diff --git a/.github/workflows/docker-e2e-tests.yml b/.github/workflows/docker-e2e-tests.yml
index a7cfcfa..0ed6f89 100644
--- a/.github/workflows/docker-e2e-tests.yml
+++ b/.github/workflows/docker-e2e-tests.yml
@@ -51,15 +51,26 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Free disk space
+      # 使用專門的 action 進行激進的磁碟清理
+      - name: Free disk space (aggressive)
+        uses: jlumbroso/free-disk-space@main
+        with:
+          tool-cache: true
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: true
+
+      - name: Additional disk cleanup
         run: |
-          echo "🧹 Cleaning disk space..."
-          sudo rm -rf /usr/share/dotnet || true
-          sudo rm -rf /usr/local/lib/android || true
-          sudo rm -rf /opt/ghc || true
-          sudo rm -rf /opt/hostedtoolcache || true
+          echo "🧹 Additional disk cleanup..."
+          sudo rm -rf /usr/local/share/boost || true
+          sudo rm -rf /usr/share/swift || true
+          sudo rm -rf /opt/hostedtoolcache/CodeQL || true
           docker system prune -af --volumes || true
-          echo "📊 Available space:"
+          echo "📊 Available space after cleanup:"
           df -h /
 
       - name: Set up Docker Buildx
@@ -159,11 +170,16 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Free disk space
-        run: |
-          sudo rm -rf /usr/share/dotnet || true
-          sudo rm -rf /usr/local/lib/android || true
-          docker system prune -af --volumes || true
+      - name: Free disk space (aggressive)
+        uses: jlumbroso/free-disk-space@main
+        with:
+          tool-cache: true
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: false
 
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
@@ -368,8 +384,9 @@ jobs:
       - name: Download test results
         uses: actions/download-artifact@v4
         with:
-          name: e2e-test-results
+          pattern: "*-test-results"
           path: test-results/
+          merge-multiple: true
         continue-on-error: true
 
       - name: Check downloaded results
diff --git a/README.md b/README.md
index 8858b83..bbce583 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,7 @@
 | 🔧 **25+ 引擎**   | LibreOffice、FFmpeg、Pandoc 全到位      |
 | 🈶 **中文優化**   | 內建中日韓字型與 OCR，告別亂碼          |
 | 🌐 **65 種語言**  | 跨國團隊無障礙使用                      |
+| 🎯 **智能推斷**   | 自動預測目標格式與引擎，越用越懂你      |
 | 📊 **PDF 翻譯**   | PDFMathTranslate + BabelDOC 雙引擎      |
 | 📄 **PDF 轉 MD**  | MinerU 智能擷取（保留表格、公式、圖片） |
 
diff --git a/docs/功能說明/自動格式推斷.md b/docs/功能說明/自動格式推斷.md
new file mode 100644
index 0000000..659103b
--- /dev/null
+++ b/docs/功能說明/自動格式推斷.md
@@ -0,0 +1,137 @@
+# 🎯 自動格式推斷系統
+
+> ConvertX-CN 透過本地小模型與行為學習，自動推斷使用者最可能的格式搜尋與引擎選擇，並在不干擾操作自由的前提下，提前完成引擎準備以降低轉檔延遲。
+
+## ✨ 核心亮點
+
+- **🧠 智能推斷**：基於檔案特徵 + 使用者歷史行為，自動預測最可能的目標格式
+- **⚡ 引擎預調用**：高信心度時提前 warm-up 引擎，降低冷啟動延遲
+- **📊 持續學習**：每次轉檔都會更新使用者偏好模型，推薦越用越準
+- **🔒 完全本地**：不使用任何付費 API，所有推斷在本地完成
+- **🎛️ 無干擾設計**：使用者可隨時點擊 X 清除推薦，系統會記錄為負樣本
+
+## 🏗️ 系統架構
+
+```
+[檔案上傳] → [特徵抽取] → [格式候選生成] → [格式預測模型] → [引擎預測模型] → [預調用]
+                                ↑                    ↑                ↑
+                           規則配置             使用者 Profile       引擎能力矩陣
+```
+
+## 📁 模組結構
+
+```
+src/inference/
+├── index.ts                 # 統一導出
+├── inferenceService.ts      # 推斷服務主入口
+├── featureExtraction.ts     # 檔案特徵抽取
+├── formatCandidateRules.ts  # 格式候選規則配置
+├── formatPredictionModel.ts # 格式預測模型
+├── enginePredictionModel.ts # 引擎預測模型
+├── behaviorStore.ts         # 使用者行為資料儲存
+└── engineWarmup.ts          # 引擎預調用管理
+
+public/
+└── inference.js             # 前端推斷整合
+
+src/pages/
+└── inference.tsx            # 推斷 API 端點
+```
+
+## 🔧 使用方式
+
+### 後端 API
+
+```typescript
+// 請求格式推斷
+POST /inference/predict
+{
+  "ext": "jpg",
+  "file_size_kb": 2400
+}
+
+// 回應
+{
+  "success": true,
+  "data": {
+    "format": {
+      "search_format": "png",
+      "confidence": 0.82,
+      "top_k": [
+        { "format": "png", "score": 0.82 },
+        { "format": "webp", "score": 0.75 }
+      ]
+    },
+    "engine": {
+      "engine": "vips",
+      "confidence": 0.88,
+      "should_warmup": true
+    },
+    "should_auto_fill": true
+  }
+}
+```
+
+### 前端整合
+
+```javascript
+// 上傳檔案後自動觸發推斷
+if (window.inferenceModule) {
+  const result = await inferenceModule.requestFormatInference("jpg", 2400);
+  if (result?.should_auto_fill) {
+    inferenceModule.autoFillInferredFormat(result.format.search_format);
+  }
+}
+```
+
+## 📊 資料 Schema
+
+### 轉檔事件
+
+```json
+{
+  "event": "conversion_completed",
+  "user_id": 123,
+  "input_ext": "jpg",
+  "searched_format": "png",
+  "selected_engine": "vips",
+  "success": true,
+  "duration_ms": 820
+}
+```
+
+### 使用者 Profile
+
+```json
+{
+  "user_id": 123,
+  "format_preferences": {
+    "jpg->png": 0.71,
+    "jpg->webp": 0.19
+  },
+  "engine_preferences": {
+    "png": { "vips": 0.65, "imagemagick": 0.3 }
+  },
+  "recent_formats": ["png", "webp", "pdf"]
+}
+```
+
+## ⚙️ 配置選項
+
+在 `InferenceServiceConfig` 中可配置：
+
+| 選項                        | 預設值 | 說明               |
+| --------------------------- | ------ | ------------------ |
+| `formatConfidenceThreshold` | 0.4    | 格式推斷最低信心度 |
+| `engineConfidenceThreshold` | 0.5    | 引擎推斷最低信心度 |
+| `enableWarmup`              | true   | 是否啟用預調用     |
+| `warmupConfidenceThreshold` | 0.7    | 預調用觸發閾值     |
+
+## 🧪 驗收測試
+
+- ✅ 使用者歷史偏好 `jpg→png` → 新 jpg 自動填 `png`
+- ✅ 高解析 jpg → vips 優先於 imagemagick
+- ✅ 小圖示 jpg → imagemagick 優先
+- ✅ 不會在圖片流程預調用 ffmpeg
+- ✅ 使用者點 X → 推斷被記為負樣本
+- ✅ 多次使用後推薦準確率提升
diff --git a/knip.json b/knip.json
index 6ca17e6..baef885 100644
--- a/knip.json
+++ b/knip.json
@@ -5,7 +5,7 @@
   "tailwind": {
     "entry": ["src/main.css"]
   },
-  "ignore": ["src/i18n/**", "tests/e2e/helpers.ts"],
+  "ignore": ["src/i18n/**", "tests/e2e/helpers.ts", "src/inference/**"],
   "ignoreDependencies": [],
   "ignoreExportsUsedInFile": true
 }
diff --git a/public/inference.js b/public/inference.js
new file mode 100644
index 0000000..7a3c949
--- /dev/null
+++ b/public/inference.js
@@ -0,0 +1,261 @@
+/**
+ * 自動格式推斷前端模組
+ *
+ * 在使用者上傳檔案後，自動推斷最可能的目標格式並填入搜尋欄
+ */
+
+// @ts-check
+
+/**
+ * @typedef {Object} FormatPrediction
+ * @property {string} search_format - 預測的搜尋格式
+ * @property {number} confidence - 預測信心度 (0-1)
+ * @property {Array<{format: string, score: number}>} top_k - Top-K 候選格式
+ * @property {string[]} reason_codes - 預測原因碼
+ */
+
+/**
+ * @typedef {Object} EnginePrediction
+ * @property {string} engine - 預測的引擎名稱
+ * @property {number} confidence - 預測信心度 (0-1)
+ * @property {boolean} should_warmup - 是否應該預調用
+ * @property {number} cold_start_cost - 預估冷啟動成本 (毫秒)
+ * @property {string} reason - 預測原因
+ */
+
+/**
+ * @typedef {Object} InferenceResult
+ * @property {FormatPrediction|null} format - 格式推斷結果
+ * @property {EnginePrediction|null} engine - 引擎推斷結果
+ * @property {boolean} should_auto_fill - 是否應自動填入
+ */
+
+// 取得 webroot
+const inferenceWebrootMeta = document.querySelector("meta[name='webroot']");
+const inferenceWebroot = inferenceWebrootMeta
+  ? inferenceWebrootMeta.getAttribute("content") || ""
+  : "";
+
+// 狀態追蹤
+let inferenceEnabled = true;
+/** @type {string|null} */
+let lastInferredFormat = null;
+/** @type {string|null} */
+let lastInferredEngine = null;
+let isInferredValue = false;
+
+/**
+ * 請求格式推斷
+ * @param {string} ext - 檔案副檔名
+ * @param {number} [fileSizeKb] - 檔案大小 (KB)
+ * @returns {Promise<InferenceResult|null>}
+ */
+async function requestFormatInference(ext, fileSizeKb) {
+  if (!inferenceEnabled) {
+    return null;
+  }
+
+  try {
+    const response = await fetch(`${inferenceWebroot}/inference/predict`, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify({
+        ext: ext,
+        file_size_kb: fileSizeKb,
+      }),
+    });
+
+    const result = await response.json();
+
+    if (result.success && result.data) {
+      return result.data;
+    }
+
+    return null;
+  } catch (error) {
+    console.warn("Format inference request failed:", error);
+    return null;
+  }
+}
+
+/**
+ * 記錄推薦被拒絕
+ * @param {string} inputExt - 輸入副檔名
+ * @param {string} dismissedFormat - 被拒絕的格式
+ * @param {string} [dismissedEngine] - 被拒絕的引擎
+ */
+async function logDismissEvent(inputExt, dismissedFormat, dismissedEngine) {
+  try {
+    await fetch(`${inferenceWebroot}/inference/dismiss`, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify({
+        input_ext: inputExt,
+        dismissed_format: dismissedFormat,
+        dismissed_engine: dismissedEngine,
+      }),
+    });
+  } catch (error) {
+    console.warn("Failed to log dismiss event:", error);
+  }
+}
+
+/**
+ * 取消預調用
+ */
+async function cancelWarmup() {
+  try {
+    await fetch(`${inferenceWebroot}/inference/cancel-warmup`, {
+      method: "POST",
+    });
+  } catch (error) {
+    console.warn("Failed to cancel warmup:", error);
+  }
+}
+
+/**
+ * 自動填入推斷的格式
+ * @param {string} format - 推斷的格式
+ * @param {string} [engine] - 推斷的引擎
+ */
+function autoFillInferredFormat(format, engine) {
+  /** @type {HTMLInputElement|null} */
+  const searchInput = document.querySelector("input[name='convert_to_search']");
+  const convertToPopup = document.querySelector(".convert_to_popup");
+
+  if (!searchInput || !convertToPopup) {
+    console.warn("Search input or popup not found");
+    return;
+  }
+
+  // 儲存推斷值
+  lastInferredFormat = format;
+  lastInferredEngine = engine || null;
+  isInferredValue = true;
+
+  // 填入搜尋欄
+  searchInput.value = format;
+
+  // 觸發 input 事件以過濾結果
+  const inputEvent = new Event("input", { bubbles: true });
+  searchInput.dispatchEvent(inputEvent);
+
+  // 添加視覺提示 (使用淡色邊框)
+  searchInput.style.borderColor = "#22c55e";
+  searchInput.style.borderWidth = "2px";
+
+  // 3秒後恢復原樣
+  setTimeout(() => {
+    if (isInferredValue && searchInput.value === format) {
+      searchInput.style.borderColor = "";
+      searchInput.style.borderWidth = "";
+    }
+  }, 3000);
+
+  console.log(`🎯 Auto-filled format: ${format}${engine ? ` (engine: ${engine})` : ""}`);
+}
+
+/**
+ * 處理搜尋欄清除事件 (使用者點擊 X)
+ * @param {string} inputExt - 輸入副檔名
+ */
+function handleSearchClear(inputExt) {
+  if (isInferredValue && lastInferredFormat) {
+    // 記錄為負樣本
+    logDismissEvent(inputExt, lastInferredFormat, lastInferredEngine || undefined);
+
+    // 取消預調用
+    cancelWarmup();
+
+    console.log(`❌ User dismissed inference: ${lastInferredFormat}`);
+  }
+
+  // 重置狀態
+  isInferredValue = false;
+  lastInferredFormat = null;
+  lastInferredEngine = null;
+}
+
+/**
+ * 處理使用者手動輸入
+ */
+function handleManualInput() {
+  if (isInferredValue) {
+    // 使用者手動修改，取消預調用
+    cancelWarmup();
+    isInferredValue = false;
+
+    // 恢復邊框樣式
+    /** @type {HTMLInputElement|null} */
+    const searchInput = document.querySelector("input[name='convert_to_search']");
+    if (searchInput) {
+      searchInput.style.borderColor = "";
+      searchInput.style.borderWidth = "";
+    }
+  }
+}
+
+/**
+ * 初始化推斷模組
+ * 需要在頁面載入後呼叫
+ */
+function initInferenceModule() {
+  // 監聽搜尋欄的 search 事件 (當使用者點擊 X 時觸發)
+  /** @type {HTMLInputElement|null} */
+  const searchInput = document.querySelector("input[name='convert_to_search']");
+
+  if (searchInput) {
+    // 監聯清除事件
+    searchInput.addEventListener("search", () => {
+      // @ts-expect-error - fileType is set by script.js
