Fix reasoning token streaming for gpt-5-mini and gpt-5-nano models (#94)

Mark-Life · AlemTuzlak · web-flow · commit 78f15fea74c7 · 2025-12-09T12:05:23.000+01:00
* fix: reasoning token streaming for gpt-5-mini and gpt-5-nano models

* feat: add model-specific reasoning summary types (concise only for computer-use-preview)

---------

Co-authored-by: Alem Tuzlak &lt;t.zlak@hotmail.com&gt;
diff --git a/.changeset/fix-reasoning-streaming.md b/.changeset/fix-reasoning-streaming.md
@@ -0,0 +1,11 @@
+---
+'@tanstack/ai-openai': patch
+---
+
+Fix reasoning token streaming for `gpt-5-mini` and `gpt-5-nano` models
+
+- Added `OpenAIReasoningOptions` to type definitions for `gpt-5-mini` and `gpt-5-nano` models
+- Fixed `summary` option placement in `OpenAIReasoningOptions` (moved inside `reasoning` object to match OpenAI SDK)
+- Added handler for `response.reasoning_summary_text.delta` events to stream reasoning summaries
+- Added model-specific `reasoning.summary` types: `concise` only available for `computer-use-preview`
+- Added `OpenAIReasoningOptionsWithConcise` for `computer-use-preview` model
diff --git a/docs/adapters/openai.md b/docs/adapters/openai.md
@@ -131,7 +131,8 @@ Enable reasoning for models that support it (e.g., GPT-5). This allows the model
 ```typescript
 providerOptions: {
   reasoning: {
-    effort: "medium", // "minimal" | "low" | "medium" | "high"
+    effort: "medium", // "none" | "minimal" | "low" | "medium" | "high"
+    summary: "detailed", // "auto" | "detailed" (optional)
   },
 }
 ```
diff --git a/packages/typescript/ai-openai/src/model-meta.ts b/packages/typescript/ai-openai/src/model-meta.ts
@@ -2,6 +2,7 @@ import type {
   OpenAIBaseOptions,
   OpenAIMetadataOptions,
   OpenAIReasoningOptions,
+  OpenAIReasoningOptionsWithConcise,
   OpenAIStreamingOptions,
   OpenAIStructuredOutputOptions,
   OpenAIToolsOptions,
@@ -198,6 +199,7 @@ const GPT5_MINI = {
   },
 } as const satisfies ModelMeta<
   OpenAIBaseOptions &
+    OpenAIReasoningOptions &
     OpenAIStructuredOutputOptions &
     OpenAIToolsOptions &
     OpenAIStreamingOptions &
@@ -233,6 +235,7 @@ const GPT5_NANO = {
   },
 } as const satisfies ModelMeta<
   OpenAIBaseOptions &
+    OpenAIReasoningOptions &
     OpenAIStructuredOutputOptions &
     OpenAIToolsOptions &
     OpenAIStreamingOptions &
@@ -815,6 +818,7 @@ const COMPUTER_USE_PREVIEW = {
   },
 } as const satisfies ModelMeta<
   OpenAIBaseOptions &
+    OpenAIReasoningOptionsWithConcise &
     OpenAIToolsOptions &
     OpenAIStreamingOptions &
     OpenAIMetadataOptions
@@ -1787,11 +1791,13 @@ export type OpenAIChatModelProviderOptionsByName = {
     OpenAIStreamingOptions &
     OpenAIMetadataOptions
   [GPT5_MINI.name]: OpenAIBaseOptions &
+    OpenAIReasoningOptions &
     OpenAIStructuredOutputOptions &
     OpenAIToolsOptions &
     OpenAIStreamingOptions &
     OpenAIMetadataOptions
   [GPT5_NANO.name]: OpenAIBaseOptions &
+    OpenAIReasoningOptions &
     OpenAIStructuredOutputOptions &
     OpenAIToolsOptions &
     OpenAIStreamingOptions &
@@ -1920,6 +1926,7 @@ export type OpenAIChatModelProviderOptionsByName = {
 
   // Special models
   [COMPUTER_USE_PREVIEW.name]: OpenAIBaseOptions &
+    OpenAIReasoningOptionsWithConcise &
     OpenAIToolsOptions &
     OpenAIStreamingOptions &
     OpenAIMetadataOptions
diff --git a/packages/typescript/ai-openai/src/openai-adapter.ts b/packages/typescript/ai-openai/src/openai-adapter.ts
@@ -343,6 +343,29 @@ export class OpenAI extends BaseAdapter<
           }
         }
 
