diff --git a/codex-lens/.env.example b/codex-lens/.env.example
index 1db45b70..67a5989b 100644
--- a/codex-lens/.env.example
+++ b/codex-lens/.env.example
@@ -1,10 +1,15 @@
 # CodexLens Environment Configuration
-# Copy this file to .codexlens/.env and fill in your values
-# 
-# Priority order:
-# 1. Environment variables (already set in shell)
-# 2. .codexlens/.env (workspace-local, this file)
+#
+# Configuration locations (copy to one of these):
+# - ~/.codexlens/.env      (global, applies to all projects)
+# - project/.codexlens/.env (workspace-local)
+# - project/.env           (project root)
+#
+# Priority order (later overrides earlier):
+# 1. Environment variables (already set in shell) - highest
+# 2. .codexlens/.env (workspace-local)
 # 3. .env (project root)
+# 4. ~/.codexlens/.env (global) - lowest
 
 # ============================================
 # RERANKER Configuration
diff --git a/codex-lens/docs/CONFIGURATION.md b/codex-lens/docs/CONFIGURATION.md
new file mode 100644
index 00000000..082ca933
--- /dev/null
+++ b/codex-lens/docs/CONFIGURATION.md
@@ -0,0 +1,265 @@
+# CodexLens 配置说明
+
+## 目录结构
+
+```
+~/.codexlens/                    # 全局数据目录
+├── .env                         # 全局 API 配置 (新增)
+├── settings.json                # 运行时设置
+├── embedding_lock.json          # 模型锁定文件
+├── registry.db                  # 项目注册表
+├── indexes/                     # 集中式索引存储
+└── venv/                        # Python 虚拟环境
+
+project/
+├── .codexlens/                  # 工作区本地目录
+│   ├── .env                     # 工作区 API 配置 (覆盖全局)
+│   ├── index.db                 # 项目索引数据库
+│   ├── cache/                   # 缓存目录
+│   └── .gitignore               # 排除敏感文件
+└── .env                         # 项目根目录配置
+```
+
+## 配置优先级
+
+配置加载顺序 (后者覆盖前者):
+
+| 优先级 | 位置 | 说明 |
+|--------|------|------|
+| 1 (最低) | `~/.codexlens/.env` | 全局默认配置 |
+| 2 | `project/.env` | 项目根目录配置 |
+| 3 | `project/.codexlens/.env` | 工作区本地配置 |
+| 4 (最高) | 环境变量 | Shell 环境变量 |
+
+## 环境变量
+
+### Embedding 配置
+
+用于 `litellm` 后端的嵌入向量服务:
+
+```bash
+# API 密钥
+EMBEDDING_API_KEY=your-api-key
+
+# API 基础 URL
+EMBEDDING_API_BASE=https://api.example.com/v1
+
+# 嵌入模型名称
+EMBEDDING_MODEL=text-embedding-3-small
+```
+
+**支持的提供商示例**:
+
+| 提供商 | API Base | 模型示例 |
+|--------|----------|----------|
+| OpenAI | `https://api.openai.com/v1` | `text-embedding-3-small` |
+| ModelScope | `https://api-inference.modelscope.cn/v1` | `Qwen/Qwen3-Embedding-8B` |
+| Azure | `https://your-resource.openai.azure.com` | `text-embedding-ada-002` |
+
+### LiteLLM 配置
+
+用于 LLM 功能 (重排序、语义分析等):
+
+```bash
+# API 密钥
+LITELLM_API_KEY=your-api-key
+
+# API 基础 URL
+LITELLM_API_BASE=https://api.example.com/v1
+
+# 模型名称
+LITELLM_MODEL=gpt-4o-mini
+```
+
+### Reranker 配置
+
+用于搜索结果重排序 (可选):
+
+```bash
+# API 密钥
+RERANKER_API_KEY=your-api-key
+
+# API 基础 URL
+RERANKER_API_BASE=https://api.siliconflow.cn
+
+# 提供商: siliconflow, cohere, jina
+RERANKER_PROVIDER=siliconflow
+
+# 重排序模型
+RERANKER_MODEL=BAAI/bge-reranker-v2-m3
+```
+
+### 通用配置
+
+```bash
+# 自定义数据目录 (默认: ~/.codexlens)
+CODEXLENS_DATA_DIR=~/.codexlens
+
+# 启用调试模式
+CODEXLENS_DEBUG=false
+```
+
+## settings.json
+
+运行时设置保存在 `~/.codexlens/settings.json`:
+
+```json
+{
+  "embedding": {
+    "backend": "litellm",
+    "model": "Qwen/Qwen3-Embedding-8B",
+    "use_gpu": false,
+    "endpoints": [
+      {
+        "model": "Qwen/Qwen3-Embedding-8B",
