fix: use lazy attributes in sendTurn metrics to capture resolved provider

The sendTurn method eagerly evaluated input.modelSelection?.provider for
metric attributes before the effect ran, recording the requested provider
instead of the actual routed adapter provider. When modelSelection was
omitted, metrics incorrectly recorded provider as 'unknown'.

This changes sendTurn to use the same mutable variable pattern as all
other provider operations (interruptTurn, respondToRequest, etc.) and
extends WithMetricsOptions.attributes to accept a lazy callback so both
the counter and timer capture the resolved provider after routing.

Author: cursoragent

apps/server/src/observability/Metrics.ts

@@ -91,7 +91,9 @@ export const increment = (
 export interface WithMetricsOptions {
   readonly counter?: Metric.Metric<number, unknown>;
   readonly timer?: Metric.Metric<Duration.Duration, unknown>;
-  readonly attributes?: Readonly<Record<string, unknown>>;
+  readonly attributes?:
+    | Readonly<Record<string, unknown>>
+    | (() => Readonly<Record<string, unknown>>);
   readonly outcomeAttributes?: (
     outcome: ReturnType<typeof outcomeFromExit>,
   ) => Readonly<Record<string, unknown>>;
@@ -105,7 +107,8 @@ const withMetricsImpl = <A, E, R>(
     const startedAt = Date.now();
     const exit = yield* Effect.exit(effect);
     const duration = Duration.millis(Math.max(0, Date.now() - startedAt));
-    const baseAttributes = options.attributes ?? {};
+    const baseAttributes =
+      typeof options.attributes === "function" ? options.attributes() : (options.attributes ?? {});
 
     if (options.timer) {
       yield* Metric.update(

apps/server/src/provider/Layers/ProviderService.ts

@@ -407,12 +407,16 @@ const makeProviderService = Effect.fn("makeProviderService")(function* (
       "provider.interaction_mode": input.interactionMode,
       "provider.attachment_count": input.attachments.length,
     });
+    let metricProvider = "unknown";
+    let metricModel = input.modelSelection?.model;
     return yield* Effect.gen(function* () {
       const routed = yield* resolveRoutableSession({
         threadId: input.threadId,
         operation: "ProviderService.sendTurn",
         allowRecovery: true,
       });
+      metricProvider = routed.adapter.provider;
+      metricModel = input.modelSelection?.model;
       yield* Effect.annotateCurrentSpan({
         "provider.kind": routed.adapter.provider,
         ...(input.modelSelection?.model ? { "provider.model": input.modelSelection.model } : {}),
@@ -442,13 +446,14 @@ const makeProviderService = Effect.fn("makeProviderService")(function* (
       withMetrics({
         counter: providerTurnsTotal,
         timer: providerTurnDuration,
-        attributes: providerTurnMetricAttributes({
-          provider: input.modelSelection?.provider ?? "unknown",
-          model: input.modelSelection?.model,
-          extra: {
-            operation: "send",
-          },
-        }),
+        attributes: () =>
+          providerTurnMetricAttributes({
+            provider: metricProvider,
+            model: metricModel,
+            extra: {
+              operation: "send",
+            },
+          }),
       }),
     );
   });