Fast, cross-device labelling: type #groceries in a note and it becomes the "groceries" label. The body is the source of truth for tag-labels; manual picker labels stay independent (rule 28 — additive). - note_labels.via_tag (migration 0013) marks tag-sourced attachments. - parse_tags(): #tag at start-of-body or after whitespace, needs a letter (so #2024, URL #frags, mid#word are ignored). unit-tested. - _reconcile_tags() on create + body-update: attach labels for current #tags (find-or-create, case-insensitive), detach tag-labels whose tag was removed; never touches manual (via_tag=false) rows. - label picker (set_note_labels + editor onLabelsChange) now preserves tag-labels on save, so a picker action can't strip a label the #tag still mandates. - serialize via_tag; card/editor chips render tag-labels as "#name", and the editor hides the × on them (remove by editing the tag text). - LabelPicker builds manual NoteLabels (via_tag:false). Fourth and final item of M4.5. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm