### Initial Cells Configuration Examples

Source: https://gridsheet.walkframe.com/api-reference/props

Examples demonstrating how to configure the `initialCells` prop, including setting default styles, column/row dimensions, and individual cell data.

```APIDOC
## Initial Cells Configuration

### Default Configuration
The `default` key applies a base configuration to all cells in the spreadsheet, which is useful for setting global shared styles. However, **`width` and `height` cannot be set via `default`**.

To set a global default width or height that applies to all headers, use the `defaultCol` and `defaultRow` keys instead:

```javascript
const initialCells = {
  // Applies to all cells in the sheet
  default: { 
    style: { fontSize: '14px' }
  },
  // Base configuration for all column headers
  defaultCol: {
    width: 100
  },
  // Base configuration for all row headers
  defaultRow: {
    height: 30
  },
  'A1': { value: 'Hello World' },
  'B2': { value: 100 },
};
```

### Header Configuration
Header dimensions are configured using the `0` key for the corner cell (sets default header height/width):

```javascript
const initialCells = {
  // Corner cell: default header row height and column header width
  '0': {
    height: 60,  // Header row height
    width: 80,   // Row header width
  },
  'A1': { value: 'Hello World' },
};
```

### Header Cell Addressing (`ch()`, `rh()`, `A0:G0`)
To configure individual column or row header cells, you should use the `ch()` and `rh()` utility functions provided by `@gridsheet/react-core`. While internally GridSheet appends a `0` (e.g., `A0`, `01`), Using the `ch` and `rh` functions is strongly recommended.

* **`ch('A')`** (evaluates to `A0`) — Column A's header cell only (width, label, style, etc.)
* **`rh(1)`** (evaluates to `01`) — Row 1's header cell only (height, style, etc.)
* **`A0:G0`** — Range of column header cells (A through G)

```javascript
import { ch, rh } from '@gridsheet/react-core';
 
const initialCells = {
  // Column A header: set width and label
  [ch('A')]: { width: 150, label: 'Product' },
  // Row 1 header: set height
  [rh(1)]: { height: 50 },
  // Style column headers F and G blue
  'F0:G0': { style: { color: 'blue' } },
  // All data cells in column A (does NOT affect the header)
  A: { style: { backgroundColor: '#eef' } },
};
```

**Note**: `A: { ... }` applies to **all data cells** in column A (rows 1 and below). Use `ch('A')` to target the column A header cell. Similarly, `1: { ... }` applies to all data cells in row 1; use `rh(1)` for the row 1 header.

### Column and Row Specifications
For columns and rows, you can specify using only one side of the address:

* **Columns**: Use just the column letter (e.g., `D` for column D)
* **Rows**: Use just the row number (e.g., `3` for row 3)

```

--------------------------------

### Clone Repository and Install Dependencies

Source: https://gridsheet.walkframe.com/development/development-guide

Clone the GridSheet repository and install project dependencies using pnpm.

```bash
git clone https://github.com/your-org/gridsheet.git
cd gridsheet

pnpm install
```

--------------------------------

### Start Storybook Server

Source: https://gridsheet.walkframe.com/development/development-guide

Launch the Storybook development server with `pnpm dev` to view and interact with UI components.

```bash
# Start Storybook development server
pnpm dev
```

--------------------------------

### Install GridSheet React Core and Functions

Source: https://gridsheet.walkframe.com/getting-started/react

Install the core GridSheet React component and the functions package using npm, yarn, or pnpm. It's recommended to install `@gridsheet/functions` for built-in spreadsheet functions.

```bash
npm install @gridsheet/react-core @gridsheet/functions
```

```bash
yarn add @gridsheet/react-core @gridsheet/functions
```

```bash
pnpm add @gridsheet/react-core @gridsheet/functions
```

--------------------------------

### Svelte App.svelte Example

Source: https://gridsheet.walkframe.com/getting-started/svelte

A basic example of how to import and use Gridsheet components within a Svelte component.

```svelte
<script lang="ts">
  import { Grid } from '@gridsheet/svelte-core';
  import '@gridsheet/svelte-core/style.css';

  const data = [
    { id: 1, name: 'Alice', age: 30 },
    { id: 2, name: 'Bob', age: 25 },
    { id: 3, name: 'Charlie', age: 35 },
  ];

  const columns = [
    { key: 'name', name: 'Name' },
    { key: 'age', name: 'Age' },
  ];
</script>

<Grid data={data} columns={columns} />

```

--------------------------------

### Install Gridsheet Svelte Core and Functions

Source: https://gridsheet.walkframe.com/getting-started/svelte

Install the necessary Gridsheet packages for Svelte integration using npm or yarn.

```bash
npm install @gridsheet/svelte-core @gridsheet/functions
```

--------------------------------

### Package JSON Example for Core Packages

Source: https://gridsheet.walkframe.com/development/package-structure

Shows the versioning format for core GridSheet packages like @gridsheet/react-core and @gridsheet/preact-core.

```json
{
  "name": "@gridsheet/react-core",
  "version": "2.0.0-rc.2"
}

```

```json
{
  "name": "@gridsheet/preact-core", 
  "version": "2.0.0-rc.2"
}

```

--------------------------------

### Install GridSheet Svelte Core and Functions

Source: https://gridsheet.walkframe.com/getting-started/svelte

Install the necessary packages for GridSheet's Svelte component and built-in functions using npm, yarn, or pnpm.

```bash
npm install @gridsheet/svelte-core @gridsheet/functions
```

```bash
yarn add @gridsheet/svelte-core @gridsheet/functions
```

```bash
pnpm add @gridsheet/svelte-core @gridsheet/functions
```

