Web editor: a typed #tag shows as a chip, and # suggests existing tags (#5913, #5914)

The tag row under the text was a copy of the note's labels taken when the
editor opened. A #tag in the body becomes a tag on the server's side of a
save, so the copy never learned of it until the note was reopened. Every
save now hands its note back, and the row is refreshed from it.

Typing # in a prose block or a checklist item opens the tags that already
exist: prefix matches first, busiest first. Arrows move, Enter or Tab puts
the tag in, Esc closes only the menu. The grammar and ranking live in
notes/tags.ts with tests, so the menu never offers a tag the server would
not derive.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/components/NoteEditor.vue

@@ -13,7 +13,9 @@ import { RECURRENCES } from "../notes/recurrence";
 import { takeMorphOrigin } from "../composables/useEditorMorph";
 import { prefersReducedMotion } from "../composables/useReducedMotion";
 import type { Note, NoteLabel, NoteRevision } from "../stores/notes";
-import { labelChipClasses } from "../notes/colors";
+import { labelChipClasses, labelDotClasses } from "../notes/colors";
+import { insertTag, suggestTags, tagQueryAt, type TagQuery } from "../notes/tags";
+import { useLabelsStore } from "../stores/labels";
 import { canEditText, isOwnNote } from "../notes/sharing";
 import {
   afterEnter,
@@ -46,7 +48,15 @@ const body = computed(() => joinBlocks(blocks.value));
 function setBody(text: string): void {
   blocks.value = splitBlocks(text);
 }
+// The tag row. Refreshed from every note the server hands back, not only taken when
+// the editor opens: a `#tag` typed into the body becomes a tag on the SERVER's side of
+// a save, so the copy taken at mount never learns of it (#5913). The store's own copy
+// can't stand in for this, because a note that leaves the current lens on save (a tag
+// removed while looking at that tag) is dropped from the store.
 const labelList = ref<NoteLabel[]>(props.note ? [...props.note.labels] : []);
+function takeLabels(saved: Note): void {
+  labelList.value = [...saved.labels];
+}
 const saving = ref(false);
 const root = ref<HTMLElement | null>(null);
 // One element per block, keyed by the block's id — the only thing about a block that
@@ -113,7 +123,8 @@ const liveNote = computed<Note>(() =>
     ? (notes.items.find((n) => n.id === noteId.value) ?? props.note ?? draftNote.value)
     : draftNote.value,
 );
-const bodyPlaceholder = "Take a note…";
+// The one hint that `#` does anything, short of typing one (Scribe #2949).
+const bodyPlaceholder = "Take a note…  # to tag it";
 
 // Sharing (#5174). Someone else's note: at `edit` its text and checklist are theirs to
 // change and nothing else is; at `view` it is read-only. The server enforces both —
@@ -145,6 +156,7 @@ async function createFromFields(): Promise<void> {
   const created = await notes.create({ body: body.value });
   noteId.value = created.id;
   baseline.value = { body: created.body };
+  takeLabels(created);
 }
 
