refactor(translation): 提取 ProviderStrategy 接口消除 AI 提供商分支

- 新建 app/lib/providers/ 策略模式（types + google + deepseek + index）
- 消除 AITranslation.ts 中 4 处 if (provider === ...) 分支
- 消除 ai-test.ts 中 2 处 if (provider === ...) 分支
- mapLevelToBudget/getThinkingConfig 迁移至 providers/ 策略实现内
- 用 generateText({ system }) 替代 messages 中的 system role 修复 AI SDK warning
- 新增 22 个单元测试覆盖各策略方法与工厂函数

Author: Chilfish

app/lib/AITranslation.ts

@@ -1,63 +1,16 @@
-import type { DeepSeekLanguageModelOptions } from '@ai-sdk/deepseek'
-import type { GoogleGenerativeAIProviderOptions } from '@ai-sdk/google'
 import type { LanguageModel, ModelMessage } from 'ai'
 import type { ThinkingLevel } from '~/lib/stores/appConfig'
 import type { EnrichedTweet, Entity } from '~/types'
-import { createDeepSeek } from '@ai-sdk/deepseek'
-import { createGoogleGenerativeAI } from '@ai-sdk/google'
 import { generateText, Output, zodSchema } from 'ai'
 import { z } from 'zod'
 import { models } from '~/lib/constants'
+import { getProviderStrategy, getThinkingConfig } from '~/lib/providers'
 import {
   applyAITranslations,
   restoreEntities,
   serializeForAI,
 } from '~/lib/react-tweet'
 
-/**
- * 将思考程度映射为 Gemini 2.0 的 thinkingBudget (token 数)
- */
-export function mapLevelToBudget(level: ThinkingLevel): number {
-  switch (level) {
-    case 'minimal': return 0
-    case 'low': return 1024
-    case 'medium': return 4096
-    case 'high': return 16384
-    case 'max': return 32768
-    default: return 0
-  }
-}
-
-/**
- * 获取对应模型的思考配置
- */
-export function getThinkingConfig(modelName: string, level: ThinkingLevel = 'minimal') {
-  const modelConfig = models.find(m => m.name === modelName)
-  const thinkingConfig: any = { includeThoughts: false }
-
-  if (!modelConfig)
-    return thinkingConfig
-
-  if (modelConfig.provider === 'google') {
-    if (modelConfig.thinkingType === 'level') {
-      thinkingConfig.thinkingLevel = level
-    }
-    else if (modelConfig.thinkingType === 'budget') {
-      thinkingConfig.thinkingBudget = mapLevelToBudget(level)
-    }
-  }
-  else if (modelConfig.provider === 'deepseek') {
-    // DeepSeek 映射逻辑
-    if (level === 'minimal')
-      return 'disabled'
-    if (level === 'max')
-      return 'max'
-    return 'high'
-  }
-
-  return thinkingConfig
-}
-
 /**
  * 将实体 Map 转换为 AI 可读的参考文本
  * 目的：让 AI 知道占位符背后是什么，以便更好地理解上下文，但不需要 AI 翻译它们
@@ -278,13 +231,11 @@ ${maskedText}
 `
 
   const baseMessages: ModelMessage[] = [
-    { role: 'system', content: systemPrompt },
     { role: 'user', content: userContent },
   ]
 
   const modelConfig = models.find(m => m.name === modelName)
-  const isDeepSeek = modelConfig?.provider === 'deepseek'
-  const isGoogle = modelConfig?.provider === 'google'
+  const strategy = modelConfig ? getProviderStrategy(modelConfig.provider) : null
 
   const thinkingConfig = getThinkingConfig(modelName, thinkingLevel)
   const expectedNewlineCount = countNewlines(maskedText)
@@ -308,22 +259,13 @@ ${maskedText}
     for (let attempt = 0; attempt < 2; attempt++) {
       const response = await generateText({
         model,
+        system: systemPrompt,
         messages,
         output,
         temperature: 0.5,
-        providerOptions: {
-          ...(isGoogle ? {
-            google: {
-              thinkingConfig,
-            } satisfies GoogleGenerativeAIProviderOptions,
-          } : {}),
-          ...(isDeepSeek && modelConfig?.thinkingType === 'level' ? {
-            deepseek: {
-              thinking: { type: thinkingConfig === 'disabled' ? 'disabled' : 'enabled' },
-              ...(thinkingConfig !== 'disabled' && typeof thinkingConfig === 'string' ? { reasoningEffort: thinkingConfig } : {}),
-            } satisfies DeepSeekLanguageModelOptions,
-          } : {}),
-        },
+        providerOptions: strategy && modelConfig
+          ? strategy.buildProviderOptions(thinkingConfig, modelConfig)
+          : {},
       })
 
       const translated = normalizeNewlineEscapes(response.output.translation, expectedNewlineCount).trim()
@@ -392,25 +334,16 @@ export async function autoTranslateTweet({
   }
   const entityContext = generateEntityContext(entityMap)
 