--------------------------------

### Install GridSheet Preact Core and Functions

Source: https://gridsheet.walkframe.com/getting-started/vanilla

Install the necessary packages for GridSheet's Preact integration and built-in spreadsheet functions using npm, yarn, or pnpm.

```bash
npm install @gridsheet/preact-core @gridsheet/functions
# or
yarn add @gridsheet/preact-core @gridsheet/functions
# or
pnpm add @gridsheet/preact-core @gridsheet/functions
```

--------------------------------

### Git Tagging Strategy Example

Source: https://gridsheet.walkframe.com/development/package-structure

Demonstrates the standard git tag format used for releasing GridSheet packages.

```git
@gridsheet/react-core/2.0.0-rc.2
```

```git
@gridsheet/vue-core/2.0.0-rc.2-0
```

--------------------------------

### Package JSON Example for Wrapper Packages

Source: https://gridsheet.walkframe.com/development/package-structure

Illustrates the versioning format for wrapper packages like @gridsheet/vue-core, which includes a wrapper-specific increment.

```json
{
  "name": "@gridsheet/vue-core",
  "version": "2.0.0-rc.2-0"
}

```

--------------------------------

### Run Documentation Server

Source: https://gridsheet.walkframe.com/development/development-guide

Start the documentation development server using the `pnpm doc` command. This is essential for viewing and testing documentation changes locally.

```bash
# Start documentation development server
pnpm doc
```

--------------------------------

### Policy Registration Example

Source: https://gridsheet.walkframe.com/api-reference/props

Register custom policies like 'currency' and 'status' using the useBook hook for use in cell configurations.

```javascript
import { useBook } from '@gridsheet/react-core';

const book = useBook({
  policies: {
    currency: new Policy({ mixins: [CurrencyPolicyMixin] }),
    status: new Policy({ mixins: [StatusPolicyMixin] }),
  },
});

// In initialCells configuration
{
  'A1': {
    value: 1000,
    policy: 'currency',
    style: { backgroundColor: '#f0f9ff' },
  },
  'B1': {
    value: 'Active',
    policy: 'status',
  },
}
```

--------------------------------

### Initial Cell Configuration Example

Source: https://gridsheet.walkframe.com/api-reference/props

Demonstrates how to configure default cell styles, column/row dimensions, individual cell values, policies, and header labels using the initialCells prop.

```javascript
import { ch, rh } from '@gridsheet/react-core';

const initialCells = {
  // Default configuration for all cells
  default: { 
    style: { fontSize: '14px' }
  },
  defaultCol: { width: 100 },
  defaultRow: { height: 30 },
  
  // Header configuration
  '0': { 
    height: 60,  // Header row height
    width: 80,   // Header column width
  },
  
  // Individual cell configuration
  'A1': { value: 'Hello World', style: { color: '#FF0000' } },
  'B2': { value: 100, policy: 'currency' },
  'C3': { value: 'Active', policy: 'status' },
  
  // Column header configuration (width, label only affect headers)
  [ch('A')]: { width: 150, label: 'Name' }, // A0
  [ch(2)]: { width: 200, label: 'Value' }, // B0
  
  // Style for all data cells in column A
  'A': { style: { backgroundColor: '#f9f9f9' } },
 
  // Row header configuration
  [rh(1)]: { height: 40 }, // 01
  [rh(2)]: { height: 50 }, // 02
};

<GridSheet initialCells={initialCells} />
```

--------------------------------

### Dynamic Cell Generation Example

Source: https://gridsheet.walkframe.com/api-reference/utility-functions

Shows how to dynamically generate cells for a multiplication table using `buildInitialCells` and address conversion utilities. This is useful for populating grids with calculated data.

```typescript
import { buildInitialCells, p2a } from '@gridsheet/react-core';

// Generate a multiplication table
const generateMultiplicationTable = (size: number) => {
  const cells: any = {};
  
  // Headers
  for (let i = 0; i <= size; i++) {
    cells[p2a({ y: 1, x: i + 1 })] = { value: i || '', style: { fontWeight: 'bold' } };
    cells[p2a({ y: i + 1, x: 1 })] = { value: i || '', style: { fontWeight: 'bold' } };
  }
  
  // Multiplication values
  for (let row = 1; row <= size; row++) {
    for (let col = 1; col <= size; col++) {
      cells[p2a({ y: row + 1, x: col + 1 })] = { value: row * col };
    }
  }
  
  return buildInitialCells({
    cells,
    ensured: { numRows: size + 1, numCols: size + 1 },
  });
};

const multiplicationTable = generateMultiplicationTable(10);
```

--------------------------------

### Install GridSheet Vue Core and Functions

Source: https://gridsheet.walkframe.com/getting-started/vue

Install the necessary GridSheet packages for Vue.js using npm, yarn, or pnpm. It's recommended to include `@gridsheet/functions` for built-in spreadsheet functions.

```bash
npm install @gridsheet/vue-core @gridsheet/functions
# or
yarn add @gridsheet/vue-core @gridsheet/functions
# or
pnpm add @gridsheet/vue-core @gridsheet/functions
```

--------------------------------

### Example Cell and Registry Implementation

Source: https://gridsheet.walkframe.com/development/architecture

Demonstrates how cells store serializable identifiers and how the registry holds actual object instances. This design supports data integrity and flexibility.

```javascript
// Cell stores only serializable data
const cell = {
  value: "user123",
  policy: "userPolicy",        // Identifier, not the actual policy instance
  custom: { userId: 123 }      // Serializable custom data
}

// Registry (book.registry) stores the actual instances
const book = useBook({
  policies: {
    userPolicy: new UserPolicy(),    // Actual policy instance (handles parsing + rendering)
  },
  additionalFunctions: {
    MY_FUNC: MyFunction,             // Formula function class
  },
  onChange: ({ sheet }) => { /* event handler */ },
});
```