 // Ensure a persisted note exists (for rich actions mid-compose). Returns its id, or
@@ -175,8 +187,9 @@ async function flush(): Promise<void> {
   if (!changed) return;
   saving.value = true;
   try {
-    await notes.saveEdit(noteId.value as string, { body: nextBody });
+    const saved = await notes.saveEdit(noteId.value as string, { body: nextBody });
     baseline.value = { body: nextBody };
+    takeLabels(saved);
   } finally {
     saving.value = false;
   }
@@ -355,6 +368,89 @@ function onProseInput(index: number, e: Event): void {
   const el = e.target as HTMLTextAreaElement;
   setText(index, el.value);
   grow(el);
+  readTag(index, el);
+}
+
+function onTaskInput(index: number, e: Event): void {
+  const el = e.target as HTMLInputElement;
+  setText(index, el.value);
+  readTag(index, el);
+}
+
+// ---- # tag suggestions ----
+//
+// Typing `#` in any field opens a list of the tags that already exist, so a note is
+// filed under `#groceries` rather than a new `#grocery` beside it. Which text counts
+// as a tag being typed, which tags are offered and how one is put in are all in
+// notes/tags.ts, where they are tested; this is only the menu.
+const labels = useLabelsStore();
+const tagAt = ref<{ index: number; query: TagQuery } | null>(null);
+const tagPick = ref(0);
+// Where the menu sits: under the field being typed in. Measured against the block
+// list, which is the menu's positioned parent.
+const tagMenuTop = ref(0);
+const tagMatches = computed(() => (tagAt.value ? suggestTags(labels.items, tagAt.value.query.query) : []));
+
+function readTag(index: number, el: HTMLTextAreaElement | HTMLInputElement): void {
+  const caret = el.selectionStart ?? el.value.length;
+  const query = editable.value && el.selectionEnd === caret ? tagQueryAt(el.value, caret) : null;
+  if (!query) {
+    tagAt.value = null;
+    return;
+  }
+  // The capture window has no shell around it to load the tags first.
+  if (!labels.loaded) void labels.load();
+  if (tagAt.value?.index !== index || tagAt.value.query.start !== query.start) tagPick.value = 0;
+  tagAt.value = { index, query };
+  tagMenuTop.value = el.offsetTop + el.offsetHeight;
+}
+
+/** Moving the caret without typing can leave a tag or enter one. */
+function onFieldKeyup(index: number, e: KeyboardEvent): void {
+  if (["ArrowLeft", "ArrowRight", "Home", "End"].includes(e.key)) {
+    readTag(index, e.target as HTMLTextAreaElement | HTMLInputElement);
+  }
+}
+
+function pickTag(name: string): void {
+  const at = tagAt.value;
+  if (!at) return;
+  const block = blocks.value[at.index];
+  const next = insertTag(block.text, at.query, name);
+  setText(at.index, next.text);
+  tagAt.value = null;
+  const el = blockEls.get(block.id);
+  void nextTick(() => {
+    if (!el) return;
+    el.focus();
+    el.setSelectionRange(next.caret, next.caret);
+    if (el instanceof HTMLTextAreaElement) grow(el);
+  });
+}
+
+/**
+ * The menu's keys, taken before the field's own. True when the key was the menu's.
+ *
+ * Esc closes only the menu: stopped here, it never reaches the panel's Esc, which
+ * would close the whole editor. Enter with a modifier is left alone, since those are
+ * the editor's save shortcuts.
+ */
+function onTagKey(e: KeyboardEvent): boolean {
+  const options = tagMatches.value;
+  if (!tagAt.value || !options.length) return false;
+  if (e.key === "ArrowDown") tagPick.value = (tagPick.value + 1) % options.length;
+  else if (e.key === "ArrowUp") tagPick.value = (tagPick.value - 1 + options.length) % options.length;
+  else if ((e.key === "Enter" || e.key === "Tab") && !e.shiftKey && !e.ctrlKey && !e.metaKey)
+    pickTag(options[tagPick.value].name);
+  else if (e.key === "Escape") tagAt.value = null;
+  else return false;
+  e.preventDefault();
+  e.stopPropagation();
+  return true;
+}
+
+function closeTagMenu(): void {
+  tagAt.value = null;
 }
 
 /**
@@ -368,6 +464,7 @@ function onProseInput(index: number, e: Event): void {
  * however many lines became checkboxes and would otherwise keep its old height.
  */
 function onProseBlur(index: number): void {
+  closeTagMenu();
   if (!editable.value) return;
   const promoted = promoteTasks(blocks.value, index);
   if (promoted === blocks.value) return;
@@ -377,12 +474,23 @@ function onProseBlur(index: number): void {
 
 /** Compose: Shift+Enter saves the note and starts a fresh one (rapid capture). */
 function onProseKeydown(e: KeyboardEvent): void {
+  if (onTagKey(e)) return;
   if (isCreate.value && e.key === "Enter" && e.shiftKey) {
     e.preventDefault();
     void commitAndContinue();
   }
 }
 
