diff --git a/packages/tfcode/src/provider/sdk/copilot/chat/openai-compatible-chat-language-model.ts b/packages/tfcode/src/provider/sdk/copilot/chat/openai-compatible-chat-language-model.ts
index c85d3f3d1..07e744695 100644
--- a/packages/tfcode/src/provider/sdk/copilot/chat/openai-compatible-chat-language-model.ts
+++ b/packages/tfcode/src/provider/sdk/copilot/chat/openai-compatible-chat-language-model.ts
@@ -228,8 +228,8 @@ export class OpenAICompatibleChatLanguageModel implements LanguageModelV2 {
       })
     }
 
-    // reasoning content (Copilot uses reasoning_text):
-    const reasoning = choice.message.reasoning_text
+    // reasoning content (Copilot uses reasoning_text, ToothFairyAI/DeepSeek use reasoning_content):
+    const reasoning = choice.message.reasoning_text || choice.message.reasoning_content
     if (reasoning != null && reasoning.length > 0) {
       content.push({
         type: "reasoning",
@@ -456,8 +456,8 @@ export class OpenAICompatibleChatLanguageModel implements LanguageModelV2 {
               reasoningOpaque = delta.reasoning_opaque
             }
 
-            // enqueue reasoning before text deltas (Copilot uses reasoning_text):
-            const reasoningContent = delta.reasoning_text
+            // enqueue reasoning before text deltas (Copilot uses reasoning_text, ToothFairyAI/DeepSeek use reasoning_content):
+            const reasoningContent = delta.reasoning_text || delta.reasoning_content
             if (reasoningContent) {
               if (!isActiveReasoning) {
                 controller.enqueue({
@@ -719,6 +719,8 @@ const OpenAICompatibleChatResponseSchema = z.object({
       message: z.object({
         role: z.literal("assistant").nullish(),
         content: z.string().nullish(),
+        // OpenAI-style reasoning content (ToothFairyAI, DeepSeek, etc.)
+        reasoning_content: z.string().nullish(),
         // Copilot-specific reasoning fields
         reasoning_text: z.string().nullish(),
         reasoning_opaque: z.string().nullish(),
@@ -754,6 +756,8 @@ const createOpenAICompatibleChatChunkSchema = <ERROR_SCHEMA extends z.core.$ZodT
             .object({
               role: z.enum(["assistant"]).nullish(),
               content: z.string().nullish(),
+              // OpenAI-style reasoning content (ToothFairyAI, DeepSeek, etc.)
+              reasoning_content: z.string().nullish(),
               // Copilot-specific reasoning fields
               reasoning_text: z.string().nullish(),
               reasoning_opaque: z.string().nullish(),
diff --git a/packages/tfcode/src/provider/transform.ts b/packages/tfcode/src/provider/transform.ts
index 8298351ae..68918ae3b 100644
--- a/packages/tfcode/src/provider/transform.ts
+++ b/packages/tfcode/src/provider/transform.ts
@@ -466,6 +466,7 @@ export namespace ProviderTransform {
       case "venice-ai-sdk-provider":
       // https://docs.venice.ai/overview/guides/reasoning-models#reasoning-effort
       case "@ai-sdk/openai-compatible":
+      case "@toothfairyai/sdk":
         return Object.fromEntries(WIDELY_SUPPORTED_EFFORTS.map((effort) => [effort, { reasoningEffort: effort }]))
 
       case "@ai-sdk/azure":