--------------------------------

### E2E Test Example with Playwright

Source: https://gridsheet.walkframe.com/development/development-guide

An example of an end-to-end test using Playwright to verify time and delta calculations in GridSheet.

```typescript
import { test, expect } from '@playwright/test';
import { ctrl, drag, paste } from './utils';

test('time + delta, time + number(days)', async ({ page }) => {
  await page.goto('http://localhost:5233/iframe.html?id=basic-simple--sheet&viewMode=story');
  const a4 = page.locator("[data-address='A4']");
  const b4 = page.locator("[data-address='B4']");
  const c4 = page.locator("[data-address='C4']");
  const a5 = page.locator("[data-address='A5']");

  expect(await a4.locator('.gs-cell-rendered').textContent()).toBe('2022-03-05 12:34:56');
  expect(await b4.locator('.gs-cell-rendered').textContent()).toBe('11:11:11');
  expect(await c4.locator('.gs-cell-rendered').textContent()).toBe('2022-03-05 23:46:07');
  expect(await a5.locator('.gs-cell-rendered').textContent()).toBe('2022-03-04 23:34:56');
});
```

--------------------------------

### Publish Package with pnpm

Source: https://gridsheet.walkframe.com/development/development-guide

Manually publish packages using `pnpm publish`. This command correctly handles `workspace:*` references, preventing installation issues.

```bash
pnpm publish
```

--------------------------------

### Async Cache Key Generation Example

Source: https://gridsheet.walkframe.com/development/architecture

Illustrates how a cache key is generated for an asynchronous formula, combining the function name, argument length, and a hash of the serialized arguments.

```javascript
// Example: GH_REPO("facebook/react", "stars")
// Cache key: "GH_REPO:45:2gosa7pa2gv"
//            funcName:length:base36-hash(up to 11 chars)
```

--------------------------------

### Gridsheet Component Structure (1.x)

Source: https://gridsheet.walkframe.com/history/migration-guide/1to2

Example of how Gridsheet components were structured and initialized in version 1.x, using constructInitialCells and SheetProvider.

```jsx
import * as React from "react";
import {
  GridSheet,
  constructInitialCells,
  BaseFunction,
  prevention,
  SheetProvider,
} from "@gridsheet/react-core";

const ScoreColorRendererMixin: RendererMixinType = {
  number(value: number) {
    if (value < 60) {
      return { style: { backgroundColor: "#ffcccc" } };
    } else if (value < 80) {
      return { style: { backgroundColor: "#ffffcc" } };
    } else {
      return { style: { backgroundColor: "#ccffcc" } };
    }
  }
}

function App() {
  return (
    <SheetProvider>
      <GridSheet
        sheetName={'criteria'}
        initialCells={constructInitialCells({
          matrices: {
            A1: [
              [0, "=A1+60", "=B1+10", "=C1+10", "=D1+10", "=E1+5"],
              ["E🤯", "D🥺", "C😒", "B😚", "A🥰", "S😇"],
            ],
          },
          cells: {
            1: {
              style: { backgroundColor: '#ddd' } 	
            },
          },
        })}
        options={{
          headerHeight: 100,
          headerWidth: 100,
        }}
      />
      <GridSheet
        sheetName={'grades'}
        initialCells={constructInitialCells({
          matrices: {
            A1: [
              ["Name", "Score", "Rank", "Comment"],
              [
                "apple",
                50,
                "=HLOOKUP(B2, criteria!$A$1:$F$2, 2, true)",
                "Pie",
              ],
              ["orange", 82, "=HLOOKUP(B3, criteria!$A$1:$F$2, 2, true)"],
              ["grape", 75, "=HLOOKUP(B4, criteria!$A$1:$F$2, 2, true)"],
              ["melon", 98, "=HLOOKUP(B5, criteria!$A$1:$F$2, 2, true)"],
              ["banana", 65, "=HLOOKUP(B6, criteria!$A$1:$F$2, 2, true)"],
            ],
          },
          cells: {
            B: {
              renderer: ScoreColorRendererMixin,
            }
          }
        })}
      />
    </SheetProvider>
  );
}

```

--------------------------------

### Loading Overlay Until Initialization Completes

Source: https://gridsheet.walkframe.com/examples/case8

Use a MutationObserver to watch for the 'gs-initialized' class and display a loading spinner until the grid is fully interactive. This ensures a smooth user experience during grid setup.

```javascript
const containerRef = React.useRef<HTMLDivElement>(null);
const [ready, setReady] = React.useState(false);
 
React.useEffect(() => {
  const el = containerRef.current;
  if (!el) return;
  const observer = new MutationObserver(() => {
    if (el.querySelector('.gs-initialized')) {
      setReady(true);
      observer.disconnect();
    }
  });
  observer.observe(el, { attributes: true, subtree: true, attributeFilter: ['class'] });
  if (el.querySelector('.gs-initialized')) {
    setReady(true);
  }
  return () => observer.disconnect();
}, []);
 
return (
  <div ref={containerRef} style={{ position: 'relative' }}>
    <GridSheet ... />
    {!ready && (
      <div style={{ position: 'absolute', inset: 0, background: 'rgba(255,255,255,0.8)', display: 'flex', alignItems: 'center', justifyContent: 'center' }}>
        <div className="gs-loading-spinner" />
      </div>
    )}
  </div>
);
```

