fix(observability): standardize session telemetry attrs (#23213)

packages/opencode/src/session/llm.ts

@@ -74,7 +74,7 @@ const live: Layer.Layer<
         .clone()
         .tag("providerID", input.model.providerID)
         .tag("modelID", input.model.id)
-        .tag("sessionID", input.sessionID)
+        .tag("session.id", input.sessionID)
         .tag("small", (input.small ?? false).toString())
         .tag("agent", input.agent.name)
         .tag("mode", input.agent.mode)
@@ -317,6 +317,18 @@ const live: Layer.Layer<
       const tracer = cfg.experimental?.openTelemetry
         ? Option.getOrUndefined(yield* Effect.serviceOption(OtelTracer.OtelTracer))
         : undefined
+      const telemetryTracer = tracer
+        ? new Proxy(tracer, {
+            get(target, prop, receiver) {
+              if (prop !== "startSpan") return Reflect.get(target, prop, receiver)
+              return (...args: Parameters<typeof target.startSpan>) => {
+                const span = target.startSpan(...args)
+                span.setAttribute("session.id", input.sessionID)
+                return span
+              }
+            },
+          })
+        : undefined
 
       return streamText({
         onError(error) {
@@ -390,7 +402,7 @@ const live: Layer.Layer<
         experimental_telemetry: {
           isEnabled: cfg.experimental?.openTelemetry,
           functionId: "session.llm",
-          tracer,
+          tracer: telemetryTracer,
           metadata: {
             userId: cfg.username ?? "unknown",
             sessionId: input.sessionID,

packages/opencode/src/session/processor.ts

@@ -123,7 +123,7 @@ export const layer: Layer.Layer<
         reasoningMap: {},
       }
       let aborted = false
-      const slog = log.clone().tag("sessionID", input.sessionID).tag("messageID", input.assistantMessage.id)
+      const slog = log.clone().tag("session.id", input.sessionID).tag("messageID", input.assistantMessage.id)
 
       const parse = (e: unknown) =>
         MessageV2.fromError(e, {