feat(smartstate): Add middleware, computed, batching, selector memoization, AbortSignal support, and Web Component Context Protocol provider

changelog.md

@@ -1,5 +1,17 @@
 # Changelog
 
+## 2026-02-27 - 2.1.0 - feat(smartstate)
+Add middleware, computed, batching, selector memoization, AbortSignal support, and Web Component Context Protocol provider
+
+- Introduce StatePart middleware API (addMiddleware) — middleware runs sequentially before validation/persistence and can transform or reject a state change.
+- Add computed derived observables: standalone computed(sources, fn) and Smartstate.computed to derive values from multiple state parts (lazy subscription).
+- Add batching support via Smartstate.batch(fn), isBatching flag, and deferred notifications to batch multiple updates and flush only at the outermost level.
+- Enhance select() with selector memoization (WeakMap cache and shareReplay) and optional AbortSignal support (auto-unsubscribe).
+- Extend waitUntilPresent() to accept timeout and AbortSignal options and maintain backward-compatible numeric timeout argument.
+- Add attachContextProvider(element, options) to bridge state parts to Web Component Context Protocol (context-request events) with subscribe/unsubscribe handling.
+- Update StatePart.setState to run middleware, persist processed state atomically, and defer notifications to batching when applicable.
+- Tests and README updated to document new features, behaviors, and examples.
+
 ## 2026-02-27 - 2.0.31 - fix(deps)
 bump devDependencies and fix README license path
 

npmextra.json

@@ -16,7 +16,7 @@
       "githost": "code.foss.global",
       "gitscope": "push.rocks",
       "gitrepo": "smartstate",
-      "description": "A package for handling and managing state in applications.",
+      "description": "A TypeScript-first reactive state management library with middleware, computed state, batching, persistence, and Web Component Context Protocol support.",
       "npmPackagename": "@push.rocks/smartstate",
       "license": "MIT",
       "keywords": [
@@ -29,7 +29,13 @@
         "state selection",
         "state notification",
         "asynchronous state",
-        "cumulative notification"
+        "cumulative notification",
+        "middleware",
+        "computed state",
+        "batch updates",
+        "context protocol",
+        "web components",
+        "AbortSignal"
       ]
     },
     "release": {

package.json

@@ -2,7 +2,7 @@
   "name": "@push.rocks/smartstate",
   "version": "2.0.31",
   "private": false,
-  "description": "A package for handling and managing state in applications.",
+  "description": "A TypeScript-first reactive state management library with middleware, computed state, batching, persistence, and Web Component Context Protocol support.",
   "main": "dist_ts/index.js",
   "typings": "dist_ts/index.d.ts",
   "type": "module",
@@ -22,7 +22,6 @@
     "@types/node": "^25.3.2"
   },
   "dependencies": {
-    "@push.rocks/lik": "^6.2.2",
     "@push.rocks/smarthash": "^3.2.6",
     "@push.rocks/smartjson": "^6.0.0",
     "@push.rocks/smartpromise": "^4.2.3",
@@ -54,7 +53,13 @@
     "state selection",
     "state notification",
     "asynchronous state",
-    "cumulative notification"
+    "cumulative notification",
+    "middleware",
+    "computed state",
+    "batch updates",
+    "context protocol",
+    "web components",
+    "AbortSignal"
   ],
   "homepage": "https://code.foss.global/push.rocks/smartstate",
   "repository": {

pnpm-lock.yaml

@@ -8,9 +8,6 @@ importers:
 
   .:
     dependencies:
-      '@push.rocks/lik':
-        specifier: ^6.2.2
-        version: 6.2.2
       '@push.rocks/smarthash':
         specifier: ^3.2.6
         version: 3.2.6

readme.hints.md

@@ -1,6 +1,6 @@
 # Smartstate Implementation Notes
 
-## Current API (as of v2.0.28+)
+## Current API (as of v2.0.31)
 
 ### State Part Initialization
 - State parts can be created with different init modes: 'soft' (default), 'mandatory', 'force', 'persistent'
@@ -8,50 +8,67 @@
   - 'mandatory' - requires state part to not exist, fails if it does
   - 'force' - always creates new state part, overwriting any existing
   - 'persistent' - like 'soft' but with WebStore persistence (IndexedDB)
-- Persistent mode automatically calls init() internally - no need to call it manually
+- Persistent mode automatically calls init() internally
 - State merge order fixed: initial state takes precedence over stored state
 
 ### Actions
 - Actions are created with `createAction()` method
-- Two ways to dispatch actions:
+- Two ways to dispatch: `stateAction.trigger(payload)` or `statePart.dispatchAction(stateAction, payload)`
-  1. `stateAction.trigger(payload)` - returns Promise<TStatePayload>
+- Both return Promise<TStatePayload>
-  2. `await statePart.dispatchAction(stateAction, payload)` - returns Promise<TStatePayload>
-- Both methods return the same Promise, providing flexibility in usage
 
 ### State Management Methods
-- `select()` - returns Observable with startWith current state, filters undefined states
+- `select(fn?, { signal? })` - returns Observable, memoized by selector fn ref, supports AbortSignal
-- `waitUntilPresent()` - waits for specific state condition
+- `waitUntilPresent(fn?, number | { timeoutMs?, signal? })` - waits for state condition, backward compat with number arg
 - `stateSetup()` - async state initialization with cumulative defer
 - `notifyChangeCumulative()` - defers notification to end of call stack
 - `getState()` - returns current state or undefined
-- `setState()` - validates state before setting, notifies only on actual changes
+- `setState()` - runs middleware, validates, persists, notifies
+- `addMiddleware(fn)` - intercepts setState, returns removal function
+
+### Middleware
+- Type: `(newState, oldState) => newState | Promise<newState>`
+- Runs sequentially in insertion order before validation/persistence
+- Throw to reject state changes (atomic — state unchanged on error)
+- Does NOT run during initial createStatePart() hydration
+
+### Selector Memoization
+- Uses WeakMap<Function, Observable> for fn-keyed cache
+- `defaultSelectObservable` for no-arg select()
+- Wrapped in `shareReplay({ bufferSize: 1, refCount: true })`
+- NOT cached when AbortSignal is provided
+
+### Batch Updates
+- `smartstate.batch(async () => {...})` — defers notifications until batch completes
+- Supports nesting — only flushes at outermost level
+- StatePart has `smartstateRef` set by `createStatePart()` for batch awareness
+- State parts created via `new StatePart()` directly work without batching
+
+### Computed State
+- `computed(sources, fn)` — standalone function using `combineLatest` + `map`
+- Also available as `smartstate.computed(sources, fn)`
+- Lazy — only subscribes when subscribed to
+
+### Context Protocol Bridge
+- `attachContextProvider(element, { context, statePart, selectorFn? })` — returns cleanup fn
+- Listens for `context-request` CustomEvent on element
+- Supports one-shot and subscription modes
+- Works with Lit @consume(), FAST, or any Context Protocol consumer
 
 ### State Hash Detection
 - Uses SHA256 hash to detect actual state changes
-- Fixed: Hash comparison now properly awaits async hash calculation
+- Hash comparison properly awaits async hash calculation
 - Prevents duplicate notifications for identical state values
-- `notifyChange()` is now async to support proper hash comparison
 
 ### State Validation
 - Basic validation ensures state is not null/undefined
-- `validateState()` method can be overridden in subclasses for custom validation
+- `validateState()` can be overridden in subclasses
-- Validation runs on both setState() and when loading from persistent storage
 
-### Type System
+### Key Notes
-- Can use either enums or string literal types for state part names
+- `smartstateRef` creates circular ref between StatePart and Smartstate
-- Test uses simple string types: `type TMyStateParts = 'testStatePart'`
+- Use `===` not deep equality for StatePart comparison in tests
-- State can be undefined initially, handled properly in select() and other methods
+- Direct rxjs imports used for: Observable, shareReplay, takeUntil, combineLatest, map
 