--------------------------------

### Registering a Currency Policy with useBook

Source: https://gridsheet.walkframe.com/api-reference/policy

Register a custom policy named 'currency' using `useBook` and apply it to cells. This example uses `ThousandSeparatorPolicyMixin` for formatting.

```typescript
import { GridSheet, Policy, useBook, ThousandSeparatorPolicyMixin } from '@gridsheet/react-core';
 
function MySheet() {
  const book = useBook({
    policies: {
      currency: new Policy({ mixins: [ThousandSeparatorPolicyMixin] }),
    },
  });
 
  return (
    <GridSheet
      book={book}
      initialCells={{
        B: { policy: 'currency' },
        'B1': { value: 1234567.89 },
      }}
    />
  );
}
```

--------------------------------

### Gridsheet Component Structure (2.x)

Source: https://gridsheet.walkframe.com/history/migration-guide/1to2

Example of Gridsheet component initialization in version 2.x, utilizing buildInitialCells, useHub, and Renderer for custom renderers.

```jsx
import * as React from "react";
import {
  GridSheet,
  buildInitialCells,
  useHub,
  Renderer,
  RendererMixinType,
  RenderProps,
  makeBorder,
} from "@gridsheet/react-core";

// Updated renderer with new method signature
const ScoreColorRendererMixin: RendererMixinType = {
  number({ value }: RenderProps<number>) {
    if (value < 60) {
      return { style: { backgroundColor: "#ffcccc" } };
    } else if (value < 80) {
      return { style: { backgroundColor: "#ffffcc" } };
    } else {
      return { style: { backgroundColor: "#ccffcc" } };
    }
  }
}

function App() {
  const hub = useHub({
    renderers: {
      scoreColor: new Renderer({ mixins: [ScoreColorRendererMixin] }),
    },
  });

  return (
    <>
      <GridSheet
        hub={hub}
        sheetName={'criteria'}
        initialCells={buildInitialCells({
          matrices: {
            A1: [
              [0, "=A1+60", "=B1+10", "=C1+10", "=D1+10", "=E1+5"],
              ["E🤯", "D🥺", "C😒", "B😚", "A🥰", "S😇"],
            ],
          },
          cells: {
            1: {
              style: {
                backgroundColor: '#ddd',
                ...makeBorder({ all: '1px solid #ccc' })
              } 	
            },
          },
        })}
      />
      <GridSheet
        hub={hub}
        sheetName={'grades'}
        initialCells={buildInitialCells({
          matrices: {
            A1: [
              ["Name", "Score", "Rank", "Comment"],
              [
                "apple",
                50,
                "=HLOOKUP(B2, criteria!$A$1:$F$2, 2, true)",
                "Pie",
              ],
              ["orange", 82, "=HLOOKUP(B3, criteria!$A$1:$F$2, 2, true)"],
              ["grape", 75, "=HLOOKUP(B4, criteria!$A$1:$F$2, 2, true)"],
              ["melon", 98, "=HLOOKUP(B5, criteria!$A$1:$F$2, 2, true)"],
              ["banana", 65, "=HLOOKUP(B6, criteria!$A$1:$F$2, 2, true)"],
            ],
          },
          cells: {
            B: {
              renderer: 'scoreColor',
            }
          }
        })}
      />
    </>
  );
}

```

--------------------------------

### Create a Custom Policy with Dropdown and Validation

Source: https://gridsheet.walkframe.com/api-reference/policy

Example of creating a custom policy mixin that provides dropdown options and validates user input for a color selection.

```typescript
import { Policy, PolicyMixinType, AutocompleteOption, SelectProps } from '@gridsheet/react-core';

const ColorPolicyMixin: PolicyMixinType = {
  getSelectOptions(): AutocompleteOption[] {
    return [
      { value: 'red',   label: <span style={{ color: 'red' }}>Red</span> },
      { value: 'green', label: <span style={{ color: 'green' }}>Green</span> },
      { value: 'blue',  label: <span style={{ color: 'blue' }}>Blue</span> },
    ];
  },
  select({ next, current }: SelectProps) {
    const allowed = ['red', 'green', 'blue'];
    if (allowed.includes(next?.value)) {
      return { value: next!.value, style: { backgroundColor: next!.value } };
    }
    // Preserve current value if input is invalid
    return current ?? { value: null };
  },
};

const colorPolicy = new Policy({ mixins: [ColorPolicyMixin], priority: 2 });
```

--------------------------------

### Load Dynamic Data into GridSheet

Source: https://gridsheet.walkframe.com/examples/case2

Populate the grid starting from cell A1 using `buildInitialCellsFromOrigin` with fetched data. GridSheet initializes with this data only once, so use a loading flag for dynamic updates.

```javascript
<GridSheet
  book={book}
  sheetName="contributors"
  initialCells={buildInitialCellsFromOrigin({
    matrix: data,   // the state value from useState
    cells: { ... }, // column styles and header definitions go here
  })}
/>
```

--------------------------------

### Registering a Policy with useSpellbook

Source: https://gridsheet.walkframe.com/api-reference/policy

Register a custom policy using `useSpellbook`, which pre-loads extended formula functions. This example demonstrates registering a 'currency' policy with `ThousandSeparatorPolicyMixin`.

```typescript
import { GridSheet, Policy, ThousandSeparatorPolicyMixin } from '@gridsheet/react-core';
import { useSpellbook } from '@gridsheet/react-core/spellbook';
 
function MySheet() {
  const book = useSpellbook({
    policies: {
      currency: new Policy({ mixins: [ThousandSeparatorPolicyMixin] }),
    },
  });
 
  return (
    <GridSheet
      book={book}
      initialCells={{
        B: { policy: 'currency' },
        'B1': { value: 1234567.89 },
      }}
    />
  );
}
```

