Decorate a client

guard.decorate wraps a completions function. It is called with the arguments it would have received, so you keep using the provider SDK directly and no base URL is rewritten.

const create = fw.guard.decorate(
  (body: OpenAI.Chat.ChatCompletionCreateParamsNonStreaming) =>
    openai.chat.completions.create(body),
  { baseUrl: "https://api.openai.com/v1", provider: "openai" },
);

const completion = await create({
  model: "gpt-4o-mini",
  messages: [{ role: "user", content: userInput }],
});

if ("error" in completion) {
  return res.status(400).json(completion);
}

create = fw.guard.decorate(
    lambda **body: openai.chat.completions.create(**body),
    DecorateOptions(base_url="https://api.openai.com/v1", provider="openai"),
)

completion = create(
    model="gpt-4o-mini",
    messages=[{"role": "user", "content": user_input}],
)

The request is inspected first. The guard then refuses the call, redacts the body and forwards it, or forwards it untouched, according to onMatch. A sync function gets a sync wrapper and a coroutine function gets an async one, so an AsyncOpenAI client stays async.

Streaming

A stream is teed, not buffered. Each chunk reaches you before it is recorded, so decoration adds no latency.

const createStream = fw.guard.decorate(
  (body: OpenAI.Chat.ChatCompletionCreateParamsStreaming) =>
    openai.chat.completions.create(body),
  { provider: "openai" },
);

const stream = await createStream({ model: "gpt-4o-mini", messages, stream: true });

for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content ?? "");
}

Sanitise in place

With onMatch: "sanitise" the body is rewritten before it is sent. Provider parameters survive untouched and only matched spans change.

const create = fw.guard.decorate(
  (body: OpenAI.Chat.ChatCompletionCreateParamsNonStreaming) =>
    openai.chat.completions.create(body),
  { onMatch: "sanitise" },
);

Anthropic

The same decorator wraps the Anthropic SDK. messages.create and messages.stream both work. The request layout understands the Messages API: a top-level system parameter (a string or a list of text blocks), and content blocks that nest text inside tool_result and tool_use.

const create = fw.guard.decorate(
  (body: Anthropic.MessageCreateParamsNonStreaming) =>
    anthropic.messages.create(body),
  { baseUrl: "https://api.anthropic.com", provider: "anthropic" },
);

Tool results and replayed tool calls are scanned too, because they are first-class indirect injection surfaces. Image and document payloads are not: base64 is neither text nor a plausible carrier for an instruction.

Options

Option	Purpose
`baseUrl`	The wrapped client’s base URL. Recorded for attribution, never rewritten.
`provider`	A label such as `openai` or `anthropic`. Inferred from the request shape if omitted.
`onMatch`	Overrides the guard-level action for this call.
`capture`	Overrides capture settings for this call. See Telemetry and capture.
`cloak`	Protect personal data in the request. See Cloak.

Get started

Guard

Cloak

Integrations

Operations

Streaming

Sanitise in place

Anthropic

Options

​Streaming

​Sanitise in place

​Anthropic

​Options

Streaming

Sanitise in place

Anthropic

Options