test(cron): regression test for run_one_job secret scope

Asserts the behavior contract that run_one_job installs a profile secret
scope around run_job under multiplexing (so resolve_runtime_provider's
get_secret does not fail-close with UnscopedSecretError) and tears it
down afterward. Mutation-verified: fails on unmodified main with the
exact UnscopedSecretError, passes with the fix.

tests/cron/test_run_one_job.py

@@ -117,3 +117,46 @@ def test_run_one_job_exception_marks_failure(monkeypatch):
 
     assert ok is False
     assert marks == [("j6", False)]
+
+
+def test_run_one_job_installs_secret_scope_under_multiplex(monkeypatch, tmp_path):
+    """Regression: under profile isolation (multiplex active), run_one_job must
+    execute run_job inside a profile secret scope so credential reads
+    (resolve_runtime_provider -> get_secret) don't fail-close with
+    UnscopedSecretError, and must tear the scope down afterward.
+
+    Behavior contract: a scope is present during run_job and absent after,
+    regardless of the concrete secret values.
+    """
+    from agent import secret_scope as ss
+
+    # Point cron's home resolution at a profile whose .env carries a secret.
+    (tmp_path / ".env").write_text("OPENROUTER_BASE_URL=https://openrouter.ai/api/v1\n")
+    monkeypatch.setattr(s, "_get_hermes_home", lambda: tmp_path)
+
+    scope_during_run = {}
+
+    def fake_run_job(job):
+        # This is where resolve_runtime_provider() would read a secret. Prove a
+        # scope is installed and the profile's secret resolves without raising.
+        scope_during_run["scope"] = ss.current_secret_scope()
+        scope_during_run["base_url"] = ss.get_secret("OPENROUTER_BASE_URL")
+        return (True, "out", "final", None)
+
+    monkeypatch.setattr(s, "run_job", fake_run_job)
+    monkeypatch.setattr(s, "save_job_output", lambda jid, out: f"/tmp/{jid}.txt")
+    monkeypatch.setattr(s, "_deliver_result", lambda *a, **k: None)
+    monkeypatch.setattr(s, "mark_job_run", lambda *a, **k: None)
+
+    ss.set_multiplex_active(True)
+    try:
+        ok = s.run_one_job({"id": "j7", "name": "t"})
+    finally:
+        ss.set_multiplex_active(False)
+
+    assert ok is True
+    # Scope was installed during run_job and the profile secret resolved.
+    assert scope_during_run["scope"] is not None
+    assert scope_during_run["base_url"] == "https://openrouter.ai/api/v1"
+    # And it was torn down after run_one_job returned (no leak).
+    assert ss.current_secret_scope() is None