~anthropic/claude-sonnet-latest → B (60:40)

Commit B is a precise, correct bugfix: it moves the zero-ratio guard before ensure_item/voted_pairs.insert so ghost items and phantom voted-pairs no longer pollute reducer state, and it updates the test to assert the corrected invariant. Commit A is a larger feature/refactor (faster scan, ingest replay CLI) that adds useful tooling but is more diffuse, higher risk of new bugs, and less critical than fixing genuine state-corruption in the core reducer.