Implements structured logging package with LOG_LEVEL/LOG_FORMAT env support, debug level guards for hot paths, enriched error messages with actionable context, and stack trace capture for production debugging. Improves observability and reduces log overhead in high-frequency polling loops.
Replaces immediate polling with queue-based scheduling:
- TaskQueue with min-heap (container/heap) for NextRun-ordered execution
- Worker goroutines that block on WaitNext() until tasks are due
- Tasks only execute when NextRun <= now, respecting adaptive intervals
- Automatic rescheduling after execution via scheduler.BuildPlan
- Queue depth tracking for backpressure-aware interval adjustments
- Upsert semantics for updating scheduled tasks without duplicates
Task 6 of 10 complete (60%). Ready for error/backoff policies.
Adds freshness metadata tracking for all monitored instances:
- StalenessTracker with per-instance last success/error/mutation timestamps
- Change hash detection using SHA1 for detecting data mutations
- Normalized staleness scoring (0-1 scale) based on age vs maxStale
- Integration with PollMetrics for authoritative last-success data
- Wired into all poll functions (PVE/PBS/PMG) via UpdateSuccess/UpdateError
- Connected to scheduler as StalenessSource implementation
Task 4 of 10 complete. Ready for adaptive interval logic.
