feat(temp): give each download task its own temp directory

Each dl run works in temp/task_<id>/, removed on every exit path. Orphans from hard-killed processes are swept via lock liveness, and env clear temp skips directories whose task is still running.

tests/core/test_task_temp.py

@@ -0,0 +1,174 @@
+"""Tests for per-task temp directories.
+
+Each run gets a private dir that is removed on every exit path. The sweep reclaims
+dirs from hard-killed processes via lock liveness, and `env clear temp` skips the
+dir of a task that is still running.
+"""
+
+from __future__ import annotations
+
+import os
+import time
+from pathlib import Path
+
+import pytest
+from filelock import FileLock
+
+from unshackle.commands.env import clear_directory
+from unshackle.core.config import config
+from unshackle.core.temp import LOCK_NAME, TASK_PREFIX, is_stale, sweep_task_dirs, task_temp_dir
+
+pytestmark = pytest.mark.unit
+
+
+@pytest.fixture
+def temp_root(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
+    root = tmp_path / "temp"
+    root.mkdir()
+    monkeypatch.setattr(config.directories, "temp", root)
+    return root
+
+
+def backdate(path: Path) -> None:
+    stamp = time.time() - 120
+    os.utime(path, (stamp, stamp))
+
+
+def make_task_dir(root: Path, name: str = "task_deadbeef", lock: bool = True) -> Path:
+    task_dir = root / name
+    task_dir.mkdir()
+    if lock:
+        (task_dir / LOCK_NAME).touch()
+    return task_dir
+
+
+def test_task_dir_created_repointed_and_restored(temp_root: Path) -> None:
+    with task_temp_dir() as task_dir:
+        assert task_dir.parent == temp_root
+        assert task_dir.name.startswith(TASK_PREFIX)
+        assert config.directories.temp == task_dir
+    assert config.directories.temp == temp_root
+    assert not task_dir.exists()
+
+
+def test_task_dir_removed_on_exception(temp_root: Path) -> None:
+    with pytest.raises(ValueError):
+        with task_temp_dir() as task_dir:
+            (task_dir / "partial.mp4").write_bytes(b"x")
+            raise ValueError("boom")
+    assert not task_dir.exists()
+    assert config.directories.temp == temp_root
+
+
+def test_task_dir_removed_on_keyboard_interrupt(temp_root: Path) -> None:
+    with pytest.raises(KeyboardInterrupt):
+        with task_temp_dir() as task_dir:
+            raise KeyboardInterrupt
+    assert not task_dir.exists()
+    assert config.directories.temp == temp_root
+
+
+def test_sweep_removes_unlocked_stale_dir(temp_root: Path) -> None:
+    task_dir = make_task_dir(temp_root)
+    (task_dir / "leftover.mp4").write_bytes(b"x")
+    backdate(task_dir)
+    sweep_task_dirs(temp_root)
+    assert not task_dir.exists()
+
+
+def test_sweep_skips_locked_dir(temp_root: Path) -> None:
+    task_dir = make_task_dir(temp_root)
+    lock = FileLock(task_dir / LOCK_NAME)
+    lock.acquire()
+    backdate(task_dir)
+    try:
+        assert is_stale(task_dir) is False
+        sweep_task_dirs(temp_root)
+        assert task_dir.exists()
+    finally:
+        lock.release()
+
+
+def test_sweep_skips_young_unlocked_dir(temp_root: Path) -> None:
+    task_dir = make_task_dir(temp_root)
+    assert is_stale(task_dir) is False
+    sweep_task_dirs(temp_root)
+    assert task_dir.exists()
+
+
+def test_sweep_removes_stale_dir_without_lock_file(temp_root: Path) -> None:
+    task_dir = make_task_dir(temp_root, lock=False)
+    backdate(task_dir)
+    assert is_stale(task_dir) is True
+    sweep_task_dirs(temp_root)
+    assert not task_dir.exists()
+
+
+def test_sweep_ignores_non_task_entries(temp_root: Path) -> None:
+    loose_file = temp_root / "leftover.mp4"
+    loose_file.write_bytes(b"x")
+    other_dir = temp_root / "not_a_task"
+    other_dir.mkdir()
+    backdate(loose_file)
+    backdate(other_dir)
+    sweep_task_dirs(temp_root)
+    assert loose_file.exists()
+    assert other_dir.exists()
+
+
+@pytest.mark.skipif(os.name == "nt", reason="symlink creation needs privileges on Windows")
+def test_sweep_never_follows_symlinked_task_dir(temp_root: Path, tmp_path: Path) -> None:
+    target = tmp_path / "victim"
+    target.mkdir()
+    (target / "precious.mkv").write_bytes(b"data")
+    link = temp_root / "task_evil"
+    link.symlink_to(target)
+    backdate(target)
+    sweep_task_dirs(temp_root)
+    assert (target / "precious.mkv").exists()
+    assert not (target / LOCK_NAME).exists()
+
+
+@pytest.mark.skipif(os.name == "nt", reason="symlink creation needs privileges on Windows")
+def test_clear_directory_unlinks_symlinked_dir_without_following(temp_root: Path, tmp_path: Path) -> None:
+    target = tmp_path / "victim"
+    target.mkdir()
+    (target / "precious.mkv").write_bytes(b"data")
+    link = temp_root / "task_evil"
+    link.symlink_to(target)
+    backdate(target)
+    files_count, _ = clear_directory(temp_root)
+    assert not link.exists()
+    assert (target / "precious.mkv").exists()
+    assert files_count == 1
+
+
+def test_clear_directory_skips_locked_task_dir(temp_root: Path) -> None:
+    task_dir = make_task_dir(temp_root)
+    (task_dir / "in_flight.mp4").write_bytes(b"xyz")
+    lock = FileLock(task_dir / LOCK_NAME)
+    lock.acquire()
+    backdate(task_dir)
+    loose_file = temp_root / "leftover.mp4"
+    loose_file.write_bytes(b"1234")
+    try:
+        files_count, freed_bytes = clear_directory(temp_root)
+    finally:
+        lock.release()
+    assert task_dir.exists()
+    assert (task_dir / "in_flight.mp4").exists()
+    assert not loose_file.exists()
+    assert files_count == 1
+    assert freed_bytes == 4
+
+
+def test_clear_directory_removes_stale_task_dir(temp_root: Path) -> None:
+    task_dir = make_task_dir(temp_root)
+    (task_dir / "orphan.mp4").write_bytes(b"12345")
+    backdate(task_dir)
+    files_count, freed_bytes = clear_directory(temp_root)
+    assert not task_dir.exists()
+    assert temp_root.is_dir()
+    # glob("**/*") never matches dotfiles, so .lock is not counted
+    assert files_count == 1
+    assert freed_bytes == 5