- RoutingPolicy.fallback_models: move the cleaning loop into
__init__ (it was unreachable after tier_mode's return, so the
attribute never existed); still parsed but not applied.
- Capability fallback: RoutingDecision gains capability_fallback;
the worker audits worker_capability_fallback when it fires, so
a tier-model rejection followed by a worker-default fallback
is no longer invisible (source stays worker_default, no
model_routing event, so shadow samples are unaffected).
- Registry: resolve_registry_agent checks skills directly
against the loaded definition instead of re-parsing a
hand-built dict, so future fields cannot be silently dropped
the way tool_approvals was in v9.
- Shadow: evaluate_shadow sorts rows earliest-first by
created_at (id tiebreak) when timestamps are present, so
dedup no longer depends on caller row order; the server
path (which strips created_at) is unchanged.
- Gateway: when sub2api fills the default model, the worker
now checks it against the tier's capability requirements
with the same mode semantics as v8 -- shadow only audits,
active fails fast with worker_capability_gate_rejected and
never calls the runner. No worker-default fallback here:
the gateway model is the task's gateway model, falling back
to a worker default would run against the wrong gateway.