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# ADR 0006 evidence assertion provenance

# ADR-0006: Evidence/Assertion model — confirmation never overwrites inference

**Status:** Accepted · 2026-07-14

## Decision

Implements the handoff data model directly:

* `evidence` — typed immutable observations (phrase hit, fingerprint match, label
  GUID, permission exposure, editor context, policy citation, human decision) with
  direction (+/−), weight, provenance kind, acquisition context, versions, and
  bitemporal times.
* `assertions` — versioned claims `(subject, predicate, object)` with status
  (`candidate|superseded|retracted`), calibrated confidence, provenance kind
  (`Observed|RuleDerived|ModelInferred|PolicyDerived|OwnerConfirmed|
  GovernanceValidated|RemediationVerified|Imported`), evidence links, and release/
  config references.
* Owner decisions create **new** `OwnerConfirmed`/corrective assertions linked via
  `confirms_assertion`/`corrects_assertion`/`rejects_assertion`; the original
  model-inferred assertion is preserved (possibly superseded, never mutated) so model
  evaluation against human ground truth stays possible.
* Distinct value states everywhere they matter: `unlabeled`, `unknown`,
  `unsupported`, `inaccessible`, `partial`, `failed` are separate enum values, not
  null-collapsed.

## Consequences

* The review queue, propagation, findings, Analyst, and audit all reference
  assertion/evidence IDs — answers are reproducible to exact versions.
* Storage grows append-mostly; supersession pointers keep "current view" queries
  cheap via partial indexes on `status='candidate'`.