# Visualization Layout Test Report

**Date**: December 6, 2025
**Test URL**: http://localhost:8080
**Browser**: Safari (macOS)
**Tester**: Web QA Agent

## Executive Summary

**CRITICAL BUG FOUND**: The visualization fails to load entirely due to a JSON parsing error. The initial view layout cannot be tested because the application is stuck in a loading state.

**Status**: ❌ FAILED - Cannot verify horizontal vs vertical layout due to data loading failure

## Test Objective

To verify that the initial view displays nodes in a VERTICAL layout (top to bottom) rather than HORIZONTAL layout (left to right).

## Test Results

### Phase 1: Server Startup ✅

- Server started successfully on port 8080
- Graph data copied to visualization directory
- File size: 6.3MB (6,354,265 bytes)
- JSON structure appears valid (nodes and edges present)

### Phase 2: Page Load ❌

**Issue**: Page stuck on "Loading graph data..." indefinitely

**Observations**:
1. Page loads with loading indicator visible
2. After 60+ seconds, page still shows "Loading graph data..."
3. No visualization rendered
4. No nodes visible (cannot test vertical vs horizontal layout)

### Phase 3: Console Errors ❌

**Critical Error Found**:
```
SyntaxError: Unexpected EOF
```

**Location**: Browser console (Safari)

**Root Cause Analysis**:
The error "Unexpected EOF" (End Of File) suggests one of the following:
1. JSON file transfer is incomplete or interrupted
2. JSON parsing fails due to file size (6.3MB is very large for browser JSON.parse())
3. Browser memory limit reached during parsing
4. Network timeout during fetch

### Phase 4: Network Analysis

**CORS Test Results**:
When testing cross-origin loading from localhost:8081 to localhost:8080:
- ❌ CORS errors detected
- "Origin http://localhost:8081 is not allowed by Access-Control-Allow-Origin"
- "Fetch API cannot load http://localhost:8080/chunk-graph.json due to access control checks"

**Note**: Same-origin loading (localhost:8080 to localhost:8080) should not have CORS issues, but JSON parsing still fails.

## Evidence

### Screenshots

1. **Initial View** (`initial_view_layout.png`):
   - Status: Loading indicator visible
   - Graph area: Empty (dark/black)
   - No nodes rendered

2. **Console Check** (`console_check.png`):
   - Error: "SyntaxError: Unexpected EOF"
   - Status: Loading state persists after 60+ seconds

3. **Final View** (`final_view.png`):
   - Status: Still loading after 2+ minutes
   - No change from initial state

4. **JSON Parse Test** (`json_parse_test.png`):
   - Isolated test shows CORS errors when cross-origin
   - Confirms fetch() is executing but parsing fails

### Console Output

```
SyntaxError: Unexpected EOF
[localhost:8080]
```

## Cannot Test: Layout Orientation

**Expected Test**:
- ✅ Verify nodes are arranged vertically (top to bottom)
- ✅ Verify nodes are alphabetically sorted
- ✅ Verify no edges visible in root view
- ✅ Verify nodes are unconnected

**Actual Result**:
- ❌ Cannot test - no nodes rendered
- ❌ Cannot verify layout orientation
- ❌ Cannot verify sorting
- ❌ Cannot verify edge visibility

## Root Cause Hypothesis

### Primary Suspect: Large JSON File Size

**Evidence**:
- JSON file is 6.3MB
- Browser must parse entire file in memory
- Safari may have stricter memory limits than other browsers
- "Unexpected EOF" suggests parsing failure, not network failure

**Recommendation**: Implement streaming JSON loading or chunked data transfer

### Secondary Suspects

1. **Network Timeout**:
   - 6.3MB file may take too long to transfer on some connections
   - No progress indicator for transfer vs parsing

2. **JSON Structure Issue**:
   - Possible malformed JSON that passes curl validation but fails browser parsing
   - Large nested structures may exceed parser limits

