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skills/xstate-audition/references/core-functions.md

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+# xstate-audition Core Functions API Reference
+
+Complete API reference for all xstate-audition testing functions.
+
+## Function Naming Conventions
+
+All functions follow consistent naming patterns:
+
+- **`runUntil*()`**: Starts actor, waits for condition, **stops** actor
+- **`waitFor*()`**: Starts actor, waits for condition, **keeps** actor running
+- **`*With()`**: Accepts `AuditionOptions` as second parameter
+- **Without `With()`**: Uses default options (no `AuditionOptions` parameter)
+
+## runUntilDone / waitForDone
+
+Run a Promise Actor or State Machine Actor to completion.
+
+### Signatures
+
+```typescript
+function runUntilDone<TLogic extends AnyActorLogic>(
+  actor: Actor<TLogic>,
+): Promise<OutputFrom<TLogic>>;
+
+function runUntilDoneWith<TLogic extends AnyActorLogic>(
+  actor: Actor<TLogic>,
+  options: AuditionOptions,
+): Promise<OutputFrom<TLogic>>;
+```
+
+### Parameters
+
+- **`actor`**: Actor to run (Promise Actor or State Machine Actor)
+- **`options`** (With variant only): `AuditionOptions` object
+
+### Returns
+
+`Promise<Output>` - Resolves with actor output when reaching final state
+
+### Behavior
+
+- Starts the actor if not already started
+- Waits for actor to reach final state (`type: 'final'`)
+- Immediately stops the actor upon completion
+- Rejects if timeout expires before completion
+
+### Example
+
+```typescript
+const promiseLogic = fromPromise<string>(async () => 'result');
+const actor = createActor(promiseLogic);
+
+const output = await runUntilDone(actor);
+// output === 'result'
+
+// With timeout
+await runUntilDoneWith(actor, { timeout: 100 });
+```
+
+### Notes
+
+- Similar to XState's `toPromise()` but with options support
+- No `waitForDone()` variant (would be identical to `runUntilDone()`)
+
+---
+
+## runUntilEmitted / waitForEmitted
+
+Run a State Machine until it emits specified events.
+
+### Signatures
+
+```typescript
+function runUntilEmitted<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  emittedTypes: Array<EmittedFrom<TActor>['type']>,
+): Promise<Array<EmittedFrom<TActor>>>;
+
+function runUntilEmittedWith<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  options: AuditionOptions,
+  emittedTypes: Array<EmittedFrom<TActor>['type']>,
+): Promise<Array<EmittedFrom<TActor>>>;
+
+function waitForEmitted<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  emittedTypes: Array<EmittedFrom<TActor>['type']>,
+): Promise<Array<EmittedFrom<TActor>>>;
+
+function waitForEmittedWith<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  options: AuditionOptions,
+  emittedTypes: Array<EmittedFrom<TActor>['type']>,
+): Promise<Array<EmittedFrom<TActor>>>;
+```
+
+### Parameters
+
+- **`actor`**: State Machine Actor
+- **`options`** (With variant only): `AuditionOptions` object
+- **`emittedTypes`**: Array of event type strings to wait for
+
+### Returns
+
+`Promise<Event[]>` - Resolves with array of emitted events (in order emitted)
+
+### Behavior
+
+- Starts the actor if not already started
+- Waits for all specified event types to be emitted (via `emit()` action)
+- `runUntil*` stops actor after all events emitted
+- `waitFor*` keeps actor running after events emitted
+- Order of events in array matches emission order
+
+### Example
+
+```typescript
+const machine = setup({
+  types: {
+    emitted: {} as { type: 'READY' } | { type: 'DONE'; value: string },
+  },
+}).createMachine({
+  entry: [emit({ type: 'READY' }), emit({ type: 'DONE', value: 'success' })],
+});
+
+const actor = createActor(machine);
+const [readyEvent, doneEvent] = await runUntilEmitted(actor, ['READY', 'DONE']);
+// readyEvent.type === 'READY'
+// doneEvent.type === 'DONE', doneEvent.value === 'success'
+```
+
+### Notes
+
+- Only applies to events emitted via XState's event emitter API (`emit()`)
+- Does NOT track events sent between actors (use `runUntilEventSent/Received`)
+- Events must be emitted in any order, not necessarily the specified order
+
+### Currying
+
+```typescript
+// Curry with actor
+const runUntilEmit = runUntilEmitted(actor);
+const events = await runUntilEmit(['READY', 'DONE']);
+```
+
+---
+
+## runUntilTransition / waitForTransition
+
+Run a State Machine until it transitions from one state to another.
+
+### Signatures
+
+```typescript
+function runUntilTransition<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  fromStateId: string,
+  toStateId: string,
+): Promise<void>;
+
+function runUntilTransitionWith<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  options: AuditionOptions,
+  fromStateId: string,
+  toStateId: string,
+): Promise<void>;
+
+function waitForTransition<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  fromStateId: string,
+  toStateId: string,
+): Promise<void>;
+
+function waitForTransitionWith<TActor extends AnyStateMachineActor>(
+  actor: TActor,
+  options: AuditionOptions,
+  fromStateId: string,
+  toStateId: string,
+): Promise<void>;
+```
+
+### Parameters
+
+- **`actor`**: State Machine Actor
+- **`options`** (With variant only): `AuditionOptions` object
+- **`fromStateId`**: Full state ID (including machine ID prefix)
+- **`toStateId`**: Full state ID (including machine ID prefix)
+
+### Returns
+
+`Promise<void>` - Resolves when transition occurs
+
+### Behavior
+
+- Starts the actor if not already started
+- Waits for actor to be in state `fromStateId`
+- Then waits for transition to state `toStateId`
+- `runUntil*` stops actor after transition
+- `waitFor*` keeps actor running after transition
+- Rejects if transition doesn't occur within timeout
+
+### Example
+
+```typescript
+const machine = createMachine({
+  id: 'fetch',
+  initial: 'idle',
+  states: {
+    idle: {
+      on: { FETCH: 'loading' },
+    },
+    loading: {
+      on: { SUCCESS: 'success' },
+    },
+    success: {},
+  },
+});
+
+const actor = createActor(machine);
+
+// Setup promise
+const promise = runUntilTransition(actor, 'fetch.idle', 'fetch.loading');
+
+// Send event
+actor.send({ type: 'FETCH' });
+
+// Wait for transition
+await promise;
+```
+
+### Important Notes
+
+- **State IDs must include machine ID prefix**: `'machineId.stateId'`
+- If no machine ID provided in `createMachine()`, default is `'(machine)'`
+- Transition must be direct (from → to), not via intermediate states
+- Useful for testing explicit transition paths
+
+### Currying
+
+```typescript
+// Curry with actor and fromState
+const runFromIdle = runUntilTransition(actor, 'fetch.idle');
+await runFromIdle('fetch.loading');
+```
+
+---
+
+## runUntilSnapshot / waitForSnapshot
+
+Run an Actor until its snapshot satisfies a predicate.