--------------------------------

### Creating a Policy by Subclassing

Source: https://gridsheet.walkframe.com/api-reference/policy

Define a custom policy by extending the base `Policy` class and overriding methods like `renderString` to modify behavior. This example creates a policy that converts cell values to uppercase.

```typescript
import { Policy, RenderProps } from '@gridsheet/react-core';
 
class UpperCasePolicy extends Policy {
  override renderString({ value }: RenderProps<string>) {
    return value?.toUpperCase() ?? '';
  }
}
 
const upperCasePolicy = new UpperCasePolicy();
```

--------------------------------

### Coordinate and Address Conversion Example

Source: https://gridsheet.walkframe.com/api-reference/utility-functions

Demonstrates converting between programmatic coordinates (x, y) and cell addresses (e.g., 'F10') using various utility functions. Includes column and row number conversions.

```tsx
import { x2c, c2x, y2r, r2y, p2a, a2p } from '@gridsheet/react-core';

// Working with programmatic coordinates
const colIndex = 5;
const rowIndex = 10;

// Convert to address
const address = p2a({ y: rowIndex, x: colIndex });
console.log(address); // 'F10'

// Convert back to coordinates
const point = a2p(address);
console.log(point); // `{ y: 10, x: 5 }`

// Column operations
const colLetter = x2c(colIndex);
console.log(colLetter); // 'F'

const backToIndex = c2x(colLetter);
console.log(backToIndex); // 5

// Row operations
const rowNumber = y2r(rowIndex);
console.log(rowNumber); // 10

const backToRowIndex = r2y(rowNumber);
console.log(backToRowIndex); // 10
```

--------------------------------

### Formula-based Calculations and Summary Rows

Source: https://gridsheet.walkframe.com/examples/case10

Illustrates how to define matrices with formulas for calculations and summary rows using functions like SUM, COUNTA, and COUNTIF. This setup allows for dynamic data aggregation and analysis within the sheet.

```javascript
matrices: {
  A1: [
    [null, 'Laptop Pro X1', 'Electronics', 15, 1299.99, '=D1*E1'],
    // ...
  ],
  B22: [['TOTAL', '', '=SUM(D1:D21)', '', '=SUM(F1:F21)']],
  B23: [['Items', '', '=COUNTA(B1:B21)']],
  B24: [['Low Stock', '', '=COUNTIF(D1:D21,"<=10")']],
},
```

--------------------------------

### Build Documentation

Source: https://gridsheet.walkframe.com/development/development-guide

Build the project documentation for deployment using the `pnpm build:docs` command.

```bash
# Build documentation
pnpm build:docs
```

--------------------------------

### Main Entry Point for Preact App

Source: https://gridsheet.walkframe.com/getting-started/vanilla

Renders the main App component into the DOM, setting up the Preact application's entry point.

```javascript
import { render } from 'preact'
import './index.css'
import { App } from './app.jsx'

render(<App />, document.getElementById('app'))
```

--------------------------------

### Internal Formula Storage Example

Source: https://gridsheet.walkframe.com/development/architecture

Formulas in GridSheet use internal IDs for cell references, ensuring stability when rows or columns are modified. This example shows the internal storage format.

```javascript
// Internal formula storage
"=SUM(#2!#0:#4)"  // Uses internal IDs (sheet ID + cell IDs)
```

--------------------------------

### Usage Example: GetProps refEvaluation (1.x vs 2.x)

Source: https://gridsheet.walkframe.com/history/migration-guide/1to2

Shows how to use the 'evaluates' property in Gridsheet 1.x and its equivalent 'refEvaluation' property in Gridsheet 2.x when calling table.getCell. The examples illustrate the mapping between the old boolean values and the new string enum values for reference evaluation.

```typescript
// Before (1.x)
table.getCell({ y: 1, x: 1 }, { evaluates: true });
table.getCell({ y: 1, x: 1 }, { evaluates: false });
table.getCell({ y: 1, x: 1 }, { evaluates: null });
```

```typescript
// After (2.x)
table.getCell({ y: 1, x: 1 }, { refEvaluation: 'COMPLETE' });
table.getCell({ y: 1, x: 1 }, { refEvaluation: 'RAW' });
table.getCell({ y: 1, x: 1 }, { refEvaluation: 'SYSTEM' });
```

--------------------------------

### removeCols

Source: https://gridsheet.walkframe.com/api-reference/sheet

Removes a specified number of columns starting from a given position `x`.

```APIDOC
## removeCols

### Description
Removes columns starting at position `x`.

### Method
`removeCols(args: { x: number; numCols: number; reflection?: StorePatchType }): UserSheet`

### Parameters
#### Path Parameters
- **x** (number) - Required - The starting column index for removal.
- **numCols** (number) - Required - The number of columns to remove.
- **reflection** (StorePatchType) - Optional - A patch to apply for reflection.

### Request Example
```javascript
if (!sheetRef.current) return;
const { sheet, apply } = sheetRef.current;

const newSheet = sheet.removeCols({ x: 2, numCols: 3 });
apply(newSheet); // Required to apply changes
```
```

--------------------------------

### Remove Columns

Source: https://gridsheet.walkframe.com/api-reference/sheet

Removes a specified number of columns starting from a given position.

```typescript
if (!sheetRef.current) return;
const { sheet, apply } = sheetRef.current;
 
const newSheet = sheet.removeCols({ x: 2, numCols: 3 });
apply(newSheet); // Required to apply changes
```