+function onTaskKeydown(index: number, e: KeyboardEvent): void {
+  if (onTagKey(e)) return;
+  if (e.key === "Enter") {
+    e.preventDefault();
+    onTaskEnter(index);
+  } else if (e.key === "Backspace") {
+    onTaskBackspace(index, e);
+  }
+}
+
 /** Enter on an item makes the next one; on an EMPTY item it ends the list. */
 function onTaskEnter(index: number): void {
   if (!editable.value) return;
@@ -436,9 +544,11 @@ async function onLabelsChange(next: NoteLabel[]) {
   const tagIds = new Set(tagLabels.map((lb) => lb.id));
   const merged = [...next.filter((lb) => !tagIds.has(lb.id)), ...tagLabels];
   labelList.value = merged;
-  await notes.setLabels(
-    id,
-    merged.map((lb) => lb.id),
+  takeLabels(
+    await notes.setLabels(
+      id,
+      merged.map((lb) => lb.id),
+    ),
   );
 }
 async function removeLabel(id: string) {
@@ -526,6 +636,7 @@ async function restoreRevisionAt(revId: string) {
   if (!id) return;
   const updated = await notes.restoreRevision(id, revId);
   setBody(updated.body);
+  takeLabels(updated);
   baseline.value = { body: updated.body };
   void loadRevisions(); // the pre-restore state became a new revision
 }
@@ -646,7 +757,7 @@ function revPreview(rev: NoteRevision): string {
         <!-- The body, as fields and checkboxes rather than as markup. A checklist
              item is a real input; a run of prose is one textarea, so typing a
              paragraph still feels like typing a paragraph. -->
-        <div class="flex flex-col gap-1">
+        <div class="relative flex flex-col gap-1">
           <template v-for="(block, i) in blocks" :key="block.id">
             <div v-if="block.checked !== null" class="group/item flex items-center gap-2">
               <input
@@ -664,9 +775,11 @@ function revPreview(rev: NoteRevision): string {
                 :readonly="!editable"
                 class="min-w-0 flex-1 bg-transparent text-sm leading-relaxed outline-none"
                 :class="block.checked ? 'text-neutral-400 line-through' : ''"
-                @input="setText(i, ($event.target as HTMLInputElement).value)"
-                @keydown.enter.prevent="onTaskEnter(i)"
-                @keydown.backspace="onTaskBackspace(i, $event)"
+                @input="onTaskInput(i, $event)"
+                @keydown="onTaskKeydown(i, $event)"
+                @keyup="onFieldKeyup(i, $event)"
+                @click="readTag(i, $event.target as HTMLInputElement)"
+                @blur="closeTagMenu"
               />
               <button
                 v-if="editable"
@@ -688,9 +801,44 @@ function revPreview(rev: NoteRevision): string {
               class="w-full resize-none overflow-hidden bg-transparent text-sm leading-relaxed outline-none placeholder:text-neutral-400"
               @input="onProseInput(i, $event)"
               @keydown="onProseKeydown"
+              @keyup="onFieldKeyup(i, $event)"
+              @click="readTag(i, $event.target as HTMLTextAreaElement)"
               @blur="onProseBlur(i)"
             />
           </template>
+          <!-- The tags that match what follows a `#`. mousedown.prevent keeps focus
+               in the field, so picking one doesn't blur it and close this first. -->
+          <ul
+            v-if="tagAt && tagMatches.length"
+            role="listbox"
+            aria-label="Matching tags"
+            class="absolute left-0 z-10 mt-1 max-h-56 w-60 overflow-y-auto rounded-lg border border-neutral-200 bg-white p-1 shadow-lg dark:border-neutral-700 dark:bg-neutral-800"
+            :style="{ top: `${tagMenuTop}px` }"
+          >
+            <li v-for="(t, k) in tagMatches" :key="t.id" role="option" :aria-selected="k === tagPick">
+              <button
+                type="button"
+                tabindex="-1"
+                class="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm"
+                :class="
+                  k === tagPick
+                    ? 'bg-brand/15 text-brand-700 dark:text-brand'
+                    : 'hover:bg-neutral-100 dark:hover:bg-neutral-700'
+                "
+                @mousemove="tagPick = k"
+                @mousedown.prevent="pickTag(t.name)"
+              >
+                <span
+                  class="h-2.5 w-2.5 shrink-0 rounded-full border border-black/10 dark:border-white/15"
+                  :class="labelDotClasses(t)"
+                ></span>
+                <span class="truncate">#{{ t.name }}</span>
+                <span v-if="t.count" class="ml-auto shrink-0 text-xs tabular-nums text-neutral-400">{{
+                  t.count
+                }}</span>
+              </button>
+            </li>
+          </ul>
         </div>
         <!-- No checklist component. The items are blocks above, each one line of the
              body, which is what lets a list sit between two paragraphs (M304). -->