+
+### Signatures
+
+```typescript
+function runUntilSnapshot<TActor extends AnyActor>(
+  actor: TActor,
+  predicate: (snapshot: SnapshotFrom<TActor>) => boolean,
+): Promise<SnapshotFrom<TActor>>;
+
+function runUntilSnapshotWith<TActor extends AnyActor>(
+  actor: TActor,
+  options: AuditionOptions,
+  predicate: (snapshot: SnapshotFrom<TActor>) => boolean,
+): Promise<SnapshotFrom<TActor>>;
+
+function waitForSnapshot<TActor extends AnyActor>(
+  actor: TActor,
+  predicate: (snapshot: SnapshotFrom<TActor>) => boolean,
+): Promise<SnapshotFrom<TActor>>;
+
+function waitForSnapshotWith<TActor extends AnyActor>(
+  actor: TActor,
+  options: AuditionOptions,
+  predicate: (snapshot: SnapshotFrom<TActor>) => boolean,
+): Promise<SnapshotFrom<TActor>>;
+```
+
+### Parameters
+
+- **`actor`**: Any Actor type
+- **`options`** (With variant only): `AuditionOptions` object
+- **`predicate`**: Function that tests snapshot conditions
+
+### Returns
+
+`Promise<Snapshot>` - Resolves with snapshot that satisfied predicate
+
+### Behavior
+
+- Starts the actor if not already started
+- Evaluates predicate on each snapshot change
+- Resolves when predicate returns `true`
+- `runUntil*` stops actor after predicate satisfied
+- `waitFor*` keeps actor running after predicate satisfied
+
+### Example
+
+```typescript
+const machine = setup({
+  types: {
+    context: {} as { count: number; status: string },
+  },
+}).createMachine({
+  context: { count: 0, status: 'idle' },
+  on: {
+    INCREMENT: {
+      actions: assign({ count: ({ context }) => context.count + 1 }),
+    },
+  },
+});
+
+const actor = createActor(machine);
+
+const promise = runUntilSnapshot(
+  actor,
+  (snapshot) => snapshot.context.count >= 3,
+);
+
+actor.send({ type: 'INCREMENT' });
+actor.send({ type: 'INCREMENT' });
+actor.send({ type: 'INCREMENT' });
+
+const snapshot = await promise;
+// snapshot.context.count === 3
+```
+
+### Use Cases
+
+- Testing complex context conditions
+- Waiting for computed values
+- Combining multiple state/context checks
+- Testing conditions not tied to specific states
+
+### Notes
+
+- Similar to XState's `waitFor()` but with stop behavior
+- Predicate called on every snapshot change
+- Keep predicates performant (called frequently)
+
+---
+
+## runUntilSpawn / waitForSpawn
+
+Run a State Machine until it spawns a child actor.
+
+### Signatures
+
+```typescript
+function runUntilSpawn<TLogic extends AnyActorLogic = AnyActorLogic>(
+  actor: AnyStateMachineActor,
+  childId: string | RegExp,
+): Promise<ActorRefFrom<TLogic>>;
+
+function runUntilSpawnWith<TLogic extends AnyActorLogic = AnyActorLogic>(
+  actor: AnyStateMachineActor,
+  options: AuditionOptions,
+  childId: string | RegExp,
+): Promise<ActorRefFrom<TLogic>>;
+
+function waitForSpawn<TLogic extends AnyActorLogic = AnyActorLogic>(
+  actor: AnyStateMachineActor,
+  childId: string | RegExp,
+): Promise<ActorRefFrom<TLogic>>;
+
+function waitForSpawnWith<TLogic extends AnyActorLogic = AnyActorLogic>(
+  actor: AnyStateMachineActor,
+  options: AuditionOptions,
+  childId: string | RegExp,
+): Promise<ActorRefFrom<TLogic>>;
+```
+
+### Parameters
+
+- **`actor`**: State Machine Actor (parent)
+- **`options`** (With variant only): `AuditionOptions` object
+- **`childId`**: String or RegExp to match spawned child ID
+
+### Type Parameters
+
+- **`TLogic`**: Type of the spawned child's logic (for type safety)
+
+### Returns
+
+`Promise<ActorRef>` - Resolves with reference to spawned child actor
+
+### Behavior
+
+- Starts the actor if not already started
+- Waits for any actor in the system to spawn child with matching ID
+- `runUntil*` stops parent actor after spawn detected
+- `waitFor*` keeps parent actor running after spawn detected
+- Can match child spawned by parent or any descendant
+
+### Example
+
+```typescript
+const childLogic = fromPromise<string>(async () => 'child result');
+
+const parentMachine = setup({
+  actors: { child: childLogic },
+}).createMachine({
+  on: {
+    SPAWN: {
+      actions: spawnChild('child', { id: 'myChild' }),
+    },
+  },
+});
+
+const actor = createActor(parentMachine);
+
+// Provide explicit type for child
+const promise = waitForSpawn<typeof childLogic>(actor, 'myChild');
+
+actor.send({ type: 'SPAWN' });
+
+const childRef = await promise;
+// childRef.id === 'myChild'
+// childRef has correct typing based on childLogic
+```
+
+### Important Notes
+
+- **Always provide type parameter** for proper TypeScript typing
+- Without type parameter, returns `AnyActorRef` (not useful)
+- Cannot specify which parent should spawn the child
+- Useful for testing actor hierarchies and dynamic spawning
+
+### Currying
+
+```typescript
+const waitForChild = waitForSpawn<typeof childLogic>(actor);
+const childRef = await waitForChild('myChild');
+```
+
+---
+
+## runUntilEventReceived / waitForEventReceived
+
+Run an Actor until it receives specified events.
+
+### Signatures
+
+```typescript
+function runUntilEventReceived<TActor extends EventReceivingActor>(
+  actor: TActor,
+  eventTypes: Array<EventReceivedFrom<TActor>['type']>,
+): Promise<Array<EventReceivedFrom<TActor>>>;
+
+function runUntilEventReceivedWith<TActor extends EventReceivingActor>(
+  actor: TActor,
+  options: AuditionOptions & { otherActorId?: string | RegExp },
+  eventTypes: Array<EventReceivedFrom<TActor>['type']>,
+): Promise<Array<EventReceivedFrom<TActor>>>;
+
+function waitForEventReceived<TActor extends EventReceivingActor>(
+  actor: TActor,
+  eventTypes: Array<EventReceivedFrom<TActor>['type']>,
+): Promise<Array<EventReceivedFrom<TActor>>>;
+
+function waitForEventReceivedWith<TActor extends EventReceivingActor>(
+  actor: TActor,
+  options: AuditionOptions & { otherActorId?: string | RegExp },
+  eventTypes: Array<EventReceivedFrom<TActor>['type']>,
+): Promise<Array<EventReceivedFrom<TActor>>>;
+```
+
+### Parameters
+
+- **`actor`**: State Machine, Callback, or Transition Actor
+- **`options`** (With variant only): `AuditionOptions` with optional `otherActorId`
+- **`eventTypes`**: Array of event type strings to wait for
+
+### Options Extension
+
+- **`otherActorId`**: Filter events to only those received FROM actor with this ID
+
+### Returns
+
+`Promise<Event[]>` - Resolves with array of received events
+
+### Behavior
+
+- Starts the actor if not already started
+- Waits for all specified event types to be received
+- `runUntil*` stops actor after all events received
+- `waitFor*` keeps actor running after events received
+- If `otherActorId` provided, only counts events from that sender
+
+### Example
+
+```typescript
+const machine = setup({
+  types: {
+    events: {} as { type: 'PING' } | { type: 'PONG' },
+  },
+}).createMachine({
+  on: {
+    PING: { actions: /* respond */ },
+    PONG: { actions: /* respond */ },
+  },
+});
+
+const actor = createActor(machine);
+const promise = runUntilEventReceived(actor, ['PING', 'PONG']);
+
+actor.send({ type: 'PING' });
+actor.send({ type: 'PONG' });
+
+const [pingEvent, pongEvent] = await promise;
+```
+
+### Use Cases
+
+- Testing event handling
+- Verifying inter-actor communication
+- Testing event sources and filters
+
+---
+
+## runUntilEventSent / waitForEventSent
+
+Run an Actor until it sends specified events to other actors.
