Function spawn_refresher 

pub fn spawn_refresher(config: LiveConfigHandle)

Spawn the background price refresher, once per process.

No-op when no provider currently sets live_pricing = true: zero network, zero task; the cost path keeps reading an empty snapshot. This cheap pre-check runs before claiming the once-per-process guard, so a later /admin/reload (or a re-start_channels) that newly enables a provider can still start the refresher. Idempotent: a second concurrent caller (e.g. the gateway after the channels supervisor, in a combined process) returns at the guard without building any provider handles.

Every call re-binds CONFIG_HANDLE before anything else, and the running task re-resolves it each cycle, so a daemon reload (which re-instantiates the authority — and its read-only handle — and re-runs both call sites) re-points the refresher at the current published config, and toggling live_pricing on a provider (or changing its model/endpoint) is honored on the next refresh without a restart. Each cycle rebuilds the per-gateway poll set via the normal factory path (reusing each provider’s configured base_url, credentials, and options), fetches one /models per gateway, and fills only the flagged models, falling back to the models.dev catalog for models a gateway doesn’t price (or providers with no HTTP listing, e.g. the kilocli subprocess gateway). A fetch error for one source keeps the previous snapshot rather than regressing good prices to empty; disabling live_pricing on the last flagged provider instead clears the snapshot on the next cycle, so stale prices stop filling after an opt-out.