diff --git a/src/client-types.ts b/src/client-types.ts
index 02a304364..0e2295894 100644
--- a/src/client-types.ts
+++ b/src/client-types.ts
@@ -356,8 +356,6 @@ export type CaptureScreenshotResult = {
 
 export type DeviceCommandBaseOptions = AgentDeviceRequestOverrides & AgentDeviceSelectionOptions;
 
-type WaitSnapshotOptions = Pick<CaptureSnapshotOptions, 'depth' | 'scope' | 'raw'>;
-
 type WaitCommandTarget =
   | {
       durationMs: number;
@@ -366,21 +364,21 @@ type WaitCommandTarget =
       selector?: never;
       timeoutMs?: never;
     }
-  | (WaitSnapshotOptions & {
+  | (SelectorSnapshotCommandOptions & {
       text: string;
       durationMs?: never;
       ref?: never;
       selector?: never;
       timeoutMs?: number;
     })
-  | (WaitSnapshotOptions & {
+  | (SelectorSnapshotCommandOptions & {
       ref: string;
       durationMs?: never;
       text?: never;
       selector?: never;
       timeoutMs?: number;
     })
-  | (WaitSnapshotOptions & {
+  | (SelectorSnapshotCommandOptions & {
       selector: string;
       durationMs?: never;
       text?: never;
@@ -493,11 +491,11 @@ export type ClipboardCommandResult =
       textLength: number;
     });
 
-export type ReactNativeCommandOptions = ClientCommandBaseOptions & {
+export type ReactNativeCommandOptions = DeviceCommandBaseOptions & {
   action: 'dismiss-overlay';
 };
 
-export type PrepareCommandOptions = ClientCommandBaseOptions & {
+export type PrepareCommandOptions = DeviceCommandBaseOptions & {
   action: 'ios-runner';
   timeoutMs?: number;
 };
@@ -519,8 +517,6 @@ export type AgentDeviceCommandClient = {
 type SelectorSnapshotCommandOptions = Pick<CaptureSnapshotOptions, 'depth' | 'scope' | 'raw'>;
 type FindSnapshotCommandOptions = Pick<CaptureSnapshotOptions, 'depth' | 'raw'>;
 
-type ClientCommandBaseOptions = AgentDeviceRequestOverrides & AgentDeviceSelectionOptions;
-
 type PointTarget = {
   x: number;
   y: number;
@@ -557,47 +553,47 @@ type RepeatedPressOptions = {
   doubleTap?: boolean;
 };
 
-export type DeviceBootOptions = ClientCommandBaseOptions & {
+export type DeviceBootOptions = DeviceCommandBaseOptions & {
   headless?: boolean;
 };
 
-export type DeviceShutdownOptions = ClientCommandBaseOptions;
+export type DeviceShutdownOptions = DeviceCommandBaseOptions;
 
-export type AppPushOptions = ClientCommandBaseOptions & {
+export type AppPushOptions = DeviceCommandBaseOptions & {
   app: string;
   payload: string | Record<string, unknown>;
 };
 
-export type AppTriggerEventOptions = ClientCommandBaseOptions & {
+export type AppTriggerEventOptions = DeviceCommandBaseOptions & {
   event: string;
   payload?: Record<string, unknown>;
 };
 
-export type CaptureDiffOptions = ClientCommandBaseOptions &
+export type CaptureDiffOptions = DeviceCommandBaseOptions &
   Pick<CaptureSnapshotOptions, 'interactiveOnly' | 'compact' | 'depth' | 'scope' | 'raw'> & {
     kind: 'snapshot';
     out?: string;
   };
 
-export type ClickOptions = ClientCommandBaseOptions &
+export type ClickOptions = DeviceCommandBaseOptions &
   SelectorSnapshotCommandOptions &
   InteractionTarget &
   RepeatedPressOptions & {
     button?: ClickButton;
   };
 
-export type PressOptions = ClientCommandBaseOptions &
+export type PressOptions = DeviceCommandBaseOptions &
   SelectorSnapshotCommandOptions &
   InteractionTarget &
   RepeatedPressOptions;
 
-export type LongPressOptions = ClientCommandBaseOptions &
+export type LongPressOptions = DeviceCommandBaseOptions &
   SelectorSnapshotCommandOptions &
   InteractionTarget & {
     durationMs?: number;
   };
 
-export type SwipeOptions = ClientCommandBaseOptions & {
+export type SwipeOptions = DeviceCommandBaseOptions & {
   from: { x: number; y: number };
   to: { x: number; y: number };
   durationMs?: number;
@@ -606,7 +602,7 @@ export type SwipeOptions = ClientCommandBaseOptions & {
   pattern?: SwipePattern;
 };
 
