From 9788c20d3c82dd4f247ed609aca1e76b688bb978 Mon Sep 17 00:00:00 2001
From: onenewcode <lovestudy@qq.com>
Date: Fri, 18 Sep 2026 20:05:26 +0800
Subject: [PATCH] feat(mongodb): complete fields in filter and sort bars

---
 .../components/document/DocumentBrowser.vue   | 385 ++++++++-
 .../document/DocumentQueryCompletionMenu.vue  |  81 ++
 .../DocumentBrowserFieldSearch.spec.ts        |   5 +
 .../DocumentBrowserQueryCompletion.spec.ts    | 750 ++++++++++++++++++
 .../mongoDocumentQueryCompletion.spec.ts      | 147 ++++
 apps/desktop/src/lib/mongo/mongoCompletion.ts | 164 +++-
 packages/app-tests/documentBrowser.test.ts    |   8 +-
 7 files changed, 1526 insertions(+), 14 deletions(-)
 create mode 100644 apps/desktop/src/components/document/DocumentQueryCompletionMenu.vue
 create mode 100644 apps/desktop/src/components/document/__tests__/DocumentBrowserQueryCompletion.spec.ts
 create mode 100644 apps/desktop/src/lib/mongo/__tests__/mongoDocumentQueryCompletion.spec.ts

diff --git a/apps/desktop/src/components/document/DocumentBrowser.vue b/apps/desktop/src/components/document/DocumentBrowser.vue
index be32fb5172..765ab4c77c 100644
--- a/apps/desktop/src/components/document/DocumentBrowser.vue
+++ b/apps/desktop/src/components/document/DocumentBrowser.vue
@@ -20,6 +20,7 @@ import QueryLoadingState from "@/components/common/QueryLoadingState.vue";
 import * as api from "@/lib/backend/api";
 import type { DynamoDbIndexInfo, DynamoDbTableDescription } from "@/lib/backend/api";
 import { useConnectionStore } from "@/stores/connectionStore";
+import { getDataGridConditionSuggestionPosition, type DataGridConditionSuggestionPosition } from "@/lib/dataGrid/dataGridConditionSuggestionPosition";
 import { clampSearchSplitWidth } from "@/lib/dataGrid/dataGridSearchSplit";
 import { documentViewerFontStyle } from "@/lib/document/documentViewerFontStyle";
 import { ELASTICSEARCH_DEFAULT_MAX_RESULT_WINDOW, clampDocumentPage, resetElasticsearchDocumentTotals, resolveElasticsearchDocumentTotals } from "@/lib/document/elasticsearchDocumentTotals";
@@ -85,6 +86,18 @@ import {
   serializeMongoDocumentId,
   type MongoInputValue,
 } from "@/lib/mongo/mongoDocumentValues";
+import {
+  buildMongoCompletionItemsFromContext,
+  getMongoDocumentQueryCompletionContext,
+  inferMongoCompletionFields,
+  mongoCompletionNeedsFields,
+  plainMongoCompletionInsertion,
+  readMongoPropertyPrefix,
+  shouldAutoOpenMongoDocumentQueryCompletion,
+  type MongoCompletionField,
+  type MongoCompletionItem,
+  type MongoDocumentQueryKind,
+} from "@/lib/mongo/mongoCompletion";
 import { mongoDocumentsToQueryResult } from "@/lib/mongo/mongoShellCommand";
 import type { GridNewRowMeta } from "@/lib/dataGrid/gridNewRowPlacement";
 import { normalizeResultPageSize } from "@/lib/dataGrid/paginationPageSize";
@@ -95,6 +108,7 @@ import { matchesElasticsearchIndexPattern, subscribeElasticsearchIndexCleared, t
 import { TABLE_FONT_SIZE_MAX, TABLE_FONT_SIZE_MIN, useSettingsStore } from "@/stores/settingsStore";
 import { useToast } from "@/composables/useToast";
 import { copyToClipboard } from "@/lib/common/clipboard";
+import DocumentQueryCompletionMenu from "./DocumentQueryCompletionMenu.vue";
 import JsonEditNode from "./JsonEditNode.vue";
 
 import type { EditNode } from "@/types/editor";
@@ -964,6 +978,8 @@ function resizeDocumentQueryInput(el: HTMLTextAreaElement | undefined) {
 function resizeDocumentQueryInputs() {
   resizeDocumentQueryInput(filterInputRef.value);
   resizeDocumentQueryInput(sortInputRef.value);
+  // A bar that just grew a line moved the menu's anchor with it.
+  repositionOpenDocumentQueryCompletions();
 }
 
 function formatFilterInput() {
@@ -990,6 +1006,330 @@ watch([filterInput, sortInput], () => {
   void nextTick(resizeDocumentQueryInputs);
 });
 
+/* ---------------------------------------------------------------- *
+ * Filter / sort bar completion (MongoDB)
+ *
+ * The bars hold a bare query document, so they reuse the same field
+ * and operator tables as the query editor's `find({ … })` completion
+ * — a collection's field names are exactly what is too long to
+ * remember and retype here. Only MongoDB opts in: the other document
+ * stores put their own dialects in these inputs.
