> For the complete documentation index, see [llms.txt](https://docs.algenta.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.algenta.ai/engine-runtime/runtime-libraries.md).

# Runtime libraries

The runtime library surface — list, health-check, and execute individual runtime-backed functions over HTTP, the de CLI, or MCP. Off by default; an operator enables the HTTP routes.

Beyond the high-level engines, Algenta can expose its individual **runtime libraries** — the compiled functions that the engines are built from — so you can call one directly. This is the low-level compute surface: you name a `module` and a `function`, pass JSON args, and get the result plus its latency. It is distinct from the governed data and query APIs; nothing here touches a dataset. For the complete list of modules grouped by domain (vision, LLM, ML, statistics, signal, crypto, and more), see the [Runtime library catalog](/engine-runtime/runtime-library-catalog.md).

The supported public surface is the authenticated HTTP API below. It executes inside the selected Algenta deployment and returns the same structured contract as other `/v1` operations.

{% hint style="warning" %}
The authenticated HTTP routes (`/v1/libraries*`) are enabled by default so SDK and MCP clients can discover them without operator setup. A self-host operator can set `ALGENTA_RUNTIME_LIBRARY_HTTP_API_ENABLED=false` to remove the routes; disabled routes return `404`. See the [configuration reference](/deploy-and-operate/configuration.md).
{% endhint %}

## HTTP surface

Every route requires a bearer API key and a verified account, and is rate-limited per plan. Base URL is `https://api.algenta.ai` or your own origin such as `http://localhost:8000`.

| Method + path                | Purpose                                                                  |
| ---------------------------- | ------------------------------------------------------------------------ |
| `GET /v1/libraries`          | List executable runtime libraries (paginated, filterable).               |
| `GET /v1/libraries/health`   | Report whether the runtime is available and how many modules it exposes. |
| `POST /v1/libraries/execute` | Execute one function by `module` + `function`.                           |

### List libraries

`GET /v1/libraries` returns the modules the runtime exposes, each with its exported functions.

| Query param | Default | Meaning                                                         |
| ----------- | ------- | --------------------------------------------------------------- |
| `page`      | `1`     | Page number.                                                    |
| `limit`     | `50`    | Page size (max `200`).                                          |
| `q`         | —       | Substring filter over module names and exported function names. |

{% code title="List and filter libraries" %}

```bash
curl -sS "$ALGENTA_BASE_URL/v1/libraries?q=ab_testing&limit=50" \
  -H "Authorization: Bearer $ALGENTA_API_KEY"
```

{% endcode %}

```json
{
  "modules": [
    {
      "name": "ab_testing",
      "engine": "mojo",
      "functions": ["confidence_interval", "sample_size", "significance"]
    }
  ],
  "count": 1,
  "total": 1,
  "page": 1,
  "limit": 50,
  "pages": 1
}
```

Each module carries a `name`, the `engine` that backs it (`mojo` when the runtime is live, `unavailable` otherwise), and its sorted `functions`.

### Check availability

`GET /v1/libraries/health` tells you whether the runtime is executing before you attempt a call.

{% code title="Runtime library health" %}

```bash
curl -sS "$ALGENTA_BASE_URL/v1/libraries/health" \
  -H "Authorization: Bearer $ALGENTA_API_KEY"
```

{% endcode %}

```json
{
  "status": "ok",
  "engine": "mojo",
  "module_count": 42,
  "runtime_available": true
}
```

If the bundled runtime is unhealthy, the response has `status: "unavailable"`, `engine: "unavailable"`, and `runtime_available: false`. This is a deployment health failure, not a prompt to start another service; verify or redeploy Algenta.

### Execute a function

`POST /v1/libraries/execute` runs a single function.

| Body field   | Required | Meaning                                                                    |
| ------------ | -------- | -------------------------------------------------------------------------- |
| `module`     | yes      | Runtime module name, e.g. `ab_testing` (dotted names are allowed).         |
| `function`   | yes      | An exported function name from that module.                                |
| `args`       | no       | JSON args: an object (kwargs), an array (positional), a scalar, or `null`. |
| `request_id` | no       | Caller-supplied idempotency or tracing identifier.                         |

{% code title="Execute one function" %}

```bash
curl -sS -X POST "$ALGENTA_BASE_URL/v1/libraries/execute" \
  -H "Authorization: Bearer $ALGENTA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "module": "ab_testing",
    "function": "sample_size",
    "args": { "baseline_rate": 0.1, "mde": 0.02, "power": 0.8 }
  }'
```

{% endcode %}

```json
{
  "module": "ab_testing",
  "function": "sample_size",
  "result": { "per_variant": 3843, "total": 7686 },
  "latency_ms": 4.12,
  "engine_used": "mojo",
  "request_id": "req_..."
}
```

The response echoes the `module` and `function`, returns the `result`, and reports `latency_ms` and the `engine_used`. If you sent a `request_id`, it comes back on the response; otherwise the engine's own request id is used.

### Execute errors

Execution failures use the standard error envelope, with the HTTP status mapped from the failure `code`.

| Status | `code`                        | Meaning                                                                      |
| ------ | ----------------------------- | ---------------------------------------------------------------------------- |
| 404    | `module_not_registered`       | No such module. Check `GET /v1/libraries`.                                   |
| 404    | `function_not_registered`     | The module has no such function.                                             |
| 422    | `invalid_arguments`           | The `args` shape did not match the function signature.                       |
| 503    | `compute_runtime_unavailable` | The bundled runtime is unhealthy or missing; verify the deployment artifact. |
| 504    | `mojo_library_timeout`        | The function ran past its time budget.                                       |
| 502    | (other)                       | Unexpected runtime error.                                                    |

```json
{
  "error": {
    "code": "function_not_registered",
    "message": "Function 'sampl_size' is not registered for module 'ab_testing'.",
    "details": {},
    "request_id": "req_..."
  }
}
```

## Related references

* [Configuration reference](/deploy-and-operate/configuration.md) — the toggle that exposes the HTTP routes.
* [Verify the bundled engine](/engine-runtime/bundled-runtime.md) — confirm the integrated runtime is healthy.
* [Engine catalog](/engine-runtime/catalog.md) — the higher-level engines these libraries compose into.
* [MCP server](/sdks/mcp.md) — connect an MCP host to this instance.


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