diff --git a/.github/workflows/mobile.yml b/.github/workflows/mobile.yml
index 30dc63186e1..57ac9819d91 100644
--- a/.github/workflows/mobile.yml
+++ b/.github/workflows/mobile.yml
@@ -135,10 +135,10 @@ 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)
+        id: test-types
+        background: true
         run: node scripts/check-tests-typecheck-ratchet.mjs
 
-      - wait: production-types
-
       # 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:
       # it fails when a divergence class grows, when a divergence lands in no class at all, or when
@@ -168,6 +168,9 @@ jobs:
           ORCA_BACKGROUND_LAUNCH: '1'
         run: node ../config/scripts/run-mobile-ci-tests.mjs
 
+      # All checks read the completed install; compilers need not hold up test workers.
+      - wait: [production-types, test-types]
+
       # Reports, never gates: the goldens are content-addressed JSON, so their raw diff is hashes.
       # This decodes which recorded behaviour the pull request moves into the job summary, and runs
       # after a red Test too, when a reviewer most wants it.
diff --git a/config/scripts/mobile-test-change-scope.test.mjs b/config/scripts/mobile-test-change-scope.test.mjs
index 5e4e75b7685..7bdb513fd62 100644
--- a/config/scripts/mobile-test-change-scope.test.mjs
+++ b/config/scripts/mobile-test-change-scope.test.mjs
@@ -79,3 +79,29 @@ it('skips only tests, after successful detection, and retains all other mobile g
     expect(steps.find((step) => step.name === name).if).toBeUndefined()
   }
 })
+
+it('overlaps both typechecks with tests and collects their failures before the summary', () => {
+  const workflow = parse(
+    readFileSync(new URL('../../.github/workflows/mobile.yml', import.meta.url), 'utf8')
+  )
+  const steps = workflow.jobs.verify.steps
+  const install = steps.findIndex((step) => step.name === 'Install dependencies')
+  const test = steps.findIndex((step) => step.name === 'Test')
+  const summary = steps.findIndex((step) => step.name === 'Summarize RPC recording changes')
+  const waits = steps.filter((step) => step.wait !== undefined)
+  expect(waits).toHaveLength(1)
+  const [wait] = waits
+  expect(wait.wait).toEqual(['production-types', 'test-types'])
+  expect(wait.if).toBeUndefined()
+  expect(steps.indexOf(wait)).toBeGreaterThan(test)
+  expect(steps.indexOf(wait)).toBeLessThan(summary)
+  for (const id of wait.wait) {
+    const step = steps.find((candidate) => candidate.id === id)
+    expect(step.background).toBe(true)
+    expect(step['continue-on-error']).toBeUndefined()
+    expect(step.if).toBeUndefined()
+    expect(steps.indexOf(step)).toBeGreaterThan(install)
+    expect(steps.indexOf(step)).toBeLessThan(test)
+    expect(step.run).toMatch(/^node /)
+  }
+})
diff --git a/mobile/src/session/mobile-native-chat-merged-snapshot-parity.test.ts b/mobile/src/session/mobile-native-chat-merged-snapshot-parity.test.ts
index ae934923c72..89b22ac3461 100644
--- a/mobile/src/session/mobile-native-chat-merged-snapshot-parity.test.ts
+++ b/mobile/src/session/mobile-native-chat-merged-snapshot-parity.test.ts
@@ -221,11 +221,16 @@ describe.each(['after-end', 'during-turn'] as const)(
       ])
     })
 
-    it.each([1, 2, 3])('from every subscribe point, %i row(s) per frame', (rowsPerFrame) => {
-      expect(compareFrames(journal, range(2, journal.rows.length), rowsPerFrame).differing).toEqual(
-        []
-      )
-    })
+    // Exhaustive frame enumeration shares CI CPUs with the typechecks.
+    it.each([1, 2, 3])(
+      'from every subscribe point, %i row(s) per frame',
+      (rowsPerFrame) => {
+        expect(
+          compareFrames(journal, range(2, journal.rows.length), rowsPerFrame).differing
+        ).toEqual([])
+      },
+      10_000
+    )
   }
 )
 