+
+### Signatures
+
+```typescript
+function runUntilEventSent<TActor extends AnyActor>(
+  actor: TActor,
+  eventTypes: string[],
+): Promise<Array<EventObject>>;
+
+function runUntilEventSentWith<TActor extends AnyActor>(
+  actor: TActor,
+  options: AuditionOptions & { otherActorId?: string | RegExp },
+  eventTypes: string[],
+): Promise<Array<EventObject>>;
+
+function waitForEventSent<TActor extends AnyActor>(
+  actor: TActor,
+  eventTypes: string[],
+): Promise<Array<EventObject>>;
+
+function waitForEventSentWith<TActor extends AnyActor>(
+  actor: TActor,
+  options: AuditionOptions & { otherActorId?: string | RegExp },
+  eventTypes: string[],
+): Promise<Array<EventObject>>;
+```
+
+### Parameters
+
+- **`actor`**: Any Actor type
+- **`options`** (With variant only): `AuditionOptions` with optional `otherActorId`
+- **`eventTypes`**: Array of event type strings to wait for
+
+### Options Extension
+
+- **`otherActorId`**: Filter events to only those sent TO actor with this ID
+
+### Returns
+
+`Promise<Event[]>` - Resolves with array of sent events
+
+### Behavior
+
+- Starts the actor if not already started
+- Waits for actor to send all specified event types
+- `runUntil*` stops actor after all events sent
+- `waitFor*` keeps actor running after events sent
+- If `otherActorId` provided, only counts events to that recipient
+
+### Example
+
+```typescript
+const childLogic = fromPromise<string>(async () => 'done');
+
+const parentMachine = setup({
+  actors: { child: childLogic },
+}).createMachine({
+  invoke: {
+    id: 'child',
+    src: 'child',
+    onDone: {
+      actions: sendTo('child', { type: 'COMPLETE' }),
+    },
+  },
+});
+
+const actor = createActor(parentMachine);
+const [sentEvent] = await runUntilEventSent(actor, ['COMPLETE']);
+// sentEvent.type === 'COMPLETE'
+```
+
+---
+
+## createActorFromLogic
+
+Curried function to create actors from logic.
+
+### Signature
+
+```typescript
+function createActorFromLogic<TLogic extends AnyActorLogic>(
+  logic: TLogic,
+  options?: ActorOptions<TLogic>,
+): Actor<TLogic>;
+
+// Curried
+const createActor = createActorFromLogic(logic);
+const actor = createActor(options);
+```
+
+### Parameters
+
+- **`logic`**: Actor logic (machine, promise logic, etc.)
+- **`options`**: XState actor options (input, inspect, logger, etc.)
+
+### Returns
+
+Curried function or Actor
+
+### Use Case
+
+Reduce boilerplate when testing same logic with different inputs:
+
+```typescript
+const createActor = createActorFromLogic(myLogic);
+
+it('should work with input A', async () => {
+  const actor = createActor({ input: 'A' });
+  await runUntilDone(actor);
+});
+
+it('should work with input B', async () => {
+  const actor = createActor({ input: 'B' });
+  await runUntilDone(actor);
+});
+```
+
+---
+
+## createActorWith
+
+Curried function to create actors with options.
+
+### Signature
+
+```typescript
+function createActorWith<TLogic extends AnyActorLogic>(
+  options: ActorOptions<TLogic>,
+  logic: TLogic,
+): Actor<TLogic>;
+
+// Curried
+const createActor = createActorWith(options);
+const actor = createActor(logic);
+```
+
+### Parameters
+
+- **`options`**: XState actor options (input, inspect, logger, etc.)
+- **`logic`**: Actor logic (machine, promise logic, etc.)
+
+### Returns
+
+Curried function or Actor
+
+### Use Case
+
+Reduce boilerplate when testing different logic with same input:
+
+```typescript
+const createActor = createActorWith({ input: 'testInput' });
+
+it('should work with machineA', async () => {
+  const actor = createActor(machineA);
+  await runUntilDone(actor);
+});
+
+it('should work with machineB', async () => {
+  const actor = createActor(machineB);
+  await runUntilDone(actor);
+});
+```
+
+---
+
+## patchActor
+
+Modify an Actor for use with xstate-audition.
+
+### Signature
+
+```typescript
+function patchActor<TActor extends AnyActor>(
+  actor: TActor,
+  options?: AuditionOptions,
+): TActor;
+```
+
+### Parameters
+
+- **`actor`**: Actor to modify
+- **`options`**: Optional `AuditionOptions`
+
+### Returns
+
+Modified actor (same reference)
+
+### Notes
+
+- Used internally by all other functions
+- Mutates the actor (adds internal tracking)
+- Generally not needed in user code
+- All other xstate-audition functions call this automatically
+
+---
+
+## unpatchActor
+
+Revert modifications made by xstate-audition.
+
+### Signature
+
+```typescript
+function unpatchActor<TActor extends AnyActor>(actor: TActor): TActor;
+```
+
+### Parameters
+
+- **`actor`**: Actor to revert
+
+### Returns
+
+Reverted actor (same reference)
+
+### Notes
+
+- **Experimental** - may be removed in future
+- Undoes internal mutations from `patchActor()`
+- No-op if actor was never patched
+- Rarely needed in practice
+
+---
+
+## Quick Reference Table
+
+| Function                | Condition          | Stops Actor | Keeps Running | Options Support |
+| ----------------------- | ------------------ | ----------- | ------------- | --------------- |
+| `runUntilDone`          | Final state        | Yes         | No            | With variant    |
+| `runUntilEmitted`       | Events emitted     | Yes         | No            | With variant    |
+| `waitForEmitted`        | Events emitted     | No          | Yes           | With variant    |
+| `runUntilTransition`    | State transition   | Yes         | No            | With variant    |
+| `waitForTransition`     | State transition   | No          | Yes           | With variant    |
+| `runUntilSnapshot`      | Snapshot predicate | Yes         | No            | With variant    |
+| `waitForSnapshot`       | Snapshot predicate | No          | Yes           | With variant    |
+| `runUntilSpawn`         | Child spawned      | Yes         | No            | With variant    |
+| `waitForSpawn`          | Child spawned      | No          | Yes           | With variant    |
+| `runUntilEventReceived` | Events received    | Yes         | No            | With variant    |
+| `waitForEventReceived`  | Events received    | No          | Yes           | With variant    |
+| `runUntilEventSent`     | Events sent        | Yes         | No            | With variant    |
+| `waitForEventSent`      | Events sent        | No          | Yes           | With variant    |
+| `createActorFromLogic`  | N/A (utility)      | N/A         | N/A           | No              |
+| `createActorWith`       | N/A (utility)      | N/A         | N/A           | No              |
+| `patchActor`            | N/A (internal)     | N/A         | N/A           | Yes             |
+| `unpatchActor`          | N/A (internal)     | N/A         | N/A           | No              |

skills/xstate-audition/references/options-types.md

@@ -0,0 +1,545 @@
+# xstate-audition Options & Types Reference
+
+Complete reference for AuditionOptions and TypeScript types used throughout xstate-audition.
