Sonic Playwright Broker — priority queue and exclusive access broker for Playwright browser automation. FastAPI service issuing session tokens for token-gated browser access. Manages reservation queue (priority + FIFO), overstay watchdog, head-of-queue callbacks. Replaces direct Playwright MCP access. Runs as Docker Compose stack 'sonic-broker-prod' (container, host networking), NOT systemd — the prior execution-standard systemd unit (sonic_broker.service) was decommissioned 2026-08-16: it predated the Docker migration and had been crash-looping (~147k restarts) failing to bind :8099, which the Docker container already held. Container bind-mounts ~/prod/sonic/src/broker into /app/src/broker, so code edits deploy via vivo copy to ironclad prod + a container restart (no image rebuild needed). Compose file: ~/prod/sonic/docker-compose.yml.