+ * ---------------------------------------------------------------- */
+
+type DocumentQueryCompletionTarget = "filter" | "sort";
+
+const DOCUMENT_QUERY_COMPLETION_MENU_LIMIT = 50;
+
+const documentQueryCompletionTarget = ref<DocumentQueryCompletionTarget | null>(null);
+const documentQueryCompletionItems = ref<MongoCompletionItem[]>([]);
+const documentQueryCompletionIndex = ref(0);
+const documentQueryCompletionPosition = ref<DataGridConditionSuggestionPosition>({ left: 0, top: 0, width: 0 });
+const documentQueryCompletionListboxId = `document-query-completions-${uuid()}`;
+const documentQueryCompletionEnabled = computed(() => documentStoreProvider.value.kind === "mongodb");
+const documentQueryCompletionOpen = computed(() => documentQueryCompletionTarget.value !== null && documentQueryCompletionItems.value.length > 0);
+const documentQueryCompletionActiveDescendant = computed(() => (documentQueryCompletionOpen.value ? `${documentQueryCompletionListboxId}-option-${documentQueryCompletionIndex.value}` : undefined));
+// Guards the field lookup: a keystroke that lands while a previous refresh is
+// still awaiting fields must win, and a dismiss must cancel both.
+let documentQueryCompletionRequestId = 0;
+
+function documentQueryCompletionKind(target: DocumentQueryCompletionTarget): MongoDocumentQueryKind {
+  return target === "filter" ? "filter" : "sortKeys";
+}
+
+function documentQueryCompletionInputEl(target: DocumentQueryCompletionTarget): HTMLTextAreaElement | undefined {
+  return target === "filter" ? filterInputRef.value : sortInputRef.value;
+}
+
+function documentQueryCompletionText(target: DocumentQueryCompletionTarget): string {
+  return target === "filter" ? filterInput.value : sortInput.value;
+}
+
+// Walking every loaded document is too much to redo on each keystroke — under
+// infinite scroll `documents` holds every page fetched so far — so the page's
+// fields are derived once per load and reused until the rows change.
+const documentQueryCompletionLocalFields = computed<MongoCompletionField[]>(() => (documentQueryCompletionEnabled.value ? inferMongoCompletionFields(documents.value) : []));
+
+/**
+ * Fields the collection is known to have: those visible in the loaded page,
+ * which carry the types the grid already inferred, plus the store's cached
+ * server-side sample, which also covers fields the current page happens not to
+ * contain.
+ */
+async function documentQueryCompletionFields(): Promise<MongoCompletionField[]> {
+  const byName = new Map(documentQueryCompletionLocalFields.value.map((field) => [field.name, field]));
+  let sampled: MongoCompletionField[] = [];
+  try {
+    sampled = await connectionStore.listMongoCompletionFields(props.connectionId, props.database, props.collection);
+  } catch {
+    sampled = [];
+  }
+  for (const field of sampled) if (!byName.has(field.name)) byName.set(field.name, field);
+  return [...byName.values()].sort((a, b) => a.name.localeCompare(b.name));
+}
+
+function dismissDocumentQueryCompletions() {
+  documentQueryCompletionRequestId++;
+  documentQueryCompletionTarget.value = null;
+  documentQueryCompletionItems.value = [];
+  documentQueryCompletionIndex.value = 0;
+}
+
+async function refreshDocumentQueryCompletions(target: DocumentQueryCompletionTarget, options: { force?: boolean } = {}) {
+  if (!documentQueryCompletionEnabled.value) return;
+  const text = documentQueryCompletionText(target);
+  const cursor = documentQueryCompletionInputEl(target)?.selectionStart ?? text.length;
+  const kind = documentQueryCompletionKind(target);
+
+  // Without `force` (Ctrl/Cmd+Space, or a just-accepted item that opens a new
+  // position) the menu only appears for characters that start something.
+  if (!options.force && !shouldAutoOpenMongoDocumentQueryCompletion(text, cursor, kind)) {
+    dismissDocumentQueryCompletions();
+    return;
+  }
+
+  const context = getMongoDocumentQueryCompletionContext(text, cursor, kind);
+  if (context.mode === "none") {
+    dismissDocumentQueryCompletions();
+    return;
+  }
+
+  const requestId = ++documentQueryCompletionRequestId;
+  const fields = mongoCompletionNeedsFields(context.mode) ? await documentQueryCompletionFields() : [];
+  if (requestId !== documentQueryCompletionRequestId) return;
+
+  const items = buildMongoCompletionItemsFromContext(context, { fields }).slice(0, DOCUMENT_QUERY_COMPLETION_MENU_LIMIT);
+  if (items.length === 0) {
+    dismissDocumentQueryCompletions();
+    return;
+  }
+  documentQueryCompletionTarget.value = target;
+  documentQueryCompletionItems.value = items;
+  documentQueryCompletionIndex.value = 0;
+  updateDocumentQueryCompletionPosition(target);
+}
+
+/**
+ * Anchors the menu to its input in viewport coordinates, which is what a
+ * teleported menu needs: the grid's toolbar clips both axes, so the menu cannot
+ * live next to the input in the DOM.
+ */
+function updateDocumentQueryCompletionPosition(target: DocumentQueryCompletionTarget) {
+  const input = documentQueryCompletionInputEl(target);
+  if (!input) return;
+  documentQueryCompletionPosition.value = getDataGridConditionSuggestionPosition(input.getBoundingClientRect(), {
+    viewportWidth: window.innerWidth,
+    minWidth: 240,
+    maxWidth: 460,
+  });
+}
+
+// Teleported out of the input's box, the menu cannot follow it on its own: the
+// toolbar scrolls horizontally and the window resizes without the input ever
+// being touched.