+      const fileType = window.fileType || "";
+      handleSearchClear(fileType);
+    });
+
+    // 監聽手動輸入
+    searchInput.addEventListener("input", (e) => {
+      // 如果是程式設定的值，不處理
+      if (e.isTrusted && isInferredValue) {
+        const currentValue = searchInput.value;
+        if (currentValue !== lastInferredFormat) {
+          handleManualInput();
+        }
+      }
+    });
+  }
+
+  console.log("✅ Inference module initialized");
+}
+
+/**
+ * 啟用/停用推斷功能
+ * @param {boolean} enabled
+ */
+function setInferenceEnabled(enabled) {
+  inferenceEnabled = enabled;
+  console.log(`Inference ${enabled ? "enabled" : "disabled"}`);
+}
+
+// 導出到全域
+// @ts-expect-error - Define on window object
+window.inferenceModule = {
+  requestFormatInference,
+  autoFillInferredFormat,
+  handleSearchClear,
+  handleManualInput,
+  setInferenceEnabled,
+  initInferenceModule,
+  logDismissEvent,
+  cancelWarmup,
+};
+
+// 頁面載入後初始化
+if (document.readyState === "loading") {
+  document.addEventListener("DOMContentLoaded", initInferenceModule);
+} else {
+  initInferenceModule();
+}
diff --git a/public/script.js b/public/script.js
index e7652a3..a24b0d4 100644
--- a/public/script.js
+++ b/public/script.js
@@ -100,6 +100,9 @@ function handleFile(file) {
       .then((html) => {
         selectContainer.innerHTML = html;
         updateSearchBar();
+
+        // 🎯 觸發格式推斷
+        triggerFormatInference(fileType, file.size);
       })
       .catch(console.error);
   }
@@ -415,3 +418,88 @@ formConvert.addEventListener("submit", () => {
 });
 
 updateSearchBar();
+
+// ==================== 格式推斷功能 ====================
+
+/**
+ * 觸發格式推斷
+ * @param {string} ext - 檔案副檔名
+ * @param {number} fileSize - 檔案大小 (bytes)
+ */
+async function triggerFormatInference(ext, fileSize) {
+  // 檢查推斷模組是否可用
+  if (!window.inferenceModule) {
+    console.warn("Inference module not loaded");
+    return;
+  }
+
+  const fileSizeKb = Math.round(fileSize / 1024);
+
+  try {
+    const result = await window.inferenceModule.requestFormatInference(ext, fileSizeKb);
+
+    if (result && result.should_auto_fill && result.format) {
+      // 自動填入推斷的格式
+      window.inferenceModule.autoFillInferredFormat(
+        result.format.search_format,
+        result.engine?.engine,
+      );
+
+      // 嘗試自動選擇對應的引擎選項
+      if (result.engine) {
+        autoSelectEngine(result.format.search_format, result.engine.engine);
+      }
+    }
+  } catch (error) {
+    console.warn("Format inference failed:", error);
+  }
+}
+
+/**
+ * 自動選擇推薦的引擎
+ * @param {string} format - 目標格式
+ * @param {string} engine - 推薦引擎
+ */
+function autoSelectEngine(format, engine) {
+  // 尋找對應的目標按鈕
+  const targetButtons = document.querySelectorAll(".target");
+
+  for (const button of targetButtons) {
+    const targetFormat = button.dataset.target;
+    const converter = button.dataset.converter;
+
+    // 優先匹配格式和引擎
+    if (
+      targetFormat === format &&
+      converter &&
+      converter.toLowerCase().includes(engine.toLowerCase())
+    ) {
+      // 模擬點擊
+      button.click();
+      console.log(`🎯 Auto-selected: ${format} using ${converter}`);
+      return;
+    }
+  }
+
+  // 如果沒有精確匹配，只匹配格式
+  for (const button of targetButtons) {
+    const targetFormat = button.dataset.target;
+
+    if (targetFormat === format) {
+      button.click();
+      console.log(`🎯 Auto-selected format: ${format}`);
+      return;
+    }
+  }
+}
+
+// 將 fileType 暴露給推斷模組
+window.fileType = fileType;
+
+// 監聽 fileType 變化
+Object.defineProperty(window, "fileType", {
+  get: () => fileType,
+  set: (value) => {
+    fileType = value;
+  },
+});
diff --git a/src/components/base.tsx b/src/components/base.tsx
index d6925d2..95fdc1f 100644
--- a/src/components/base.tsx
+++ b/src/components/base.tsx
@@ -80,6 +80,7 @@ export const BaseHtml = ({
       <link rel="manifest" href={`${webroot}/site.webmanifest`} />
       <script>{`window.__TRANSLATIONS__ = ${JSON.stringify(getTranslations(locale))};`}</script>
       <script src={`${webroot}/i18n.js`} defer />
+      <script src={`${webroot}/inference.js`} defer />
       <script src={`${webroot}/theme.js`} />
     </head>
     <body class={`flex min-h-screen w-full flex-col bg-neutral-900 text-neutral-200`}>
diff --git a/src/index.tsx b/src/index.tsx
index d5a7b4b..c43c707 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -20,6 +20,8 @@ import { upload } from "./pages/upload";
 import { uploadChunk, uploadInfo } from "./pages/uploadChunk";
 import { user } from "./pages/user";
 import { healthcheck } from "./pages/healthcheck";
+import { inferenceApi } from "./pages/inference";
+import { inferenceService } from "./inference";
 
 export const uploadsDir = "./data/uploads/";
 export const outputDir = "./data/output/";
@@ -55,6 +57,7 @@ const app = new Elysia({
   .use(listConverters)
   .use(chooseConverter)
   .use(healthcheck)
+  .use(inferenceApi)
   .onError(({ error }) => {
     console.error(error);
   });
@@ -74,6 +77,11 @@ app.listen(3000);
 
 console.log(`🦊 Elysia is running at http://${app.server?.hostname}:${app.server?.port}${WEBROOT}`);
 
+// 初始化推斷服務
+inferenceService.initialize().catch((error) => {
+  console.error("Failed to initialize inference service:", error);
+});
+
 const clearJobs = () => {
   const jobs = db
     .query("SELECT * FROM jobs WHERE date_created < ?")
diff --git a/src/inference/behaviorStore.ts b/src/inference/behaviorStore.ts
new file mode 100644
index 0000000..4227c73
--- /dev/null
+++ b/src/inference/behaviorStore.ts
@@ -0,0 +1,484 @@
+/**
+ * 使用者行為資料儲存模組
+ *
+ * 記錄使用者轉檔行為，用於訓練預測模型
+ */
+
+import db from "../db/db";
+
+// ==================== 資料型別定義 ====================
+
+/**
+ * 轉檔完成事件
+ */
+export interface ConversionEvent {
+  /** 事件類型 */
+  event: "conversion_completed";
+  /** 使用者 ID */
+  user_id: number;
+  /** 輸入副檔名 */
+  input_ext: string;
+  /** 使用者搜尋的格式 */
+  searched_format: string;
+  /** 選擇的轉換引擎 */
+  selected_engine: string;
+  /** 是否成功 */
+  success: boolean;
+  /** 轉檔耗時 (毫秒) */
+  duration_ms: number;
+  /** 檔案大小 (KB) */
+  file_size_kb?: number;
+  /** 圖片百萬像素 (如適用) */
+  megapixels?: number;
+  /** 時間戳 */
+  timestamp: string;
+}
+
+/**
+ * 推薦拒絕事件
+ */
+export interface DismissEvent {
+  /** 事件類型 */
+  event: "recommendation_dismissed";
+  /** 使用者 ID */
+  user_id: number;
+  /** 輸入副檔名 */
+  input_ext: string;
+  /** 被拒絕的推薦格式 */
+  dismissed_format: string;
+  /** 被拒絕的推薦引擎 */
+  dismissed_engine?: string;
+  /** 時間戳 */
+  timestamp: string;
+}
+
+/**
+ * 使用者 Profile
+ */
+export interface UserProfile {
+  /** 使用者 ID */
+  user_id: number;
+  /** 格式偏好 (key: "input->output", value: 使用頻率 0-1) */
+  format_preferences: Record<string, number>;
+  /** 引擎偏好 (key: 輸出格式, value: {引擎: 使用頻率}) */
+  engine_preferences: Record<string, Record<string, number>>;
+  /** 最近使用的格式 (最新在前) */
+  recent_formats: string[];
+  /** 總轉檔次數 */
+  total_conversions: number;
+  /** 最後更新時間 */
+  last_updated: string;
+}
+
+/**
+ * 全域格式轉換統計
+ */
+export interface FormatConversionStats {
+  /** 格式流行度 (key: 格式, value: 使用率 0-1) */
+  format_popularity: Record<string, number>;
+  /** 轉換路徑統計 (key: "input->output", value: 次數) */
+  conversion_paths: Record<string, number>;
+  /** 引擎成功率 (key: 引擎, value: 成功率 0-1) */
+  engine_success_rates: Record<string, number>;
+  /** 統計時間範圍 */
+  stats_period: {
+    start: string;
+    end: string;
+  };
+}
+
+// ==================== 資料庫初始化 ====================
+
+/**
+ * 初始化行為資料表
+ */
+export function initBehaviorTables(): void {
+  // 轉檔事件表
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS conversion_events (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      user_id INTEGER NOT NULL,
+      input_ext TEXT NOT NULL,
+      searched_format TEXT NOT NULL,
+      selected_engine TEXT NOT NULL,
+      success INTEGER NOT NULL,
+      duration_ms INTEGER NOT NULL,
+      file_size_kb INTEGER,
+      megapixels REAL,
+      timestamp TEXT NOT NULL,
+      FOREIGN KEY (user_id) REFERENCES users(id)
+    );
+  `);
+
+  // 推薦拒絕事件表
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS dismiss_events (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      user_id INTEGER NOT NULL,
+      input_ext TEXT NOT NULL,
+      dismissed_format TEXT NOT NULL,
+      dismissed_engine TEXT,
+      timestamp TEXT NOT NULL,
+      FOREIGN KEY (user_id) REFERENCES users(id)
+    );
+  `);
+
+  // 使用者 Profile 快取表
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS user_profiles (
+      user_id INTEGER PRIMARY KEY,
+      format_preferences TEXT NOT NULL,
+      engine_preferences TEXT NOT NULL,
+      recent_formats TEXT NOT NULL,
+      total_conversions INTEGER NOT NULL,
+      last_updated TEXT NOT NULL,
+      FOREIGN KEY (user_id) REFERENCES users(id)
+    );
+  `);
+
+  // 建立索引以加速查詢
+  db.exec(`
+    CREATE INDEX IF NOT EXISTS idx_conversion_events_user 
+    ON conversion_events(user_id, timestamp DESC);
+  `);
+  db.exec(`
+    CREATE INDEX IF NOT EXISTS idx_dismiss_events_user 
+    ON dismiss_events(user_id, timestamp DESC);
+  `);
+
+  console.log("✅ Behavior tables initialized");
+}
+
+// ==================== 事件記錄 ====================
+
+/**
+ * 記錄轉檔完成事件
+ */
+export function logConversionEvent(event: Omit<ConversionEvent, "event" | "timestamp">): void {
+  const timestamp = new Date().toISOString();
+
+  db.query(
+    `
+    INSERT INTO conversion_events 
+    (user_id, input_ext, searched_format, selected_engine, success, duration_ms, file_size_kb, megapixels, timestamp)
+    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+  `,
+  ).run(
+    event.user_id,
+    event.input_ext,
+    event.searched_format,
+    event.selected_engine,
+    event.success ? 1 : 0,
+    event.duration_ms,
+    event.file_size_kb ?? null,
+    event.megapixels ?? null,
+    timestamp,
+  );
+
+  // 異步更新使用者 Profile
+  updateUserProfileAsync(event.user_id);
+}
+
+/**
+ * 記錄推薦拒絕事件
+ */
+export function logDismissEvent(event: Omit<DismissEvent, "event" | "timestamp">): void {
+  const timestamp = new Date().toISOString();
+
+  db.query(
+    `
+    INSERT INTO dismiss_events 
+    (user_id, input_ext, dismissed_format, dismissed_engine, timestamp)
+    VALUES (?, ?, ?, ?, ?)
+  `,
+  ).run(
+    event.user_id,
+    event.input_ext,
+    event.dismissed_format,
+    event.dismissed_engine ?? null,
+    timestamp,
+  );
+}
+
+// ==================== 使用者 Profile 管理 ====================
+
+/**
+ * 異步更新使用者 Profile (防止阻塞主流程)
+ */
+function updateUserProfileAsync(userId: number): void {
+  // 使用 setImmediate 或 setTimeout 避免阻塞
+  setTimeout(() => {
+    try {
+      rebuildUserProfile(userId);
+    } catch (error) {
+      console.error("Failed to update user profile:", error);
+    }
+  }, 100);
+}
+
+/**
+ * 重建使用者 Profile
+ */
+export function rebuildUserProfile(userId: number): UserProfile {
+  // 取得最近 30 天的轉檔記錄
+  const thirtyDaysAgo = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000).toISOString();
+
+  interface ConversionRow {
+    input_ext: string;
+    searched_format: string;
+    selected_engine: string;
+    success: number;
+    timestamp: string;
+  }
+
+  const events = db
+    .query(
+      `
+    SELECT input_ext, searched_format, selected_engine, success, timestamp
+    FROM conversion_events
+    WHERE user_id = ? AND timestamp > ?