-export type PanOptions = ClientCommandBaseOptions & {
+export type PanOptions = DeviceCommandBaseOptions & {
   x: number;
   y: number;
   dx: number;
@@ -614,7 +610,7 @@ export type PanOptions = ClientCommandBaseOptions & {
   durationMs?: number;
 };
 
-export type FlingOptions = ClientCommandBaseOptions & {
+export type FlingOptions = DeviceCommandBaseOptions & {
   direction: ScrollDirection;
   x: number;
   y: number;
@@ -622,63 +618,63 @@ export type FlingOptions = ClientCommandBaseOptions & {
   durationMs?: number;
 };
 
-export type SwipeGestureOptions = ClientCommandBaseOptions & {
+export type SwipeGestureOptions = DeviceCommandBaseOptions & {
   preset: SwipePreset;
   durationMs?: number;
 };
 
-export type FocusOptions = ClientCommandBaseOptions & {
+export type FocusOptions = DeviceCommandBaseOptions & {
   x: number;
   y: number;
 };
 
-export type TypeTextOptions = ClientCommandBaseOptions & {
+export type TypeTextOptions = DeviceCommandBaseOptions & {
   text: string;
   delayMs?: number;
 };
 
-export type FillOptions = ClientCommandBaseOptions &
+export type FillOptions = DeviceCommandBaseOptions &
   SelectorSnapshotCommandOptions &
   InteractionTarget & {
     text: string;
     delayMs?: number;
   };
 
-export type ScrollOptions = ClientCommandBaseOptions & {
+export type ScrollOptions = DeviceCommandBaseOptions & {
   direction: ScrollInputDirection;
   amount?: number;
   pixels?: number;
 };
 
-export type PinchOptions = ClientCommandBaseOptions & {
+export type PinchOptions = DeviceCommandBaseOptions & {
   scale: number;
   x?: number;
   y?: number;
 };
 
-export type RotateGestureOptions = ClientCommandBaseOptions & {
+export type RotateGestureOptions = DeviceCommandBaseOptions & {
   degrees: number;
   x?: number;
   y?: number;
   velocity?: number;
 };
 
-export type TransformGestureOptions = ClientCommandBaseOptions & TransformGestureParams;
+export type TransformGestureOptions = DeviceCommandBaseOptions & TransformGestureParams;
 
-export type GetOptions = ClientCommandBaseOptions &
+export type GetOptions = DeviceCommandBaseOptions &
   SelectorSnapshotCommandOptions &
   ElementTarget & {
     format: 'text' | 'attrs';
   };
 
-type IsTextPredicateOptions = ClientCommandBaseOptions &
+type IsTextPredicateOptions = DeviceCommandBaseOptions &
   SelectorSnapshotCommandOptions & {
     predicate: 'text';
     selector: string;
     value: string;
   };
 
-type IsStatePredicateOptions = ClientCommandBaseOptions &
+type IsStatePredicateOptions = DeviceCommandBaseOptions &
   SelectorSnapshotCommandOptions & {
     predicate: 'visible' | 'hidden' | 'exists' | 'editable' | 'selected';
     selector: string;
@@ -687,7 +683,7 @@ type IsStatePredicateOptions = ClientCommandBaseOptions &
 
 export type IsOptions = IsTextPredicateOptions | IsStatePredicateOptions;
 
-type FindBaseOptions = ClientCommandBaseOptions &
+type FindBaseOptions = DeviceCommandBaseOptions &
   FindSnapshotCommandOptions & {
     locator?: FindLocator;
     query: string;
@@ -742,7 +738,7 @@ export type BatchRunOptions = AgentDeviceRequestOverrides & {
   out?: string;
 };
 
-export type PerfOptions = ClientCommandBaseOptions & {
+export type PerfOptions = DeviceCommandBaseOptions & {
   area?: PerfArea;
   action?: PerfAction;
 };
@@ -793,38 +789,38 @@ export type PermissionTarget =
   | 'input-monitoring';
 