-## Recent Fixes (v2.0.24+)
+## Dependency Versions (v2.0.31)
-1. Fixed state hash bug - now properly compares hash values instead of promises
-2. Fixed state initialization merge order - initial state now takes precedence
-3. Ensured stateStore is properly typed as potentially undefined
-4. Simplified init mode logic with clear behavior for each mode
-5. Added state validation with extensible validateState() method
-6. Made notifyChange() async to support proper hash comparison
-7. Updated select() to filter undefined states
-
-## Dependency Versions (v2.0.30)
 - @git.zone/tsbuild: ^4.1.2
 - @git.zone/tsbundle: ^2.9.0
 - @git.zone/tsrun: ^2.0.1

readme.md

@@ -1,6 +1,6 @@
 # @push.rocks/smartstate
 
-A powerful TypeScript library for elegant state management using RxJS and reactive programming patterns 🚀
+A TypeScript-first reactive state management library with middleware, computed state, batching, persistence, and Web Component Context Protocol support 🚀
 
 ## Issue Reporting and Security
 
@@ -8,306 +8,311 @@ For reporting bugs, issues, or security vulnerabilities, please visit [community
 
 ## Install
 
-To install `@push.rocks/smartstate`, you can use pnpm, npm, or yarn:
+```bash
+pnpm install @push.rocks/smartstate --save
+```
+
+Or with npm:
 
 ```bash
-# Using pnpm (recommended)
-pnpm install @push.rocks/smartstate --save
-
-# Using npm
 npm install @push.rocks/smartstate --save
-
-# Using yarn
-yarn add @push.rocks/smartstate
 ```
 
 ## Usage
 
-The `@push.rocks/smartstate` library provides an elegant way to handle state within your JavaScript or TypeScript projects, leveraging the power of Reactive Extensions (RxJS) and a structured state management strategy.
+### Quick Start
-
-### Getting Started
-
-Import the necessary components from the library:
 
 ```typescript
-import { Smartstate, StatePart, StateAction } from '@push.rocks/smartstate';
+import { Smartstate } from '@push.rocks/smartstate';
+
+// 1. Define your state part names
+type AppParts = 'user' | 'settings';
+
+// 2. Create the root instance
+const state = new Smartstate<AppParts>();
+
+// 3. Create state parts with initial values
+const userState = await state.getStatePart<{ name: string; loggedIn: boolean }>('user', {
+  name: '',
+  loggedIn: false,
+});
+
+// 4. Subscribe to changes
+userState.select((s) => s.name).subscribe((name) => {
+  console.log('Name changed:', name);
+});
+
+// 5. Update state
+await userState.setState({ name: 'Alice', loggedIn: true });
 ```
 
-### Creating a SmartState Instance
+### State Parts & Init Modes
 
-`Smartstate` acts as the container for your state parts. Think of it as the root of your state management structure:
+State parts are isolated, typed units of state. Create them with `getStatePart()`:
 
 ```typescript
-const myAppSmartState = new Smartstate<YourStatePartNamesEnum>();
+const part = await state.getStatePart<IMyState>(name, initialState, initMode);
 ```
 
-### Understanding Init Modes
+| Init Mode | Behavior |
+|-----------|----------|
+| `'soft'` (default) | Returns existing if found, creates new otherwise |
+| `'mandatory'` | Throws if state part already exists |
+| `'force'` | Always creates new, overwrites existing |
+| `'persistent'` | Like `'soft'` but persists to IndexedDB via WebStore |
 
-When creating state parts, you can specify different initialization modes:
+#### Persistent State
-
-| Mode | Description |
-|------|-------------|
-| `'soft'` | Default. Returns existing state part if it exists, creates new if not |
-| `'mandatory'` | Requires state part to not exist, throws error if it does |
-| `'force'` | Always creates new state part, overwriting any existing one |
-| `'persistent'` | Like 'soft' but with WebStore persistence using IndexedDB |
-
-### Defining State Parts
-
-State parts represent separable sections of your state, making it easier to manage and modularize. Define state part names using either enums or string literal types:
 
 ```typescript
-// Option 1: Using enums
+const settings = await state.getStatePart('settings', { theme: 'dark' }, 'persistent');
-enum AppStateParts {
+// Automatically saved to IndexedDB. On next app load, persisted values override defaults.
-  UserState = 'UserState',
-  SettingsState = 'SettingsState'
-}
-
-// Option 2: Using string literal types (simpler approach)
-type AppStateParts = 'UserState' | 'SettingsState';
 ```
 
-Create a state part within your `Smartstate` instance:
+### Selecting State
+
+`select()` returns an RxJS Observable that emits the current value immediately and on every change:
 
 ```typescript
-interface IUserState {
+// Full state
-  isLoggedIn: boolean;
+userState.select().subscribe((state) => console.log(state));
-  username?: string;
-}
 
-const userStatePart = await myAppSmartState.getStatePart<IUserState>(
+// Derived value via selector
-  AppStateParts.UserState,
+userState.select((s) => s.name).subscribe((name) => console.log(name));
-  { isLoggedIn: false }, // Initial state
+```
-  'soft' // Init mode (optional, defaults to 'soft')
+
+Selectors are **memoized** — calling `select(fn)` with the same function reference returns the same cached Observable, shared across all subscribers.
+
+#### AbortSignal Support
+
+Clean up subscriptions without manual `unsubscribe()`:
+
+```typescript
+const controller = new AbortController();
+
+userState.select((s) => s.name, { signal: controller.signal }).subscribe((name) => {
+  console.log(name); // stops receiving when aborted
+});
+
+// Later: clean up
+controller.abort();
+```
+
+### Actions
+
+Actions provide controlled, named state mutations:
+
+```typescript
+const login = userState.createAction<{ name: string }>(async (statePart, payload) => {
+  return { ...statePart.getState(), name: payload.name, loggedIn: true };
+});
+
+// Two equivalent ways to dispatch:
+await login.trigger({ name: 'Alice' });
+await userState.dispatchAction(login, { name: 'Alice' });
+```
+
+### Middleware
+
+Intercept every `setState()` call to transform, validate, or reject state changes:
+
+```typescript
+// Logging middleware
+userState.addMiddleware((newState, oldState) => {
+  console.log('State changing from', oldState, 'to', newState);
+  return newState;
+});
+
+// Validation middleware — throw to reject the change
+userState.addMiddleware((newState) => {
+  if (!newState.name) throw new Error('Name is required');
+  return newState;
+});
+
+// Transform middleware
+userState.addMiddleware((newState) => {
+  return { ...newState, name: newState.name.trim() };
+});
+
+// Removal — addMiddleware returns a dispose function
+const remove = userState.addMiddleware(myMiddleware);
+remove(); // middleware no longer runs
+```
+
+Middleware runs sequentially in insertion order. If any middleware throws, the state is unchanged (atomic).
+
+### Computed / Derived State
+
+Derive reactive values from one or more state parts:
+
+```typescript
+import { computed } from '@push.rocks/smartstate';
+
+const userState = await state.getStatePart('user', { firstName: 'Jane', lastName: 'Doe' });
+const settingsState = await state.getStatePart('settings', { locale: 'en' });
+
+// Standalone function
+const greeting$ = computed(
+  [userState, settingsState],
+  (user, settings) => `Hello, ${user.firstName} (${settings.locale})`,
 );
+
+greeting$.subscribe((msg) => console.log(msg));
+// => "Hello, Jane (en)"
+
+// Also available as a method on Smartstate:
+const greeting2$ = state.computed([userState, settingsState], (user, settings) => /* ... */);
 ```
 
-### Subscribing to State Changes
+Computed observables are **lazy** — they only subscribe to sources when someone subscribes to them.
 