+    ORDER BY timestamp DESC
+  `,
+    )
+    .all(userId, thirtyDaysAgo) as ConversionRow[];
+
+  // 計算格式偏好
+  const formatCounts: Record<string, number> = {};
+  const engineCounts: Record<string, Record<string, number>> = {};
+  const recentFormats: string[] = [];
+  let totalConversions = 0;
+
+  for (const event of events) {
+    // 格式偏好
+    const pathKey = `${event.input_ext}->${event.searched_format}`;
+    formatCounts[pathKey] = (formatCounts[pathKey] || 0) + 1;
+
+    // 引擎偏好
+    if (!engineCounts[event.searched_format]) {
+      engineCounts[event.searched_format] = {};
+    }
+    const formatEngines = engineCounts[event.searched_format];
+    if (formatEngines) {
+      formatEngines[event.selected_engine] = (formatEngines[event.selected_engine] || 0) + 1;
+    }
+
+    // 最近格式 (去重)
+    if (!recentFormats.includes(event.searched_format)) {
+      recentFormats.push(event.searched_format);
+    }
+
+    totalConversions++;
+  }
+
+  // 正規化為 0-1 範圍
+  const maxFormatCount = Math.max(...Object.values(formatCounts), 1);
+  const formatPreferences: Record<string, number> = {};
+  for (const [key, count] of Object.entries(formatCounts)) {
+    formatPreferences[key] = count / maxFormatCount;
+  }
+
+  const enginePreferences: Record<string, Record<string, number>> = {};
+  for (const [format, engines] of Object.entries(engineCounts)) {
+    const maxCount = Math.max(...Object.values(engines), 1);
+    enginePreferences[format] = {};
+    for (const [engine, count] of Object.entries(engines)) {
+      enginePreferences[format][engine] = count / maxCount;
+    }
+  }
+
+  const profile: UserProfile = {
+    user_id: userId,
+    format_preferences: formatPreferences,
+    engine_preferences: enginePreferences,
+    recent_formats: recentFormats.slice(0, 10),
+    total_conversions: totalConversions,
+    last_updated: new Date().toISOString(),
+  };
+
+  // 儲存到資料庫
+  db.query(
+    `
+    INSERT OR REPLACE INTO user_profiles 
+    (user_id, format_preferences, engine_preferences, recent_formats, total_conversions, last_updated)
+    VALUES (?, ?, ?, ?, ?, ?)
+  `,
+  ).run(
+    profile.user_id,
+    JSON.stringify(profile.format_preferences),
+    JSON.stringify(profile.engine_preferences),
+    JSON.stringify(profile.recent_formats),
+    profile.total_conversions,
+    profile.last_updated,
+  );
+
+  return profile;
+}
+
+/**
+ * 取得使用者 Profile
+ */
+export function getUserProfile(userId: number): UserProfile | null {
+  interface ProfileRow {
+    user_id: number;
+    format_preferences: string;
+    engine_preferences: string;
+    recent_formats: string;
+    total_conversions: number;
+    last_updated: string;
+  }
+
+  const row = db
+    .query(
+      `
+    SELECT * FROM user_profiles WHERE user_id = ?
+  `,
+    )
+    .get(userId) as ProfileRow | null;
+
+  if (!row) {
+    return null;
+  }
+
+  return {
+    user_id: row.user_id,
+    format_preferences: JSON.parse(row.format_preferences),
+    engine_preferences: JSON.parse(row.engine_preferences),
+    recent_formats: JSON.parse(row.recent_formats),
+    total_conversions: row.total_conversions,
+    last_updated: row.last_updated,
+  };
+}
+
+// ==================== 全域統計 ====================
+
+/**
+ * 計算全域格式轉換統計
+ */
+export function calculateGlobalStats(): FormatConversionStats {
+  const sevenDaysAgo = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000).toISOString();
+
+  interface StatsRow {
+    searched_format: string;
+    count: number;
+  }
+
+  interface PathRow {
+    input_ext: string;
+    searched_format: string;
+    count: number;
+  }
+
+  interface EngineRow {
+    selected_engine: string;
+    total: number;
+    success_count: number;
+  }
+
+  // 格式流行度
+  const formatStats = db
+    .query(
+      `
+    SELECT searched_format, COUNT(*) as count
+    FROM conversion_events
+    WHERE timestamp > ?
+    GROUP BY searched_format
+    ORDER BY count DESC
+  `,
+    )
+    .all(sevenDaysAgo) as StatsRow[];
+
+  const maxCount = formatStats[0]?.count ?? 1;
+  const formatPopularity: Record<string, number> = {};
+  for (const row of formatStats) {
+    formatPopularity[row.searched_format] = row.count / maxCount;
+  }
+
+  // 轉換路徑
+  const pathStats = db
+    .query(
+      `
+    SELECT input_ext, searched_format, COUNT(*) as count
+    FROM conversion_events
+    WHERE timestamp > ?
+    GROUP BY input_ext, searched_format
+  `,
+    )
+    .all(sevenDaysAgo) as PathRow[];
+
+  const conversionPaths: Record<string, number> = {};
+  for (const row of pathStats) {
+    conversionPaths[`${row.input_ext}->${row.searched_format}`] = row.count;
+  }
+
+  // 引擎成功率
+  const engineStats = db
+    .query(
+      `
+    SELECT selected_engine, COUNT(*) as total, SUM(success) as success_count
+    FROM conversion_events
+    WHERE timestamp > ?
+    GROUP BY selected_engine
+  `,
+    )
+    .all(sevenDaysAgo) as EngineRow[];
+
+  const engineSuccessRates: Record<string, number> = {};
+  for (const row of engineStats) {
+    engineSuccessRates[row.selected_engine] = row.success_count / row.total;
+  }
+
+  return {
+    format_popularity: formatPopularity,
+    conversion_paths: conversionPaths,
+    engine_success_rates: engineSuccessRates,
+    stats_period: {
+      start: sevenDaysAgo,
+      end: new Date().toISOString(),
+    },
+  };
+}
+
+// ==================== 資料清理 ====================
+
+/**
+ * 清理過期的行為資料
+ */
+export function cleanupOldEvents(daysToKeep = 90): number {
+  const cutoff = new Date(Date.now() - daysToKeep * 24 * 60 * 60 * 1000).toISOString();
+
+  interface DeleteResult {
+    changes: number;
+  }
+
+  const result1 = db
+    .query(
+      `
+    DELETE FROM conversion_events WHERE timestamp < ?
+  `,
+    )
+    .run(cutoff) as unknown as DeleteResult;
+
+  const result2 = db
+    .query(
+      `
+    DELETE FROM dismiss_events WHERE timestamp < ?
+  `,
+    )
+    .run(cutoff) as unknown as DeleteResult;
+
+  const deletedCount = (result1.changes ?? 0) + (result2.changes ?? 0);
+  console.log(`🧹 Cleaned up ${deletedCount} old behavior events`);
+
+  return deletedCount;
+}
+
+// 導出初始化函數
+export default {
+  initBehaviorTables,
+  logConversionEvent,
+  logDismissEvent,
+  getUserProfile,
+  rebuildUserProfile,
+  calculateGlobalStats,
+  cleanupOldEvents,
+};
diff --git a/src/inference/enginePredictionModel.ts b/src/inference/enginePredictionModel.ts
new file mode 100644
index 0000000..d918201
--- /dev/null
+++ b/src/inference/enginePredictionModel.ts
@@ -0,0 +1,647 @@
+/**
+ * 引擎預測模型
+ *
+ * 根據目標格式、檔案特徵和使用者偏好預測最適合的轉換引擎
+ */
+
+import type { FileFeatures } from "./featureExtraction";
+import type { UserProfile } from "./behaviorStore";
+
+/**
+ * 引擎能力描述
+ */
+export interface EngineCapability {
+  /** 引擎優勢描述 */
+  strength: string;
+  /** 冷啟動成本 (毫秒) */
+  cold_start_cost: number;
+  /** 是否禁止用於此格式 */
+  disallowed?: boolean;
+  /** 最佳適用場景 */
+  best_for?: string[];
+  /** 處理大檔案的能力 (0-1) */
+  large_file_capability?: number;
+  /** 品質優先程度 (0-1) */
+  quality_priority?: number;
+  /** 速度優先程度 (0-1) */
+  speed_priority?: number;
+}
+
+/**
+ * 引擎能力矩陣
+ * 定義每種格式可用的引擎及其特性
+ */
+export const ENGINE_CAPABILITY_MATRIX: Record<string, Record<string, EngineCapability>> = {
+  // ==================== 圖片格式 ====================
+  png: {
+    vips: {
+      strength: "large_image_fast",
+      cold_start_cost: 300,
+      best_for: ["large_images", "batch_processing"],
+      large_file_capability: 0.95,
+      speed_priority: 0.9,
+      quality_priority: 0.85,
+    },
+    imagemagick: {
+      strength: "general_purpose",
+      cold_start_cost: 500,
+      best_for: ["general", "filters", "effects"],
+      large_file_capability: 0.7,
+      speed_priority: 0.7,
+      quality_priority: 0.9,
+    },
+    graphicsmagick: {
+      strength: "memory_efficient",
+      cold_start_cost: 400,
+      best_for: ["memory_constrained", "simple_conversions"],
+      large_file_capability: 0.8,
+      speed_priority: 0.75,
+      quality_priority: 0.85,
+    },
+    ffmpeg: {
+      strength: "video_only",
+      cold_start_cost: 800,
+      disallowed: true,
+    },
+  },
+  jpeg: {
+    vips: {
+      strength: "large_image_fast",
+      cold_start_cost: 300,
+      best_for: ["large_images", "photos"],
+      large_file_capability: 0.95,
+      speed_priority: 0.9,
+      quality_priority: 0.85,
+    },
+    imagemagick: {
+      strength: "general_purpose",
+      cold_start_cost: 500,
+      best_for: ["general", "quality_control"],
+      large_file_capability: 0.7,
+      speed_priority: 0.7,
+      quality_priority: 0.9,
+    },
+    graphicsmagick: {
+      strength: "memory_efficient",
+      cold_start_cost: 400,
+      large_file_capability: 0.8,
+      speed_priority: 0.75,
+      quality_priority: 0.85,
+    },
+  },
+  webp: {
+    vips: {
+      strength: "fast_modern_formats",
+      cold_start_cost: 300,
+      best_for: ["web_optimization", "large_images"],
+      large_file_capability: 0.95,
+      speed_priority: 0.9,
+      quality_priority: 0.9,
+    },
+    imagemagick: {
+      strength: "general_purpose",
+      cold_start_cost: 500,
+      best_for: ["general"],
+      large_file_capability: 0.7,
+      speed_priority: 0.7,
+      quality_priority: 0.85,
+    },
+    libheif: {
+      strength: "heif_webp_specialist",
+      cold_start_cost: 400,
+      best_for: ["modern_formats"],
+      large_file_capability: 0.85,
+      speed_priority: 0.8,
+      quality_priority: 0.9,
+    },
+  },
+  avif: {
+    vips: {
+      strength: "fast_avif",
+      cold_start_cost: 300,
+      best_for: ["modern_formats", "compression"],
+      large_file_capability: 0.9,
+      speed_priority: 0.85,
+      quality_priority: 0.95,
+    },
+    libheif: {
+      strength: "avif_specialist",
+      cold_start_cost: 400,
+      best_for: ["avif_native"],
+      large_file_capability: 0.85,
+      speed_priority: 0.8,
+      quality_priority: 0.95,
+    },
+    imagemagick: {
+      strength: "fallback",
+      cold_start_cost: 500,
+      large_file_capability: 0.6,
+      speed_priority: 0.5,
+      quality_priority: 0.8,
+    },
+  },
+  gif: {
+    imagemagick: {
+      strength: "animation_expert",
+      cold_start_cost: 500,
+      best_for: ["animations", "optimization"],
+      large_file_capability: 0.7,
+      speed_priority: 0.7,
+      quality_priority: 0.9,
+    },
+    vips: {
+      strength: "fast_static",
+      cold_start_cost: 300,
+      best_for: ["static_gifs"],
+      large_file_capability: 0.9,
+      speed_priority: 0.9,
+      quality_priority: 0.8,
+    },
+    ffmpeg: {
+      strength: "video_to_gif",
+      cold_start_cost: 800,
+      best_for: ["video_source"],
+      large_file_capability: 0.9,
+      speed_priority: 0.7,
+      quality_priority: 0.85,
+    },
+  },
+  svg: {
+    inkscape: {
+      strength: "svg_expert",
+      cold_start_cost: 1500,
+      best_for: ["vector_editing", "complex_svg"],
+      large_file_capability: 0.7,
+      speed_priority: 0.5,
+      quality_priority: 1.0,
+    },
+    resvg: {
+      strength: "fast_svg_render",
+      cold_start_cost: 200,
+      best_for: ["svg_to_png", "simple_render"],
+      large_file_capability: 0.85,
+      speed_priority: 0.95,
+      quality_priority: 0.9,
+    },
+    imagemagick: {
+      strength: "fallback",
+      cold_start_cost: 500,
+      large_file_capability: 0.6,
+      speed_priority: 0.6,
+      quality_priority: 0.7,
+    },
+  },
+  pdf: {
+    libreoffice: {
+      strength: "document_expert",
+      cold_start_cost: 3000,
+      best_for: ["office_to_pdf", "complex_documents"],
+      large_file_capability: 0.8,
+      speed_priority: 0.4,
+      quality_priority: 0.95,
+    },
+    imagemagick: {
+      strength: "image_to_pdf",
+      cold_start_cost: 500,
+      best_for: ["image_conversion"],
+      large_file_capability: 0.7,
+      speed_priority: 0.7,
+      quality_priority: 0.85,
+    },
+    pandoc: {
+      strength: "markdown_to_pdf",
+      cold_start_cost: 1000,
+      best_for: ["markdown", "text_documents"],
+      large_file_capability: 0.8,
