fix(providers): support OpenAI models requiring max_completion_tokens (#2251)

packages/stage-ui/src/libs/providers/providers/openai/index.ts

@@ -62,6 +62,7 @@ export const providerOpenAI = defineProvider<OpenAICompatibleConfig>({
   validators: {
     ...createOpenAICompatibleValidators({
       checks: [ProviderValidationCheck.Connectivity, ProviderValidationCheck.ModelList, ProviderValidationCheck.ChatCompletions],
+      chatCompletionTokenParameter: 'max_completion_tokens',
     }),
   },
 })

packages/stage-ui/src/libs/providers/validators/openai-compatible.test.ts

@@ -4,6 +4,7 @@ import type { ProviderExtraMethods, ProviderInstance } from '../types'
 
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
+import { providerOpenAI } from '../providers/openai'
 import { ProviderValidationCheck } from '../types'
 import { createOpenAICompatibleValidators } from './openai-compatible'
 
@@ -34,10 +35,10 @@ async function getProviderValidators(options?: Parameters<typeof createOpenAICom
 interface TestConfig { apiKey?: string, baseUrl?: string }
 
 describe('createOpenAICompatibleValidators', () => {
-  const config: TestConfig = {
+  const config = {
     apiKey: 'test-key',
     baseUrl: 'https://example.com/v1/',
-  }
+  } satisfies TestConfig
   const provider: ProviderInstance = {
     model: () => ({
       apiKey: config.apiKey,
@@ -143,6 +144,7 @@ describe('createOpenAICompatibleValidators', () => {
     expect(result.valid).toBe(true)
     expect(generateTextMock).toHaveBeenCalledWith(expect.objectContaining({
       model: 'seed-2-0-pro-260328',
+      max_tokens: 16,
     }))
   })
 
@@ -171,4 +173,42 @@ describe('createOpenAICompatibleValidators', () => {
       max_tokens: 16,
     }))
   })
+
+  it('uses max_completion_tokens when the provider requires the newer parameter', async () => {
+    listModelsMock.mockResolvedValue([
+      { id: 'gpt-5' },
+    ])
+
+    const [, chatValidator] = await getProviderValidators({
+      checks: [ProviderValidationCheck.Connectivity, ProviderValidationCheck.ChatCompletions],
+      chatCompletionTokenParameter: 'max_completion_tokens',
+    })
+
+    const result = await chatValidator.validator(config, provider, providerExtra, { t: mockT })
+
+    expect(result.valid).toBe(true)
+    expect(generateTextMock).toHaveBeenCalledWith(expect.objectContaining({
+      model: 'gpt-5',
+      max_completion_tokens: 16,
+    }))
+    expect(generateTextMock.mock.calls[0][0]).not.toHaveProperty('max_tokens')
+  })
+
+  it('configures the OpenAI provider validation with max_completion_tokens', async () => {
+    listModelsMock.mockResolvedValue([
+      { id: 'gpt-5' },
+    ])
+
+    const validators = await Promise.all((providerOpenAI.validators?.validateProvider || []).map(create => create({ t: mockT })))
+    const chatValidator = validators.find(validator => validator.id === 'openai-compatible:check-chat-completions')
+
+    expect(chatValidator).toBeDefined()
+    const result = await chatValidator!.validator(config, provider, providerExtra, { t: mockT })
+
+    expect(result.valid).toBe(true)
+    expect(generateTextMock).toHaveBeenCalledWith(expect.objectContaining({
+      max_completion_tokens: 16,
+    }))
+    expect(generateTextMock.mock.calls[0][0]).not.toHaveProperty('max_tokens')
+  })
 })

packages/stage-ui/src/libs/providers/validators/openai-compatible.ts

@@ -22,6 +22,7 @@ interface OpenAICompatibleValidationOptions<TConfig extends { apiKey?: string, b
   skipApiKeyCheck?: boolean
   connectivityFailureReason?: (input: { config: TConfig, error: unknown, errorMessage: string }) => string
   modelListFailureReason?: (input: { config: TConfig, error: unknown, errorMessage: string }) => string
+  chatCompletionTokenParameter?: 'max_tokens' | 'max_completion_tokens'
 }
 
 function extractStatusCode(error: unknown): number | null {
@@ -145,7 +146,9 @@ export function createOpenAICompatibleValidators<TConfig extends { apiKey?: stri
         // OpenRouter documents this minimum for some upstream providers.
         // Source/context: https://openrouter.ai/docs/api/api-reference/chat/send-chat-completion-request
         // Removal condition: All supported providers accept lower limits, or the probe learns each model's minimum.
-        max_tokens: 16,
+        ...(options?.chatCompletionTokenParameter === 'max_completion_tokens'
+          ? { max_completion_tokens: 16 }
+          : { max_tokens: 16 }),
       })
 
       return { connectivityOk: true, chatOk: true }