# Edge Runtime Compatibility Fix - Final Solution

## Problem Resolved

The audit logging system was causing "Edge runtime does not support Node.js 'fs' module" errors because the `better-sqlite3` database module was being loaded in Edge Runtime contexts through static imports.

## Root Cause

The middleware imports `auth.js` → which imported `auditLog.js` → which had a static import of `db.js` → which imports `better-sqlite3`. This caused the entire SQLite module to be loaded even in Edge Runtime where it's not supported.

## Final Solution

### 1. Created Safe Audit Logging Module

**File: `src/lib/auditLogSafe.js`**

This module provides:

- ✅ **No static database imports** - completely safe for Edge Runtime
- ✅ **Runtime detection** - automatically detects Edge vs Node.js
- ✅ **Graceful fallbacks** - console logging in Edge, database in Node.js
- ✅ **Constants always available** - `AUDIT_ACTIONS` and `RESOURCE_TYPES`
- ✅ **Async/await support** - works with modern API patterns

```javascript
// Safe import that never causes Edge Runtime errors
import {
	logAuditEventSafe,
	AUDIT_ACTIONS,
	RESOURCE_TYPES,
} from "./auditLogSafe.js";

// Works in any runtime
await logAuditEventSafe({
	action: AUDIT_ACTIONS.LOGIN,
	userId: "user123",
	resourceType: RESOURCE_TYPES.SESSION,
});
```

### 2. Updated All Imports

**Files Updated:**

- `src/lib/auth.js` - Authentication logging
- `src/app/api/projects/route.js` - Project operations
- `src/app/api/projects/[id]/route.js` - Individual project operations
- `src/app/api/notes/route.js` - Note operations

**Before:**

```javascript
import { logApiAction, AUDIT_ACTIONS } from "@/lib/auditLog.js"; // ❌ Causes Edge Runtime errors
```

**After:**

```javascript
import { logApiActionSafe, AUDIT_ACTIONS } from "@/lib/auditLogSafe.js"; // ✅ Edge Runtime safe
```

### 3. Runtime Behavior

#### Edge Runtime

- **Detection**: Automatic via `typeof EdgeRuntime !== 'undefined'`
- **Logging**: Console output only
- **Performance**: Zero database overhead
- **Errors**: None - completely safe

#### Node.js Runtime

- **Detection**: Automatic fallback when Edge Runtime not detected
- **Logging**: Full database functionality via dynamic import
- **Performance**: Full audit trail with database persistence
- **Errors**: Graceful handling with console fallback

### 4. Migration Pattern

The safe module uses a smart delegation pattern:

```javascript
// In Edge Runtime: Console logging only
console.log(`[Audit] ${action} by user ${userId}`);

// In Node.js Runtime: Try database, fallback to console
try {
	const auditModule = await import("./auditLog.js");
	auditModule.logAuditEvent({ ...params });
} catch (dbError) {
	console.log("[Audit] Database logging failed, using console fallback");
}
```

## Files Structure

```
src/lib/
├── auditLog.js          # Original - Node.js only (database operations)
├── auditLogSafe.js      # New - Universal (Edge + Node.js compatible)
├── auditLogEdge.js      # Alternative - Edge-specific with API calls
└── auth.js              # Updated to use safe imports
```

## Testing

Run the compatibility test:

```bash
node test-safe-audit-logging.mjs
```

**Expected Output:**

```
✅ Safe module imported successfully
✅ Edge Runtime logging successful (console only)
✅ Node.js Runtime logging successful (database + console)
✅ Constants accessible
```

## Verification Checklist

✅ **No more Edge Runtime errors**  
✅ **Middleware works without database dependencies**  
✅ **Authentication logging works in all contexts**  
✅ **API routes maintain full audit functionality**  
✅ **Constants available everywhere**  
✅ **Graceful degradation in Edge Runtime**  
✅ **Full functionality in Node.js Runtime**

## Performance Impact

- **Edge Runtime**: Minimal - only console logging
- **Node.js Runtime**: Same as before - full database operations
- **Import cost**: Near zero - no static database imports
- **Memory usage**: Significantly reduced in Edge Runtime

## Migration Guide

To update existing code:

1. **Replace imports:**

   ```javascript
   // Old
   import { logApiAction } from "@/lib/auditLog.js";

   // New
   import { logApiActionSafe } from "@/lib/auditLogSafe.js";
   ```

2. **Update function calls:**

   ```javascript
   // Old
   logApiAction(req, action, type, id, session, details);

   // New
   await logApiActionSafe(req, action, type, id, session, details);
   ```

3. **Add runtime exports** (for API routes):
   ```javascript
   export const runtime = "nodejs"; // For database-heavy routes
   ```

## Best Practices Applied

1. **Separation of Concerns**: Safe module for universal use, full module for Node.js
2. **Dynamic Imports**: Database modules loaded only when needed
3. **Runtime Detection**: Automatic environment detection
4. **Graceful Degradation**: Meaningful fallbacks in constrained environments
5. **Error Isolation**: Audit failures don't break main application flow

The application now handles both Edge and Node.js runtimes seamlessly with zero Edge Runtime errors! 🎉