From dd42154e45227955c30e2d4e92f9d548d645ef87 Mon Sep 17 00:00:00 2001
From: Vincent Koc <vincentkoc@ieee.org>
Date: Sat, 4 Apr 2026 02:14:01 +0900
Subject: [PATCH] fix(providers): stop forcing reasoning effort on proxy
 completions

---
 src/agents/openai-completions-compat.ts    | 6 ++++++
 src/agents/openai-transport-stream.test.ts | 6 +++++-
 src/agents/openai-transport-stream.ts      | 3 +--
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/agents/openai-completions-compat.ts b/src/agents/openai-completions-compat.ts
index 903dba6d70d..4500ad3eba1 100644
--- a/src/agents/openai-completions-compat.ts
+++ b/src/agents/openai-completions-compat.ts
@@ -10,6 +10,7 @@ type OpenAICompletionsCompatDefaultsInput = {
 export type OpenAICompletionsCompatDefaults = {
   supportsStore: boolean;
   supportsDeveloperRole: boolean;
+  supportsReasoningEffort: boolean;
   supportsUsageInStreaming: boolean;
   supportsStrictMode: boolean;
 };
@@ -48,6 +49,11 @@ export function resolveOpenAICompletionsCompatDefaults(
     supportsStore:
       !isNonStandard && knownProviderFamily !== "mistral" && !usesExplicitProxyLikeEndpoint,
     supportsDeveloperRole: !isNonStandard && !isMoonshotLike && !usesConfiguredNonOpenAIEndpoint,
+    supportsReasoningEffort:
+      !isZai &&
+      knownProviderFamily !== "mistral" &&
+      endpointClass !== "xai-native" &&
+      !usesExplicitProxyLikeEndpoint,
     supportsUsageInStreaming: !isNonStandard && !usesConfiguredNonOpenAIEndpoint,
     supportsStrictMode: !isZai && !usesConfiguredNonOpenAIEndpoint,
   };
diff --git a/src/agents/openai-transport-stream.test.ts b/src/agents/openai-transport-stream.test.ts
index de089a4c98c..a556752e772 100644
--- a/src/agents/openai-transport-stream.test.ts
+++ b/src/agents/openai-transport-stream.test.ts
@@ -406,15 +406,19 @@ describe("openai transport stream", () => {
           },
         ],
       } as never,
-      undefined,
+      {
+        reasoningEffort: "high",
+      } as never,
     ) as {
       messages?: Array<{ role?: string }>;
+      reasoning_effort?: unknown;
       stream_options?: unknown;
       store?: unknown;
       tools?: Array<{ function?: { strict?: boolean } }>;
     };
 
     expect(params.messages?.[0]).toMatchObject({ role: "system" });
+    expect(params).not.toHaveProperty("reasoning_effort");
     expect(params).not.toHaveProperty("stream_options");
     expect(params).not.toHaveProperty("store");
     expect(params.tools?.[0]?.function).not.toHaveProperty("strict");
diff --git a/src/agents/openai-transport-stream.ts b/src/agents/openai-transport-stream.ts
index b8fe5cc5a1d..666bbf8f827 100644
--- a/src/agents/openai-transport-stream.ts
+++ b/src/agents/openai-transport-stream.ts
@@ -1351,7 +1351,6 @@ function detectCompat(model: OpenAIModeModel) {
   const isZai = endpointClass === "zai-native" || (isDefaultRoute && provider === "zai");
   const useMaxTokens =
     endpointClass === "chutes-native" || (isDefaultRoute && provider === "chutes") || isMistral;
-  const isGrok = endpointClass === "xai-native" || (isDefaultRoute && provider === "xai");
   const isGroq = endpointClass === "groq-native" || (isDefaultRoute && provider === "groq");
   const reasoningEffortMap: Record<string, string> =
     isGroq && model.id === "qwen/qwen3-32b"
@@ -1366,7 +1365,7 @@ function detectCompat(model: OpenAIModeModel) {
   return {
     supportsStore: compatDefaults.supportsStore,
     supportsDeveloperRole: compatDefaults.supportsDeveloperRole,
-    supportsReasoningEffort: !isGrok && !isMistral && !isZai,
+    supportsReasoningEffort: compatDefaults.supportsReasoningEffort,
     reasoningEffortMap,
     supportsUsageInStreaming: compatDefaults.supportsUsageInStreaming,
     maxTokensField: useMaxTokens ? "max_tokens" : "max_completion_tokens",