+        // Handle reasoning summary deltas (when using reasoning.summary option)
+        // response.reasoning_summary_text.delta provides incremental summary updates
+        if (
+          chunk.type === 'response.reasoning_summary_text.delta' &&
+          chunk.delta
+        ) {
+          const summaryDelta =
+            typeof chunk.delta === 'string' ? chunk.delta : ''
+
+          if (summaryDelta) {
+            accumulatedReasoning += summaryDelta
+            hasStreamedReasoningDeltas = true
+            yield {
+              type: 'thinking',
+              id: responseId || generateId(),
+              model: model || options.model,
+              timestamp,
+              delta: summaryDelta,
+              content: accumulatedReasoning,
+            }
+          }
+        }
+
         // handle content_part added events for text, reasoning and refusals
         if (chunk.type === 'response.content_part.added') {
           const contentPart = chunk.part
diff --git a/packages/typescript/ai-openai/src/text/text-provider-options.ts b/packages/typescript/ai-openai/src/text/text-provider-options.ts
@@ -125,6 +125,14 @@ https://platform.openai.com/docs/api-reference/responses/create#responses_create
 }
 
 // Feature fragments that can be stitched per-model
+
+// Shared base types for reasoning options
+type ReasoningEffort = 'none' | 'minimal' | 'low' | 'medium' | 'high'
+type ReasoningSummary = 'auto' | 'detailed'
+
+/**
+ * Reasoning options for most models (excludes 'concise' summary).
+ */
 export interface OpenAIReasoningOptions {
   /**
    * Reasoning controls for models that support it.
@@ -138,13 +146,39 @@ export interface OpenAIReasoningOptions {
      * All models before gpt-5.1 default to medium reasoning effort, and do not support none.
      * The gpt-5-pro model defaults to (and only supports) high reasoning effort.
      */
-    effort?: 'none' | 'minimal' | 'low' | 'medium' | 'high'
+    effort?: ReasoningEffort
+    /**
+     * A summary of the reasoning performed by the model. This can be useful for debugging and understanding the model's reasoning process.
+     * https://platform.openai.com/docs/api-reference/responses/create#responses_create-reasoning-summary
+     */
+    summary?: ReasoningSummary
   }
+}
+
+/**
+ * Reasoning options for computer-use-preview model (includes 'concise' summary).
+ */
+export interface OpenAIReasoningOptionsWithConcise {
   /**
-   * A summary of the reasoning performed by the model. This can be useful for debugging and understanding the model's reasoning process
-   * https://platform.openai.com/docs/api-reference/responses/create#responses_create-reasoning-summary
+   * Reasoning controls for models that support it.
+   * Lets you guide how much chain-of-thought computation to spend.
+   * https://platform.openai.com/docs/api-reference/responses/create#responses_create-reasoning
+   * https://platform.openai.com/docs/guides/reasoning
    */
-  summary?: 'auto' | 'concise' | 'detailed'
+  reasoning?: {
+    /**
+     * gpt-5.1 defaults to none, which does not perform reasoning. The supported reasoning values for gpt-5.1 are none, low, medium, and high. Tool calls are supported for all reasoning values in gpt-5.1.
+     * All models before gpt-5.1 default to medium reasoning effort, and do not support none.
+     * The gpt-5-pro model defaults to (and only supports) high reasoning effort.
+     */
+    effort?: ReasoningEffort
+    /**
+     * A summary of the reasoning performed by the model. This can be useful for debugging and understanding the model's reasoning process.
+     * `concise` is only supported for `computer-use-preview` models.
+     * https://platform.openai.com/docs/api-reference/responses/create#responses_create-reasoning-summary
+     */
+    summary?: ReasoningSummary | 'concise'
+  }
 }
 
 export interface OpenAIStructuredOutputOptions {
diff --git a/packages/typescript/ai-openai/tests/model-meta.test.ts b/packages/typescript/ai-openai/tests/model-meta.test.ts
@@ -6,6 +6,7 @@ import type {
 import type {
   OpenAIBaseOptions,
   OpenAIReasoningOptions,
+  OpenAIReasoningOptionsWithConcise,
   OpenAIStructuredOutputOptions,
   OpenAIToolsOptions,
   OpenAIStreamingOptions,
@@ -111,12 +112,12 @@ describe('OpenAI Chat Model Provider Options Type Assertions', () => {
     })
   })
 
