## QA Verification Complete - PASSED ✓ **Status**: Implementation verified and working correctly **Test Results**: - ✓ All 177 tests pass - ✓ Code review confirms correct implementation - ✓ Live API test confirms cost data extraction works - ✓ Database verification shows cost values stored correctly **Live Test Evidence**: Query ID: 8391d478-ccfd-47a9-ab92-46ee75eb3b8e - input_tokens_cost: 0.0 - output_tokens_cost: 0.0 - request_cost: 0.005 - api_total_cost: 0.005 **Key Fix**: The implementation now correctly extracts cost data from model_extra['cost'] dictionary in the Perplexity API response, resolving the issue from the previous attempt. **Recommendation**: APPROVED - Ready for production Full QA report: /tmp/qa-PPLX-23.md

## Fix Applied: Cost Extraction Bug **Problem Found**: The code in perplexity_client.py:186-193 was checking for cost fields as direct attributes using hasattr(chunk.usage, 'input_tokens_cost'), but the Perplexity API returns cost data nested in model_extra['cost'] dictionary. **Changes Made** (backend/perplexity_client.py:185-193): - Changed from: hasattr(chunk.usage, 'input_tokens_cost') - Changed to: chunk.usage.model_extra.get('cost', {}) **Verification**: - All 177 tests pass - Live API test confirmed cost data extraction works: - input_tokens_cost: 0.0 - output_tokens_cost: 0.0 - request_cost: 0.005 - api_total_cost: 0.005 **Commit**: be0b19d - merged to main Ready for QA verification.

[QA] Implementation FAILED - Cost data not being extracted from API response **Bug**: The code in perplexity_client.py:186-193 checks for cost fields as direct attributes (hasattr(chunk.usage, 'input_tokens_cost')), but Perplexity API returns them nested in model_extra['cost']. **Evidence**: Live API test shows all cost columns are NULL in database. **Root Cause**: - Current code: hasattr(chunk.usage, 'input_tokens_cost') - Actual structure: chunk.usage.model_extra['cost']['input_tokens_cost'] **Fix Required**: Update perplexity_client.py to extract from model_extra['cost'] dictionary. **Impact**: Feature is completely non-functional. No cost data is being captured. See full QA report: /tmp/qa-PPLX-23.md

## Feature Triage Complete **Status:** NOT IMPLEMENTED - Ready for implementation **Summary:** The feature adds 4 new cost breakdown columns to the api_usage_log table. Research confirmed that the Perplexity API already returns this granular cost data (input_tokens_cost, output_tokens_cost, request_cost, total_cost), but the current implementation doesn't capture it. **Implementation Location:** - New Alembic migration for 4 Float columns - Models, CRUD, schemas updates - perplexity_client.py to extract cost data from API response - routers/queries.py to pass cost data through **Complexity:** LOW - Additive changes only, no breaking changes **Scope:** SMALL - 5-6 files, <100 lines See attached triage report (PPLX-23 Triage Report) for full details including: - Exact code locations to modify - Implementation approach - Edge cases to consider - Testing strategy