Field formats

Field formats annotate a component's string inputs so their JSON Schema says what shape the value is (an LLM tool or a config author sees the intent) and the value is validated. A format is Annotated metadata - there is no registry, so using and extending them is just types.

from warpweft.formats import Ipv4, Uuid


class Lookup(AComponent[EmptySettings, str, dict]):
    @invocable
    async def locate(self, host: Ipv4, ticket: Uuid) -> Report: ...

The input schema then carries {"type": "string", "format": "ipv4"}, and a bad value is rejected (at the MCP boundary, arguments are validated against the input model before the call).

Shipped formats

Only the standard JSON Schema string formats, with stdlib validators: Date, Time, DateTime, Email, Hostname, Ipv4, Ipv6, Uri, Uuid, Regex, JsonPointer.

Custom formats

Define your own - a Format value plus an optional validator - and use it in Annotated. No registration:

from typing import Annotated
from warpweft.formats import Format


def _validate_sha256(value: str) -> None:
    if len(value) != 64 or not all(c in "0123456789abcdefABCDEF" for c in value):
        raise ValueError("expected a SHA-256 hex digest")


Sha256 = Annotated[str, Format("hash-sha256", "SHA-256 hex digest.", _validate_sha256)]

A Format without a validator only annotates the schema; with one, the value is validated wherever the model is (component invocation via a tool, warpweft schema, direct model use).