Module usage_sink 

Process-wide usage event sink (enterprise#17).

usage_meter::record is the single choke-point every measured turn flows through (streaming and non-streaming alike). This module lets a run-mode (the self-hosted gateway) subscribe to that stream without the proxy knowing anything about Postgres: the gateway installs an mpsc sender at startup, and push forwards each finalized RealUsage.

Fail-open by construction (enterprise#12): push never blocks and never errors the request path — when no sink is installed it is a no-op, and when the writer falls behind the event is dropped (counted, visible in logs) rather than back-pressuring live LLM traffic.

Functions

dropped_count

Events dropped because the sink was full/closed (observability, #34).

install

Installs the process-wide sink. First caller wins (one gateway run-mode per process); later calls return false and change nothing.

installed

True once a sink is installed (the gateway run-mode is active).

pending_count

Events currently queued (sent but not yet consumed by the writer). Used by the gateway’s graceful shutdown to drain metering before exit (#51).

push

Forwards one finalized usage record to the sink, if any. Never blocks: on a full or closed channel the event is dropped and counted.