+
+## AuditionOptions
+
+Configuration object accepted by all functions ending in `With()`.
+
+### Type Definition
+
+```typescript
+interface AuditionOptions {
+  /**
+   * Inspector callback or observer to attach to actor Will not overwrite
+   * existing inspectors
+   */
+  inspector?: ((event: InspectionEvent) => void) | Observer<InspectionEvent>;
+
+  /**
+   * Custom logger function Default: no-op (no logging) XState default:
+   * console.log
+   */
+  logger?: (...args: any[]) => void;
+
+  /**
+   * Maximum milliseconds to wait for condition Default: 1000 Set to 0,
+   * negative, or Infinity to disable
+   */
+  timeout?: number;
+}
+```
+
+### Properties
+
+#### `inspector`
+
+**Type**: `((event: InspectionEvent) => void) | Observer<InspectionEvent>`
+**Default**: `undefined`
+**Optional**: Yes
+
+Attaches a custom inspector to the actor for debugging and monitoring.
+
+**Callback signature**:
+
+```typescript
+(event: InspectionEvent) => void;
+```
+
+**Observer signature**:
+
+```typescript
+interface Observer<T> {
+  next: (value: T) => void;
+  error?: (error: any) => void;
+  complete?: () => void;
+}
+```
+
+**Behavior**:
+
+- Merges with any existing inspectors (doesn't replace)
+- Called for every inspection event from the actor
+- Useful for debugging failed tests
+- Similar to `inspect` option in `createActor()`
+
+**Example**:
+
+```typescript
+await runUntilDoneWith(actor, {
+  inspector: (event) => {
+    console.log('Inspection event:', event.type);
+  },
+});
+
+// Or with observer
+await runUntilDoneWith(actor, {
+  inspector: {
+    next: (event) => console.log('Event:', event),
+    error: (err) => console.error('Error:', err),
+    complete: () => console.log('Complete'),
+  },
+});
+```
+
+**InspectionEvent types**:
+
+```typescript
+type InspectionEvent =
+  | { type: 'actor.snapshot'; actorRef: AnyActorRef; snapshot: Snapshot }
+  | { type: 'actor.event'; actorRef: AnyActorRef; event: EventObject }
+  | { type: 'actor.state'; actorRef: AnyActorRef; state: StateValue };
+// ... and more
+```
+
+---
+
+#### `logger`
+
+**Type**: `(...args: any[]) => void`
+**Default**: `() => {}` (no-op)
+**Optional**: Yes
+
+Sets a custom logger for the actor and all its children.
+
+**Behavior**:
+
+- Replaces actor's default logger
+- Cascades to all child actors
+- XState's default logger is `console.log`
+- xstate-audition's default is no-op (silent)
+- Useful for debugging test failures
+
+**Example**:
+
+```typescript
+await runUntilDoneWith(actor, {
+  logger: console.log, // Use console.log
+});
+
+await runUntilDoneWith(actor, {
+  logger: (...args) => {
+    // Custom formatting
+    console.log('[XState]', ...args);
+  },
+});
+
+// With test framework logger
+await runUntilDoneWith(actor, {
+  logger: vi.fn(), // Vitest mock
+});
+```
+
+**What gets logged**:
+
+- State transitions
+- Action executions
+- Event handling
+- Context updates
+- Guard evaluations
+
+---
+
+#### `timeout`
+
+**Type**: `number`
+**Default**: `1000` (milliseconds)
+**Optional**: Yes
+
+Maximum time to wait for condition before rejecting the promise.
+
+**Behavior**:
+
+- Measured in milliseconds
+- Default is 1000ms (1 second)
+- Set to `0`, negative number, or `Infinity` to disable timeout
+- Should be **less than your test framework's timeout**
+- Timeout error message includes elapsed time
+
+**Example**:
+
+```typescript
+// 5 second timeout
+await runUntilDoneWith(actor, { timeout: 5000 });
+
+// No timeout
+await runUntilDoneWith(actor, { timeout: 0 });
+await runUntilDoneWith(actor, { timeout: Infinity });
+
+// Will reject after 100ms
+await assert.rejects(
+  runUntilDoneWith(slowActor, { timeout: 100 }),
+  (err: Error) => {
+    assert.match(err.message, /did not complete in 100ms/);
+    return true;
+  },
+);
+```
+
+**Timeout error format**:
+
+```typescript
+// Error message pattern
+`Actor did not complete in ${timeout}ms`;
+`Actor did not emit [${types}] in ${timeout}ms`;
+`Actor did not transition from ${from} to ${to} in ${timeout}ms`;
+// etc.
+```
+
+**Best practices**:
+
+1. Set explicit timeouts for slow operations
+2. Keep timeout < test framework timeout
+3. Use longer timeouts in CI environments
+4. Disable timeout for debugging (set to `Infinity`)
+
+---
+
+### Extended Options
+
+Some functions accept additional options beyond `AuditionOptions`.
+
+#### Event Filtering Options
+
+Used by `runUntilEventReceivedWith` and `runUntilEventSentWith`:
+
+```typescript
+interface EventFilterOptions extends AuditionOptions {
+  /**
+   * Filter events by source/target actor ID String: exact match RegExp: pattern
+   * match
+   */
+  otherActorId?: string | RegExp;
+}
+```
+
+**Example**:
+
+```typescript
+// Only events received FROM actor with ID 'child'
+await runUntilEventReceivedWith(actor, { otherActorId: 'child' }, ['PING']);
+
+// Events from any actor matching pattern
+await runUntilEventReceivedWith(actor, { otherActorId: /^child-\d+$/ }, [
+  'PING',
+]);
+
+// Only events sent TO actor with ID 'parent'
+await runUntilEventSentWith(actor, { otherActorId: 'parent' }, ['RESPONSE']);
+```
+
+---
+
+## TypeScript Types
+
+### Curried Function Types
+
+xstate-audition exports types for curried function variants.
+
+#### Example: `CurryEmittedP1`
+
+Type for partially applied `runUntilEmitted()`:
+
+```typescript
+type CurryEmittedP1<TActor extends AnyStateMachineActor> = (
+  emittedTypes: Array<EmittedFrom<TActor>['type']>,
+) => Promise<Array<EmittedFrom<TActor>>>;
+
+// Usage
+let actor: Actor<typeof machine>;
+let runUntilEmit: CurryEmittedP1<typeof actor>;
+
+runUntilEmit = runUntilEmitted(actor);
+const events = await runUntilEmit(['EVENT1', 'EVENT2']);
+```
+
+#### Example: `CurryTransitionP2`
+
+Type for partially applied `runUntilTransition()`:
+
+```typescript
+type CurryTransitionP2<TActor extends AnyStateMachineActor> = (
+  toStateId: string,
+) => Promise<void>;
+
+// Usage
+let actor: Actor<typeof machine>;
+let runFromIdle: CurryTransitionP2<typeof actor>;
+
+runFromIdle = runUntilTransition(actor, 'machine.idle');
+await runFromIdle('machine.loading');
+```
+
+### Actor Type Constraints
+
+Types that constrain which actors can be used with specific functions.
