neptune-privacy/TAURI_WASM_FIX.md

# Tauri + WASM Integration Fix

## 🔍 Problem

WASM works in browser (`npm run dev`) but fails in Tauri webview (`npm run tauri:dev`) with error:
```
Cannot assign to read only property 'toString' of object '#<AxiosURLSearchParams>'
```

## ✅ Solutions Applied

### 1. **CSP (Content Security Policy) Update**

**File:** `src-tauri/tauri.conf.json`

Added required CSP directives for WASM:

```json
{
  "security": {
    "csp": {
      "default-src": "'self' 'unsafe-inline' asset: https://asset.localhost",
      "script-src": "'self' 'unsafe-inline' 'unsafe-eval' 'wasm-unsafe-eval'",
      // ... other directives with asset: protocol
    },
    "assetProtocol": {
      "enable": true,
      "scope": ["**"]
    }
  }
}
```

**Key changes:**
- ✅ Added `'wasm-unsafe-eval'` to `script-src` - **REQUIRED for WASM execution in Tauri 2.x**
- ✅ Added `asset:` and `https://asset.localhost` to relevant directives
- ✅ Enabled `assetProtocol` to serve assets with proper MIME types

### 2. **Vite Config Update**

**File:** `vite.config.ts`

```typescript
export default defineConfig({
  optimizeDeps: {
    exclude: ['@neptune/native'],  // Only exclude native module
    // ❌ NOT excluding @neptune/wasm - it must be bundled!
  },

  build: {
    assetsInlineLimit: 0,  // Don't inline WASM as base64
  },

  assetsInclude: ['**/*.wasm'],  // Serve WASM with correct MIME type
})
```

**Key changes:**
- ✅ Removed `@neptune/wasm` from `exclude` and `external`
- ✅ Added `assetsInlineLimit: 0` to prevent base64 encoding
- ✅ Added `assetsInclude` for WASM MIME type

### 3. **Package.json Fix**

```json
{
  "dependencies": {
    "axios": "^1.7.9"  // Fixed from invalid "1.13.2"
  }
}
```

## 🧪 Testing

### 1. Browser (Should work)
```bash
npm run dev
```
Open http://localhost:5173/auth → Create wallet → Should work

### 2. Tauri (Should work now)
```bash
npm run tauri:dev
```
Create wallet → Should work without CSP/WASM errors

## 🐛 Additional Debugging

### If WASM still doesn't load:

#### Check 1: WASM File in Dist
```bash
npm run build
ls dist/assets/*.wasm  # Should see neptune_wasm_bg-*.wasm
```

#### Check 2: Browser DevTools (in Tauri)
1. Open Tauri app
2. Right-click → Inspect Element
3. Console tab → Check for errors
4. Network tab → Filter `.wasm` → Check if WASM loads (200 status)

#### Check 3: CSP Errors
In DevTools Console, look for:
```
Refused to execute WebAssembly script...
```
If you see this → CSP is still blocking WASM

### Temporary Debug: Disable CSP

If nothing works, temporarily disable CSP to isolate the issue:

```json
// src-tauri/tauri.conf.json
{
  "security": {
    "dangerousDisableAssetCspModification": true,  // Disable CSP temporarily
    "csp": null  // Remove CSP entirely for testing
  }
}
```

⚠️ **WARNING:** Only use this for debugging! Re-enable CSP for production.

## 📝 Why This Happens

### Tauri vs Browser Differences

| Feature | Browser | Tauri Webview |
|---------|---------|---------------|
| CSP | Permissive by default | Strict by default |
| WASM | Always allowed | Needs `'wasm-unsafe-eval'` |
| Asset loading | HTTP(S) | Custom `asset://` protocol |
| MIME types | Auto-detected | Must be configured |

### WASM Loading in Tauri

1. Vite bundles WASM file → `dist/assets/neptune_wasm_bg-*.wasm`
2. Tauri serves it via `asset://localhost/assets/...`
3. CSP must allow:
   - `script-src 'wasm-unsafe-eval'` → Execute WASM
   - `connect-src asset:` → Fetch WASM file
4. AssetProtocol must serve with `Content-Type: application/wasm`

## 🔄 Next Steps After Fix

### 1. Test Full Wallet Flow
- ✅ Generate wallet (WASM)
- ✅ Display seed phrase
- ✅ Confirm seed phrase
- 🚧 Create keystore (needs Tauri commands)

### 2. Implement Tauri Commands
See `TAURI_COMMANDS_TODO.md` (if it exists, otherwise create it)

### 3. Build & Test Production
```bash
npm run tauri:build
```

## 📚 References

- [Tauri CSP Documentation](https://tauri.app/v2/reference/config/#securityconfig)
- [Vite WASM Plugin](https://vitejs.dev/guide/features.html#webassembly)
- [wasm-bindgen with Vite](https://rustwasm.github.io/wasm-bindgen/reference/deployment.html)

## 🎯 Summary

**Problem:** Tauri CSP blocked WASM execution  
**Solution:** Add `'wasm-unsafe-eval'` + `asset:` protocol + proper Vite config  
**Status:** Should work now! 🚀