 export type SettingsUpdateOptions =
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'clear-app-state';
       state: 'clear';
       app?: string;
     })
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'wifi' | 'airplane' | 'location';
       state: 'on' | 'off';
     })
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'location';
       state: 'set';
       latitude: number;
       longitude: number;
     })
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'animations';
       state: 'on' | 'off';
     })
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'appearance';
       state: 'light' | 'dark' | 'toggle';
     })
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'faceid' | 'touchid';
       state: 'match' | 'nonmatch' | 'enroll' | 'unenroll';
     })
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'fingerprint';
       state: 'match' | 'nonmatch';
     })
-  | (ClientCommandBaseOptions & {
+  | (DeviceCommandBaseOptions & {
       setting: 'permission';
       state: 'grant' | 'deny' | 'reset';
       permission: PermissionTarget;
diff --git a/src/commands/perf-command-contract.ts b/src/commands/perf-command-contract.ts
index e332aa07e..63a4b7e14 100644
--- a/src/commands/perf-command-contract.ts
+++ b/src/commands/perf-command-contract.ts
@@ -1,3 +1,5 @@
+import { isStringMember } from '../utils/string-enum.ts';
+
 export const PERF_AREA_VALUES = ['metrics', 'frames'] as const;
 export const PERF_ACTION_VALUES = ['sample'] as const;
 
@@ -8,9 +10,9 @@ export const PERF_AREA_ERROR_MESSAGE = 'perf area must be metrics or frames';
 export const PERF_ACTION_ERROR_MESSAGE = 'perf action must be sample';
 
 export function isPerfArea(value: string): value is PerfArea {
-  return (PERF_AREA_VALUES as readonly string[]).includes(value);
+  return isStringMember(PERF_AREA_VALUES, value);
 }
 
 export function isPerfAction(value: string): value is PerfAction {
-  return (PERF_ACTION_VALUES as readonly string[]).includes(value);
+  return isStringMember(PERF_ACTION_VALUES, value);
 }
diff --git a/src/core/dispatch-interactions.ts b/src/core/dispatch-interactions.ts
index a2982b396..bfd07e6c3 100644
--- a/src/core/dispatch-interactions.ts
+++ b/src/core/dispatch-interactions.ts
@@ -7,11 +7,14 @@ import {
   inferGestureReferenceFrame,
   parseScrollDirection,
   parseSwipePreset,
+  SCROLL_DIRECTIONS,
+  SWIPE_PATTERNS,
   type ScrollDirection,
   type SwipePattern,
   type SwipePreset,
   type TransformGestureParams,
 } from './scroll-gesture.ts';
+import { isStringMember, parseStringMember } from '../utils/string-enum.ts';
 import {
   getClickButtonValidationError,
   resolveClickButton,
@@ -32,7 +35,7 @@ import {
   runRepeatedSeries,
 } from './dispatch-series.ts';
 import type { DispatchContext } from './dispatch-context.ts';
-import type { Interactor } from './interactor-types.ts';
+import type { Interactor, RunnerCallOptions } from './interactor-types.ts';
 
 export async function handleLongPressCommand(
   interactor: Interactor,
@@ -386,12 +389,7 @@ async function runDirectPressSeries(
   );
 }
 
-function runnerOptionsFromContext(context: DispatchContext | undefined): {
-  verbose?: boolean;
-  logPath?: string;
-  traceLogPath?: string;
-  requestId?: string;
-} {
+function runnerOptionsFromContext(context: DispatchContext | undefined): RunnerCallOptions {
   return {
     verbose: context?.verbose,
     logPath: context?.logPath,
@@ -472,7 +470,7 @@ async function runSwipeCoordinates(params: {
   const count = requireIntInRange(context?.count ?? 1, 'count', 1, 200);
   const pauseMs = requireIntInRange(context?.pauseMs ?? 0, 'pause-ms', 0, 10_000);
   const pattern = context?.pattern ?? 'one-way';
-  if (pattern !== 'one-way' && pattern !== 'ping-pong') {
+  if (!isStringMember(SWIPE_PATTERNS, pattern)) {
     throw new AppError('INVALID_ARGS', `Invalid pattern: ${pattern}`);
   }
 
@@ -832,10 +830,9 @@ function parseOptionalGestureCenter(
 }
 
 function parseGestureDirection(input: string | undefined, field: string): ScrollDirection {
-  if (input === 'up' || input === 'down' || input === 'left' || input === 'right') {
-    return input;
-  }
-  throw new AppError('INVALID_ARGS', `${field} must be up, down, left, or right`);
+  return parseStringMember(SCROLL_DIRECTIONS, input, {
+    message: `${field} must be up, down, left, or right`,
+  });
 }
 
 function requireFinitePositiveNumber(value: number, field: string): number {
diff --git a/src/core/interactor-types.ts b/src/core/interactor-types.ts
index 24c22bcfd..9966d2cca 100644
--- a/src/core/interactor-types.ts
+++ b/src/core/interactor-types.ts
@@ -18,6 +18,12 @@ export type RunnerContext = {
   traceLogPath?: string;
 };
 
