diff --git a/.github/workflows/process-cleanup-stress.yml b/.github/workflows/process-cleanup-stress.yml
new file mode 100644
index 000000000..e9ca57ffe
--- /dev/null
+++ b/.github/workflows/process-cleanup-stress.yml
@@ -0,0 +1,33 @@
+name: Process cleanup stress
+
+on:
+  pull_request:
+    paths:
+      - ".github/workflows/process-cleanup-stress.yml"
+      - "scripts/verify-process-cleanup-stress.mjs"
+      - "src/application/ProcessCaptureLifecycle.ts"
+      - "src/application/ProcessHarness.ts"
+      - "src/application/ProcessOwnership.ts"
+      - "tests/fixtures/processFidelity.mjs"
+      - "package.json"
+      - "package-lock.json"
+  schedule:
+    - cron: "17 4 * * 1"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  real-forkpty-cleanup:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: npm
+      - run: npm ci
+      - run: npm run verify:process:stress
diff --git a/package.json b/package.json
index e3a3148a4..f2121defd 100644
--- a/package.json
+++ b/package.json
@@ -71,6 +71,7 @@
     "typecheck": "tsc --noEmit",
     "verify:hopper": "npm run build && node scripts/verify-real-hopper.mjs",
     "verify:browser": "npm run build && node scripts/verify-real-browser.mjs",
+    "verify:process:stress": "npm run build && node scripts/verify-process-cleanup-stress.mjs",
     "verify:hopper:linux": "npm run build && node scripts/verify-real-hopper-linux.mjs",
     "verify:setup:linux": "npm run build && node scripts/verify-linux-setup-e2e.mjs",
     "build:fixtures": "node scripts/build-conformance-fixtures.mjs",
diff --git a/scripts/verify-process-cleanup-stress.mjs b/scripts/verify-process-cleanup-stress.mjs
new file mode 100644
index 000000000..684b04903
--- /dev/null
+++ b/scripts/verify-process-cleanup-stress.mjs
@@ -0,0 +1,77 @@
+#!/usr/bin/env node
+
+import { execFile } from "node:child_process";
+import { dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+import { promisify } from "node:util";
+
+import {
+  captureProcessScenario,
+  probeProcessCaptureCapability,
+} from "../dist/application/ProcessHarness.js";
+import { parseProcessScenario } from "../dist/domain/processScenario.js";
+
+const execFileAsync = promisify(execFile);
+const fixture = fileURLToPath(
+  new URL("../tests/fixtures/processFidelity.mjs", import.meta.url),
+);
+const iterations = Number.parseInt(
+  process.env.REA_PROCESS_STRESS_RUNS ?? "25",
+  10,
+);
+
+if (process.platform !== "linux")
+  throw new Error("Real forkpty cleanup stress verification requires Linux");
+if (!Number.isSafeInteger(iterations) || iterations < 1 || iterations > 250)
+  throw new Error("REA_PROCESS_STRESS_RUNS must be an integer from 1 to 250");
+const capability = await probeProcessCaptureCapability();
+if (!capability.available)
+  throw new Error(`Process capture unavailable: ${capability.reason}`);
+
+for (let iteration = 1; iteration <= iterations; iteration += 1) {
+  const result = await captureProcessScenario(
+    parseProcessScenario({
+      approved: true,
+      executable: process.execPath,
+      arguments: [fixture, "tree"],
+      working_directory: dirname(fixture),
+      timeout_ms: 1_000,
+      idle_timeout_ms: 2_000,
+      settle_ms: 50,
+    }),
+    {
+      enabled: true,
+      executableRoots: [dirname(process.execPath)],
+      workingRoots: [dirname(fixture)],
+      allowedEnvironment: [],
+      allowExternalNetwork: true,
+    },
+  );
+  if (!result.ok)
+    throw new Error(`forkpty cleanup run ${String(iteration)} failed`, {
+      cause: result.error,
+    });
+  if (
+    result.value.cleanup.owned_process_group !== "verified" ||
+    result.value.cleanup.temporary_root !== "removed"
+  )
+    throw new Error(`forkpty cleanup run ${String(iteration)} was incomplete`);
+  const commands = result.value.process_samples.map(({ command }) => command);
+  if (!commands.some((command) => command.includes("tree-child")))
+    throw new Error(
+      `forkpty cleanup run ${String(iteration)} missed its child`,
+    );
+
+  const { stdout } = await execFileAsync("ps", ["-axo", "command="]);
+  if (
+    stdout.includes(`${fixture} tree-child`) ||
+    stdout.includes(`${fixture} tree-grandchild`)
+  )
+    throw new Error(
+      `forkpty cleanup run ${String(iteration)} leaked a process`,
+    );
+}
+
+process.stdout.write(
+  `${JSON.stringify({ platform: process.platform, iterations, verified: true })}\n`,
+);