-Subscribe to changes in a state part to perform actions accordingly:
+### Batch Updates
+
+Update multiple state parts without intermediate notifications:
 
 ```typescript
-// The select() method automatically filters out undefined states
+const partA = await state.getStatePart('a', { value: 1 });
-userStatePart.select().subscribe((currentState) => {
+const partB = await state.getStatePart('b', { value: 2 });
-  console.log(`User Logged In: ${currentState.isLoggedIn}`);
+
+// Subscribers see no updates during the batch — only after it completes
+await state.batch(async () => {
+  await partA.setState({ value: 10 });
+  await partB.setState({ value: 20 });
+  // Notifications are deferred here
 });
-```
+// Both subscribers now fire with their new values
 
-Select a specific part of your state with a selector function:
+// Nested batches are supported — flush happens at the outermost level
-
+await state.batch(async () => {
-```typescript
+  await partA.setState({ value: 100 });
-userStatePart.select(state => state.username).subscribe((username) => {
+  await state.batch(async () => {
-  if (username) {
+    await partB.setState({ value: 200 });
-    console.log(`Current user: ${username}`);
+  });
-  }
+  // Still deferred
 });
+// Now both fire
 ```
 
-### Modifying State with Actions
+### Waiting for State
 
-Create actions to modify the state in a controlled manner:
+Wait for a specific state condition to be met:
 
 ```typescript
-interface ILoginPayload {
+// Wait for any truthy state
-  username: string;
+const currentState = await userState.waitUntilPresent();
-}
 
-const loginUserAction = userStatePart.createAction<ILoginPayload>(async (statePart, payload) => {
+// Wait for a specific condition
-  return { ...statePart.getState(), isLoggedIn: true, username: payload.username };
+const name = await userState.waitUntilPresent((s) => s.name || undefined);
-});
 
-// Dispatch the action to update the state
+// With timeout (backward compatible)
-const newState = await loginUserAction.trigger({ username: 'johnDoe' });
+const name = await userState.waitUntilPresent((s) => s.name || undefined, 5000);
-```
 
-### Dispatching Actions
+// With AbortSignal
-
+const controller = new AbortController();
-There are two ways to dispatch actions:
-
-```typescript
-// Method 1: Using trigger on the action (returns promise)
-const newState = await loginUserAction.trigger({ username: 'johnDoe' });
-
-// Method 2: Using dispatchAction on the state part (returns promise)
-const newState = await userStatePart.dispatchAction(loginUserAction, { username: 'johnDoe' });
-```
-
-Both methods return a Promise with the new state payload.
-
-### Additional State Methods
-
-`StatePart` provides several useful methods for state management:
-
-```typescript
-// Get current state (may be undefined initially)
-const currentState = userStatePart.getState();
-if (currentState) {
-  console.log('Current user:', currentState.username);
-}
-
-// Wait for state to be present
-await userStatePart.waitUntilPresent();
-
-// Wait for a specific property to be present
-await userStatePart.waitUntilPresent(state => state.username);
-
-// Wait with a timeout (throws error if condition not met within timeout)
 try {
-  await userStatePart.waitUntilPresent(state => state.username, 5000); // 5 second timeout
+  const name = await userState.waitUntilPresent(
-} catch (error) {
+    (s) => s.name || undefined,
-  console.error('Timed out waiting for username');
+    { timeoutMs: 5000, signal: controller.signal },
+  );
+} catch (e) {
+  // 'Aborted' or timeout error
 }
-
-// Setup initial state with async operations
-await userStatePart.stateSetup(async (statePart) => {
-  const userData = await fetchUserData();
-  return { ...statePart.getState(), ...userData };
-});
-
-// Defer notification to end of call stack (debounced)
-userStatePart.notifyChangeCumulative();
 ```
 
-### Persistent State with WebStore
+### Context Protocol Bridge (Web Components)
 
-`Smartstate` supports persistent states using WebStore (IndexedDB-based storage), allowing you to maintain state across sessions:
+Expose state parts to web components via the [W3C Context Protocol](https://github.com/webcomponents-cg/community-protocols/blob/main/proposals/context.md):
 
 ```typescript
-const settingsStatePart = await myAppSmartState.getStatePart<ISettingsState>(
+import { attachContextProvider } from '@push.rocks/smartstate';
-  AppStateParts.SettingsState,
+
-  { theme: 'light' }, // Initial/default state
+// Define a context key
-  'persistent' // Mode
+const themeContext = Symbol('theme');
+
+// Attach a provider to a DOM element
+const cleanup = attachContextProvider(myElement, {
+  context: themeContext,
+  statePart: settingsState,
+  selectorFn: (s) => s.theme, // optional: provide derived value
+});
+
+// Any descendant can request this context:
+myElement.dispatchEvent(
+  new CustomEvent('context-request', {
+    bubbles: true,
+    composed: true,
+    detail: {
+      context: themeContext,
+      callback: (theme) => console.log('Theme:', theme),
+      subscribe: true, // receive updates on state changes
+    },
+  }),
 );
+
+// Cleanup when done
+cleanup();
 ```
 
-Persistent state automatically:
+This works with Lit's `@consume()` decorator, FAST, or any framework implementing the Context Protocol.
-- Saves state changes to IndexedDB
-- Restores state on application restart
-- Merges persisted values with defaults (persisted values take precedence)
-- Ensures atomic writes (persistence happens before memory update)
 
 ### State Validation
 
-`Smartstate` includes built-in state validation to ensure data integrity:
+Built-in null/undefined validation. Extend for custom rules:
 
 ```typescript
-// Basic validation (built-in) ensures state is not null or undefined
+class ValidatedPart<T> extends StatePart<string, T> {
-await userStatePart.setState(null); // Throws error: Invalid state structure
-
-// Custom validation by extending StatePart
-class ValidatedStatePart<T> extends StatePart<string, T> {
   protected validateState(stateArg: any): stateArg is T {
-    return super.validateState(stateArg) && /* your validation */;
+    return super.validateState(stateArg) && typeof stateArg.name === 'string';
   }
 }
 ```
 
-### Performance Optimization
+### Performance Features
 
-`Smartstate` includes advanced performance optimizations:
+- **SHA256 Change Detection** — identical state values don't trigger notifications, even with different object references
+- **Selector Memoization** — `select(fn)` caches observables by function reference, sharing one upstream subscription across all subscribers
+- **Cumulative Notifications** — `notifyChangeCumulative()` debounces rapid changes into a single notification
+- **Concurrent Safety** — simultaneous `getStatePart()` calls for the same name return the same promise, preventing duplicate creation
+- **Atomic Persistence** — WebStore writes complete before in-memory state updates, ensuring consistency
+- **Batch Deferred Notifications** — `batch()` suppresses all notifications until the batch completes
 
-- **🔒 Async State Hash Detection**: Uses SHA256 hashing to detect actual state changes, preventing unnecessary notifications when state values haven't truly changed
+## API Reference
-- **🚫 Duplicate Prevention**: Identical state updates are automatically filtered out
-- **📦 Cumulative Notifications**: Batch multiple state changes into a single notification using `notifyChangeCumulative()` with automatic debouncing
-- **🎯 Selective Subscriptions**: Use selectors to subscribe only to specific state properties
-- **✨ Undefined State Filtering**: The `select()` method automatically filters out undefined states
-- **⚡ Concurrent Access Safety**: Prevents race conditions when multiple calls request the same state part simultaneously
 
-### RxJS Integration
+### `Smartstate<T>`
 
-`Smartstate` leverages RxJS for reactive state management:
+| Method | Description |
+|--------|-------------|
+| `getStatePart(name, initial?, initMode?)` | Get or create a state part |
+| `batch(fn)` | Batch updates, defer notifications |
+| `computed(sources, fn)` | Create computed observable |
+| `isBatching` | Whether a batch is active |
 
-```typescript
+### `StatePart<TName, TPayload>`
-// State is exposed as an RxJS Subject
-const stateObservable = userStatePart.select();
 
-// Automatically starts with current state value
+| Method | Description |
-stateObservable.subscribe((state) => {
+|--------|-------------|
-  console.log('Current state:', state);
+| `getState()` | Get current state (or undefined) |
-});
+| `setState(newState)` | Set state (runs middleware, validates, persists, notifies) |
+| `select(selectorFn?, options?)` | Subscribe to state changes |
+| `createAction(actionDef)` | Create a named action |
+| `dispatchAction(action, payload)` | Dispatch an action |
+| `addMiddleware(fn)` | Add middleware, returns removal function |
+| `waitUntilPresent(selectorFn?, options?)` | Wait for state condition |
+| `notifyChange()` | Manually trigger notification |
+| `notifyChangeCumulative()` | Debounced notification |
+| `stateSetup(fn)` | Async state initialization |
 
-// Use selectors for specific properties
+### `StateAction<TState, TPayload>`
-userStatePart.select(state => state.username)
-  .pipe(
-    distinctUntilChanged(),
-    filter(username => username !== undefined)
-  )
-  .subscribe(username => {
-    console.log('Username changed:', username);
-  });
-```
 
-### Complete Example
+| Method | Description |
+|--------|-------------|
+| `trigger(payload)` | Dispatch the action |
 
-Here's a comprehensive example showcasing the power of `@push.rocks/smartstate`:
+### Standalone Functions
 
-```typescript
+| Function | Description |
-import { Smartstate, StatePart, StateAction } from '@push.rocks/smartstate';
+|----------|-------------|
-
+| `computed(sources, fn)` | Create computed observable from state parts |
-// Define your state structure
+| `attachContextProvider(element, options)` | Bridge state to Context Protocol |
-type AppStateParts = 'user' | 'settings' | 'cart';
-
-interface IUserState {
-  isLoggedIn: boolean;
-  username?: string;
-  email?: string;
-}
-
-interface ICartState {
-  items: Array<{ id: string; quantity: number }>;
-  total: number;
-}
-
-// Create the smartstate instance
-const appState = new Smartstate<AppStateParts>();
-
-// Initialize state parts
-const userState = await appState.getStatePart<IUserState>('user', {
-  isLoggedIn: false
-});
-
-const cartState = await appState.getStatePart<ICartState>('cart', {
-  items: [],
-  total: 0
-}, 'persistent'); // Persists across sessions
-
-// Create actions
-const loginAction = userState.createAction<{ username: string; email: string }>(
-  async (statePart, payload) => {
-    // Simulate API call
-    await new Promise(resolve => setTimeout(resolve, 1000));
-
-    return {
-      isLoggedIn: true,
-      username: payload.username,
-      email: payload.email
-    };
-  }
-);
-
-// Subscribe to changes
-userState.select(state => state.isLoggedIn).subscribe(isLoggedIn => {
-  console.log('Login status changed:', isLoggedIn);
-});
-
-// Dispatch actions
-await loginAction.trigger({ username: 'john', email: 'john@example.com' });
-```
-
-## Key Features
-
-| Feature | Description |
-|---------|-------------|
-| 🎯 **Type-safe** | Full TypeScript support with intelligent type inference |
-| ⚡ **Performance optimized** | Async state hash detection prevents unnecessary re-renders |
-| 💾 **Persistent state** | Built-in IndexedDB support for state persistence |
-| 🔄 **Reactive** | Powered by RxJS for elegant async handling |
-| 🧩 **Modular** | Organize state into logical, reusable parts |
-| ✅ **Validated** | Built-in state validation with extensible validation logic |
-| 🎭 **Flexible init modes** | Choose how state parts are initialized |
-| 📦 **Zero config** | Works out of the box with sensible defaults |
-| 🛡️ **Race condition safe** | Concurrent state part creation is handled safely |
-| ⏱️ **Timeout support** | `waitUntilPresent` supports optional timeouts |
 
 ## License and Legal Information
 

test/test.initialization.ts

@@ -10,10 +10,13 @@ interface ITestState {
   };
 }
 
+// ============================
+// Init mode tests
+// ============================
+
 tap.test('should handle soft init mode (default)', async () => {
   const state = new smartstate.Smartstate<TTestStateParts>();
 
-  // First creation
   const statePart1 = await state.getStatePart<ITestState>('initTest', {
     value: 1,
     nested: { data: 'initial' }
@@ -23,22 +26,19 @@ tap.test('should handle soft init mode (default)', async () => {
     nested: { data: 'initial' }
   });
 
-  // Second call should return existing
   const statePart2 = await state.getStatePart<ITestState>('initTest');
-  expect(statePart1).toEqual(statePart2);
+  expect(statePart1 === statePart2).toBeTrue();
 });
 
 tap.test('should handle mandatory init mode', async () => {
   const state = new smartstate.Smartstate<TTestStateParts>();
 
-  // First creation should succeed
   const statePart1 = await state.getStatePart<ITestState>('initTest', {
     value: 1,
     nested: { data: 'initial' }
   }, 'mandatory');
   expect(statePart1).toBeInstanceOf(smartstate.StatePart);
 
-  // Second call with mandatory should fail
   let error: Error | null = null;
   try {
     await state.getStatePart<ITestState>('initTest', {
@@ -55,20 +55,18 @@ tap.test('should handle mandatory init mode', async () => {
 tap.test('should handle force init mode', async () => {
   const state = new smartstate.Smartstate<TTestStateParts>();
 
-  // First creation
   const statePart1 = await state.getStatePart<ITestState>('forceTest', {
     value: 1,
     nested: { data: 'initial' }
   });
   expect(statePart1.getState()?.value).toEqual(1);
 
-  // Force should create new state part
   const statePart2 = await state.getStatePart<ITestState>('forceTest', {
     value: 2,
     nested: { data: 'forced' }
   }, 'force');
   expect(statePart2.getState()?.value).toEqual(2);
-  expect(statePart1).not.toEqual(statePart2);
+  expect(statePart1 === statePart2).toBeFalse();
 });
 
 tap.test('should handle missing initial state error', async () => {
@@ -92,7 +90,6 @@ tap.test('should handle state validation', async () => {
     nested: { data: 'initial' }
   });
 
-  // Setting null should fail validation
   let error: Error | null = null;
   try {
     await statePart.setState(null as any);
@@ -107,14 +104,11 @@ tap.test('should handle undefined state in select', async () => {
   const state = new smartstate.Smartstate<TTestStateParts>();
   const statePart = new smartstate.StatePart<TTestStateParts, ITestState>('initTest');
 
-  // Select should filter out undefined states
   const values: (ITestState | undefined)[] = [];
   statePart.select().subscribe(val => values.push(val));
 
-  // Initially undefined, should not emit
   expect(values).toHaveLength(0);
 
-  // After setting state, should emit
   await statePart.setState({
     value: 1,
     nested: { data: 'test' }
@@ -135,23 +129,504 @@ tap.test('should not notify on duplicate state', async () => {
   });
 
   let notificationCount = 0;
-  // Use select() to get initial value + changes
   statePart.select().subscribe(() => notificationCount++);
 
-  // Should have received initial state
   expect(notificationCount).toEqual(1);
 
-  // Set same state multiple times
   await statePart.setState({ value: 1, nested: { data: 'initial' } });
   await statePart.setState({ value: 1, nested: { data: 'initial' } });
   await statePart.setState({ value: 1, nested: { data: 'initial' } });
 
-  // Should still be 1 (no new notifications for duplicate state)
   expect(notificationCount).toEqual(1);
 
-  // Change state should notify
   await statePart.setState({ value: 2, nested: { data: 'changed' } });
   expect(notificationCount).toEqual(2);
 });
 
+// ============================
+// AbortSignal tests
+// ============================
+
+tap.test('select should complete when AbortSignal fires', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  });
+
+  const controller = new AbortController();
+  const values: any[] = [];
+  let completed = false;
+
+  statePart.select(undefined, { signal: controller.signal }).subscribe({
+    next: (v) => values.push(v),
+    complete: () => { completed = true; },
+  });
+
+  expect(values.length).toBeGreaterThanOrEqual(1);
+
+  controller.abort();
+  // Give microtask time
+  await new Promise<void>((r) => setTimeout(r, 10));
+
+  expect(completed).toBeTrue();
+});
+
+tap.test('select with pre-aborted signal should complete immediately', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  });
+
+  const controller = new AbortController();
+  controller.abort();
+
+  let completed = false;
+  statePart.select(undefined, { signal: controller.signal }).subscribe({
+    complete: () => { completed = true; },
+  });
+
+  await new Promise<void>((r) => setTimeout(r, 10));
+  expect(completed).toBeTrue();
+});
+
+tap.test('waitUntilPresent should reject when AbortSignal fires', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 0,
+    nested: { data: '' }
+  }, 'force');
+
+  const controller = new AbortController();
+
+  const promise = statePart.waitUntilPresent(
+    (s) => s.value > 100 ? s : undefined as any,
+    { signal: controller.signal }
+  );
+
+  // Abort before the condition can be met
+  setTimeout(() => controller.abort(), 20);
+
+  let error: Error | null = null;
+  try {
+    await promise;
+  } catch (e) {
+    error = e as Error;
+  }
+  expect(error).not.toBeNull();
+  expect(error?.message).toEqual('Aborted');
+});
+
+tap.test('waitUntilPresent should still work with numeric timeout (backward compat)', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 42,
+    nested: { data: 'present' }
+  }, 'force');
+
+  const result = await statePart.waitUntilPresent(undefined, 5000);
+  expect(result.value).toEqual(42);
+});
+
+// ============================
+// Middleware tests
+// ============================
+
+tap.test('middleware should transform state', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  }, 'force');
+
+  statePart.addMiddleware((newState, oldState) => {
+    return { ...newState, nested: { data: newState.nested.data.toUpperCase() } };
+  });
+
+  await statePart.setState({ value: 2, nested: { data: 'hello' } });
+  expect(statePart.getState().nested.data).toEqual('HELLO');
+});
+
+tap.test('middleware should reject state changes on throw', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  }, 'force');
+
+  statePart.addMiddleware((newState) => {
+    if (newState.value < 0) {
+      throw new Error('Value must be non-negative');
+    }
+    return newState;
+  });
+
+  let error: Error | null = null;
+  try {
+    await statePart.setState({ value: -1, nested: { data: 'bad' } });
+  } catch (e) {
+    error = e as Error;
+  }
+
+  expect(error).not.toBeNull();
+  expect(error?.message).toEqual('Value must be non-negative');
+  // State should be unchanged
+  expect(statePart.getState().value).toEqual(1);
+});
+
+tap.test('multiple middlewares should run in order', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  }, 'force');
+
+  const order: number[] = [];
+
+  statePart.addMiddleware((newState) => {
+    order.push(1);
+    return { ...newState, value: newState.value + 10 };
+  });
+
+  statePart.addMiddleware((newState) => {
+    order.push(2);
+    return { ...newState, value: newState.value * 2 };
+  });
+
+  await statePart.setState({ value: 5, nested: { data: 'test' } });
+  expect(order).toEqual([1, 2]);
+  // (5 + 10) * 2 = 30
+  expect(statePart.getState().value).toEqual(30);
+});
+
+tap.test('middleware removal should work', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  }, 'force');
+
+  const remove = statePart.addMiddleware((newState) => {
+    return { ...newState, value: newState.value * 100 };
+  });
+
+  await statePart.setState({ value: 2, nested: { data: 'test' } });
+  expect(statePart.getState().value).toEqual(200);
+
+  remove();
+
+  await statePart.setState({ value: 3, nested: { data: 'test' } });
+  expect(statePart.getState().value).toEqual(3);
+});
+
+// ============================
+// Selector memoization tests
+// ============================
+
+tap.test('select with same selector fn should return cached observable', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  }, 'force');
+
+  const selector = (s: ITestState) => s.value;
+  const obs1 = statePart.select(selector);
+  const obs2 = statePart.select(selector);
+  expect(obs1).toEqual(obs2);
+});
+
+tap.test('select with no args should return cached observable', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  }, 'force');
+
+  const obs1 = statePart.select();
+  const obs2 = statePart.select();
+  expect(obs1).toEqual(obs2);
+});
+
+tap.test('select with different selectors should return different observables', async () => {
+  const state = new smartstate.Smartstate<TTestStateParts>();
+  const statePart = await state.getStatePart<ITestState>('initTest', {
+    value: 1,
+    nested: { data: 'initial' }
+  }, 'force');
+
+  const obs1 = statePart.select((s) => s.value);
+  const obs2 = statePart.select((s) => s.nested);
+  expect(obs1).not.toEqual(obs2);
+});
+
+// ============================
+// Batch update tests
+// ============================
+
+tap.test('batch should defer notifications until complete', async () => {
+  type TBatchParts = 'partA' | 'partB';
+  const state = new smartstate.Smartstate<TBatchParts>();
+  const partA = await state.getStatePart<ITestState>('partA', {
+    value: 1,
+    nested: { data: 'a' }
+  });
+  const partB = await state.getStatePart<ITestState>('partB', {
+    value: 2,
+    nested: { data: 'b' }
+  });
+
+  const notificationsA: number[] = [];
+  const notificationsB: number[] = [];
+
+  partA.select((s) => s.value).subscribe((v) => notificationsA.push(v));
+  partB.select((s) => s.value).subscribe((v) => notificationsB.push(v));
+
+  // Reset after initial notifications
+  notificationsA.length = 0;
+  notificationsB.length = 0;
+
+  await state.batch(async () => {
+    await partA.setState({ value: 10, nested: { data: 'aa' } });
+    await partB.setState({ value: 20, nested: { data: 'bb' } });
+
+    // During batch, no notifications yet
+    expect(notificationsA).toHaveLength(0);
+    expect(notificationsB).toHaveLength(0);
+  });
+
+  // After batch, both should have notified
+  expect(notificationsA).toContain(10);
+  expect(notificationsB).toContain(20);
+});
+
+tap.test('nested batches should only flush at outermost level', async () => {
+  type TBatchParts = 'nested';
+  const state = new smartstate.Smartstate<TBatchParts>();
+  const part = await state.getStatePart<ITestState>('nested', {
+    value: 0,
+    nested: { data: 'start' }
+  });
+
+  const values: number[] = [];
+  part.select((s) => s.value).subscribe((v) => values.push(v));
+  values.length = 0;
+
+  await state.batch(async () => {
+    await part.setState({ value: 1, nested: { data: 'a' } });
+
+    await state.batch(async () => {
+      await part.setState({ value: 2, nested: { data: 'b' } });
+      // Still inside outer batch
+      expect(values).toHaveLength(0);
+    });
+
+    // Inner batch ended but outer batch still active
+    expect(values).toHaveLength(0);
+  });
+
+  // Now outer batch is done — should see final notification
+  expect(values.length).toBeGreaterThanOrEqual(1);
+  expect(values[values.length - 1]).toEqual(2);
+});
+
+// ============================
+// Computed state tests
+// ============================
+
+tap.test('computed should derive from multiple state parts', async () => {
+  type TComputedParts = 'first' | 'second';
+  const state = new smartstate.Smartstate<TComputedParts>();
+  const first = await state.getStatePart<{ count: number }>('first', { count: 5 });
+  const second = await state.getStatePart<{ count: number }>('second', { count: 10 });
+
+  const derived$ = state.computed(
+    [first, second],
+    (a, b) => a.count + b.count,
+  );
+
+  const values: number[] = [];
+  derived$.subscribe((v) => values.push(v));
+
+  expect(values).toContain(15);
+});
+
+tap.test('computed should update when a source changes', async () => {
+  type TComputedParts = 'x' | 'y';
+  const state = new smartstate.Smartstate<TComputedParts>();
+  const x = await state.getStatePart<{ n: number }>('x', { n: 1 });
+  const y = await state.getStatePart<{ n: number }>('y', { n: 2 });
+
+  const derived$ = state.computed(
+    [x, y],
+    (xState, yState) => xState.n * yState.n,
+  );
+
+  const values: number[] = [];
+  derived$.subscribe((v) => values.push(v));
+
+  // Initial: 1 * 2 = 2
+  expect(values[0]).toEqual(2);
+
+  await x.setState({ n: 5 });
+
+  // After update: 5 * 2 = 10
+  expect(values[values.length - 1]).toEqual(10);
+});
+
+tap.test('standalone computed function should work', async () => {
+  type TParts = 'a' | 'b';
+  const state = new smartstate.Smartstate<TParts>();
+  const a = await state.getStatePart<{ val: string }>('a', { val: 'hello' });
+  const b = await state.getStatePart<{ val: string }>('b', { val: 'world' });
+
+  const derived$ = smartstate.computed(
+    [a, b],
+    (aState, bState) => `${aState.val} ${bState.val}`,
+  );
+
+  const values: string[] = [];
+  derived$.subscribe((v) => values.push(v));
+
+  expect(values[0]).toEqual('hello world');
+
+  await a.setState({ val: 'hi' });
+  expect(values[values.length - 1]).toEqual('hi world');
+});
+
+// ============================
+// Context Protocol tests
+// ============================
+
+tap.test('attachContextProvider should respond to context-request events', async () => {
+  // EventTarget and CustomEvent are available in Node 18+
+  if (typeof EventTarget === 'undefined') {
+    console.log('Skipping context test — EventTarget not available');
+    return;
+  }
+
+  type TParts = 'ctx';
+  const state = new smartstate.Smartstate<TParts>();
+  const statePart = await state.getStatePart<{ theme: string }>('ctx', { theme: 'dark' });
+
+  const myContext = Symbol('test-context');
+
+  // Use an EventTarget as a mock element
+  const element = new EventTarget() as any as HTMLElement;
+
+  const cleanup = smartstate.attachContextProvider(element, {
+    context: myContext,
+    statePart,
+  });
+
+  let receivedValue: any = null;
+
+  // Dispatch a context-request event
+  const event = new CustomEvent('context-request', {
+    detail: {
+      context: myContext,
+      callback: (value: any) => { receivedValue = value; },
+      subscribe: false,
+    },
+    bubbles: true,
+    composed: true,
+  });
+  (element as any).dispatchEvent(event);
+
+  expect(receivedValue).toEqual({ theme: 'dark' });
+
+  cleanup();
+});
+
+tap.test('attachContextProvider should support subscriptions', async () => {
+  if (typeof EventTarget === 'undefined') {
+    console.log('Skipping context subscription test — EventTarget not available');
+    return;
+  }
+
+  type TParts = 'ctxSub';
+  const state = new smartstate.Smartstate<TParts>();
+  const statePart = await state.getStatePart<{ count: number }>('ctxSub', { count: 0 });
+
+  const myContext = Symbol('sub-context');
+  const element = new EventTarget() as any as HTMLElement;
+
+  const cleanup = smartstate.attachContextProvider(element, {
+    context: myContext,
+    statePart,
+  });
+
+  const receivedValues: any[] = [];
+  let unsubFn: (() => void) | undefined;
+
+  const event = new CustomEvent('context-request', {
+    detail: {
+      context: myContext,
+      callback: (value: any, unsub?: () => void) => {
+        receivedValues.push(value);
+        if (unsub) unsubFn = unsub;
+      },
+      subscribe: true,
+    },
+    bubbles: true,
+    composed: true,
+  });
+  (element as any).dispatchEvent(event);
+
+  expect(receivedValues).toHaveLength(1);
+  expect(receivedValues[0]).toEqual({ count: 0 });
+
+  // Update state — should trigger subscription callback
+  await statePart.setState({ count: 42 });
+
+  // Give a tick for the subscription to fire
+  await new Promise<void>((r) => setTimeout(r, 10));
+
+  expect(receivedValues.length).toBeGreaterThanOrEqual(2);
+  expect(receivedValues[receivedValues.length - 1]).toEqual({ count: 42 });
+
+  // Unsubscribe
+  expect(unsubFn).toBeDefined();
+  unsubFn!();
+
+  cleanup();
+});
+
+tap.test('attachContextProvider should ignore non-matching contexts', async () => {
+  if (typeof EventTarget === 'undefined') {
+    console.log('Skipping context mismatch test — EventTarget not available');
+    return;
+  }
+
+  type TParts = 'ctxMismatch';
+  const state = new smartstate.Smartstate<TParts>();
+  const statePart = await state.getStatePart<{ v: number }>('ctxMismatch', { v: 1 });
+
+  const myContext = Symbol('my-context');
+  const otherContext = Symbol('other-context');
+  const element = new EventTarget() as any as HTMLElement;
+
+  const cleanup = smartstate.attachContextProvider(element, {
+    context: myContext,
+    statePart,
+  });
+
+  let called = false;
+  const event = new CustomEvent('context-request', {
+    detail: {
+      context: otherContext,
+      callback: () => { called = true; },
+      subscribe: false,
+    },
+    bubbles: true,
+    composed: true,
+  });
+  (element as any).dispatchEvent(event);
+
+  expect(called).toBeFalse();
+
+  cleanup();
+});
+
 export default tap.start();

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartstate',
-  version: '2.0.31',
+  version: '2.1.0',
-  description: 'A package for handling and managing state in applications.'
+  description: 'A TypeScript-first reactive state management library with middleware, computed state, batching, persistence, and Web Component Context Protocol support.'
 }

ts/index.ts

@@ -1,3 +1,5 @@
 export * from './smartstate.classes.smartstate.js';
 export * from './smartstate.classes.statepart.js';
 export * from './smartstate.classes.stateaction.js';
+export * from './smartstate.classes.computed.js';
+export * from './smartstate.contextprovider.js';

ts/smartstate.classes.computed.ts

@@ -0,0 +1,16 @@
+import * as plugins from './smartstate.plugins.js';
+import { combineLatest, map } from 'rxjs';
+import type { StatePart } from './smartstate.classes.statepart.js';
+
+/**
+ * creates a computed observable derived from multiple state parts.
+ * the observable is lazy — it only subscribes to sources when subscribed to.
+ */
+export function computed<TResult>(
+  sources: StatePart<any, any>[],
+  computeFn: (...states: any[]) => TResult,
+): plugins.smartrx.rxjs.Observable<TResult> {
+  return combineLatest(sources.map((sp) => sp.select())).pipe(
+    map((states) => computeFn(...states)),
+  ) as plugins.smartrx.rxjs.Observable<TResult>;
+}

ts/smartstate.classes.smartstate.ts

@@ -1,5 +1,6 @@
 import * as plugins from './smartstate.plugins.js';
 import { StatePart } from './smartstate.classes.statepart.js';
+import { computed } from './smartstate.classes.computed.js';
 
 export type TInitMode = 'soft' | 'mandatory' | 'force' | 'persistent';
 
