# Lemonade API

We have designed a set of Lemonade-specific endpoints to enable client applications by extending the existing cloud-focused APIs (e.g., OpenAI). These extensions allow for a greater degree of UI/UX responsiveness in native applications by allowing applications to:

- Download models at setup time.
- Pre-load models at UI-loading-time, as opposed to completion-request time.
- Unload models to save memory space.
- Understand system resources and state to make dynamic choices.

| Method | Endpoint | Description |
|--------|----------|-------------|
| `POST` | [`/v1/pull`](#post-v1pull) | Install a model |
| `GET` | [`/v1/downloads`](#get-v1downloads) | List server-owned model download jobs |
| `POST` | [`/v1/downloads/control`](#post-v1downloadscontrol) | Pause, cancel, or remove server-owned model download jobs |
| `GET` | [`/v1/pull/variants`](#get-v1pullvariants) | Enumerate GGUF variants for a Hugging Face checkpoint |
| `POST` | [`/v1/delete`](#post-v1delete) | Delete a model |
| `POST` | [`/v1/load`](#post-v1load) | Load a model |
| `POST` | [`/v1/unload`](#post-v1unload) | Unload a model |
| `POST` | [`/v1/audio/generations`](#post-v1audiogenerations) | Generate audio (music or sound effects) from a text prompt |
| `GET` | [`/v1/models/{id}/files`](#get-v1modelsidfiles) | List resolved local file metadata for one model |
| `GET` | [`/v1/health`](#get-v1health) | Check server status, such as models loaded |
| `GET` | [`/v1/stats`](#get-v1stats) | Performance statistics from the last request |
| `GET` | [`/v1/system-stats`](#get-v1system-stats) | Current host resource usage |
| `GET` | [`/v1/system-info`](#get-v1system-info) | System information and device enumeration |
| `POST` | [`/v1/install`](#post-v1install) | Install or update a backend, or register a cloud provider |
| `POST` | [`/v1/uninstall`](#post-v1uninstall) | Remove a backend or cloud provider |
| `POST` | [`/v1/cloud/auth`](#post-v1cloudauth) | Set an in-memory API key for a cloud provider |
| `DELETE` | [`/v1/cloud/auth/{provider}`](#delete-v1cloudauthprovider) | Clear the in-memory API key for a cloud provider |
| `WS` | [`/logs/stream`](#log-streaming-api-websocket) | Log Streaming |
| `GET` | [`/live`](#get-live) | Check server liveness for load balancers and orchestrators |
| `GET` | [`/metrics`](#get-metrics) | Prometheus metrics scrape endpoint |
| `POST` | [`/internal/telemetry/flush`](#post-internaltelemetryflush) | Force-flush all queued telemetry trace spans |

## `GET /v1/models/{id}/files`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

List resolved local file metadata for a single model. This endpoint is intended for model-detail UIs such as the Files tab. It is per-model inventory, not system or drive storage accounting.

The endpoint is available at:

- `/v1/models/{id}/files`
- `/api/v1/models/{id}/files`
- `/v0/models/{id}/files`
- `/api/v0/models/{id}/files`

By default, the response does not include absolute filesystem paths. Trusted local clients that need paths for native UI actions can request them explicitly with `?include_paths=true`. Absolute paths may reveal local usernames and cache layout, so clients should only request them when that disclosure is acceptable.

### Example request

```bash
curl http://localhost:13305/v1/models/Qwen3-4B/files
```

### Response format

```json
{
  "model_id": "Qwen3-4B",
  "files": [
    {
      "name": "model.gguf",
      "role": "main",
      "size_bytes": 123456789,
      "exists": true
    },
    {
      "name": "mmproj.gguf",
      "role": "mmproj",
      "size_bytes": 12345678,
      "exists": true
    }
  ]
}
```

### Optional path disclosure

```bash
curl 'http://localhost:13305/v1/models/Qwen3-4B/files?include_paths=true'
```

When `include_paths=true` is supplied, each file entry also includes `path`:

```json
{
  "name": "model.gguf",
  "path": "/abs/path/model.gguf",
  "role": "main",
  "size_bytes": 123456789,
  "exists": true
}
```

### Fields

| Field | Description |
|-------|-------------|
| `model_id` | Public model ID for the requested model. |
| `files` | Array of resolved model files known to the registry. |
| `files[].name` | Base filename from the resolved path. |
| `files[].path` | Absolute resolved path on the local system. Only included when `include_paths=true`; privacy-sensitive. |
| `files[].role` | Checkpoint role, for example `main`, `mmproj`, or another recipe-specific role. |
| `files[].size_bytes` | File size in bytes. Directories are summed recursively. Missing files report `0`. |
| `files[].exists` | Whether the resolved path currently exists on disk. |

## `POST /v1/pull`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Register and install models for use with Lemonade Server.

### Parameters

The Lemonade Server built-in model registry has a collection of model names that can be pulled and loaded. The `pull` endpoint can install any registered model, and it can also register-then-install any model available on Hugging Face.

**Common Parameters**

| Parameter | Required | Description |
|-----------|----------|-------------|
| `stream` | No | If `true`, returns Server-Sent Events (SSE) with download progress. Defaults to `false`. |
| `subscribe` | No | Only applies when `stream=true`. If `false`, the server starts a background model download job and returns a JSON snapshot immediately instead of keeping the HTTP response subscribed to SSE progress. Defaults to `true` for backwards compatibility. |

**Install a Model that is Already Registered**

| Parameter | Required | Description |
|-----------|----------|-------------|
| `model_name` | Yes | [Lemonade Server model name](https://lemonade-server.ai/models.html) to install. |

Example request:

```bash
curl -X POST http://localhost:13305/v1/pull \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "Qwen3-0.6B-GGUF"
  }'
```

Response format:

```json
{
  "status":"success",
  "message":"Installed model: Qwen3-0.6B-GGUF"
}
```

In case of an error, the status will be `error` and the message will contain the error message.

**Register and Install a Model**

Registration will place an entry for that model in the `user_models.json` file, which is located in the user's Lemonade cache (default: `~/.cache/lemonade`). Then, the model will be installed. Once the model is registered and installed, it will show up in the `models` endpoint alongside the built-in models and can be loaded.

The `recipe` field defines which software framework and device will be used to load and run the model.