+/** Subset of {@link RunnerContext} forwarded to runner command invocations. */
+export type RunnerCallOptions = Pick<
+  RunnerContext,
+  'verbose' | 'logPath' | 'traceLogPath' | 'requestId'
+>;
+
 export type { BackMode };
 
 export type ScreenshotOptions = {
diff --git a/src/core/scroll-gesture.ts b/src/core/scroll-gesture.ts
index aaffba7c0..8ba6beef5 100644
--- a/src/core/scroll-gesture.ts
+++ b/src/core/scroll-gesture.ts
@@ -1,4 +1,5 @@
 import { AppError } from '../utils/errors.ts';
+import { parseStringMember } from '../utils/string-enum.ts';
 import type { Rect, SnapshotNode } from '../utils/snapshot.ts';
 
 export const SCROLL_DIRECTIONS = ['up', 'down', 'left', 'right'] as const;
@@ -149,18 +150,9 @@ export function buildSwipePresetGesturePlan(
 }
 
 export function parseSwipePreset(input: string | undefined): SwipePreset {
-  switch (input) {
-    case 'left':
-    case 'right':
-    case 'left-edge':
-    case 'right-edge':
-      return input;
-    default:
-      throw new AppError(
-        'INVALID_ARGS',
-        'gesture swipe requires left, right, left-edge, or right-edge',
-      );
-  }
+  return parseStringMember(SWIPE_PRESETS, input, {
+    message: 'gesture swipe requires left, right, left-edge, or right-edge',
+  });
 }
 
 export function inferGestureReferenceFrame(
@@ -200,15 +192,9 @@ export function clampGesturePoint(
 }
 
 export function parseScrollDirection(direction: string): ScrollDirection {
-  switch (direction) {
-    case 'up':
-    case 'down':
-    case 'left':
-    case 'right':
-      return direction;
-    default:
-      throw new AppError('INVALID_ARGS', `Unknown direction: ${direction}`);
-  }
+  return parseStringMember(SCROLL_DIRECTIONS, direction, {
+    message: `Unknown direction: ${direction}`,
+  });
 }
 
 function scrollDirectionForFingerSwipe(direction: ScrollDirection): ScrollDirection {
diff --git a/src/core/session-surface.ts b/src/core/session-surface.ts
index cd57a5899..711b48da3 100644
--- a/src/core/session-surface.ts
+++ b/src/core/session-surface.ts
@@ -1,20 +1,11 @@
-import { AppError } from '../utils/errors.ts';
+import { parseStringMember } from '../utils/string-enum.ts';
 
 export const SESSION_SURFACES = ['app', 'frontmost-app', 'desktop', 'menubar'] as const;
 export type SessionSurface = (typeof SESSION_SURFACES)[number];
 
 export function parseSessionSurface(value: string | undefined): SessionSurface {
-  const normalized = value?.trim().toLowerCase();
-  if (
-    normalized === 'app' ||
-    normalized === 'frontmost-app' ||
-    normalized === 'desktop' ||
-    normalized === 'menubar'
-  ) {
-    return normalized;
-  }
-  throw new AppError(
-    'INVALID_ARGS',
-    `Invalid surface: ${value}. Use ${SESSION_SURFACES.join('|')}.`,
-  );
+  return parseStringMember(SESSION_SURFACES, value, {
+    normalize: (raw) => raw.trim().toLowerCase(),
+    message: `Invalid surface: ${value}. Use ${SESSION_SURFACES.join('|')}.`,
+  });
 }
diff --git a/src/daemon/app-log-process.ts b/src/daemon/app-log-process.ts
index e507508e6..c9686d0de 100644
--- a/src/daemon/app-log-process.ts
+++ b/src/daemon/app-log-process.ts
@@ -1,7 +1,7 @@
 import fs from 'node:fs';
 import path from 'node:path';
 import { readProcessCommand, readProcessStartTime } from '../utils/process-identity.ts';
-import type { NetworkLogBackend } from './network-log.ts';
+import type { LogBackend } from './network-log.ts';
 import type { ExecResult } from '../utils/exec.ts';
 
 export const APP_LOG_PID_FILENAME = 'app-log.pid';
@@ -9,7 +9,7 @@ export const APP_LOG_PID_FILENAME = 'app-log.pid';
 export type AppLogState = 'active' | 'recovering' | 'failed';
 
 export type AppLogResult = {
-  backend: NetworkLogBackend;
+  backend: LogBackend;
   getState: () => AppLogState;
   startedAt: number;
   stop: () => Promise<void>;
diff --git a/src/daemon/app-log-stream.ts b/src/daemon/app-log-stream.ts
index 59229ecb1..6ab3b4585 100644
--- a/src/daemon/app-log-stream.ts
+++ b/src/daemon/app-log-stream.ts
@@ -21,10 +21,12 @@ function redactChunk(chunk: string, patterns: RegExp[]): string {
   return output;
 }
 
