ADR 0005 — Knowledge substrates are mounted, and their contribution is measured

Status: accepted · Date: 2026-09-19 · Sprint: 2 Supersedes: the first draft’s “vendor the CE-RISE models” ADR, which treated one substrate as the architecture.

Context

COMPASS’s symbolic layer fires on 7.96 % of the workload with observed conditional precision 1.000. The precision is the contribution; the coverage is the limitation. Several bodies of structured knowledge could raise coverage — the DPP core ontology and its domain modules, the 17 CE-RISE data models, the PEFDPP graph, and an unseen schema like Open Food Facts — but each raises a different question about whether precision survives.

An architecture that hard-wires one of them cannot answer that question, and an architecture that hard-wires the largest one confuses a substrate with a design.

Decision

SubstrateRegistry mounts substrates. Each declares the subjects it covers, the facts it supplies and the queries it accepts. Crucially it exposes coverage_report(): symbolic fire rate and conditional precision per substrate.

A mode is a named bundle of substrates plus adapters plus a default operating point. “CE-RISE mode” mounts the CE-RISE data models and the PEFDPP graph on top of the Normal set.

CE-RISE model schemas are vendored into schemas/ce-rise/ with source URL, commit SHA and fetch date in VENDOR.md; the application never fetches a schema at runtime. Codeberg is unreachable from the build sandboxes (403 at the egress proxy), and a DOI-archived artifact must validate years later exactly as it did on release day.

Consequences

• “Which knowledge bought which reach” becomes a number in a report.
• The OFF generalisation study runs from the same registry as everything else, rather than a separate script.
• A substrate that raises coverage but drops conditional precision below the published bar is visibly not worth mounting — which is a finding, not a failure.
• Reproducible, offline builds. − Vendored copies go stale; a scheduled job diffs upstream and opens an issue. − One more layer of indirection between a question and the triple that answers it.