diff --git a/mobile/src/test-support/rpc-recording/operation-module-loader-work-budget.test.ts b/mobile/src/test-support/rpc-recording/operation-module-loader-work-budget.test.ts
new file mode 100644
index 00000000000..e9dc9921883
--- /dev/null
+++ b/mobile/src/test-support/rpc-recording/operation-module-loader-work-budget.test.ts
@@ -0,0 +1,74 @@
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync, existsSync } from 'node:fs'
+import type * as FsModule from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, expect, it, vi } from 'vitest'
+import { nativeMountingSubstitutes } from './native-mounting-substitutes'
+import type * as NativeSubstitutesModule from './native-mounting-substitutes'
+import { operationModuleLoader } from './operation-module-loader'
+
+vi.mock('node:fs', async (original) => {
+  const fs = await original<typeof FsModule>()
+  return { ...fs, existsSync: vi.fn(fs.existsSync) }
+})
+
+vi.mock('./native-mounting-substitutes', async (original) => {
+  const module = await original<typeof NativeSubstitutesModule>()
+  return { ...module, nativeMountingSubstitutes: vi.fn(module.nativeMountingSubstitutes) }
+})
+
+const roots: string[] = []
+
+function sourceTree(files: Record<string, string>): string {
+  const root = mkdtempSync(join(tmpdir(), 'rpc-loader-work-budget-'))
+  roots.push(root)
+  mkdirSync(join(root, 'mobile', 'src'), { recursive: true })
+  for (const [name, source] of Object.entries(files)) {
+    writeFileSync(join(root, 'mobile', 'src', name), source)
+  }
+  return root
+}
+
+afterEach(() => {
+  for (const root of roots.splice(0)) {
+    rmSync(root, { recursive: true, force: true })
+  }
+  vi.clearAllMocks()
+})
+
+it('resolves a relative import once instead of probing disk on every exported member read', () => {
+  const root = sourceTree({
+    'value.ts': 'export const value = 42',
+    'operation.ts': `import { value } from './value'; export const read = () => value`
+  })
+  const operation = operationModuleLoader(root).load<{ read: () => number }>(
+    'mobile/src/operation.ts'
+  )
+  expect(operation.read()).toBe(42)
+  vi.mocked(existsSync).mockClear()
+  for (let index = 0; index < 1_000; index++) {
+    expect(operation.read()).toBe(42)
+  }
+  expect(existsSync).not.toHaveBeenCalled()
+})
+
+it('builds device substitutes only for a used loader and keeps their state per loader', async () => {
+  const root = sourceTree({
+    'operation.ts': `
+      import * as clipboard from 'expo-clipboard'
+      export const read = () => clipboard.getStringAsync()
+      export const write = () => clipboard.setStringAsync('first recording')
+    `
+  })
+  const loaders = Array.from({ length: 64 }, () => operationModuleLoader(root))
+  expect(nativeMountingSubstitutes).not.toHaveBeenCalled()
+  type ClipboardOperation = { read: () => Promise<string>; write: () => Promise<void> }
+  const first = loaders[0].load<ClipboardOperation>('mobile/src/operation.ts')
+  await first.write()
+  expect(await first.read()).toBe('first recording')
+  expect(nativeMountingSubstitutes).toHaveBeenCalledTimes(1)
+  const second = loaders[1].load<ClipboardOperation>('mobile/src/operation.ts')
+  expect(await second.read()).toBe('')
+  expect(await first.read()).toBe('first recording')
+  expect(nativeMountingSubstitutes).toHaveBeenCalledTimes(2)
+})
diff --git a/mobile/src/test-support/rpc-recording/operation-module-loader.ts b/mobile/src/test-support/rpc-recording/operation-module-loader.ts
index b2f75a4cb4f..ae0ec820b51 100644
--- a/mobile/src/test-support/rpc-recording/operation-module-loader.ts
+++ b/mobile/src/test-support/rpc-recording/operation-module-loader.ts
@@ -32,7 +32,7 @@ export function operationModuleLoader(
   declared: ReadonlyMap<string, unknown> = new Map()
 ) {
   const cache = new Map<string, OperationModule>()
-  const natives = new Map([...nativeMountingSubstitutes(), ...declared])
+  let natives: Map<string, unknown> | undefined
   const sharedModulePath = resolve(root, SHARED_MODULE)
   let mutationCount = 0
   function pathFor(base: string): string {
@@ -45,13 +45,12 @@ export function operationModuleLoader(
     return file
   }
   function imported(base: string, name: string): unknown {
+    // Most registered adapters are never mounted in this recording.
+    natives ??= new Map([...nativeMountingSubstitutes(), ...declared])
     const native = natives.get(name)
     if (native !== undefined) {
       return native
     }
-    if (name.startsWith('.') && pathFor(resolve(dirname(base), name)) === sharedModulePath) {
-      return deliveryAmbiguity
-    }
     if (!name.startsWith('.')) {
       return new Proxy(
         {},
@@ -69,10 +68,11 @@ export function operationModuleLoader(
         }
       )
     }
-    return new Proxy(
-      {},
-      { get: (_target, key) => load(pathFor(resolve(dirname(base), name)))[String(key)] }
-    )
+    const file = pathFor(resolve(dirname(base), name))
+    if (file === sharedModulePath) {
+      return deliveryAmbiguity
+    }
+    return new Proxy({}, { get: (_target, key) => load(file)[String(key)] })
   }
   function barrel(file: string, source: string): OperationModule {
     const parsed = ts.createSourceFile(file, source, ts.ScriptTarget.Latest, true)