# LLM Streaming Fix

## Problem
Chat messages weren't appearing in the UI because streaming chunks weren't being processed correctly.

## Root Cause
The `MastraAgent` was looking for `chunk.textDelta`, but Mastra's actual chunk structure has the text in `chunk.payload.text`:

```json
{
  "type": "text-delta",
  "runId": "...",
  "from": "AGENT",
  "payload": {
    "id": "msg_...",
    "text": "Hello World"  ← Text is here, not in textDelta
  }
}
```

## Solution
1. **Used proper Mastra SDK types** - Defined interfaces based on `@mastra/core/dist/stream/types.d.ts`:
   - `MastraTextDeltaPayload` with `text: string`
   - `MastraReasoningDeltaPayload` for thinking/reasoning
   - `MastraToolCallPayload` for tool calls

2. **Fixed chunk processing** in `MastraAgent.ts`:
   ```typescript
   case "text-delta": {
     const payload = mastraChunk.payload as unknown as MastraTextDeltaPayload;
     if (payload?.text) {
       yield {
         type: "text-delta",
         payload: { text: payload.text },
         timestamp: new Date().toISOString(),
       };
     }
     break;
   }
   ```

3. **Added support for reasoning-delta** (thinking tokens) and proper tool-call handling

## Test Results
**Before Fix:**
- 📦 Chunks: 1
- 📝 Text: 0 chars ❌
- ⚠️  No text content received

**After Fix:**
- 📦 Chunks: 2-3  
- 📝 Text: 11 chars ✅
- ✅ "Hello World" displayed correctly

## Files Changed
- `src/core/agents/MastraAgent.ts` - Fixed chunk processing with proper types
- `tests/llm-streaming.test.ts` - Added comprehensive streaming tests
- `.env.local` - Created for local API key testing

## Next Steps
- ✅ Streaming works
- 🔄 Need to restart dev server
- 🔧 Fix UI issues (model picker, buttons)