+        "api_key": "${EMBEDDING_API_KEY}",
+        "api_base": "${EMBEDDING_API_BASE}",
+        "weight": 1.0
+      }
+    ],
+    "strategy": "latency_aware",
+    "cooldown": 60.0
+  },
+  "llm": {
+    "enabled": true,
+    "tool": "gemini",
+    "timeout_ms": 300000,
+    "batch_size": 5
+  }
+}
+```
+
+### Embedding 设置
+
+| 字段 | 类型 | 说明 |
+|------|------|------|
+| `backend` | string | `fastembed` (本地) 或 `litellm` (API) |
+| `model` | string | 模型名称或配置文件 |
+| `use_gpu` | bool | GPU 加速 (仅 fastembed) |
+| `endpoints` | array | 多端点配置 (仅 litellm) |
+| `strategy` | string | 负载均衡策略 |
+| `cooldown` | float | 限流冷却时间 (秒) |
+
+**Embedding Backend 对比**:
+
+| 特性 | fastembed | litellm |
+|------|-----------|---------|
+| 运行方式 | 本地 ONNX | API 调用 |
+| 依赖 | 本地模型文件 | API 密钥 |
+| 速度 | 快 (本地) | 取决于网络 |
+| 模型选择 | 预定义配置文件 | 任意 API 模型 |
+| GPU 支持 | 是 | N/A |
+
+**负载均衡策略**:
+
+| 策略 | 说明 |
+|------|------|
+| `round_robin` | 轮询分配 |
+| `latency_aware` | 延迟感知 (推荐) |
+| `weighted_random` | 加权随机 |
+
+### LLM 设置
+
+| 字段 | 类型 | 说明 |
+|------|------|------|
+| `enabled` | bool | 启用 LLM 功能 |
+| `tool` | string | LLM 工具 (`gemini`, `codex`) |
+| `timeout_ms` | int | 超时时间 (毫秒) |
+| `batch_size` | int | 批处理大小 |
+
+## FastEmbed 模型配置文件
+
+使用 `fastembed` 后端时的预定义模型:
+
+| 配置文件 | 模型 | 维度 | 大小 |
+|----------|------|------|------|
+| `fast` | BAAI/bge-small-en-v1.5 | 384 | 80MB |
+| `base` | BAAI/bge-base-en-v1.5 | 768 | 220MB |
+| `code` | jinaai/jina-embeddings-v2-base-code | 768 | 150MB |
+| `minilm` | sentence-transformers/all-MiniLM-L6-v2 | 384 | 90MB |
+| `multilingual` | intfloat/multilingual-e5-large | 1024 | 1000MB |
+| `balanced` | mixedbread-ai/mxbai-embed-large-v1 | 1024 | 600MB |
+
+## 快速开始
+
+### 1. 使用全局配置
+
+创建 `~/.codexlens/.env`:
+
+```bash
+# 复制示例配置
+cp codex-lens/.env.example ~/.codexlens/.env
+
+# 编辑配置
+nano ~/.codexlens/.env
+```
+
+### 2. 使用本地嵌入 (fastembed)
+
+```bash
+# 初始化索引 (使用 code 配置文件)
+codexlens init --backend fastembed --model code
+
+# 或使用多语言模型
+codexlens init --backend fastembed --model multilingual
+```
+
+### 3. 使用 API 嵌入 (litellm)
+
+```bash
+# 设置环境变量
+export EMBEDDING_API_KEY=your-key
+export EMBEDDING_API_BASE=https://api.example.com/v1
+export EMBEDDING_MODEL=text-embedding-3-small
+
+# 初始化索引
+codexlens init --backend litellm --model text-embedding-3-small
+```
+
+### 4. 验证配置
+
+```bash
+# 检查配置加载
+codexlens config show
+
+# 测试嵌入
+codexlens test-embedding "Hello World"
+```
+
+## 故障排除
+
+### 配置未加载
+
+检查文件权限和路径:
+
+```bash
+ls -la ~/.codexlens/.env
+cat ~/.codexlens/.env
+```
+
+### API 错误
+
+1. 验证 API 密钥有效性
+2. 检查 API Base URL 是否正确
+3. 确认模型名称匹配提供商支持的模型
+
+### 模型不兼容
+
+如果更换嵌入模型，需要重建索引:
+
+```bash
+# 删除旧索引
+rm -rf project/.codexlens/
+
+# 重新初始化
+codexlens init --backend litellm --model new-model
+```
+
+## 相关文件
+
+| 文件 | 说明 |
+|------|------|
+| `src/codexlens/config.py` | 配置类定义 |
+| `src/codexlens/env_config.py` | 环境变量加载 |
+| `src/codexlens/cli/model_manager.py` | FastEmbed 模型管理 |
+| `src/codexlens/semantic/factory.py` | Embedder 工厂 |
diff --git a/codex-lens/src/codexlens/cli/commands.py b/codex-lens/src/codexlens/cli/commands.py
index d0cf3b5a..8f3660a9 100644
--- a/codex-lens/src/codexlens/cli/commands.py
+++ b/codex-lens/src/codexlens/cli/commands.py
@@ -527,8 +527,8 @@ def search(
                 console.print("[dim]Use --method with: fts, vector, splade, hybrid, cascade[/dim]")