frontend/src/notes/tags.test.ts

@@ -0,0 +1,62 @@
+import { describe, expect, it } from "vitest";
+
+import { insertTag, suggestTags, tagQueryAt } from "./tags";
+
+describe("the tag being typed", () => {
+  it("is found at the caret, with what has been typed so far", () => {
+    expect(tagQueryAt("buy milk #gro", 13)).toEqual({ start: 9, end: 13, query: "gro" });
+  });
+
+  it("counts a bare # at the start or after a space", () => {
+    expect(tagQueryAt("#", 1)).toEqual({ start: 0, end: 1, query: "" });
+    expect(tagQueryAt("milk #", 6)).toEqual({ start: 5, end: 6, query: "" });
+  });
+
+  it("runs on past the caret to the end of the word", () => {
+    expect(tagQueryAt("#grocery list", 3)).toEqual({ start: 0, end: 8, query: "gr" });
+  });
+
+  it("is not a tag where the grammar says it is not", () => {
+    expect(tagQueryAt("a#b", 3)).toBeNull(); // no space before the #
+    expect(tagQueryAt("#2024", 5)).toBeNull(); // starts with a digit
+    expect(tagQueryAt("##x", 3)).toBeNull();
+    expect(tagQueryAt("# heading", 9)).toBeNull(); // a space ends it
+    expect(tagQueryAt("plain words", 5)).toBeNull();
+  });
+});
+
+describe("which tags are offered", () => {
+  const tags = [
+    { name: "grocery", count: 3 },
+    { name: "groceries", count: 9 },
+    { name: "hungry", count: 1 },
+    { name: "to do", count: 50 },
+    { name: "Café", count: 2 },
+  ];
+
+  it("puts names that start with the query first, busiest first", () => {
+    expect(suggestTags(tags, "gr").map((t) => t.name)).toEqual(["groceries", "grocery", "hungry"]);
+  });
+
+  it("matches without regard to case", () => {
+    expect(suggestTags(tags, "CAF").map((t) => t.name)).toEqual(["Café"]);
+  });
+
+  it("leaves out a tag already typed in full, and names the body can't hold", () => {
+    expect(suggestTags(tags, "grocery").map((t) => t.name)).toEqual([]);
+    expect(suggestTags(tags, "").map((t) => t.name)).not.toContain("to do");
+  });
+});
+
+describe("inserting a picked tag", () => {
+  it("replaces the whole token and leaves the caret after a space", () => {
+    const text = "buy #gr milk";
+    const at = tagQueryAt(text, 7)!;
+    expect(insertTag(text, at, "groceries")).toEqual({ text: "buy #groceries milk", caret: 14 });
+  });
+
+  it("adds a space at the end of the text", () => {
+    const at = tagQueryAt("#gr", 3)!;
+    expect(insertTag("#gr", at, "grocery")).toEqual({ text: "#grocery ", caret: 9 });
+  });
+});