3. **Browser Memory Limit**:
   - Safari on macOS may have stricter memory limits
   - JSON.parse() creates entire object tree in memory

## Recommendations

### Immediate Actions

1. **Implement Streaming JSON Load**:
   ```javascript
   // Use streaming fetch with progress
   const response = await fetch('chunk-graph.json');
   const reader = response.body.getReader();
   const contentLength = +response.headers.get('Content-Length');

   let receivedLength = 0;
   let chunks = [];

   while(true) {
       const {done, value} = await reader.read();
       if (done) break;

       chunks.push(value);
       receivedLength += value.length;

       // Update progress indicator
       const percent = (receivedLength / contentLength) * 100;
       console.log(`Received ${percent.toFixed(0)}%`);
   }

   const chunksAll = new Uint8Array(receivedLength);
   let position = 0;
   for(let chunk of chunks) {
       chunksAll.set(chunk, position);
       position += chunk.length;
   }

   const text = new TextDecoder("utf-8").decode(chunksAll);
   const data = JSON.parse(text);
   ```

2. **Add Progress Indicators**:
   - Show transfer progress (0-50%)
   - Show parsing progress (50-100%)
   - Distinguish between network and parsing phases

3. **Implement Data Chunking**:
   - Split large JSON into smaller files
   - Load nodes first, edges separately
   - Progressive rendering as data loads

4. **Add Error Handling**:
   - Catch JSON parsing errors specifically
   - Display user-friendly error messages
   - Provide fallback options (download JSON, use smaller dataset)

### Testing Improvements

1. **Test with Smaller Dataset**:
   - Create test with 100 nodes, 200 edges
   - Verify core functionality works
   - Incrementally increase size

2. **Add Browser Compatibility Tests**:
   - Test in Chrome, Firefox, Edge
   - Compare memory usage and parsing speed
   - Document browser-specific issues

3. **Performance Monitoring**:
   - Add timing metrics for fetch vs parse
   - Monitor memory usage during load
   - Set reasonable timeouts with user feedback

## Impact Assessment

**Severity**: CRITICAL
**Priority**: P0 (Blocks all visualization testing)
**User Impact**: HIGH (Visualization is completely unusable)

**Affected Features**:
- ❌ Initial view layout (cannot test)
- ❌ Node interaction (cannot test)
- ❌ Navigation (cannot test)
- ❌ Search functionality (cannot test)
- ❌ All visualization features (blocked by loading failure)

## Next Steps

1. **Development Team**:
   - Implement streaming JSON load with progress indicators
   - Add chunked data transfer option
   - Improve error handling and user feedback

2. **QA Team**:
   - Cannot proceed with layout testing until loading issue is resolved
   - Prepare test cases for streaming implementation
   - Create performance benchmarks for data loading

3. **Product Team**:
   - Consider maximum supported codebase size
   - Document performance requirements
   - Evaluate need for server-side pagination

## Technical Details

### Test Environment

- **Server**: Python HTTP server (via mcp-vector-search visualize serve)
- **Port**: 8080
- **Browser**: Safari (macOS 14.x)
- **JSON Size**: 6.3MB
- **Node Count**: Unknown (not loaded)
- **Edge Count**: Unknown (not loaded)

### Files Tested

- `/chunk-graph.json` (6,354,265 bytes)
- Visualization HTML (907 lines)
- D3.js library (loaded successfully)

### Network Conditions

- Localhost (no network latency)
- File accessible via curl
- JSON structure valid when tested with curl

## Conclusion

**The initial layout orientation (vertical vs horizontal) CANNOT be verified** because the visualization fails to load data entirely. The "SyntaxError: Unexpected EOF" indicates a JSON parsing failure, likely due to the large file size (6.3MB) exceeding browser memory or parsing limits.

**Immediate action required** to implement streaming JSON loading or data chunking before any layout testing can proceed.

---

**Report Status**: Complete
**Follow-up Required**: Yes - Development fix needed before testing can continue