+type LineWriter = { onChunk: (chunk: string) => void; flush: () => void };
+
 export function createLineWriter(
   stream: fs.WriteStream,
   options: { redactionPatterns: RegExp[]; includeTokens?: string[] },
-): { onChunk: (chunk: string) => void; flush: () => void } {
+): LineWriter {
   const includeTokens = options.includeTokens?.filter((token) => token.length > 0) ?? [];
   let pending = '';
 
@@ -67,7 +69,7 @@ export function attachChildToStream(
   stream: fs.WriteStream,
   options: {
     endStreamOnClose: boolean;
-    writer: { onChunk: (chunk: string) => void; flush: () => void };
+    writer: LineWriter;
   },
 ): Promise<ExecResult> {
   const stdout = child.stdout;
diff --git a/src/daemon/app-log.ts b/src/daemon/app-log.ts
index 2229d9783..745180eb3 100644
--- a/src/daemon/app-log.ts
+++ b/src/daemon/app-log.ts
@@ -27,7 +27,7 @@ import {
   readRecentNetworkTrafficFromText,
   type NetworkDump,
   type NetworkIncludeMode,
-  type NetworkLogBackend,
+  type LogBackend,
 } from './network-log.ts';
 
 export type { AppLogResult } from './app-log-process.ts';
@@ -49,7 +49,7 @@ export type AppLogDoctorResult = {
 };
 
 export type SessionNetworkCapture = {
-  backend: NetworkLogBackend;
+  backend: LogBackend;
   dump: NetworkDump;
   notes: string[];
 };
@@ -176,7 +176,7 @@ export function getAppLogPathMetadata(outPath: string): {
   };
 }
 
-function resolveNetworkLogBackend(device: DeviceInfo): NetworkLogBackend {
+export function resolveLogBackend(device: DeviceInfo): LogBackend {
   if (device.platform === 'macos') return 'macos';
   if (device.platform === 'ios') {
     return device.kind === 'device' ? 'ios-device' : 'ios-simulator';
@@ -206,7 +206,7 @@ export async function readSessionNetworkCapture(params: {
     maxPayloadChars,
     maxScanLines,
   } = params;
-  const backend = resolveNetworkLogBackend(device);
+  const backend = resolveLogBackend(device);
   let dump = readRecentNetworkTraffic(appLogPath, {
     backend,
     maxEntries,
diff --git a/src/daemon/direct-ios-selector.ts b/src/daemon/direct-ios-selector.ts
index bf91a962c..a7b8f6114 100644
--- a/src/daemon/direct-ios-selector.ts
+++ b/src/daemon/direct-ios-selector.ts
@@ -1,14 +1,9 @@
 import type { SessionState } from './types.ts';
 import { tryParseSelectorChain } from './selectors.ts';
 import { asAppError } from '../utils/errors.ts';
-import type { ElementSelectorKey } from '../core/interactor-types.ts';
+import type { ElementSelectorTapOptions } from '../core/interactor-types.ts';
 
-export type DirectIosSelectorTarget = {
-  key: ElementSelectorKey;
-  value: string;
-  raw: string;
-  allowNonHittableCoordinateFallback?: boolean;
-};
+export type DirectIosSelectorTarget = ElementSelectorTapOptions & { raw: string };
 
 export function readSimpleIosSelectorTarget(params: {
   session: SessionState | undefined;
diff --git a/src/daemon/handlers/session-observability.ts b/src/daemon/handlers/session-observability.ts
index 0ba4a0442..10f734381 100644
--- a/src/daemon/handlers/session-observability.ts
+++ b/src/daemon/handlers/session-observability.ts
@@ -14,6 +14,7 @@ import {
   clearAppLogFiles,
   getAppLogPathMetadata,
   readSessionNetworkCapture,
+  resolveLogBackend,
   runAppLogDoctor,
   startAppLog,
   stopAppLog,
@@ -21,7 +22,7 @@ import {
 import { buildPerfFramesResponseData, buildPerfResponseData } from './session-perf.ts';
 import { errorResponse, type DaemonFailureResponse } from './response.ts';
 import type { NetworkIncludeMode } from '../../contracts.ts';
-import type { NetworkLogBackend } from '../network-log.ts';
+import type { LogBackend } from '../network-log.ts';
 import {
   LOG_ACTION_VALUES as LOG_ACTIONS,
   type LogAction as LogsAction,
@@ -66,17 +67,8 @@ const LOG_ACTION_HANDLERS: Record<
     handleLogsStop(session, sessionName, sessionStore),
 };
 