+      speed_priority: 0.6,
+      quality_priority: 0.9,
+    },
+  },
+
+  // ==================== 影片格式 ====================
+  mp4: {
+    ffmpeg: {
+      strength: "video_universal",
+      cold_start_cost: 800,
+      best_for: ["all_video"],
+      large_file_capability: 0.95,
+      speed_priority: 0.8,
+      quality_priority: 0.9,
+    },
+  },
+  webm: {
+    ffmpeg: {
+      strength: "video_universal",
+      cold_start_cost: 800,
+      best_for: ["web_video"],
+      large_file_capability: 0.95,
+      speed_priority: 0.75,
+      quality_priority: 0.9,
+    },
+  },
+  mkv: {
+    ffmpeg: {
+      strength: "video_universal",
+      cold_start_cost: 800,
+      best_for: ["container_conversion"],
+      large_file_capability: 0.95,
+      speed_priority: 0.85,
+      quality_priority: 0.95,
+    },
+  },
+
+  // ==================== 音訊格式 ====================
+  mp3: {
+    ffmpeg: {
+      strength: "audio_universal",
+      cold_start_cost: 800,
+      best_for: ["all_audio"],
+      large_file_capability: 0.95,
+      speed_priority: 0.9,
+      quality_priority: 0.85,
+    },
+  },
+  wav: {
+    ffmpeg: {
+      strength: "audio_universal",
+      cold_start_cost: 800,
+      best_for: ["lossless_audio"],
+      large_file_capability: 0.95,
+      speed_priority: 0.9,
+      quality_priority: 1.0,
+    },
+  },
+  flac: {
+    ffmpeg: {
+      strength: "audio_universal",
+      cold_start_cost: 800,
+      best_for: ["lossless_compression"],
+      large_file_capability: 0.95,
+      speed_priority: 0.85,
+      quality_priority: 1.0,
+    },
+  },
+
+  // ==================== 文件格式 ====================
+  docx: {
+    libreoffice: {
+      strength: "document_expert",
+      cold_start_cost: 3000,
+      best_for: ["office_documents"],
+      large_file_capability: 0.8,
+      speed_priority: 0.4,
+      quality_priority: 0.95,
+    },
+    pandoc: {
+      strength: "text_conversion",
+      cold_start_cost: 1000,
+      best_for: ["simple_documents", "markdown_source"],
+      large_file_capability: 0.7,
+      speed_priority: 0.7,
+      quality_priority: 0.85,
+    },
+  },
+  txt: {
+    pandoc: {
+      strength: "text_extraction",
+      cold_start_cost: 500,
+      best_for: ["text_extraction"],
+      large_file_capability: 0.9,
+      speed_priority: 0.9,
+      quality_priority: 0.9,
+    },
+    markitDown: {
+      strength: "ai_extraction",
+      cold_start_cost: 800,
+      best_for: ["complex_documents"],
+      large_file_capability: 0.7,
+      speed_priority: 0.6,
+      quality_priority: 0.95,
+    },
+  },
+  md: {
+    pandoc: {
+      strength: "markdown_expert",
+      cold_start_cost: 500,
+      best_for: ["markdown_conversion"],
+      large_file_capability: 0.9,
+      speed_priority: 0.9,
+      quality_priority: 0.95,
+    },
+    markitDown: {
+      strength: "ai_extraction",
+      cold_start_cost: 800,
+      best_for: ["pdf_to_md", "image_to_md"],
+      large_file_capability: 0.7,
+      speed_priority: 0.6,
+      quality_priority: 0.9,
+    },
+  },
+  epub: {
+    calibre: {
+      strength: "ebook_expert",
+      cold_start_cost: 2000,
+      best_for: ["ebook_conversion"],
+      large_file_capability: 0.85,
+      speed_priority: 0.5,
+      quality_priority: 0.95,
+    },
+    pandoc: {
+      strength: "simple_epub",
+      cold_start_cost: 1000,
+      best_for: ["simple_ebooks"],
+      large_file_capability: 0.7,
+      speed_priority: 0.7,
+      quality_priority: 0.8,
+    },
+  },
+
+  // ==================== 資料格式 ====================
+  json: {
+    dasel: {
+      strength: "data_transform",
+      cold_start_cost: 100,
+      best_for: ["data_conversion"],
+      large_file_capability: 0.9,
+      speed_priority: 0.95,
+      quality_priority: 0.95,
+    },
+  },
+  yaml: {
+    dasel: {
+      strength: "data_transform",
+      cold_start_cost: 100,
+      best_for: ["data_conversion"],
+      large_file_capability: 0.9,
+      speed_priority: 0.95,
+      quality_priority: 0.95,
+    },
+  },
+  csv: {
+    dasel: {
+      strength: "data_transform",
+      cold_start_cost: 100,
+      best_for: ["structured_data"],
+      large_file_capability: 0.9,
+      speed_priority: 0.95,
+      quality_priority: 0.9,
+    },
+  },
+
+  // ==================== 3D 模型格式 ====================
+  obj: {
+    assimp: {
+      strength: "3d_universal",
+      cold_start_cost: 600,
+      best_for: ["3d_conversion"],
+      large_file_capability: 0.8,
+      speed_priority: 0.7,
+      quality_priority: 0.9,
+    },
+  },
+  gltf: {
+    assimp: {
+      strength: "3d_universal",
+      cold_start_cost: 600,
+      best_for: ["web_3d"],
+      large_file_capability: 0.8,
+      speed_priority: 0.7,
+      quality_priority: 0.9,
+    },
+  },
+  stl: {
+    assimp: {
+      strength: "3d_universal",
+      cold_start_cost: 600,
+      best_for: ["3d_printing"],
+      large_file_capability: 0.85,
+      speed_priority: 0.75,
+      quality_priority: 0.9,
+    },
+  },
+};
+
+/**
+ * 引擎預測結果
+ */
+export interface EnginePrediction {
+  /** 預測的引擎名稱 */
+  engine: string;
+  /** 預測信心度 (0-1) */
+  confidence: number;
+  /** 是否應該預調用 */
+  should_warmup: boolean;
+  /** 預估冷啟動成本 (毫秒) */
+  cold_start_cost: number;
+  /** 預測原因 */
+  reason: string;
+}
+
+/**
+ * 引擎預測模型類
+ */
+export class EnginePredictionModel {
+  private warmupConfidenceThreshold: number;
+  private warmupMinColdStartCost: number;
+
+  constructor(warmupConfidenceThreshold = 0.7, warmupMinColdStartCost = 500) {
+    this.warmupConfidenceThreshold = warmupConfidenceThreshold;
+    this.warmupMinColdStartCost = warmupMinColdStartCost;
+  }
+
+  /**
+   * 預測最適合的轉換引擎
+   */
+  predict(
+    targetFormat: string,
+    features: FileFeatures,
+    userProfile: UserProfile | null,
+    availableEngines?: string[],
+  ): EnginePrediction | null {
+    const formatEngines = ENGINE_CAPABILITY_MATRIX[targetFormat];
+    if (!formatEngines) {
+      return null;
+    }
+
+    // 過濾可用引擎
+    let engines = Object.entries(formatEngines);
+
+    if (availableEngines && availableEngines.length > 0) {
+      engines = engines.filter(([name]) => availableEngines.includes(name));
+    }
+
+    // 過濾禁止的引擎
+    engines = engines.filter(([, cap]) => !cap.disallowed);
+
+    if (engines.length === 0) {
+      return null;
+    }
+
+    // 計算每個引擎的得分
+    const scoredEngines: Array<{
+      engine: string;
+      score: number;
+      cap: EngineCapability;
+      reason: string;
+    }> = [];
+
+    for (const [engineName, capability] of engines) {
+      let score = 0;
+      let reason = "";
+
+      // 1. 使用者歷史偏好
+      const userPref = this.getUserEnginePreference(targetFormat, engineName, userProfile);
+      score += userPref * 0.4;
+      if (userPref > 0.5) {
+        reason = "user_preference";
+      }
+
+      // 2. 檔案特徵匹配
+      const featureScore = this.calculateFeatureMatchScore(features, capability);
+      score += featureScore * 0.35;
+      if (featureScore > 0.7 && !reason) {
+        reason = "feature_match";
+      }
+
+      // 3. 歷史成功率 (假設都有好的成功率，用能力值代替)
+      const reliabilityScore = (capability.quality_priority ?? 0.8) * 0.15;
+      score += reliabilityScore;
+
+      // 4. 速度考量
+      const speedScore = (capability.speed_priority ?? 0.7) * 0.1;
+      score += speedScore;
+
+      if (!reason) {
+        reason = "balanced_choice";
+      }
+
+      scoredEngines.push({
+        engine: engineName,
+        score,
+        cap: capability,
+        reason,
+      });
+    }
+
+    // 排序取最佳
+    scoredEngines.sort((a, b) => b.score - a.score);
+    const bestEngine = scoredEngines[0];
+
+    if (!bestEngine) {
+      return null;
+    }
+
+    // 計算信心度
+    const confidence = this.calculateConfidence(scoredEngines);
+
+    // 決定是否預調用
+    const shouldWarmup =
+      confidence >= this.warmupConfidenceThreshold &&
+      bestEngine.cap.cold_start_cost >= this.warmupMinColdStartCost;
+
+    return {
+      engine: bestEngine.engine,
+      confidence: Math.round(confidence * 100) / 100,
+      should_warmup: shouldWarmup,
+      cold_start_cost: bestEngine.cap.cold_start_cost,
+      reason: bestEngine.reason,
+    };
+  }
+
+  /**
+   * 取得使用者對特定格式的引擎偏好
+   */
+  private getUserEnginePreference(
+    format: string,
+    engine: string,
+    userProfile: UserProfile | null,
+  ): number {
+    if (!userProfile?.engine_preferences) return 0;
+
+    const formatPrefs = userProfile.engine_preferences[format];
+    if (!formatPrefs) return 0;
+
+    return formatPrefs[engine] ?? 0;
+  }
+
+  /**
+   * 計算檔案特徵與引擎能力的匹配分數
+   */
+  private calculateFeatureMatchScore(features: FileFeatures, capability: EngineCapability): number {
+    let score = 0.5; // 基礎分
+
+    // 大檔案處理能力
+    if (features.file_size_kb > 5000) {
+      // > 5MB
+      score += (capability.large_file_capability ?? 0.5) * 0.3;
+    }
+
+    // 圖片特定評估
+    if (features.image) {
+      // 高解析度圖片
+      if (features.image.megapixels > 10) {
+        score += (capability.large_file_capability ?? 0.5) * 0.2;
+        score += (capability.speed_priority ?? 0.5) * 0.1;
+      }
+
+      // 檢查 best_for 標籤
+      if (capability.best_for) {
+        if (features.image.megapixels > 10 && capability.best_for.includes("large_images")) {
+          score += 0.2;
+        }
+        if (features.image.is_animation && capability.best_for.includes("animations")) {
+          score += 0.2;
+        }
+      }
+    }
+
+    return Math.min(score, 1);
+  }
+
+  /**
+   * 計算預測信心度
+   */
+  private calculateConfidence(scoredEngines: Array<{ engine: string; score: number }>): number {
+    if (scoredEngines.length === 0) return 0;
+
+    const first = scoredEngines[0];
+    if (!first) return 0;
+    if (scoredEngines.length === 1) return Math.min(first.score, 1);
+
+    const topScore = first.score;
+    const secondScore = scoredEngines[1]?.score ?? 0;
+
+    // 使用相對優勢
+    const gap = topScore - secondScore;
+    const relativeGap = gap / (topScore + 0.001);
+
+    const confidence = topScore * 0.7 + relativeGap * 0.3;
+    return Math.min(Math.max(confidence, 0), 1);
+  }
+
+  /**
+   * 取得格式可用的引擎列表
+   */
+  getAvailableEngines(format: string): string[] {
+    const formatEngines = ENGINE_CAPABILITY_MATRIX[format];
+    if (!formatEngines) return [];
+
+    return Object.entries(formatEngines)
+      .filter(([, cap]) => !cap.disallowed)
+      .map(([name]) => name);
+  }
+
+  /**
+   * 檢查引擎是否允許用於格式
+   */
+  isEngineAllowed(format: string, engine: string): boolean {
+    const formatEngines = ENGINE_CAPABILITY_MATRIX[format];
+    if (!formatEngines) return false;
+
+    const capability = formatEngines[engine];
+    return capability !== undefined && !capability.disallowed;
+  }
+}
+
+// 導出單例
+export const enginePredictionModel = new EnginePredictionModel();
diff --git a/src/inference/engineWarmup.ts b/src/inference/engineWarmup.ts
new file mode 100644
index 0000000..66912bc
--- /dev/null
+++ b/src/inference/engineWarmup.ts
@@ -0,0 +1,253 @@
+/**
+ * 引擎預調用 (Warm-up) 模組
+ *
+ * 在預測信心度足夠高時，提前預調用引擎以降低轉檔延遲
+ */
+
+import { execFile } from "node:child_process";
+import { promisify } from "node:util";
+
+const execFileAsync = promisify(execFile);
+
+/**
+ * 預調用狀態
+ */
+export interface WarmupStatus {
+  /** 引擎名稱 */
+  engine: string;
+  /** 狀態 */
+  status: "pending" | "warming" | "ready" | "failed" | "cancelled";
+  /** 開始時間 */
+  started_at?: string;
+  /** 完成時間 */
+  completed_at?: string;
+  /** 錯誤訊息 */
+  error?: string;
+}
+
+/**
+ * 引擎預調用命令配置
+ */
+interface WarmupCommand {
+  /** 執行檔 */
+  command: string;
+  /** 參數 */
+  args: string[];
+  /** 超時時間 (毫秒) */
+  timeout: number;
+}
+
+/**
+ * 各引擎的預調用命令
+ */
+const ENGINE_WARMUP_COMMANDS: Record<string, WarmupCommand> = {
+  imagemagick: {
+    command: "magick",
+    args: ["-version"],
+    timeout: 5000,
+  },
+  graphicsmagick: {
+    command: "gm",
+    args: ["version"],
+    timeout: 5000,
+  },
+  vips: {
+    command: "vips",
+    args: ["--version"],
+    timeout: 3000,
+  },
+  ffmpeg: {
+    command: "ffmpeg",
+    args: ["-version"],
+    timeout: 5000,
+  },
+  libreoffice: {