--------------------------------

### buildInitialCellsFromOrigin

Source: https://gridsheet.walkframe.com/api-reference/utility-functions

Creates initial cells configuration from matrix data, automatically generating column names.

```APIDOC
## buildInitialCellsFromOrigin(config: InitialCellsOriginConfig)

### Description
Creates initial cells configuration from matrix data, automatically generating column names.

### Parameters
#### Path Parameters
- None

#### Query Parameters
- None

#### Request Body
- **config** (InitialCellsOriginConfig) - Required - Configuration with matrix data and options
  - **matrix** (MatrixType) - Required - 2D array of data
  - **origin** (Address) - Required - Starting address for the matrix
  - **cells** (CellsByAddressType) - Optional - Individual cell data and configuration
  - **ensured** ({ numRows?: number; numCols?: number }) - Optional - Minimum table dimensions
  - **flattenAs** (keyof CellType) - Optional - Property to flatten matrix into

### Request Example
```javascript
import { buildInitialCellsFromOrigin } from '@gridsheet/react-core';

const data = [
  ['Name', 'Age', 'City'],
  ['John', 25, 'New York'],
  ['Jane', 30, 'Los Angeles'],
  ['Bob', 35, 'Chicago'],
];

const initialCells = buildInitialCellsFromOrigin({
  matrix: data,
  origin: 'A1',
  ensured: {
    numRows: 20,
    numCols: 10,
  },
});
```

### Response
#### Success Response (200)
- **initialCells** (object) - The formatted initial cells configuration.

#### Response Example
```json
{
  "example": "// GridSheet component usage\n<GridSheet initialCells={initialCells} />"
}
```
```

--------------------------------

### Get Cell Policy

Source: https://gridsheet.walkframe.com/api-reference/sheet

Retrieve the Policy instance applied to a specific cell using its coordinates.

```typescript
const policy = sheet.getPolicy({ y: 1, x: 1 });
```

--------------------------------

### Migrate Header Configuration: Global Options to Table Settings (v1.x to v2.x)

Source: https://gridsheet.walkframe.com/history/migration-guide/1to2

Before: Setting header height and width via global options. After: Configuring header dimensions using initialCells or table methods.

```javascript
<GridSheet
  options={{
    headerHeight: 100,
    headerWidth: 100,
  }}
/>
```

```javascript
<GridSheet
  initialCells={buildInitialCells({
    cells: {
      0: {
        width: 100, // Set header width
        height: 100, // Set header height
      },
    }
  })}
/>
```

```javascript
table.setHeaderHeight(100);
table.setHeaderWidth(100);
```

--------------------------------

### historyIndex

Source: https://gridsheet.walkframe.com/api-reference/sheet

Gets the current position within the history stack, indicating how many operations have been undone or redone.

```APIDOC
## historyIndex()

### Description
Returns the current position in the history stack.

### Method
N/A (This is a method call, not an HTTP endpoint)

### Endpoint
N/A

### Parameters
None

### Response
#### Success Response
- **return value** (number) - The index representing the current position in the history stack.

### Request Example
```javascript
const currentIndex = sheet.historyIndex();
```
```

--------------------------------

### Build Storybook

Source: https://gridsheet.walkframe.com/development/development-guide

Generate a static build of the Storybook for deployment using `pnpm build:storybook`.

```bash
# Build Storybook
pnpm build:storybook
```

--------------------------------

### Get Last Changed Cell Addresses

Source: https://gridsheet.walkframe.com/api-reference/sheet

Retrieve an array of cell addresses that were modified during the most recent operation.

```typescript
const changed = sheet.getLastChangedAddresses();
console.log(changed); // e.g. ['A1', 'B2']
```

--------------------------------

### v3 Sheet and Store Handle Initialization and Usage

Source: https://gridsheet.walkframe.com/history/migration-guide/2to3

This snippet demonstrates the v3 approach using `useSheetRef` and `useStoreRef` hooks for accessing sheet data and UI state, respectively. It also shows how to apply updates to the store and pass the refs to the GridSheet component.

```javascript
import {
  GridSheet,
  useSheetRef,
  useStoreRef,
} from '@gridsheet/react-core';

const sheetRef = useSheetRef();
const storeRef = useStoreRef();

// read sheet data
const sheet = sheetRef.current?.sheet;

// programmatically move the cursor
const store = storeRef.current?.store;
storeRef.current?.apply({ ...store, choosing: { y: 2, x: 3 } });

return (
  <GridSheet
    sheetRef={sheetRef}
    storeRef={storeRef}
    initialCells={initialCells}
  />
);
```

--------------------------------

### BaseFunction Type Definition

Source: https://gridsheet.walkframe.com/api-reference/formula

Defines the structure for custom Gridsheet formulas, including properties for examples, descriptions, argument definitions, and caching.

```typescript
class BaseFunction {
  // Formula example shown in autocomplete
  example?: string;

  // Short description of the function
  description?: string;

  // Function category for grouping in autocomplete
  category: FunctionCategory = 'other';

  // Argument definitions (drives arg-count and type validation)
  defs: FunctionArgumentDefinition[] = [];

  // Cache TTL in milliseconds (async only). undefined = never expires.
  protected ttlMilliseconds?: number;

  // Hash segments in cache key. Higher = lower collision risk. Default: 1
  protected hashPrecision: number;

  // If true, reuse the same in-flight Promise for matching cache keys. Default: true
  protected useInflight: boolean;

  // If true, broadcasting is unconditionally disabled for this function. Default: false
  protected broadcastDisabled: boolean;

  // If true, wraps return value in a Spilling sentinel for spill behaviour. Default: false
  protected autoSpilling: boolean;

  // Main function implementation
  protected main(...args: any[]): any;

  // Optional: override to customise argument coercion before main() is called
  protected validate(args: any[]): any[];
}

type FunctionCategory =
  | 'math' | 'statistics' | 'text' | 'time' | 'lookup'
  | 'information' | 'finance' | 'engineering' | 'logical' | 'other';

type FunctionArgumentDefinition = {
  name: string;
  description: string;
  optional?: boolean;      // allows fewer args than defs.length
  variadic?: boolean;      // last matching def receives all remaining args
  nullable?: boolean;      // blank treated as 0 / "" etc. (default: true)
  errorTolerant?: boolean; // forward FormulaError values instead of throwing
  acceptedTypes?: FunctionArgumentType[]; // runtime type check
  takesMatrix?: boolean;   // suppresses broadcasting for this arg
};

type FunctionArgumentType =
  | 'number' | 'string' | 'boolean'
  | 'date' | 'time' | 'matrix' | 'reference' | 'any';
```

