From 4231c3c0ff09747e10b17ffec77ab22f50bbbdea Mon Sep 17 00:00:00 2001
From: Neil <4138956+nwparker@users.noreply.github.com>
Date: Wed, 29 Jul 2026 20:12:15 -0700
Subject: [PATCH] perf(main): add watchdog boundary memory benchmark

Add a repeatable Electron 43 RSS harness that measures the production-built watchdog entry across the child-process and worker-thread boundaries. Record per-trial samples, the median, revision, runtime, and settling procedure for reproducible PR evidence.
---
 .../hang-watchdog-memory-benchmark.mjs        | 443 ++++++++++++++++++
 .../scripts/hang-watchdog-process-metrics.mjs | 108 +++++
 .../hang-watchdog-process-metrics.test.mjs    |  45 ++
 package.json                                  |   1 +
 4 files changed, 597 insertions(+)
 create mode 100644 config/scripts/hang-watchdog-memory-benchmark.mjs
 create mode 100644 config/scripts/hang-watchdog-process-metrics.mjs
 create mode 100644 config/scripts/hang-watchdog-process-metrics.test.mjs

diff --git a/config/scripts/hang-watchdog-memory-benchmark.mjs b/config/scripts/hang-watchdog-memory-benchmark.mjs
new file mode 100644
index 00000000000..49a2dd63136
--- /dev/null
+++ b/config/scripts/hang-watchdog-memory-benchmark.mjs
@@ -0,0 +1,443 @@
+#!/usr/bin/env node
+import { execFileSync, fork, spawnSync } from 'node:child_process'
+import { existsSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import path from 'node:path'
+import { fileURLToPath, pathToFileURL } from 'node:url'
+import { Worker } from 'node:worker_threads'
+import {
+  childRssBytes,
+  median,
+  physicalFootprintBytes,
+  sampleMemory,
+  sampleProductionPerformance
+} from './hang-watchdog-process-metrics.mjs'
+
+const INTERNAL_ENV = 'ORCA_HANG_WATCHDOG_BENCH_INTERNAL'
+const BOUNDARY_ENV = 'ORCA_HANG_WATCHDOG_BENCH_BOUNDARY'
+const RESULT_PREFIX = 'ORCA_HANG_WATCHDOG_BENCH_RESULT='
+const DEFAULT_TRIALS = 7
+const SETTLE_MS = 2_000
+const SAMPLE_COUNT = 5
+const SAMPLE_INTERVAL_MS = 200
+const VERIFY_TIMEOUT_MS = 500
+const VERIFY_CHECK_INTERVAL_MS = 50
+const VERIFY_BLOCK_MS = 1_200
+const PRODUCTION_HEARTBEAT_INTERVAL_MS = 2_000
+const PRODUCTION_TIMEOUT_MS = 45_000
+const PRODUCTION_CHECK_INTERVAL_MS = 5_000
+const PRODUCTION_SAMPLE_MS = 30_000
+const MAX_LAUNCH_ATTEMPTS = 3
+const MIB = 1024 * 1024
+const scriptPath = import.meta.filename
+const repoRoot = path.resolve(import.meta.dirname, '..', '..')
+const entryPath = path.join(repoRoot, 'out', 'main', 'main-thread-hang-watchdog-entry.js')
+
+function sleep(ms) {
+  return new Promise((resolve) => setTimeout(resolve, ms))
+}
+
+function forceGc() {
+  if (typeof global.gc !== 'function') {
+    throw new Error('Electron did not expose GC; keep --js-flags=--expose-gc in the harness')
+  }
+  global.gc()
+  global.gc()
+}
+
+function blockMainThread(ms) {
+  const startedAt = Date.now()
+  while (Date.now() - startedAt < ms) {
+    // Intentional synchronous stall.
