# =============================================================================
# DESIGN-REFERENCE RULE SET — NOT LOADED BY ANY ALERTMANAGER TODAY.
# =============================================================================
# This file is reference/design config. It is NOT wired into any running
# alerting pipeline:
#   - vmalert (pilot/dev) loads ONLY ops/vmalert/rules/*.yaml
#   - prod CRDs live ONLY in infra/k8s/prom/prometheus-rules/*.yaml
# Nothing mounts or imports tidal/docs/ops/prometheus-alerts.yaml.
# Do not read these as live pager rules.
#
# Provenance: every metric referenced below (tidaldb_health_ok,
# tidaldb_checkpoint_age_seconds, tidaldb_checkpoint_failures_total,
# tidaldb_wal_lag_bytes, tidaldb_signal_hot_entries, tidaldb_degradation_level,
# tidaldb_active_sessions, tidaldb_rate_limited_total,
# tidaldb_tantivy_segment_count, tidaldb_retrieve_latency_us_bucket,
# tidaldb_search_latency_us_bucket) IS really emitted today by
# tidal/src/db/metrics/mod.rs. So these rules are promotable — they
# are not orphaned against phantom metrics.
#
# Promotion path (the right long-term fix — do it deliberately, do NOT
# hand-copy these as live pager rules without the steps below):
#   1. Add a vmalert rule file: ops/vmalert/rules/tidaldb.yaml, translating
#      each rule and stamping the canonical labels every routed rule carries —
#      severity + capability + surface (+ optional component). Map per the
#      canonical severity taxonomy in ops/alerting.md:
#        labels {severity: critical} = pager class (TidalDBDown only here),
#        {severity: warning} = non-paging / business-hours,
#        {severity: info} = pure-FYI.
#      Add capability: tidaldb and a surface label per rule, and a
#      runbook_url annotation:
#        https://github.com/orchard9/tidaldb/blob/main/tidal/docs/runbooks/<area>/<slug>.md
#   2. Add the prod CRD twin: infra/k8s/prom/prometheus-rules/tidaldb.yaml,
#      kept byte-aligned in expr/threshold with the vmalert file.
#   3. Verify the alerts fire against real metrics (scrape tidaldb, force a
#      degraded state) before declaring them on-call-ready.
# Until steps 1–3 land, this file stays a design reference only.
# =============================================================================
groups:
  - name: tidaldb
    interval: 30s
    rules:
      - alert: TidalDBDown
        expr: tidaldb_health_ok == 0
        for: 1m
        labels: { severity: critical }
        annotations:
          summary: "tidalDB is unhealthy"
          description: "tidaldb_health_ok is 0 — database is unhealthy or shut down."

      - alert: TidalDBCheckpointStale
        expr: tidaldb_checkpoint_age_seconds > 300
        for: 2m
        labels: { severity: warning }
        annotations:
          summary: "Signal checkpoint not running"
          description: "{{ $value }}s since last checkpoint (threshold: 300s). Signal durability at risk."

      - alert: TidalDBCheckpointFailures
        expr: increase(tidaldb_checkpoint_failures_total[5m]) > 0
        labels: { severity: warning }
        annotations:
          summary: "Signal checkpoint failures detected"
          description: "Checkpoint failures in last 5m. Check disk space and storage errors."

      - alert: TidalDBWALDiskPressure
        expr: tidaldb_wal_lag_bytes > 1000000000
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "WAL disk usage exceeds 1GB"
          description: "{{ $value | humanize1024 }}B of WAL uncompacted. Compaction may be stuck."

      - alert: TidalDBSignalBacklog
        expr: tidaldb_signal_hot_entries > 4000000
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "Signal ledger over 80% of capacity"
          description: "{{ $value }} hot entries (threshold: 4M / 80% of 5M budget)."

      - alert: TidalDBDegradedRanking
        expr: tidaldb_degradation_level > 0
        for: 2m
        labels: { severity: warning }
        annotations:
          summary: "Ranking quality degraded"
          description: "Degradation level {{ $value }} active. Scale up or reduce load."

      - alert: TidalDBSessionLeak
        # tidaldb_active_sessions is a GAUGE, so rate()/increase() are invalid
        # (those operators only count counter resets). deriv() fits a least-squares
        # slope over the window and is the gauge-correct way to detect sustained
        # growth: > 0.03 sessions/sec is ~> 9 new sessions over a 5m window.
        expr: deriv(tidaldb_active_sessions[5m]) > 0.03 and tidaldb_active_sessions > 100
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "Active session count growing steadily"
          description: "{{ $value }} active sessions and trending up (deriv > 0.03/s). Agents may not be closing sessions."

      - alert: TidalDBHighRateLimiting
        expr: rate(tidaldb_rate_limited_total[5m]) > 100
        for: 5m
        labels: { severity: info }
        annotations:
          summary: "Sustained rate limiting"
          description: "{{ $value }}/s rate-limited writes. Review agent rate limit config."

      - alert: TidalDBTantivySegmentBloat
        expr: tidaldb_tantivy_segment_count > 30
        for: 10m
        labels: { severity: warning }
        annotations:
          summary: "Tantivy segment count elevated"
          description: "{{ $value }} segments (threshold: 30). Text syncer may be stalled."

      - alert: TidalDBSlowRetrieve
        expr: histogram_quantile(0.95, rate(tidaldb_retrieve_latency_us_bucket[5m])) > 500000
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "Retrieve p95 latency exceeds 500ms"
          description: "p95 retrieve latency is {{ $value | humanizeDuration }}. Check signal ledger load and degradation level."

      - alert: TidalDBSlowSearch
        expr: histogram_quantile(0.95, rate(tidaldb_search_latency_us_bucket[5m])) > 1000000
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "Search p95 latency exceeds 1s"
          description: "p95 search latency is {{ $value | humanizeDuration }}. Check Tantivy segment count and ANN index health."