abhigyanpatwari/GitNexus · critical · ValueError

oracle stage parent changed during verification: {item.targe

Error message

oracle stage parent changed during verification: {item.target}

What it means

Same verification pass as error 360, but per-parent-directory: while walking the parents of each staged oracle file (relative.parts[:-1]), every intermediate directory must still be a real directory. A symlink or non-dir parent means the staged path was restructured mid-verification. The harness aborts rather than emit an untrusted result.

Source

Thrown at eval/workflow_bench/oracle_assets.py:501

            view = view[written:]
        os.fchmod(descriptor, 0o400)
        os.fsync(descriptor)
    finally:
        os.close(descriptor)


def _verify_staged_oracle(stage_root: Path, snapshot: TaskOracleSnapshot) -> None:
    root_metadata = stage_root.lstat()
    if stat.S_ISLNK(root_metadata.st_mode) or not stat.S_ISDIR(root_metadata.st_mode):
        raise ValueError("oracle stage root changed during verification")
    for item in snapshot.files:
        relative = PurePosixPath(item.target)
        current = stage_root
        for part in relative.parts[:-1]:
            current /= part
            metadata = current.lstat()
            if stat.S_ISLNK(metadata.st_mode) or not stat.S_ISDIR(metadata.st_mode):
                raise ValueError(f"oracle stage parent changed during verification: {item.target}")
        observed = _read_oracle_file(stage_root, relative)
        if observed != item.payload:
            raise ValueError(f"oracle file changed during verification: {item.target}")


@contextmanager
def staged_task_oracle(worktree: Path, snapshot: TaskOracleSnapshot) -> Iterator[Path]:
    """Materialize a private random oracle root only after the model exits."""

    root = worktree.expanduser().absolute()
    metadata = root.lstat()
    if stat.S_ISLNK(metadata.st_mode) or not stat.S_ISDIR(metadata.st_mode) or root.resolve(strict=True) != root:
        raise ValueError(f"oracle worktree must be a real non-symlink directory: {root}")
    stage_root = root / f".wfbench-oracle-{secrets.token_hex(16)}"
    stage_root.mkdir(mode=0o700)
    stage_root.chmod(0o700)
    primary: BaseException | None = None
    try:

View on GitHub (pinned to d540b00184)

Solutions

1. Use the {item.target} in the message to identify the affected oracle file, then inspect each parent segment under stage_root with `ls -la` / `readlink`.
2. Ensure the worktree is on a real local directory and no other process is mutating it during the run.
3. Audit the agent under test for symlink creation or directory replacement inside the oracle stage path.
4. Re-stage from a fresh clone and re-run.

# Verify every parent of every oracle target is a real dir before staging.
import stat
from pathlib import Path, PurePosixPath

def precheck_parents(stage_root: Path, targets: list[str]) -> None:
    for t in targets:
        cur = stage_root
        for part in PurePosixPath(t).parts[:-1]:
            cur /= part
            # Parents don't have to exist yet (the harness mkdir's them), but if
            # they DO exist they must be real directories.
            try:
                st = cur.lstat()
            except FileNotFoundError:
                continue
            assert stat.S_ISDIR(st.st_mode) and not stat.S_ISLNK(st.st_mode), \
                f'{cur} is not a real directory'

try:
    with staged_task_oracle(worktree, snapshot) as stage:
        ...
except ValueError as exc:
    if 'stage parent changed' in str(exc):
        log.security('oracle parent replaced mid-run: %s', exc)
        invalidate_run()
    raise

When it happens

Trigger: Triggered inside _verify_staged_oracle's parent walk when any intermediate `current /= part` resolves to a symlink or non-directory. Common when a deep oracle path like `a/b/c/d.txt` has had `a` or `b` replaced after staging.

Common situations: An agent under test replaces a directory with a symlink to escape the sandbox; a symlink-based mirror of the worktree; concurrent git operations (checkout/clone) inside the worktree; running on a filesystem with case-folding collisions.

Related errors

• oracle source changed while being captured: {relative}
• oracle stage root changed during verification
• oracle file changed during verification: {item.target}
• oracle root must be a real non-symlink directory: {lexical}
• oracle parents must be real directories: {relative}

AI-assisted analysis of abhigyanpatwari/GitNexus@d540b00184 (2026-08-12). Data as JSON: /api/errors/feaebba202e2017a. Report an issue: GitHub.