+function repositionOpenDocumentQueryCompletions() {
+  const target = documentQueryCompletionTarget.value;
+  if (target) updateDocumentQueryCompletionPosition(target);
+}
+
+watch(documentQueryCompletionOpen, (open) => {
+  if (open) {
+    window.addEventListener("scroll", repositionOpenDocumentQueryCompletions, true);
+    window.addEventListener("resize", repositionOpenDocumentQueryCompletions);
+  } else {
+    window.removeEventListener("scroll", repositionOpenDocumentQueryCompletions, true);
+    window.removeEventListener("resize", repositionOpenDocumentQueryCompletions);
+  }
+});
+
+function selectDocumentQueryCompletion(index: number) {
+  if (index < 0 || index >= documentQueryCompletionItems.value.length) return;
+  documentQueryCompletionIndex.value = index;
+  void nextTick(() => {
+    const listbox = document.getElementById(documentQueryCompletionListboxId);
+    const option = document.getElementById(`${documentQueryCompletionListboxId}-option-${index}`);
+    if (!listbox || !option) return;
+    const listboxRect = listbox.getBoundingClientRect();
+    const optionRect = option.getBoundingClientRect();
+    if (optionRect.top < listboxRect.top) listbox.scrollTop -= listboxRect.top - optionRect.top;
+    else if (optionRect.bottom > listboxRect.bottom) listbox.scrollTop += optionRect.bottom - listboxRect.bottom;
+  });
+}
+
+function moveDocumentQueryCompletionSelection(direction: 1 | -1): boolean {
+  if (!documentQueryCompletionOpen.value) return false;
+  const count = documentQueryCompletionItems.value.length;
+  const next = Math.min(Math.max(documentQueryCompletionIndex.value + direction, 0), count - 1);
+  if (next !== documentQueryCompletionIndex.value) selectDocumentQueryCompletion(next);
+  return true;
+}
+
+function documentQueryCompletionInsertion(index = documentQueryCompletionIndex.value) {
+  const target = documentQueryCompletionTarget.value;
+  const item = documentQueryCompletionItems.value[index];
+  if (!target || !item) return null;
+
+  const input = documentQueryCompletionInputEl(target);
+  const text = documentQueryCompletionText(target);
+  const cursor = input?.selectionStart ?? text.length;
+  const context = getMongoDocumentQueryCompletionContext(text, cursor, documentQueryCompletionKind(target));
+  if (context.mode === "none") return null;
+
+  // A quoted key completion writes both of its quotes, so the closing quote the
+  // input already holds has to go with the prefix it belongs to.
+  const to = Math.min((input?.selectionEnd ?? text.length) + (item.replaceClosingQuote ? 1 : 0), text.length);
+  const insertion = plainMongoCompletionInsertion(item.apply ?? item.label, text.slice(to));
+  return { target, text, from: context.from, to, insertion };
+}
+
+function acceptDocumentQueryCompletion(index = documentQueryCompletionIndex.value): boolean {
+  const completion = documentQueryCompletionInsertion(index);
+  if (!completion) return false;
+
+  const { target, text, from, to, insertion } = completion;
+  const next = `${text.slice(0, from)}${insertion.text}${text.slice(to)}`;
+  if (target === "filter") filterInput.value = next;
+  else sortInput.value = next;
+  dismissDocumentQueryCompletions();
+
+  void nextTick(() => {
+    const input = documentQueryCompletionInputEl(target);
+    if (!input) return;
+    input.focus();
+    input.setSelectionRange(from + insertion.selectionStart, from + insertion.selectionEnd);
+    // A field completion ends at `field: `, an operator at its value — both are
+    // fresh positions with their own suggestions, so open the menu again.
+    void refreshDocumentQueryCompletions(target, { force: true });
+  });
+  return true;
+}
+
+/** True when accepting would not change the text, so Enter should run the query instead. */
+function documentQueryCompletionMatchesInput(): boolean {
+  const completion = documentQueryCompletionInsertion();
+  if (!completion) return false;
+  return completion.text.slice(completion.from, completion.to) === completion.insertion.text;
+}
+
+/**
+ * Opens the document around the first character typed into an empty bar, so
+ * `d` becomes `{d}` with the caret left between the braces.
+ *
+ * The bars hold a bare document and a field name only reads as a key once its
+ * braces exist, so typing straight into an empty bar used to land in a position
+ * that classifies as nothing and suggested nothing — the very case #9427
+ * reports. Nothing is lost by writing the braces: an unbraced bar never parses
+ * as a filter either, so that text was a dead query, not a shorter spelling of
+ * one.
+ *
+ * Only a lone character that could start a key qualifies. A paste arrives whole
+ * and usually brings its own braces, and a typed `{` is the user opening the
+ * document themselves — which already suggests.
+ *
+ * The edit has to be an insertion. Backspacing `ab` down to `a` leaves exactly
+ * the same one character and caret as typing `a` into an empty bar, and writing
+ * braces around text the user is in the middle of deleting would hand them two
+ * more characters to delete.