--------------------------------

### Create a Custom Formula

Source: https://gridsheet.walkframe.com/api-reference/formula

Extend BaseFunction to create custom formula functions. Define example usage, descriptions, and argument documentation.

```typescript
import { BaseFunction, FunctionArgumentDefinition } from '@gridsheet/react-core';
 
class MyCustomFunction extends BaseFunction {
  // Display name and example usage
  example = 'MY_FUNC(arg1, arg2)';
  
  // Optional: description of what this function does
  description = 'Description of what this function does';
  
  // Argument documentation (also drives arg-count validation)
  defs: FunctionArgumentDefinition[] = [
    { name: 'arg1', description: 'Description of first argument', acceptedTypes: ['string'] },
    { name: 'arg2', description: 'Description of second argument', acceptedTypes: ['number'] }
  ];
 
  // The main function logic
  protected main(stringArg: string, numberArg: number) {
    // Your logic here
    return result;
  }
}
```

--------------------------------

### Migrate Utility Function Names: constructInitialCells to buildInitialCells (v1.x to v2.x)

Source: https://gridsheet.walkframe.com/history/migration-guide/1to2

Before: Using constructInitialCells and constructInitialCellsOrigin. After: Using the renamed buildInitialCells and buildInitialCellsFromOrigin.

```javascript
import { constructInitialCells, constructInitialCellsOrigin } from "@gridsheet/react-core";
```

```javascript
import { buildInitialCells, buildInitialCellsFromOrigin } from "@gridsheet/react-core";
```

--------------------------------

### Registering Custom Formulas with useSpellbook

Source: https://gridsheet.walkframe.com/api-reference/formula

Registers custom formulas using `useSpellbook`, which includes all built-in extended functions. Requires `@gridsheet/functions` to be installed.

```typescript
import { useSpellbook } from '@gridsheet/react-core/spellbook';

const book = useSpellbook({
  additionalFunctions: {
    my_func: MyCustomFunction,
    fetch_weather: FetchWeather,
  },
});
```

--------------------------------

### Creating Refs

Source: https://gridsheet.walkframe.com/api-reference/props

Demonstrates how to create `sheetRef` and `storeRef` using hooks within components or factory functions outside of components.

```APIDOC
## Creating refs
Use the provided hooks (inside a component) or factory functions (outside):
```javascript
import { useSheetRef, useStoreRef, createSheetRef, createStoreRef } from '@gridsheet/react-core';

// Inside a component
const sheetRef = useSheetRef();
const storeRef = useStoreRef();

// Outside a component (e.g. in a class or module)
const sheetRef = createSheetRef();
const storeRef = createStoreRef();
```
```

--------------------------------

### Migrate TableRef and StoreRef to Connector (v1.x to v2.x)

Source: https://gridsheet.walkframe.com/history/migration-guide/1to2

Before: Using separate useTableRef and useStoreRef hooks. After: Using the unified useConnector hook for both table and store managers.

```javascript
import { useTableRef, useStoreRef } from '@gridsheet/react-core';

const tableRef = useTableRef();
const storeRef = useStoreRef();

<GridSheet tableRef={tableRef} storeRef={storeRef} initialCells={initialCells} />

// Access table
const { table, apply } = tableRef.current;
// Access store
const { store, apply } = storeRef.current;
```

```javascript
import { useConnector } from '@gridsheet/react-core';

const connector = useConnector();

<GridSheet connector={connector} initialCells={initialCells} />

// Access table manager
const { tableManager } = connector.current;
const { table, apply } = tableManager;

// Access store manager
const { storeManager } = connector.current;
const { store, apply } = storeManager;
```

--------------------------------

### Policy Mixin with `EVALUATED` Resolution

Source: https://gridsheet.walkframe.com/api-reference/sheet

Example of using `'EVALUATED'` resolution within a `renderSheet` policy mixin to receive range formulas as `Sheet` objects.

```javascript
const ChartPolicyMixin: PolicyMixinType = {
  renderSheet({ value }: RenderProps<UserSheet>) {
    // value is the Sheet spanning the referenced range (e.g. C1:F1)
    const matrix = toValueMatrix(value);
    // ... render chart from matrix data
  },
};
```

--------------------------------

### Using `getCell` with Resolution Options

Source: https://gridsheet.walkframe.com/api-reference/sheet

Demonstrates how to use the `getCell` method with different `resolution` options to control formula evaluation.

```javascript
// Default: =C1:F1 → scalar value of C1
sheet.getCell({ y: 1, x: 2 });

// EVALUATED: =C1:F1 → Sheet object spanning C1:F1
sheet.getCell({ y: 1, x: 2 }, { resolution: 'EVALUATED' });

// RAW: =C1:F1 → '=C1:F1' string
sheet.getCell({ y: 1, x: 2 }, { resolution: 'RAW' });
```

