diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index 13a2b90ec12..1136927d201 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -52,6 +52,7 @@ jobs:
       cross-version-wire: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.cross-version-wire }}
       managed_hook_node18: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.managed_hook_node18 }}
       package: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.package }}
+      windows_process_probe: ${{ steps.filter.outputs.windows_process_probe }}
       package_windows: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.package_windows }}
       layout_oracle: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.layout_oracle }}
       dependency_isolation: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.dependency_isolation }}
@@ -1341,6 +1342,9 @@ jobs:
       # vitest runs here directly rather than through `pnpm test`, so the addon
       # assertions only hold once install-node-dependencies has rebuilt natives.
       - name: Test Windows installer process probe
+        if: needs.code_paths.outputs.windows_process_probe != 'false'
+        env:
+          ORCA_BACKGROUND_LAUNCH: '1'
         # Serialize the two suites so their cold PowerShell/CIM starts cannot contend.
         run: >-
           pnpm exec vitest run --config config/vitest.config.ts
diff --git a/config/scripts/pr-code-change-scope-windows-process-probe.test.mjs b/config/scripts/pr-code-change-scope-windows-process-probe.test.mjs
new file mode 100644
index 00000000000..2ee86621d31
--- /dev/null
+++ b/config/scripts/pr-code-change-scope-windows-process-probe.test.mjs
@@ -0,0 +1,53 @@
+import { readFileSync } from 'node:fs'
+import { describe, expect, it } from 'vitest'
+import { parse } from 'yaml'
+import { classifyPrJobs } from './pr-code-change-scope.mjs'
+
+const prWorkflow = parse(
+  readFileSync(new URL('../../.github/workflows/pr.yml', import.meta.url), 'utf8')
+)
+
+describe('Windows installer process probe routing', () => {
+  it.each([
+    [],
+    ['config/nsis/orca-process-check.nsh'],
+    ['config/nsis/orca-installer-hooks.nsh'],
+    ['config/scripts/nsis-process-check.test.mjs'],
+    ['config/scripts/idle-cpu-process-sampling.mjs'],
+    ['config/scripts/idle-cpu-process-sampling.test.mjs'],
+    ['src/packages/process-host/src/run-process.ts'],
+    ['config/vitest.config.ts'],
+    ['config/scripts/vitest-host-ports-setup.ts'],
+    ['config/scripts/ci-unit-files.mjs'],
+    ['.github/actions/install-node-dependencies/action.yml'],
+    ['.github/workflows/pr.yml'],
+    ['package.json'],
+    ['pnpm-lock.yaml'],
+    ['src/renderer/src/App.tsx', 'config/nsis/orca-process-check.nsh']
+  ])('runs real Windows probes and their containing job for %j', (...files) => {
+    expect(classifyPrJobs(files)).toMatchObject({
+      windows_process_probe: true,
+      package_windows: true
+    })
+  })
+
+  it('keeps packaging and full unit tests for unrelated application changes', () => {
+    expect(classifyPrJobs(['src/renderer/src/App.tsx'])).toMatchObject({
+      windows_process_probe: false,
+      package_windows: true,
+      test: true
+    })
+    expect(classifyPrJobs(['docs/README.md']).windows_process_probe).toBe(false)
+  })
+
+  it('connects the router output to a fail-closed probe step', () => {
+    expect(prWorkflow.jobs.code_paths.outputs.windows_process_probe).toBe(
+      '${{ steps.filter.outputs.windows_process_probe }}'
+    )
+    const step = prWorkflow.jobs.package_windows.steps.find(
+      (candidate) => candidate.name === 'Test Windows installer process probe'
+    )
+    expect(step.if).toBe("needs.code_paths.outputs.windows_process_probe != 'false'")
+    expect(step.env.ORCA_BACKGROUND_LAUNCH).toBe('1')
+  })
+})
diff --git a/config/scripts/pr-code-change-scope.mjs b/config/scripts/pr-code-change-scope.mjs
index f9840d5de37..a456f8a4688 100644
--- a/config/scripts/pr-code-change-scope.mjs
+++ b/config/scripts/pr-code-change-scope.mjs
@@ -1,9 +1,12 @@
 import { readFileSync } from 'node:fs'
 import { join } from 'node:path'
-import process from 'node:process'
 import { pathToFileURL } from 'node:url'
 import { isLayoutOracleSource } from './pr-layout-oracle-route.mjs'
-import { LINUX_PACKAGE_TESTS, WINDOWS_PACKAGE_TESTS } from './pr-package-test-paths.mjs'
+import {
+  isWindowsProcessProbePath,
+  LINUX_PACKAGE_TESTS,
+  WINDOWS_PACKAGE_TESTS
+} from './pr-package-test-paths.mjs'
 