+
+#### `AnyStateMachineActor`
+
+```typescript
+type AnyStateMachineActor = Actor<
+  StateMachine<any, any, any, any, any, any, any, any, any>
+>;
+```
+
+Used by: `runUntilEmitted`, `runUntilTransition`, `runUntilSpawn`
+
+#### `EventReceivingActor`
+
+```typescript
+type EventReceivingActor =
+  | AnyStateMachineActor
+  | CallbackActor
+  | TransitionActor;
+```
+
+Used by: `runUntilEventReceived`, `waitForEventReceived`
+
+#### `AnyActor`
+
+```typescript
+type AnyActor = Actor<AnyActorLogic>;
+```
+
+Used by: `runUntilSnapshot`, `runUntilEventSent`, and most other functions
+
+### Utility Types from XState
+
+xstate-audition leverages XState's utility types:
+
+#### `SnapshotFrom<TActor>`
+
+Extracts snapshot type from actor:
+
+```typescript
+import { SnapshotFrom } from 'xstate';
+
+const machine = createMachine({...});
+type MachineSnapshot = SnapshotFrom<typeof machine>;
+```
+
+#### `OutputFrom<TLogic>`
+
+Extracts output type from logic:
+
+```typescript
+import { OutputFrom } from 'xstate';
+
+const promiseLogic = fromPromise<string>(async () => 'result');
+type Output = OutputFrom<typeof promiseLogic>; // string
+```
+
+#### `EmittedFrom<TActor>`
+
+Extracts emitted event types from actor:
+
+```typescript
+import { EmittedFrom } from 'xstate';
+
+const machine = setup({
+  types: {
+    emitted: {} as { type: 'READY' } | { type: 'DONE' },
+  },
+}).createMachine({...});
+
+type Emitted = EmittedFrom<typeof machine>;
+// { type: 'READY' } | { type: 'DONE' }
+```
+
+#### `ActorRefFrom<TLogic>`
+
+Extracts actor reference type from logic:
+
+```typescript
+import { ActorRefFrom } from 'xstate';
+
+const childLogic = fromPromise<string>(async () => 'done');
+type ChildRef = ActorRefFrom<typeof childLogic>;
+
+const child = await runUntilSpawn<typeof childLogic>(parent, 'childId');
+// child has type ActorRefFrom<typeof childLogic>
+```
+
+---
+
+## Type Parameter Patterns
+
+### Providing Explicit Type Parameters
+
+Some functions benefit from explicit type parameters for better type inference.
+
+#### `runUntilSpawn` with Type Parameter
+
+**Why needed**: Child actor type cannot be inferred from ID alone
+
+```typescript
+// ❌ Without type parameter - returns AnyActorRef
+const child = await runUntilSpawn(parent, 'childId');
+// child: AnyActorRef (not useful)
+
+// ✅ With type parameter - returns properly typed ActorRef
+const childLogic = fromPromise<string>(async () => 'result');
+const child = await runUntilSpawn<typeof childLogic>(parent, 'childId');
+// child: ActorRefFrom<typeof childLogic>
+// child.getSnapshot() returns Promise<string>
+```
+
+#### Generic Actor Testing
+
+```typescript
+function testActor<TLogic extends AnyActorLogic>(
+  logic: TLogic,
+  input: InputFrom<TLogic>,
+) {
+  return async () => {
+    const actor = createActor(logic, { input });
+    const output = await runUntilDone(actor);
+    return output;
+  };
+}
+```
+
+---
+
+## Type Safety Best Practices
+
+### 1. Use `setup()` for Type Inference
+
+```typescript
+// ✅ Good - full type inference
+const machine = setup({
+  types: {
+    context: {} as { count: number },
+    events: {} as { type: 'INC' } | { type: 'DEC' },
+    emitted: {} as { type: 'CHANGED'; count: number },
+  },
+}).createMachine({...});
+
+// Now all xstate-audition functions have proper types
+const [event] = await runUntilEmitted(machine, ['CHANGED']);
+// event.type is 'CHANGED'
+// event.count is number
+```
+
+### 2. Explicitly Type Actors in Tests
+
+```typescript
+// ✅ Good - explicit typing
+let actor: Actor<typeof machine>;
+
+beforeEach(() => {
+  actor = createActor(machine);
+});
+
+// Now all uses of actor have correct type
+```
+
+### 3. Use Curried Types
+
+```typescript
+// ✅ Good - type curried functions
+let runFromIdle: CurryTransitionP2<typeof actor>;
+
+beforeEach(() => {
+  actor = createActor(machine);
+  runFromIdle = runUntilTransition(actor, 'machine.idle');
+});
+```
+
+---
+
+## Common Type Errors and Solutions
+
+### Error: "Type 'string' is not assignable to type 'never'"
+
+**Cause**: Event or emitted types not properly defined
+
+**Solution**:
+
+```typescript
+// ❌ Wrong - no types defined
+const machine = createMachine({...});
+
+// ✅ Fixed - define types with setup()
+const machine = setup({
+  types: {
+    events: {} as { type: 'FETCH' } | { type: 'SUCCESS' },
+  },
+}).createMachine({...});
+```
+
+### Error: "Property 'X' does not exist on type 'AnyActorRef'"
+
+**Cause**: Missing type parameter on `runUntilSpawn`
+
+**Solution**:
+
+```typescript
+// ❌ Wrong - no type parameter
+const child = await runUntilSpawn(parent, 'childId');
+
+// ✅ Fixed - provide type parameter
+const child = await runUntilSpawn<typeof childLogic>(parent, 'childId');
+```
+
+### Error: "Argument of type 'Promise<...>' is not assignable"
+
+**Cause**: Forgetting to `await` the promise
+
+**Solution**:
+
+```typescript
+// ❌ Wrong - not awaiting
+const result = runUntilDone(actor);
+
+// ✅ Fixed - await the promise
+const result = await runUntilDone(actor);
+```
+
+---
+
+## Configuration Defaults
+
+Quick reference for all default values:
+
+| Option         | Default Value           | Type                   |
+| -------------- | ----------------------- | ---------------------- |
+| `timeout`      | `1000` (ms)             | `number`               |
+| `logger`       | `() => {}` (no-op)      | `Function`             |
+| `inspector`    | `undefined` (none)      | `Function \| Observer` |
+| `otherActorId` | `undefined` (any actor) | `string \| RegExp`     |
+
+---
+
+## Creating Custom Wrappers
+
+You can create your own wrappers with preset options:
+
+```typescript
+import { runUntilDoneWith, AuditionOptions } from 'xstate-audition';
+
+// Custom wrapper with defaults
+function runWithDefaults<TLogic extends AnyActorLogic>(
+  actor: Actor<TLogic>,
+  overrides?: Partial<AuditionOptions>,
+) {
+  const options: AuditionOptions = {
+    timeout: 5000, // 5 seconds default
+    logger: console.log, // Always log
+    ...overrides,
+  };
+
+  return runUntilDoneWith(actor, options);
+}
+
+// Usage
+await runWithDefaults(actor); // Uses 5s timeout + console.log
+await runWithDefaults(actor, { timeout: 10000 }); // Override timeout
+```
+
+---
+
+## See Also
+
+- [Core Functions Reference](./core-functions.md) - Detailed API for all functions
+- [Testing Patterns](./testing-patterns.md) - Advanced usage patterns and examples

skills/xstate-audition/references/testing-patterns.md

@@ -0,0 +1,826 @@
+# xstate-audition Testing Patterns
+
+Advanced patterns, best practices, and real-world examples for testing XState actors with xstate-audition.