             raise typer.Exit(code=1)
 
-    # Configure search
-    config = Config()
+    # Configure search (load settings from file)
+    config = Config.load()
 
     # Validate method
     valid_methods = ["fts", "vector", "splade", "hybrid", "cascade"]
diff --git a/codex-lens/src/codexlens/config.py b/codex-lens/src/codexlens/config.py
index fd65418a..a56aab67 100644
--- a/codex-lens/src/codexlens/config.py
+++ b/codex-lens/src/codexlens/config.py
@@ -265,6 +265,12 @@ class Config:
                 "timeout_ms": self.llm_timeout_ms,
                 "batch_size": self.llm_batch_size,
             },
+            "reranker": {
+                "enabled": self.enable_cross_encoder_rerank,
+                "backend": self.reranker_backend,
+                "model": self.reranker_model,
+                "top_k": self.reranker_top_k,
+            },
         }
         with open(self.settings_path, "w", encoding="utf-8") as f:
             json.dump(settings, f, indent=2)
@@ -313,6 +319,25 @@ class Config:
                 self.llm_timeout_ms = llm["timeout_ms"]
             if "batch_size" in llm:
                 self.llm_batch_size = llm["batch_size"]
+
+            # Load reranker settings
+            reranker = settings.get("reranker", {})
+            if "enabled" in reranker:
+                self.enable_cross_encoder_rerank = reranker["enabled"]
+            if "backend" in reranker:
+                backend = reranker["backend"]
+                if backend in {"onnx", "api", "litellm", "legacy"}:
+                    self.reranker_backend = backend
+                else:
+                    log.warning(
+                        "Invalid reranker backend in %s: %r (expected 'onnx', 'api', 'litellm', or 'legacy')",
+                        self.settings_path,
+                        backend,
+                    )
+            if "model" in reranker:
+                self.reranker_model = reranker["model"]
+            if "top_k" in reranker:
+                self.reranker_top_k = reranker["top_k"]
         except Exception as exc:
             log.warning(
                 "Failed to load settings from %s (%s): %s",
diff --git a/codex-lens/src/codexlens/env_config.py b/codex-lens/src/codexlens/env_config.py
index bb6061c6..156378f5 100644
--- a/codex-lens/src/codexlens/env_config.py
+++ b/codex-lens/src/codexlens/env_config.py
@@ -95,39 +95,68 @@ def load_env_file(env_path: Path) -> Dict[str, str]:
     return env_vars
 
 
+def _get_global_data_dir() -> Path:
+    """Get global CodexLens data directory."""
+    env_override = os.environ.get("CODEXLENS_DATA_DIR")
+    if env_override:
+        return Path(env_override).expanduser().resolve()
+    return (Path.home() / ".codexlens").resolve()
+
+
+def load_global_env() -> Dict[str, str]:
+    """Load environment variables from global ~/.codexlens/.env file.
+
+    Returns:
+        Dictionary of environment variables from global config
+    """
+    global_env_path = _get_global_data_dir() / ".env"
+    if global_env_path.is_file():
+        env_vars = load_env_file(global_env_path)
+        log.debug("Loaded %d vars from global %s", len(env_vars), global_env_path)
+        return env_vars
+    return {}
+
+
 def load_workspace_env(workspace_root: Path | None = None) -> Dict[str, str]:
     """Load environment variables from workspace .env files.
