Phase 6: Root Cause Discovered - NOT Disk Read Bug
After comprehensive debugging with server-side logging:
What We Found:
✅ Disk read works correctly (reads what exists on disk)
✅ Cache works correctly (caches what was read)
✅ Extraction works correctly (returns what's cached)
❌ DATA IS MISSING from both disk and memory!
The Evidence:
Request offset: 1764
Disk has: 1000-1763 (764 messages)
Memory starts at: 1800
Gap: 1764-1799 (36 messages) ← LOST!
Root Cause:
Buffer flush logic creates GAPS in offset sequence
Messages are lost when flushing from memory to disk
bufferStartOffset jumps (1763 → 1800) instead of incrementing
Changes:
- log_read_stateless.go: Simplified cache extraction to return empty for gaps
- Removed complex invalidation/retry (data genuinely doesn't exist)
Test Results:
Original: 87.9% delivery
Cache invalidation attempt: 73.3% (cache thrashing)
Gap handling: 82.1% (confirms data is missing)
Next: Fix buffer flush logic in log_buffer.go to prevent offset gaps