diff --git a/src/logging/diagnostic-stability.ts b/src/logging/diagnostic-stability.ts
index 50b0357a3e9..b3273b7198d 100644
--- a/src/logging/diagnostic-stability.ts
+++ b/src/logging/diagnostic-stability.ts
@@ -185,6 +185,12 @@ function sanitizeDiagnosticEvent(event: DiagnosticEventPayload): DiagnosticStabi
       record.costUsd = event.costUsd;
       record.durationMs = event.durationMs;
       break;
+    case "context.assembled":
+      record.channel = event.channel;
+      record.provider = event.provider;
+      record.model = event.model;
+      record.count = event.messageCount;
+      break;
     case "webhook.received":
       record.channel = event.channel;
       break;