Exports fleet observability to Prometheus/Grafana (previously JSON-only).
- GET /api/fleet/metrics/prom: global, product-labelled Prometheus exposition
(queue depth, blocked/active, per-stage histogram, factory health/seats/
utilization, active alerts, budget spent/ceiling/projected) plus process-wide
reaper/GC counters and engine circuit-breaker state. Pure renderer
(renderFleetMetricsProm) is unit-tested; route auth accepts a FLEET_METRICS_TOKEN
bearer (scrape path) or an admin JWT — never world-readable by default.
- Infra: add a prometheus container to docker-compose + a platform-service-fleet
scrape job; pin the Prometheus Grafana datasource uid; add a provisioned
"Fleet Overview" dashboard (breakers, dead-letter, stale factories, alerts,
queue depth, utilization, budget burn, reaper rate) with a product template var.
- Document FLEET_METRICS_TOKEN + the fleet feature flags in .env.example.
No default behavior change: the endpoint is additive and the new container is
opt-in via the compose stack.
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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
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