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

# What leaves the machine

The most important security fact about Telys is a negative one: **your vectors, document text, and metadata never cross the network to make search work.** The data path — embedding, indexing, searching, compaction, persistence — runs in-process against the signed native runtime. This page enumerates the only outbound traffic Telys produces.

## The only outbound traffic

Telys reaches the network for three account-and-delivery tasks, and nothing else. Each has a stable host and an environment variable you can repoint.

| Purpose                              | Host (default)      | Env var              | Triggered by                                    | Payload                                                                                                           |
| ------------------------------------ | ------------------- | -------------------- | ----------------------------------------------- | ----------------------------------------------------------------------------------------------------------------- |
| Device-code sign-in                  | `accounts.thyn.ai`  | `TELYS_ACCOUNTS_URL` | `telys login`                                   | The OAuth device-code handshake (RFC 8628) — no user data.                                                        |
| Control plane: keys, device, license | `api.telys.ai`      | `TELYS_API_URL`      | `telys login`, `telys runtime install`          | API-key / device registration and license issuance; your device public key and account identity, never your data. |
| Signed-runtime download              | `packages.telys.ai` | `TELYS_PACKAGES_URL` | `telys runtime install` (skipped with `--file`) | Fetches the signed runtime bundle *down*; you send only the request.                                              |

That is the complete list. Once the runtime and license are cached under `$TELYS_HOME`, none of these hosts is contacted to use Telys — license **verification** is offline, against a key embedded in the wheel.

## What never leaves — the data path

Every operation on your data is local. None makes an outbound call:

| Operation                                                                 | Where it runs                                                          |
| ------------------------------------------------------------------------- | ---------------------------------------------------------------------- |
| `create_collection` / `open_collection` / `save`                          | The runtime, on-disk under your engine path.                           |
| `add` / `add_texts` / `upsert` / `upsert_texts` / `update_texts`          | The runtime; text is embedded on-CPU by the `telys.embedding` kernels. |
| `search` / `search_text` / `ids`                                          | The runtime; the query vector or text is embedded and matched locally. |
| `delete` / `compact` / `build_ivf` / `snapshot` / `tune` / `apply_tuning` | The runtime.                                                           |
| `telys serve`                                                             | Serves over a Unix socket or TCP; makes **no outbound network calls**. |
| `telys mcp` and the five MCP tools                                        | Runs over local stdio.                                                 |

The `AlgentaBigramEmbedder` and `AlgentaMultigramEmbedder` in `telys.embedding` turn text into vectors through the native kernel on your CPU — text is never shipped to an embedding service to be vectorized.

{% hint style="success" %}
Stated plainly: the only bytes Telys sends are the auth handshake during `telys login`, the device/license calls to the control plane, and the one request that pulls the signed runtime down. Your vectors, text, and queries are not among them.
{% endhint %}

## `serve` is inbound-only

`serve(path, ...)` opens a listening socket and answers requests; it never initiates an outbound connection. The transport is length-prefixed JSON over a socket:

* **Unix socket** — created `0o600`, treated as trusted, no token required.
* **TCP** — **requires** an `access_token`; anonymous TCP is refused. The token is compared in constant time.

A served Telys instance is reachable only by clients you allow on a socket you opened; it does not phone home. See [**Auth & network model**](/self-hosting/auth-and-network.md) for the wire format and the token handshake.

## The exception you control: remote embedders

Telys's on-device guarantee covers the engine and its local kernels, not network calls your own code makes. If you wrap a hosted embedding API in a `CallableEmbedder` — for example OpenAI or a remote BGE endpoint — embedding a document or query sends that text to the service you chose:

```python
from telys.embedding import CallableEmbedder, EmbeddingProfile

# This fn calls a REMOTE service — your text leaves the machine here,
# by your code, not by Telys. Use a local embedder to stay on-device.
def embed(texts: list[str]):
    ...  # -> [N, D] float32 from a hosted API

profile = EmbeddingProfile(provider="openai", model_id="text-embedding-3-small",
                           model_version="1", dimension=1536)
remote = CallableEmbedder(embed, profile)
```

To keep the whole path on-device, use the local `telys.embedding` kernels. This is the difference between "Telys sends nothing" (always true) and "your application sends nothing" (true only with local embedders).

## Next steps

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Data residency &#x26; privacy</strong></td><td>Where your data lives and who can read it.</td><td><a href="/pages/czd8vgdLG6PP6tkAwVVq">/pages/czd8vgdLG6PP6tkAwVVq</a></td></tr><tr><td><strong>On-device &#x26; offline-first</strong></td><td>Why the data path never needs the network.</td><td><a href="/pages/8qFzJkRN9mhP0vZqJwZv">/pages/8qFzJkRN9mhP0vZqJwZv</a></td></tr><tr><td><strong>Environment variables</strong></td><td>Every host and path you can point elsewhere.</td><td><a href="/pages/51C3pUeevJC3K2vq5RRC">/pages/51C3pUeevJC3K2vq5RRC</a></td></tr><tr><td><strong>Auth &#x26; network model</strong></td><td>How <code>serve</code> authenticates inbound clients.</td><td><a href="/pages/N6BRLlIY4N7N32k9EspF">/pages/N6BRLlIY4N7N32k9EspF</a></td></tr></tbody></table>

Next: see where your data rests in [**Data residency & privacy**](/security/data-residency-privacy.md).


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