# `Condukt.Redactor`
[🔗](https://github.com/tuist/condukt/blob/0.16.5/lib/condukt/redactor.ex#L1)

Behaviour for redacting sensitive data before it is sent to an LLM provider.

A redactor is invoked on outbound message text — user input and tool results
— right before the conversation is handed to the LLM. Assistant output and the
system prompt are left untouched: the LLM has already seen its own prior
responses, and the system prompt is authored by the developer.

Redactors are configured per session at `start_link/1` via the `:redactor`
option. The value can be a module or a `{module, opts}` tuple. When `nil`
(the default), no redaction is performed.

    MyApp.Agent.start_link(redactor: Condukt.Redactors.Regex)

    MyApp.Agent.start_link(redactor: {Condukt.Redactors.Regex, patterns: my_patterns})

## Implementing a redactor

    defmodule MyApp.Redactor do
      @behaviour Condukt.Redactor

      @impl true
      def redact(text, _opts) do
        String.replace(text, ~r/\bsecret-[a-z0-9]+\b/, "[REDACTED]")
      end
    end

Redaction in this version is outbound-only: the original text remains in the
session's stored history. Each turn re-runs the redactor on the messages that
are about to be sent, so secrets never leave the BEAM process.

# `redact`

```elixir
@callback redact(text :: String.t(), opts :: keyword()) :: String.t()
```

Returns `text` with sensitive substrings replaced.

`opts` is the keyword list provided alongside the module in a
`{module, opts}` spec, or `[]` when the spec is a bare module.

# `apply`

Applies a redactor spec to a single string.

The spec is a module implementing the behaviour, a `{module, opts}` tuple, a
list of redactor specs, or `nil`. Returns `text` unchanged when `spec` is
`nil` or an empty list.

# `redact_messages`

Returns `messages` with redaction applied to user input and tool results.

Assistant messages and any non-textual content blocks are returned unchanged.
Tool result content that is not a binary is JSON-encoded before redaction so
embedded secrets in structured output are still caught.

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