Backend toggle now cycles through chat role models by label instead of
cycling service type strings (auto/claude/gemini/local).
- model_registry: get_model_for_slot() — resolves a specific priority
slot without walking the fallback chain
- llm_client: complete() gains slot param; explicit slot selection
dispatches directly to that model with no silent fallback
- routers/chat.py: ChatRequest.slot; GET /backend returns chat_models
[{slot, label, type}] for the UI; _stream_chat uses resolved model
label for the response tag when a slot is pinned
- app.js: toggle loads chat_models from /backend, cycles by label,
sends slot in chat payload; legacy model field removed from payload
- app.js: fix Gap B — agent mode placeholder no longer says "Gemini
tool loop"; now says "orchestrator"
- DESIGN doc: updated to reflect phases 1+2 complete, catalog-as-code
decision, Gap A/B documented, Phase 3 implementation details
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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