- Keep this crate a thin composition layer: mount endpoint routers and serve the supplied listener
- Server lifecycle and shared inbound middleware belong here, including client authentication, rate limiting, and request logging
- Endpoint paths, request handling, model resolution, and response encoding belong to the mounted crates. Provider execution belongs to the `inference-<fmt>` crates and `llms`
- Inject shared state and infrastructure. Avoid global runtimes, duplicate client pools, and abstractions for hypothetical endpoint groups
- Test mounting and server lifecycle through public HTTP behavior. Test endpoint semantics in the owning crate

## Redis
- `build_redis` builds the Redis clients once at boot (`src/redis/mod.rs`). Components get a clone as a field, never a per-request extractor or a pool. redis-rs multiplexes one connection per node, so there is no connection pool and pool settings like `max_connections` are accepted and ignored
- Which Redis backs which role mirrors the proxy: coordination is `general_settings.coordination_redis`, else the `cache_params` Redis when `cache: true` and `type: redis`, else `REDIS_*` env. The transaction buffer reuses coordination, else env when `use_redis_transaction_buffer` is on. The response cache gets its own client so large values never queue in front of coordination commands
- `src/redis/layers.rs` is the Rust copy of `_merge_redis_kwargs` in `litellm/_redis.py`, which only this host needs because the Python host merges in Python. It puts the configured kwargs over their `REDIS_*` values and fills the `get_secret` fallbacks from the `SETTINGS` rows in `redis-resolve`, under the same conditions Python reads them, then hands the result to `litellm_redis_resolve::interpret`. Values come from a `SecretSnapshot` filled once at boot, read like `get_secret` (secret manager, then environment, with `true` and `false` read as bools), and the only straight environment read is Azure's `REDIS_USERNAME`
- A surface is a `ConfiguredRedis` constructor: `coordination` for `general_settings.coordination_redis`, which rejects a malformed `port` like the proxy's `CoordinationRedisParams` pydantic model, `cache_params` for `litellm_settings.cache_params`, which drops the cache-only keys and reads the `redis_startup_nodes` alias, and `redis_cache_kwargs` for a `RedisCache.redis_kwargs` dict in the contract tests. A new surface is a new constructor, never a flag
- Nulls depend on the surface. `coordination_redis` drops every null like `model_dump(exclude_none=True)`, `cache_params` keeps a null as an explicit `None` that hides the `REDIS_*` value unless `Cache` or `RedisCache` names that parameter, and `RedisCache.redis_kwargs` keeps every null. A missing `os.environ/` reference is a null, as `load_config` resolves it
- A setting the Rust client cannot honor warns and is dropped, and only a security check it cannot enforce fails boot, per `redis-resolve/AGENTS.md`
- Boot never waits for a configured Redis (clients connect lazily). Only the env-only coordination fallback is pinged, for 2s, and treated as absent when unreachable, as in Python
- `/health/readiness` never touches Redis, matching the proxy