Explain why two builds differ

Inputs: [BUILD COMMANDS], [MANIFESTS], [ARTIFACT HASHES]. Compare dependency locks, environment, timestamps and generated files. Rank causes by evidence and propose a minimal reproduction. Output: A difference ledger and read-only checks. Check: Each proposed cause has a discriminating test; hashes are not treated as proof of functional difference. If essential information is missing, identify it rather than filling the gap with a guess. Keep environmental differences separate from source changes in the final cause ranking.