> Note: the `model_name` for registering a new model must use the `user` namespace, to prevent collisions with built-in models. For example, `user.Phi-4-Mini-GGUF`.

| Parameter | Required | Description |
|-----------|----------|-------------|
| `model_name` | Yes | Namespaced [Lemonade Server model name](https://lemonade-server.ai/models.html) to register and install. |
| `checkpoint` | Yes | HuggingFace checkpoint to install. |
| `recipe` | Yes | Lemonade API recipe to load the model with. |
| `reasoning` | No | Whether the model is a reasoning model, like DeepSeek (default: false). Adds 'reasoning' label. |
| `vision` | No | Whether the model has vision capabilities for processing images (default: false). Adds 'vision' label. |
| `embedding` | No | Whether the model is an embedding model (default: false). Adds 'embeddings' label. |
| `reranking` | No | Whether the model is a reranking model (default: false). Adds 'reranking' label. |
| `mmproj` | No | Multimodal Projector (mmproj) file to use for vision models. |

Example request:

```bash
curl -X POST http://localhost:13305/v1/pull \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "user.Phi-4-Mini-GGUF",
    "checkpoint": "unsloth/Phi-4-mini-instruct-GGUF:Q4_K_M",
    "recipe": "llamacpp"
  }'
```

Response format:

```json
{
  "status":"success",
  "message":"Installed model: user.Phi-4-Mini-GGUF"
}
```

In case of an error, the status will be `error` and the message will contain the error message.

**Register an Omni-Model**

An omni collection is a collection type that bundles several models into a single entry that can be loaded, pulled, or deleted as a unit. Use `recipe: "collection.omni"` with a `components` array instead of `checkpoint`.

| Parameter | Required | Description |
|-----------|----------|-------------|
| `model_name` | Yes | Namespaced model name, e.g. `user.MyKit`. |
| `recipe` | Yes | Must be `"collection.omni"`. |
| `components` | Yes | Ordered, non-empty array of model names. Each component must be a regular model. |
| `models` | No | Ordered array of full model definitions, one per `components` entry (the same fields as single-model registration, keyed by `model_name`). When present, component names that are not yet registered are registered from these definitions; names that already exist keep their local definition. When absent, every `components` entry must already exist in the registry (built-in or a previously registered `user.*` model). |

Components do not need to be downloaded already — any not-yet-downloaded components are pulled by the same call. Deleting the collection removes only the collection entry; components stay on disk.

Example request:

```bash
curl -X POST http://localhost:13305/v1/pull \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "user.MyKit",
    "recipe": "collection.omni",
    "components": ["Qwen3-0.6B-GGUF", "Whisper-Tiny", "SD-Turbo"]
  }'
```

### Import an Exported Model File

Files written by `lemonade export` (and the desktop app's Export button) are import-ready
`/v1/pull` request bodies — POST the file contents verbatim to register and install the model.
This works for regular models and collections alike; exported collection files additionally
carry `components` plus a `models` array embedding each component's definition (see the
`models` parameter above). For the file format and the export/import/Hugging Face workflows,
see [Share a collection](../guide/configuration/custom-models.md#share-a-collection-export-import-and-hugging-face).

### Streaming Response (stream=true)

When `stream=true`, the endpoint returns Server-Sent Events with real-time download progress:

```
event: progress
data: {"file":"model.gguf","file_index":1,"total_files":2,"bytes_downloaded":1073741824,"bytes_total":2684354560,"percent":40}

event: progress
data: {"file":"config.json","file_index":2,"total_files":2,"bytes_downloaded":1024,"bytes_total":1024,"percent":100}

event: complete
data: {"file_index":2,"total_files":2,"percent":100}
```

**Event Types:**

| Event | Description |
|-------|-------------|
| `progress` | Sent during download with current file and byte progress |
| `complete` | Sent when all files are downloaded successfully |
| `error` | Sent if download fails, with `error` field containing the message |

### Server-owned download mode (`stream=true`, `subscribe=false`)

By default, `stream=true` keeps the `/v1/pull` HTTP response subscribed to Server-Sent Events until the download finishes. Clients that need download state to survive a renderer reload, tab close, or reconnect can also send `subscribe=false`.

When `stream=true` and `subscribe=false`, `/v1/pull` starts a server-owned model download job and returns a JSON snapshot immediately. The job continues on the server. Clients can poll [`GET /v1/downloads`](#get-v1downloads) to restore progress and can use [`POST /v1/downloads/control`](#post-v1downloadscontrol) to pause, cancel, or remove the job.

Example request:

```bash
curl -X POST http://localhost:13305/v1/pull \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "Qwen3-0.6B-GGUF",
    "stream": true,
    "subscribe": false
  }'
```

Example response:

```json
{
  "id": "model:Qwen3-0.6B-GGUF",
  "type": "model",
  "model_name": "Qwen3-0.6B-GGUF",
  "status": "downloading",
  "running": true,
  "file": "",
  "file_index": 0,
  "total_files": 0,
  "bytes_downloaded": 0,
  "bytes_total": 0,
  "total_download_size": 0,
  "bytes_previously_downloaded": 0,
  "completed_files_bytes": 0,
  "cumulative_bytes_downloaded": 0,
  "overall_bytes_downloaded": 0,
  "percent": 0,
  "complete": false
}
```

## `GET /v1/downloads`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

List server-owned model download jobs that were started with `POST /v1/pull` using `stream=true` and `subscribe=false`.

This endpoint is intended for clients that need to restore download-manager state after a reload or reconnect. Active, paused, cancelled, and errored jobs remain visible until the client removes them. Completed jobs remain visible briefly so clients can observe completion and refresh model state.

### Example request

```bash
curl http://localhost:13305/v1/downloads
```

### Response format

```json
[
  {
    "id": "model:Qwen3-0.6B-GGUF",
    "type": "model",
    "model_name": "Qwen3-0.6B-GGUF",
    "status": "downloading",
    "running": true,
    "file": "model.gguf",
    "file_index": 1,
    "total_files": 2,
    "bytes_downloaded": 1073741824,
    "bytes_total": 2684354560,
    "total_download_size": 2684355584,
    "bytes_previously_downloaded": 0,
    "completed_files_bytes": 0,
    "cumulative_bytes_downloaded": 1073741824,
    "overall_bytes_downloaded": 1073741824,
    "percent": 40,
    "complete": false
  }
]
```

### Download job fields

| Field | Description |
|-------|-------------|
| `id` | Stable download id. Model downloads use `model:<model_name>`. |
| `type` | Download type. Currently `model` for server-owned jobs. |
| `model_name` | Lemonade model name associated with the job. |
| `status` | Current state: `downloading`, `paused`, `cancelled`, `completed`, or `error`. |
| `running` | Whether the download worker is still active. A terminal-looking status may still have `running=true` while the worker is releasing resources. |
| `file`, `file_index`, `total_files` | Current file progress within the download. |
| `bytes_downloaded`, `bytes_total`, `percent` | Current-file byte progress as reported by the downloader. |
| `total_download_size` | Total expected bytes across all files when known. |
| `bytes_previously_downloaded` | Bytes already present on disk for the current file when resuming or skipping existing data. |
| `completed_files_bytes` | Bytes from files completed before the current file. |
| `cumulative_bytes_downloaded`, `overall_bytes_downloaded` | Total bytes downloaded across the whole job. `overall_bytes_downloaded` is kept as a compatibility alias. |
| `complete` | `true` when the download completed successfully. |
| `error` | Error message, present only for failed jobs. |

## `POST /v1/downloads/control`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Control a server-owned model download job.

