fix: keep postponing when a task cannot be saved

CHANGELOG.md

@@ -8,6 +8,7 @@ and I do try to adhere to [Semantic Versioning](https://semver.org/spec/v2.0.0.h
 ### Fixed
 
 * `interactive manage-tasks`: a parent task postponed together with its child could be postponed once more in its own turn, and with caldav 3.6 this crashed with a "412 Precondition Failed" error.  It is now skipped, with a note.  A task changed on the server in the meantime is reloaded before it is postponed.
+* `interactive manage-tasks` no longer stops with a traceback when the server refuses to store a task it postpones, e.g. with "423 Locked" from a Xandikos server busy with another write.  The task is reported and the rest are still postponed.
 
 ## v1.3.0 - 2026-10-23
 

plann/lib.py

@@ -17,7 +17,7 @@
 import click  ## TODO - this should be removed, eventually
 import icalendar
 from caldav.config import extract_conn_params_from_section
-from caldav.lib.error import ETagMismatchError, NotFoundError, ScheduleTagMismatchError, UidConflictError
+from caldav.lib.error import ETagMismatchError, NotFoundError, PutError, ScheduleTagMismatchError, UidConflictError
 
 from plann.template import Template
 from plann.timespec import (
@@ -376,6 +376,10 @@ def _procrastinate(objs, delay, check_dependent="error", with_children=False, wi
                         ## the child needs it moved, even if postponed already
                         postponed.discard(p.get('UID'))
                         _procrastinate([parent], new_due+max(parent.get_duration()+x.get_duration()+datetime.timedelta(minutes=1), datetime.timedelta(minutes=1)), check_dependent=check_dependent, err_callback=err_callback, confirm_callback=confirm_callback, postponed=postponed, recursivity=recursivity+1)
+                        if p.get('UID') and p.get('UID') not in postponed:
+                            ## the parent could not be saved - trying the child again would only loop
+                            err_callback(f"{summary} not postponed, as the parent could not be saved")
+                            continue
                         _procrastinate([x], new_due, check_dependent=check_dependent, err_callback=err_callback, confirm_callback=confirm_callback, postponed=postponed, recursivity=recursivity+1)
             elif check_dependent == "return":
                 return parent
@@ -396,6 +400,10 @@ def _procrastinate(objs, delay, check_dependent="error", with_children=False, wi
                     continue
                 _procrastinate([x], delay, check_dependent, with_children, with_family, with_parent, err_callback, confirm_callback, postponed=postponed, reload_on_conflict=False, recursivity=recursivity+1)
                 continue
+            except PutError as e:
+                ## i.e. 423 Locked from a busy server - don't abort the rest of the list
+                err_callback(f"{_summary(x)} could not be saved: {e}")
+                continue
             if uid:
                 postponed.add(uid)
         if with_children:

tests/test_lib.py

@@ -429,6 +429,52 @@ def load(*args, **kwargs):
         _procrastinate([t], '10d', err_callback=msgs.append)
         assert any('deleted' in m for m in msgs)
 
+def test_procrastinate_put_error_continues():
+    """A task the server refuses to store (here 423 Locked, from a
+    git-backed Xandikos busy with another write) is reported, and the
+    rest of the list is still postponed"""
+    from caldav.lib import error
+    a = _todo('a')
+    b = _todo('b')
+    msgs = []
+    postponed = set()
+    with patch.object(a, 'save', side_effect=error.PutError("423 Locked")), \
+         patch.object(a, 'set_due', return_value=None), \
+         patch.object(b, 'save') as b_save, patch.object(b, 'set_due', return_value=None):
+        _procrastinate([a, b], '10d', err_callback=msgs.append, postponed=postponed)
+        assert b_save.call_count == 1
+        assert any('could not be saved' in m and '423' in m for m in msgs)
+        assert postponed == {'b'}
+
+def test_procrastinate_parent_put_error():
+    """When the parent the child needs moved cannot be saved, the
+    child is reported as not postponed, and not retried over and over"""
+    from caldav.lib import error
+    parent = _todo('parent')
+    child = _todo('child', related_to='parent')
+    msgs = []
+    with patch.object(child, 'set_due', return_value=parent) as child_set_due, \
+         patch.object(child, 'save') as child_save, \
+         patch.object(parent, 'save', side_effect=error.PutError("423 Locked")) as parent_save, \
+         patch.object(parent, 'set_due', return_value=None):
+        _procrastinate([child], '10d', check_dependent='interactive', err_callback=msgs.append)
+        assert parent_save.call_count == 1
+        assert child_set_due.call_count == 1
+        assert child_save.call_count == 0
+        assert any('not postponed, as the parent could not be saved' in m for m in msgs)
+
+def test_procrastinate_put_error_after_reload():
+    """A PutError on the save after reloading is reported, too"""
+    from caldav.lib import error
+    t = _todo('changed')
+    msgs = []
+    with patch.object(t, 'save', side_effect=[error.ETagMismatchError(), error.PutError("423 Locked")]) as save, \
+         patch.object(t, 'load'), \
+         patch.object(t, 'set_due', return_value=None):
+        _procrastinate([t], '10d', err_callback=msgs.append)
+        assert save.call_count == 2
+        assert any('could not be saved' in m for m in msgs)
+
 def test_procrastinate_without_uid():
     """Tasks without a UID are not taken for one another"""
     a = _todo('a')