diff --git a/.github/workflows/mobile.yml b/.github/workflows/mobile.yml
index f17c7e8f1d7..ae695b8e3eb 100644
--- a/.github/workflows/mobile.yml
+++ b/.github/workflows/mobile.yml
@@ -114,11 +114,11 @@ jobs:
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
 
-      # pnpm entrypoints can auto-install; finish each before the next mutates node_modules.
+      # Call installed tools so pnpm's dependency refresh cannot race between checks.
       - name: Typecheck
         id: production-types
         background: true
-        run: pnpm typecheck
+        run: node node_modules/typescript/bin/tsc --noEmit
 
       - wait: production-types
 
@@ -127,7 +127,7 @@ jobs:
       # drifted. This fails when a test file that checks today stops checking, when a test leaves
       # the program, and on @ts-nocheck; the baseline may only shrink.
       - name: Typecheck tests (ratchet)
-        run: pnpm run check:tests-typecheck
+        run: node scripts/check-tests-typecheck-ratchet.mjs
 
       # This includes the bridged replay of the whole recording corpus, which used to be a second
       # step of its own behind RPC_FOUNDATION_BRIDGE=1. A gate nobody can forget to set is the point:
diff --git a/config/scripts/mobile-typecheck-workflow.test.mjs b/config/scripts/mobile-typecheck-workflow.test.mjs
new file mode 100644
index 00000000000..0ab57ad858f
--- /dev/null
+++ b/config/scripts/mobile-typecheck-workflow.test.mjs
@@ -0,0 +1,42 @@
+import { readFileSync } from 'node:fs'
+import { describe, expect, it } from 'vitest'
+import { parse } from 'yaml'
+
+const workflow = parse(readFileSync('.github/workflows/mobile.yml', 'utf8'))
+const packageJson = JSON.parse(readFileSync('mobile/package.json', 'utf8'))
+const job = workflow.jobs.verify
+const steps = job.steps
+
+describe('mobile verification command ownership', () => {
+  it('runs the declared checks through installed tools without a script-time install', () => {
+    const production = steps.find((step) => step.name === 'Typecheck')
+    const tests = steps.find((step) => step.name === 'Typecheck tests (ratchet)')
+
+    expect(packageJson.scripts.typecheck).toMatch(/^tsc\b/)
+    expect(production.run).toBe(`node node_modules/typescript/bin/${packageJson.scripts.typecheck}`)
+    expect(tests.run).toBe(packageJson.scripts['check:tests-typecheck'])
+    expect(tests.run).toMatch(/^node\s/)
+    expect(job.defaults.run['working-directory']).toBe('mobile')
+    for (const name of ['typecheck', 'check:tests-typecheck']) {
+      expect(packageJson.scripts[`pre${name}`]).toBeUndefined()
+      expect(packageJson.scripts[`post${name}`]).toBeUndefined()
+    }
+  })
+
+  it('finishes installation and joins production types before checking test types', () => {
+    const installIndex = steps.findIndex((step) => step.name === 'Install dependencies')
+    const productionIndex = steps.findIndex((step) => step.name === 'Typecheck')
+    const ratchetIndex = steps.findIndex((step) => step.name === 'Typecheck tests (ratchet)')
+    const waitIndex = steps.findIndex((step) => step.wait === steps[productionIndex].id)
+    const testIndex = steps.findIndex((step) => step.name === 'Test')
+
+    expect(steps[installIndex].run).toBe('pnpm install --frozen-lockfile')
+    expect(steps[installIndex].background ?? false).toBe(false)
+    expect(installIndex).toBeLessThan(productionIndex)
+    expect(steps[productionIndex].background).toBe(true)
+    expect(productionIndex).toBeLessThan(ratchetIndex)
+    expect(waitIndex).toBeGreaterThan(productionIndex)
+    expect(waitIndex).toBeLessThan(ratchetIndex)
+    expect(ratchetIndex).toBeLessThan(testIndex)
+  })
+})
diff --git a/config/scripts/pr-e2e-gate-contract.test.mjs b/config/scripts/pr-e2e-gate-contract.test.mjs
index caec90ee086..2e8b77fd97c 100644
--- a/config/scripts/pr-e2e-gate-contract.test.mjs
+++ b/config/scripts/pr-e2e-gate-contract.test.mjs
@@ -1,4 +1,5 @@
 import { DEDICATED_E2E_SPECS } from './ci-e2e-job-selection.mjs'
+import { linuxInstallPackageList } from './pr-e2e-linux-packages.test-fixture.mjs'
 import { existsSync, readdirSync, readFileSync } from 'node:fs'
 import { join, resolve } from 'node:path'
 import { parse as parseJsonc } from 'jsonc-parser'
@@ -20,6 +21,7 @@ import {
 const projectDir = resolve(import.meta.dirname, '../..')
 const prWorkflow = parseYaml(readFileSync(join(projectDir, '.github/workflows/pr.yml'), 'utf8'))
 const e2eWorkflow = parseYaml(readFileSync(join(projectDir, '.github/workflows/e2e.yml'), 'utf8'))
+
 const reliabilityManifest = parseJsonc(
   readFileSync(join(projectDir, 'config/reliability-gates.jsonc'), 'utf8')
 )
@@ -218,7 +220,7 @@ describe('PR E2E gate contract', () => {
       const installStep = e2eWorkflow.jobs[jobName].steps.find((step) =>
         step.name.startsWith('Install native build')
       )
-      expect(installStep.env.ORCA_E2E_APT_PACKAGES.split(/\s+/), jobName).toContain('zsh')
+      expect(linuxInstallPackageList(installStep, jobName), jobName).toMatch(/\bzsh\b/)
     }
   })
 
@@ -308,7 +310,7 @@ describe('PR E2E gate contract', () => {
     const changedInstall = e2eWorkflow.jobs['changed-e2e'].steps.find((step) =>
       step.name.startsWith('Install native build')
     )
-    expect(changedInstall.env.ORCA_E2E_APT_PACKAGES.split(/\s+/)).toContain('openssh-client')
+    expect(linuxInstallPackageList(changedInstall, 'changed-e2e')).toMatch(/\bopenssh-client\b/)
   })
 
   it('routes direct-SSH workspace and tab restore from its unnamed source seams', () => {
diff --git a/config/scripts/pr-e2e-linux-packages.test-fixture.mjs b/config/scripts/pr-e2e-linux-packages.test-fixture.mjs
new file mode 100644
index 00000000000..dfbb2d4b798
--- /dev/null
+++ b/config/scripts/pr-e2e-linux-packages.test-fixture.mjs
@@ -0,0 +1,10 @@
+import { expect } from 'vitest'
+
+export function linuxInstallPackageList(step, jobName) {
+  const packages = step.env?.ORCA_E2E_APT_PACKAGES
+  if (packages !== undefined) {
+    expect(step.run, jobName).toContain('read -r -a packages <<< "$ORCA_E2E_APT_PACKAGES"')
+    expect(step.run, jobName).toContain('sudo apt-get install -y "${packages[@]}"')
+  }
+  return packages ?? step.run
+}