"""tree_root.py - derive a repo root from __file__ instead of a host-absolute path."""
from __future__ import annotations

import os


def find_tree_root(start, marker="WORK-QUEUE.md"):
    cur = os.path.realpath(start)
    if os.path.isfile(cur):
        cur = os.path.dirname(cur)
    while True:
        if os.path.isfile(os.path.join(cur, marker)):
            return cur
        parent = os.path.dirname(cur)
        if parent == cur:
            raise FileNotFoundError("marker %r not found in any ancestor of %s" % (marker, start))
        cur = parent


def assert_inside_tree(path, root):
    rp = os.path.realpath(path)
    rr = os.path.realpath(root)
    if rp == rr or rp.startswith(rr + os.sep):
        return rp
    raise ValueError("path %s escapes tree root %s" % (rp, rr))


def portable_seed(root, rel="inbox/seed-2026-09-26.json"):
    return assert_inside_tree(os.path.join(root, rel), root)


if __name__ == "__main__":
    r = find_tree_root(__file__)
    p = portable_seed(r)
    print("root=", r)
    print("seed=", p)