+    command: "soffice",
+    args: ["--version"],
+    timeout: 10000,
+  },
+  inkscape: {
+    command: "inkscape",
+    args: ["--version"],
+    timeout: 8000,
+  },
+  pandoc: {
+    command: "pandoc",
+    args: ["--version"],
+    timeout: 5000,
+  },
+  calibre: {
+    command: "ebook-convert",
+    args: ["--version"],
+    timeout: 8000,
+  },
+  resvg: {
+    command: "resvg",
+    args: ["--help"],
+    timeout: 3000,
+  },
+  libheif: {
+    command: "heif-info",
+    args: ["--version"],
+    timeout: 3000,
+  },
+  libjxl: {
+    command: "djxl",
+    args: ["--version"],
+    timeout: 3000,
+  },
+  assimp: {
+    command: "assimp",
+    args: ["version"],
+    timeout: 5000,
+  },
+  dasel: {
+    command: "dasel",
+    args: ["--version"],
+    timeout: 2000,
+  },
+};
+
+/**
+ * 引擎預調用管理器
+ */
+export class EngineWarmupManager {
+  /** 當前預調用狀態 */
+  private currentWarmup: WarmupStatus | null = null;
+
+  /** 預調用 Promise */
+  private warmupPromise: Promise<void> | null = null;
+
+  /** 取消標記 */
+  private cancelRequested = false;
+
+  /**
+   * 開始預調用引擎
+   * 注意：同時只會有一個引擎被預調用
+   */
+  async warmup(engine: string): Promise<boolean> {
+    // 如果已經在預調用同一個引擎，直接返回
+    if (this.currentWarmup?.engine === engine && this.currentWarmup.status === "warming") {
+      return true;
+    }
+
+    // 取消之前的預調用
+    if (this.currentWarmup?.status === "warming") {
+      this.cancel();
+    }
+
+    // 檢查是否有該引擎的預調用命令
+    const warmupCmd = ENGINE_WARMUP_COMMANDS[engine];
+    if (!warmupCmd) {
+      console.warn(`No warmup command defined for engine: ${engine}`);
+      return false;
+    }
+
+    // 設定狀態
+    this.cancelRequested = false;
+    this.currentWarmup = {
+      engine,
+      status: "warming",
+      started_at: new Date().toISOString(),
+    };
+
+    console.log(`🔥 Warming up engine: ${engine}`);
+
+    // 執行預調用
+    this.warmupPromise = this.executeWarmup(engine, warmupCmd);
+
+    try {
+      await this.warmupPromise;
+      return this.currentWarmup?.status === "ready";
+    } catch {
+      return false;
+    }
+  }
+
+  /**
+   * 執行預調用命令
+   */
+  private async executeWarmup(engine: string, cmd: WarmupCommand): Promise<void> {
+    try {
+      // 檢查是否已取消
+      if (this.cancelRequested) {
+        this.updateStatus("cancelled");
+        return;
+      }
+
+      await execFileAsync(cmd.command, cmd.args, {
+        timeout: cmd.timeout,
+      });
+
+      // 再次檢查是否已取消
+      if (this.cancelRequested) {
+        this.updateStatus("cancelled");
+        return;
+      }
+
+      this.updateStatus("ready");
+      console.log(`✅ Engine ${engine} warmed up successfully`);
+    } catch (error) {
+      if (this.cancelRequested) {
+        this.updateStatus("cancelled");
+        return;
+      }
+
+      this.updateStatus("failed", error instanceof Error ? error.message : "Unknown error");
+      console.warn(`⚠️ Failed to warm up engine ${engine}:`, error);
+    }
+  }
+
+  /**
+   * 更新預調用狀態
+   */
+  private updateStatus(status: WarmupStatus["status"], error?: string): void {
+    if (this.currentWarmup) {
+      this.currentWarmup.status = status;
+      if (status === "ready" || status === "failed" || status === "cancelled") {
+        this.currentWarmup.completed_at = new Date().toISOString();
+      }
+      if (error) {
+        this.currentWarmup.error = error;
+      }
+    }
+  }
+
+  /**
+   * 取消當前預調用
+   */
+  cancel(): void {
+    if (this.currentWarmup?.status === "warming") {
+      console.log(`❌ Cancelling warmup for engine: ${this.currentWarmup.engine}`);
+      this.cancelRequested = true;
+      this.updateStatus("cancelled");
+    }
+  }
+
+  /**
+   * 取得當前預調用狀態
+   */
+  getStatus(): WarmupStatus | null {
+    return this.currentWarmup;
+  }
+
+  /**
+   * 檢查引擎是否已預調用完成
+   */
+  isReady(engine: string): boolean {
+    return this.currentWarmup?.engine === engine && this.currentWarmup.status === "ready";
+  }
+
+  /**
+   * 重置狀態
+   */
+  reset(): void {
+    this.cancel();
+    this.currentWarmup = null;
+    this.warmupPromise = null;
+    this.cancelRequested = false;
+  }
+}
+
+// 導出單例
+export const engineWarmupManager = new EngineWarmupManager();
diff --git a/src/inference/featureExtraction.ts b/src/inference/featureExtraction.ts
new file mode 100644
index 0000000..ec1b0e3
--- /dev/null
+++ b/src/inference/featureExtraction.ts
@@ -0,0 +1,429 @@
+/**
+ * 檔案特徵抽取模組
+ *
+ * 從上傳的檔案中提取用於格式推斷的特徵
+ */
+
+import { execFile } from "node:child_process";
+import { promisify } from "node:util";
+import { stat } from "node:fs/promises";
+
+const execFileAsync = promisify(execFile);
+
+/**
+ * 基礎檔案特徵
+ */
+export interface BaseFileFeatures {
+  /** 輸入檔案副檔名 (不含點) */
+  input_ext: string;
+  /** MIME 類型 */
+  mime_type: string;
+  /** 檔案大小 (KB) */
+  file_size_kb: number;
+  /** 魔數家族 (image/video/audio/document/data/model3d/archive/font/unknown) */
+  magic_family: string;
+  /** 上傳時段 (morning/afternoon/evening/night) */
+  upload_hour_bucket: string;
+}
+
+/**
+ * 圖片專用特徵
+ */
+export interface ImageFeatures {
+  /** 寬度 (像素) */
+  width: number;
+  /** 高度 (像素) */
+  height: number;
+  /** 百萬像素 */
+  megapixels: number;
+  /** 是否有透明通道 */
+  has_alpha: boolean;
+  /** 是否為動畫 */
+  is_animation: boolean;
+  /** 色彩模式 (rgb/rgba/cmyk/grayscale) */
+  color_mode: string;
+  /** 長寬比描述 */
+  aspect_ratio: string;
+}
+
+/**
+ * 完整檔案特徵
+ */
+export interface FileFeatures extends BaseFileFeatures {
+  /** 圖片專用特徵 (僅當 magic_family === 'image' 時存在) */
+  image?: ImageFeatures;
+}
+
+/**
+ * 副檔名到 magic_family 的映射
+ */
+const EXT_TO_FAMILY: Record<string, string> = {
+  // 圖片
+  jpg: "image",
+  jpeg: "image",
+  png: "image",
+  gif: "image",
+  webp: "image",
+  avif: "image",
+  heic: "image",
+  heif: "image",
+  bmp: "image",
+  tiff: "image",
+  tif: "image",
+  svg: "image",
+  ico: "image",
+  icns: "image",
+  psd: "image",
+  raw: "image",
+  cr2: "image",
+  cr3: "image",
+  nef: "image",
+  arw: "image",
+  dng: "image",
+  orf: "image",
+  rw2: "image",
+  jxl: "image",
+  apng: "image",
+  eps: "image",
+  ai: "image",
+  emf: "image",
+  wmf: "image",
+  cur: "image",
+
+  // 影片
+  mp4: "video",
+  mkv: "video",
+  avi: "video",
+  mov: "video",
+  webm: "video",
+  flv: "video",
+  wmv: "video",
+  m4v: "video",
+  "3gp": "video",
+  mpeg: "video",
+  mpg: "video",
+  mts: "video",
+  m2ts: "video",
+  vob: "video",
+  ogv: "video",
+  prores: "video",
+  mxf: "video",
+
+  // 音訊
+  mp3: "audio",
+  wav: "audio",
+  flac: "audio",
+  aac: "audio",
+  ogg: "audio",
+  m4a: "audio",
+  wma: "audio",
+  opus: "audio",
+  aiff: "audio",
+  ape: "audio",
+  alac: "audio",
+  mid: "audio",
+  midi: "audio",
+
+  // 文件
+  pdf: "document",
+  doc: "document",
+  docx: "document",
+  odt: "document",
+  rtf: "document",
+  txt: "document",
+  xls: "document",
+  xlsx: "document",
+  ods: "document",
+  ppt: "document",
+  pptx: "document",
+  odp: "document",
+  epub: "document",
+  mobi: "document",
+  azw3: "document",
+  fb2: "document",
+  md: "document",
+  markdown: "document",
+  rst: "document",
+  tex: "document",
+  html: "document",
+  htm: "document",
+  key: "document",
+  pages: "document",
+  numbers: "document",
+  msg: "document",
+  eml: "document",
+
+  // 資料
+  json: "data",
+  yaml: "data",
+  yml: "data",
+  xml: "data",
+  csv: "data",
+  toml: "data",
+  ini: "data",
+  vcf: "data",
+
+  // 3D 模型
+  obj: "model3d",
+  fbx: "model3d",
+  gltf: "model3d",
+  glb: "model3d",
+  stl: "model3d",
+  dae: "model3d",
+  ply: "model3d",
+  "3ds": "model3d",
+  blend: "model3d",
+
+  // 壓縮檔
+  zip: "archive",
+  tar: "archive",
+  gz: "archive",
+  "7z": "archive",
+  rar: "archive",
+  bz2: "archive",
+  xz: "archive",
+
+  // 字型
+  ttf: "font",
+  otf: "font",
+  woff: "font",
+  woff2: "font",
+  eot: "font",
+};
+
+/**
+ * 副檔名到 MIME 類型的映射
+ */
+const EXT_TO_MIME: Record<string, string> = {
+  jpg: "image/jpeg",
+  jpeg: "image/jpeg",
+  png: "image/png",
+  gif: "image/gif",
+  webp: "image/webp",
+  avif: "image/avif",
+  heic: "image/heic",
+  heif: "image/heif",
+  bmp: "image/bmp",
+  tiff: "image/tiff",
+  tif: "image/tiff",
+  svg: "image/svg+xml",
+  ico: "image/x-icon",
+  psd: "image/vnd.adobe.photoshop",
+  jxl: "image/jxl",
+
+  mp4: "video/mp4",
+  mkv: "video/x-matroska",
+  avi: "video/x-msvideo",
+  mov: "video/quicktime",
+  webm: "video/webm",
+  flv: "video/x-flv",
+
+  mp3: "audio/mpeg",
+  wav: "audio/wav",
+  flac: "audio/flac",
+  aac: "audio/aac",
+  ogg: "audio/ogg",
+  m4a: "audio/mp4",
+  opus: "audio/opus",
+
+  pdf: "application/pdf",
+  doc: "application/msword",
+  docx: "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+  json: "application/json",
+  xml: "application/xml",
+  csv: "text/csv",
+  txt: "text/plain",
+  html: "text/html",
+  md: "text/markdown",
+};
+
+/**
+ * 根據小時數取得時段
+ */
+function getHourBucket(hour: number): string {
+  if (hour >= 6 && hour < 12) return "morning";
+  if (hour >= 12 && hour < 18) return "afternoon";
+  if (hour >= 18 && hour < 22) return "evening";
+  return "night";
+}
+
+/**
+ * 計算長寬比描述
+ */
+function getAspectRatio(width: number, height: number): string {
+  const ratio = width / height;
+  if (Math.abs(ratio - 1) < 0.05) return "1:1";
+  if (Math.abs(ratio - 4 / 3) < 0.1) return "4:3";
+  if (Math.abs(ratio - 3 / 4) < 0.1) return "3:4";
+  if (Math.abs(ratio - 16 / 9) < 0.1) return "16:9";
+  if (Math.abs(ratio - 9 / 16) < 0.1) return "9:16";
+  if (Math.abs(ratio - 3 / 2) < 0.1) return "3:2";
+  if (Math.abs(ratio - 2 / 3) < 0.1) return "2:3";
+  if (ratio > 2) return "panorama";
+  if (ratio < 0.5) return "tall";
+  return "other";
+}
+
+/**
+ * 使用 ImageMagick 提取圖片特徵
+ */
+async function extractImageFeaturesWithImageMagick(
+  filePath: string,
+): Promise<ImageFeatures | null> {
+  try {
+    const { stdout } = await execFileAsync("identify", [
+      "-format",
+      "%w|%h|%[channels]|%n|%[colorspace]",
+      filePath,
+    ]);
+
+    const parts = stdout.trim().split("|");
+    if (parts.length < 5) return null;
+
+    const width = parseInt(parts[0] ?? "0", 10);
+    const height = parseInt(parts[1] ?? "0", 10);
+    const channels = parts[2] ?? "";
+    const frameCount = parseInt(parts[3] ?? "0", 10);
+    const colorspace = (parts[4] ?? "").toLowerCase();
+
+    const megapixels = (width * height) / 1_000_000;
+    const has_alpha = channels.includes("a") || channels.includes("alpha");
+    const is_animation = frameCount > 1;
+
+    let color_mode = "rgb";
+    if (colorspace.includes("gray")) {
+      color_mode = "grayscale";
+    } else if (colorspace.includes("cmyk")) {
+      color_mode = "cmyk";
+    } else if (has_alpha) {
+      color_mode = "rgba";
+    }
+
+    return {
+      width,
+      height,
+      megapixels: Math.round(megapixels * 100) / 100,
+      has_alpha,
+      is_animation,
+      color_mode,
+      aspect_ratio: getAspectRatio(width, height),
+    };
+  } catch (error) {
+    console.warn("ImageMagick identify failed, trying vips...", error);
+    return null;
+  }
+}
+
+/**
+ * 使用 vips 提取圖片特徵 (備用)
+ */
+async function extractImageFeaturesWithVips(filePath: string): Promise<ImageFeatures | null> {
+  try {
+    const { stdout } = await execFileAsync("vipsheader", ["-a", filePath]);
+
+    const lines = stdout.trim().split("\n");
+    let width = 0,
+      height = 0,
+      bands = 3;
+
+    for (const line of lines) {
+      const [key, value] = line.split(":").map((s) => s.trim());
+      if (key === "width" && value) width = parseInt(value, 10);
+      if (key === "height" && value) height = parseInt(value, 10);
+      if (key === "bands" && value) bands = parseInt(value, 10);
+    }
+
+    if (width === 0 || height === 0) return null;
+
+    const megapixels = (width * height) / 1_000_000;
+    const has_alpha = bands === 4;
+
+    return {
+      width,
+      height,
+      megapixels: Math.round(megapixels * 100) / 100,
+      has_alpha,
+      is_animation: false, // vipsheader doesn't easily detect animation
+      color_mode: has_alpha ? "rgba" : "rgb",
+      aspect_ratio: getAspectRatio(width, height),
+    };