+  }
+  return { startedAt, endedAt: Date.now() }
+}
+
+function readMarker(markerPath) {
+  try {
+    return JSON.parse(readFileSync(markerPath, 'utf8'))
+  } catch {
+    return null
+  }
+}
+
+async function verifyBlockedMainDetection(markerPath, sendHeartbeat) {
+  const block = blockMainThread(VERIFY_BLOCK_MS)
+  const detected = readMarker(markerPath)
+  sendHeartbeat()
+  const deadline = Date.now() + VERIFY_TIMEOUT_MS
+  let resolved
+  do {
+    resolved = readMarker(markerPath)
+    if (resolved?.selfRecovered === true) {
+      break
+    }
+    await sleep(VERIFY_CHECK_INTERVAL_MS)
+  } while (Date.now() < deadline)
+  const verified =
+    detected?.detectedAt >= block.startedAt &&
+    detected.detectedAt <= block.endedAt &&
+    detected.selfRecovered === false &&
+    resolved?.selfRecovered === true
+  if (!verified) {
+    throw new Error(
+      `Built watchdog failed blocked-main verification: ${JSON.stringify({ detected, resolved })}`
+    )
+  }
+  return true
+}
+
+function startChild(markerPath, timeoutMs, checkIntervalMs) {
+  const startedAt = process.hrtime.bigint()
+  const child = fork(entryPath, [], {
+    stdio: ['ignore', 'ignore', 'ignore', 'ipc'],
+    env: {
+      ...process.env,
+      ELECTRON_RUN_AS_NODE: '1',
+      ORCA_HANG_WATCHDOG_PARENT_PID: String(process.pid),
+      ORCA_HANG_WATCHDOG_MARKER_PATH: markerPath,
+      ORCA_HANG_WATCHDOG_TIMEOUT_MS: String(timeoutMs),
+      ORCA_HANG_WATCHDOG_CHECK_INTERVAL_MS: String(checkIntervalMs)
+    }
+  })
+  const startupMs = Number(process.hrtime.bigint() - startedAt) / 1e6
+  return {
+    pids: [process.pid, child.pid],
+    startupMs,
+    sendHeartbeat: () => child.send?.({ type: 'heartbeat' }),
+    shutdown: async () => {
+      if (child.exitCode !== null) {
+        return
+      }
+      const exitPromise = new Promise((resolve) => child.once('exit', resolve))
+      child.send?.({ type: 'shutdown' })
+      if (child.connected) {
+        child.disconnect()
+      }
+      await exitPromise
+    }
+  }
+}
+
+function startWorker(markerPath, timeoutMs, checkIntervalMs) {
+  const startedAt = process.hrtime.bigint()
+  const worker = new Worker(entryPath, {
+    workerData: {
+      parentPid: process.pid,
+      markerPath,
+      timeoutMs,
+      checkIntervalMs
+    }
+  })
+  const startupMs = Number(process.hrtime.bigint() - startedAt) / 1e6
+  return {
+    pids: [process.pid],
+    startupMs,
+    sendHeartbeat: () => worker.postMessage({ type: 'heartbeat' }),
+    shutdown: async () => {
+      if (worker.threadId === -1) {
+        return
+      }
+      const exitPromise = new Promise((resolve) => worker.once('exit', resolve))
+      worker.postMessage({ type: 'shutdown' })
+      await exitPromise
+    }
+  }
+}
+
+async function verifyBoundary(markerPath, startBoundary) {
+  const boundary = startBoundary(markerPath, VERIFY_TIMEOUT_MS, VERIFY_CHECK_INTERVAL_MS)
+  const heartbeat = setInterval(boundary.sendHeartbeat, 100)
+  try {
+    await sleep(SETTLE_MS)
+    return await verifyBlockedMainDetection(markerPath, boundary.sendHeartbeat)
+  } finally {
+    clearInterval(heartbeat)
+    await boundary.shutdown()
+  }
+}
+
+async function measureChild(markerPath) {
+  forceGc()
+  await sleep(SETTLE_MS)
+  forceGc()
+  const before = await sampleMemory(
+    () => process.memoryUsage().rss,
+    () => physicalFootprintBytes([process.pid]),
+    { sampleCount: SAMPLE_COUNT, sampleIntervalMs: SAMPLE_INTERVAL_MS, sleep }