### Parameters

| Parameter | Required | Description |
|-----------|----------|-------------|
| `id` | Yes | Download id returned by `POST /v1/pull` or `GET /v1/downloads`, for example `model:Qwen3-0.6B-GGUF`. |
| `action` | Yes | One of `pause`, `cancel`, or `remove`. |

### Actions

| Action | Description |
|--------|-------------|
| `pause` | Requests the worker to stop and keeps the job visible as `paused`. The worker may briefly report `running=true` while it unwinds. |
| `cancel` | Requests the worker to stop and marks the job as `cancelled`. Clients should wait for `running=false` before deleting partial files. |
| `remove` | Removes a stopped job from the server registry. If the worker is still running, the server keeps the job visible and treats the request as a cancel request until the worker stops. |

### Example request

```bash
curl -X POST http://localhost:13305/v1/downloads/control \
  -H "Content-Type: application/json" \
  -d '{
    "id": "model:Qwen3-0.6B-GGUF",
    "action": "pause"
  }'
```

### Response format

For `pause` and `cancel`, the endpoint returns the latest job snapshot:

```json
{
  "id": "model:Qwen3-0.6B-GGUF",
  "type": "model",
  "model_name": "Qwen3-0.6B-GGUF",
  "status": "paused",
  "running": false,
  "file": "model.gguf",
  "file_index": 1,
  "total_files": 2,
  "bytes_downloaded": 1073741824,
  "bytes_total": 2684354560,
  "percent": 40,
  "complete": false
}
```

For `remove`, the endpoint returns:

```json
{"status":"ok"}
```

If the job is already missing and `action` is `remove`, the endpoint returns:

```json
{"status":"ok","missing":true}
```

## `GET /v1/pull/variants`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Inspect a Hugging Face GGUF repository and enumerate the variants (quantizations and sharded folder groups) available for installation. Used by the `lemonade pull <owner/repo>` CLI flow and by the desktop app's model search to auto-populate the install form. The endpoint reads only public Hugging Face metadata; if the `HF_TOKEN` environment variable is set on the server, it is forwarded as a bearer token to access gated repositories.

### Parameters

| Parameter | Required | Description |
|-----------|----------|-------------|
| `checkpoint` | Yes | Hugging Face repo id, e.g. `unsloth/Qwen3-8B-GGUF`. Passed as a query string. |

Example request:

```bash
curl 'http://localhost:13305/v1/pull/variants?checkpoint=unsloth/Qwen3-8B-GGUF'
```

### Response

```json
{
  "checkpoint": "unsloth/Qwen3-8B-GGUF",
  "recipe": "llamacpp",
  "suggested_name": "Qwen3-8B-GGUF",
  "suggested_labels": ["vision"],
  "mmproj_files": ["mmproj-model-f16.gguf"],
  "variants": [
    {
      "name": "Q4_K_M",
      "primary_file": "Qwen3-8B-Q4_K_M.gguf",
      "files": ["Qwen3-8B-Q4_K_M.gguf"],
      "sharded": false,
      "size_bytes": 4920000000
    },
    {
      "name": "Q8_0",
      "primary_file": "Q8_0/Qwen3-8B-Q8_0-00001-of-00002.gguf",
      "files": ["Q8_0/Qwen3-8B-Q8_0-00001-of-00002.gguf", "Q8_0/Qwen3-8B-Q8_0-00002-of-00002.gguf"],
      "sharded": true,
      "size_bytes": 8500000000
    }
  ]
}
```

| Field | Description |
|-------|-------------|
| `checkpoint` | Echoed input. |
| `recipe` | Suggested recipe (always `llamacpp` today; future expansion may return other values). |
| `suggested_name` | Repo id stripped of the `owner/` prefix; suitable for use as the `user.<name>` model name. |
| `suggested_labels` | Inferred labels — `vision` if any `mmproj-*.gguf` files exist, plus `embeddings`/`reranking` if those substrings appear in the repo id. |
| `mmproj_files` | Bare filenames of `mmproj-*.gguf` files in the repo; the first one should be passed as `mmproj` to `/v1/pull` for vision models. |
| `variants[]` | Top quantizations for the repo, capped at 5. Each entry has `name` (e.g. `Q4_K_M`, `UD-Q4_K_XL`), `primary_file`, `files`, `sharded`, and `size_bytes` (from the HF `?blobs=true` listing). Ranked by frequency of use in `server_models.json` (`Q4_K_M`, `UD-Q4_K_XL`, `Q8_0`, `Q4_0` first, everything else sorted lexicographically). The CLI `lemonade pull` menu adds a free-text "Other" option for quants outside the top 5. |

### Error responses

| Status | Cause |
|--------|-------|
| 400 | `checkpoint` query parameter missing or malformed (must contain `/`). |
| 404 | Hugging Face returned 404 for the checkpoint. |
| 500 | Other transport or parsing failures; the response body contains an `error` message. |

## `POST /v1/delete`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Delete a model by removing it from local storage. If the model is currently loaded, it will be unloaded first.

> Note: deleting a collection (`recipe: "collection.omni"`) removes only the collection entry from `user_models.json`; its components stay on disk. Delete the components individually if you want to free their disk space.

### Parameters

| Parameter | Required | Description |
|-----------|----------|-------------|
| `model_name` | Yes | [Lemonade Server model name](https://lemonade-server.ai/models.html) to delete. |

Example request:

```bash
curl -X POST http://localhost:13305/v1/delete \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "Qwen3-0.6B-GGUF"
  }'
```

Response format:

```json
{
  "status":"success",
  "message":"Deleted model: Qwen3-0.6B-GGUF"
}
```

In case of an error, the status will be `error` and the message will contain the error message.

## `POST /v1/load`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Explicitly load a registered model into memory. This is useful to ensure that the model is loaded before you make a request. Installs the model if necessary.

> Note: loading a collection (`recipe: "collection.omni"`) loads each of its components in turn. Per-model options like `ctx_size` or `llamacpp_backend` are not forwarded to components — set them on each component's own `recipe_options.json` entry instead.