-  let aiProvider: any
-  if (provider === 'google') {
-    aiProvider = createGoogleGenerativeAI({
-      apiKey,
-    })
-  }
-  else {
-    aiProvider = createDeepSeek({
-      apiKey,
-    })
-  }
+  const strategy = getProviderStrategy(provider)
+  const sdkProvider = strategy.createSDKProvider(apiKey)
 
   const { translatedText, entityText } = await translateText({
     tweet,
     maskedText,
     entityContext,
     placeholders: Array.from(entityMap.keys()),
     entityMap,
-    model: aiProvider(model),
+    model: sdkProvider(model),
     modelName: model,
     translationGlossary,
     thinkingLevel,

app/lib/providers/deepseek.ts

@@ -0,0 +1,40 @@
+import type { DeepSeekLanguageModelOptions } from '@ai-sdk/deepseek'
+import type { ProviderStrategy } from './types'
+import type { ThinkingLevel } from '~/lib/stores/appConfig'
+import { createDeepSeek } from '@ai-sdk/deepseek'
+
+function resolveReasoningEffort(level: ThinkingLevel): string {
+  if (level === 'minimal')
+    return 'disabled'
+  if (level === 'max')
+    return 'max'
+  return 'high'
+}
+
+export const deepseekStrategy: ProviderStrategy = {
+  name: 'deepseek',
+
+  createSDKProvider(apiKey) {
+    return createDeepSeek({ apiKey })
+  },
+
+  getThinkingConfig(_modelConfig, level) {
+    return resolveReasoningEffort(level)
+  },
+
+  buildProviderOptions(thinkingConfig, modelConfig) {
+    if (modelConfig.thinkingType !== 'level')
+      return {}
+
+    return {
+      deepseek: {
+        thinking: {
+          type: thinkingConfig === 'disabled' ? 'disabled' : 'enabled',
+        },
+        ...(thinkingConfig !== 'disabled' && typeof thinkingConfig === 'string'
+          ? { reasoningEffort: thinkingConfig }
+          : {}),
+      },
+    } satisfies Record<string, DeepSeekLanguageModelOptions>
+  },
+}

app/lib/providers/google.ts

@@ -0,0 +1,40 @@
+import type { GoogleGenerativeAIProviderOptions } from '@ai-sdk/google'
+import type { ProviderStrategy } from './types'
+import type { ThinkingLevel } from '~/lib/stores/appConfig'
+import { createGoogleGenerativeAI } from '@ai-sdk/google'
+
+function mapLevelToBudget(level: ThinkingLevel): number {
+  switch (level) {
+    case 'minimal': return 0
+    case 'low': return 1024
+    case 'medium': return 4096
+    case 'high': return 16384
+    case 'max': return 32768
+    default: return 0
+  }
+}
+
+export const googleStrategy: ProviderStrategy = {
+  name: 'google',
+
+  createSDKProvider(apiKey) {
+    return createGoogleGenerativeAI({ apiKey })
+  },
+
+  getThinkingConfig(modelConfig, level) {
+    const config: any = { includeThoughts: false }
+    if (modelConfig.thinkingType === 'level') {
+      config.thinkingLevel = level
+    }
+    else if (modelConfig.thinkingType === 'budget') {
+      config.thinkingBudget = mapLevelToBudget(level)
+    }
+    return config
+  },
+
+  buildProviderOptions(thinkingConfig, _modelConfig) {
+    return {
+      google: { thinkingConfig },
+    } satisfies Record<string, GoogleGenerativeAIProviderOptions>
+  },
+}