+  )
+  const child = startChild(markerPath, PRODUCTION_TIMEOUT_MS, PRODUCTION_CHECK_INTERVAL_MS)
+  let measurements
+  try {
+    await sleep(SETTLE_MS)
+    forceGc()
+    const childRss = await sampleMemory(
+      () => childRssBytes(child.pids[1]),
+      () => physicalFootprintBytes([child.pids[1]]),
+      { sampleCount: SAMPLE_COUNT, sampleIntervalMs: SAMPLE_INTERVAL_MS, sleep }
+    )
+    const total = await sampleMemory(
+      () => process.memoryUsage().rss + childRssBytes(child.pids[1]),
+      () => physicalFootprintBytes(child.pids),
+      { sampleCount: SAMPLE_COUNT, sampleIntervalMs: SAMPLE_INTERVAL_MS, sleep }
+    )
+    const performance = await sampleProductionPerformance(child, {
+      heartbeatIntervalMs: PRODUCTION_HEARTBEAT_INTERVAL_MS,
+      sampleMs: PRODUCTION_SAMPLE_MS,
+      sleep
+    })
+    measurements = {
+      rssBytes: childRss.rssBytes,
+      summedProcessRssDeltaBytes: Math.max(0, total.rssBytes - before.rssBytes),
+      physicalFootprintDeltaBytes: Math.max(
+        0,
+        total.physicalFootprintBytes - before.physicalFootprintBytes
+      ),
+      startupMs: child.startupMs,
+      ...performance
+    }
+  } finally {
+    await child.shutdown()
+  }
+  rmSync(markerPath, { force: true })
+  return {
+    ...measurements,
+    blockedMainThreadVerified: await verifyBoundary(markerPath, startChild)
+  }
+}
+
+async function measureWorker(markerPath) {
+  forceGc()
+  await sleep(SETTLE_MS)
+  forceGc()
+  const before = await sampleMemory(
+    () => process.memoryUsage().rss,
+    () => physicalFootprintBytes([process.pid]),
+    { sampleCount: SAMPLE_COUNT, sampleIntervalMs: SAMPLE_INTERVAL_MS, sleep }
+  )
+  const worker = startWorker(markerPath, PRODUCTION_TIMEOUT_MS, PRODUCTION_CHECK_INTERVAL_MS)
+  let measurements
+  try {
+    await sleep(SETTLE_MS)
+    forceGc()
+    const after = await sampleMemory(
+      () => process.memoryUsage().rss,
+      () => physicalFootprintBytes([process.pid]),
+      { sampleCount: SAMPLE_COUNT, sampleIntervalMs: SAMPLE_INTERVAL_MS, sleep }
+    )
+    const performance = await sampleProductionPerformance(worker, {
+      heartbeatIntervalMs: PRODUCTION_HEARTBEAT_INTERVAL_MS,
+      sampleMs: PRODUCTION_SAMPLE_MS,
+      sleep
+    })
+    const rssBytes = Math.max(0, after.rssBytes - before.rssBytes)
+    measurements = {
+      rssBytes,
+      summedProcessRssDeltaBytes: rssBytes,
+      physicalFootprintDeltaBytes: Math.max(
+        0,
+        after.physicalFootprintBytes - before.physicalFootprintBytes
+      ),
+      startupMs: worker.startupMs,
+      ...performance
+    }
+  } finally {
+    await worker.shutdown()
+  }
+  rmSync(markerPath, { force: true })
+  return {
+    ...measurements,
+    blockedMainThreadVerified: await verifyBoundary(markerPath, startWorker)
+  }
+}
+
+async function runInternal() {
+  if (process.platform !== 'darwin') {
+    throw new Error('The production watchdog is macOS-only; run this benchmark on macOS')
+  }
+  const { app } = await import('electron')
+  const boundary = process.env[BOUNDARY_ENV]
+  const profileDir = mkdtempSync(path.join(tmpdir(), 'orca-watchdog-bench-'))
+  app.setPath('userData', profileDir)
+  try {
+    await app.whenReady()
+    const markerPath = path.join(profileDir, 'main-thread-hang.json')
+    const result =
+      boundary === 'child'
+        ? await measureChild(markerPath)
+        : boundary === 'worker'