### Parameters

| Parameter | Required | Applies to | Description |
|-----------|----------|------------|-------------|
| `model_name` | Yes | All | [Lemonade Server model name](https://lemonade-server.ai/models.html) to load. |
| `pinned` | No | All | Boolean. If true, pins the loaded model to prevent LRU eviction. Defaults to `false`. |
| `save_options` | No | All | Boolean. If true, saves recipe options to `recipe_options.json`. Any previously stored value for `model_name` is replaced. |
| `ctx_size` | No | llamacpp, flm, ryzenai-llm | Context size for the model. Overrides the default value. |
| `llamacpp_backend` | No | llamacpp | LlamaCpp backend to use (`vulkan`, `rocm`, `metal` or `cpu`). |
| `llamacpp_args` | No | llamacpp | Custom arguments to pass to llama-server. The following are NOT allowed: `-m`, `--port`, `--ctx-size`, `-ngl`, `--jinja`, `--mmproj`, `--embeddings`, `--reranking`. |
| `whispercpp_backend` | No | whispercpp | WhisperCpp backend: `npu` or `cpu` on Windows; `cpu` or `vulkan` on Linux. Default is `npu` if supported. |
| `whispercpp_args` | No | whispercpp | Custom arguments to pass to whisper-server. The following are NOT allowed: `-m`, `--model`, `--port`. Example: `--convert`. |
| `steps` | No | sd-cpp | Number of inference steps for image generation. Default: 20. |
| `cfg_scale` | No | sd-cpp | Classifier-free guidance scale for image generation. Default: 7.0. |
| `width` | No | sd-cpp | Image width in pixels. Default: 512. |
| `height` | No | sd-cpp | Image height in pixels. Default: 512. |
| `merge_args` | No | All | Boolean. If true (default), `*_args` values from global config and per-model config are merged (per-model takes priority). If false, per-model `*_args` replace global `*_args` entirely. |

**Setting Priority:**

When loading a model, settings are applied in this priority order:
1. Values explicitly passed in the `load` request (highest priority)
2. Per-model values configurable in `recipe_options.json` (see below for details)
3. Values from environment variables or server startup arguments (see [Server Configuration](../guide/configuration/README.md))
4. Default hardcoded values in `lemond` (lowest priority)


### Per-model options

You can configure recipe-specific options on a per-model basis. Lemonade manages a file called `recipe_options.json` in the user's Lemonade cache (default: `~/.cache/lemonade`). The available options depend on the model's recipe:

```json
{
  "user.Qwen2.5-Coder-1.5B-Instruct": {
    "ctx_size": 16384,
    "llamacpp_backend": "vulkan",
    "llamacpp_args": "-np 2 -kvu"
  },
  "Qwen3-Coder-30B-A3B-Instruct-GGUF" : {
    "llamacpp_backend": "rocm"
  },
  "whisper-large-v3-turbo-q8_0.bin": {
    "whispercpp_backend": "npu",
    "whispercpp_args": "--convert"
  }
}
```

Note that model names include any applicable prefix, such as `user.` and `extra.`.

### Example requests

Basic load:

```bash
curl -X POST http://localhost:13305/v1/load \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "Qwen3-0.6B-GGUF"
  }'
```

Load with custom settings:

```bash
curl -X POST http://localhost:13305/v1/load \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "Qwen3-0.6B-GGUF",
    "ctx_size": 8192,
    "llamacpp_backend": "rocm",
    "llamacpp_args": "--flash-attn on --no-mmap"
  }'
```

Load and save settings:

```bash
curl -X POST http://localhost:13305/v1/load \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "Qwen3-0.6B-GGUF",
    "ctx_size": 8192,
    "llamacpp_backend": "vulkan",
    "llamacpp_args": "--no-context-shift --no-mmap",
    "save_options": true
  }'
```

Load a Whisper model with NPU backend and conversion enabled:

```bash
curl -X POST http://localhost:13305/v1/load \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "whisper-large-v3-turbo-q8_0.bin",
    "whispercpp_backend": "npu",
    "whispercpp_args": "--convert"
  }'
```

Load an image generation model with custom settings:

```bash
curl -X POST http://localhost:13305/v1/load \
  -H "Content-Type: application/json" \
  -d '{
    "model_name": "sd-turbo",
    "steps": 4,
    "cfg_scale": 1.0,
    "width": 512,
    "height": 512
  }'
```

### Response format

```json
{
  "status":"success",
  "message":"Loaded model: Qwen3-0.6B-GGUF"
}
```

In case of an error, the status will be `error` and the message will contain the error message.

## `POST /v1/unload`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Explicitly unload a model from memory. This is useful to free up memory while still leaving the server process running (which takes minimal resources but a few seconds to start).

### Parameters

| Parameter | Required | Description |
|-----------|----------|-------------|
| `model_name` | No | Name of the specific model to unload. If not provided, all loaded models will be unloaded. |

### Example requests

Unload a specific model:

```bash
curl -X POST http://localhost:13305/v1/unload \
  -H "Content-Type: application/json" \
  -d '{"model_name": "Qwen3-0.6B-GGUF"}'
```

Unload all models:

```bash
curl -X POST http://localhost:13305/v1/unload
```

### Response format

Success response:

```json
{
  "status": "success",
  "message": "Model unloaded successfully"
}
```

Error response (model not found):

```json
{
  "status": "error",
  "message": "Model not found: Qwen3-0.6B-GGUF"
}
```

In case of an error, the status will be `error` and the message will contain the error message.



## `POST /v1/audio/generations`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Audio Generation API. You provide a text prompt and receive a generated audio clip. The loaded model decides the kind of audio: music with ACE-Step models (e.g. `ACE-Step-Music`), sound effects with ThinkSound models (e.g. `ThinkSound-SFX`).

This endpoint is not part of the OpenAI API (OpenAI's audio endpoints cover speech and transcription only), so it is a Lemonade-specific extension.

> **Performance:** generation runs on the GPU (Vulkan, ROCm, or CUDA) and takes from seconds (short sound effects) to minutes (full-length music) depending on duration and hardware.

### Parameters

| Parameter | Required | Description |
|-----------|----------|-------------|
| `model` | Yes | The audio-generation model to use (e.g., `ThinkSound-SFX`, `ACE-Step-Music`). |
| `prompt` | Yes | Text description of the music or sound effect to generate. |
| `duration` | No | Length of the clip in seconds. Defaults to the backend's native default. |
| `steps` | No | Number of inference steps. Lower is faster, higher can improve quality. |
| `cfg` | No | Classifier-free guidance strength (ThinkSound only). |
| `seed` | No | Random seed for reproducibility. |
| `response_format` | No | Output encoding. Only formats the backend natively produces are accepted (currently `wav`); other values are rejected with `400 Bad Request`. Default: `wav`. |

### Response

On success the raw audio bytes are returned with the matching content type (`audio/wav`). On failure the response is JSON with an `error` object: `400` for invalid requests, `404` for unknown models, `500` when the backend reports an error, and `502` when the backend produces no output.

