Validation gate: external measurement and SaaS product hardening

[uuonnouu]

Independent validation review of main at 2026-08-13.

[IMPLEMENTED]

• Core DEFLATE/STORE compression and SHA-256 round-trip gate exist.
• External measurement engine, provenance records, and comparative benchmark framework exist.
• Documentation and generated benchmark artifacts exist.

[IMPLEMENTATION GAP]

• src/compaction/external_engine.py imports analyze directly but calls analysis.analyze(data). analysis is not defined in the shown implementation, so the external measurement path is not demonstrated runnable from repository evidence.

[TEST GAP]

• Repository tree contains no substantive unit/integration test suite; tests/comparative_benchmark.py is a benchmark harness rather than a test suite.
• Boundary cases are not demonstrated: empty bytes, one byte, tiny payloads, invalid compressed payloads, invalid algorithm names, extreme compression levels, and repeated-run determinism.

[VALIDATION GAP]

• DELIVERY_SUMMARY/README report 5/5 verified measurements and production readiness, but repository evidence supplied here does not independently reproduce those results.
• Throughput is machine-dependent and the documented 50+ MB/s result is only a synthetic benchmark observation, not a general performance guarantee.

[COMPARATIVE BENCHMARK GAP]

• tests/comparative_benchmark.py says it benchmarks external measurements but reconstructs separate synthetic payloads rather than using original measurement bytes. Therefore its comparison is not a direct rerun of the recorded external measurements.
• CANDIDATE_LZ77_PLACEHOLDER is explicitly not an implementation and must not be presented as a real candidate algorithm.

[DOCUMENTATION GAP]

• README contains stale /mnt/data and nested comPaction-api/ paths inconsistent with the repository root layout.
• README uses "verified" and "production-ready" language more broadly than the evidence presently establishes.

NEXT VALIDATION WORK

1. Fix the external engine import/call mismatch.
2. Add executable unit tests for core compression, diagnostics, provenance, and external ingestion.
3. Add adversarial and boundary test vectors with explicit acceptance criteria.
4. Refactor comparative benchmarking to consume actual test payloads and record provenance linking each benchmark to its input hash.
5. Build an interactive downloadable SaaS/local web product that exposes measurement, comparison, provenance, and validation status without overstating claims.

Status: [UNVERIFIED] until executable tests are run against the repository checkout.