Implement full fallback_models support across all integration points:
1. Model Resolution Pipeline (src/shared/model-resolution-pipeline.ts)
- Add userFallbackModels to ModelResolutionRequest
- Process user fallback_models before hardcoded fallback chain
- Support both connected provider and availability checking modes
2. Agent Utils (src/agents/utils.ts)
- Update applyModelResolution to accept userFallbackModels
- Inject fallback_models for all builtin agents (sisyphus, oracle, etc.)
- Support both single string and array formats
3. Model Resolver (src/shared/model-resolver.ts)
- Add userFallbackModels to ExtendedModelResolutionInput type
- Pass through to resolveModelPipeline
4. Delegate Task Executor (src/tools/delegate-task/executor.ts)
- Extract category fallback_models configuration
- Pass to model resolution pipeline
- Register session category for runtime-fallback hook
5. Session Category Registry (src/shared/session-category-registry.ts)
- New module: maps sessionID -> category
- Used by runtime-fallback to lookup category fallback_models
- Auto-cleanup support
6. Runtime Fallback Hook (src/hooks/runtime-fallback/index.ts)
- Check SessionCategoryRegistry first for category fallback_models
- Fallback to agent-level configuration
- Import and use SessionCategoryRegistry
Test Results:
- runtime-fallback: 24/24 tests passing
- model-resolver: 46/46 tests passing
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
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