### Example request

```bash
curl -X POST http://localhost:13305/v1/audio/generations \
  -H "Content-Type: application/json" \
  -d '{
        "model": "ThinkSound-SFX",
        "prompt": "glass shattering on a stone floor",
        "duration": 5,
        "seed": 42
      }' \
  --output clip.wav
```

## `GET /v1/health`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Check the health of the server. This endpoint returns information about loaded models.

### Parameters

This endpoint does not take any parameters.

### Example request

```bash
curl http://localhost:13305/v1/health
```

### Response format

```json
{
  "status": "ok",
  "version":"9.3.3",
  "websocket_port":9000,
  "model_loaded": "Llama-3.2-1B-Instruct-Hybrid",
  "all_models_loaded": [
    {
      "model_name": "Llama-3.2-1B-Instruct-Hybrid",
      "checkpoint": "amd/Llama-3.2-1B-Instruct-awq-g128-int4-asym-fp16-onnx-hybrid",
      "last_use": 1732123456.789,
      "type": "llm",
      "device": "gpu npu",
      "pinned": true,
      "recipe": "ryzenai-llm",
      "pid": 12345,
      "recipe_options": {
        "ctx_size": 4096
      },
      "backend_url": "http://127.0.0.1:8001/v1"
    },
    {
      "model_name": "nomic-embed-text-v1-GGUF",
      "checkpoint": "nomic-ai/nomic-embed-text-v1-GGUF:Q4_K_S",
      "last_use": 1732123450.123,
      "type": "embedding",
      "device": "gpu",
      "pinned": false,
      "recipe": "llamacpp",
      "pid": 12346,
      "recipe_options": {
        "ctx_size": 8192,
        "llamacpp_args": "--no-mmap",
        "llamacpp_backend": "rocm"
      },
      "backend_url": "http://127.0.0.1:8002/v1"
    }
  ],
  "pinned_models": {
    "transcription":0,
    "embedding":0,
    "image":0,
    "llm":1,
    "reranking":0,
    "tts":0
  },
  "max_models": {
    "transcription":1,
    "embedding":1,
    "image":1,
    "llm":1,
    "reranking":1,
    "tts":1
  },
  "telemetry": {
    "enabled": false
  },
  "update_check_done": true
}
```

**Field Descriptions:**

- `status` - Server health status, always `"ok"`
- `version` - Version number of Lemonade Server
- `model_loaded` - Model name of the most recently accessed model
- `update_check_done` - Whether the background HuggingFace model update check has completed at startup. Poll this field after server start to know when `update_available` fields are ready.
- `all_models_loaded` - Array of all currently loaded models with details:
  - `model_name` - Name of the loaded model
  - `checkpoint` - Full checkpoint identifier
  - `last_use` - Unix timestamp of last access (load or inference)
  - `type` - Model type: `"llm"`, `"embedding"`, `"reranking"`, `"transcription"`, `"image"`, or `"tts"`
  - `device` - Space-separated device list: `"cpu"`, `"gpu"`, `"npu"`, or combinations like `"gpu npu"`
  - `pinned` - Boolean indicating if the model is currently pinned to prevent auto-eviction
  - `backend_url` - URL of the backend server process handling this model (useful for debugging)
  - `pid` - The Process ID (PID) of the backend engine handling this model
  - `recipe` - Backend/device recipe used to load the model (e.g., `"ryzenai-llm"`, `"llamacpp"`, `"flm"`)
  - `recipe_options` - Options used to load the model (e.g., `"ctx_size"`, `"llamacpp_backend"`, `"llamacpp_args"`, `"whispercpp_args"`)
- `pinned_models` - Counts of pinned models currently loaded in memory per model type (e.g., `llm`, `embedding`, etc.)
- `max_models` - Maximum number of models that can be loaded simultaneously per type (set via `max_loaded_models` in [Server Configuration](../guide/configuration/README.md)):
  - `llm` - Maximum LLM/chat models
  - `embedding` - Maximum embedding models
  - `reranking` - Maximum reranking models
  - `transcription` - Maximum speech-to-text models
  - `image` - Maximum image models
  - `tts` - Maximum text-to-speech models
- `websocket_port` - *(optional)* Port of the WebSocket server for the [Realtime Audio Transcription API](./openai.md#ws-realtime) and [Log Streaming API](#log-streaming-api-websocket). Only present when the WebSocket server is running. The port is OS-assigned or set via `--websocket-port`.
- `telemetry` - Structured telemetry state object:
  - `enabled` - Boolean indicating if telemetry collection is active
  - `captures` - *(optional)* Array of captured telemetry components (e.g., `["inputs", "outputs", "thinking"]`), only present when `enabled` is `true`.

## `GET /v1/stats`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Performance statistics from the last request.

### Parameters

This endpoint does not take any parameters.

### Example request

```bash
curl http://localhost:13305/v1/stats
```

### Response format

```json
{
  "time_to_first_token": 2.14,
  "tokens_per_second": 33.33,
  "input_tokens": 128,
  "output_tokens": 5,
  "prompt_tokens": 9
}
```

**Field Descriptions:**

- `time_to_first_token` - Time in seconds until the first token was generated
- `tokens_per_second` - Generation speed in tokens per second
- `input_tokens` - Number of tokens processed
- `output_tokens` - Number of tokens generated
- `prompt_tokens` - Total prompt tokens including cached tokens

## `GET /v1/system-stats`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Current host resource usage as measured by the Lemonade Server process. This endpoint is useful for first-party clients and dashboards that need lightweight runtime telemetry without scraping Prometheus.

### Parameters

This endpoint does not take any parameters.

### Example request

```bash
curl http://localhost:13305/v1/system-stats
```

### Response format

```json
{
  "cpu_percent": 12.3,
  "memory_gb": 8.4,
  "gpu_percent": 45.0,
  "vram_gb": 2.1,
  "npu_percent": null
}
```

**Field Descriptions:**

- `cpu_percent` - System CPU utilization percentage, or `null` when unavailable
- `memory_gb` - System RAM currently in use, in GiB
- `gpu_percent` - GPU utilization percentage, or `null` when unavailable
- `vram_gb` - GPU memory currently in use, in GiB, or `null` when unavailable
- `npu_percent` - NPU utilization percentage, or `null` when unavailable

GPU, VRAM, and NPU telemetry availability depends on the operating system and installed drivers. Unsupported values are returned as `null`.

