M311 step 1 — lift a tag that is standing on its own

A tag was shown twice: once as the `#todo` you typed and once as a chip. The
chip moved to the top of the card in 23fd2da; now the text goes — but only
when the tag was the whole line.

THE RULE: a line containing nothing but tags and whitespace is removed.
Anything else is untouched.

That is the conservative reading of "standalone" and it is the operator's:
"only lift standalone tags, leave mid-sentence ones alone". The looser
reading, also stripping a trailing tag off a prose line, is rejected because
the text does not say which kind it is — `buy milk #grocery` is filing,
`remember to call #mom` is the sentence's object, and lifting the second
leaves "remember to call". Mangling a sentence to save a duplicate chip is a
bad trade.

Two guards. A line inside a ``` fence is never touched: a `#tag` there is a
shell comment in somebody's snippet, and deleting it would eat a line of
their example. And a note that is NOTHING but tags keeps its text rather than
being blanked — a duplicated chip beats an empty card.

WHY THIS IS NOT JUST A TEXT EDIT. `via_tag` labels are DERIVED from the body:
reconcile detaches any row no longer backed by a `#tag`, and the picker only
manages `via_tag=False` rows. So a naive lift deletes every tag on the next
save, and leaves them unremovable until then.

Resolved by giving `via_tag` a sharper meaning — backed by text still in the
body — rather than deleting it:

  standalone  lifted, attached as an ORDINARY label. Nothing derives it any
              more because nothing is left to derive it from.
  inline      left in place, still derived, still detached when its text goes.

Which costs nothing elsewhere, because both editors already gate their remove
button on `!via_tag` (NoteEditor.vue:618, EditorChrome.kt:349). A lifted tag
gets its × for free — and needs it, since deleting the text is no longer a
way to remove one. No wire change, no column drop, no UI change.

A tag that GRADUATES from inline to standalone is the sharp edge: its row has
to be flipped before the detach pass, or the same row is dropped for no longer
being in the body. That is the bug, and there is a test on it.

The lift and the display_title re-derivation both live inside the function,
which is renamed to admit it mutates the body. All seven call sites derive
display_title BEFORE calling, so anywhere else and every note would be named
after a line that had just been deleted. Spreading a derived-value update
across seven write paths is the failure #2965 named: "easy to miss, and it is
the common one".

Existing notes lift lazily, on their next save. The migration that does the
rest is step 2, and the core's own copy of the rule is step 3.

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

src/thoughtsync/notes/__init__.py

@@ -72,7 +72,7 @@ from .import_export import (
     _usec_to_dt,
 )
 from .tags import (
-    _reconcile_tags,
+    _lift_and_reconcile_tags,
     parse_tags,
 )
 from .recurrence import REMINDER_RECURRENCES, next_occurrence, normalize_recurrence
@@ -87,7 +87,7 @@ __all__ = [
     "normalize_color",
     "normalize_recurrence",
     "next_occurrence",
-    "_reconcile_tags",
+    "_lift_and_reconcile_tags",
     "_serialize_notes",
     "_safe_filename",
     "_attachment_ext",
@@ -418,7 +418,7 @@ async def create_note():
         db.add(note)
         await db.flush()  # assign note.id before writing links
         # The FOLDED body: an item can carry a #tag too.
-        await _reconcile_tags(db, note)
+        await _lift_and_reconcile_tags(db, note)
         await db.commit()
         await db.refresh(note)
         # After the commit, never before it: the note is saved and the response is
@@ -473,7 +473,7 @@ async def update_note(note_id: str):
             note.recurrence = normalize_recurrence(data["recurrence"])
         if "body" in data:
             note.display_title = derive_display_title(note.body)
-            await _reconcile_tags(db, note)
+            await _lift_and_reconcile_tags(db, note)
         # Version history: snapshot the PRE-edit body, once per editing session
         # rather than once per write — see revisions.should_snapshot. Writing often
         # is what lets a client autosave instead of hoarding text until it closes.
@@ -532,7 +532,7 @@ async def restore_revision(note_id: str, rev_id: str):
         db.add(NoteRevision(note_id=note.id, body=note.body))
         note.body = rev.body
         note.display_title = derive_display_title(note.body)
-        await _reconcile_tags(db, note)
+        await _lift_and_reconcile_tags(db, note)
         await db.commit()
         await db.refresh(note)
         return jsonify(await _serialize_note(db, note))
@@ -586,7 +586,7 @@ async def _rewrite_body(db, note: Note, body: str):
         db.add(NoteRevision(note_id=note.id, body=old_body))
     note.body = body
     note.display_title = derive_display_title(body)
-    await _reconcile_tags(db, note)
+    await _lift_and_reconcile_tags(db, note)
     await db.commit()
     await db.refresh(note)
     if note.body != old_body: