Cogsbox State

🚨 DANGER: DO NOT USE - UNSTABLE & EXPERIMENTAL 🚨

This library is in early development and constantly changing.

DO NOT USE IN ANY PROJECT YET - ONLY FOR TESTING AND PROVIDING FEEDBACK.

What is Cogsbox State?

Cogsbox State is a React state management library that creates a nested state builder - a type-safe proxy that mimics your initial state structure. Every property in your state becomes a powerful state object with built-in methods for updates, arrays, forms, and more.

Key Philosophy: Instead of complex useState drilling and manual mapping, you directly access nested properties and use built-in methods.

Getting Started

Basic Setup

import { createCogsState } from 'cogsbox-state';

type Todo = {
  id: number;
  text: string;
  done: boolean;
}

type AppState = {
  user: {
    name: string;
    stats: {
      counter: number;
      lastUpdated: number | null; // Be specific with types
    },
    age: number;
    online: boolean;
  };
  todos: Todo[]; // Use the interface here
  settings: {
    darkMode: boolean;
    notifications: boolean;
  }
}
// 1. Define your initial state structure
const initialState: AppState = {
  user: {
    name: "John",
    stats: {
      counter: 0,
      lastUpdated: null
    },
    age: 30,
    online:false
  },
  todos: [],
  settings: {
    darkMode: false,
    notifications: true
  }
};

// 2. Create your state manager
const { useCogsState } = createCogsState(initialState);

// 3. Use in components - access specific state slices by their keys
function UserComponent() {
  const user = useCogsState('user'); // Access the 'user' slice

  return (
    <div>
      <p>Name: {user.name.$get()}</p>
      <p>Counter: {user.stats.counter.$get()}</p>
      <button onClick={() => user.stats.counter.$update(prev => prev + 1)}>
        Increment Counter
      </button>
    </div>
  );
}

function TodoComponent() {
  const todos = useCogsState('todos'); // Access the 'todos' slice

  return (
    <div>
      <p>Todo count: {todos.$get().length}</p>
      <button onClick={() => todos.$insert({ id: Date.now(), text: 'New todo', done: false })}>
        Add Todo
      </button>
    </div>
  );
}

Core Concepts

State Access Patterns

Every state property gets these core methods:

Primitives (strings, numbers, booleans)

• .$get() - read values reactively
• .$update() - set values
• .$toggle() - flip booleans
• .$$get() - non-reactive read (signals)
• .$$derive() - computed signals

Objects

• All primitive methods plus access to nested properties
• .$update() can do partial updates

Arrays

• All core methods plus array-specific operations
• Built-in selection tracking and metadata

Reading State

const user = useCogsState('user');
const todos = useCogsState('todos');
const settings = useCogsState('settings');

// Reactive reads (triggers re-renders)
const userName = user.name.$get();
const allTodos = todos.$get();
const isDarkMode = settings.darkMode.$get();

// Access nested properties
const counterValue = user.stats.counter.$get();
const firstTodo = todos.$index(0)?.$get();

// Non-reactive reads (no re-renders, for signals)
const userNameStatic = user.name.$$get();

// Computed signals (transforms value without re-renders)
const todoCount = todos.$$derive((todos) => todos.length);

Updating State

const user = useCogsState('user');
const settings = useCogsState('settings');
const todos = useCogsState('todos');

// Direct updates
user.name.$update('Jane');
settings.darkMode.$toggle();

// Functional updates
user.stats.counter.$update((prev) => prev + 1);

// Object updates
user.$update((prev) => ({ ...prev, name: 'Jane', age: 30 }));

// Deep nested updates
todos.$index(0).text.$update('Updated todo text');

Working with Arrays

Arrays are first-class citizens with powerful built-in operations:

Basic Array Operations

const todos = useCogsState('todos');

// Add items
todos.$insert({ id: 'uuid', text: 'New todo', done: false });
todos.$insert(({ uuid }) => ({
  id: uuid,
  text: 'Auto-generated ID',
  done: false,
}));

// Remove items
todos.$cut(2); // Remove at index 2
todos.$cutSelected(); // Remove currently selected item

// Access items
const firstTodo = todos.$index(0);
const lastTodo = todos.$last();

Array Iteration and Rendering

$map() - Enhanced Array Mapping

const todos = useCogsState('todos');

// Returns transformed array, each item is a full state object
const todoElements = todos.$map((todoState, index, arrayState) => (
  <TodoItem
    key={todoState.id.$get()}
    todo={todoState}
    onToggle={() => todoState.done.$toggle()}
    onDelete={() => arrayState.$cut(index)}
  />
));

$list() - JSX List Rendering

const todos = useCogsState('todos');

// Renders directly in place with automatic key management
{todos.$list((todoState, index, arrayState) => (
  <div key={todoState.id.$get()}>
    <span>{todoState.text.$get()}</span>
    <button onClick={() => todoState.done.$toggle()}>Toggle</button>
    <button onClick={() => arrayState.$cut(index)}>Delete</button>
  </div>
))}

Advanced Array Methods

Filtering and Sorting

const todos = useCogsState('todos');

// Filter items (returns new state object with filtered view)
const completedTodos = todos.$filter((todo) => todo.done);
const incompleteTodos = todos.$filter((todo) => !todo.done);

// Sort items (returns new state object with sorted view)
const sortedTodos = todos.$sort((a, b) => a.text.localeCompare(b.text));

// Chain operations
const sortedCompletedTodos = todos
  .$filter((todo) => todo.done)
  .$sort((a, b) => new Date(a.createdAt) - new Date(b.createdAt));

Finding and Searching

const todos = useCogsState('todos');

// Find by property value
const todoById = todos.$findWith('id', 'some-id');
if (todoById) {
  todoById.text.$update('Updated text');
}

// Find with custom function
const firstIncompleteTodo = todos.$find((todo) => !todo.done);

Unique Operations

const todos = useCogsState('todos');

// Insert only if unique (prevents duplicates)
todos.$uniqueInsert(
  { id: 'new-id', text: 'New todo', done: false },
  ['id'], // Fields to check for uniqueness
  (existingItem) => {
    // Optional: callback if match found
    return { ...existingItem, text: 'Updated existing' };
  }
);

Selection Management

const todos = useCogsState('todos');

// Built-in selection tracking
const selectedTodo = todos.$getSelected();
const selectedIndex = todos.$getSelectedIndex();

// Set selection on individual items
todos.$index(0).$setSelected(true);
todos.$index(0).$toggleSelected();

// Clear all selections
todos.$clearSelected();

// Check if item is selected
const isSelected = todos.$index(0).isSelected;

Plugin Chain Methods

For a full plugin how-to (registration, hooks, validation, etc.) see PLUGINS.md.

Plugins can add custom methods to the state builder chain with .methods(...). This is useful for reusable behaviours such as uploads, persistence, analytics, or domain-specific state actions.

import { createCogsState, createPluginContext } from 'cogsbox-state';
import { z } from 'zod';

const { createPlugin } = createPluginContext({
  options: z.object({
    bucketPrefix: z.string().optional(),
  }),
});

const s3Plugin = createPlugin('s3').methods(({ path, array }) => ({
  sendToS3: path((state) => state.users.$.profile.image)(
    async (ctx, bucket: string) => {
      return upload(ctx.$get(), bucket);
    }
  ),

  sendManyToS3: array(async (ctx, bucket: string) => {
    return uploadMany(ctx.$get(), bucket);
  }),

  sendGalleryToS3: path((state) => state.galleries.$.images).array(
    async (ctx, bucket: string) => {
      return uploadMany(ctx.$get(), bucket, ctx.options?.bucketPrefix);
    }
  ),
}));

const { useCogsState } = createCogsState(initialState, {
  plugins: [s3Plugin],
});

Use the plugin by passing its options to useCogsState:

const assets = useCogsState('assets', {
  s3: { bucketPrefix: 'uploads' },
});

await assets.users.$index(0).profile.image.$sendToS3('avatars');
await assets.galleries.$index(0).images.$sendGalleryToS3('gallery');
await assets.looseImages.$sendManyToS3('images');

Method Targets

Method helpers decide where a method can run:

• field(fn) - any state node
• array(fn) - arrays only
• object(fn) - plain objects only
• primitive(fn) - strings, numbers, booleans, null, etc.
• boolean(fn) - booleans only
• path(selector)(fn) - only a matching path
• path(selector).array(fn) - matching path and array value

The path helper receives a path-recorder proxy. The $ segment means "one path segment", which naturally matches array item ids internally:

path((state) => state.users.$.profile.image);

matches calls like:

assets.users.$index(0).profile.image.$sendToS3('avatars');

The first handler argument is a scoped plugin context. The remaining handler arguments become the chain method arguments, and the return type is preserved:

const imagePlugin = createPlugin('images').methods(({ field }) => ({
  resize: field((ctx, width: number, height: number) => {
    return resizeImage(ctx.$get(), width, height);
  }),
}));

// typed as resize(width: number, height: number): ReturnType<typeof resizeImage>
state.avatar.resize(200, 200);

If a real state field has the same name as a plugin method, the state field wins.

Reactivity Control

Cogsbox offers different reactivity modes for performance optimization:

Component Reactivity (Default)

// Re-renders when any accessed state changes
const user = useCogsState('user');
// or explicitly:
const user = useCogsState('user', { reactiveType: 'component' });

Dependency-Based Reactivity

// Only re-renders when specified dependencies change
const user = useCogsState('user', {
  reactiveType: 'deps',
  reactiveDeps: (state) => [state.name, state.stats.counter],
});

Full Reactivity

// Re-renders on ANY change to the state slice
const user = useCogsState('user', { reactiveType: 'all' });

No Reactivity

// Never re-renders (useful with signals)
const todos = useCogsState('todos', { reactiveType: 'none' });

Multiple Reactivity Types

// Combine multiple reactivity modes
const user = useCogsState('user', {
  reactiveType: ['component', 'deps'],
  reactiveDeps: (state) => [state.online],
});

Form Management

Cogsbox excels at form handling with automatic debouncing and validation:

Basic Form Elements

import { createCogsState } from 'cogsbox-state';
import { z } from 'zod';

// 1. Define the validation schema. This is your single source of truth.
const userSchema = z.object({
  name: z.string().min(1, "Name is required"),
  email: z.string().email("Invalid email"),
  age: z.number().min(18, "Must be 18+")
});

// 2. Best Practice: Infer the TypeScript type directly from the schema.
type UserFormData = z.infer<typeof userSchema>;

// 3. Define the initial state for the form using the inferred type.
const initialUserFormState: UserFormData = {
  name: "",
  email: "",
  age: 18
};

// 4. Create the state manager.
const { useCogsState } = createCogsState({
  userForm: {
    initialState: initialUserFormState,
    validation: {
      key: "userValidation",
      zodSchemaV4: userSchema, // Pass the schema for runtime validation
      onBlur: 'error'
    },
    formElements: {
      validation: ({ children, hasErrors, message }) => (
        <div className="form-field">
          {children}
          {hasErrors && <span className="error">{message}</span>}
        </div>
      )
    }
  }
});

function UserForm() {
  const userForm = useCogsState('userForm');

  return (
    <form>
      {/* Auto-debounced input with validation wrapper */}
      {userForm.name.$formElement(({ $inputProps }) => (
        <>
          <label>Name</label>
          <input {...$inputProps} />
        </>
      ))}

      {/* Custom debounce time */}
      {userForm.email.$formElement(({ $inputProps }) => (
        <>
          <label>Email</label>
          <input {...$inputProps} />
        </>
      ), { debounceTime: 500 })}

      {/* Custom form control */}
      {userForm.age.$formElement(({ $get, $update }) => (
        <>
          <label>Age</label>
          <input
            type="number"
            value={$get()}
            onChange={e => $update(parseInt(e.target.value))}
          />
        </>
      ))}
    </form>
  );
}

Reading Validation State

Use $validationErrors() on an object state node to get validation summaries for its immediate child fields.

const userForm = useCogsState('userForm');

const validation = userForm.$validationErrors();

This returns an array of objects. Each item includes the field path plus the current validation state for that path:

[
  {
    path: ['name'],
    status: 'INVALID',
    severity: 'error',
    hasErrors: true,
    hasWarnings: false,
    message: 'Name is required',
    errors: ['Name is required'],
    warnings: [],
    allErrors: [
      {
        path: ['name'],
        source: 'client',
        severity: 'error',
        message: 'Name is required',
        code: 'too_small',
      },
    ],
    getData: () => '',
  },
]

Pass a type-safe string array to read only specific fields. This is useful for multi-stage forms where a stage should not advance while selected fields have errors.

const stageValidation = userForm.$validationErrors([
  'name',
  'email',
]);

if (stageValidation.some((field) => field.hasErrors)) {
  return;
}

goToNextStage();

The keys must exist on the object state node, so this is checked by TypeScript:

userForm.$validationErrors(['name']); // ok
userForm.$validationErrors(['missingField']); // type error