## `GET /metrics`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Prometheus scrape endpoint for Lemonade Server. The endpoint returns Prometheus text exposition format and is intended to be scraped by Prometheus, not by Grafana directly.

Unlike most Lemonade API endpoints, `/metrics` is root-level only. It is not mounted under `/api/v0/`, `/api/v1/`, `/v0/`, or `/v1/`.

`HEAD /metrics` is also supported and returns `200 OK` with an empty body.

### Authentication

If `LEMONADE_API_KEY` is set, `/metrics` requires bearer authentication. Either the regular API key or `LEMONADE_ADMIN_API_KEY` is accepted.

If only `LEMONADE_ADMIN_API_KEY` is set and `LEMONADE_API_KEY` is unset, `/metrics` is accessible without authentication, matching regular API endpoint behavior.

### Polling and Refresh Rate

The `/metrics` endpoint has no internal refresh timer. It renders the latest server state at the moment it is scraped.

Polling frequency is configured in Prometheus via `scrape_interval`, for example:

```yaml
global:
  scrape_interval: 10s
```

Grafana queries Prometheus. Grafana's dashboard refresh controls how often panels query Prometheus, but it does not control how often Prometheus scrapes Lemonade.

### Example request

```bash
curl http://localhost:13305/metrics
```

With API-key auth:

```bash
curl http://localhost:13305/metrics \
  -H "Authorization: Bearer $LEMONADE_API_KEY"
```

### Response format

The response uses Prometheus text exposition format:

```text
# HELP lemonade_server_up Whether the Lemonade server is running.
# TYPE lemonade_server_up gauge
lemonade_server_up 1
# HELP lemonade_server_info Lemonade server build information.
# TYPE lemonade_server_info gauge
lemonade_server_info{version="10.4.0"} 1
```

Content type:

```text
text/plain; version=0.0.4; charset=utf-8
```

### Lemonade Metric Families

The authoritative metric-family list is generated by the `/metrics` implementation in [`src/cpp/server/server.cpp`](../../src/cpp/server/server.cpp). Search for `handle_metrics` and `metrics.describe(...)` to see the current names, types, labels, and descriptions.

Unsupported, unavailable, null, NaN, and infinity values are omitted rather than emitted as samples.

### llama.cpp Backend Metrics

When a loaded model uses the `llamacpp` recipe, Lemonade makes a best-effort scrape of the loaded backend process's private `/metrics` endpoint. Backend scrape failures do not fail the Lemonade `/metrics` response.

Scraped llama.cpp metrics are normalized under the `lemonade_llamacpp_*` prefix and labeled with the same Lemonade model metadata used by `lemonade_model_info`.

Lemonade starts llama.cpp backends with metrics enabled so these backend metrics are available whenever the backend supports them.

## `GET /v1/system-info`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

System information endpoint that provides complete hardware details and device enumeration.

### Example request

```bash
curl "http://localhost:13305/v1/system-info"
```

### Response format

```json
{
  "OS Version": "Windows-10-10.0.26100-SP0",
  "Processor": "AMD Ryzen AI 9 HX 375 w/ Radeon 890M",
  "Physical Memory": "32.0 GB",
  "OEM System": "ASUS Zenbook S 16",
  "BIOS Version": "1.0.0",
  "CPU Max Clock": "5100 MHz",
  "Windows Power Setting": "Balanced",
  "model_storage": {
    "path": "/path/to/models",
    "used_bytes": 123456789,
    "total_bytes": 987654321,
    "free_bytes": 864197532
  },
  "devices": {
    "cpu": {
      "name": "AMD Ryzen AI 9 HX 375 w/ Radeon 890M",
      "cores": 12,
      "threads": 24,
      "available": true,
      "family": "x86_64"
    },
    "amd_gpu": [
      {
        "name": "AMD Radeon(TM) 890M Graphics",
        "vram_gb": 0.5,
        "available": true,
        "family": "gfx1150"
      }
    ],
    "amd_npu": {
      "name": "AMD Ryzen AI 9 HX 375 w/ Radeon 890M",
      "power_mode": "Default",
      "available": true,
      "family": "XDNA2"
    }
  },
  "recipes": {
    "llamacpp": {
      "default_backend": "vulkan",
      "backends": {
        "vulkan": {
          "devices": ["cpu", "amd_gpu"],
          "state": "installed",
          "message": "",
          "action": "",
          "version": "b7869"
        },
        "rocm": {
          "devices": ["amd_gpu"],
          "state": "installable",
          "message": "Backend is supported but not installed.",
          "action": "lemonade backends install llamacpp:rocm"
        },
        "metal": {
          "devices": [],
          "state": "unsupported",
          "message": "Requires macOS",
          "action": ""
        },
        "cpu": {
          "devices": ["cpu"],
          "state": "update_required",
          "message": "Backend update is required before use.",
          "action": "lemonade backends install llamacpp:cpu"
        }
      }
    },
    "whispercpp": {
      "default_backend": "default",
      "backends": {
        "default": {
          "devices": ["cpu"],
          "state": "installable",
          "message": "Backend is supported but not installed.",
          "action": "lemonade backends install whispercpp:default"
        }
      }
    },
    "sd-cpp": {
      "default_backend": "default",
      "backends": {
        "default": {
          "devices": ["cpu"],
          "state": "installable",
          "message": "Backend is supported but not installed.",
          "action": "lemonade backends install sd-cpp:default"
        }
      }
    },
    "flm": {
      "default_backend": "default",
      "backends": {
        "default": {
          "devices": ["amd_npu"],
          "state": "installed",
          "message": "",
          "action": "",
          "version": "1.2.0"
        }
      }
    },
    "ryzenai-llm": {
      "default_backend": "default",
      "backends": {
        "default": {
          "devices": ["amd_npu"],
          "state": "installed",
          "message": "",
          "action": ""
        }
      }
    }
  }
}
```

**Field Descriptions:**

- **System fields:**
  - `OS Version` - Operating system name and version
  - `Processor` - CPU model name
  - `Physical Memory` - Total RAM
  - `OEM System` - System/laptop model name (Windows only)
  - `BIOS Version` - BIOS information (Windows only)
  - `CPU Max Clock` - Maximum CPU clock speed (Windows only)
  - `Windows Power Setting` - Current power plan (Windows only)

- `model_storage` - Drive-level storage information for the active configured model storage path. Values are reported in bytes for storage meters; this is not a recursive sum of Lemonade model files.
  - `path` - Active model storage path from server configuration
  - `used_bytes` - Used bytes on the model-storage drive
  - `total_bytes` - Total capacity of the model-storage drive
  - `free_bytes` - Free bytes available to the Lemonade Server process on the model-storage drive

