feat(metrics): Add new histograms for chunk latency, results, and sources in AdvisoryAiMetrics

feat(telemetry): Record chunk latency, result count, and source count in AdvisoryAiTelemetry

fix(endpoint): Include telemetry source count in advisory chunks endpoint response

test(metrics): Enhance WebServiceEndpointsTests to validate new metrics for chunk latency, results, and sources

refactor(tests): Update test utilities for Deno language analyzer tests

chore(tests): Add performance tests for AdvisoryGuardrail with scenarios and blocked phrases

docs: Archive Sprint 137 design document for scanner and surface enhancements

src/Concelier/StellaOps.Concelier.WebService/Diagnostics/AdvisoryAiMetrics.cs

@@ -24,6 +24,21 @@ internal static class AdvisoryAiMetrics
         unit: "count",
         description: "Number of advisory chunk segments blocked by guardrails.");
 
+    internal static readonly Histogram<double> ChunkLatencyHistogram = Meter.CreateHistogram<double>(
+        "advisory_ai_chunk_latency_milliseconds",
+        unit: "ms",
+        description: "Elapsed time required to assemble advisory chunks.");
+
+    internal static readonly Histogram<long> ChunkResultHistogram = Meter.CreateHistogram<long>(
+        "advisory_ai_chunk_segments",
+        unit: "chunks",
+        description: "Number of chunk segments returned to the caller per request.");
+
+    internal static readonly Histogram<long> ChunkSourceHistogram = Meter.CreateHistogram<long>(
+        "advisory_ai_chunk_sources",
+        unit: "sources",
+        description: "Number of advisory sources contributing to a chunk response.");
+
     internal static KeyValuePair<string, object?>[] BuildChunkRequestTags(string tenant, string result, bool truncated, bool cacheHit)
         => new[]
         {
@@ -33,6 +48,30 @@ internal static class AdvisoryAiMetrics
             CreateTag("cache", cacheHit ? "hit" : "miss"),
         };
 
+    internal static KeyValuePair<string, object?>[] BuildLatencyTags(string tenant, string result, bool truncated, bool cacheHit)
+        => new[]
+        {
+            CreateTag("tenant", tenant),
+            CreateTag("result", result),
+            CreateTag("truncated", BoolToString(truncated)),
+            CreateTag("cache", cacheHit ? "hit" : "miss"),
+        };
+
+    internal static KeyValuePair<string, object?>[] BuildChunkResultTags(string tenant, string result, bool truncated)
+        => new[]
+        {
+            CreateTag("tenant", tenant),
+            CreateTag("result", result),
+            CreateTag("truncated", BoolToString(truncated)),
+        };
+
+    internal static KeyValuePair<string, object?>[] BuildSourceTags(string tenant, string result)
+        => new[]
+        {
+            CreateTag("tenant", tenant),
+            CreateTag("result", result)
+        };
+
     internal static KeyValuePair<string, object?>[] BuildCacheTags(string tenant, string outcome)
         => new[]
         {

src/Concelier/StellaOps.Concelier.WebService/Program.cs

@@ -913,6 +913,7 @@ var advisoryChunksEndpoint = app.MapGet("/advisories/{advisoryKey}/chunks", asyn
         buildResult.Response.Truncated,
         cacheHit,
         observations.Length,
+        buildResult.Telemetry.SourceCount,
         buildResult.Response.Chunks.Count,
         duration,
         guardrailCounts));

src/Concelier/StellaOps.Concelier.WebService/Services/AdvisoryAiTelemetry.cs

@@ -33,6 +33,18 @@ internal sealed class AdvisoryAiTelemetry : IAdvisoryAiTelemetry
         AdvisoryAiMetrics.ChunkRequestCounter.Add(1,
             AdvisoryAiMetrics.BuildChunkRequestTags(tenant, result, telemetry.Truncated, telemetry.CacheHit));
 
+        AdvisoryAiMetrics.ChunkLatencyHistogram.Record(
+            telemetry.Duration.TotalMilliseconds,
+            AdvisoryAiMetrics.BuildLatencyTags(tenant, result, telemetry.Truncated, telemetry.CacheHit));
+
+        AdvisoryAiMetrics.ChunkResultHistogram.Record(
+            telemetry.ChunkCount,
+            AdvisoryAiMetrics.BuildChunkResultTags(tenant, result, telemetry.Truncated));
+
+        AdvisoryAiMetrics.ChunkSourceHistogram.Record(
+            telemetry.SourceCount,
+            AdvisoryAiMetrics.BuildSourceTags(tenant, result));
+
         if (telemetry.CacheHit)
         {
             AdvisoryAiMetrics.ChunkCacheHitCounter.Add(1,
@@ -56,13 +68,15 @@ internal sealed class AdvisoryAiTelemetry : IAdvisoryAiTelemetry
         }
 
         _logger.LogInformation(
-            "Advisory chunk request for tenant {Tenant} key {Key} returned {Chunks} chunks across {Sources} sources (truncated: {Truncated}, cacheHit: {CacheHit}, durationMs: {Duration}).",
+            "Advisory chunk request for tenant {Tenant} key {Key} returned {Chunks} chunks across {Sources} sources (observationsLoaded: {Observations}, truncated: {Truncated}, cacheHit: {CacheHit}, guardrailBlocks: {GuardrailBlocks}, durationMs: {Duration}).",
             tenant,
             telemetry.AdvisoryKey,
             telemetry.ChunkCount,
+            telemetry.SourceCount,
             telemetry.ObservationCount,
             telemetry.Truncated,
             telemetry.CacheHit,
+            telemetry.TotalGuardrailBlocks,
             telemetry.Duration.TotalMilliseconds.ToString("F2", CultureInfo.InvariantCulture));
     }
 
@@ -118,6 +132,7 @@ internal sealed record AdvisoryAiChunkRequestTelemetry(
     bool Truncated,
     bool CacheHit,
     int ObservationCount,
+    int SourceCount,
     int ChunkCount,
     TimeSpan Duration,
     IReadOnlyDictionary<AdvisoryChunkGuardrailReason, int> GuardrailCounts)