"""Normalised conversation identity shared across platforms and storage."""

from __future__ import annotations

from dataclasses import dataclass


@dataclass(frozen=True, slots=True)
class ThreadKey:
    """Normalised identity of a conversation scope across platforms.

    ``platform`` is ``"telegram"`` or ``"matrix"``. ``scope`` is the chat/room/user
    identifier as a string. ``thread`` is an optional sub-thread identifier.
    """

    platform: str
    scope: str
    thread: str | None = None

    def __str__(self) -> str:
        parts = [self.platform, self.scope]
        if self.thread:
            parts.append(self.thread)
        return ":".join(parts)