+ */
+function openDocumentQueryDocument(event: InputEvent, target: DocumentQueryCompletionTarget): boolean {
+  if (!documentQueryCompletionEnabled.value) return false;
+  if (!event.inputType?.startsWith("insert")) return false;
+  const text = documentQueryCompletionText(target);
+  const prefix = readMongoPropertyPrefix(text, text.length);
+  if ([...text].length !== 1 || !/^[$_"'\p{L}\p{N}]$/u.test(text) || prefix.from !== 0 || prefix.prefix !== text) return false;
+  if (documentQueryCompletionInputEl(target)?.selectionStart !== text.length) return false;
+
+  if (target === "filter") filterInput.value = `{${text}}`;
+  else sortInput.value = `{${text}}`;
+
+  // Rewriting the model moves the caret to the end, past the `}` we just added,
+  // where there is nothing to complete. Put it back inside before asking.
+  void nextTick(() => {
+    documentQueryCompletionInputEl(target)?.setSelectionRange(text.length + 1, text.length + 1);
+    void refreshDocumentQueryCompletions(target);
+  });
+  return true;
+}
+
+function onDocumentQueryInput(event: Event, target: DocumentQueryCompletionTarget) {
+  // `v-model` holds off on the model until the composition is confirmed, so a
+  // mid-composition refresh would suggest against the text as it was before the
+  // IME opened. Vue re-dispatches `input` once it commits, which is when the
+  // suggestions are worth computing.
+  if ((event as InputEvent).isComposing) return;
+  if (openDocumentQueryDocument(event as InputEvent, target)) return;
+  void refreshDocumentQueryCompletions(target);
+}
+
+/**
+ * Dismissing also cancels whatever refresh is in flight, which is the point:
+ * the target is only set once `documentQueryCompletionFields` has resolved, so
+ * a bar blurred during that first (uncached) backend round trip would otherwise
+ * open its menu afterwards, over a bar that no longer has focus. Nothing else
+ * would take it down — the menu is teleported to `body` and there is no
+ * outside-click handler.
+ */
+function onDocumentQueryBlur(target: DocumentQueryCompletionTarget) {
+  if (documentQueryCompletionTarget.value === null || documentQueryCompletionTarget.value === target) dismissDocumentQueryCompletions();
+}
+
+/**
+ * The suggestions describe the position the caret was in when they were built,
+ * so a caret moved without an edit leaves them describing somewhere else:
+ * accepting one then splices a stale item at a freshly computed offset and
+ * garbles the text. Moving the caret closes the menu instead.
+ */
+function onDocumentQueryCaretMove(target: DocumentQueryCompletionTarget) {
+  if (documentQueryCompletionTarget.value === target) dismissDocumentQueryCompletions();
+}
+
+function onDocumentQueryKeydown(event: KeyboardEvent, target: DocumentQueryCompletionTarget) {
+  if (event.isComposing) return;
+
+  if (documentQueryCompletionEnabled.value) {
+    if ((event.ctrlKey || event.metaKey) && event.code === "Space") {
+      event.preventDefault();
+      void refreshDocumentQueryCompletions(target, { force: true });
+      return;
+    }
+    if (event.key === "Escape" && documentQueryCompletionOpen.value) {
+      event.preventDefault();
+      dismissDocumentQueryCompletions();
+      return;
+    }
+    // These move the caret rather than the selection, so they leave the open
+    // suggestions describing a position the caret has left. The key still does
+    // its normal job — only the menu goes.
+    if (event.key === "ArrowLeft" || event.key === "ArrowRight" || event.key === "Home" || event.key === "End") {
+      onDocumentQueryCaretMove(target);
+      return;
+    }
+    if (event.key === "ArrowDown" && moveDocumentQueryCompletionSelection(1)) {
+      event.preventDefault();
+      return;
+    }
+    if (event.key === "ArrowUp" && moveDocumentQueryCompletionSelection(-1)) {
+      event.preventDefault();
+      return;
+    }
+    if (event.key === "Tab" && !event.shiftKey && documentQueryCompletionOpen.value && acceptDocumentQueryCompletion()) {
+      event.preventDefault();
+      return;
+    }
+    // Enter takes the highlighted suggestion first; a second Enter runs the query.
+    if (event.key === "Enter" && !event.ctrlKey && !event.metaKey && !event.altKey && !event.shiftKey && documentQueryCompletionOpen.value && !documentQueryCompletionMatchesInput() && acceptDocumentQueryCompletion()) {
+      event.preventDefault();
+      return;
+    }
+  }
+
+  if (event.key !== "Enter") return;
+  const plainEnter = !event.ctrlKey && !event.metaKey && !event.altKey && !event.shiftKey;
+  if (!plainEnter && !((event.ctrlKey || event.metaKey) && !event.altKey && !event.shiftKey)) return;
+  event.preventDefault();
+  dismissDocumentQueryCompletions();
+  applyFilter();
+}
+
 const documentQueryPreview = computed(() => {
   let filter = "{}";
   try {
@@ -2288,6 +2628,9 @@ onMounted(async () => {
 });
 onBeforeUnmount(() => {
   persistDocumentBrowserState({ includeData: true });
+  // The open/close watcher cannot run on unmount, so drop the menu's listeners here.