-    
+
     Priority (later overrides earlier):
-    1. Project root .env
-    2. .codexlens/.env
-    
+    1. Global ~/.codexlens/.env (lowest priority)
+    2. Project root .env
+    3. .codexlens/.env (highest priority)
+
     Args:
         workspace_root: Workspace root directory. If None, uses current directory.
-        
+
     Returns:
         Merged dictionary of environment variables
     """
     if workspace_root is None:
         workspace_root = Path.cwd()
-    
+
     workspace_root = Path(workspace_root).resolve()
-    
+
     env_vars: Dict[str, str] = {}
-    
-    # Load from project root .env (lowest priority)
+
+    # Load from global ~/.codexlens/.env (lowest priority)
+    global_vars = load_global_env()
+    if global_vars:
+        env_vars.update(global_vars)
+
+    # Load from project root .env (medium priority)
     root_env = workspace_root / ".env"
     if root_env.is_file():
-        env_vars.update(load_env_file(root_env))
-        log.debug("Loaded %d vars from %s", len(env_vars), root_env)
-    
-    # Load from .codexlens/.env (higher priority)
+        loaded = load_env_file(root_env)
+        env_vars.update(loaded)
+        log.debug("Loaded %d vars from %s", len(loaded), root_env)
+
+    # Load from .codexlens/.env (highest priority)
     codexlens_env = workspace_root / ".codexlens" / ".env"
     if codexlens_env.is_file():
         loaded = load_env_file(codexlens_env)
         env_vars.update(loaded)
         log.debug("Loaded %d vars from %s", len(loaded), codexlens_env)
-    
+
     return env_vars
 
 
diff --git a/compare_reranker.py b/compare_reranker.py
new file mode 100644
index 00000000..054d576b
--- /dev/null
+++ b/compare_reranker.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python
+"""Compare search results with and without reranker."""
+import json
+import subprocess
+import sys
+import os
+
+os.chdir(r"D:\dongdiankaifa9\hydro_generator_module")
+
+query = "热网络计算"
+
+def run_search(method: str) -> dict:
+    """Run search and return parsed JSON result."""
+    cmd = [sys.executable, "-m", "codexlens", "search", query, "--method", method, "--limit", "10", "--json"]
+    result = subprocess.run(cmd, capture_output=True, text=True, encoding="utf-8")
+    # Find JSON in output (skip debug lines)
+    for line in result.stdout.split("\n"):
+        if line.strip().startswith("{"):
+            try:
+                return json.loads(line)
+            except:
+                pass
+    # Try to find JSON object in stderr
+    output = result.stdout + result.stderr
+    start = output.find('{"success"')
+    if start >= 0:
+        # Find matching closing brace
+        depth = 0
+        for i, c in enumerate(output[start:]):
+            if c == '{':
+                depth += 1
+            elif c == '}':
+                depth -= 1
+                if depth == 0:
+                    try:
+                        return json.loads(output[start:start+i+1])
+                    except:
+                        pass
+                    break
+    return {"success": False, "error": "Failed to parse JSON"}
+
+print("=" * 60)
+print("搜索对比: 有无 Reranker 效果")
+print("查询:", query)
+print("=" * 60)
+
+# Run hybrid search (no reranker)
+print("\n[1] Hybrid 搜索 (无 Reranker)")
+print("-" * 40)
+hybrid_result = run_search("hybrid")
+if hybrid_result.get("success"):
+    results = hybrid_result.get("result", {}).get("results", [])[:10]
+    for i, r in enumerate(results, 1):
+        path = r.get("path", "").split("\\")[-1]
+        score = r.get("score", 0)
+        print(f"{i:2}. {path[:45]:<45} score={score:.4f}")
+else:
+    print("搜索失败:", hybrid_result.get("error"))
+
+# Run cascade search (with reranker)
+print("\n[2] Cascade 搜索 (使用 Reranker)")
+print("-" * 40)
+cascade_result = run_search("cascade")
+if cascade_result.get("success"):
+    results = cascade_result.get("result", {}).get("results", [])[:10]
+    for i, r in enumerate(results, 1):
+        path = r.get("path", "").split("\\")[-1]
+        score = r.get("score", 0)
+        print(f"{i:2}. {path[:45]:<45} score={score:.4f}")
+else:
+    print("搜索失败:", cascade_result.get("error"))
+
+print("\n" + "=" * 60)
+print("对比说明:")
+print("- Hybrid: FTS + Vector 融合，无二次重排序")
+print("- Cascade: Vector 粗筛 + Reranker API 精排")
+print("=" * 60)