In-memory ETS-backed CouncilEx.Reliability store.

Tracks per-member outcome counts bucketed by query feature digest. Score = beta-distribution mean over (successes, failures) per bucket: (α + 1) / (α + β + 2). Cold-start (no record) → nil, not 0.5, so callers can distinguish "no data" from "definitely uncertain".

Feature digest

query_features is hashed with :erlang.phash2/1 to a single bucket key. Pass features that capture similarity:

%{topic: "code_review", length_bucket: :long, language: :elixir}

Identical maps land in the same bucket. Map keys are sorted before hashing, so key order doesn't matter.

Limitations

• No semantic similarity — exact-match buckets only. For nearest- neighbour over embeddings, plug a different store.
• In-memory only. Wipe on BEAM restart.
• Not cluster-aware. Each node has its own table.

Setup

Optional supervised init via your application:

children = [
  CouncilEx.Reliability.ETS
]

Or call init/0 lazily — every public function does this on first use.