docs: add AGENTS.md for AI coding assistants

AGENTS.md

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+# AGENTS.md - nutrient-font-tool
+
+Guidelines for AI coding assistants working on this repository.
+
+## Overview
+
+This is a CLI tool that generates `fonts.json` metadata for Nutrient PDF SDK font bundles.
+
+## Architecture
+
+```
+nutrient-font-tool/
+├── bin/cli.js          # CLI entry point
+├── lib/
+│   ├── bundle.js       # Main logic: scan fonts, generate JSON
+│   └── wasm-loader.js  # Loads and interfaces with WASM module
+├── wasm/
+│   ├── FontToolWASM.js   # Emscripten-generated JS loader
+│   └── FontToolWASM.wasm # Compiled WebAssembly binary
+└── test/
+    └── bundle.test.js  # Vitest tests
+```
+
+## Important: WASM Binary
+
+**The `wasm/` directory contains pre-compiled binaries.** The source code is not in this repository.
+
+- Do NOT attempt to modify, regenerate, or reverse-engineer the WASM files
+- Do NOT ask users for the WASM source code
+- The WASM binary is built from private source code and distributed in compiled form
+- Treat `wasm/FontToolWASM.js` and `wasm/FontToolWASM.wasm` as opaque dependencies
+
+### WASM Interface
+
+The WASM module exports:
+- `allocateMemory(size)` → `MemoryHandle` - Allocate memory for font data
+- `processFont(memoryHandle, filename)` → `string` - Process font, returns JSON string
+
+The `MemoryHandle` object has:
+- `.view` - Uint8Array view into WASM memory (copy data here)
+- `.delete()` - Free the memory (always call when done)
+
+## What You CAN Modify
+
+- `bin/cli.js` - CLI argument parsing, user interaction
+- `lib/bundle.js` - File scanning, JSON generation, output handling
+- `lib/wasm-loader.js` - How we call into WASM (but not the WASM itself)
+- `test/` - Tests
+- Documentation, CI workflows, package.json
+
+## What You Should NOT Modify
+
+- `wasm/FontToolWASM.js` - Generated file, do not edit
+- `wasm/FontToolWASM.wasm` - Binary, cannot edit
+
+## Testing
+
+```bash
+npm test              # Run tests once
+npm run test:watch    # Watch mode
+```
+
+Tests use a small fixture font (`test/fixtures/Anton-Regular.ttf`).
+
+## Code Style
+
+- ES modules (`import`/`export`)
+- Node.js 18+ features are OK
+- Keep dependencies minimal
+- Async/await for file operations

LICENSE

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+MIT License
+
+Copyright (c) 2026 Nutrient GmbH
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+---
+
+WASM Binary Components
+
+The files in the `wasm/` directory (FontToolWASM.js, FontToolWASM.wasm) are
+proprietary components compiled from Nutrient source code. These binaries are
+distributed under the Nutrient SDK License Agreement.
+
+See https://nutrient.io/legal/terms for terms and conditions.

wasm/README.md

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+# FontToolWASM
+
+Pre-compiled WebAssembly module for parsing font metadata.
+
+## ⚠️ Do Not Modify
+
+These files are **pre-compiled binaries** built from private source code:
+
+- `FontToolWASM.js` - Emscripten-generated JavaScript loader
+- `FontToolWASM.wasm` - Compiled WebAssembly binary
+
+**Do not edit, regenerate, or reverse-engineer these files.**
+
+## What It Does
+
+The WASM module parses font files (TTF, OTF, TTC, OTC) and extracts metadata:
+
+- Font names (family, full name, subfamily)
+- Unicode code point coverage
+- Embedding permissions
+- Font weight
+- SHA1 hash
+
+## Usage
+
+```javascript
+import FontToolModule from './FontToolWASM.js';
+
+// Initialize the module
+const wasm = await FontToolModule();
+
+// Allocate memory for font data
+const fontBuffer = await fs.readFile('MyFont.ttf');
+const memoryHandle = wasm.allocateMemory(fontBuffer.byteLength);
+
+// Copy font data into WASM memory
+new Uint8Array(memoryHandle.view).set(new Uint8Array(fontBuffer.buffer));
+
+// Process the font
+const jsonString = wasm.processFont(memoryHandle, 'MyFont.ttf');
+const fontInfo = JSON.parse(jsonString);
+
+// Always free memory when done
+memoryHandle.delete();
+```
+
+## API
+
+### `allocateMemory(size: number): MemoryHandle`
+
+Allocates memory in the WASM heap for font data.
+
+### `processFont(handle: MemoryHandle, filename: string): string`
+
+Parses font data and returns JSON string with font metadata.
+
+### `MemoryHandle`
+
+- `.view` - Uint8Array view into allocated memory
+- `.size` - Size of allocation in bytes  
+- `.delete()` - Free the memory (must call when done)
+
+## Output Format
+
+```json
+{
+  "name": {
+    "family": "Noto Sans",
+    "fullName": "Noto Sans Regular",
+    "subfamily": "Regular"
+  },
+  "filePath": "NotoSans-Regular.ttf",
+  "codePoints": [[32, 126], [160, 255]],
+  "sha1": "abc123...",
+  "allowedToEmbed": true,
+  "weight": 5
+}
+```