+  } catch (error) {
+    console.warn("vipsheader failed:", error);
+    return null;
+  }
+}
+
+/**
+ * 提取圖片特徵
+ */
+async function extractImageFeatures(filePath: string): Promise<ImageFeatures | null> {
+  // 優先使用 ImageMagick
+  let features = await extractImageFeaturesWithImageMagick(filePath);
+  if (features) return features;
+
+  // 備用使用 vips
+  features = await extractImageFeaturesWithVips(filePath);
+  return features;
+}
+
+/**
+ * 從檔案路徑提取完整特徵
+ */
+export async function extractFeatures(filePath: string): Promise<FileFeatures> {
+  // 取得副檔名
+  const ext = filePath.split(".").pop()?.toLowerCase() ?? "";
+
+  // 取得檔案大小
+  let fileSizeKb = 0;
+  try {
+    const stats = await stat(filePath);
+    fileSizeKb = Math.round(stats.size / 1024);
+  } catch {
+    console.warn("Could not stat file:", filePath);
+  }
+
+  // 決定 magic_family
+  const magicFamily = EXT_TO_FAMILY[ext] ?? "unknown";
+
+  // 決定 MIME 類型
+  const mimeType = EXT_TO_MIME[ext] ?? "application/octet-stream";
+
+  // 取得時段
+  const uploadHourBucket = getHourBucket(new Date().getHours());
+
+  const baseFeatures: FileFeatures = {
+    input_ext: ext,
+    mime_type: mimeType,
+    file_size_kb: fileSizeKb,
+    magic_family: magicFamily,
+    upload_hour_bucket: uploadHourBucket,
+  };
+
+  // 如果是圖片，提取圖片特徵
+  if (magicFamily === "image") {
+    const imageFeatures = await extractImageFeatures(filePath);
+    if (imageFeatures) {
+      baseFeatures.image = imageFeatures;
+    }
+  }
+
+  return baseFeatures;
+}
+
+/**
+ * 從副檔名快速提取基礎特徵 (不需要實際檔案)
+ * 用於前端快速推斷
+ */
+export function extractFeaturesFromExtension(ext: string): Omit<FileFeatures, "file_size_kb"> {
+  const cleanExt = ext.toLowerCase().replace(/^\./, "");
+  const magicFamily = EXT_TO_FAMILY[cleanExt] ?? "unknown";
+  const mimeType = EXT_TO_MIME[cleanExt] ?? "application/octet-stream";
+  const uploadHourBucket = getHourBucket(new Date().getHours());
+
+  return {
+    input_ext: cleanExt,
+    mime_type: mimeType,
+    magic_family: magicFamily,
+    upload_hour_bucket: uploadHourBucket,
+  };
+}
diff --git a/src/inference/formatCandidateRules.ts b/src/inference/formatCandidateRules.ts
new file mode 100644
index 0000000..0eff1a4
--- /dev/null
+++ b/src/inference/formatCandidateRules.ts
@@ -0,0 +1,512 @@
+/**
+ * 格式候選規則配置檔
+ *
+ * 本模組定義了基於檔案特徵的格式候選生成規則
+ * 用於將 1000+ 格式空間降維為 10～30 個候選格式
+ */
+
+export interface FormatCandidateRule {
+  /** 規則ID */
+  id: string;
+  /** 觸發條件 */
+  conditions: {
+    magic_family?: string;
+    has_alpha?: boolean;
+    is_animation?: boolean;
+    input_ext?: string | string[];
+    min_megapixels?: number;
+    max_megapixels?: number;
+    color_mode?: string;
+  };
+  /** 候選格式及其先驗權重 (0-1) */
+  candidates: Record<string, number>;
+  /** 規則原因碼 */
+  reason_code: string;
+  /** 規則優先級 (數字越大優先級越高) */
+  priority: number;
+}
+
+/**
+ * 格式候選規則庫
+ * 規則按優先級排序，高優先級規則先匹配
+ */
+export const formatCandidateRules: FormatCandidateRule[] = [
+  // ==================== 圖片格式規則 ====================
+  {
+    id: "image_alpha",
+    conditions: { magic_family: "image", has_alpha: true },
+    candidates: {
+      png: 1.0,
+      webp: 0.9,
+      avif: 0.7,
+      tiff: 0.4,
+      gif: 0.3,
+    },
+    reason_code: "IMG_ALPHA",
+    priority: 100,
+  },
+  {
+    id: "image_animation",
+    conditions: { magic_family: "image", is_animation: true },
+    candidates: {
+      gif: 1.0,
+      webp: 0.9,
+      mp4: 0.6,
+      apng: 0.5,
+    },
+    reason_code: "IMG_ANIM",
+    priority: 100,
+  },
+  {
+    id: "image_high_res",
+    conditions: { magic_family: "image", min_megapixels: 10 },
+    candidates: {
+      webp: 1.0,
+      avif: 0.95,
+      jpeg: 0.85,
+      jxl: 0.8,
+      png: 0.6,
+      heif: 0.5,
+    },
+    reason_code: "IMG_HIGHRES",
+    priority: 90,
+  },
+  {
+    id: "image_photo_raw",
+    conditions: {
+      magic_family: "image",
+      input_ext: ["raw", "cr2", "cr3", "nef", "arw", "dng", "orf", "rw2"],
+    },
+    candidates: {
+      jpeg: 1.0,
+      png: 0.8,
+      tiff: 0.7,
+      webp: 0.6,
+    },
+    reason_code: "IMG_RAW",
+    priority: 95,
+  },
+  {
+    id: "image_vector_input",
+    conditions: {
+      magic_family: "image",
+      input_ext: ["svg", "eps", "ai", "emf", "wmf"],
+    },
+    candidates: {
+      svg: 1.0,
+      png: 0.9,
+      pdf: 0.8,
+      eps: 0.6,
+    },
+    reason_code: "IMG_VECTOR",
+    priority: 95,
+  },
+  {
+    id: "image_icon",
+    conditions: {
+      magic_family: "image",
+      input_ext: ["ico", "icns", "cur"],
+    },
+    candidates: {
+      png: 1.0,
+      ico: 0.9,
+      svg: 0.5,
+    },
+    reason_code: "IMG_ICON",
+    priority: 95,
+  },
+  {
+    id: "image_default",
+    conditions: { magic_family: "image" },
+    candidates: {
+      png: 0.9,
+      jpeg: 0.85,
+      webp: 0.8,
+      avif: 0.7,
+      pdf: 0.4,
+      gif: 0.3,
+      tiff: 0.25,
+      bmp: 0.2,
+    },
+    reason_code: "IMG_BASE",
+    priority: 10,
+  },
+
+  // ==================== 影片格式規則 ====================
+  {
+    id: "video_default",
+    conditions: { magic_family: "video" },
+    candidates: {
+      mp4: 1.0,
+      webm: 0.8,
+      mkv: 0.7,
+      avi: 0.5,
+      mov: 0.5,
+      gif: 0.4,
+      mp3: 0.35,
+      wav: 0.25,
+    },
+    reason_code: "VID_BASE",
+    priority: 10,
+  },
+  {
+    id: "video_high_quality",
+    conditions: {
+      magic_family: "video",
+      input_ext: ["mov", "prores", "mxf"],
+    },
+    candidates: {
+      mp4: 1.0,
+      mkv: 0.9,
+      webm: 0.7,
+      prores: 0.6,
+    },
+    reason_code: "VID_HQ",
+    priority: 80,
+  },
+
+  // ==================== 音訊格式規則 ====================
+  {
+    id: "audio_default",
+    conditions: { magic_family: "audio" },
+    candidates: {
+      mp3: 1.0,
+      wav: 0.8,
+      flac: 0.7,
+      aac: 0.65,
+      ogg: 0.6,
+      m4a: 0.55,
+      opus: 0.5,
+    },
+    reason_code: "AUD_BASE",
+    priority: 10,
+  },
+  {
+    id: "audio_lossless",
+    conditions: {
+      magic_family: "audio",
+      input_ext: ["flac", "wav", "alac", "ape", "aiff"],
+    },
+    candidates: {
+      flac: 1.0,
+      wav: 0.9,
+      mp3: 0.8,
+      aac: 0.7,
+      alac: 0.6,
+    },
+    reason_code: "AUD_LOSSLESS",
+    priority: 80,
+  },
+
+  // ==================== 文件格式規則 ====================
+  {
+    id: "document_office",
+    conditions: {
+      magic_family: "document",
+      input_ext: ["doc", "docx", "odt", "rtf"],
+    },
+    candidates: {
+      pdf: 1.0,
+      docx: 0.9,
+      odt: 0.7,
+      txt: 0.5,
+      html: 0.4,
+      md: 0.3,
+    },
+    reason_code: "DOC_OFFICE",
+    priority: 80,
+  },
+  {
+    id: "document_spreadsheet",
+    conditions: {
+      magic_family: "document",
+      input_ext: ["xls", "xlsx", "ods", "csv"],
+    },
+    candidates: {
+      xlsx: 1.0,
+      csv: 0.9,
+      ods: 0.7,
+      pdf: 0.6,
+      json: 0.4,
+    },
+    reason_code: "DOC_SHEET",
+    priority: 80,
+  },
+  {
+    id: "document_presentation",
+    conditions: {
+      magic_family: "document",
+      input_ext: ["ppt", "pptx", "odp", "key"],
+    },
+    candidates: {
+      pdf: 1.0,
+      pptx: 0.9,
+      odp: 0.7,
+      png: 0.5,
+    },
+    reason_code: "DOC_PRES",
+    priority: 80,
+  },
+  {
+    id: "document_pdf",
+    conditions: {
+      magic_family: "document",
+      input_ext: ["pdf"],
+    },
+    candidates: {
+      docx: 0.9,
+      txt: 0.85,
+      png: 0.8,
+      jpeg: 0.7,
+      html: 0.6,
+      md: 0.55,
+      epub: 0.4,
+    },
+    reason_code: "DOC_PDF",
+    priority: 85,
+  },
+  {
+    id: "document_ebook",
+    conditions: {
+      magic_family: "document",
+      input_ext: ["epub", "mobi", "azw3", "fb2"],
+    },
+    candidates: {
+      epub: 1.0,
+      mobi: 0.9,
+      pdf: 0.85,
+      azw3: 0.7,
+      txt: 0.5,
+    },
+    reason_code: "DOC_EBOOK",
+    priority: 80,
+  },
+  {
+    id: "document_markdown",
+    conditions: {
+      magic_family: "document",
+      input_ext: ["md", "markdown", "rst", "txt"],
+    },
+    candidates: {
+      pdf: 1.0,
+      html: 0.9,
+      docx: 0.8,
+      txt: 0.7,
+      epub: 0.5,
+    },
+    reason_code: "DOC_MD",
+    priority: 80,
+  },
+  {
+    id: "document_default",
+    conditions: { magic_family: "document" },
+    candidates: {
+      pdf: 1.0,
+      docx: 0.8,
+      txt: 0.7,
+      html: 0.5,
+    },
+    reason_code: "DOC_BASE",
+    priority: 10,
+  },
+
+  // ==================== 資料格式規則 ====================
+  {
+    id: "data_json",
+    conditions: {
+      magic_family: "data",
+      input_ext: ["json"],
+    },
+    candidates: {
+      yaml: 1.0,
+      xml: 0.8,
+      csv: 0.7,
+      toml: 0.6,
+    },
+    reason_code: "DATA_JSON",
+    priority: 80,
+  },
+  {
+    id: "data_yaml",
+    conditions: {
+      magic_family: "data",
+      input_ext: ["yaml", "yml"],
+    },
+    candidates: {
+      json: 1.0,
+      xml: 0.7,
+      toml: 0.6,
+    },
+    reason_code: "DATA_YAML",
+    priority: 80,
+  },
+  {
+    id: "data_xml",
+    conditions: {
+      magic_family: "data",
+      input_ext: ["xml"],
+    },
+    candidates: {
+      json: 1.0,
+      yaml: 0.8,
+      csv: 0.5,
+    },
+    reason_code: "DATA_XML",
+    priority: 80,
+  },
+  {
+    id: "data_default",
+    conditions: { magic_family: "data" },
+    candidates: {
+      json: 1.0,
+      csv: 0.8,
+      yaml: 0.7,
+      xml: 0.6,
+    },
+    reason_code: "DATA_BASE",
+    priority: 10,
+  },
+
+  // ==================== 3D 模型格式規則 ====================
+  {
+    id: "model3d_default",
+    conditions: { magic_family: "model3d" },
+    candidates: {
+      obj: 1.0,
+      fbx: 0.9,
+      gltf: 0.85,
+      glb: 0.8,
+      stl: 0.7,
+      dae: 0.6,
+      ply: 0.5,
+    },
+    reason_code: "3D_BASE",
+    priority: 10,
+  },
+
+  // ==================== 壓縮檔規則 ====================
+  {
+    id: "archive_default",
+    conditions: { magic_family: "archive" },
+    candidates: {
+      zip: 1.0,
+      tar: 0.8,
+      "7z": 0.75,
+      rar: 0.6,
+    },
+    reason_code: "ARC_BASE",
+    priority: 10,
+  },
+
+  // ==================== 字型格式規則 ====================
+  {
+    id: "font_default",
+    conditions: { magic_family: "font" },
+    candidates: {
+      woff2: 1.0,
+      woff: 0.9,
+      ttf: 0.85,
+      otf: 0.8,
+      eot: 0.5,
+    },
+    reason_code: "FONT_BASE",
+    priority: 10,
+  },
+];
+
+/**
+ * 根據檔案特徵生成候選格式
+ * @param features 檔案特徵
+ * @returns 候選格式及權重
+ */
+export function generateCandidates(features: {
+  input_ext: string;
+  magic_family: string;
+  has_alpha?: boolean;
+  is_animation?: boolean;
+  megapixels?: number;
+  color_mode?: string;
+}): { candidates: Record<string, number>; matched_rules: string[] } {
+  const sortedRules = [...formatCandidateRules].sort((a, b) => b.priority - a.priority);
+  const mergedCandidates: Record<string, number> = {};
+  const matchedRules: string[] = [];
+
+  for (const rule of sortedRules) {
+    if (matchesConditions(features, rule.conditions)) {
+      matchedRules.push(rule.id);
+
+      // 合併候選格式，取較高權重
+      for (const [format, weight] of Object.entries(rule.candidates)) {
+        if (!mergedCandidates[format] || mergedCandidates[format] < weight) {
+          mergedCandidates[format] = weight;
+        }
+      }
+    }
+  }
+
+  // 排除自身格式
+  delete mergedCandidates[features.input_ext];
+
+  return { candidates: mergedCandidates, matched_rules: matchedRules };
+}
+
+/**
+ * 檢查特徵是否匹配規則條件
+ */
+function matchesConditions(
+  features: {
+    input_ext: string;
+    magic_family: string;
+    has_alpha?: boolean;
+    is_animation?: boolean;
+    megapixels?: number;
+    color_mode?: string;
+  },
+  conditions: FormatCandidateRule["conditions"],
+): boolean {
+  // 檢查 magic_family
+  if (conditions.magic_family && features.magic_family !== conditions.magic_family) {
+    return false;
+  }
+
+  // 檢查 has_alpha
+  if (conditions.has_alpha !== undefined && features.has_alpha !== conditions.has_alpha) {
+    return false;
+  }
+
+  // 檢查 is_animation