- `devices` - Hardware devices detected on the system (no software/support information)
  - `cpu` - CPU information (name, cores, threads)
  - `amd_gpu` - Array of AMD GPUs, both integrated and discrete (if present)
  - `nvidia_gpu` - Array of NVIDIA GPUs (if present)
  - `amd_npu` - AMD NPU device (if present)

- `recipes` - Software recipes and their backend support status
  - Each recipe (e.g., `llamacpp`, `whispercpp`, `flm`) contains:
    - `default_backend` - Preferred backend selected by server policy for this system (present when at least one backend is not `unsupported`)
    - `backends` - Available backends for this recipe
      - Each backend contains:
        - `devices` - List of devices **on this system** that support this backend (empty if not supported)
        - `state` - Backend lifecycle state: `unsupported`, `installable`, `update_required`, or `installed`
        - `message` - Human-readable status text for GUI and CLI users. Required for `unsupported`, `installable`, and `update_required`; empty for `installed`.
        - `action` - Actionable user instruction string. For install/update cases this is typically an exact CLI command; for other states it may be empty or another actionable value (for example, a URL).
        - `version` - Installed or configured backend version (when available)
- `cloud` - Cloud OpenAI-compatible providers configured on this server (omitted when no providers are installed). Contains:
  - `providers` - Array, one entry per installed provider:
    - `name` - Provider name used as the model-name prefix (e.g. `fireworks`).
    - `base_url` - Persisted base URL from `config.json`.
    - `env_var` - Canonical environment variable name for this provider's API key (e.g. `LEMONADE_FIREWORKS_API_KEY`). The variable's *name* is reported, never its value.
    - `env_var_set` - `true` if the env var is set in `lemond`'s environment.
    - `runtime_key_set` - `true` if an in-memory key has been supplied via `POST /v1/cloud/auth` this session.
    - `models_discovered` - Number of chat-capable models currently in the catalog for this provider.

## `POST /v1/install`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Install or update a backend for a specific recipe/backend pair, **or** register a cloud OpenAI-compatible provider. The request body is dispatched by the `backend` field: any value other than `"cloud"` is treated as a local backend install.

### Install a local backend

If the backend is already installed but outdated, this endpoint updates it to the configured version.

| Parameter | Required | Description |
|-----------|----------|-------------|
| `recipe` | Yes | Recipe name (for example, `llamacpp`, `flm`, `whispercpp`, `sd-cpp`, `ryzenai-llm`) |
| `backend` | Yes | Backend name within the recipe (for example, `vulkan`, `rocm`, `cpu`, `default`) |
| `stream` | No | If `true`, returns Server-Sent Events with progress. Defaults to `false`. |
| `force` | No | If `true`, bypasses hardware filtering for `unsupported` backends and attempts installation anyway. Defaults to `false`. |

Example request:

```bash
curl -X POST http://localhost:13305/v1/install \
  -H "Content-Type: application/json" \
  -d '{
    "recipe": "llamacpp",
    "backend": "vulkan",
    "stream": false
  }'
```

Response format:

```json
{
  "status":"success",
  "recipe":"llamacpp",
  "backend":"vulkan"
}
```

In case of an error, returns an `error` field with details.

### Install a cloud provider
<sub>![Status](https://img.shields.io/badge/status-experimental-orange)</sub>

Registers an OpenAI-compatible chat provider. The base URL is persisted to `config.json`; the optional `api_key` lives in `lemond` process memory only (cleared on restart). See the [Cloud Offload guide](../guide/configuration/cloud.md) for the full workflow.

| Parameter | Required | Description |
|-----------|----------|-------------|
| `backend` | Yes | Must be the literal string `"cloud"`. |
| `provider` | Yes | Short identifier (e.g. `fireworks`). Used as the model-name prefix. |
| `base_url` | Yes | OpenAI-compatible base URL ending in `/v1` (or equivalent). |
| `api_key` | No | Optional. If set, stored in process memory; honors env-wins precedence (see `/v1/cloud/auth`). |

Example request:

```bash
curl -X POST http://localhost:13305/v1/install \
  -H "Content-Type: application/json" \
  -d '{
    "backend": "cloud",
    "provider": "fireworks",
    "base_url": "https://api.fireworks.ai/inference/v1"
  }'
```

Response format:

```json
{
  "status": "success",
  "backend": "cloud",
  "provider": "fireworks",
  "base_url": "https://api.fireworks.ai/inference/v1",
  "models_discovered": 12,
  "auth_state": {
    "env_var_set": true,
    "runtime_key_set": false
  }
}
```

`models_discovered` is `0` when no API key is resolvable. If `api_key` is supplied but the provider's env var is also set, the response includes a `warning` string explaining the env var took precedence.

## `POST /v1/uninstall`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Uninstall a backend for a specific recipe/backend pair, **or** remove a cloud provider. Dispatched by the `backend` field, mirroring `/v1/install`.

### Uninstall a local backend

If loaded models are using that backend, they are unloaded first.

| Parameter | Required | Description |
|-----------|----------|-------------|
| `recipe` | Yes | Recipe name |
| `backend` | Yes | Backend name |

Example request:

```bash
curl -X POST http://localhost:13305/v1/uninstall \
  -H "Content-Type: application/json" \
  -d '{
    "recipe": "llamacpp",
    "backend": "vulkan"
  }'
```

Response format:

```json
{
  "status":"success",
  "recipe":"llamacpp",
  "backend":"vulkan"
}
```

In case of an error, returns an `error` field with details.

### Uninstall a cloud provider
<sub>![Status](https://img.shields.io/badge/status-experimental-orange)</sub>

Removes the provider record from `config.json`, drops its in-memory API key (if any), and evicts every discovered model for that provider from the cache. Returns 404 if the provider was never installed.

| Parameter | Required | Description |
|-----------|----------|-------------|
| `backend` | Yes | Must be the literal string `"cloud"`. |
| `provider` | Yes | Installed provider name. |

Example request:

```bash
curl -X POST http://localhost:13305/v1/uninstall \
  -H "Content-Type: application/json" \
  -d '{
    "backend": "cloud",
    "provider": "fireworks"
  }'
```

Response format:

```json
{
  "status": "success",
  "backend": "cloud",
  "provider": "fireworks",
  "models_evicted": 12
}
```

## `POST /v1/cloud/auth`
<sub>![Status](https://img.shields.io/badge/status-experimental-orange)</sub>

Set an in-memory API key for a previously-installed cloud provider, and trigger a refresh of that provider's discovered model list. The key lives in `lemond` process memory only — it is never written to disk and is cleared on `lemond` restart. For persistence across restarts, set `LEMONADE_<PROVIDER>_API_KEY` in `lemond`'s environment instead.