+  window.removeEventListener("scroll", repositionOpenDocumentQueryCompletions, true);
+  window.removeEventListener("resize", repositionOpenDocumentQueryCompletions);
   window.removeEventListener("pointerdown", handleDocumentBrowserPointerDown, true);
   unsubscribeElasticsearchIndexCleared?.();
   unsubscribeElasticsearchIndexCleared = undefined;
@@ -2799,9 +3142,24 @@ defineExpose({ focusSearch });
               rows="1"
               class="document-query-input flex-1 min-w-0 text-xs bg-transparent outline-none placeholder:text-muted-foreground/60 font-mono"
               placeholder="{}"
-              @keydown.enter.exact.prevent="applyFilter"
-              @keydown.ctrl.enter.prevent="applyFilter"
-              @keydown.meta.enter.prevent="applyFilter"
+              :aria-autocomplete="documentQueryCompletionEnabled ? 'list' : undefined"
+              :aria-controls="documentQueryCompletionTarget === 'filter' ? documentQueryCompletionListboxId : undefined"
+              :aria-activedescendant="documentQueryCompletionTarget === 'filter' ? documentQueryCompletionActiveDescendant : undefined"
+              :aria-expanded="documentQueryCompletionEnabled ? documentQueryCompletionTarget === 'filter' : undefined"
+              @blur="onDocumentQueryBlur('filter')"
+              @click="onDocumentQueryCaretMove('filter')"
+              @input="onDocumentQueryInput($event, 'filter')"
+              @keydown="onDocumentQueryKeydown($event, 'filter')"
+            />
+            <DocumentQueryCompletionMenu
+              v-if="documentQueryCompletionOpen && documentQueryCompletionTarget === 'filter'"
+              :items="documentQueryCompletionItems"
+              :selected-index="documentQueryCompletionIndex"
+              :listbox-id="documentQueryCompletionListboxId"
+              :label="documentStoreLabels.filterInputLabel"
+              :position="documentQueryCompletionPosition"
+              @select="selectDocumentQueryCompletion"
+              @accept="acceptDocumentQueryCompletion"
             />
             <button v-if="filterInput.trim()" type="button" class="flex h-5 shrink-0 items-center text-muted-foreground hover:text-foreground" title="Format JSON" aria-label="Format JSON" @click="formatFilterInput">
               <Braces class="w-3 h-3" />
@@ -2838,9 +3196,24 @@ defineExpose({ focusSearch });
               rows="1"
               class="document-query-input flex-1 min-w-0 text-xs bg-transparent outline-none placeholder:text-muted-foreground/60 font-mono"
               placeholder="{}"
-              @keydown.enter.exact.prevent="applyFilter"
-              @keydown.ctrl.enter.prevent="applyFilter"
-              @keydown.meta.enter.prevent="applyFilter"
+              :aria-autocomplete="documentQueryCompletionEnabled ? 'list' : undefined"
+              :aria-controls="documentQueryCompletionTarget === 'sort' ? documentQueryCompletionListboxId : undefined"
+              :aria-activedescendant="documentQueryCompletionTarget === 'sort' ? documentQueryCompletionActiveDescendant : undefined"
+              :aria-expanded="documentQueryCompletionEnabled ? documentQueryCompletionTarget === 'sort' : undefined"
+              @blur="onDocumentQueryBlur('sort')"
+              @click="onDocumentQueryCaretMove('sort')"
+              @input="onDocumentQueryInput($event, 'sort')"
+              @keydown="onDocumentQueryKeydown($event, 'sort')"
+            />
+            <DocumentQueryCompletionMenu
+              v-if="documentQueryCompletionOpen && documentQueryCompletionTarget === 'sort'"
+              :items="documentQueryCompletionItems"
+              :selected-index="documentQueryCompletionIndex"
+              :listbox-id="documentQueryCompletionListboxId"
+              :label="documentStoreLabels.sortInputLabel"
+              :position="documentQueryCompletionPosition"
+              @select="selectDocumentQueryCompletion"
+              @accept="acceptDocumentQueryCompletion"
             />
             <button v-if="sortInput.trim()" type="button" class="flex h-5 shrink-0 items-center text-muted-foreground hover:text-foreground" title="Format JSON" aria-label="Format JSON" @click="formatSortInput">
               <Braces class="w-3 h-3" />
diff --git a/apps/desktop/src/components/document/DocumentQueryCompletionMenu.vue b/apps/desktop/src/components/document/DocumentQueryCompletionMenu.vue
new file mode 100644
index 0000000000..bf88a9ebab
--- /dev/null
+++ b/apps/desktop/src/components/document/DocumentQueryCompletionMenu.vue
@@ -0,0 +1,81 @@
+<script setup lang="ts">
+import type { CSSProperties } from "vue";
+import { computed } from "vue";
+import type { DataGridConditionSuggestionPosition } from "@/lib/dataGrid/dataGridConditionSuggestionPosition";
+import type { MongoCompletionItem } from "@/lib/mongo/mongoCompletion";
+
+defineOptions({ name: "DocumentQueryCompletionMenu" });
+
+const props = defineProps<{
+  items: MongoCompletionItem[];
+  selectedIndex: number;
+  listboxId: string;
+  label: string;
+  /** Viewport coordinates of the input this menu hangs under. */
+  position: DataGridConditionSuggestionPosition;
+}>();
+
+const emit = defineEmits<{
+  (e: "select", index: number): void;
+  (e: "accept", index: number): void;
+}>();
+
+/** Mirrors the query editor's completion icons: fields read as columns, operators as keywords. */
+const TYPE_GLYPH: Record<MongoCompletionItem["type"], string> = {
+  column: "#",
+  function: "ƒ",
+  keyword: "$",
+  snippet: "{}",
+  table: "▤",
+};
+
+const style = computed<CSSProperties>(() => ({
+  left: `${props.position.left}px`,
+  top: `${props.position.top}px`,
+  width: `${props.position.width}px`,
+}));
+
+function glyph(item: MongoCompletionItem): string {
+  return TYPE_GLYPH[item.type] ?? "#";
+}
+
+function isSelected(index: number): boolean {
+  return props.selectedIndex === index;
+}
+</script>
+
+<template>
+  <!--
+    The grid's toolbar clips both axes and is only 32px tall, so a dropdown
+    positioned inside it would never be visible. Teleporting to fixed viewport
+    coordinates is what the grid's own condition suggestions do.