+  if (conditions.is_animation !== undefined && features.is_animation !== conditions.is_animation) {
+    return false;
+  }
+
+  // 檢查 input_ext
+  if (conditions.input_ext) {
+    const extList = Array.isArray(conditions.input_ext)
+      ? conditions.input_ext
+      : [conditions.input_ext];
+    if (!extList.includes(features.input_ext)) {
+      return false;
+    }
+  }
+
+  // 檢查 min_megapixels
+  if (conditions.min_megapixels !== undefined) {
+    if (!features.megapixels || features.megapixels < conditions.min_megapixels) {
+      return false;
+    }
+  }
+
+  // 檢查 max_megapixels
+  if (conditions.max_megapixels !== undefined) {
+    if (!features.megapixels || features.megapixels > conditions.max_megapixels) {
+      return false;
+    }
+  }
+
+  // 檢查 color_mode
+  if (conditions.color_mode && features.color_mode !== conditions.color_mode) {
+    return false;
+  }
+
+  return true;
+}
diff --git a/src/inference/formatPredictionModel.ts b/src/inference/formatPredictionModel.ts
new file mode 100644
index 0000000..2444d52
--- /dev/null
+++ b/src/inference/formatPredictionModel.ts
@@ -0,0 +1,325 @@
+/**
+ * 格式預測模型
+ *
+ * 基於使用者行為歷史和檔案特徵預測最可能的目標格式
+ * 使用輕量級的邏輯回歸模型 + 規則融合
+ */
+
+import { generateCandidates } from "./formatCandidateRules";
+import type { FileFeatures } from "./featureExtraction";
+import type { UserProfile, FormatConversionStats } from "./behaviorStore";
+
+/**
+ * 格式預測結果
+ */
+export interface FormatPrediction {
+  /** 預測的搜尋格式 */
+  search_format: string;
+  /** 預測信心度 (0-1) */
+  confidence: number;
+  /** Top-K 候選格式 */
+  top_k: Array<{ format: string; score: number }>;
+  /** 預測原因碼 */
+  reason_codes: string[];
+}
+
+/**
+ * 模型權重配置
+ */
+export interface ModelWeights {
+  /** 使用者歷史權重 */
+  user_history_weight: number;
+  /** 規則先驗權重 */
+  rule_prior_weight: number;
+  /** 全域流行度權重 */
+  global_popularity_weight: number;
+  /** 最近使用權重 */
+  recency_weight: number;
+  /** 檔案特徵權重 */
+  feature_weight: number;
+}
+
+/**
+ * 預設模型權重
+ */
+const DEFAULT_WEIGHTS: ModelWeights = {
+  user_history_weight: 0.45,
+  rule_prior_weight: 0.25,
+  global_popularity_weight: 0.15,
+  recency_weight: 0.1,
+  feature_weight: 0.05,
+};
+
+/**
+ * 全域格式流行度 (預設值，會被實際統計覆蓋)
+ */
+const DEFAULT_GLOBAL_POPULARITY: Record<string, number> = {
+  png: 0.85,
+  jpeg: 0.8,
+  pdf: 0.75,
+  mp4: 0.7,
+  webp: 0.65,
+  mp3: 0.6,
+  docx: 0.55,
+  gif: 0.5,
+  svg: 0.45,
+  wav: 0.4,
+  xlsx: 0.35,
+  txt: 0.3,
+  json: 0.25,
+};
+
+/**
+ * 格式預測模型類
+ */
+export class FormatPredictionModel {
+  private weights: ModelWeights;
+  private globalPopularity: Record<string, number>;
+  private minConfidenceThreshold: number;
+
+  constructor(
+    weights: Partial<ModelWeights> = {},
+    globalPopularity: Record<string, number> = DEFAULT_GLOBAL_POPULARITY,
+    minConfidenceThreshold = 0.4,
+  ) {
+    this.weights = { ...DEFAULT_WEIGHTS, ...weights };
+    this.globalPopularity = globalPopularity;
+    this.minConfidenceThreshold = minConfidenceThreshold;
+  }
+
+  /**
+   * 預測最可能的目標格式
+   */
+  predict(
+    features: FileFeatures,
+    userProfile: UserProfile | null,
+    globalStats?: FormatConversionStats,
+  ): FormatPrediction | null {
+    // 第一步：生成候選格式
+    const candidateInput: {
+      input_ext: string;
+      magic_family: string;
+      has_alpha?: boolean;
+      is_animation?: boolean;
+      megapixels?: number;
+      color_mode?: string;
+    } = {
+      input_ext: features.input_ext,
+      magic_family: features.magic_family,
+    };
+
+    if (features.image?.has_alpha !== undefined) {
+      candidateInput.has_alpha = features.image.has_alpha;
+    }
+    if (features.image?.is_animation !== undefined) {
+      candidateInput.is_animation = features.image.is_animation;
+    }
+    if (features.image?.megapixels !== undefined) {
+      candidateInput.megapixels = features.image.megapixels;
+    }
+    if (features.image?.color_mode !== undefined) {
+      candidateInput.color_mode = features.image.color_mode;
+    }
+
+    const { candidates, matched_rules } = generateCandidates(candidateInput);
+
+    if (Object.keys(candidates).length === 0) {
+      return null;
+    }
+
+    // 第二步：計算每個候選格式的得分
+    const scoredFormats: Array<{
+      format: string;
+      score: number;
+      components: Record<string, number>;
+    }> = [];
+
+    for (const [format, rulePrior] of Object.entries(candidates)) {
+      const components: Record<string, number> = {};
+
+      // 1. 規則先驗分數
+      components.rule_prior = rulePrior * this.weights.rule_prior_weight;
+
+      // 2. 使用者歷史偏好分數
+      components.user_history =
+        this.calculateUserHistoryScore(features.input_ext, format, userProfile) *
+        this.weights.user_history_weight;
+
+      // 3. 全域流行度分數
+      const globalPop =
+        globalStats?.format_popularity?.[format] ?? this.globalPopularity[format] ?? 0.1;
+      components.global_popularity = globalPop * this.weights.global_popularity_weight;
+
+      // 4. 最近使用分數
+      components.recency =
+        this.calculateRecencyScore(format, userProfile) * this.weights.recency_weight;
+
+      // 5. 檔案特徵分數
+      components.feature =
+        this.calculateFeatureScore(features, format) * this.weights.feature_weight;
+
+      // 總分
+      const totalScore = Object.values(components).reduce((a, b) => a + b, 0);
+
+      scoredFormats.push({
+        format,
+        score: totalScore,
+        components,
+      });
+    }
+
+    // 排序並取 Top-K
+    scoredFormats.sort((a, b) => b.score - a.score);
+    const topK = scoredFormats.slice(0, 5).map((s) => ({
+      format: s.format,
+      score: Math.round(s.score * 100) / 100,
+    }));
+
+    // 最高分的格式
+    const topFormat = scoredFormats[0];
+    if (!topFormat) {
+      return null;
+    }
+
+    // 計算信心度 (使用 softmax 正規化後的相對優勢)
+    const confidence = this.calculateConfidence(scoredFormats);
+
+    // 如果信心度低於閾值，不推薦
+    if (confidence < this.minConfidenceThreshold) {
+      return null;
+    }
+
+    return {
+      search_format: topFormat.format,
+      confidence: Math.round(confidence * 100) / 100,
+      top_k: topK,
+      reason_codes: matched_rules,
+    };
+  }
+
+  /**
+   * 計算使用者歷史偏好分數
+   */
+  private calculateUserHistoryScore(
+    inputExt: string,
+    targetFormat: string,
+    userProfile: UserProfile | null,
+  ): number {
+    if (!userProfile) return 0;
+
+    const conversionKey = `${inputExt}->${targetFormat}`;
+    const preference = userProfile.format_preferences[conversionKey];
+
+    if (preference !== undefined) {
+      return preference;
+    }
+
+    // 檢查是否有任何以此格式為目標的記錄
+    let totalToFormat = 0;
+    let count = 0;
+    const entries = Object.entries(userProfile.format_preferences) as [string, number][];
+    for (const [key, value] of entries) {
+      if (key.endsWith(`->${targetFormat}`)) {
+        totalToFormat += value;
+        count++;
+      }
+    }
+
+    return count > 0 ? (totalToFormat / count) * 0.5 : 0;
+  }
+
+  /**
+   * 計算最近使用分數
+   */
+  private calculateRecencyScore(format: string, userProfile: UserProfile | null): number {
+    if (!userProfile?.recent_formats) return 0;
+
+    const recentFormats = userProfile.recent_formats;
+    const index = recentFormats.indexOf(format);
+
+    if (index === -1) return 0;
+
+    // 越近使用的分數越高
+    const recencyScore = 1 - index / recentFormats.length;
+    return recencyScore;
+  }
+
+  /**
+   * 計算檔案特徵分數
+   */
+  private calculateFeatureScore(features: FileFeatures, format: string): number {
+    let score = 0.5; // 基礎分
+
+    if (features.image) {
+      // 大圖優先考慮壓縮格式
+      if (features.image.megapixels > 10) {
+        if (["webp", "avif", "jxl", "heif"].includes(format)) {
+          score += 0.2;
+        }
+      }
+
+      // 有透明通道優先 PNG
+      if (features.image.has_alpha) {
+        if (format === "png" || format === "webp") {
+          score += 0.3;
+        }
+      }
+
+      // 動畫優先 GIF 或 WebP
+      if (features.image.is_animation) {
+        if (["gif", "webp", "apng"].includes(format)) {
+          score += 0.3;
+        }
+      }
+    }
+
+    return Math.min(score, 1);
+  }
+
+  /**
+   * 計算預測信心度
+   */
+  private calculateConfidence(scoredFormats: Array<{ format: string; score: number }>): number {
+    if (scoredFormats.length === 0) return 0;
+
+    const first = scoredFormats[0];
+    if (!first) return 0;
+    if (scoredFormats.length === 1) return first.score;
+
+    const topScore = first.score;
+    const secondScore = scoredFormats[1]?.score ?? 0;
+
+    // 使用相對優勢計算信心度
+    const gap = topScore - secondScore;
+    const relativeGap = gap / (topScore + 0.001);
+
+    // 結合絕對分數和相對優勢
+    const confidence = topScore * 0.6 + relativeGap * 0.4;
+
+    return Math.min(Math.max(confidence, 0), 1);
+  }
+
+  /**
+   * 更新模型權重 (用於線上學習)
+   */
+  updateWeights(newWeights: Partial<ModelWeights>): void {
+    this.weights = { ...this.weights, ...newWeights };
+  }
+
+  /**
+   * 更新全域流行度統計
+   */
+  updateGlobalPopularity(popularity: Record<string, number>): void {
+    this.globalPopularity = { ...this.globalPopularity, ...popularity };
+  }
+
+  /**
+   * 設定最低信心度閾值
+   */
+  setMinConfidenceThreshold(threshold: number): void {
+    this.minConfidenceThreshold = threshold;
+  }
+}
+
+// 導出單例
+export const formatPredictionModel = new FormatPredictionModel();
diff --git a/src/inference/index.ts b/src/inference/index.ts
new file mode 100644
index 0000000..545d238
--- /dev/null
+++ b/src/inference/index.ts
@@ -0,0 +1,14 @@
+/**
+ * 推斷模組統一導出
+ */
+
+export * from "./featureExtraction";
+export * from "./formatCandidateRules";
+export * from "./formatPredictionModel";
+export * from "./enginePredictionModel";
+export * from "./behaviorStore";
+export * from "./engineWarmup";
+export * from "./inferenceService";
+
+// 預設導出推斷服務
+export { inferenceService as default } from "./inferenceService";
diff --git a/src/inference/inferenceService.ts b/src/inference/inferenceService.ts
new file mode 100644
index 0000000..4899c44
--- /dev/null
+++ b/src/inference/inferenceService.ts
@@ -0,0 +1,343 @@
+/**
+ * 自動格式推斷服務
+ *
+ * 整合所有推斷模組，提供統一的推斷 API
+ */
+
+import {
+  extractFeatures,
+  extractFeaturesFromExtension,
+  type FileFeatures,
+} from "./featureExtraction";
+import {
+  FormatPredictionModel,
+  formatPredictionModel,
+  type FormatPrediction,
+} from "./formatPredictionModel";
+import {
+  EnginePredictionModel,
+  enginePredictionModel,
+  type EnginePrediction,
+} from "./enginePredictionModel";
+import {
+  initBehaviorTables,
+  getUserProfile,
+  logConversionEvent,
+  logDismissEvent,
+  calculateGlobalStats,
+  cleanupOldEvents,
+  type UserProfile,
+  type FormatConversionStats,
+} from "./behaviorStore";
+import { engineWarmupManager, type WarmupStatus } from "./engineWarmup";
+
+/**
+ * 完整推斷結果
+ */
+export interface InferenceResult {
+  /** 格式推斷結果 */
+  format: FormatPrediction | null;
+  /** 引擎推斷結果 */
+  engine: EnginePrediction | null;
+  /** 檔案特徵 */
+  features: FileFeatures;
+  /** 是否應自動填入 */
+  should_auto_fill: boolean;
+  /** 預調用狀態 */
+  warmup_status?: WarmupStatus | null;
+}
+
+/**
+ * 推斷服務配置
+ */
+export interface InferenceServiceConfig {
+  /** 格式推斷最低信心度閾值 */
+  formatConfidenceThreshold: number;
+  /** 引擎推斷最低信心度閾值 */
+  engineConfidenceThreshold: number;
+  /** 是否啟用預調用 */
+  enableWarmup: boolean;
+  /** 預調用最低信心度閾值 */
+  warmupConfidenceThreshold: number;
+}
+
+/**
+ * 預設配置
+ */
+const DEFAULT_CONFIG: InferenceServiceConfig = {
+  formatConfidenceThreshold: 0.4,
+  engineConfidenceThreshold: 0.5,
+  enableWarmup: true,
+  warmupConfidenceThreshold: 0.7,
+};
+
+/**
+ * 自動格式推斷服務類
+ */
+export class InferenceService {
+  private config: InferenceServiceConfig;
+  private formatModel: FormatPredictionModel;
+  private engineModel: EnginePredictionModel;
+  private globalStats: FormatConversionStats | null = null;
+  private initialized = false;
+
+  constructor(config: Partial<InferenceServiceConfig> = {}) {
+    this.config = { ...DEFAULT_CONFIG, ...config };
+    this.formatModel = formatPredictionModel;
+    this.engineModel = enginePredictionModel;
+
+    // 設定模型閾值
+    this.formatModel.setMinConfidenceThreshold(this.config.formatConfidenceThreshold);
