diff --git a/prometheus/rules/alerts.yml b/prometheus/rules/alerts.yml
index e5b7f296e7..113f97aa9a 100644
--- a/prometheus/rules/alerts.yml
+++ b/prometheus/rules/alerts.yml
@@ -386,7 +386,7 @@ groups:
         annotations:
           summary: "loopover Orb export error rate above 5%"
           description: "{{ $value | humanizePercentage }} of Orb usage-event exports failed over the last 15m (sustained 15m). Billable events may not be reaching Orb."
-          runbook: "Verify Orb API credentials/connectivity and check level=error logs around orb export. Recorded-but-unexported events (loopover_orb_events_recorded_total vs _exported_total diverging) confirm a stuck exporter."
+          runbook: "Verify Orb API credentials/connectivity and check level=error logs around orb export. A sustained rise in loopover_orb_export_errors_total while loopover_orb_events_exported_total stays flat confirms a stuck exporter."
 
       - alert: LoopoverWebhookEnqueueFailures
         # A webhook accepted by the receiver but not durably queued becomes GitHub
diff --git a/test/unit/alerts-metric-name-references.test.ts b/test/unit/alerts-metric-name-references.test.ts
new file mode 100644
index 0000000000..04034f0a7e
--- /dev/null
+++ b/test/unit/alerts-metric-name-references.test.ts
@@ -0,0 +1,103 @@
+import { readFileSync } from "node:fs";
+import { parse as parseYaml } from "yaml";
+import { describe, expect, it } from "vitest";
+import { DEFAULT_METRIC_META } from "../../src/selfhost/metrics";
+
+// Regression check (#5816): a hand-authored alert annotation (summary/description/runbook) can reference a
+// `loopover_*` metric name that was never registered, or was renamed/removed, without any existing tooling
+// catching it -- scripts/validate-observability-configs.mjs only validates PromQL `expr` syntax, never
+// free-text annotation prose. Scans every `loopover_*`-shaped token in every alert's annotation text and
+// asserts it is either a real registered metric (src/selfhost/metrics.ts's DEFAULT_METRIC_META) or matches
+// one of the documented external-source prefixes (the backup exporter, the opt-in Cloudflare D1 probe, and
+// the miner CLI's own pushed metrics -- none of which register through DEFAULT_METRIC_META).
+
+interface AlertRule {
+  alert: string;
+  annotations?: Record<string, string>;
+}
+interface AlertGroup {
+  name: string;
+  rules: AlertRule[];
+}
+interface AlertsDoc {
+  groups: AlertGroup[];
+}
+
+// Prefixes documented at the top of their respective rule groups in prometheus/rules/alerts.yml as coming
+// from a source other than this process's own in-memory metrics registry.
+const EXTERNAL_METRIC_PREFIXES = ["loopover_backup_", "loopover_d1_", "loopover_miner_"];
+
+const METRIC_TOKEN_PATTERN = /loopover_[a-z0-9_]+\*?/g;
+
+/** Every `loopover_*`-shaped token (a trailing `*` denotes a deliberate label-wildcard family reference, e.g.
+ *  "loopover_jobs_rate_limit_* labels") found across every alert's annotation values. */
+function annotationMetricTokens(doc: AlertsDoc): { alert: string; token: string }[] {
+  const found: { alert: string; token: string }[] = [];
+  for (const group of doc.groups) {
+    for (const rule of group.rules) {
+      for (const text of Object.values(rule.annotations ?? {})) {
+        for (const match of text.matchAll(METRIC_TOKEN_PATTERN)) {
+          found.push({ alert: rule.alert, token: match[0] });
+        }
+      }
+    }
+  }
+  return found;
+}
+
+/** True when `token` resolves to a real metric: an exact match in `registeredNames`, a wildcard prefix
+ *  (trailing `*`) matched by at least one registered name, or one of the documented external prefixes. */
+function isKnownMetricToken(token: string, registeredNames: ReadonlySet<string>): boolean {
+  if (token.endsWith("*")) {
+    const prefix = token.slice(0, -1);
+    return [...registeredNames].some((name) => name.startsWith(prefix));
+  }
+  if (EXTERNAL_METRIC_PREFIXES.some((prefix) => token.startsWith(prefix))) return true;
+  return registeredNames.has(token);
+}
+
+/** Every annotation metric-name reference that resolves to neither a registered metric, a recognized
+ *  wildcard family, nor a documented external prefix -- a dangling/stale reference. */
+function findUnknownMetricReferences(doc: AlertsDoc, registeredNames: ReadonlySet<string>): { alert: string; token: string }[] {
+  return annotationMetricTokens(doc).filter(({ token }) => !isKnownMetricToken(token, registeredNames));
+}
+
+const registeredNames = new Set(DEFAULT_METRIC_META.map(([name]) => name));
+
+describe("alert annotation metric-name references (#5816)", () => {
+  it("references only registered metrics, a recognized wildcard family, or a documented external prefix in the real alerts.yml", () => {
+    const doc = parseYaml(readFileSync("prometheus/rules/alerts.yml", "utf8")) as AlertsDoc;
+    expect(findUnknownMetricReferences(doc, registeredNames)).toEqual([]);
+  });
+
+  it("flags a fabricated, never-registered metric name referenced in an annotation", () => {
+    const fixture: AlertsDoc = {
+      groups: [
+        {
+          name: "fixture-group",
+          rules: [{ alert: "FixtureAlert", annotations: { runbook: "Check loopover_totally_made_up_metric_total for drift." } }],
+        },
+      ],
+    };
+    expect(findUnknownMetricReferences(fixture, registeredNames)).toEqual([{ alert: "FixtureAlert", token: "loopover_totally_made_up_metric_total" }]);
+  });
+
+  it("does not flag a documented external-prefix metric or a wildcard label-family reference", () => {
+    const fixture: AlertsDoc = {
+      groups: [
+        {
+          name: "fixture-group",
+          rules: [
+            {
+              alert: "FixtureExternalAndWildcard",
+              annotations: {
+                runbook: "loopover_backup_files and loopover_d1_database_size_bytes are external. loopover_jobs_rate_limit_* covers the whole family.",
+              },
+            },
+          ],
+        },
+      ],
+    };
+    expect(findUnknownMetricReferences(fixture, registeredNames)).toEqual([]);
+  });
+});