+          ? await measureWorker(markerPath)
+          : (() => {
+              throw new Error(`Unsupported boundary: ${boundary}`)
+            })()
+    process.stdout.write(`${RESULT_PREFIX}${JSON.stringify(result)}\n`)
+  } finally {
+    app.quit()
+    rmSync(profileDir, { recursive: true, force: true })
+  }
+}
+
+function parseArgs(argv) {
+  const options = { boundary: '', trials: DEFAULT_TRIALS, output: '' }
+  for (let index = 0; index < argv.length; index += 1) {
+    const arg = argv[index]
+    const value = argv[index + 1]
+    if (arg === '--boundary' || arg === '--trials' || arg === '--output') {
+      if (!value) {
+        throw new Error(`Missing value for ${arg}`)
+      }
+      options[arg.slice(2)] = arg === '--trials' ? Number(value) : value
+      index += 1
+    } else {
+      throw new Error(`Unknown argument: ${arg}`)
+    }
+  }
+  if (!['child', 'worker'].includes(options.boundary)) {
+    throw new Error('--boundary must be child or worker')
+  }
+  if (!Number.isInteger(options.trials) || options.trials < 1) {
+    throw new Error('--trials must be a positive integer')
+  }
+  return options
+}
+
+function electronPath() {
+  const requirePath = import.meta.resolve('electron')
+  const electronModulePath = fileURLToPath(requirePath)
+  return execFileSync(
+    process.execPath,
+    ['-e', `process.stdout.write(require(${JSON.stringify(electronModulePath)}))`],
+    {
+      encoding: 'utf8'
+    }
+  )
+}
+
+function runTrial(executable, boundary) {
+  for (let attempt = 1; attempt <= MAX_LAUNCH_ATTEMPTS; attempt += 1) {
+    const env = { ...process.env, [INTERNAL_ENV]: '1', [BOUNDARY_ENV]: boundary }
+    delete env.ELECTRON_RUN_AS_NODE
+    const launcherDir = mkdtempSync(path.join(tmpdir(), 'orca-watchdog-bench-launcher-'))
+    writeFileSync(
+      path.join(launcherDir, 'package.json'),
+      JSON.stringify({ name: 'orca-watchdog-benchmark', main: 'main.cjs' })
+    )
+    writeFileSync(
+      path.join(launcherDir, 'main.cjs'),
+      `import(${JSON.stringify(pathToFileURL(scriptPath).href)}).catch((error) => {
+  console.error(error)
+  process.exitCode = 1
+})\n`
+    )
+    let result
+    try {
+      result = spawnSync(executable, ['--js-flags=--expose-gc', launcherDir], {
+        cwd: repoRoot,
+        env,
+        encoding: 'utf8',
+        timeout: 90_000
+      })
+    } finally {
+      rmSync(launcherDir, { recursive: true, force: true })
+    }
+    if (result.status !== 0) {
+      throw new Error(
+        `Electron trial failed (${result.error?.message ?? result.signal ?? result.status}):\n` +
+          `${result.stderr || result.stdout}`
+      )
+    }
+    const line = result.stdout.split('\n').find((candidate) => candidate.startsWith(RESULT_PREFIX))
+    if (line) {
+      return { ...JSON.parse(line.slice(RESULT_PREFIX.length)), launchAttempts: attempt }
+    }
+    if (attempt === MAX_LAUNCH_ATTEMPTS || result.stderr || result.stdout) {
+      throw new Error(`Electron trial did not report a result (status ${result.status})`)
+    }
+  }
+  throw new Error('Electron trial exhausted launcher attempts')
+}
+
+function runBenchmark() {
+  if (process.platform !== 'darwin') {
+    throw new Error('The production watchdog is macOS-only; run this benchmark on macOS')
+  }
+  if (!existsSync(entryPath)) {
+    throw new Error(`Missing ${entryPath}; run pnpm exec electron-vite build first`)
+  }
+  const options = parseArgs(process.argv.slice(2))
