fix: fix metric for hard-limited presets (#18045)

```
// Report a metric only if the preset uses the latest version of the template and the template is not deleted.
// This avoids conflicts between metrics from old and new template versions.
//
// NOTE: Multiple versions of a preset can exist with the same orgName, templateName, and presetName,
// because templates can have multiple versions — or deleted templates can share the same name.
//
// The safest approach is to report the metric only for the latest version of the preset.
// When a new template version is released, the metric for the new preset should overwrite
// the old value in Prometheus.
//
// However, there’s one edge case: if an admin creates a template, it becomes hard-limited,
// then deletes the template and never creates another with the same name,
// the old preset will continue to be reported as hard-limited —
// even though it’s deleted. This will persist until `coderd` is restarted.
```

enterprise/coderd/prebuilds/reconcile.go

@@ -361,15 +361,23 @@ func (c *StoreReconciler) ReconcilePreset(ctx context.Context, ps prebuilds.Pres
 		slog.F("preset_name", ps.Preset.Name),
 	)
 
-	// Report a preset as hard-limited only if all the following conditions are met:
+	// Report a metric only if the preset uses the latest version of the template and the template is not deleted.
-	// - The preset is marked as hard-limited
+	// This avoids conflicts between metrics from old and new template versions.
-	// - The preset is using the active version of its template, and the template has not been deleted
 	//
-	// The second condition is important because a hard-limited preset that has become outdated is no longer relevant.
+	// NOTE: Multiple versions of a preset can exist with the same orgName, templateName, and presetName,
-	// Its associated prebuilt workspaces were likely deleted, and it's not meaningful to continue reporting it
+	// because templates can have multiple versions — or deleted templates can share the same name.
-	// as hard-limited to the admin.
+	//
-	reportAsHardLimited := ps.IsHardLimited && ps.Preset.UsingActiveVersion && !ps.Preset.Deleted
+	// The safest approach is to report the metric only for the latest version of the preset.
-	c.metrics.trackHardLimitedStatus(ps.Preset.OrganizationName, ps.Preset.TemplateName, ps.Preset.Name, reportAsHardLimited)
+	// When a new template version is released, the metric for the new preset should overwrite
+	// the old value in Prometheus.
+	//
+	// However, there’s one edge case: if an admin creates a template, it becomes hard-limited,
+	// then deletes the template and never creates another with the same name,
+	// the old preset will continue to be reported as hard-limited —
+	// even though it’s deleted. This will persist until `coderd` is restarted.
+	if ps.Preset.UsingActiveVersion && !ps.Preset.Deleted {
+		c.metrics.trackHardLimitedStatus(ps.Preset.OrganizationName, ps.Preset.TemplateName, ps.Preset.Name, ps.IsHardLimited)
+	}
 
 	// If the preset reached the hard failure limit for the first time during this iteration:
 	// - Mark it as hard-limited in the database

enterprise/coderd/prebuilds/reconcile_test.go

@@ -1034,7 +1034,8 @@ func TestHardLimitedPresetShouldNotBlockDeletion(t *testing.T) {
 			require.Equal(t, database.WorkspaceTransitionDelete, workspaceBuilds[0].Transition)
 			require.Equal(t, database.WorkspaceTransitionStart, workspaceBuilds[1].Transition)
 
-			// Metric is deleted after preset became outdated.
+			// The metric is still set to 1, even though the preset has become outdated.
+			// This happens because the old value hasn't been overwritten by a newer preset yet.
 			mf, err = registry.Gather()
 			require.NoError(t, err)
 			metric = findMetric(mf, prebuilds.MetricPresetHardLimitedGauge, map[string]string{
@@ -1042,7 +1043,9 @@ func TestHardLimitedPresetShouldNotBlockDeletion(t *testing.T) {
 				"preset_name":   preset.Name,
 				"org_name":      org.Name,
 			})
-			require.Nil(t, metric)
+			require.NotNil(t, metric)
+			require.NotNil(t, metric.GetGauge())
+			require.EqualValues(t, 1, metric.GetGauge().GetValue())
 		})
 	}
 }