diff --git a/packages/contracts/package.json b/packages/contracts/package.json
index 47dbeded3d..9582f1ada8 100644
--- a/packages/contracts/package.json
+++ b/packages/contracts/package.json
@@ -352,6 +352,10 @@
       "types": "./src/platform-runtime-unavailable.ts",
       "default": "./src/platform-runtime-unavailable.ts"
     },
+    "./runtime-contract-error": {
+      "types": "./src/runtime-contract-error.ts",
+      "default": "./src/runtime-contract-error.ts"
+    },
     "./runtime-operation-names": {
       "types": "./src/runtime-operation-names.ts",
       "default": "./src/runtime-operation-names.ts"
diff --git a/packages/contracts/src/app-state-runtime.ts b/packages/contracts/src/app-state-runtime.ts
index 6b094ee6b1..0d74d91d18 100644
--- a/packages/contracts/src/app-state-runtime.ts
+++ b/packages/contracts/src/app-state-runtime.ts
@@ -1,6 +1,5 @@
 import type { AppleApplicationState } from '@agent-device/kernel/snapshot';
-
-export type { AppleApplicationState } from '@agent-device/kernel/snapshot';
+import type { LocalInteractorOperationResolver } from './interactor-operation-binding.ts';
 
 /** Which app a session-scoped read is about; the Android foreground read needs nothing. */
 export type AppStateRuntimeInput = Readonly<{ appBundleId?: string }>;
@@ -20,3 +19,6 @@ export type AppStateRuntimeResult = Readonly<{
 export type AppStateRuntimeOperations = Readonly<{
   appState(input?: AppStateRuntimeInput): Promise<AppStateRuntimeResult>;
 }>;
+
+/** Resolves the selected owner's interactor, as every other local interactor-backed read does. */
+export type AppStateInteractorResolver = LocalInteractorOperationResolver;
diff --git a/packages/contracts/src/app-state.ts b/packages/contracts/src/app-state.ts
index 6d339fe46d..81d1aa366d 100644
--- a/packages/contracts/src/app-state.ts
+++ b/packages/contracts/src/app-state.ts
@@ -1,4 +1,4 @@
-import type { AppleApplicationState } from './app-state-runtime.ts';
+import type { AppleApplicationState } from '@agent-device/kernel/snapshot';
 import type { SessionSurface } from './session-surface.ts';
 
 /**
diff --git a/packages/contracts/src/runtime-contract-error.ts b/packages/contracts/src/runtime-contract-error.ts
index 905227bf4f..ce7ac1ebe0 100644
--- a/packages/contracts/src/runtime-contract-error.ts
+++ b/packages/contracts/src/runtime-contract-error.ts
@@ -8,10 +8,11 @@ import { AppError } from '@agent-device/kernel/errors';
  * licenses a fallback, and the command then answers from stale data precisely because the
  * runtime lied about itself (ADR 0019 §2).
  *
- * Deliberately its own module rather than an export of `platform-runtime.ts`: the façade
- * re-exports that module and must stay exhaustive over it, which would make this a public
- * symbol with no external consumer — the unused-export defect. Here it stays internal to
- * `packages/contracts` and both runtime modules share one construction.
+ * Deliberately its own module rather than an export of `platform-runtime.ts`: that façade must stay
+ * exhaustive over its sources and keep its eager closure at budget, so it carries no leaf value
+ * symbol nobody in `contracts` consumes. This module stays a subpath of its own and imports nothing
+ * else from `contracts`, so a platform package whose facts advertised an operation its interactor
+ * cannot perform builds the same failure here instead of restating the code, reason, and hint.
  */
 export function invalidRuntimeContract(message: string): AppError {
   return new AppError('COMMAND_FAILED', message, {
diff --git a/packages/kernel/src/snapshot.ts b/packages/kernel/src/snapshot.ts
index c0d2af3147..7ce4fba3ed 100644
--- a/packages/kernel/src/snapshot.ts
+++ b/packages/kernel/src/snapshot.ts
@@ -471,32 +471,37 @@ export function isIosTargetActivationReason(value: unknown): value is IosTargetA
 }
 