+  -->
+  <Teleport to="body">
+    <!--
+      The container takes the same `mousedown.prevent` as its options: the list
+      scrolls, and a press on its scrollbar or padding would otherwise blur the
+      input and unmount the menu mid-drag, leaving everything below the fold
+      reachable by keyboard only.
+    -->
+    <div :id="listboxId" role="listbox" :aria-label="label" class="fixed z-[90] max-h-64 overflow-y-auto overflow-x-hidden rounded-md border bg-popover py-1 text-popover-foreground shadow-md" :style="style" @mousedown.prevent>
+      <button
+        v-for="(item, index) in items"
+        :id="`${listboxId}-option-${index}`"
+        :key="`${item.type}:${item.label}:${index}`"
+        type="button"
+        role="option"
+        :aria-selected="isSelected(index)"
+        :aria-description="item.info"
+        class="flex w-full items-center gap-2 px-2 py-1 text-left text-xs"
+        :class="isSelected(index) ? 'bg-accent text-accent-foreground' : 'hover:bg-accent/50'"
+        @pointerenter="emit('select', index)"
+        @mousedown.prevent
+        @click.stop="emit('accept', index)"
+      >
+        <span class="w-3 shrink-0 text-center font-mono text-[10px] text-muted-foreground">{{ glyph(item) }}</span>
+        <span class="min-w-0 flex-1 truncate font-mono">{{ item.label }}</span>
+        <span v-if="item.detail" class="max-w-[55%] shrink-0 truncate text-[11px] text-muted-foreground">{{ item.detail }}</span>
+      </button>
+    </div>
+  </Teleport>
+</template>
diff --git a/apps/desktop/src/components/document/__tests__/DocumentBrowserFieldSearch.spec.ts b/apps/desktop/src/components/document/__tests__/DocumentBrowserFieldSearch.spec.ts
index 4fda5d6d52..d8d09889f8 100644
--- a/apps/desktop/src/components/document/__tests__/DocumentBrowserFieldSearch.spec.ts
+++ b/apps/desktop/src/components/document/__tests__/DocumentBrowserFieldSearch.spec.ts
@@ -280,6 +280,11 @@ async function flushUi() {
   for (let index = 0; index < 4; index++) {
     await Promise.resolve();
     await nextTick();
+    // The mount chain (ensureConnected → load → render) spans more than a fixed
+    // number of microtask rounds once a real timer is in it, and DocumentBrowser
+    // renders from state those steps produce. Yielding to the macrotask queue
+    // lets each of them settle instead of leaving the component half-loaded.
+    await new Promise((resolve) => setTimeout(resolve, 0));
   }
 }
 
diff --git a/apps/desktop/src/components/document/__tests__/DocumentBrowserQueryCompletion.spec.ts b/apps/desktop/src/components/document/__tests__/DocumentBrowserQueryCompletion.spec.ts
new file mode 100644
index 0000000000..ce832babba
--- /dev/null
+++ b/apps/desktop/src/components/document/__tests__/DocumentBrowserQueryCompletion.spec.ts
@@ -0,0 +1,750 @@
+// @vitest-environment happy-dom
+
+import { createApp, defineComponent, h, nextTick, type App } from "vue";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+const backend = vi.hoisted(() => ({
+  documentFindDocuments: vi.fn(),
+  documentCountDocuments: vi.fn(),
+  getColumns: vi.fn(),
+  cancelQuery: vi.fn(),
+  ensureConnected: vi.fn(),
+  listMongoCompletionFields: vi.fn(),
+}));
+
+const settings = vi.hoisted(() => ({
+  editorSettings: {
+    pageSize: 50,
+    mongoViewMode: "table" as "document" | "table",
+    columnWidthDensity: "standard" as "compact" | "standard" | "comfortable",
+    dataGridRenderMode: "canvas" as "canvas" | "dom",
+    tableFontFamily: "system-ui",
+    tableFontSize: 12,
+    numericColumnRightAlign: true,
+    confirmDangerousSqlExecution: true,
+    exportBatchSize: 2,
+    exportRowLimitEnabled: false,
+    exportRowLimit: 100_000,
+  },
+  updateEditorSettings: vi.fn(),
+}));
+
+vi.mock("vue-i18n", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("vue-i18n")>()),
+  useI18n: () => ({ t: (key: string) => key }),
+}));
+
+vi.mock("@/lib/backend/api", () => ({
+  getColumns: backend.getColumns,
+  documentFindDocuments: backend.documentFindDocuments,
+  documentCountDocuments: backend.documentCountDocuments,
+  dynamodbDescribeTable: vi.fn(),
+  cancelQuery: backend.cancelQuery,
+  documentInsertDocument: vi.fn(),
+  documentUpdateDocument: vi.fn(),
+  documentDeleteDocument: vi.fn(),
+  documentSaveMeilisearchBatch: vi.fn(),
+}));
+
+vi.mock("@/stores/connectionStore", () => ({
+  useConnectionStore: () => ({
+    ensureConnected: backend.ensureConnected,
+    listMongoCompletionFields: backend.listMongoCompletionFields,
+  }),
+}));
+
+vi.mock("@/stores/settingsStore", () => ({