+
+## Table of Contents
+
+- [Test Organization Patterns](#test-organization-patterns)
+- [Currying Patterns](#currying-patterns)
+- [Hierarchical Actor Testing](#hierarchical-actor-testing)
+- [Event Communication Patterns](#event-communication-patterns)
+- [Timeout and Error Testing](#timeout-and-error-testing)
+- [Integration Testing Patterns](#integration-testing-patterns)
+- [Debugging Failed Tests](#debugging-failed-tests)
+- [Performance Testing](#performance-testing)
+- [Advanced TypeScript Patterns](#advanced-typescript-patterns)
+
+---
+
+## Test Organization Patterns
+
+### Pattern: Describe Block with Shared Setup
+
+Organize tests with shared actor creation and curried functions.
+
+```typescript
+import { describe, it, beforeEach } from 'node:test';
+import { strict as assert } from 'node:assert';
+import { createActor } from 'xstate';
+import {
+  runUntilDone,
+  runUntilTransition,
+  type CurryTransitionP2,
+} from 'xstate-audition';
+
+describe('FetchMachine', () => {
+  let actor: Actor<typeof fetchMachine>;
+  let runFromIdle: CurryTransitionP2<typeof actor>;
+
+  beforeEach(() => {
+    actor = createActor(fetchMachine);
+    runFromIdle = runUntilTransition(actor, 'fetch.idle');
+  });
+
+  describe('successful fetch', () => {
+    it('should transition from idle to loading', async () => {
+      actor.send({ type: 'FETCH' });
+      await runFromIdle('fetch.loading');
+    });
+
+    it('should complete with data', async () => {
+      actor.send({ type: 'FETCH' });
+      actor.send({ type: 'SUCCESS', data: 'test' });
+
+      const snapshot = await runUntilSnapshot(actor, (s) =>
+        s.matches('success'),
+      );
+
+      assert.equal(snapshot.context.data, 'test');
+    });
+  });
+
+  describe('failed fetch', () => {
+    it('should transition to error state', async () => {
+      actor.send({ type: 'FETCH' });
+      actor.send({ type: 'ERROR', error: new Error('Network error') });
+
+      await runFromIdle('fetch.error');
+    });
+  });
+});
+```
+
+### Pattern: Factory Functions for Test Actors
+
+Create reusable factory functions for common test scenarios.
+
+```typescript
+import { createActorFromLogic } from 'xstate-audition';
+
+// Factory with preset configuration
+function createTestActor(input: string) {
+  return createActor(myMachine, {
+    input,
+    logger: process.env.DEBUG ? console.log : undefined,
+  });
+}
+
+// Factory with currying
+const createActorWithInput = createActorFromLogic(myMachine);
+
+describe('myMachine', () => {
+  it('should work with input A', async () => {
+    const actor = createActorWithInput({ input: 'A' });
+    const output = await runUntilDone(actor);
+    assert.equal(output, 'processed-A');
+  });
+
+  it('should work with input B', async () => {
+    const actor = createActorWithInput({ input: 'B' });
+    const output = await runUntilDone(actor);
+    assert.equal(output, 'processed-B');
+  });
+});
+```
+
+### Pattern: Parameterized Tests
+
+Test multiple scenarios with the same logic.
+
+```typescript
+const testCases = [
+  { input: 'hello', expected: 'HELLO' },
+  { input: 'world', expected: 'WORLD' },
+  { input: '', expected: '' },
+];
+
+describe('StringTransformMachine', () => {
+  testCases.forEach(({ input, expected }) => {
+    it(`should transform "${input}" to "${expected}"`, async () => {
+      const actor = createActor(transformMachine, { input });
+      const output = await runUntilDone(actor);
+      assert.equal(output, expected);
+    });
+  });
+});
+```
+
+---
+
+## Currying Patterns
+
+### Pattern: Multi-Level Currying
+
+Create increasingly specific test helpers through currying.
+
+```typescript
+describe('TransitionMachine', () => {
+  let actor: Actor<typeof machine>;
+  let runWithActor: ReturnType<typeof runUntilTransition>;
+  let runFromIdle: CurryTransitionP2<typeof actor>;
+
+  beforeEach(() => {
+    actor = createActor(machine);
+
+    // Level 1: Curry with actor
+    runWithActor = runUntilTransition(actor);
+
+    // Level 2: Curry with actor + fromState
+    runFromIdle = runWithActor('machine.idle');
+  });
+
+  it('should transition to loading', async () => {
+    actor.send({ type: 'LOAD' });
+    // Level 3: Only provide toState
+    await runFromIdle('machine.loading');
+  });
+
+  it('should transition to success', async () => {
+    actor.send({ type: 'LOAD' });
+    actor.send({ type: 'SUCCESS' });
+    await runFromIdle('machine.success');
+  });
+});
+```
+
+### Pattern: Shared Options with Currying
+
+Create curried functions with preset options.
+
+```typescript
+import { runUntilSnapshotWith } from 'xstate-audition';
+
+describe('SlowMachine', () => {
+  const options = {
+    timeout: 5000,
+    logger: console.log,
+  };
+
+  it('should eventually reach done state', async () => {
+    const actor = createActor(slowMachine);
+
+    const snapshot = await runUntilSnapshotWith(actor, options, (s) =>
+      s.matches('done'),
+    );
+
+    assert.ok(snapshot.matches('done'));
+  });
+});
+```
+
+---
+
+## Hierarchical Actor Testing
+
+### Pattern: Parent-Child Communication
+
+Test parent-child actor interactions.
+
+```typescript
+import { waitForSpawn, waitForSnapshot } from 'xstate-audition';
+
+const childLogic = fromPromise<string, string>(async ({ input }) => {
+  return `processed: ${input}`;
+});
+
+const parentMachine = setup({
+  actors: { child: childLogic },
+  types: {
+    context: {} as { result?: string },
+    events: {} as { type: 'START'; value: string },
+  },
+}).createMachine({
+  initial: 'idle',
+  context: { result: undefined },
+  states: {
+    idle: {
+      on: {
+        START: 'processing',
+      },
+    },
+    processing: {
+      invoke: {
+        id: 'worker',
+        src: 'child',
+        input: ({ event }) => event.value,
+        onDone: {
+          target: 'done',
+          actions: assign({
+            result: ({ event }) => event.output,
+          }),
+        },
+      },
+    },
+    done: {
+      type: 'final',
+    },
+  },
+});
+
+describe('Parent-Child Communication', () => {
+  it('should spawn child and receive result', async () => {
+    const parent = createActor(parentMachine);
+
+    // Setup spawn detection
+    const childPromise = waitForSpawn<typeof childLogic>(parent, 'worker');
+
+    // Trigger spawning
+    parent.send({ type: 'START', value: 'test' });
+
+    // Wait for child to spawn
+    const child = await childPromise;
+    assert.equal(child.id, 'worker');
+
+    // Wait for parent to complete
+    const snapshot = await waitForSnapshot(parent, (s) => s.matches('done'));
+    assert.equal(snapshot.context.result, 'processed: test');
+
+    // Cleanup
+    parent.stop();
+  });
+});
+```
+
+### Pattern: Testing Actor Hierarchies
+
+Test complex multi-level actor systems.
+
+```typescript
+describe('Three-Level Hierarchy', () => {
+  it('should coordinate grandparent-parent-child', async () => {
+    const grandparent = createActor(grandparentMachine);
+
+    // Wait for parent to spawn
+    const parent = await waitForSpawn<typeof parentLogic>(
+      grandparent,
+      'parentActor',
+    );
+
+    // Wait for child to spawn (spawned by parent)
+    const child = await waitForSpawn<typeof childLogic>(
+      grandparent, // Detectable from root
+      'childActor',
+    );
+
+    // Send event to child
+    child.send({ type: 'WORK', value: 42 });
+
+    // Wait for result to propagate to grandparent
+    const snapshot = await waitForSnapshot(
+      grandparent,
+      (s) => s.context.finalResult !== undefined,
+    );
+
+    assert.equal(snapshot.context.finalResult, 42);
+
+    grandparent.stop();
+  });
+});
+```
+
+---
+
+## Event Communication Patterns
+
+### Pattern: Inter-Actor Event Flow
+
+Test event communication between actors.
