diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index ba11ca658fd..e2fcfe1b0f1 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -1236,6 +1236,7 @@ jobs:
         run: >-
           pnpm exec vitest run --config config/vitest.config.ts
           config/scripts/nsis-process-check.test.mjs
+          config/scripts/idle-cpu-process-sampling.test.mjs
 
       - name: Test Windows-specific boundaries
         run: >-
diff --git a/config/scripts/idle-cpu-process-sampling.mjs b/config/scripts/idle-cpu-process-sampling.mjs
index 81f9218e5ad..883b3c566bb 100644
--- a/config/scripts/idle-cpu-process-sampling.mjs
+++ b/config/scripts/idle-cpu-process-sampling.mjs
@@ -55,9 +55,26 @@ function readUnixProcesses() {
   return parseUnixProcesses(stdout)
 }
 
+// `Win32_Process` times are 100 ns counts. Not `Number(value)`: that turns a missing
+// field into a real-looking 0, so the CPU delta would silently go kernel-only.
+function cimTimeSeconds(value) {
+  return typeof value === 'number' && Number.isFinite(value) ? value / 10_000_000 : null
+}
+
+export function cimCpuSeconds(entry) {
+  const userModeSeconds = cimTimeSeconds(entry.UserModeTime)
+  const kernelModeSeconds = cimTimeSeconds(entry.KernelModeTime)
+  return userModeSeconds !== null && kernelModeSeconds !== null
+    ? userModeSeconds + kernelModeSeconds
+    : null
+}
+
 function readWindowsProcesses() {
+  // Why UTF-8: the default OEM code page best-fits characters such as `•` or `→` in any
+  // process's command line to raw control bytes (0x07, 0x1A), which JSON.parse rejects.
   const script =
-    'Get-CimInstance Win32_Process | Select-Object ProcessId,ParentProcessId,WorkingSetSize,CommandLine | ConvertTo-Json -Compress'
+    '[Console]::OutputEncoding = [System.Text.Encoding]::UTF8; ' +
+    'Get-CimInstance Win32_Process | Select-Object ProcessId,ParentProcessId,WorkingSetSize,UserModeTime,KernelModeTime,CommandLine | ConvertTo-Json -Compress'
   const result = spawnSync('powershell.exe', ['-NoProfile', '-Command', script], {
     encoding: 'utf8',
     maxBuffer: 20 * 1024 * 1024
@@ -71,7 +88,7 @@ function readWindowsProcesses() {
     pid: Number(entry.ProcessId),
     ppid: Number(entry.ParentProcessId),
     percentCpu: 0,
-    cpuTimeSeconds: null,
+    cpuTimeSeconds: cimCpuSeconds(entry),
     rssBytes: Number(entry.WorkingSetSize) || 0,
     command: String(entry.CommandLine || '')
   }))
diff --git a/config/scripts/idle-cpu-process-sampling.test.mjs b/config/scripts/idle-cpu-process-sampling.test.mjs
index d452c6e3ce0..2c25187ea9f 100644
--- a/config/scripts/idle-cpu-process-sampling.test.mjs
+++ b/config/scripts/idle-cpu-process-sampling.test.mjs
@@ -1,5 +1,10 @@
+import { spawn } from 'node:child_process'
 import { describe, expect, it } from 'vitest'
-import { sampleProcessTreeUntilWorkloadsComplete } from './idle-cpu-process-sampling.mjs'
+import {
+  cimCpuSeconds,
+  readProcessRows,
+  sampleProcessTreeUntilWorkloadsComplete
+} from './idle-cpu-process-sampling.mjs'
 
 function createClock(workloadCompletesAt) {
   let currentMs = 0
@@ -27,6 +32,39 @@ function createClock(workloadCompletesAt) {
   return { now: () => currentMs, readRows, wait, workloadPromise }
 }
 