frontend/src/notes/tags.ts

@@ -4,3 +4,71 @@
 export function foldTag(name: string): string {
   return name.toLowerCase();
 }
+
+// The body-tag grammar, as `line_tags` in core/src/local/derive.rs defines it and
+// `INLINE_RE` in markdown.ts mirrors it: a `#` at the start or after whitespace, a
+// letter, then letters, digits, `_` and `-`.
+const TAG_CHAR = /[\p{Alphabetic}\p{N}_-]/u;
+const WHOLE_TAG = /^\p{Alphabetic}[\p{Alphabetic}\p{N}_-]*$/u;
+
+/** The `#tag` the caret is in the middle of typing: where its `#` is, where the
+ *  token ends (it may run on past the caret), and the part typed so far. */
+export interface TagQuery {
+  start: number;
+  end: number;
+  query: string;
+}
+
+/**
+ * The tag being typed at `caret`, or null when the caret is not in one.
+ *
+ * A bare `#` counts, with an empty query: that is the moment a suggestion list is
+ * most use, because it is the moment someone has not yet decided what to type.
+ * Anything the grammar would not derive (`a#b`, `#2024`, `##x`) is not a tag here
+ * either, so the menu never offers to finish something the server would ignore.
+ */
+export function tagQueryAt(text: string, caret: number): TagQuery | null {
+  let i = caret;
+  while (i > 0 && TAG_CHAR.test(text[i - 1])) i--;
+  if (i === 0 || text[i - 1] !== "#") return null;
+  const hash = i - 1;
+  if (hash > 0 && !/\s/.test(text[hash - 1])) return null;
+  const query = text.slice(i, caret);
+  if (query && !/^\p{Alphabetic}/u.test(query)) return null;
+  let end = caret;
+  while (end < text.length && TAG_CHAR.test(text[end])) end++;
+  return { start: hash, end, query };
+}
+
+/**
+ * The existing tags worth offering for `query`, best first.
+ *
+ * Names that start with what was typed come before names that merely contain it;
+ * within each, the tag on the most notes first. A tag already typed out in full is
+ * left out, so Enter after a finished `#grocery` is a new line rather than a
+ * pointless completion. A tag whose name the body grammar can't hold (one made in
+ * the picker as "to do") is left out too: inserting `#to do` would derive `#to`.
+ */
+export function suggestTags<T extends { name: string; count?: number }>(
+  tags: readonly T[],
+  query: string,
+  limit = 8,
+): T[] {
+  const q = foldTag(query);
+  const prefix = (t: T) => (foldTag(t.name).startsWith(q) ? 0 : 1);
+  return tags
+    .filter((t) => {
+      const f = foldTag(t.name);
+      return WHOLE_TAG.test(t.name) && f !== q && f.includes(q);
+    })
+    .sort((a, b) => prefix(a) - prefix(b) || (b.count ?? 0) - (a.count ?? 0) || a.name.localeCompare(b.name))
+    .slice(0, limit);
+}
+
+/** `text` with the tag at `at` replaced by `#name`, and where the caret goes after
+ *  it. A space follows unless one is already there, so typing simply continues. */
+export function insertTag(text: string, at: TagQuery, name: string): { text: string; caret: number } {
+  const after = text.slice(at.end);
+  const insertion = `#${name}${/^\s/.test(after) ? "" : " "}`;
+  return { text: text.slice(0, at.start) + insertion + after, caret: at.start + insertion.length };
+}

frontend/src/stores/notes.ts

@@ -158,8 +158,10 @@ export const useNotesStore = defineStore("notes", () => {
   async function mutate(
     id: string,
     changes: Partial<Pick<Note, "body" | "pinned" | "archived" | "remind_at" | "recurrence">>,
-  ): Promise<void> {
-    reconcile(await repo.notes.update(id, changes));
+  ): Promise<Note> {
+    const note = await repo.notes.update(id, changes);
+    reconcile(note);
+    return note;
   }
 
   const setPinned = (id: string, pinned: boolean) => mutate(id, { pinned });
@@ -179,8 +181,10 @@ export const useNotesStore = defineStore("notes", () => {
     reconcile(await repo.notes.snoozeReminder(id, minutes));
   }
 
-  async function setLabels(id: string, labelIds: string[]): Promise<void> {
-    reconcile(await repo.notes.setLabels(id, labelIds));
+  async function setLabels(id: string, labelIds: string[]): Promise<Note> {
+    const note = await repo.notes.setLabels(id, labelIds);
+    reconcile(note);
+    return note;
   }
 
   async function updateItem(id: string, itemId: string, changes: { checked: boolean }): Promise<void> {