# JavaScript Debugging Investigation Summary
## Current Status
JavaScript debugging is entering error state when starting, while Python debugging works perfectly.
## Timeline
- **Commit baecf98**: JavaScript debugging "FULLY WORKING"
- **Commits 749fd55 & c55a566**: Refactored to policy-based architecture
- **Current**: JavaScript debugging broken
## Investigation Findings
### Architecture Analysis
1. ✅ **JsDebugAdapterPolicy exists** with performHandshake implementation
2. ✅ **selectPolicy correctly maps** 'javascript' to JsDebugAdapterPolicy
3. ✅ **performHandshake is called** in session-manager-operations.ts
4. ✅ **Imports are correct** in both files
5. ✅ **js-debug vendor files exist** at the expected location
### What Changed
The refactoring moved JavaScript-specific handshake code from being inline in `session-manager-operations.ts` to the `JsDebugAdapterPolicy.performHandshake()` method.
**Before (working):**
```typescript
// Direct implementation in session-manager-operations.ts
if (session.language === 'javascript') {
// Initialize with supportsStartDebuggingRequest
await pm.sendDapRequest('initialize', {
clientID: 'mcp',
adapterID: 'javascript',
// ... full handshake sequence
});
}
```
**After (broken):**
```typescript
// Delegated to policy
const policy = this.selectPolicy(session.language);
if (policy.performHandshake) {
await policy.performHandshake(context);
}
```
## Hypothesis
The issue might be:
1. The handshake context is not being passed correctly
2. The performHandshake implementation in JsDebugAdapterPolicy has a bug
3. Error handling is swallowing the actual error
4. Timing issue with the policy-based approach
## Next Steps
1. Check the performHandshake implementation in detail
2. Add more logging to see where exactly it fails
3. Test with a minimal JavaScript file
4. Compare the exact DAP message sequence between working and broken versions
