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ADR-0010: Policy precedence

Status​

Accepted

Context​

Several RoutingPolicy objects may match one request (tenant, agent, path).

Decision​

  • Policies are evaluated in a total order: spec.priority descending, then namespace/name ascending. The first policy whose scope matches wins; policies are never merged.
  • Scope matching uses simple globs: * matches everything, prefix* and *suffix are supported, everything else is exact and case-sensitive. An empty list matches everything.
  • Whether the request is routed at all is decided by the winning policy's match.modelAliases; a non-matching requested model is PASS_THROUGH.
  • The compiler warns when two policies in one namespace share priority and an identical match (the lexicographically smaller name always wins).
  • X-Routed-Policy can select a policy only among those whose scope matches the request (ADR-0007).

Consequences​

  • Explanations name exactly one policy; "why this policy" is answered by ordering alone.

Alternatives considered​

  • Most-specific-match wins: rejected; specificity is ambiguous across tenant, agent and path dimensions, priority is explicit.