ADR A-09: Behaviour selection policy

Status

Accepted

Context

A trigger may make several transitions eligible at once. Behaviour needs a declared selection rule so execution is deterministic and auditable.

Decision

Behaviour declares selection policy explicitly on a transition definition via bhv:selectionPolicy, using mechanism vocabulary rather than implementation-local logic. Baseline policies are:

• bhv:SingleMatch
• bhv:AllMatches
• bhv:PriorityOrdered

When PriorityOrdered is used, transition definitions must also declare one integer bhv:priority.

Consequences

• Ambiguity is visible in authored data rather than hidden in an engine.
• Deterministic selection can be validated structurally.
• Multi-profile conformance can compare outcomes across evaluators.