From 383592dfed27fba2df63a728d80d90e1d325b9c2 Mon Sep 17 00:00:00 2001
From: Jeffery Lofoneh Asamani <jefferyasamani7@gmail.com>
Date: Sat, 31 Oct 2026 16:32:08 +0000
Subject: [PATCH] test(sdk-tanstack-ai): cover the onConfig phase guard

Supported engines call onConfig after onStart only before a model call, so
no engine run reaches the guard that skips the other phases. Calling it
directly for each of those phases now shows that none opens an iteration
span. Removing the guard fails every case.
---
 packages/tanstack-ai/tests/middleware.test.ts | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/packages/tanstack-ai/tests/middleware.test.ts b/packages/tanstack-ai/tests/middleware.test.ts
index 20e9a996..37783690 100644
--- a/packages/tanstack-ai/tests/middleware.test.ts
+++ b/packages/tanstack-ai/tests/middleware.test.ts
@@ -868,6 +868,28 @@ test("a real chat() run opens one iteration span per model call", async () => {
   expect(metrics.filter((m) => m.metric === "duration")).toHaveLength(1);
 });
 
+// Supported engines call onConfig after onStart only before a model call, so no engine run reaches
+// the phase guard; this calls it directly.
+test.each(["init", "afterModel", "modelStream", "beforeTools", "afterTools"] as const)(
+  "onConfig for phase %s after onStart opens no iteration span",
+  async (phase) => {
+    const { spanBatches, overrides } = makeCapture();
+    const mw = middleware(overrides);
+    const ctx = makeCtx();
+
+    await mw.onStart?.(ctx);
+    await mw.onConfig?.(ctx, chatConfig());
+    Object.assign(ctx, { phase });
+    await mw.onConfig?.(ctx, chatConfig());
+    await mw.onUsage?.(ctx, { promptTokens: 10, completionTokens: 5, totalTokens: 15 } as never);
+    await mw.onFinish?.(ctx, { finishReason: "stop", duration: 50, content: "done" } as never);
+
+    const iterations = spanBatches[0]!.filter((s) => s.kind === SpanKind.CLIENT);
+    expect(iterations).toHaveLength(1);
+    expect(iterations[0]!.attributes["gen_ai.usage.input_tokens"]).toBe(10);
+  },
+);
+
 test("structured output finalization records a separate iteration span", async () => {
   const { spanBatches, metrics, overrides } = makeCapture();
   const mw = middleware(overrides);