- Resolves model from OLLIE_TIER_{WORKER|EXPERT}_{backend}
- Falls back to legacy OLLIE_CASCADE_MODEL/OLLIE_ESCALATE_MODEL
- --backend flag lets orchestrator pick a different backend
- Inherits parent session's backend by default
- OLLIE_ENABLED_BACKENDS documents available backends
- README updated with tier config examples
- route --tier=worker (default): cheap model for scoped subtasks
- route --tier=expert: strong model for complex reasoning
- Orchestrator now uses route instead of cascade
- Unified prompt and callback contract for both tiers
- cascade/escalate remain available for other agents