fix(cron): resolve the no-override store fallback lazily so late env repoints can't write the real jobs file

Complements ec0227b43 (context-scoped cron store): the ContextVar override
is the right tool for deliberate cross-profile scoping, but with no
override active, _current_cron_store() returned the import-time constants —
so a HERMES_HOME set AFTER cron.jobs import (the filed incident: test
fixtures patching the env too late) still read/wrote the user's real
jobs.json. The fallback now resolves the active profile home fresh via
get_hermes_home() (context-local override, then env) and scopes the store
to it; when the home is unchanged since import, the exact module-level
constants are returned as before (zero change in the common path, and they
remain the documented compatibility surface). use_cron_store() still wins.

Three tests: late env repoint scopes the store; unchanged home returns the
import-time constants identically; an active use_cron_store() override
beats the env.

cron/jobs.py

@@ -116,11 +116,27 @@ _cron_store_override: ContextVar[Optional[_CronStorePaths]] = ContextVar(
 
 
 def _current_cron_store() -> _CronStorePaths:
-    """Return paths pinned to this execution context's profile."""
+    """Return paths pinned to this execution context's profile.
+
+    With no use_cron_store() override active, the active profile home is
+    resolved FRESH via get_hermes_home() (context-local override, then the
+    HERMES_HOME env var) instead of trusting the import-time capture. A test
+    or embedder that re-points HERMES_HOME after this module was imported
+    therefore reads/writes ITS OWN store — not whatever jobs.json the import
+    happened to freeze (the filed incident: fixtures that patched the env too
+    late silently rewrote the user's real jobs file). The module-level
+    constants keep their import-time values as the documented compatibility
+    surface, and the common path (home unchanged since import) still returns
+    them unchanged.
+    """
     override = _cron_store_override.get()
     if override is not None:
         return override
-    return _CronStorePaths(CRON_DIR, JOBS_FILE, OUTPUT_DIR)
+    home = get_hermes_home().resolve()
+    if home == HERMES_DIR:
+        return _CronStorePaths(CRON_DIR, JOBS_FILE, OUTPUT_DIR)
+    cron_dir = home / "cron"
+    return _CronStorePaths(cron_dir, cron_dir / "jobs.json", cron_dir / "output")
 
 
 @contextlib.contextmanager

tests/cron/test_jobs.py

@@ -1945,3 +1945,36 @@ class TestClaimDispatch:
         # At minimum, the good job's record is still intact (no corruption from the bad neighbor)
         loaded = {j["id"]: j for j in load_jobs()}
         assert "good" in loaded
+
+
+class TestLateEnvRepointScopesStore:
+    """A HERMES_HOME set AFTER cron.jobs import must scope the store even
+    without use_cron_store(): fixtures that patch the environment too late
+    previously read/wrote the import-time jobs.json — the user's real file."""
+
+    def test_late_env_repoint_scopes_store(self, tmp_path, monkeypatch):
+        import cron.jobs as jobs
+
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        store = jobs._current_cron_store()
+        expected = tmp_path.resolve() / "cron"
+        assert store.cron_dir == expected
+        assert store.jobs_file == expected / "jobs.json"
+        assert store.output_dir == expected / "output"
+        # the import-time compatibility constants are untouched
+        assert jobs.JOBS_FILE != store.jobs_file
+
+    def test_unchanged_home_returns_import_time_constants(self, monkeypatch):
+        import cron.jobs as jobs
+
+        monkeypatch.setenv("HERMES_HOME", str(jobs.HERMES_DIR))
+        store = jobs._current_cron_store()
+        assert store.jobs_file is jobs.JOBS_FILE
+
+    def test_use_cron_store_override_still_wins(self, tmp_path, monkeypatch):
+        import cron.jobs as jobs
+
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path / "env-home"))
+        with jobs.use_cron_store(tmp_path / "override-home"):
+            store = jobs._current_cron_store()
+            assert store.jobs_file == (tmp_path / "override-home").resolve() / "cron" / "jobs.json"