feat(observability): add dashboard panel + alert for review-floor clamps

grafana/dashboards/gittensory.json

@@ -3059,6 +3059,41 @@
           "legendFormat": "skew"
         }
       ]
+    },
+    {
+      "datasource": { "type": "prometheus", "uid": "${DS_PROMETHEUS}" },
+      "fieldConfig": {
+        "defaults": {
+          "color": { "mode": "thresholds" },
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              { "color": "green", "value": null },
+              { "color": "yellow", "value": 1 }
+            ]
+          },
+          "unit": "short"
+        }
+      },
+      "gridPos": { "h": 4, "w": 4, "x": 0, "y": 209 },
+      "id": 161,
+      "options": {
+        "colorMode": "background",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": { "calcs": ["lastNotNull"], "fields": "", "values": false },
+        "textMode": "auto"
+      },
+      "title": "Review-Floor Bypass Attempts (total, #3901)",
+      "type": "stat",
+      "targets": [
+        {
+          "datasource": { "type": "prometheus", "uid": "${DS_PROMETHEUS}" },
+          "expr": "gittensory_ai_review_onmerge_clamped_total or vector(0)",
+          "legendFormat": "clamped"
+        }
+      ]
     }
   ],
   "refresh": "30s",

prometheus/rules/alerts.yml

@@ -474,6 +474,21 @@ groups:
           description: "{{ $value | printf \"%.0f\" }} AI review(s) came back inconclusive over the last 30m (sustained 10m). Dual-AI review is repeatedly failing to produce a usable verdict."
           runbook: "Check provider health and circuit-breaker state (gittensory_ai_provider_failures_total / gittensory_ai_provider_circuit_open_total) and verify AI_PROVIDER credentials are still valid for every configured reviewer."
 
+      - alert: GittensoryAiReviewOnMergeFloorBypassAttempted
+        # A repo's .gittensory.yml tried to loosen the operator's onMerge/combine/reviewer-count floor and
+        # got clamped back to the operator's own configured minimum (#3901). A governance/config signal, not
+        # an operational outage, but same absolute-increase style as GittensoryAiProviderCircuitOpen above:
+        # any occurrence (> 0) over 1h is worth a look, sustained 5m so a single instantaneous blip doesn't
+        # immediately page.
+        expr: increase(gittensory_ai_review_onmerge_clamped_total[1h]) > 0
+        for: 5m
+        labels:
+          severity: warning
+        annotations:
+          summary: "a repo's review-floor clamp fired"
+          description: "{{ $value | printf \"%.0f\" }} onMerge/combine/reviewer-count clamp event(s) over the last 1h — a repo config tried to loosen below the operator's configured floor."
+          runbook: "Check which repo's .gittensory.yml requested the loosened setting (gittensory_ai_review_onmerge_clamped_total is labeled by mode) and confirm whether that repo's floor should be adjusted or the request declined."
+
       - alert: GittensoryAiProviderCircuitOpen
         # A provider's circuit breaker opens after AI_PROVIDER_FAILURE_THRESHOLD consecutive failures and
         # short-circuits further attempts for a cooldown window -- ANY circuit-open event in 15m means that

test/unit/selfhost-grafana-dashboard.test.ts

@@ -104,6 +104,16 @@ describe("Gittensory Self-Host Grafana dashboard", () => {
     expect(targets.some((target) => target.expr === "(gittensory_orb_events_recorded_total or vector(0)) - (gittensory_orb_events_exported_total or vector(0))")).toBe(true);
   });
 
+  it("surfaces the onMerge/combine/reviewer-count floor-clamp counter on a panel and an alert (#3901)", () => {
+    const dashboard = readDashboard(selfhostDashboardPath);
+    const targets = dashboard.panels.flatMap((panel) => panel.targets ?? []);
+    const alerts = readFileSync(selfhostAlertsPath, "utf8");
+
+    expect(targets.some((target) => target.expr === "gittensory_ai_review_onmerge_clamped_total or vector(0)")).toBe(true);
+    expect(alerts).toContain("alert: GittensoryAiReviewOnMergeFloorBypassAttempted");
+    expect(alerts).toContain("expr: increase(gittensory_ai_review_onmerge_clamped_total[1h]) > 0");
+  });
+
   it("keeps rate-limit alerts grouped by the dashboard label dimensions", () => {
     const alerts = readFileSync(selfhostAlertsPath, "utf8");