-function resolveSessionLogBackendLabel(session: SessionState): NetworkLogBackend {
-  if (session.appLog) {
-    return session.appLog.backend;
-  }
-  if (session.device.platform === 'macos') {
-    return 'macos';
-  }
-  if (session.device.platform === 'ios') {
-    return session.device.kind === 'device' ? 'ios-device' : 'ios-simulator';
-  }
-  return 'android';
+function resolveSessionLogBackendLabel(session: SessionState): LogBackend {
+  return session.appLog?.backend ?? resolveLogBackend(session.device);
 }
 
 export async function handleSessionObservabilityCommands(
diff --git a/src/daemon/interaction-outcome-policy.ts b/src/daemon/interaction-outcome-policy.ts
index 1f3edd98f..f0e079020 100644
--- a/src/daemon/interaction-outcome-policy.ts
+++ b/src/daemon/interaction-outcome-policy.ts
@@ -146,13 +146,9 @@ export function stripInternalInteractionFlags(
   return publicFlags;
 }
 
-export function buildInteractionSurfaceSignature(nodes: SnapshotNode[]): Array<{
-  key: string;
-  x: number;
-  y: number;
-  width: number;
-  height: number;
-}> {
+export function buildInteractionSurfaceSignature(
+  nodes: SnapshotNode[],
+): InteractionSurfaceSignature {
   const occurrenceCounts = new Map<string, number>();
   const entries: InteractionSurfaceSignature = [];
 
diff --git a/src/daemon/network-log.ts b/src/daemon/network-log.ts
index b38b8bbb1..f15421d26 100644
--- a/src/daemon/network-log.ts
+++ b/src/daemon/network-log.ts
@@ -20,7 +20,7 @@ const NETWORK_LOG_MEMORY_PATH = '<memory>';
 
 import type { NetworkIncludeMode } from '../contracts.ts';
 export type { NetworkIncludeMode };
-export type NetworkLogBackend = 'ios-simulator' | 'ios-device' | 'android' | 'macos';
+export type LogBackend = 'ios-simulator' | 'ios-device' | 'android' | 'macos';
 
 export type NetworkEntry = {
   method?: string;
@@ -74,7 +74,7 @@ export function mergeNetworkDumps(
 export function readRecentNetworkTraffic(
   logPath: string,
   options?: {
-    backend?: NetworkLogBackend;
+    backend?: LogBackend;
     maxEntries?: number;
     include?: NetworkIncludeMode;
     maxPayloadChars?: number;
@@ -108,7 +108,7 @@ export function readRecentNetworkTrafficFromText(
   content: string,
   options?: {
     path?: string;
-    backend?: NetworkLogBackend;
+    backend?: LogBackend;
     maxEntries?: number;
     include?: NetworkIncludeMode;
     maxPayloadChars?: number;
@@ -156,7 +156,7 @@ function parseNetworkLine(
   lines: string[],
   lineIndex: number,
   lineNumber: number,
-  backend: NetworkLogBackend | undefined,
+  backend: LogBackend | undefined,
   include: NetworkIncludeMode,
   maxPayloadChars: number,
 ): NetworkEntry | null {
diff --git a/src/daemon/selector-runtime.ts b/src/daemon/selector-runtime.ts
index b9e8525bf..def89f7fa 100644
--- a/src/daemon/selector-runtime.ts
+++ b/src/daemon/selector-runtime.ts
@@ -80,9 +80,11 @@ type DirectIosSelectorQueryResult = {
   node?: SnapshotNode;
 };
 