 /**
- * States an activation could have been needed for, in `XCApplicationState` raw order: unknown 0,
- * notRunning 1, suspended 2, plain background 3 — the SDK declares suspended on non-macOS platforms
- * only. `runningForeground` is excluded because the runner skips `activate()` when the app is already
- * foreground and never stamps a fact there. The decoder, which assigns raw values, is what keeps this
- * order honest.
+ * How XCTest reports an app running (`XCUIApplication.State`), in the SDK's raw order: unknown 0,
+ * notRunning 1, suspended 2, plain background 3, foreground 4 — the SDK declares suspended on
+ * non-macOS platforms only. This is the one declaration of those names; the `appState` runner
+ * command answers the session app's state with them, and `RunnerTests+ApplicationStateRawValueTests`
+ * ties them to the SDK enum. The `appState` path names states, so nothing here assigns a raw value;
+ * only the activation decoder's raw table does.
  */
-export const IOS_TARGET_ACTIVATION_PRIOR_STATES = [
+export const APPLE_APPLICATION_STATES = [
   'unknown',
   'notRunning',
   'runningBackgroundSuspended',
   'runningBackground',
+  'runningForeground',
 ] as const;
 
-export type IosTargetActivationPriorState = (typeof IOS_TARGET_ACTIVATION_PRIOR_STATES)[number];
+export type AppleApplicationState = (typeof APPLE_APPLICATION_STATES)[number];
 
 /**
- * How XCTest reports an app running (`XCUIApplication.State`): the prior states above plus the
- * foreground state the activation disclosure never carries. The `appState` runner command names
- * the session app's state with these words.
+ * States an activation could have been needed for: every Apple state except the foreground one,
+ * which the runner skips `activate()` in and therefore stamps no fact about. Derived from the full
+ * list so the two cannot drift, and in the SDK's raw order — a state added to the full list lands
+ * here and must then be pinned natively before the decoder tie accepts it.
  */
-export const APPLE_APPLICATION_STATES = [
-  ...IOS_TARGET_ACTIVATION_PRIOR_STATES,
-  'runningForeground',
-] as const;
+export const IOS_TARGET_ACTIVATION_PRIOR_STATES = Object.freeze(
+  APPLE_APPLICATION_STATES.filter(
+    (state): state is Exclude<AppleApplicationState, 'runningForeground'> =>
+      state !== 'runningForeground',
+  ),
+);
 
-export type AppleApplicationState = (typeof APPLE_APPLICATION_STATES)[number];
+export type IosTargetActivationPriorState = (typeof IOS_TARGET_ACTIVATION_PRIOR_STATES)[number];
 
 export function isAppleApplicationState(value: unknown): value is AppleApplicationState {
   return (
diff --git a/packages/platform-apple/src/app-state-runtime.test.ts b/packages/platform-apple/src/app-state-runtime.test.ts
index 754426e7fa..bfa83dcbf3 100644
--- a/packages/platform-apple/src/app-state-runtime.test.ts
+++ b/packages/platform-apple/src/app-state-runtime.test.ts
@@ -13,9 +13,10 @@ const device: DeviceInfo = {
   booted: true,
 };
 
