): Stats {
   };
 }
 
+/**
+ * Sweep-cleanup: list all sandboxes for a provider and destroy any that are still alive.
+ * This catches anything the per-iteration finally blocks missed (timeouts, silent failures, etc).
+ */
+export async function cleanupAllSandboxes(compute: any, providerName: string): Promise<void> {
+  try {
+    const sandboxes = await Promise.race([
+      compute.sandbox.list(),
+      new Promise<any[]>((_, reject) => setTimeout(() => reject(new Error('List timeout')), 30_000)),
+    ]);
+
+    if (!sandboxes || sandboxes.length === 0) return;
+
+    console.log(`  [cleanup] ${providerName}: found ${sandboxes.length} lingering sandbox(es), destroying...`);
+
+    const destroyResults = await Promise.allSettled(
+      sandboxes.map((s: any) =>
+        Promise.race([
+          s.destroy(),
+          new Promise((_, reject) => setTimeout(() => reject(new Error('Destroy timeout')), 15_000)),
+        ])
+      )
+    );
+
+    const failed = destroyResults.filter(r => r.status === 'rejected');
+    if (failed.length > 0) {
+      console.warn(`  [cleanup] ${providerName}: ${failed.length}/${sandboxes.length} destroy(s) failed`);
+    } else {
+      console.log(`  [cleanup] ${providerName}: all ${sandboxes.length} sandbox(es) destroyed`);
+    }
+  } catch (err) {
+    console.warn(`  [cleanup] ${providerName}: sweep failed: ${err instanceof Error ? err.message : String(err)}`);
+  }
+}
+
 export async function runBenchmark(config: ProviderConfig): Promise<BenchmarkResult> {
   const { name, iterations = 100, timeout = 120_000, requiredEnvVars, sandboxOptions } = config;
 
diff --git a/src/run.ts b/src/run.ts
index 90035af..f09f01e 100644
--- a/src/run.ts
+++ b/src/run.ts
@@ -2,7 +2,7 @@ import fs from 'fs';
 import { config } from 'dotenv';
 import path from 'path';
 import { fileURLToPath } from 'url';
-import { runBenchmark } from './benchmark.js';
+import { runBenchmark, cleanupAllSandboxes } from './benchmark.js';
 import { runConcurrentBenchmark } from './concurrent.js';
 import { runStaggeredBenchmark } from './staggered.js';
 import { printResultsTable, writeResultsJson } from './table.js';
@@ -61,6 +61,8 @@ async function runMode(mode: BenchmarkMode, toRun: typeof providers): Promise<vo
   const results: BenchmarkResult[] = [];
 
   for (const providerConfig of toRun) {
+    const compute = providerConfig.createCompute();
+
     switch (mode) {
       case 'sequential': {
         const result = await runBenchmark({ ...providerConfig, iterations });
@@ -83,6 +85,9 @@ async function runMode(mode: BenchmarkMode, toRun: typeof providers): Promise<vo
         break;
       }
     }
+
+    // Sweep-cleanup: destroy any sandboxes still alive after the benchmark
+    await cleanupAllSandboxes(compute, providerConfig.name);
   }
 
   // Compute composite scores