# `Nous.Plugins.InputGuard.Strategies.Pattern`
[🔗](https://github.com/nyo16/nous/blob/v0.17.1/lib/nous/plugins/input_guard/strategies/pattern.ex#L1)

Regex-based pattern matching strategy for detecting prompt injection and jailbreak attempts.

Ships with default patterns for common injection techniques including instruction
override, role reassignment, DAN jailbreaks, and prompt extraction attempts.

> #### Best-effort, not authorization {: .warning}
>
> This strategy is **defense-in-depth**, not a security boundary. Regex
> matching over natural language is trivially evaded — by synonyms,
> rephrasing, leetspeak, whitespace/zero-width splitting, translation, or
> encoding — and the default patterns only catch well-known phrasings.
>
> A `:safe` result means "no known-bad pattern matched", NOT "this input is
> trusted". Never gate a security or authorization decision on it. Treat
> retrieved/tool/user content as untrusted regardless of what this strategy
> returns, and rely on real controls (sandboxing, permissions, output
> validation) for actual enforcement.

## Configuration

  * `:patterns` — Full override of the default pattern list. Each entry is a
    `{regex, label}` tuple where `label` describes what the pattern detects.
  * `:extra_patterns` — Additional patterns to append to the defaults.
    Use this when you want to keep the built-in patterns and add your own.

## Examples

    # Use defaults
    {Nous.Plugins.InputGuard.Strategies.Pattern, []}

    # Add extra patterns
    {Nous.Plugins.InputGuard.Strategies.Pattern,
      extra_patterns: [
        {~r/sudo mode/i, "sudo mode attempt"}
      ]}

    # Full override
    {Nous.Plugins.InputGuard.Strategies.Pattern,
      patterns: [
        {~r/ignore all previous/i, "instruction override"}
      ]}

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*Consult [api-reference.md](api-reference.md) for complete listing*