feat: warn on orphaned RECURRENCE-ID overrides

When `add ical` splits a VCALENDAR, a UID group may hold only
RECURRENCE-ID overrides and no master event.  That usually means the
recurring event was deleted elsewhere without cleaning up its
overrides.  They are still imported as detached occurrences, but a
warning now names the UID and the summaries rather than letting it
pass silently.

Rescued from an unreferenced commit that a rebase left behind on no
branch (1d06e47, 2026-05-21, "fix: warn on orphaned RECURRENCE-ID
overrides during ical import", by Claude Sonnet 4.6), and adapted:
_split_vcal returns ical strings now, so the check runs before the
conversion.  The NotFoundError this data caused on import was fixed in
the caldav library at the time.

Prompt: Repair the PR and apply anything useful from 1d06e47 and 2634df2 into the PR [both are unreferenced commits found while checking stale worktrees and branches for work worth rescuing; 2634df2 held only a superseded roadmap draft and a scratch estimates file, so nothing of it is applied]

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: tobixen

CHANGELOG.md

@@ -10,6 +10,7 @@ and I do try to adhere to [Semantic Versioning](https://semver.org/spec/v2.0.0.h
 * `edit --add-categories`, `--add-resource` and `--add-resources` options (alongside the existing `--add-category`).  A single value containing commas is split by the plural forms (`--add-categories`/`--add-resources`) and kept literal by the singular forms (`--add-category`/`--add-resource`).
 * `select ... list --separator=...` to join the listed items with something other than a newline.  (Ported from the archived development branch.)
 * The interactive edit prompt now advertises the `start` command (kicks off time tracking for the task) and re-prompts afterwards so a follow-up command can be given for the same task.  (Ported from the archived development branch.)
+* `add ical` warns when the imported data holds RECURRENCE-ID overrides with no master event for the same UID - typically left behind when the recurring event was deleted elsewhere.  The overrides are still imported, as detached occurrences.
 * `select --warn-on-missing-uid/--no-warn-on-missing-uid` (default: warn).  A `--uid` that matches nothing in any calendar now prints a warning naming the missing uid(s) to stderr, rather than being silently ignored.  `--abort-on-missing-uid` still takes precedence, and `--no-warn-on-missing-uid` restores the old fully-silent behaviour.  Ref https://github.com/tobixen/plann/issues/42
 * `plann configure`: an interactive configuration mode (EXPERIMENTAL/under-tested) that prompts for connection parameters and writes them to the config file.  The underlying code existed but had been orphaned in the argparse→click migration; it is now wired up again, and the prompted keys match what the caldav library actually reads (so e.g. `ssl_verify_cert` is no longer written under a key that is silently ignored at connect time).
 

plann/lib.py

@@ -138,6 +138,16 @@ def _split_vcal(ical):
                 for tz in ical_cal_stripped.subcomponents:
                     split_by_uid[uid].add_component(tz)
             split_by_uid[uid].add_component(subcomponent)
+    for uid, vcal in split_by_uid.items():
+        components = [x for x in vcal.subcomponents if not isinstance(x, icalendar.Timezone)]
+        has_master = any('RECURRENCE-ID' not in x for x in components)
+        has_exception = any('RECURRENCE-ID' in x for x in components)
+        if has_exception and not has_master:
+            logging.warning(
+                "UID %s has RECURRENCE-ID override(s) but no master event in this calendar: %s. "
+                "The master may have been deleted. Will import as detached occurrence(s).",
+                uid, [str(x.get('SUMMARY', '(no summary)')) for x in components])
+
     ## Return ical strings, like _split_vcals does - the callers hand the
     ## result on to _caldav_objclass()/add_object(), which parse text.
     return [cal.to_ical().decode() for cal in split_by_uid.values()]

tests/test_lib.py

@@ -403,6 +403,26 @@ def test_split_vcal():
     assert(len(output) == 2)
 
 
+def test_split_vcal_warns_on_orphaned_recurrence_id(caplog):
+    """A UID group holding only RECURRENCE-ID overrides has lost its master
+    event - typically deleted by the originating calendar application without
+    cleaning up the overrides.  Import it, but say so."""
+    orphan = todo.replace(
+        'UID:19970901T130000Z-123404@host.com',
+        'UID:19970901T130000Z-123404@host.com\nRECURRENCE-ID:19970415T133000Z')
+    with caplog.at_level('WARNING'):
+        parts = _split_vcal(orphan)
+    assert len(parts) == 1
+    assert 'RECURRENCE-ID' in caplog.text
+    assert '19970901T130000Z-123404@host.com' in caplog.text
+
+    ## a normal object must not warn
+    caplog.clear()
+    with caplog.at_level('WARNING'):
+        _split_vcal(todo)
+    assert caplog.text == ''
+
+
 def test_split_vcal_yields_ical_strings():
     """`add ical` feeds every element of _split_vcal() straight into
     _caldav_objclass(), which parses text - so _split_vcal must yield ical