+  const builtEntry = readFileSync(entryPath, 'utf8')
+  const hasChildContract = builtEntry.includes('ORCA_HANG_WATCHDOG_PARENT_PID')
+  const hasWorkerContract = builtEntry.includes('workerData') && builtEntry.includes('parentPort')
+  if (
+    (options.boundary === 'child' && !hasChildContract) ||
+    (options.boundary === 'worker' && !hasWorkerContract)
+  ) {
+    throw new Error(
+      `Built watchdog does not implement the requested ${options.boundary} boundary; rebuild the matching revision`
+    )
+  }
+  const executable = electronPath()
+  const results = Array.from({ length: options.trials }, () =>
+    runTrial(executable, options.boundary)
+  )
+  const rssBytes = results.map((result) => result.rssBytes)
+  const summedProcessRssDeltaBytes = results.map((result) => result.summedProcessRssDeltaBytes)
+  const physicalFootprintDeltaBytes = results.map((result) => result.physicalFootprintDeltaBytes)
+  const startupMs = results.map((result) => result.startupMs)
+  const cpuMs = results.map((result) => result.cpuMs)
+  const eventLoopDelayP95Ms = results.map((result) => result.eventLoopDelayP95Ms)
+  const eventLoopDelayP99Ms = results.map((result) => result.eventLoopDelayP99Ms)
+  const eventLoopDelayMaxMs = results.map((result) => result.eventLoopDelayMaxMs)
+  const report = {
+    benchmark: 'hang-watchdog-memory',
+    boundary: options.boundary,
+    revision: execFileSync('git', ['rev-parse', 'HEAD'], {
+      cwd: repoRoot,
+      encoding: 'utf8'
+    }).trim(),
+    electron: execFileSync(executable, ['-e', 'process.stdout.write(process.versions.electron)'], {
+      env: { ...process.env, ELECTRON_RUN_AS_NODE: '1' },
+      encoding: 'utf8'
+    }).trim(),
+    settleMs: SETTLE_MS,
+    samplesPerTrial: SAMPLE_COUNT,
+    productionHeartbeatIntervalMs: PRODUCTION_HEARTBEAT_INTERVAL_MS,
+    productionCheckIntervalMs: PRODUCTION_CHECK_INTERVAL_MS,
+    productionSampleMs: PRODUCTION_SAMPLE_MS,
+    trials: options.trials,
+    rssMiB: rssBytes.map((value) => Number((value / MIB).toFixed(2))),
+    medianRssMiB: Number((median(rssBytes) / MIB).toFixed(2)),
+    summedProcessRssDeltaMiB: summedProcessRssDeltaBytes.map((value) =>
+      Number((value / MIB).toFixed(2))
+    ),
+    medianSummedProcessRssDeltaMiB: Number((median(summedProcessRssDeltaBytes) / MIB).toFixed(2)),
+    physicalFootprintDeltaMiB: physicalFootprintDeltaBytes.map((value) =>
+      Number((value / MIB).toFixed(2))
+    ),
+    medianPhysicalFootprintDeltaMiB: Number((median(physicalFootprintDeltaBytes) / MIB).toFixed(2)),
+    startupMs: startupMs.map((value) => Number(value.toFixed(3))),
+    medianStartupMs: Number(median(startupMs).toFixed(3)),
+    cpuMs: cpuMs.map((value) => Number(value.toFixed(2))),
+    medianCpuMs: Number(median(cpuMs).toFixed(2)),
+    eventLoopDelayP95Ms: eventLoopDelayP95Ms.map((value) => Number(value.toFixed(3))),
+    medianEventLoopDelayP95Ms: Number(median(eventLoopDelayP95Ms).toFixed(3)),
+    eventLoopDelayP99Ms: eventLoopDelayP99Ms.map((value) => Number(value.toFixed(3))),
+    medianEventLoopDelayP99Ms: Number(median(eventLoopDelayP99Ms).toFixed(3)),
+    eventLoopDelayMaxMs: eventLoopDelayMaxMs.map((value) => Number(value.toFixed(3))),
+    medianEventLoopDelayMaxMs: Number(median(eventLoopDelayMaxMs).toFixed(3)),
+    heartbeatCounts: results.map((result) => result.heartbeatCount),
+    launchAttempts: results.map((result) => result.launchAttempts),