@@ -11,17 +12,57 @@ export class Smartstate<StatePartNameType extends string> {
 
   private pendingStatePartCreation: Map<string, Promise<StatePart<StatePartNameType, any>>> = new Map();
 
+  // Batch support
+  private batchDepth = 0;
+  private pendingNotifications = new Set<StatePart<any, any>>();
+
   constructor() {}
 
+  /**
+   * whether state changes are currently being batched
+   */
+  public get isBatching(): boolean {
+    return this.batchDepth > 0;
+  }
+
+  /**
+   * registers a state part for deferred notification during a batch
+   */
+  public registerPendingNotification(statePart: StatePart<any, any>): void {
+    this.pendingNotifications.add(statePart);
+  }
+
+  /**
+   * batches multiple state updates so subscribers are only notified once all updates complete
+   */
+  public async batch(updateFn: () => Promise<void> | void): Promise<void> {
+    this.batchDepth++;
+    try {
+      await updateFn();
+    } finally {
+      this.batchDepth--;
+      if (this.batchDepth === 0) {
+        const pending = [...this.pendingNotifications];
+        this.pendingNotifications.clear();
+        for (const sp of pending) {
+          await sp.notifyChange();
+        }
+      }
+    }
+  }
+
+  /**
+   * creates a computed observable derived from multiple state parts
+   */
+  public computed<TResult>(
+    sources: StatePart<StatePartNameType, any>[],
+    computeFn: (...states: any[]) => TResult,
+  ): plugins.smartrx.rxjs.Observable<TResult> {
+    return computed(sources, computeFn);
+  }
+
   /**
    * Allows getting and initializing a new statepart
-   * initMode === 'soft' (default) - returns existing statepart if exists, creates new if not
-   * initMode === 'mandatory' - requires statepart to not exist, fails if it does
-   * initMode === 'force' - always creates new statepart, overwriting any existing
-   * initMode === 'persistent' - like 'soft' but with webstore persistence
-   * @param statePartNameArg
-   * @param initialArg
-   * @param initMode
    */
   public async getStatePart<PayloadType>(
     statePartNameArg: StatePartNameType,
@@ -43,16 +84,13 @@ export class Smartstate<StatePartNameType extends string> {
             `State part '${statePartNameArg}' already exists, but initMode is 'mandatory'`
           );
         case 'force':
-          // Force mode: create new state part
+          break;
-          break; // Fall through to creation
         case 'soft':
         case 'persistent':
         default:
-          // Return existing state part
           return existingStatePart as StatePart<StatePartNameType, PayloadType>;
       }
     } else {
-      // State part doesn't exist
       if (!initialArg) {
         throw new Error(
           `State part '${statePartNameArg}' does not exist and no initial state provided`
@@ -73,9 +111,6 @@ export class Smartstate<StatePartNameType extends string> {
 
   /**
    * Creates a statepart
-   * @param statePartName
-   * @param initialPayloadArg
-   * @param initMode
    */
   private async createStatePart<PayloadType>(
     statePartName: StatePartNameType,
@@ -91,17 +126,16 @@ export class Smartstate<StatePartNameType extends string> {
           }
         : null
     );
+    newState.smartstateRef = this;
     await newState.init();
     const currentState = newState.getState();
 
     if (initMode === 'persistent' && currentState !== undefined) {
-      // Persisted state exists - merge with defaults, persisted values take precedence
       await newState.setState({
         ...initialPayloadArg,
         ...currentState,
       });
     } else {
-      // No persisted state or non-persistent mode
       await newState.setState(initialPayloadArg);
     }
 

ts/smartstate.classes.statepart.ts

@@ -1,21 +1,54 @@
 import * as plugins from './smartstate.plugins.js';
+import { Observable, shareReplay, takeUntil } from 'rxjs';
 import { StateAction, type IActionDef } from './smartstate.classes.stateaction.js';
+import type { Smartstate } from './smartstate.classes.smartstate.js';
+
+export type TMiddleware<TPayload> = (
+  newState: TPayload,
+  oldState: TPayload | undefined,
+) => TPayload | Promise<TPayload>;
+
+/**
+ * creates an Observable that emits once when the given AbortSignal fires
+ */
+function fromAbortSignal(signal: AbortSignal): Observable<void> {
+  return new Observable<void>((subscriber) => {
+    if (signal.aborted) {
+      subscriber.next();
+      subscriber.complete();
+      return;
+    }
+    const handler = () => {
+      subscriber.next();
+      subscriber.complete();
+    };
+    signal.addEventListener('abort', handler);
+    return () => signal.removeEventListener('abort', handler);
+  });
+}
 
 export class StatePart<TStatePartName, TStatePayload> {
   public name: TStatePartName;
   public state = new plugins.smartrx.rxjs.Subject<TStatePayload>();
   public stateStore: TStatePayload | undefined;
+  public smartstateRef?: Smartstate<any>;
   private cumulativeDeferred = plugins.smartpromise.cumulativeDefer();
 
   private pendingCumulativeNotification: ReturnType<typeof setTimeout> | null = null;
+  private pendingBatchNotification = false;
 
   private webStoreOptions: plugins.webstore.IWebStoreOptions;
-  private webStore: plugins.webstore.WebStore<TStatePayload> | null = null; // Add WebStore instance
+  private webStore: plugins.webstore.WebStore<TStatePayload> | null = null;
+
+  private middlewares: TMiddleware<TStatePayload>[] = [];
+
+  // Selector memoization
+  private selectorCache = new WeakMap<Function, plugins.smartrx.rxjs.Observable<any>>();
+  private defaultSelectObservable: plugins.smartrx.rxjs.Observable<TStatePayload> | null = null;
 
   constructor(nameArg: TStatePartName, webStoreOptionsArg?: plugins.webstore.IWebStoreOptions) {
     this.name = nameArg;
 
-    // Initialize WebStore if webStoreOptions are provided
     if (webStoreOptionsArg) {
       this.webStoreOptions = webStoreOptionsArg;
     }
@@ -43,23 +76,43 @@ export class StatePart<TStatePartName, TStatePayload> {
     return this.stateStore;
   }
 
+  /**
+   * adds a middleware that intercepts setState calls.
+   * middleware can transform the state or throw to reject it.
+   * returns a removal function.
+   */
+  public addMiddleware(middleware: TMiddleware<TStatePayload>): () => void {
+    this.middlewares.push(middleware);
+    return () => {
+      const idx = this.middlewares.indexOf(middleware);
+      if (idx !== -1) {
+        this.middlewares.splice(idx, 1);
+      }
+    };
+  }
+
   /**
    * sets the stateStore to the new state
-   * @param newStateArg
    */
   public async setState(newStateArg: TStatePayload) {
+    // Run middleware chain
+    let processedState = newStateArg;
+    for (const mw of this.middlewares) {
+      processedState = await mw(processedState, this.stateStore);
+    }
+
     // Validate state structure
-    if (!this.validateState(newStateArg)) {
+    if (!this.validateState(processedState)) {
       throw new Error(`Invalid state structure for state part '${this.name}'`);
     }
 
-    // Save to WebStore first to ensure atomicity - if save fails, memory state remains unchanged
+    // Save to WebStore first to ensure atomicity
     if (this.webStore) {
-      await this.webStore.set(String(this.name), newStateArg);
+      await this.webStore.set(String(this.name), processedState);
     }
 
     // Update in-memory state after successful persistence
-    this.stateStore = newStateArg;
+    this.stateStore = processedState;
     await this.notifyChange();
 
     return this.stateStore;
@@ -67,11 +120,8 @@ export class StatePart<TStatePartName, TStatePayload> {
 
   /**
    * Validates state structure - can be overridden for custom validation
-   * @param stateArg
    */
   protected validateState(stateArg: any): stateArg is TStatePayload {
-    // Basic validation - ensure state is not null/undefined
-    // Subclasses can override for more specific validation
     return stateArg !== null && stateArg !== undefined;
   }
 