+
+```typescript
+describe('Ping-Pong Actors', () => {
+  it('should exchange events', async () => {
+    const ping = createActor(pingMachine);
+    const pong = createActor(pongMachine);
+
+    // Start both actors
+    ping.start();
+    pong.start();
+
+    try {
+      // Setup detection for pong receiving PING
+      const pongPromise = waitForEventReceived(pong, ['PING']);
+
+      // Send PING from ping to pong
+      ping.send({ type: 'START_PING', target: pong });
+
+      // Wait for pong to receive
+      const [receivedEvent] = await pongPromise;
+      assert.equal(receivedEvent.type, 'PING');
+
+      // Setup detection for ping receiving PONG
+      const pingPromise = waitForEventReceived(ping, ['PONG']);
+
+      // Pong responds
+      pong.send({ type: 'RESPOND', target: ping });
+
+      // Wait for ping to receive
+      const [pongEvent] = await pingPromise;
+      assert.equal(pongEvent.type, 'PONG');
+    } finally {
+      ping.stop();
+      pong.stop();
+    }
+  });
+});
+```
+
+### Pattern: Event Source Filtering
+
+Test events from specific actor sources.
+
+```typescript
+describe('Multi-Child Event Filtering', () => {
+  it('should filter events by source actor', async () => {
+    const parent = createActor(parentMachine);
+
+    // Parent spawns multiple children: child-1, child-2, child-3
+    parent.send({ type: 'SPAWN_CHILDREN', count: 3 });
+
+    // Wait for events only from child-2
+    const events = await runUntilEventReceivedWith(
+      parent,
+      { otherActorId: 'child-2', timeout: 2000 },
+      ['READY', 'COMPLETE'],
+    );
+
+    // Should only have events from child-2
+    assert.equal(events.length, 2);
+    assert.equal(events[0].type, 'READY');
+    assert.equal(events[1].type, 'COMPLETE');
+  });
+
+  it('should filter events by pattern', async () => {
+    const parent = createActor(parentMachine);
+
+    // Filter events from any child matching pattern
+    const events = await runUntilEventReceivedWith(
+      parent,
+      { otherActorId: /^child-\d+$/ },
+      ['STATUS'],
+    );
+
+    assert.equal(events[0].type, 'STATUS');
+  });
+});
+```
+
+---
+
+## Timeout and Error Testing
+
+### Pattern: Testing Timeout Scenarios
+
+Verify actors handle timeouts correctly.
+
+```typescript
+describe('Timeout Handling', () => {
+  it('should timeout if actor takes too long', async () => {
+    const actor = createActor(slowMachine);
+
+    await assert.rejects(
+      runUntilDoneWith(actor, { timeout: 100 }),
+      (err: Error) => {
+        assert.match(err.message, /did not complete in 100ms/);
+        return true;
+      },
+    );
+  });
+
+  it('should complete within timeout', async () => {
+    const actor = createActor(fastMachine);
+
+    // Should not timeout
+    const output = await runUntilDoneWith(actor, { timeout: 1000 });
+    assert.ok(output);
+  });
+
+  it('should work with infinite timeout', async () => {
+    const actor = createActor(unpredictableMachine);
+
+    // No timeout
+    const output = await runUntilDoneWith(actor, { timeout: Infinity });
+    assert.ok(output);
+  });
+});
+```
+
+### Pattern: Error State Testing
+
+Test error handling and recovery.
+
+```typescript
+describe('Error Handling', () => {
+  it('should transition to error state on failure', async () => {
+    const actor = createActor(fetchMachine);
+
+    actor.send({ type: 'FETCH' });
+    actor.send({ type: 'ERROR', error: new Error('Network failed') });
+
+    const snapshot = await runUntilSnapshot(actor, (s) => s.matches('error'));
+
+    assert.ok(snapshot.context.error);
+    assert.match(snapshot.context.error.message, /Network failed/);
+  });
+
+  it('should retry after error', async () => {
+    const actor = createActor(retryMachine);
+
+    actor.send({ type: 'FETCH' });
+    actor.send({ type: 'ERROR' });
+
+    // Should transition to error
+    await waitForSnapshot(actor, (s) => s.matches('error'));
+
+    // Send retry
+    actor.send({ type: 'RETRY' });
+
+    // Should transition back to loading
+    const snapshot = await waitForSnapshot(actor, (s) => s.matches('loading'));
+
+    assert.ok(snapshot.matches('loading'));
+    actor.stop();
+  });
+});
+```
+
+---
+
+## Integration Testing Patterns
+
+### Pattern: End-to-End Flow Testing
+
+Test complete user flows through state machines.
+
+```typescript
+describe('User Registration Flow', () => {
+  it('should complete full registration', async () => {
+    const actor = createActor(registrationMachine);
+
+    // Start registration
+    const idleToForm = waitForTransition(
+      actor,
+      'registration.idle',
+      'registration.form',
+    );
+    actor.send({ type: 'START_REGISTRATION' });
+    await idleToForm;
+
+    // Fill form
+    actor.send({
+      type: 'SUBMIT_FORM',
+      data: { email: 'user@example.com', password: 'secure123' },
+    });
+
+    // Wait for validation
+    await waitForSnapshot(actor, (s) => s.matches('validating'));
+
+    // Simulate validation success
+    actor.send({ type: 'VALIDATION_SUCCESS' });
+
+    // Wait for API call
+    await waitForSnapshot(actor, (s) => s.matches('submitting'));
+
+    // Simulate API success
+    actor.send({
+      type: 'API_SUCCESS',
+      userId: '123',
+    });
+
+    // Should reach success state
+    const snapshot = await waitForSnapshot(actor, (s) => s.matches('success'));
+
+    assert.equal(snapshot.context.userId, '123');
+    actor.stop();
+  });
+});
+```
+
+### Pattern: Testing with External Services
+
+Test actors that interact with external services.
+
+```typescript
+import { vi } from 'vitest';
+
+describe('API Integration', () => {
+  it('should call API and handle response', async () => {
+    // Mock API
+    const mockFetch = vi.fn().mockResolvedValue({
+      json: async () => ({ id: '123', name: 'Test' }),
+    });
+
+    const machine = setup({
+      actors: {
+        fetchUser: fromPromise(async ({ input }) => {
+          const response = await mockFetch(`/api/users/${input.id}`);
+          return response.json();
+        }),
+      },
+    }).createMachine({...});
+
+    const actor = createActor(machine);
+
+    actor.send({ type: 'FETCH_USER', id: '123' });
+
+    const snapshot = await runUntilSnapshot(
+      actor,
+      (s) => s.context.userData !== null
+    );
+
+    assert.ok(mockFetch.calledOnce);
+    assert.equal(snapshot.context.userData.id, '123');
+  });
+});
+```
+
+---
+
+## Debugging Failed Tests
+
+### Pattern: Adding Debug Logging
+
+Use logger and inspector for debugging.
