fix(backup): find diskutil, mount and docker in the nightly cron run

stacklets/backup/_cron.py

@@ -49,16 +49,19 @@ def sync_command(stack_bin: Path, log_path: Path) -> str:
     """The shell command a cron entry runs for the nightly sync.
 
     Both paths are double-quoted so an install or data directory
-    containing spaces doesn't break cron's word-splitting. PATH is
-    prepended with the Homebrew bin so cron's minimal environment finds
-    the Homebrew Python (the system Python on macOS is too old). Output
+    containing spaces doesn't break cron's word-splitting. cron starts
+    with PATH=/usr/bin:/bin, so the Homebrew bin goes in front for the
+    Homebrew Python (the system Python on macOS is too old), and the
+    directories of the other tools the sync calls by name go after it:
+    ``/usr/local/bin`` for docker (OrbStack and Docker Desktop link it
+    there), ``/usr/sbin`` for diskutil, ``/sbin`` for mount. Output
     appends to ``log_path`` so a misbehaving scheduled run leaves a
     trail. Shared by on_install and on_start so the entry stays
     byte-identical across reinstalls.
     """
     homebrew_bin = _homebrew_prefix() / "bin"
     return (
-        f'PATH="{homebrew_bin}:$PATH" '
+        f'PATH="{homebrew_bin}:$PATH:/usr/local/bin:/usr/sbin:/sbin" '
         f'"{stack_bin}" backup sync >> "{log_path}" 2>&1'
     )
 

tests/unit/stacklets/test_backup_install.py

@@ -8,9 +8,12 @@
 
 from __future__ import annotations
 
+import subprocess
 import sys
 from pathlib import Path
 
+import pytest
+
 
 REPO_ROOT = Path(__file__).resolve().parents[3]
 sys.path.insert(0, str(REPO_ROOT / "stacklets" / "backup" / "hooks"))
@@ -81,6 +84,21 @@ def test_prepends_homebrew_path(self):
         assert cmd.startswith('PATH="')
         assert "/bin:$PATH" in cmd
 
+    @pytest.mark.skipif(not Path("/usr/sbin/diskutil").exists(), reason="macOS only")
+    def test_finds_the_sync_tools_under_crons_path(self, tmp_path):
+        # cron on macOS starts with PATH=/usr/bin:/bin, and the sync calls
+        # diskutil, mount and docker by name. Run the line the way cron
+        # does, with a stand-in for the stack that looks each one up.
+        tools = ["diskutil", "mount"] + (["docker"] if Path("/usr/local/bin/docker").exists() else [])
+        stack = tmp_path / "stack"
+        stack.write_text("#!/bin/sh\n" + "".join(f"command -v {t}\n" for t in tools))
+        stack.chmod(0o755)
+        log = tmp_path / "cron.log"
+        cmd = cron.sync_command(stack, log)
+        subprocess.run(["/usr/bin/env", "-i", "PATH=/usr/bin:/bin", "/bin/sh", "-c", cmd], check=False)
+        found = log.read_text().split()
+        assert [Path(f).name for f in found] == tools
+
     def test_uses_absolute_paths(self):
         # cron's PATH is minimal; relative paths break. The binary, the
         # log destination, and the prepended PATH dirs must all be absolute.