@@ -82,6 +132,14 @@ export class StatePart<TStatePartName, TStatePayload> {
     if (!this.stateStore) {
       return;
     }
+
+    // If inside a batch, defer the notification
+    if (this.smartstateRef?.isBatching) {
+      this.pendingBatchNotification = true;
+      this.smartstateRef.registerPendingNotification(this);
+      return;
+    }
+
     const createStateHash = async (stateArg: any) => {
       return await plugins.smarthashWeb.sha256FromString(plugins.smartjson.stableOneWayStringify(stateArg));
     };
@@ -99,10 +157,9 @@ export class StatePart<TStatePartName, TStatePayload> {
   private lastStateNotificationPayloadHash: any;
 
   /**
-   * creates a cumulative notification by adding a change notification at the end of the call stack;
+   * creates a cumulative notification by adding a change notification at the end of the call stack
    */
   public notifyChangeCumulative() {
-    // Debounce: clear any pending notification
     if (this.pendingCumulativeNotification) {
       clearTimeout(this.pendingCumulativeNotification);
     }
@@ -116,27 +173,56 @@ export class StatePart<TStatePartName, TStatePayload> {
   }
 
   /**
-   * selects a state or a substate
+   * selects a state or a substate.
+   * supports an optional AbortSignal for automatic unsubscription.
+   * memoizes observables by selector function reference.
    */
   public select<T = TStatePayload>(
-    selectorFn?: (state: TStatePayload) => T
+    selectorFn?: (state: TStatePayload) => T,
+    options?: { signal?: AbortSignal }
   ): plugins.smartrx.rxjs.Observable<T> {
-    if (!selectorFn) {
+    const hasSignal = options?.signal != null;
-      selectorFn = (state: TStatePayload) => <T>(<any>state);
+
+    // Check memoization cache (only for non-signal selects)
+    if (!hasSignal) {
+      if (!selectorFn) {
+        if (this.defaultSelectObservable) {
+          return this.defaultSelectObservable as unknown as plugins.smartrx.rxjs.Observable<T>;
+        }
+      } else if (this.selectorCache.has(selectorFn)) {
+        return this.selectorCache.get(selectorFn)!;
+      }
     }
-    const mapped = this.state.pipe(
+
+    const effectiveSelectorFn = selectorFn || ((state: TStatePayload) => <T>(<any>state));
+
+    let mapped = this.state.pipe(
       plugins.smartrx.rxjs.ops.startWith(this.getState()),
       plugins.smartrx.rxjs.ops.filter((stateArg): stateArg is TStatePayload => stateArg !== undefined),
       plugins.smartrx.rxjs.ops.map((stateArg) => {
         try {
-          return selectorFn(stateArg);
+          return effectiveSelectorFn(stateArg);
         } catch (e) {
           console.error(`Selector error in state part '${this.name}':`, e);
           return undefined;
         }
       })
     );
-    return mapped;
+
+    if (hasSignal) {
+      mapped = mapped.pipe(takeUntil(fromAbortSignal(options.signal)));
+      return mapped;
+    }
+
+    // Apply shareReplay for caching and store in memo cache
+    const shared = mapped.pipe(shareReplay({ bufferSize: 1, refCount: true }));
+    if (!selectorFn) {
+      this.defaultSelectObservable = shared as unknown as plugins.smartrx.rxjs.Observable<TStatePayload>;
+    } else {
+      this.selectorCache.set(selectorFn, shared);
+    }
+
+    return shared;
   }
 
   /**
@@ -159,18 +245,32 @@ export class StatePart<TStatePartName, TStatePayload> {
   }
 
   /**
-   * waits until a certain part of the state becomes available
+   * waits until a certain part of the state becomes available.
-   * @param selectorFn
+   * supports optional timeout and AbortSignal.
-   * @param timeoutMs - optional timeout in milliseconds to prevent indefinite waiting
    */
   public async waitUntilPresent<T = TStatePayload>(
     selectorFn?: (state: TStatePayload) => T,
-    timeoutMs?: number
+    optionsOrTimeout?: number | { timeoutMs?: number; signal?: AbortSignal }
   ): Promise<T> {
+    // Parse backward-compatible args
+    let timeoutMs: number | undefined;
+    let signal: AbortSignal | undefined;
+    if (typeof optionsOrTimeout === 'number') {
+      timeoutMs = optionsOrTimeout;
+    } else if (optionsOrTimeout) {
+      timeoutMs = optionsOrTimeout.timeoutMs;
+      signal = optionsOrTimeout.signal;
+    }
+
     const done = plugins.smartpromise.defer<T>();
     const selectedObservable = this.select(selectorFn);
     let resolved = false;
 
+    // Check if already aborted
+    if (signal?.aborted) {
+      throw new Error('Aborted');
+    }
+
     const subscription = selectedObservable.subscribe((value) => {
       if (value && !resolved) {
         resolved = true;
@@ -189,12 +289,29 @@ export class StatePart<TStatePartName, TStatePayload> {
       }, timeoutMs);
     }
 
+    // Handle abort signal
+    const abortHandler = signal ? () => {
+      if (!resolved) {
+        resolved = true;
+        subscription.unsubscribe();
+        if (timeoutId) clearTimeout(timeoutId);
+        done.reject(new Error('Aborted'));
+      }
+    } : undefined;
+
+    if (signal && abortHandler) {
+      signal.addEventListener('abort', abortHandler);
+    }
+
     try {
       const result = await done.promise;
       return result;
     } finally {
       subscription.unsubscribe();
       if (timeoutId) clearTimeout(timeoutId);
+      if (signal && abortHandler) {
+        signal.removeEventListener('abort', abortHandler);
+      }
     }
   }
 

ts/smartstate.contextprovider.ts

@@ -0,0 +1,61 @@
+import type { StatePart } from './smartstate.classes.statepart.js';
+
+export interface IContextProviderOptions<TPayload> {
+  /** the context key (compared by strict equality) */
+  context: unknown;
+  /** the state part to provide */
+  statePart: StatePart<any, TPayload>;
+  /** optional selector to provide a derived value instead of the full state */
+  selectorFn?: (state: TPayload) => any;
+}
+
+/**
+ * attaches a Context Protocol provider to an HTML element.
+ * listens for `context-request` events and responds with the state part's value.
+ * if subscribe=true, retains the callback and invokes it on every state change.
+ * returns a cleanup function that removes the listener and unsubscribes.
+ */
+export function attachContextProvider<TPayload>(
+  element: HTMLElement,
+  options: IContextProviderOptions<TPayload>,
+): () => void {
+  const { context, statePart, selectorFn } = options;
+  const subscribers = new Set<(value: any, unsubscribe?: () => void) => void>();
+
+  const subscription = statePart.select(selectorFn).subscribe((value) => {
+    for (const cb of subscribers) {
+      cb(value);
+    }
+  });
+
+  const getValue = (): any => {
+    const state = statePart.getState();
+    if (state === undefined) return undefined;
+    return selectorFn ? selectorFn(state) : state;
+  };
+
+  const handler = (event: Event) => {
+    const e = event as CustomEvent;
+    const detail = e.detail;
+    if (!detail || detail.context !== context) return;
+
+    e.stopPropagation();
+
+    if (detail.subscribe) {
+      const cb = detail.callback;
+      subscribers.add(cb);
+      const unsubscribe = () => subscribers.delete(cb);
+      cb(getValue(), unsubscribe);
+    } else {
+      detail.callback(getValue());
+    }
+  };
+
+  element.addEventListener('context-request', handler);
+
+  return () => {
+    element.removeEventListener('context-request', handler);
+    subscription.unsubscribe();
+    subscribers.clear();
+  };
+}