app/lib/providers/index.ts

@@ -0,0 +1,38 @@
+import type { ProviderStrategy } from './types'
+import type { ThinkingLevel } from '~/lib/stores/appConfig'
+import { models } from '~/lib/constants'
+import { deepseekStrategy } from './deepseek'
+import { googleStrategy } from './google'
+
+const strategies: Record<string, ProviderStrategy> = {
+  google: googleStrategy,
+  deepseek: deepseekStrategy,
+}
+
+/**
+ * Get the ProviderStrategy for a given provider name.
+ * Throws if the provider is unknown.
+ */
+export function getProviderStrategy(provider: string): ProviderStrategy {
+  const strategy = strategies[provider]
+  if (!strategy) {
+    throw new Error(`Unknown AI provider: ${provider}. Supported: ${Object.keys(strategies).join(', ')}`)
+  }
+  return strategy
+}
+
+/**
+ * Convenience: resolve model name → model config → strategy → thinking config.
+ * Returns `{ includeThoughts: false }` as fallback for unknown models.
+ */
+export function getThinkingConfig(modelName: string, level: ThinkingLevel = 'minimal') {
+  const modelConfig = models.find(m => m.name === modelName)
+  if (!modelConfig) {
+    return { includeThoughts: false }
+  }
+  const strategy = getProviderStrategy(modelConfig.provider)
+  return strategy.getThinkingConfig(modelConfig, level)
+}
+
+export { deepseekStrategy, googleStrategy }
+export type { ProviderStrategy }

app/lib/providers/types.ts

@@ -0,0 +1,24 @@
+import type { ModelConfig } from '~/lib/constants'
+import type { ThinkingLevel } from '~/lib/stores/appConfig'
+
+export interface ProviderStrategy {
+  readonly name: string
+
+  /**
+   * Create an AI SDK provider instance from an API key.
+   * Returns a callable that accepts a model name and returns a LanguageModel.
+   */
+  createSDKProvider: (apiKey: string) => any
+
+  /**
+   * Build thinking configuration for generateText.
+   * Maps a user-selected ThinkingLevel to provider-specific config.
+   */
+  getThinkingConfig: (modelConfig: ModelConfig, level: ThinkingLevel) => any
+
+  /**
+   * Build the providerOptions object for generateText.
+   * Wraps thinking config into the provider-specific options structure.
+   */
+  buildProviderOptions: (thinkingConfig: any, modelConfig: ModelConfig) => Record<string, any>
+}

app/routes/api/ai/ai-test.ts

@@ -1,14 +1,10 @@
-import type { DeepSeekLanguageModelOptions } from '@ai-sdk/deepseek'
-import type { GoogleGenerativeAIProviderOptions } from '@ai-sdk/google'
 import type { ModelMessage } from 'ai'
 import type { Route } from './+types/ai-test'
-import { createDeepSeek } from '@ai-sdk/deepseek'
-import { createGoogleGenerativeAI } from '@ai-sdk/google'
 import { generateText } from 'ai'
 import { data } from 'react-router'
 import z from 'zod'
-import { getThinkingConfig } from '~/lib/AITranslation'
 import { models } from '~/lib/constants'
+import { getProviderStrategy, getThinkingConfig } from '~/lib/providers'
 import { getTweetSchema } from '~/lib/validations/tweet'
 
 export async function action({ request }: Route.ActionArgs) {
@@ -44,17 +40,8 @@ export async function action({ request }: Route.ActionArgs) {
   const provider = modelConfig?.provider || 'google'
 
   try {
-    let aiProvider: any
-    if (provider === 'google') {
-      aiProvider = createGoogleGenerativeAI({
-        apiKey,
-      })
-    }
-    else {
-      aiProvider = createDeepSeek({
-        apiKey,
-      })
-    }
+    const strategy = getProviderStrategy(provider)
+    const aiProvider = strategy.createSDKProvider(apiKey)
 
     const messages: ModelMessage[] = [
       { role: 'user', content: 'hello' },
@@ -66,18 +53,9 @@ export async function action({ request }: Route.ActionArgs) {
       model: aiProvider(model),
       messages,
       temperature: 1,
-      providerOptions: {
-        ...(provider === 'google' ? {
-          google: {
-            thinkingConfig,
-          } satisfies GoogleGenerativeAIProviderOptions,
-        } : {}),
-        ...(provider === 'deepseek' && model === 'deepseek-reasoner' ? {
-          deepseek: {
-            thinking: { type: 'enabled' },
-          } satisfies DeepSeekLanguageModelOptions,
-        } : {}),
-      },
+      providerOptions: modelConfig
+        ? strategy.buildProviderOptions(thinkingConfig, modelConfig)
+        : {},
     })
 
     const text = response.text.trim()