> ## Documentation Index
> Fetch the complete documentation index at: https://docs.veadk.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Use Context Search storage

The `context_search` backend integrates with the managed Volcengine Context Search service. Files are uploaded to TOS (object storage) via pre-signed URLs, then registered into a Context Search RAG scene; splitting, embedding, and retrieval all run server-side, so **no local embedding is required**.

## When to use

* You need a managed semantic-search service without maintaining a vector store yourself;
* You have created a RAG scene and a search engine in Volcengine Context Search.

## Prerequisites

* A Volcengine account with a Context Search RAG scene whose scene ID is a numeric string;
* The search engine's Endpoint and API Key (required for retrieval).

## Usage

```python lines theme={null}
from veadk import Agent
from veadk.knowledgebase import KnowledgeBase

# index is the Context Search scene ID (Scene Id), a numeric string
kb = KnowledgeBase(backend="context_search", index="123456789")
kb.add_from_text("The standard annual leave is 15 days per year, available after one year of service.")

agent = Agent(
    name="demo",
    instruction="Answer the user; when needed, use the `load_knowledgebase` tool to search the knowledge base.",
    knowledgebase=kb,
)
```

You can also pass credentials and engine info explicitly via `backend_config`:

```python lines theme={null}
from veadk.knowledgebase import KnowledgeBase

kb = KnowledgeBase(
    backend="context_search",
    index="123456789",
    backend_config={
        "index": "123456789",
        "volcengine_access_key": "your-ak",
        "volcengine_secret_key": "your-sk",
        "context_search_project": "default",
        "context_search_engine_endpoint": "https://your-engine-endpoint",
        "context_search_engine_apikey": "your-engine-apikey",
    },
)
```

## Parameters

### Constructor parameters

`backend_config` supports the following settings:

| Parameter | Type | Default | Description |
| :- | :- | :- | :- |
| `index` | `str` | No default; provided by `KnowledgeBase` | Scene ID (Scene Id), a numeric string; used as the scene ID when `context_search_engine_id` is empty. |
| `volcengine_access_key` | `str \| None` | Read from env var `VOLCENGINE_ACCESS_KEY` | Volcengine access key (AK). |
| `volcengine_secret_key` | `str \| None` | Read from env var `VOLCENGINE_SECRET_KEY` | Volcengine secret key (SK). |
| `volcengine_session_token` | `str \| None` | Read from env var `VOLCENGINE_SESSION_TOKEN` | STS temporary-credential token. |
| `context_search_region` | `str \| None` | Read from env var `DATABASE_CONTEXT_SEARCH_REGION`; defaults to `cn-beijing` (`ap-southeast-1` under `byteplus`) | Service region. |
| `context_search_project` | `str \| None` | Read from env var `DATABASE_CONTEXT_SEARCH_PROJECT`; defaults to `default` | Context Search project name. |
| `context_search_engine_id` | `str \| None` | Read from env var `DATABASE_CONTEXT_SEARCH_ENGINE_ID` | Search engine ID; when set, takes precedence as the scene ID. |
| `context_search_engine_endpoint` | `str \| None` | Read from env var `DATABASE_CONTEXT_SEARCH_ENGINE_ENDPOINT` | Search engine endpoint, required for retrieval. |
| `context_search_engine_apikey` | `str \| None` | Read from env var `DATABASE_CONTEXT_SEARCH_ENGINE_APIKEY` | Search engine API key, required for retrieval. |
| `context_search_service` | `str` | `ctxsearch` | Service identifier. |
| `context_search_version` | `str` | `2025-09-01` | API version. |
| `context_search_host` | `str` | `ctxsearch.volcengineapi.com` | API host. Replaced with `byteplusapi.com` under `byteplus`. |
| `context_search_scheme` | `str` | `https` | Request scheme. |

## Environment variables

```bash lines theme={null}
# Volcengine credentials
export VOLCENGINE_ACCESS_KEY="your-ak"
export VOLCENGINE_SECRET_KEY="your-sk"

# Context Search
export DATABASE_CONTEXT_SEARCH_PROJECT="default"
export DATABASE_CONTEXT_SEARCH_REGION="cn-beijing"
export DATABASE_CONTEXT_SEARCH_ENGINE_ID="your-engine-id"
export DATABASE_CONTEXT_SEARCH_ENGINE_ENDPOINT="https://your-engine-endpoint"
export DATABASE_CONTEXT_SEARCH_ENGINE_APIKEY="your-engine-apikey"
```

<Note>
  Embedding and retrieval both run server-side in Context Search, so this backend requires no embedding model configuration. Ingestion is asynchronous: after files are uploaded, wait for server-side indexing to complete before searching.
</Note>

<Warning>
  `index` (the scene ID) must be a numeric string, otherwise initialization fails; initialization also calls `GetScene` to verify the scene exists. Before retrieval, `context_search_engine_endpoint` and `context_search_engine_apikey` must be set, otherwise `search` fails.
</Warning>