Messages

The main endpoint. Wire-compatible with Anthropic's Messages API, so anything the official SDKs can send, you can send.

POST https://ai.dijitul.uk/v1/messages

Making a request

curl https://ai.dijitul.uk/v1/messages \
  -H "x-api-key: $GATEWAY_API_KEY" \
  -H "content-type: application/json" \
  -d '{
    "model": "claude-sonnet-4-6",
    "max_tokens": 1024,
    "system": "You are a careful legal assistant. Cite the clause you rely on.",
    "messages": [
      {"role": "user", "content": "Summarise the termination clause."}
    ]
  }'

Parameters

Name	Type	Required	Description
`model`	string	required	A model alias from GET /v1/models.
`messages`	array	required	The conversation. Alternating user and assistant turns.
`max_tokens`	integer	required	Maximum tokens to generate. Counts towards your allowance only if produced.
`system`	string or array	optional	System prompt. Accepts a plain string or an array of text blocks.
`stream`	boolean	optional	Stream the response as server-sent events.
`temperature`	number	optional	0 to 1. Lower is more deterministic.
`top_p`	number	optional	Nucleus sampling. Prefer temperature or this, not both.
`top_k`	integer	optional	Sample from the top K options.
`stop_sequences`	array	optional	Strings that stop generation.
`tools`	array	optional	Tool definitions the model may call.
`tool_choice`	object	optional	auto, any, or a named tool.
`thinking`	object	optional	Extended thinking configuration, where the model supports it.
`metadata`	object	optional	Passed through. Do not put personal data here — it is not redacted.

Response

{
  "id": "msg_01XyZ...",
  "type": "message",
  "role": "assistant",
  "model": "claude-sonnet-4-6",
  "content": [{ "type": "text", "text": "The termination clause..." }],
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 412,
    "output_tokens": 288,
    "cache_read_input_tokens": 0,
    "cache_creation_input_tokens": 0
  }
}

model is echoed back as the alias you requested, not the provider's internal identifier.

Gateway headers

Alongside the standard response, every call carries headers describing how it was handled. x-gateway-regions in particular means your own logs can evidence where each request was processed, rather than relying on a claim on our website.

x-request-id: req_01k9m2p7...
x-gateway-residency: uk
x-gateway-regions: eu-west-2
x-gateway-model: claude-sonnet-4-6
x-gateway-privacy-mode: tokenise
x-gateway-pii-detected: 3

Streaming

Set stream: true, or use your SDK's streaming helper.

with client.messages.stream(
    model="claude-sonnet-4-6",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Explain UK GDPR Article 28."}],
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)

The wire format is Anthropic's, unchanged:

event: message_start
data: {"type":"message_start","message":{"id":"msg_01...","model":"claude-sonnet-4-6","usage":{"input_tokens":412,"output_tokens":0}}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Article 28 "}}

event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"end_turn"},"usage":{"output_tokens":288}}

event: message_stop
data: {"type":"message_stop"}

Under tokenise, redacted values are restored as the stream passes through us, including when a token spans several chunks.

Tool use

{
  "model": "claude-sonnet-4-6",
  "max_tokens": 1024,
  "tools": [{
    "name": "lookup_matter",
    "description": "Fetch a matter by its reference.",
    "input_schema": {
      "type": "object",
      "properties": { "reference": { "type": "string" } },
      "required": ["reference"]
    }
  }],
  "messages": [{ "role": "user", "content": "What is the status of matter 24/1180?" }]
}

Tool definitions are treated as developer-authored schema and are not scanned for personal data. Tool inputs the model produces are, so a value the model copies out of a redacted prompt is restored before it reaches you.

Images

Base64 image blocks are supported on every model in the catalogue and pass through untouched. Note that PII detection does not read images — a scanned document is forwarded as pixels, so treat image content as unredacted.

Counting tokens

POST https://ai.dijitul.uk/v1/messages/count_tokens

Free, not metered, and not rate limited. Useful for cost estimation before sending.

curl https://ai.dijitul.uk/v1/messages/count_tokens \
  -H "x-api-key: $GATEWAY_API_KEY" \
  -H "content-type: application/json" \
  -d '{"model":"claude-sonnet-4-6","messages":[{"role":"user","content":"How long is this?"}]}'

The count reflects the request after redaction, so it matches what you will actually be billed for.