+type DirectIosSelectorErrorResult = { kind: 'error'; response: DaemonResponse };
+
 type DirectIosSelectorFallbackResult =
   | DirectIosSelectorQueryResult
-  | { kind: 'error'; response: DaemonResponse }
+  | DirectIosSelectorErrorResult
   | null;
 
 type ResolvedDirectIosSelectorQuery =
@@ -91,7 +93,7 @@ type ResolvedDirectIosSelectorQuery =
       selector: DirectIosSelectorTarget;
       result: DirectIosSelectorQueryResult;
     }
-  | { kind: 'error'; response: DaemonResponse }
+  | DirectIosSelectorErrorResult
   | null;
 
 export async function dispatchFindReadOnlyViaRuntime(
@@ -419,7 +421,7 @@ async function queryDirectIosSelectorOrFallback(
 
 function isDirectIosSelectorErrorResult(
   result: DirectIosSelectorFallbackResult | ResolvedDirectIosSelectorQuery,
-): result is { kind: 'error'; response: DaemonResponse } {
+): result is DirectIosSelectorErrorResult {
   return result !== null && 'kind' in result && result.kind === 'error';
 }
 
diff --git a/src/daemon/types.ts b/src/daemon/types.ts
index 49a2924e4..18fe3ed3a 100644
--- a/src/daemon/types.ts
+++ b/src/daemon/types.ts
@@ -12,7 +12,7 @@ import type {
 export type { DaemonLockPolicy } from '../contracts.ts';
 import type { CommandFlags } from '../core/dispatch.ts';
 import type { GestureReferenceFrame, ScrollDirection } from '../core/scroll-gesture.ts';
-import type { NetworkLogBackend } from './network-log.ts';
+import type { LogBackend } from './network-log.ts';
 import type { SessionSurface } from '../core/session-surface.ts';
 import type { DeviceInfo, Platform, PlatformSelector } from '../utils/device.ts';
 import type { ExecBackgroundResult, ExecResult } from '../utils/exec.ts';
@@ -265,7 +265,7 @@ export type SessionState = {
   /** Session-scoped app log stream; logs written to outPath for agent to grep */
   appLog?: {
     platform: Platform;
-    backend: NetworkLogBackend;
+    backend: LogBackend;
     outPath: string;
     startedAt: number;
     getState: () => AppLogState;
diff --git a/src/mcp/command-tools.ts b/src/mcp/command-tools.ts
index a89a13077..95367d27d 100644
--- a/src/mcp/command-tools.ts
+++ b/src/mcp/command-tools.ts
@@ -6,7 +6,7 @@ import {
   type CommandName,
 } from '../commands/command-metadata.ts';
 
-type ToolResult = {
+export type ToolResult = {
   isError: boolean;
   structuredContent?: unknown;
   content: Array<{ type: 'text'; text: string }>;
diff --git a/src/mcp/router.ts b/src/mcp/router.ts
index db4f51ed0..a3684e12f 100644
--- a/src/mcp/router.ts
+++ b/src/mcp/router.ts
@@ -1,4 +1,4 @@
-import { listCommandTools, commandToolExecutor } from './command-tools.ts';
+import { listCommandTools, commandToolExecutor, type ToolResult } from './command-tools.ts';
 import { readVersion } from '../utils/version.ts';
 import type { JsonRpcId, JsonRpcRequestEnvelope } from '../contracts.ts';
 
@@ -56,7 +56,7 @@ async function handleRequest(method: string, params: unknown): Promise<unknown>
   }
 }
 
-async function callTool(params: unknown): Promise<unknown> {
+async function callTool(params: unknown): Promise<ToolResult> {
   const record = asRecord(params);
   const name = stringField(record, 'name');
   try {
@@ -70,7 +70,7 @@ function supportedProtocolVersion(_params: unknown): string {
   return SUPPORTED_PROTOCOL_VERSION;
 }
 
-function textToolResult(text: string, isError = false): unknown {
+function textToolResult(text: string, isError = false): ToolResult {
   return {
     isError,
     content: [{ type: 'text', text }],
diff --git a/src/platforms/ios/interactions.ts b/src/platforms/ios/interactions.ts
index cf240704d..aff2834e1 100644
--- a/src/platforms/ios/interactions.ts
+++ b/src/platforms/ios/interactions.ts
@@ -3,17 +3,17 @@ import type { DeviceInfo } from '../../utils/device.ts';
 import { buildScrollGesturePlan, type ScrollDirection } from '../../core/scroll-gesture.ts';
 import { runIosRunnerCommand } from './runner-client.ts';
 import type { RunnerCommand } from './runner-contract.ts';
-import type { BackMode, Interactor, RunnerContext } from '../../core/interactor-types.ts';
+import type {
+  BackMode,
+  Interactor,
+  RunnerCallOptions,
+  RunnerContext,
+} from '../../core/interactor-types.ts';
 
