fix(cron): re-derive repeat defaults when a schedule update flips the kind

cron/jobs.py

@@ -1897,6 +1897,38 @@ def _normalize_job_updates(job: Dict[str, Any], updates: Dict[str, Any]) -> None
             updates["repeat"] = {"times": normalize_repeat_value(_rp), "completed": completed}
 
 
+def _rederive_repeat_for_schedule_change(
+    job: Dict[str, Any], updates: Dict[str, Any]
+) -> None:
+    """Re-derive the ``repeat`` default when a schedule update flips the kind.
+
+    ``create_job`` derives it from the schedule kind (once -> 1, recurring -> forever); the update
+    path must honour the same contract, otherwise a one-shot turned recurring keeps its ``times=1``
+    budget and retires after one fire, while a recurring job turned one-shot never completes. An
+    explicit ``repeat`` in the same update wins; a same-kind schedule edit leaves ``repeat`` alone.
+    """
+    if "schedule" not in updates or "repeat" in updates:
+        return
+    new_schedule = updates["schedule"]
+    if isinstance(new_schedule, str):
+        new_schedule = parse_schedule(new_schedule)
+        updates["schedule"] = new_schedule
+    old_kind = (job.get("schedule") or {}).get("kind")
+    new_kind = new_schedule.get("kind")
+    if old_kind == new_kind:
+        return
+    repeat = dict(job.get("repeat") or {})
+    times = repeat.get("times")
+    if new_kind == "once" and times is None:
+        repeat["times"] = 1
+    elif new_kind != "once" and old_kind == "once" and times == 1:
+        repeat["times"] = None
+    else:
+        return
+    repeat.setdefault("completed", 0)
+    updates["repeat"] = repeat
+
+
 def _apply_schedule_update(updated: Dict[str, Any], updates: Dict[str, Any], job_id: str) -> None:
     """Parse a string schedule, refresh ``schedule_display`` and (unless paused) ``next_run_at``."""
     updated_schedule = updated["schedule"]
@@ -1936,6 +1968,7 @@ def update_job(job_id: str, updates: Dict[str, Any]) -> Optional[Dict[str, Any]]
         raise ValueError(f"Cron job field(s) cannot be updated: {', '.join(sorted(bad_fields))}")
 
     def apply(jobs, i, job):
+        _rederive_repeat_for_schedule_change(job, updates)
         _normalize_job_updates(job, updates)
         previous_inference_axes = _normalized_inference_axes(job)
         updated = _apply_skill_fields({**job, **updates})

tests/cron/test_jobs.py

@@ -438,6 +438,61 @@ class TestJobCRUD:
         with pytest.raises(ValueError, match="Invalid repeat"):
             update_job(job["id"], {"repeat": "banana"})
 
+    def test_oneshot_turned_recurring_becomes_forever(self, tmp_cron_dir):
+        """A one-shot budget must not survive a schedule change to a recurring kind.
+
+        create_job derives repeat from the schedule kind; update_job must honour
+        the same contract when the kind flips, otherwise a job "fixed" from a
+        one-shot to `every 15m` keeps times=1 and retires after its first fire.
+        """
+        from cron.jobs import update_job
+
+        job = create_job(prompt="poll", schedule="in 15m")
+        assert job["repeat"]["times"] == 1
+
+        updated = update_job(job["id"], {"schedule": "every 15m"})
+        assert updated["schedule"]["kind"] == "interval"
+        assert updated["repeat"]["times"] is None
+
+    def test_recurring_turned_oneshot_becomes_once(self, tmp_cron_dir):
+        """The reverse flip must gain the one-shot default instead of staying forever."""
+        from cron.jobs import update_job
+
+        job = create_job(prompt="poll", schedule="every 15m")
+        assert job["repeat"]["times"] is None
+
+        updated = update_job(job["id"], {"schedule": "in 15m"})
+        assert updated["schedule"]["kind"] == "once"
+        assert updated["repeat"]["times"] == 1
+
+    def test_explicit_repeat_in_same_update_wins(self, tmp_cron_dir):
+        """An explicit repeat beats the re-derived default on kind flips."""
+        from cron.jobs import update_job
+
+        job = create_job(prompt="poll", schedule="in 15m")
+
+        updated = update_job(job["id"], {"schedule": "every 15m", "repeat": 3})
+        assert updated["repeat"]["times"] == 3
+
+    def test_same_kind_schedule_edit_keeps_repeat(self, tmp_cron_dir):
+        """Re-pointing a recurring schedule at another cadence is not a kind flip."""
+        from cron.jobs import update_job
+
+        job = create_job(prompt="poll", schedule="every 15m", repeat=5)
+
+        updated = update_job(job["id"], {"schedule": "every 30m"})
+        assert updated["schedule"]["kind"] == "interval"
+        assert updated["repeat"]["times"] == 5
+
+    def test_explicit_finite_oneshot_keeps_budget_turned_recurring(self, tmp_cron_dir):
+        """An explicitly finite one-shot (repeat=2) carries its budget to the recurring side."""
+        from cron.jobs import update_job
+
+        job = create_job(prompt="poll", schedule="in 15m", repeat=2)
+
+        updated = update_job(job["id"], {"schedule": "every 15m"})
+        assert updated["repeat"]["times"] == 2
+
     def test_rejects_stale_past_one_shot_at_creation(self, tmp_cron_dir, monkeypatch):
         now = datetime(2026, 3, 18, 4, 30, 0, tzinfo=timezone.utc)
         monkeypatch.setattr("cron.jobs._hermes_now", lambda: now)