+    blockedMainThreadVerified: results.every((result) => result.blockedMainThreadVerified)
+  }
+  const serialized = `${JSON.stringify(report, null, 2)}\n`
+  process.stdout.write(serialized)
+  if (options.output) {
+    writeFileSync(path.resolve(options.output), serialized)
+  }
+}
+
+if (process.env[INTERNAL_ENV] === '1') {
+  await runInternal()
+} else {
+  runBenchmark()
+}
diff --git a/config/scripts/hang-watchdog-process-metrics.mjs b/config/scripts/hang-watchdog-process-metrics.mjs
new file mode 100644
index 00000000000..7e5ee4de53f
--- /dev/null
+++ b/config/scripts/hang-watchdog-process-metrics.mjs
@@ -0,0 +1,108 @@
+import { execFileSync } from 'node:child_process'
+import { monitorEventLoopDelay } from 'node:perf_hooks'
+
+export function median(values) {
+  const sorted = [...values].sort((left, right) => left - right)
+  const middle = Math.floor(sorted.length / 2)
+  return sorted.length % 2 === 0 ? (sorted[middle - 1] + sorted[middle]) / 2 : sorted[middle]
+}
+
+export async function sampleMemory(readRss, readPhysicalFootprint, options) {
+  const rssSamples = []
+  const physicalFootprintSamples = []
+  for (let index = 0; index < options.sampleCount; index += 1) {
+    rssSamples.push(readRss())
+    physicalFootprintSamples.push(readPhysicalFootprint())
+    await options.sleep(options.sampleIntervalMs)
+  }
+  return {
+    rssBytes: median(rssSamples),
+    physicalFootprintBytes: median(physicalFootprintSamples)
+  }
+}
+
+export function childRssBytes(pid) {
+  const raw = execFileSync('ps', ['-o', 'rss=', '-p', String(pid)], {
+    encoding: 'utf8'
+  }).trim()
+  const rssKiB = Number(raw)
+  if (!Number.isFinite(rssKiB) || rssKiB <= 0) {
+    throw new Error(`Could not read watchdog child RSS for PID ${pid}`)
+  }
+  return rssKiB * 1024
+}
+
+export function parsePhysicalFootprintBytes(output, processCount) {
+  const match =
+    processCount > 1
+      ? output.match(/^Summary Footprint:\s+(\d+) B$/m)
+      : output.match(/^[^\s].*\sFootprint:\s+(\d+) B/m)
+  const bytes = Number(match?.[1])
+  return Number.isFinite(bytes) && bytes > 0 ? bytes : null
+}
+
+export function physicalFootprintBytes(pids) {
+  const pidArgs = pids.flatMap((pid) => ['--pid', String(pid)])
+  const output = execFileSync(
+    '/usr/bin/footprint',
+    [...pidArgs, '--format', 'bytes', '--noCategories'],
+    { encoding: 'utf8' }
+  )
+  const bytes = parsePhysicalFootprintBytes(output, pids.length)
+  if (bytes === null) {
+    throw new Error(`Could not read physical footprint for PIDs ${pids.join(', ')}`)
+  }
+  return bytes
+}
+
+export function parseProcessCpuTimeMs(raw) {
+  if (!raw.trim()) {
+    return null
+  }
+  const parts = raw.split(':').map(Number)
+  if (!parts.length || parts.some((part) => !Number.isFinite(part))) {
+    return null
+  }
+  const seconds = parts.reduce((total, part) => total * 60 + part, 0)
+  const milliseconds = seconds * 1_000
+  return milliseconds >= 0 ? milliseconds : null
+}
+
+function processCpuTimeMs(pid) {
+  const raw = execFileSync('ps', ['-o', 'time=', '-p', String(pid)], {
+    encoding: 'utf8'
+  }).trim()
+  const milliseconds = parseProcessCpuTimeMs(raw)
+  if (milliseconds === null) {
+    throw new Error(`Could not read CPU time for PID ${pid}`)
+  }
+  return milliseconds
+}
+
+function combinedCpuTimeMs(pids) {
+  return pids.reduce((total, pid) => total + processCpuTimeMs(pid), 0)
+}
+
+export async function sampleProductionPerformance(boundary, options) {