+  TABLE_FONT_SIZE_MIN: 8,
+  TABLE_FONT_SIZE_MAX: 16,
+  useSettingsStore: () => settings,
+}));
+
+vi.mock("@/components/grid/DataGrid.vue", () => ({
+  default: defineComponent({
+    name: "DataGridStub",
+    inheritAttrs: false,
+    props: { result: { type: Object, required: true } },
+    setup(_, { expose, slots }) {
+      expose({
+        visibleColumnCount: 0,
+        displayableColumnCount: 0,
+        hiddenColumnCount: 0,
+        orderedColumnLayoutOptions: [],
+        filteredColumnLayoutOptions: () => [],
+        toggleColumnVisibility: vi.fn(),
+        showAllColumns: vi.fn(),
+        invertColumnVisibility: vi.fn(),
+        hasCustomColumnOrder: false,
+        moveDisplayableColumn: vi.fn(),
+        resetColumnOrder: vi.fn(),
+        nullColumnsHidden: false,
+        canToggleAllNullColumns: false,
+        allNullColumnCount: 0,
+        toggleAllNullColumns: vi.fn(),
+        multiRowTranspose: false,
+        setMultiRowTranspose: vi.fn(),
+      });
+      return () =>
+        h("div", { "data-testid": "data-grid" }, [
+          slots["search-bar"]?.({
+            localFilterCount: 0,
+            hasLocalColumnFilters: false,
+            localFilterSummaries: [],
+            clearLocalFilter: vi.fn(),
+          }),
+        ]);
+    },
+  }),
+}));
+
+vi.mock("@/components/redis/RedisJsonEditor.vue", async () => {
+  const { defineComponent: define, h: hh } = await import("vue");
+  return {
+    default: define({
+      props: { modelValue: { type: String, required: true } },
+      setup(props) {
+        return () => hh("div", {}, props.modelValue);
+      },
+    }),
+  };
+});
+
+vi.mock("@/components/ui/popover", async () => {
+  const { defineComponent: define, h: hh } = await import("vue");
+  const passthrough = (name: string) =>
+    define({
+      name,
+      setup(_, { slots }) {
+        return () => hh("div", slots.default?.());
+      },
+    });
+  return { Popover: passthrough("PopoverStub"), PopoverTrigger: passthrough("PopoverTriggerStub"), PopoverContent: passthrough("PopoverContentStub") };
+});
+
+vi.mock("@/components/ui/select", async () => {
+  const { defineComponent: define, h: hh } = await import("vue");
+  const passthrough = (name: string) =>
+    define({
+      name,
+      setup(_, { slots }) {
+        return () => hh("div", slots.default?.());
+      },
+    });
+  return { Select: passthrough("SelectStub"), SelectContent: passthrough("SelectContentStub"), SelectItem: passthrough("SelectItemStub"), SelectTrigger: passthrough("SelectTriggerStub"), SelectValue: passthrough("SelectValueStub") };
+});
+
+import DocumentBrowser from "@/components/document/DocumentBrowser.vue";
+
+let app: App<Element> | null = null;
+let root: HTMLDivElement | null = null;
+
+async function flushUi() {
+  for (let index = 0; index < 4; index++) {
+    await Promise.resolve();
+    await nextTick();
+    await new Promise((resolve) => setTimeout(resolve, 0));
+  }
+}
+
+async function mountBrowser(databaseType: "mongodb" | "elasticsearch" = "mongodb") {
+  app = createApp(DocumentBrowser, {
+    connectionId: databaseType === "mongodb" ? "mongo-1" : "es-1",
+    database: "shop",
+    collection: "orders",
+    databaseType,
+  });
+  app.mount(root!);
+  await flushUi();
+}
+
+/** [filter, sort] — the two query bars rendered in the grid's search slot. */
+function queryInputs(): HTMLTextAreaElement[] {
+  return [...root!.querySelectorAll<HTMLTextAreaElement>("textarea.document-query-input")];
+}
+
+/** `inputType` matters: the bars only open a document around an *inserted* character. */
+async function typeInto(input: HTMLTextAreaElement, text: string, caret = text.length, inputType = "insertText") {
+  input.value = text;
+  input.setSelectionRange(caret, caret);
+  input.dispatchEvent(new InputEvent("input", { bubbles: true, inputType }));
+  await flushUi();
+}
+
+/** Moves the caret the way a mouse click does — no edit, so no `input` event. */
+async function clickCaretTo(input: HTMLTextAreaElement, offset: number) {
+  input.setSelectionRange(offset, offset);
+  input.dispatchEvent(new Event("click", { bubbles: true }));
+  await flushUi();
+}
+
+function pressKey(input: HTMLTextAreaElement, key: string, init: KeyboardEventInit = {}) {
+  const event = new KeyboardEvent("keydown", { key, bubbles: true, cancelable: true, ...init });
+  input.dispatchEvent(event);
+  return event;
+}
+
+/**
+ * The menu is teleported out of the grid toolbar (which clips both axes), so it
+ * is only ever found on `document.body` — never under the mounted tree.