 const DOCS_ONLY_FILES = new Set([
   'README.md',
@@ -476,13 +479,11 @@ function readFormatIgnoredPrefixes() {
 const FORMAT_IGNORED_PREFIXES = readFormatIgnoredPrefixes()
 
 export function isDocsOnlyPath(file) {
-  if (DOCS_ONLY_FILES.has(file)) {
-    return true
-  }
-  if (DOCS_ONLY_PREFIXES.some((prefix) => file.startsWith(prefix))) {
-    return true
-  }
-  return /^README\.[^/]+\.md$/.test(file)
+  return (
+    DOCS_ONLY_FILES.has(file) ||
+    DOCS_ONLY_PREFIXES.some((prefix) => file.startsWith(prefix)) ||
+    /^README\.[^/]+\.md$/.test(file)
+  )
 }
 
 export function shouldRunPrChecks(changedFiles) {
@@ -562,6 +563,7 @@ export function classifyPrJobs(
   return {
     should_run: shouldRun,
     mobile_ci_tools: mobileCiTools,
+    windows_process_probe: shouldRun && (forceAll || changedFiles.some(isWindowsProcessProbePath)),
     // Relay contracts exercise host/cloud code; any input outside the renderer keeps them.
     relay_integration:
       shouldRun &&
@@ -617,7 +619,11 @@ function isLinuxPackagePath(file) {
 }
 
 function isWindowsPackagePath(file) {
-  return WINDOWS_PACKAGE_TESTS.includes(file) || isProductBundlePath(file, WINDOWS_PACKAGE_PREFIXES)
+  return (
+    WINDOWS_PACKAGE_TESTS.includes(file) ||
+    isWindowsProcessProbePath(file) ||
+    isProductBundlePath(file, WINDOWS_PACKAGE_PREFIXES)
+  )
 }
 
 function isProductBundlePath(file, extraPrefixes) {
diff --git a/config/scripts/pr-package-test-paths.mjs b/config/scripts/pr-package-test-paths.mjs
index bf745618567..6d79edf5850 100644
--- a/config/scripts/pr-package-test-paths.mjs
+++ b/config/scripts/pr-package-test-paths.mjs
@@ -99,6 +99,22 @@ export const WINDOWS_BOUNDARY_TESTS = [
   'src/main/skills/bundled-skill-install/plan-selection.test.ts'
 ]
 
+const WINDOWS_PROCESS_PROBE_PREFIXES = [
+  'config/nsis/',
+  'config/scripts/nsis-process-check',
+  'config/scripts/idle-cpu-process-sampling',
+  'config/vitest.config.',
+  'config/scripts/vitest-',
+  'config/scripts/ci-unit-',
+  'config/scripts/workspace-source-exports',
+  'config/dark-build-switches.',
+  'src/packages/process-host/'
+]
+
+export function isWindowsProcessProbePath(file) {
+  return WINDOWS_PROCESS_PROBE_PREFIXES.some((prefix) => file.startsWith(prefix))
+}
+
 export const WINDOWS_PACKAGE_TESTS = [
   ...WINDOWS_BOUNDARY_TESTS,
   ...LINUX_PACKAGE_TESTS,