### Authentication precedence

If `LEMONADE_<PROVIDER>_API_KEY` is set in `lemond`'s environment, the env var takes precedence and this endpoint returns **409 Conflict** without storing the supplied key. This is the safety guarantee that lets an operator provision a "house" key via env without worrying about a client silently overriding it.

### Parameters

| Parameter | Required | Description |
|-----------|----------|-------------|
| `provider` | Yes | Installed provider name. |
| `api_key` | Yes | API key to store in `lemond` process memory. |

### Example request

```bash
curl -X POST http://localhost:13305/v1/cloud/auth \
  -H "Content-Type: application/json" \
  -d '{
    "provider": "fireworks",
    "api_key": "fw-XXXXX"
  }'
```

### Response format (success — 200)

```json
{
  "provider": "fireworks",
  "auth_state": {
    "env_var_set": false,
    "runtime_key_set": true
  },
  "models_discovered": 12
}
```

### Response format (env-var conflict — 409)

```json
{
  "error": {
    "type": "auth_conflict",
    "env_var": "LEMONADE_FIREWORKS_API_KEY",
    "message": "LEMONADE_FIREWORKS_API_KEY is set in the lemond process; the env var takes precedence and the supplied API key was not stored."
  }
}
```

### Other error responses

| Status | Cause |
|---|---|
| `400` | Body is missing `provider` or `api_key`, or one of them is empty. |
| `404` | Provider is not installed. Call `POST /v1/install` with `backend:"cloud"` first. |

## `DELETE /v1/cloud/auth/{provider}`
<sub>![Status](https://img.shields.io/badge/status-experimental-orange)</sub>

Clear the in-memory API key for a provider. Any env-var-based key (`LEMONADE_<PROVIDER>_API_KEY`) remains in effect. If no env-var key is set, the provider's discovered models are evicted from the catalog since they are no longer authenticatable.

### Example request

```bash
curl -X DELETE http://localhost:13305/v1/cloud/auth/fireworks
```

### Response format

```json
{
  "provider": "fireworks",
  "cleared_runtime_key": true,
  "auth_state": {
    "env_var_set": false,
    "runtime_key_set": false
  }
}
```

`cleared_runtime_key` is `false` when no in-memory key was present (e.g., the only key was from the env var).

## Log Streaming API (WebSocket)
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Stream server logs over WebSocket. Clients connect, send a subscribe message, and receive a snapshot of recent log history followed by live log entries as they occur.

### Connection

The WebSocket server shares the same port as the [Realtime Audio Transcription API](./openai.md#ws-realtime). Discover the port via the [`/v1/health`](#get-v1health) endpoint (`websocket_port` field), then connect:

```
ws://localhost:<websocket_port>/logs/stream
```

After connecting, send a `logs.subscribe` message to start receiving logs.

### Client → Server Messages

| Message Type | Description |
|--------------|-------------|
| `logs.subscribe` | Subscribe to log stream. Optional `after_seq` field to resume from a specific sequence number. |

### Server → Client Messages

| Message Type | Description |
|--------------|-------------|
| `logs.snapshot` | Initial batch of retained log entries (up to 5000). Sent once after subscribing. |
| `logs.entry` | A single live log entry. Sent as new log lines are emitted. |
| `error` | Error message (e.g., invalid subscribe request). |

### Example: Subscribe to Logs

Subscribe from the beginning (full backlog):

```json
{
  "type": "logs.subscribe",
  "after_seq": null
}
```

Resume after a known sequence number (e.g., on reconnect):

```json
{
  "type": "logs.subscribe",
  "after_seq": 1042
}
```

### Example: Snapshot Response

```json
{
  "type": "logs.snapshot",
  "entries": [
    {
      "seq": 1,
      "timestamp": "2025-03-30 14:22:01.123",
      "severity": "Info",
      "tag": "Server",
      "line": "2025-03-30 14:22:01.123 [Info] (Server) Starting Lemonade Server..."
    }
  ]
}
```

### Example: Live Entry

```json
{
  "type": "logs.entry",
  "entry": {
    "seq": 1043,
    "timestamp": "2025-03-30 14:22:05.456",
    "severity": "Info",
    "tag": "Router",
    "line": "2025-03-30 14:22:05.456 [Info] (Router) Model loaded successfully"
  }
}
```

### Log Entry Fields

| Field | Type | Description |
|-------|------|-------------|
| `seq` | integer | Monotonically increasing sequence number. Use for dedup and resume. |
| `timestamp` | string | Formatted timestamp from the log system. |
| `severity` | string | Log level: `Trace`, `Debug`, `Info`, `Warning`, `Error`, `Fatal`. |
| `tag` | string | Log source tag (e.g., `Server`, `Router`, component name). |
| `line` | string | The full formatted log line. |

### Integration Notes

- **Reconnection**: Track the last `seq` received and pass it as `after_seq` on reconnect to avoid duplicate entries.
- **Backlog**: The server retains up to 5000 recent log entries. The snapshot may be smaller if fewer entries exist.
- **Platform availability**: WebSocket log streaming is available on all platforms (Windows, Linux, and macOS).

## `GET /live`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Lightweight liveness probe for load balancers and orchestrators. Unlike [`/v1/health`](#get-v1health), this endpoint does no work beyond confirming the process is up — it does not inspect loaded models or backends — so it is safe to poll at high frequency. `HEAD /live` is also supported and returns `200 OK` with an empty body.

Unlike the other endpoints on this page, `/live` is not versioned and is not mounted under the `/api/v0/`, `/api/v1/`, `/v0/`, `/v1/` prefixes.

### Example request

```bash
curl http://localhost:13305/live
```

### Response format

```json
{"status":"ok"}
```

## Internal Endpoints

Internal endpoints are used for server control and configuration. By default, they are secured by `LEMONADE_ADMIN_API_KEY` (if set) to separate control privileges from standard inference operations.

## `POST /internal/telemetry/flush`
<sub>![Status](https://img.shields.io/badge/status-fully_available-green)</sub>

Forces the in-memory telemetry queue to flush all buffered trace spans immediately to the configured OTLP collector. This call blocks until all currently queued spans are serialized and sent.

#### Parameters

None.

Example request:

```bash
curl -X POST http://localhost:13305/internal/telemetry/flush
```

#### Response Format

Returns a JSON object indicating successful completion of the flush operation:

```json
{
  "status": "flushed"
}
```