-  describe('Models WITH structured output AND tools but WITHOUT reasoning (Standard)', () => {
-    it('gpt-5-mini should have structured output and tools but NOT reasoning', () => {
+  describe('Models WITH reasoning AND structured output AND tools (gpt-5-mini/nano)', () => {
+    it('gpt-5-mini should have reasoning, structured output and tools', () => {
       type Options = OpenAIChatModelProviderOptionsByName['gpt-5-mini']
 
-      // Should NOT have reasoning options
-      expectTypeOf<Options>().not.toExtend<OpenAIReasoningOptions>()
+      // Should have reasoning options
+      expectTypeOf<Options>().toExtend<OpenAIReasoningOptions>()
 
       // Should have structured output options
       expectTypeOf<Options>().toExtend<OpenAIStructuredOutputOptions>()
@@ -131,16 +132,18 @@ describe('OpenAI Chat Model Provider Options Type Assertions', () => {
       expectTypeOf<Options>().toExtend<BaseOptions>()
     })
 
-    it('gpt-5-nano should have structured output and tools but NOT reasoning', () => {
+    it('gpt-5-nano should have reasoning, structured output and tools', () => {
       type Options = OpenAIChatModelProviderOptionsByName['gpt-5-nano']
 
-      expectTypeOf<Options>().not.toExtend<OpenAIReasoningOptions>()
+      expectTypeOf<Options>().toExtend<OpenAIReasoningOptions>()
       expectTypeOf<Options>().toExtend<OpenAIStructuredOutputOptions>()
       expectTypeOf<Options>().toExtend<OpenAIToolsOptions>()
       expectTypeOf<Options>().toExtend<OpenAIStreamingOptions>()
       expectTypeOf<Options>().toExtend<BaseOptions>()
     })
+  })
 
+  describe('Models WITH structured output AND tools but WITHOUT reasoning (Standard)', () => {
     it('gpt-5-codex should have structured output and tools but NOT reasoning', () => {
       type Options = OpenAIChatModelProviderOptionsByName['gpt-5-codex']
 
@@ -439,11 +442,12 @@ describe('OpenAI Chat Model Provider Options Type Assertions', () => {
       expectTypeOf<Options>().toExtend<BaseOptions>()
     })
 
-    it('computer-use-preview should have tools but NOT structured output', () => {
+    it('computer-use-preview should have tools and reasoning with concise but NOT structured output', () => {
       type Options =
         OpenAIChatModelProviderOptionsByName['computer-use-preview']
 
-      expectTypeOf<Options>().not.toExtend<OpenAIReasoningOptions>()
+      // Should have reasoning options with 'concise' summary support
+      expectTypeOf<Options>().toExtend<OpenAIReasoningOptionsWithConcise>()
       expectTypeOf<Options>().not.toExtend<OpenAIStructuredOutputOptions>()
       expectTypeOf<Options>().toExtend<OpenAIToolsOptions>()
       expectTypeOf<Options>().toExtend<OpenAIStreamingOptions>()
@@ -698,13 +702,16 @@ describe('OpenAI Chat Model Provider Options Type Assertions', () => {
       >().toExtend<FullFeaturedOptions>()
     })
 
-    it('standard models should NOT extend reasoning options but should extend structured output and tools', () => {
+    it('gpt-5-mini and gpt-5-nano should extend FullFeaturedOptions (reasoning + structured output + tools)', () => {
       expectTypeOf<
         OpenAIChatModelProviderOptionsByName['gpt-5-mini']
-      >().toExtend<StandardOptions>()
+      >().toExtend<FullFeaturedOptions>()
       expectTypeOf<
         OpenAIChatModelProviderOptionsByName['gpt-5-nano']
-      >().toExtend<StandardOptions>()
+      >().toExtend<FullFeaturedOptions>()
+    })
+
+    it('standard models should NOT extend reasoning options but should extend structured output and tools', () => {
       expectTypeOf<
         OpenAIChatModelProviderOptionsByName['gpt-4.1']
       >().toExtend<StandardOptions>()
@@ -719,9 +726,6 @@ describe('OpenAI Chat Model Provider Options Type Assertions', () => {
       >().toExtend<StandardOptions>()
 
       // Verify these do NOT extend reasoning options (discrimination already tested above)
-      expectTypeOf<
-        OpenAIChatModelProviderOptionsByName['gpt-5-mini']
-      >().not.toExtend<OpenAIReasoningOptions>()
       expectTypeOf<
         OpenAIChatModelProviderOptionsByName['gpt-4.1']
       >().not.toExtend<OpenAIReasoningOptions>()