+describe('Windows CIM CPU time mapping', () => {
+  it('converts the 100ns user and kernel times to a summed second count', () => {
+    // 10_000_000 and 25_000_000 units of 100ns are 1s and 2.5s.
+    expect(cimCpuSeconds({ UserModeTime: 10_000_000, KernelModeTime: 25_000_000 })).toBe(3.5)
+  })
+
+  it('maps a missing or non-numeric time to null instead of a kernel-only reading', () => {
+    expect(cimCpuSeconds({ UserModeTime: null, KernelModeTime: 10_000_000 })).toBeNull()
+    expect(cimCpuSeconds({ KernelModeTime: 10_000_000 })).toBeNull()
+    expect(cimCpuSeconds({ UserModeTime: '10000000', KernelModeTime: 10_000_000 })).toBeNull()
+    expect(cimCpuSeconds({ UserModeTime: Number.NaN, KernelModeTime: 10_000_000 })).toBeNull()
+    expect(
+      cimCpuSeconds({ UserModeTime: Number.POSITIVE_INFINITY, KernelModeTime: 10_000_000 })
+    ).toBeNull()
+  })
+})
+
+describe.skipIf(process.platform !== 'win32')('Windows process table read', () => {
+  it('parses a command line whose characters the OEM code page maps to control bytes', () => {
+    const marker = 'idle-cpu-oem • → ♪'
+    const child = spawn(process.execPath, ['-e', 'setTimeout(() => {}, 30_000)', marker], {
+      stdio: 'ignore'
+    })
+    try {
+      const row = readProcessRows().find((candidate) => candidate.pid === child.pid)
+      expect(row?.command).toContain(marker)
+      expect(row?.cpuTimeSeconds).toEqual(expect.any(Number))
+    } finally {
+      child.kill()
+    }
+  }, 30_000)
+})
+
 describe('idle CPU process sampling window', () => {
   it('extends through a slow workload and captures a final CPU delta', async () => {
     const clock = createClock(40)
diff --git a/config/scripts/pr-code-change-scope.mjs b/config/scripts/pr-code-change-scope.mjs
index 149c49a2d11..e04946456e4 100644
--- a/config/scripts/pr-code-change-scope.mjs
+++ b/config/scripts/pr-code-change-scope.mjs
@@ -372,6 +372,7 @@ const WINDOWS_PACKAGE_TESTS = [
   'config/scripts/rebuild-native-deps-windows-process-tree.test.mjs',
   'config/scripts/rebuild-native-deps-node-pty.test.mjs',
   'config/scripts/nsis-process-check.test.mjs',
+  'config/scripts/idle-cpu-process-sampling.test.mjs',
   'config/scripts/ensure-native-runtime-job-ownership.test.mjs',
   'config/scripts/verify-packaged-node-pty-job-ownership.test.mjs',
   'config/scripts/windows-pe-machine.test.mjs',
diff --git a/config/scripts/run-idle-cpu-benchmark.mjs b/config/scripts/run-idle-cpu-benchmark.mjs
index 3892de8845d..eb3ebd3ea31 100644
--- a/config/scripts/run-idle-cpu-benchmark.mjs
+++ b/config/scripts/run-idle-cpu-benchmark.mjs
@@ -159,11 +159,17 @@ function buildAppIfNeeded(root, skipBuild) {
     throw new Error(`--skip-build requested, but ${mainPath} does not exist`)
   }
   console.log('[idle-cpu] building Electron app with electron-vite --mode e2e')
-  run('npx', ['electron-vite', 'build', '--mode', 'e2e'], {
-    cwd: root,
-    stdio: 'inherit',
-    env: { ...process.env, VITE_EXPOSE_STORE: 'true' }
-  })
+  // Why through the wrapper: `npx` only resolves to an executable on POSIX; on Windows it is
+  // `npx.cmd`, which execFileSync cannot run, and the wrapper also verifies the boot graph.
+  run(
+    process.execPath,
+    [path.join(root, 'config', 'scripts', 'run-electron-vite-build.mjs'), '--mode', 'e2e'],
+    {
+      cwd: root,
+      stdio: 'inherit',
+      env: { ...process.env, VITE_EXPOSE_STORE: 'true' }
+    }
+  )
   return mainPath
 }
 
@@ -348,7 +354,7 @@ async function main() {
         return { error: added.error }
       }
       const store = window.__store
-      await store?.getState().fetchRepos()
+      await store?.getState().fetchRepos({ runtimeEnvironmentId: null })
       const repo = store?.getState().repos.find((candidate) => candidate.id === added.repo.id)
       if (repo) {
         const detected = await store