 export type AppleBackRunnerCommand = 'backInApp' | 'backSystem';
 type AppleRemoteButton = NonNullable<RunnerCommand['remoteButton']>;
 type RunIosRunnerCommand = typeof runIosRunnerCommand;
-type RunnerOpts = {
-  verbose?: boolean;
-  logPath?: string;
-  traceLogPath?: string;
-  requestId?: string;
-};
+type RunnerOpts = RunnerCallOptions;
 
 type InteractionFrame = {
   originX: number;
diff --git a/src/platforms/ios/runner-provider.ts b/src/platforms/ios/runner-provider.ts
index b06c55e55..d8a7b42c4 100644
--- a/src/platforms/ios/runner-provider.ts
+++ b/src/platforms/ios/runner-provider.ts
@@ -1,6 +1,7 @@
 import { AsyncLocalStorage } from 'node:async_hooks';
 import type { DeviceInfo } from '../../utils/device.ts';
 import type { RunnerCommand } from './runner-contract.ts';
+import type { RunnerXctestrunArtifactState, RunnerXctestrunCacheKind } from './runner-xctestrun.ts';
 
 export type AppleRunnerCommandOptions = {
   verbose?: boolean;
@@ -12,7 +13,6 @@ export type AppleRunnerCommandOptions = {
 };
 
 export type AppleRunnerLifecycleOptions = AppleRunnerCommandOptions & {
-  cleanStaleBundles?: boolean;
   buildTimeoutMs?: number;
   forceRunnerXctestrunRebuild?: boolean;
 };
@@ -25,8 +25,8 @@ export type AppleRunnerPrepareOptions = AppleRunnerLifecycleOptions & {
 
 export type AppleRunnerPrepareResult = {
   runner: Record<string, unknown>;
-  cache?: 'exact' | 'restore-key' | 'miss';
-  artifact?: 'valid' | 'rebuilt';
+  cache?: RunnerXctestrunCacheKind;
+  artifact?: RunnerXctestrunArtifactState;
   buildMs?: number;
   connectMs: number;
   healthCheckMs: number;
diff --git a/src/platforms/ios/runner-xctestrun.ts b/src/platforms/ios/runner-xctestrun.ts
index acfe19d16..111df89f9 100644
--- a/src/platforms/ios/runner-xctestrun.ts
+++ b/src/platforms/ios/runner-xctestrun.ts
@@ -110,11 +110,14 @@ export type RunnerXctestrunCacheMetadata = {
   artifacts?: RunnerXctestrunCacheArtifacts;
 };
 
+export type RunnerXctestrunCacheKind = 'exact' | 'restore-key' | 'miss';
+export type RunnerXctestrunArtifactState = 'valid' | 'rebuilt';
+
 export type RunnerXctestrunArtifact = {
   xctestrunPath: string;
   derived: string;
-  cache: 'exact' | 'restore-key' | 'miss';
-  artifact: 'valid' | 'rebuilt';
+  cache: RunnerXctestrunCacheKind;
+  artifact: RunnerXctestrunArtifactState;
   buildMs: number;
   xctestrunPathSource: 'manifest' | 'scan' | 'build';
   reason?: string;
diff --git a/src/utils/string-enum.ts b/src/utils/string-enum.ts
new file mode 100644
index 000000000..3c51fdaba
--- /dev/null
+++ b/src/utils/string-enum.ts
@@ -0,0 +1,35 @@
+import { AppError } from './errors.ts';
+
+/**
+ * Membership guard for an `as const` string tuple (the single source of truth for
+ * a string-literal union). Narrows `value` to the tuple's element union.
+ */
+export function isStringMember<const T extends readonly string[]>(
+  values: T,
+  value: string,
+): value is T[number] {
+  return values.includes(value);
+}
+
+/**
+ * Strict (exact-match) parse for an `as const` string tuple. Throws an
+ * `INVALID_ARGS` AppError when `value` is not a member. Pass `normalize` to
+ * trim/lowercase before matching, and `message` for a custom error.
+ *
+ * Note: only for strict vocabularies — parsers that accept aliases (e.g.
+ * device rotation `left` -> `landscape-left`) keep their own logic.
+ */
+export function parseStringMember<const T extends readonly string[]>(
+  values: T,
+  value: string | undefined,
+  options: { normalize?: (raw: string) => string; message?: string } = {},
+): T[number] {
+  const normalized = value === undefined ? undefined : (options.normalize?.(value) ?? value);
+  if (normalized !== undefined && isStringMember(values, normalized)) {
+    return normalized;
+  }
+  throw new AppError(
+    'INVALID_ARGS',
+    options.message ?? `Invalid value: ${value}. Use ${values.join('|')}.`,
+  );
+}