--------------------------------

### Development Scripts

Source: https://gridsheet.walkframe.com/development/development-guide

Common scripts for running development servers, tests, and linters.

```bash
pnpm dev

pnpm doc

pnpm test

pnpm e2e

pnpm lint:fix
```

--------------------------------

### Reading Sheet Data as a Value Object

Source: https://gridsheet.walkframe.com/api-reference/sheet

Get cell values as an object keyed by address using `toValueObject`. Allows filtering by specific addresses.

```javascript
const values = toValueObject(sheet);
console.log(values['A1']); // value of A1

// Only specific addresses
const partial = toValueObject(sheet, { addresses: ['A1', 'B2', 'C3'] });
```

--------------------------------

### Run Tests

Source: https://gridsheet.walkframe.com/development/development-guide

Execute all project tests to ensure code quality and stability before submitting changes. Use `pnpm test` for this purpose.

```bash
pnpm test
```

--------------------------------

### Log Cell Changes with onChange

Source: https://gridsheet.walkframe.com/examples/case10

Fires after any cell mutation. Use `getLastChangedAddresses()` to get the exact addresses of modified cells, which is more precise than tracking `points`.

```typescript
onChange: ({ sheet }: { sheet: UserSheet }) => {
  const addresses = sheet.getLastChangedAddresses();
  if (addresses.length > 0) {
    addActivityLog(`✏️ Cells changed: ${addresses.join(', ')}`);
  }
  setTsv(convertToTSV(sheet));
},
```

--------------------------------

### buildInitialCells(config: InitialCellsConfig): any

Source: https://gridsheet.walkframe.com/api-reference/utility-functions

Initializes cells with provided configurations, including direct cell data, matrices, and ensuring a minimum number of rows/columns.

```APIDOC
## buildInitialCells(config: InitialCellsConfig): any

### Description
Initializes cells with provided configurations. This can include direct cell data, matrices, and ensuring a minimum number of rows and columns.

### Parameters
#### Path Parameters
- **config** (InitialCellsConfig) - Required - Configuration object for initializing cells.
  - **matrices** (MatricesByAddress<any>) - Optional - Matrix data.
  - **cells** (CellsByAddressType) - Optional - Direct cell data keyed by address.
  - **ensured** (object) - Optional - Ensures a minimum number of rows and columns.
    - **numRows** (number) - Optional - Minimum number of rows.
    - **numCols** (number) - Optional - Minimum number of columns.
  - **flattenAs** (keyof CellType) - Optional - Specifies how to flatten cell data.

### Response
#### Success Response
- **any** - The result of building initial cells.

### Response Example
```json
{
  // ... structure representing initialized cells ...
}
```

### Usage Example
```javascript
import { buildInitialCells, rh, ch } from '@gridsheet/react-core';

buildInitialCells({
  cells: {
    [rh(6)]: { sortFixed: true, filterFixed: true },
    [ch('A')]: { width: 150, label: 'Product' },
  },
  ensured: { numRows: 10, numCols: 5 },
});
```
```

--------------------------------

### Ensuring Grid Size with `ensured` Option

Source: https://gridsheet.walkframe.com/examples/case3

Use the `ensured` option within `buildInitialCells` to pre-allocate a minimum number of rows and columns. This is vital for creating a blank canvas where all cells should be accessible.

```javascript
buildInitialCells({
  cells: {
    defaultRow: { height: 25 },
    defaultCol: { width: 25 },
    ...getSavedData(),
  },
  ensured: {
    numRows: 50,
    numCols: 50,
  },
})
```

--------------------------------

### Formula Display Conversion Example

Source: https://gridsheet.walkframe.com/development/architecture

Internal cell IDs are converted to human-readable addresses (e.g., 'A1') for display purposes. This ensures a familiar user experience.

```javascript
// Display conversion
"=SUM('Sheet2'!A1:A5)"    // Converted to addresses for display
```

--------------------------------

### Update Hub Configuration with Event Handlers

Source: https://gridsheet.walkframe.com/history/migration-guide/1to2

Configure the hub with renderers and move event handlers from options to the hub configuration.

```javascript
const hub = useHub({
  renderers: {
    myRenderer: new Renderer({ mixins: [MyRenderer] }),
  },
  // Move event handlers from options to hub
  onChange: ({ table, points }) => {
    console.log('Data changed:', points);
  },
  onSave: ({ table, points }) => {
    console.log('Data saved:', points);
  },
  onSelect: ({ table, points }) => {
    console.log('Selection changed:', points);
  },
  onRemoveRows: ({ table, ys }) => {
    console.log('Rows removed:', ys);
  },
  onRemoveCols: ({ table, xs }) => {
    console.log('Columns removed:', xs);
  },
  onInsertRows: ({ table, y, numRows }) => {
    console.log('Rows inserted at position', y, 'count:', numRows);
  },
  onInsertCols: ({ table, x, numCols }) => {
    console.log('Columns inserted at position', x, 'count:', numCols);
  },
  onKeyUp: ({ e, points }) => {
    console.log('Key pressed:', e.key, 'at position:', points);
  },
  onInit: (table) => {
    console.log('Table initialized:', table.sheetName);
  },
});
```

--------------------------------

### Cell Policy Configuration

Source: https://gridsheet.walkframe.com/examples/case11

Defines the policy for a cell, specifying how its value is interpreted or handled. This example sets the policy to 'repo' for cell A1 in the 'GithubRepos' sheet.

```json
1{
2  "policy": "repo",
3  "value": "facebook/react"
4}
```