+  const loopDelay = monitorEventLoopDelay({ resolution: 10 })
+  let heartbeatCount = 0
+  const heartbeat = setInterval(() => {
+    heartbeatCount += 1
+    boundary.sendHeartbeat()
+  }, options.heartbeatIntervalMs)
+  const cpuBefore = combinedCpuTimeMs(boundary.pids)
+  loopDelay.enable()
+  try {
+    await options.sleep(options.sampleMs)
+  } finally {
+    loopDelay.disable()
+    clearInterval(heartbeat)
+  }
+  return {
+    cpuMs: Math.max(0, combinedCpuTimeMs(boundary.pids) - cpuBefore),
+    heartbeatCount,
+    eventLoopDelayP95Ms: loopDelay.percentile(95) / 1e6,
+    eventLoopDelayP99Ms: loopDelay.percentile(99) / 1e6,
+    eventLoopDelayMaxMs: loopDelay.max / 1e6
+  }
+}
diff --git a/config/scripts/hang-watchdog-process-metrics.test.mjs b/config/scripts/hang-watchdog-process-metrics.test.mjs
new file mode 100644
index 00000000000..2d54e691d00
--- /dev/null
+++ b/config/scripts/hang-watchdog-process-metrics.test.mjs
@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest'
+import {
+  parsePhysicalFootprintBytes,
+  parseProcessCpuTimeMs
+} from './hang-watchdog-process-metrics.mjs'
+
+describe('hang watchdog process metrics', () => {
+  it('uses the de-duplicated summary for multiple processes', () => {
+    const output = `
+Electron [101]: 64-bit    Footprint: 5000000 B (16384 bytes per page)
+    phys_footprint: 5100000 B
+Electron Helper [102]: 64-bit    Footprint: 2000000 B (16384 bytes per page)
+    phys_footprint: 2100000 B
+Summary Footprint: 6259264 B
+`
+    expect(parsePhysicalFootprintBytes(output, 2)).toBe(6_259_264)
+  })
+
+  it('uses the process footprint rather than auxiliary accounting for one process', () => {
+    const output = `
+Electron [101]: 64-bit    Footprint: 5000000 B (16384 bytes per page)
+    phys_footprint: 5100000 B
+`
+    expect(parsePhysicalFootprintBytes(output, 1)).toBe(5_000_000)
+  })
+
+  it('rejects missing or zero footprint summaries', () => {
+    expect(parsePhysicalFootprintBytes('phys_footprint: 100 B', 2)).toBeNull()
+    expect(parsePhysicalFootprintBytes('Summary Footprint: 0 B', 2)).toBeNull()
+  })
+
+  it.each([
+    ['0:00.04', 40],
+    ['1:02.50', 62_500],
+    ['2:01:02.50', 7_262_500]
+  ])('parses ps CPU time %s', (value, expected) => {
+    expect(parseProcessCpuTimeMs(value)).toBe(expected)
+  })
+
+  it('rejects invalid CPU times', () => {
+    expect(parseProcessCpuTimeMs('')).toBeNull()
+    expect(parseProcessCpuTimeMs('not-a-time')).toBeNull()
+    expect(parseProcessCpuTimeMs('-1:00')).toBeNull()
+  })
+})
diff --git a/package.json b/package.json
index fe23f109180..8b124f8ae44 100644
--- a/package.json
+++ b/package.json
@@ -105,6 +105,7 @@
     "bench:idle-cpu": "pnpm run ensure:electron-runtime && node config/scripts/run-idle-cpu-benchmark.mjs",
     "bench:startup": "pnpm run ensure:electron-runtime && node tools/benchmarks/startup-time-bench.mjs",
     "bench:daemon-coldstart": "pnpm run ensure:electron-runtime && node tools/benchmarks/daemon-coldstart-bench.mjs",
+    "bench:hang-watchdog-memory": "pnpm run ensure:electron-runtime && node config/scripts/hang-watchdog-memory-benchmark.mjs",
     "bench:main-thread-jank": "pnpm run ensure:electron-runtime && node tools/benchmarks/main-thread-jank-bench.mjs",
     "bench:worktree-deletion": "node tools/benchmarks/worktree-deletion-dev-bench.mjs",
     "bench:zustand-selector-fanout": "node config/scripts/zustand-selector-fanout-benchmark.mjs",