-function bind(liveRunner: boolean) {
+function bind(liveRunner: boolean, interactor?: Interactor) {
   const appState = vi.fn(async () => ({ applicationState: 'runningBackground' as const }));
-  const resolveInteractor = vi.fn(async () => ({ appState }) as unknown as Interactor);
+  const resolved: Interactor = interactor ?? ({ appState } as unknown as Interactor);
+  const resolveInteractor = vi.fn(async () => resolved);
   const hasLiveRunnerSession = vi.fn(async () => liveRunner);
   const operations = bindAppleAppStateRuntime(
     { appleApplications: { hasLiveRunnerSession } as never },
@@ -43,3 +44,19 @@ test('without a live runner session the read answers nothing and resolves no int
   expect(hasLiveRunnerSession).toHaveBeenCalledWith(device, {});
   expect(resolveInteractor).not.toHaveBeenCalled();
 });
+
+/**
+ * The facts promised `appState` and the interactor has none. Answering from the session record
+ * instead would invent a state the runner never read, so this fails as the contract bug it is
+ * (ADR 0019 §2) rather than degrading, and the typed reason is what keeps it outside every
+ * closed reason set that licenses a fallback.
+ */
+test('an advertised appState with no interactor implementation fails as a contract bug', async () => {
+  // An interactor with NO appState — the mismatch the facts promised away.
+  const { operations } = bind(true, {} as unknown as Interactor);
+  await expect(operations.appState({ appBundleId: 'com.example.app' })).rejects.toMatchObject({
+    code: 'COMMAND_FAILED',
+    message: expect.stringContaining('advertised appState'),
+    details: { reason: 'runtime-contract-invalid' },
+  });
+});
diff --git a/packages/platform-apple/src/app-state-runtime.ts b/packages/platform-apple/src/app-state-runtime.ts
index 8250a0602a..97f14860a4 100644
--- a/packages/platform-apple/src/app-state-runtime.ts
+++ b/packages/platform-apple/src/app-state-runtime.ts
@@ -1,18 +1,12 @@
 import type {
+  AppStateInteractorResolver,
   AppStateRuntimeInput,
   AppStateRuntimeOperations,
   AppStateRuntimeResult,
 } from '@agent-device/contracts/app-state-runtime';
-import type { Interactor, RunnerContext } from '@agent-device/contracts/interactor-types';
+import { invalidRuntimeContract } from '@agent-device/contracts/runtime-contract-error';
 import type { PlatformRuntimeHost } from '@agent-device/contracts/platform-runtime-operations';
 import type { DeviceInfo } from '@agent-device/kernel/device';
-import { AppError } from '@agent-device/kernel/errors';
-
-/** Resolves the selected owner's interactor, exactly as the element text runtime does. */
-export type AppStateInteractorResolver = (
-  device: DeviceInfo,
-  runner: RunnerContext,
-) => Promise<Interactor>;
 
 /**
  * Binds the runner's read of the session app's state for the lifetime of a request binding, on the
@@ -40,13 +34,8 @@ export function bindAppleAppStateRuntime(
       if (typeof interactor.appState !== 'function') {
         // Facts advertised the read but the interactor cannot perform it: a contract bug (ADR 0019
         // §2), not a refusal, so nothing upstream may answer from the session record instead.
-        throw new AppError(
-          'COMMAND_FAILED',
+        throw invalidRuntimeContract(
           'Runtime owner advertised appState without an interactor implementation',
-          {
-            reason: 'runtime-contract-invalid',
-            hint: 'This is an agent-device runtime contract bug; report the selected device and command.',
-          },
         );
       }
       return await interactor.appState();
diff --git a/scripts/layering/contracts-exports.snapshot.json b/scripts/layering/contracts-exports.snapshot.json
index 419ebc6e98..3095a7699e 100644
--- a/scripts/layering/contracts-exports.snapshot.json
+++ b/scripts/layering/contracts-exports.snapshot.json
@@ -95,6 +95,7 @@
   "@agent-device/contracts/remote",
   "@agent-device/contracts/replay",
   "@agent-device/contracts/runner-lease-context",
+  "@agent-device/contracts/runtime-contract-error",
   "@agent-device/contracts/runtime-operation-names",
   "@agent-device/contracts/screen-capture-contract",
   "@agent-device/contracts/screen-recording-runtime",
diff --git a/src/daemon/handlers/session-state.ts b/src/daemon/handlers/session-state.ts
index f74f7d7042..1b095e3bb5 100644
--- a/src/daemon/handlers/session-state.ts
+++ b/src/daemon/handlers/session-state.ts
@@ -16,7 +16,7 @@ import {
 import type { DaemonRequest, DaemonResponse } from '../daemon-request.ts';
 import { SessionStore } from '../session-store.ts';
 import { emitDiagnostic } from '@agent-device/host-kit/diagnostics';
-import type { AppleApplicationState } from '@agent-device/contracts/app-state-runtime';
+import type { AppleApplicationState } from '@agent-device/kernel/snapshot';
 import { resolveAndroidSerialAllowlist } from '@agent-device/kernel/device-isolation';
 import {
   hasExplicitSessionFlag,