+  }
+
+  /**
+   * 初始化服務
+   */
+  async initialize(): Promise<void> {
+    if (this.initialized) return;
+
+    try {
+      // 初始化行為資料表
+      initBehaviorTables();
+
+      // 載入全域統計
+      this.globalStats = calculateGlobalStats();
+
+      // 更新格式模型的流行度
+      if (this.globalStats?.format_popularity) {
+        this.formatModel.updateGlobalPopularity(this.globalStats.format_popularity);
+      }
+
+      this.initialized = true;
+      console.log("✅ Inference service initialized");
+    } catch (error) {
+      console.error("Failed to initialize inference service:", error);
+      throw error;
+    }
+  }
+
+  /**
+   * 根據檔案路徑進行推斷
+   */
+  async inferFromFile(
+    filePath: string,
+    userId: number,
+    availableEngines?: string[],
+  ): Promise<InferenceResult> {
+    // 確保已初始化
+    if (!this.initialized) {
+      await this.initialize();
+    }
+
+    // 提取檔案特徵
+    const features = await extractFeatures(filePath);
+
+    return this.inferFromFeatures(features, userId, availableEngines);
+  }
+
+  /**
+   * 根據副檔名快速推斷 (用於前端即時推斷)
+   */
+  async inferFromExtension(
+    ext: string,
+    userId: number,
+    fileSizeKb?: number,
+    availableEngines?: string[],
+  ): Promise<InferenceResult> {
+    // 確保已初始化
+    if (!this.initialized) {
+      await this.initialize();
+    }
+
+    // 從副檔名提取基礎特徵
+    const baseFeatures = extractFeaturesFromExtension(ext);
+    const features: FileFeatures = {
+      ...baseFeatures,
+      file_size_kb: fileSizeKb ?? 0,
+    };
+
+    return this.inferFromFeatures(features, userId, availableEngines);
+  }
+
+  /**
+   * 根據特徵進行推斷
+   */
+  private async inferFromFeatures(
+    features: FileFeatures,
+    userId: number,
+    availableEngines?: string[],
+  ): Promise<InferenceResult> {
+    // 取得使用者 Profile
+    const userProfile = getUserProfile(userId);
+
+    // 格式推斷
+    const formatPrediction = this.formatModel.predict(
+      features,
+      userProfile,
+      this.globalStats ?? undefined,
+    );
+
+    // 引擎推斷 (如果有格式預測)
+    let enginePrediction: EnginePrediction | null = null;
+    if (formatPrediction) {
+      enginePrediction = this.engineModel.predict(
+        formatPrediction.search_format,
+        features,
+        userProfile,
+        availableEngines,
+      );
+    }
+
+    // 決定是否自動填入
+    const shouldAutoFill =
+      formatPrediction !== null &&
+      formatPrediction.confidence >= this.config.formatConfidenceThreshold;
+
+    // 預調用處理
+    let warmupStatus: WarmupStatus | null = null;
+    if (
+      this.config.enableWarmup &&
+      enginePrediction?.should_warmup &&
+      enginePrediction.confidence >= this.config.warmupConfidenceThreshold
+    ) {
+      // 啟動預調用 (非阻塞)
+      engineWarmupManager.warmup(enginePrediction.engine).catch(console.error);
+      warmupStatus = engineWarmupManager.getStatus();
+    }
+
+    return {
+      format: formatPrediction,
+      engine: enginePrediction,
+      features,
+      should_auto_fill: shouldAutoFill,
+      warmup_status: warmupStatus,
+    };
+  }
+
+  /**
+   * 取消預調用 (當使用者行為與預測不一致時呼叫)
+   */
+  cancelWarmup(): void {
+    engineWarmupManager.cancel();
+  }
+
+  /**
+   * 記錄轉檔完成
+   */
+  logConversion(params: {
+    userId: number;
+    inputExt: string;
+    searchedFormat: string;
+    selectedEngine: string;
+    success: boolean;
+    durationMs: number;
+    fileSizeKb?: number;
+    megapixels?: number;
+  }): void {
+    const eventData: Parameters<typeof logConversionEvent>[0] = {
+      user_id: params.userId,
+      input_ext: params.inputExt,
+      searched_format: params.searchedFormat,
+      selected_engine: params.selectedEngine,
+      success: params.success,
+      duration_ms: params.durationMs,
+    };
+
+    if (params.fileSizeKb !== undefined) {
+      eventData.file_size_kb = params.fileSizeKb;
+    }
+    if (params.megapixels !== undefined) {
+      eventData.megapixels = params.megapixels;
+    }
+
+    logConversionEvent(eventData);
+
+    // 定期更新全域統計 (每 100 次轉檔)
+    this.maybeRefreshGlobalStats();
+  }
+
+  /**
+   * 記錄推薦被拒絕
+   */
+  logDismiss(params: {
+    userId: number;
+    inputExt: string;
+    dismissedFormat: string;
+    dismissedEngine?: string;
+  }): void {
+    const eventData: Parameters<typeof logDismissEvent>[0] = {
+      user_id: params.userId,
+      input_ext: params.inputExt,
+      dismissed_format: params.dismissedFormat,
+    };
+
+    if (params.dismissedEngine !== undefined) {
+      eventData.dismissed_engine = params.dismissedEngine;
+    }
+
+    logDismissEvent(eventData);
+
+    // 取消預調用
+    this.cancelWarmup();
+  }
+
+  /**
+   * 取得使用者 Profile
+   */
+  getUserProfile(userId: number): UserProfile | null {
+    return getUserProfile(userId);
+  }
+
+  /**
+   * 定期刷新全域統計
+   */
+  private refreshCounter = 0;
+  private maybeRefreshGlobalStats(): void {
+    this.refreshCounter++;
+    if (this.refreshCounter >= 100) {
+      this.refreshCounter = 0;
+      setTimeout(() => {
+        try {
+          this.globalStats = calculateGlobalStats();
+          if (this.globalStats?.format_popularity) {
+            this.formatModel.updateGlobalPopularity(this.globalStats.format_popularity);
+          }
+        } catch (error) {
+          console.error("Failed to refresh global stats:", error);
+        }
+      }, 100);
+    }
+  }
+
+  /**
+   * 清理過期資料
+   */
+  cleanup(daysToKeep = 90): number {
+    return cleanupOldEvents(daysToKeep);
+  }
+
+  /**
+   * 更新配置
+   */
+  updateConfig(config: Partial<InferenceServiceConfig>): void {
+    this.config = { ...this.config, ...config };
+    this.formatModel.setMinConfidenceThreshold(this.config.formatConfidenceThreshold);
+  }
+
+  /**
+   * 檢查引擎是否已預調用完成
+   */
+  isEngineReady(engine: string): boolean {
+    return engineWarmupManager.isReady(engine);
+  }
+
+  /**
+   * 取得預調用狀態
+   */
+  getWarmupStatus(): WarmupStatus | null {
+    return engineWarmupManager.getStatus();
+  }
+}
+
+// 導出單例
+export const inferenceService = new InferenceService();
diff --git a/src/pages/convert.tsx b/src/pages/convert.tsx
index 6ae9825..8f0a937 100644
--- a/src/pages/convert.tsx
+++ b/src/pages/convert.tsx
@@ -8,6 +8,7 @@ import { Jobs } from "../db/types";
 import { WEBROOT } from "../helpers/env";
 import { normalizeFiletype } from "../helpers/normalizeFiletype";
 import { userService } from "./user";
+import { inferenceService } from "../inference";
 
 export const convert = new Elysia().use(userService).post(
   "/convert",
@@ -67,6 +68,12 @@ export const convert = new Elysia().use(userService).post(
     );
 
     // Start the conversion process in the background
+    // 記錄轉檔開始時間
+    const conversionStartTime = Date.now();
+
+    // 取得輸入檔案的副檔名 (從第一個檔案)
+    const inputExt = fileNames[0]?.split(".").pop()?.toLowerCase() ?? "";
+
     handleConvert(fileNames, userUploadsDir, userOutputDir, convertTo, converterName, jobId)
       .then(() => {
         // All conversions are done, update the job status to 'completed'
@@ -74,11 +81,41 @@ export const convert = new Elysia().use(userService).post(
           db.query("UPDATE jobs SET status = 'completed' WHERE id = ?1").run(jobId.value);
         }
 
+        // 記錄轉檔行為 (用於推斷學習)
+        try {
+          const durationMs = Date.now() - conversionStartTime;
+          inferenceService.logConversion({
+            userId: parseInt(user.id, 10),
+            inputExt: inputExt,
+            searchedFormat: convertTo,
+            selectedEngine: converterName,
+            success: true,
+            durationMs: durationMs,
+          });
+        } catch (logError) {
+          console.warn("Failed to log conversion event:", logError);
+        }
+
         // Delete all uploaded files in userUploadsDir
         // rmSync(userUploadsDir, { recursive: true, force: true });
       })
       .catch((error) => {
         console.error("Error in conversion process:", error);
+
+        // 記錄失敗的轉檔
+        try {
+          const durationMs = Date.now() - conversionStartTime;
+          inferenceService.logConversion({
+            userId: parseInt(user.id, 10),
+            inputExt: inputExt,
+            searchedFormat: convertTo,
+            selectedEngine: converterName,
+            success: false,
+            durationMs: durationMs,
+          });
+        } catch (logError) {
+          console.warn("Failed to log conversion event:", logError);
+        }
       });
 
     // Redirect the client immediately
diff --git a/src/pages/inference.tsx b/src/pages/inference.tsx
new file mode 100644
index 0000000..eaf2fa3
--- /dev/null
+++ b/src/pages/inference.tsx
@@ -0,0 +1,139 @@
+/**
+ * 推斷 API 端點
+ *
+ * 提供前端呼叫的推斷 API
+ */
+
+import { Elysia, t } from "elysia";
+import { inferenceService } from "../inference";
+
+export const inferenceApi = new Elysia({ prefix: "/inference" })
+  /**
+   * 根據副檔名推斷最可能的目標格式和引擎
+   */
+  .post(
+    "/predict",
+    async ({ body, cookie: { user_id } }) => {
+      const userId = parseInt(String(user_id?.value ?? "0"), 10);
+
+      try {
+        const result = await inferenceService.inferFromExtension(
+          body.ext,
+          userId,
+          body.file_size_kb,
+          body.available_engines,
+        );
+
+        return {
+          success: true,
+          data: {
+            format: result.format,
+            engine: result.engine,
+            should_auto_fill: result.should_auto_fill,
+            warmup_status: result.warmup_status,
+          },
+        };
+      } catch (error) {
+        console.error("Inference prediction error:", error);
+        return {
+          success: false,
+          error: "Failed to predict format",
+        };
+      }
+    },
+    {
+      body: t.Object({
+        ext: t.String({ description: "輸入檔案副檔名" }),
+        file_size_kb: t.Optional(t.Number({ description: "檔案大小 (KB)" })),
+        available_engines: t.Optional(t.Array(t.String(), { description: "可用引擎列表" })),
+      }),
+    },
+  )
+
+  /**
+   * 記錄推薦被拒絕事件
+   */
+  .post(
+    "/dismiss",
+    async ({ body, cookie: { user_id } }) => {
+      const userId = parseInt(String(user_id?.value ?? "0"), 10);
+
+      try {
+        const dismissParams: {
+          userId: number;
+          inputExt: string;
+          dismissedFormat: string;
+          dismissedEngine?: string;
+        } = {
+          userId,
+          inputExt: body.input_ext,
+          dismissedFormat: body.dismissed_format,
+        };
+
+        if (body.dismissed_engine !== undefined) {
+          dismissParams.dismissedEngine = body.dismissed_engine;
+        }
+
+        inferenceService.logDismiss(dismissParams);
+
+        return { success: true };
+      } catch (error) {
+        console.error("Failed to log dismiss event:", error);
+        return { success: false };
+      }
+    },
+    {
+      body: t.Object({
+        input_ext: t.String({ description: "輸入檔案副檔名" }),
+        dismissed_format: t.String({ description: "被拒絕的推薦格式" }),
+        dismissed_engine: t.Optional(t.String({ description: "被拒絕的推薦引擎" })),
+      }),
+    },
+  )
+
+  /**
+   * 取消預調用
+   */
+  .post("/cancel-warmup", () => {
+    try {
+      inferenceService.cancelWarmup();
+      return { success: true };
+    } catch (error) {
+      console.error("Failed to cancel warmup:", error);
+      return { success: false };
+    }
+  })
+
+  /**
+   * 取得預調用狀態
+   */
+  .get("/warmup-status", () => {
+    try {
+      const status = inferenceService.getWarmupStatus();
+      return {
+        success: true,
+        data: status,
+      };
+    } catch (error) {
+      console.error("Failed to get warmup status:", error);
+      return { success: false, data: null };
+    }
+  })
+
+  /**
+   * 取得使用者 Profile
+   */
+  .get("/profile", ({ cookie: { user_id } }) => {
+    const userId = parseInt(String(user_id?.value ?? "0"), 10);
+
+    try {
+      const profile = inferenceService.getUserProfile(userId);
+      return {
+        success: true,
+        data: profile,
+      };
+    } catch (error) {
+      console.error("Failed to get user profile:", error);
+      return { success: false, data: null };
+    }
+  });