[Exporter.Prometheus] Fix scope metadata

src/OpenTelemetry.Exporter.Prometheus.AspNetCore/CHANGELOG.md

@@ -73,6 +73,17 @@ Notes](../../RELEASENOTES.md).
 * Add Prometheus text fallback `target_info` output as a gauge.
   ([#7238](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7238))
 
+* Emit OpenMetrics scope metadata as a single `otel_scope` metric family with
+  `otel_scope_info` samples instead of repeating metadata for every scope.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
+* Include instrumentation scope metadata on samples using `otel_scope_*` labels
+  including scope version, schema URL, and prefixed scope attributes.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
+* Drop conflicting scope attributes named `name`, `version`, and `schema_url`.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
 ## 1.15.3-beta.1
 
 Released 2026-Apr-21

src/OpenTelemetry.Exporter.Prometheus.HttpListener/CHANGELOG.md

@@ -88,6 +88,17 @@ Notes](../../RELEASENOTES.md).
 * Add Prometheus text fallback `target_info` output as a gauge.
   ([#7238](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7238))
 
+* Emit OpenMetrics scope metadata as a single `otel_scope` metric family with
+  `otel_scope_info` samples instead of repeating metadata for every scope.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
+* Include instrumentation scope metadata on samples using `otel_scope_*` labels
+  including scope version, schema URL, and prefixed scope attributes.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
+* Drop conflicting scope attributes named `name`, `version`, and `schema_url`.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
 ## 1.15.3-beta.1
 
 Released 2026-Apr-21

src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs

@@ -235,6 +235,7 @@ private ExportResult OnCollect(in Batch<Metric> metrics)
     {
         var cursor = 0;
         ref var buffer = ref (this.exporter.OpenMetricsRequested ? ref this.openMetricsBuffer : ref this.plainTextBuffer);
+        var scopeInfoMetadataWritten = false;
 
         try
         {
@@ -251,13 +252,19 @@ private ExportResult OnCollect(in Batch<Metric> metrics)
                         continue;
                     }
 
-                    if (this.scopes.Add(metric.MeterName))
+                    if (this.scopes.Add(PrometheusSerializer.CreateScopeIdentity(metric)))
                     {
                         while (true)
                         {
                             try
                             {
-                                cursor = PrometheusSerializer.WriteScopeInfo(buffer, cursor, metric.MeterName, openMetricsRequested: true);
+                                if (!scopeInfoMetadataWritten)
+                                {
+                                    cursor = PrometheusSerializer.WriteScopeInfoMetadata(buffer, cursor);
+                                    scopeInfoMetadataWritten = true;
+                                }
+
+                                cursor = PrometheusSerializer.WriteScopeInfoMetric(buffer, cursor, metric);
 
                                 break;
                             }
@@ -279,7 +286,7 @@ private ExportResult OnCollect(in Batch<Metric> metrics)
                 }
             }
 
-            var metricStates = this.GetMetricStates(metrics, this.exporter.OpenMetricsRequested);
+            var metricStates = this.GetMetricStates(metrics, this.exporter.OpenMetricsRequested, scopeInfoMetadataWritten);
 
             foreach (var metricState in metricStates)
             {
@@ -401,11 +408,11 @@ private PrometheusMetric GetPrometheusMetric(Metric metric)
         return prometheusMetric;
     }
 
-    private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMetricsRequested)
+    private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMetricsRequested, bool scopeInfoMetadataWritten)
     {
         var precomputedMetricStates = new List<PrecomputedMetricState>();
         var metadataStates = new Dictionary<string, MetadataState>(StringComparer.Ordinal);
-        var droppedMetricNames = new HashSet<string>(StringComparer.Ordinal);
+        HashSet<string>? droppedMetricNames = null;
 
         foreach (var metric in metrics)
         {
@@ -418,6 +425,15 @@ private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMet
             var metadataName = openMetricsRequested ? prometheusMetric.OpenMetricsMetadataName : prometheusMetric.Name;
             precomputedMetricStates.Add(new PrecomputedMetricState(metric, prometheusMetric, metadataName));
 
+            if (openMetricsRequested &&
+                scopeInfoMetadataWritten &&
+                (metadataName == "otel_scope" || metadataName == "otel_scope_info"))
+            {
+                droppedMetricNames ??= new(StringComparer.Ordinal);
+                droppedMetricNames.Add(metadataName);
+                continue;
+            }
+
             if (!metadataStates.TryGetValue(metadataName, out var metadataState))
             {
                 metadataStates[metadataName] = new MetadataState(
@@ -429,6 +445,7 @@ private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMet
 
             if (metadataState.Type != prometheusMetric.Type)
             {
+                droppedMetricNames ??= new(StringComparer.Ordinal);
                 droppedMetricNames.Add(metadataName);
                 PrometheusExporterEventSource.Log.ConflictingType(metadataName, metadataState.Type, prometheusMetric.Type);
             }
@@ -465,7 +482,7 @@ private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMet
 
         foreach (var metricState in precomputedMetricStates)
         {
-            if (droppedMetricNames.Contains(metricState.MetadataName))
+            if (droppedMetricNames?.Contains(metricState.MetadataName) is true)
             {
                 continue;
             }