+
+```typescript
+describe('Debugging Failed Test', () => {
+  it('should debug with logger', async () => {
+    const actor = createActor(problemMachine);
+
+    const snapshot = await runUntilSnapshotWith(
+      actor,
+      {
+        logger: (...args) => console.log('[DEBUG]', ...args),
+        timeout: 5000,
+      },
+      (s) => s.matches('targetState'),
+    );
+
+    // Logs will show all state transitions and actions
+  });
+
+  it('should debug with inspector', async () => {
+    const actor = createActor(problemMachine);
+    const events: any[] = [];
+
+    const snapshot = await runUntilSnapshotWith(
+      actor,
+      {
+        inspector: (event) => {
+          events.push(event);
+          console.log('Inspection:', event.type);
+        },
+        timeout: 5000,
+      },
+      (s) => s.matches('targetState'),
+    );
+
+    // Inspect collected events
+    console.log('All events:', events);
+  });
+});
+```
+
+### Pattern: Incremental Testing
+
+Break complex tests into smaller steps.
+
+```typescript
+describe('Complex Flow - Incremental', () => {
+  it('Step 1: should start correctly', async () => {
+    const actor = createActor(complexMachine);
+    actor.send({ type: 'START' });
+
+    await waitForSnapshot(actor, (s) => s.matches('started'));
+    actor.stop();
+  });
+
+  it('Step 2: should process data', async () => {
+    const actor = createActor(complexMachine);
+    actor.send({ type: 'START' });
+    await waitForSnapshot(actor, (s) => s.matches('started'));
+
+    actor.send({ type: 'PROCESS', data: 'test' });
+    await waitForSnapshot(actor, (s) => s.matches('processing'));
+
+    actor.stop();
+  });
+
+  it('Step 3: should complete', async () => {
+    const actor = createActor(complexMachine);
+    actor.send({ type: 'START' });
+    await waitForSnapshot(actor, (s) => s.matches('started'));
+
+    actor.send({ type: 'PROCESS', data: 'test' });
+    await waitForSnapshot(actor, (s) => s.matches('processing'));
+
+    actor.send({ type: 'COMPLETE' });
+    const snapshot = await runUntilSnapshot(actor, (s) => s.matches('done'));
+
+    assert.ok(snapshot.matches('done'));
+  });
+});
+```
+
+---
+
+## Performance Testing
+
+### Pattern: Testing Timing Constraints
+
+Verify actors meet performance requirements.
+
+```typescript
+describe('Performance', () => {
+  it('should complete within 100ms', async () => {
+    const start = Date.now();
+    const actor = createActor(fastMachine);
+
+    await runUntilDoneWith(actor, { timeout: 100 });
+
+    const elapsed = Date.now() - start;
+    assert.ok(elapsed < 100, `Took ${elapsed}ms, expected < 100ms`);
+  });
+
+  it('should handle burst of events', async () => {
+    const actor = createActor(eventHandlerMachine);
+
+    // Send many events rapidly
+    const promise = waitForSnapshot(
+      actor,
+      (s) => s.context.processedCount === 1000,
+    );
+
+    for (let i = 0; i < 1000; i++) {
+      actor.send({ type: 'PROCESS', id: i });
+    }
+
+    const snapshot = await promise;
+    assert.equal(snapshot.context.processedCount, 1000);
+
+    actor.stop();
+  });
+});
+```
+
+### Pattern: Memory Leak Detection
+
+Test for memory leaks in long-running actors.
+
+```typescript
+describe('Memory Leaks', () => {
+  it('should not leak memory with many iterations', async () => {
+    const iterations = 1000;
+
+    for (let i = 0; i < iterations; i++) {
+      const actor = createActor(myMachine);
+      await runUntilDone(actor);
+      // Actor is stopped by runUntilDone
+    }
+
+    // If test completes, no obvious leaks
+    // Use memory profiling tools for deeper analysis
+  });
+});
+```
+
+---
+
+## Advanced TypeScript Patterns
+
+### Pattern: Generic Test Helpers
+
+Create reusable, type-safe test utilities.
+
+```typescript
+async function testMachineOutput<TLogic extends AnyActorLogic>(
+  logic: TLogic,
+  input: InputFrom<TLogic>,
+  expectedOutput: OutputFrom<TLogic>,
+) {
+  const actor = createActor(logic, { input });
+  const output = await runUntilDone(actor);
+
+  assert.deepEqual(output, expectedOutput);
+}
+
+// Usage
+await testMachineOutput(promiseMachine, 'input', 'expected-output');
+```
+
+### Pattern: Type-Safe Event Testing
+
+Create helpers with full type inference.
+
+```typescript
+function createEmittedTester<TMachine extends AnyStateMachineActor>(
+  machine: TMachine,
+) {
+  return async (
+    emittedTypes: Array<EmittedFrom<TMachine>['type']>,
+    assertions: (events: Array<EmittedFrom<TMachine>>) => void,
+  ) => {
+    const actor = createActor(machine);
+    const events = await runUntilEmitted(actor, emittedTypes);
+    assertions(events);
+  };
+}
+
+// Usage with full type safety
+const testEmitted = createEmittedTester(myMachine);
+
+await testEmitted(['EVENT1', 'EVENT2'], (events) => {
+  // events is fully typed as Array<EmittedFrom<typeof myMachine>>
+  assert.equal(events[0].type, 'EVENT1');
+  assert.equal(events[1].type, 'EVENT2');
+});
+```
+
+### Pattern: Conditional Type Guards
+
+Use type guards for snapshot testing.
+
+```typescript
+function isErrorState(
+  snapshot: SnapshotFrom<typeof machine>,
+): snapshot is SnapshotFrom<typeof machine> & { context: { error: Error } } {
+  return snapshot.matches('error') && snapshot.context.error !== null;
+}
+
+it('should reach error state with error', async () => {
+  const actor = createActor(machine);
+
+  actor.send({ type: 'TRIGGER_ERROR' });
+
+  const snapshot = await runUntilSnapshot(actor, isErrorState);
+
+  // TypeScript knows snapshot.context.error is Error
+  assert.equal(snapshot.context.error.message, 'Expected error');
+});
+```
+
+---
+
+## Best Practice Checklist
+
+### Test Organization
+
+- ✅ Use `describe` blocks for logical grouping
+- ✅ Extract shared setup to `beforeEach`
+- ✅ Clean up actors in `afterEach` if using `waitFor*`
+- ✅ Use factory functions for actor creation
+- ✅ Keep tests focused on single behavior
+
+### Currying
+
+- ✅ Curry repeated patterns in `beforeEach`
+- ✅ Type curried functions explicitly
+- ✅ Use multi-level currying for complex scenarios
+- ✅ Create reusable helpers with preset options
+
+### Assertions
+
+- ✅ Assert on specific values, not just truthiness
+- ✅ Use snapshot matchers for complex state
+- ✅ Test both success and error paths
+- ✅ Verify context changes, not just state values
+
+### Performance
+
+- ✅ Set explicit timeouts for slow operations
+- ✅ Keep timeouts < test framework timeout
+- ✅ Test timing constraints when critical
+- ✅ Profile for memory leaks in long-running tests
+
+### Debugging
+
+- ✅ Add logger for failing tests
+- ✅ Use inspector to see all events
+- ✅ Break complex tests into steps
+- ✅ Increase timeout to isolate timing issues
+
+---
+
+## See Also
+
+- [Core Functions Reference](./core-functions.md) - Detailed API documentation
+- [Options & Types](./options-types.md) - AuditionOptions and TypeScript types