"""
Fallback segmentation utilities.

Used for offline tests or snapshot generation when model tokenizers
are unavailable.
"""

from typing import Dict, List


def fallback_token_info(text: str) -> Dict[str, List]:
    """Return minimal token info using UTF-8 codepoint boundaries."""
    boundaries = [0]
    byte_pos = 0
    for ch in text:
        byte_pos += len(ch.encode("utf-8"))
        boundaries.append(byte_pos)
    return {
        "common_boundaries": boundaries,
        "qwen_tokens": [],
        "rwkv_tokens": [],
        "byte_to_qwen": {},
        "byte_to_rwkv": {},
    }