docs(config): update rerank configuration and add threshold range (#1138)

- Correct the rerank provider list (from 'volcengine' to 'vikingdb')
- Update authentication fields (from 'api_key' to 'ak'/'sk' for vikingdb)
- Add 'cohere', 'openai', and 'litellm' as supported rerank providers
- Include numeric range (0.0 to 1.0) for the threshold parameter
- Add Pydantic range validation for the threshold field in rerank_config.py

Author: ousugo

docs/en/guides/01-configuration.md

@@ -8,28 +8,32 @@ Create `~/.openviking/ov.conf` in your project directory:
 
 ```json
 {
+  "storage": {
+    "workspace": "./data",
+    "vectordb": {
+      "name": "context",
+      "backend": "local"
+    },
+    "agfs": {
+      "port": 1833,
+      "log_level": "warn",
+      "backend": "local"
+    }
+  },
   "embedding": {
     "dense": {
-      "provider": "volcengine",
-      "api_key": "your-api-key",
-      "model": "doubao-embedding-vision-250615",
-      "dimension": 1024
+      "api_base" : "<api-endpoint>",
+      "api_key"  : "<your-api-key>",
+      "provider" : "<provider-type>",
+      "dimension": 1024,
+      "model"    : "<model-name>"
     }
   },
   "vlm": {
-    "provider": "volcengine",
-    "api_key": "your-api-key",
-    "model": "doubao-seed-2-0-pro-260215"
-  },
-  "rerank": {
-    "provider": "volcengine",
-    "api_key": "your-api-key",
-    "model": "doubao-rerank-250615"
-  },
-  "storage": {
-    "workspace": "./data",
-    "agfs": { "backend": "local" },
-    "vectordb": { "backend": "local" }
+    "api_base" : "<api-endpoint>",
+    "api_key"  : "<your-api-key>",
+    "provider" : "<provider-type>",
+    "model"    : "<model-name>"
   }
 }
 ```
@@ -500,39 +504,54 @@ See [Code Skeleton Extraction](../concepts/06-extraction.md#code-skeleton-extrac
 
 ### rerank
 
-Reranking model for search result refinement.
+Reranking model for search result refinement. Supports VikingDB (Volcengine), Cohere, OpenAI-compatible APIs, and LiteLLM.
+
+**Volcengine (VikingDB):**
 
 ```json
 {
   "rerank": {
-    "provider": "volcengine",
-    "api_key": "your-api-key",
-    "model": "doubao-rerank-250615"
+    "provider": "vikingdb",
+    "ak": "your-access-key",
+    "sk": "your-secret-key",
+    "model_name": "doubao-seed-rerank",
+    "model_version": "251028"
   }
 }
 ```
 
-**OpenAI-compatible provider (e.g. DashScope qwen3-rerank):**
+**OpenAI-compatible provider (e.g. DashScope):**
 
 ```json
 {
   "rerank": {
     "provider": "openai",
     "api_key": "your-api-key",
     "api_base": "https://dashscope.aliyuncs.com/compatible-api/v1/reranks",
-    "model": "qwen3-rerank",
+    "model": "qwen3-vl-rerank",
     "threshold": 0.1
   }
 }
 ```
 
+**Parameters**
+
 | Parameter | Type | Description |
 |-----------|------|-------------|
-| `provider` | str | `"volcengine"` or `"openai"` |
-| `api_key` | str | API key |
-| `model` | str | Model name |
-| `api_base` | str | Endpoint URL (openai provider only) |
-| `threshold` | float | Score threshold; results below this are filtered out. Default: `0.1` |
+| `provider` | str | `"vikingdb"`, `"cohere"`, `"openai"`, or `"litellm"`. Auto-detected if omitted. |
+| `ak` | str | VikingDB Access Key (vikingdb provider only) |
+| `sk` | str | VikingDB Secret Key (vikingdb provider only) |
+| `model_name` | str | Model name (vikingdb provider only, default: `doubao-seed-rerank`) |
+| `api_key` | str | API key (for `openai`, `cohere`, or `litellm` providers) |
+| `api_base` | str | Endpoint URL (for `openai` provider) |
+| `model` | str | Model name (for `openai` or `litellm` providers) |
+| `threshold` | float | Score threshold between `0.0` and `1.0`; results below this are filtered out. Default: `0.1` |
+
+**Supported providers:**
+- `vikingdb`: Volcengine VikingDB Rerank API (uses AK/SK)
+- `cohere`: Cohere Rerank API
+- `openai`: OpenAI-compatible Rerank API
+- `litellm`: Rerank services via LiteLLM (requires `litellm` package)
 
 If rerank is not configured, search uses vector similarity only.
 

docs/zh/guides/01-configuration.md

@@ -475,39 +475,54 @@ AST 提取支持：Python、JavaScript/TypeScript、Rust、Go、Java、C/C++。
 
 ### rerank
 
-用于搜索结果精排的 Rerank 模型。
+用于搜索结果精排的 Rerank 模型。支持 VikingDB (火山引擎)、Cohere、OpenAI 兼容接口和 LiteLLM。
+
+**火山引擎 (VikingDB):**
 
 ```json
 {
   "rerank": {
-    "provider": "volcengine",
-    "api_key": "your-api-key",
-    "model": "doubao-rerank-250615"
+    "provider": "vikingdb",
+    "ak": "your-access-key",
+    "sk": "your-secret-key",
+    "model_name": "doubao-seed-rerank",
+    "model_version": "251028"
   }
 }
 ```
 
-**OpenAI 兼容提供方（如 DashScope qwen3-rerank）：**
+**OpenAI 兼容提供方 (如 DashScope):**
 
 ```json
 {
   "rerank": {
     "provider": "openai",
     "api_key": "your-api-key",
     "api_base": "https://dashscope.aliyuncs.com/compatible-api/v1/reranks",
-    "model": "qwen3-rerank",
+    "model": "qwen3-vl-rerank",
     "threshold": 0.1
   }
 }
 ```
 
+**参数**
+
 | 参数 | 类型 | 说明 |
 |------|------|------|
-| `provider` | str | `"volcengine"` 或 `"openai"` |
-| `api_key` | str | API Key |
-| `model` | str | 模型名称 |
-| `api_base` | str | 接口地址（openai 提供方专用） |
-| `threshold` | float | 分数阈值，低于此值的结果会被过滤。默认：`0.1` |
+| `provider` | str | `"vikingdb"`、`"cohere"`、`"openai"` 或 `"litellm"`。省略时基于字段自动识别。 |
+| `ak` | str | VikingDB Access Key（仅 `vikingdb` 提供方使用） |
+| `sk` | str | VikingDB Secret Key（仅 `vikingdb` 提供方使用） |
+| `model_name` | str | 模型名称（仅 `vikingdb` 提供方使用，默认：`doubao-seed-rerank`） |
+| `api_key` | str | API Key（用于 `openai`、`cohere` 或 `litellm` 提供方） |
+| `api_base` | str | 接口地址（用于 `openai` 提供方） |
+| `model` | str | 模型名称（用于 `openai` 或 `litellm` 提供方） |
+| `threshold` | float | 分数阈值，范围为 `0.0` 到 `1.0`。低于此值的结果会被过滤。默认：`0.1` |
+
+**支持的提供方:**
+- `vikingdb`: 火山引擎 VikingDB Rerank API (使用 AK/SK)
+- `cohere`: Cohere Rerank API
+- `openai`: OpenAI 兼容的 Rerank 接口
+- `litellm`: 通过 LiteLLM 调用的 Rerank 服务 (需安装 `litellm`)
 
 如果未配置 Rerank，搜索仅使用向量相似度。