hermes-agent/agent/delegation_context.py

"""Context-local state for delegate_task child execution.

A Hermes process may itself be a Kanban dispatcher worker with HERMES_KANBAN_* in
os.environ. In-process delegate_task children and cron jobs fired via
``cronjob(action="run")`` are NOT dispatcher-owned, so identity gates must fail
closed for them without mutating the process-global environment.
"""
from __future__ import annotations

import os
from contextlib import contextmanager
from contextvars import ContextVar, Token
from typing import Iterator, Mapping, MutableMapping, overload

_DELEGATED_CHILD_CONTEXT: ContextVar[bool] = ContextVar("hermes_delegated_child_context", default=False)
# Any in-process execution that is NOT the dispatcher-owned worker (cron jobs). Kept separate
# so delegate_task-specific behaviour (subprocess env scrubbing, its error strings) is unchanged.
_NON_DISPATCHER_OWNED_CONTEXT: ContextVar[bool] = ContextVar("hermes_non_dispatcher_owned_context", default=False)

DELEGATED_CHILD_ENV_MARKER = "HERMES_DELEGATED_CHILD_CONTEXT"

KANBAN_ENV_KEYS: tuple[str, ...] = (
    "HERMES_KANBAN_TASK", "HERMES_KANBAN_RUN_ID", "HERMES_KANBAN_CLAIM_LOCK",
    "HERMES_KANBAN_GOAL_MODE", "HERMES_KANBAN_GOAL_MAX_TURNS",
)


@contextmanager
def delegated_child_context(session_id: str | None = None) -> Iterator[None]:
    """Mark child execution and isolate its task-local session identity. Even a context
    entered without an id must restore the parent's session ContextVar (child
    construction calls ``set_current_session_id``)."""
    token = _DELEGATED_CHILD_CONTEXT.set(True)
    try:
        from gateway.session_context import scoped_current_session_id  # lazy: it calls is_delegated_child_context()

        with scoped_current_session_id(session_id):
            yield
    finally:
        _DELEGATED_CHILD_CONTEXT.reset(token)


def is_delegated_child_context() -> bool:
    """Return True while code is running for a delegate_task child."""
    return bool(_DELEGATED_CHILD_CONTEXT.get())


def enter_non_dispatcher_owned_context() -> Token[bool]:
    """Token form of :func:`non_dispatcher_owned_context` for long try/finally scopes."""
    return _NON_DISPATCHER_OWNED_CONTEXT.set(True)


def exit_non_dispatcher_owned_context(token: Token[bool]) -> None:
    """Restore the flag saved by :func:`enter_non_dispatcher_owned_context`."""
    _NON_DISPATCHER_OWNED_CONTEXT.reset(token)


@contextmanager
def non_dispatcher_owned_context() -> Iterator[None]:
    """Mark in-process execution that does NOT own the dispatcher's Kanban task; without it
    a cron agent run inside a worker is misread as that worker (kanban toolset force-added,
    ``kanban_complete`` defaulting to its task). ContextVar-scoped rather than clearing
    os.environ, which the worker's claim heartbeat and concurrent readers share."""
    token = enter_non_dispatcher_owned_context()
    try:
        yield
    finally:
        exit_non_dispatcher_owned_context(token)


def is_dispatcher_owned_worker_context() -> bool:
    """The single predicate every ``HERMES_KANBAN_*`` identity gate should use."""
    return not (is_delegated_child_process_context() or _NON_DISPATCHER_OWNED_CONTEXT.get())


def is_delegated_child_process_context() -> bool:
    """Return True in this process or a subprocess spawned by a child."""
    return bool(_DELEGATED_CHILD_CONTEXT.get()) or bool(os.environ.get(DELEGATED_CHILD_ENV_MARKER))


def _fenced_kanban_root() -> str:
    """The board root this process's Kanban lineage lives under (``kanban_home()``); ``"1"`` when it
    cannot be resolved, which readers treat as "fence every board" (the pre-path marker)."""
    try:
        from hermes_cli.kanban_db import kanban_home
        return str(kanban_home())
    except Exception:
        return "1"


def scrub_kanban_env(env: Mapping[str, str] | MutableMapping[str, str]) -> dict[str, str]:
    """Remove worker identity, retaining board/location and an inherited write fence.

    TASK absence alone would promote a descendant to an orchestrator. The marker
    survives later execs, including scripts that remove TASK themselves. This is
    cooperative runtime scoping, not confinement of code with direct SQLite access.

    The marker's value is the fenced board ROOT, so the fence applies to the lineage's
    board and not to every Kanban DB the descendant touches: a child running a repro
    against a temp ``HERMES_HOME`` got a silently read-only board there. An inherited
    path-valued marker is kept (a grandchild that moved HERMES_HOME must not re-fence
    onto its scratch root and unfence the real one).
    """
    cleaned = {k: v for k, v in env.items() if k not in KANBAN_ENV_KEYS}
    inherited = str(env.get(DELEGATED_CHILD_ENV_MARKER) or "")
    cleaned[DELEGATED_CHILD_ENV_MARKER] = inherited if inherited and inherited != "1" else _fenced_kanban_root()
    return cleaned


def kanban_path_is_fenced(path: "os.PathLike[str] | str") -> bool:
    """Whether Kanban mutations at *path* (a board DB or board-metadata root) are denied for this
    process: always for an in-process delegate child (the parent's own board); for a spawned
    descendant only when *path* is the dispatcher-pinned ``HERMES_KANBAN_DB`` or lies under the
    fenced root the marker carries. A legacy ``"1"`` marker fences everything."""
    if _DELEGATED_CHILD_CONTEXT.get():
        return True
    marker = os.environ.get(DELEGATED_CHILD_ENV_MARKER, "")
    if not marker:
        return False
    if marker == "1":
        return True
    from pathlib import Path
    target = Path(path).expanduser().resolve()
    pinned = os.environ.get("HERMES_KANBAN_DB", "").strip()
    if pinned and target == Path(pinned).expanduser().resolve():
        return True
    try:
        target.relative_to(Path(marker).expanduser().resolve())
    except ValueError:
        return False
    return True


@overload
def delegated_child_subprocess_env(env: Mapping[str, str]) -> dict[str, str]: ...


@overload
def delegated_child_subprocess_env(env: None = None) -> dict[str, str] | None: ...


def delegated_child_subprocess_env(
    env: Mapping[str, str] | MutableMapping[str, str] | None = None,
) -> dict[str, str] | None:
    """Carry worker/delegate descendant denial across a real process spawn.

    Location and credentials are untouched; callers retain their existing secret policy.
    Dispatcher workers and supervised tool transports grant their own explicit scope.
    """
    if not (is_delegated_child_process_context() or os.environ.get("HERMES_KANBAN_TASK")
            or (env and (env.get("HERMES_KANBAN_TASK") or env.get(DELEGATED_CHILD_ENV_MARKER)))):
        return None if env is None else dict(env)
    return scrub_kanban_env(os.environ if env is None else env)