Per DESIGN-a2a-agents.md v2.1 §2-3b: models are the scarce queued
resource, version-controlled here rather than hardcoded in callers.
- model-registry.yaml: kimi (main reasoning, quota-gated), local-small
(ollama/gemma3:4b, always-on cheap tier), bge-m3 (embedder + routing
classifier, never-evict), tei-reranker (never-evict, interactive-
critical), paid-fallback (metered, opt-in only, unreachable by
default via empty routing.metered_opt_in). GPU residency policy
carries the never-evict set, co-residency groups, and measured
baseline (bge-m3+gemma3:4b+tei-reranker ~6.2/8GB on the GTX 1070).
- model_registry.py: resolve(tier) picks an available model without
the caller naming one, gated so a metered model is only reachable
with both allow_metered=True and an opted-in virtual key;
to_probe_config() bridges registry quota data into kb_worker.py's
existing Probe classes (no duplicated probe logic); preload_check()
expresses the §3b pre-load VRAM check purely from registry data.
Gap noted for follow-up: bge-m3 has no litellm-config.yaml model_list
entry yet (embedder there still points at ollama/nomic-embed-text on
a different port) — out of scope here, registry documents it as-is.
