stemedb/uat/production-readiness/results/2026-02-05-wal-sync-fix.md

UAT Report: WAL Segment Synchronization Fix

Date: 2026-02-05 Phase/Feature: WAL/IngestWorker synchronization Tester: Claude Code Status: PASS

Summary

Fixed WAL segment size cache bug causing IngestWorker to fail reading newly-written records. All 180+ core tests now pass, and end-to-end pipeline verified working.

Scope

What was tested:

• WAL append and read operations
• IngestWorker record processing
• v1 and v2 signature verification
• End-to-end ingestion pipeline (pharma-ingest)
• Skeptic lens conflict analysis

What was NOT tested:

• Load testing (sustained throughput)
• Crash recovery under load
• Distributed cluster scenarios

Environment

• Rust version: stable (1.x)
• OS: macOS Darwin 23.6.0
• Commit: Working tree (uncommitted fix)

Test Results

WAL Tests (stemedb-wal)

Test	Expected	Actual	Status
test_read_across_segments	Records readable after append	Records readable	PASS
All 40 WAL tests	Pass	40/40 pass	PASS

Ingest Tests (stemedb-ingest)

Test	Expected	Actual	Status
test_ingest_assertion	Process assertion from WAL	Processed successfully	PASS
test_ingest_vote	Process vote from WAL	Processed successfully	PASS
test_crash_recovery_*	Survive crash, no data loss	All recovery tests pass	PASS
test_rejects_invalid_signature	Reject tampered assertion	Rejected correctly	PASS
All 41 ingest tests	Pass	41/41 pass	PASS

End-to-End Pipeline

Test	Expected	Actual	Status
API server startup	Binds to :18180	Started successfully	PASS
pharma-ingest	11 assertions, 0 errors	11/11 ingested	PASS
/v1/health	assertions_count > 0	assertions_count: 38	PASS
/v1/query?subject=Semaglutide	Returns assertions	28 assertions	PASS
/v1/skeptic	Returns conflict analysis	conflict_score: 0.995	PASS

Issues Found

WAL Segment Size Cache Stale

Severity: Critical Status: Fixed

Description: Journal::append() updated current_offset but not the SegmentManager's cached segment size. When Journal::read() tried to read, it used the stale cached size (8 bytes = header only) and rejected reads as "beyond segment size".

Root Cause: SegmentManager only updated segment sizes in open() and refresh(), not after writes.

Fix Applied:

1. Added update_current_segment_size() method to SegmentManager
2. Called it from Journal::append() after each write

Fixes Applied

• crates/stemedb-wal/src/segment.rs: Added update_current_segment_size() method
• crates/stemedb-wal/src/journal.rs: Call update_current_segment_size() after guard.write()

Artifacts

Test output:

stemedb-core:   99/99 pass
stemedb-ingest: 41/41 pass
stemedb-wal:    40/40 pass
Full workspace: 532/534 pass (2 pre-existing failures in aphoria TLS tests)

Skeptic query result (Semaglutide nausea_rate):

{
  "status": "Contested",
  "conflict_score": 0.99540675,
  "claims": [
    {"value": {"type": "Number", "value": 0.25}, "weight_share": 0.54},
    {"value": {"type": "Number", "value": 0.38}, "weight_share": 0.46}
  ]
}

Recommendations

1. Add load testing - Verify sustained write throughput
2. Fix aphoria TLS tests - 2 pre-existing failures in extractors::tls_version::tests
3. Document backup/restore - WAL archival and recovery procedures
4. Add API authentication - Currently no auth on endpoints

Sign-Off

• All critical tests pass
• No blocking issues remain
• Documentation updated (this report)
• Ready for release (pending load testing)