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

# Detectors

> A detector is a reusable, configured instance of a catalog detector. It is detection-only — it decides what it finds, never what to do. Enforcement is decided by the policy that references it.

A **detector** is a reusable, named instance you create from one entry in the
[detector catalog](/trustguard/detectors/overview) (e.g. `prompt_guard`) plus the
**settings** you configure (thresholds, entity lists, allow/deny lists, …). You
create and edit detectors in the console's **Detectors** screen, and the same
detector can be referenced by many [policies](/trustguard/concepts/policies).

<Note>
  Detectors are **detection-only**. A detector decides *what* it finds and how
  confident it is — it never decides whether to block, mask, or allow. That
  decision lives on the [policy](/trustguard/concepts/policies) that uses the
  detector (its **Gates** and **Detectors** tabs). This separation lets you reuse
  one well-tuned detector across many policies with different enforcement.
</Note>

## What defines a detector

| Property     | Values                                                       | Meaning                                                                                                                                                                              |
| ------------ | ------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Type**     | one entry from the [catalog](/trustguard/detectors/overview) | Which catalog detector this is an instance of (e.g. `prompt_guard`, `data_loss_prevention`). Fixed — you can't change its code, only its settings. Sent to the API as `plugin_slug`. |
| **Name**     | free text                                                    | A human label (e.g. *"Jailbreak — strict"*) so you can tell two detectors of the same type apart.                                                                                    |
| **Settings** | type-specific                                                | The detection's configuration — thresholds, entity lists, keyword/regex lists, and so on. The console renders and validates the form.                                                |
| **Enabled**  | on / off                                                     | A disabled detector is skipped everywhere it's referenced.                                                                                                                           |

A detector does **not** carry a mode, a direction, or a protocol. Those belong
to the [policy](/trustguard/concepts/policies) rule that puts the detector to
work (the **Input** / **Output** phase). At request time the collector must send
matching `direction` on `/v1/evaluate` — [TrustGate](/trustguard/integrations/gateway)
sets it automatically; [application](/trustguard/integrations/application) and
other collectors must set it themselves.

## Settings

Every catalog detector exposes its own settings schema (the catalog API,
`GET /v1/plugins`, returns each detector type and its fields). Examples:

* `prompt_guard`, `toxicity` — a `threshold` in `[0, 1]`.
* `data_loss_prevention` — which PII entities to detect/mask, plus custom
  keyword/regex rules.
* `prompt_moderation` — keyword/regex lists and/or NeuralTrust topic thresholds.

See each detector's full settings on its
[category page](/trustguard/detectors/overview).

## Mutable (transform-capable) detectors

Most detectors only read the payload. A **mutable** detector can rewrite it —
today only [`data_loss_prevention`](/trustguard/detectors/data-loss-prevention),
which masks matched values in flight and populates `transformed_payload`.

Only a mutable detector can be used with the **Transform** action in a policy;
choosing Transform for any other detector is rejected when you save the policy.

## Putting a detector to work

Creating a detector doesn't run it. To evaluate traffic you reference the
detector from a [policy](/trustguard/concepts/policies):

1. Open a policy → **Detectors** tab.
2. Pick an **evaluation phase** — **Input** (prompt/request) or **Output**
   (completion/response).
3. Add a rule that selects the detector and an **action** — **Monitor**
   (record a finding only), **Block**, or **Transform** (mutable detectors).
4. Optionally add **conditions** so the rule only runs for certain consumers,
   models, collectors, protocols, or sessions.

Then attach the policy to a [collector](/trustguard/concepts/collectors) so its
traffic is evaluated.