+ */
+function menu(): HTMLElement | null {
+  return document.body.querySelector<HTMLElement>('[role="listbox"]');
+}
+
+function menuOptions(): string[] {
+  return [...document.body.querySelectorAll<HTMLElement>('[role="listbox"] [role="option"] span:nth-child(2)')].map((option) => option.textContent ?? "");
+}
+
+function menuOpen(): boolean {
+  return menu() !== null;
+}
+
+function selectedOption(): string | null {
+  const option = document.body.querySelector<HTMLElement>('[role="option"][aria-selected="true"]');
+  return option?.querySelector("span:nth-child(2)")?.textContent ?? null;
+}
+
+beforeEach(() => {
+  vi.stubGlobal("localStorage", {
+    getItem: () => null,
+    setItem: () => undefined,
+    removeItem: () => undefined,
+  });
+  for (const mock of Object.values(backend)) mock.mockReset();
+  backend.ensureConnected.mockResolvedValue(undefined);
+  backend.documentCountDocuments.mockResolvedValue(0);
+  backend.getColumns.mockResolvedValue([]);
+  backend.documentFindDocuments.mockResolvedValue({
+    documents: [
+      { _id: "1", customerShippingAddress: "Beijing", createdAt: "2026-01-01" },
+      { _id: "2", customerShippingAddress: "Shanghai", createdAt: "2026-01-02" },
+    ],
+    raw_documents: [],
+    total: 2,
+    total_is_exact: true,
+  });
+  // The store's cached sample also knows a field the loaded page happens not to show.
+  backend.listMongoCompletionFields.mockResolvedValue([
+    { name: "customerShippingAddress", type: "string" },
+    { name: "discountCode", type: "string" },
+    { name: "中文字段", type: "string" },
+    { name: "客户 名", type: "string" },
+  ]);
+
+  root = document.createElement("div");
+  document.body.appendChild(root);
+});
+
+afterEach(() => {
+  app?.unmount();
+  root?.remove();
+  app = null;
+  root = null;
+  vi.unstubAllGlobals();
+});
+
+describe("DocumentBrowser MongoDB query bar completion (issue #9427)", () => {
+  it("suggests the collection's fields as soon as the filter document is opened", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{");
+
+    expect(menuOpen()).toBe(true);
+    // Fields from the loaded page and from the store's sample, both offered.
+    expect(menuOptions()).toEqual(expect.arrayContaining(["_id", "createdAt", "customerShippingAddress", "discountCode"]));
+  });
+
+  it("escapes the grid toolbar's clipping by positioning itself on the body", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{");
+
+    // Anywhere inside the mounted tree the toolbar's `overflow-clip` would hide it.
+    expect(root!.querySelector('[role="listbox"]')).toBeNull();
+    expect(menu()!.parentElement).toBe(document.body);
+    expect(menu()!.className).toContain("fixed");
+    expect(menu()!.style.width).not.toBe("");
+    expect(menu()!.style.top).not.toBe("");
+  });
+
+  it("narrows the suggestions to the typed prefix", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{ customerS");
+
+    expect(menuOptions()).toEqual(["customerShippingAddress"]);
+  });
+
+  it("keeps completion open after an IME commits a Unicode first character", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    filter!.dispatchEvent(new CompositionEvent("compositionstart", { bubbles: true }));
+    filter!.value = "中";
+    filter!.setSelectionRange(1, 1);
+    filter!.dispatchEvent(new InputEvent("input", { bubbles: true, inputType: "insertCompositionText", isComposing: true }));
+    await flushUi();
+    expect(menuOpen()).toBe(false);
+
+    filter!.dispatchEvent(new CompositionEvent("compositionend", { bubbles: true }));
+    await typeInto(filter!, "中", 1, "insertCompositionText");
+
+    expect(filter!.value).toBe("{中}");
+    expect(menuOptions()).toEqual(["中文字段"]);
+
+    pressKey(filter!, "Tab");
+    await flushUi();
+
+    expect(filter!.value).toBe('{"中文字段": }');
+
+    await typeInto(filter!, '{"中文字段": 1 }');
+    pressKey(filter!, "Enter");
+    await flushUi();
+    expect(backend.documentFindDocuments.mock.calls.at(-1)?.[5]).toBe('{"中文字段":1}');
+  });
+
+  it("replaces a quoted field prefix containing spaces", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, '{ "客户 名');
+    expect(menuOptions()).toEqual(["客户 名"]);
+
+    pressKey(filter!, "Tab");
+    await flushUi();
+
+    expect(filter!.value).toBe('{ "客户 名": ');
+  });
+
+  it("completes the highlighted field on Tab and leaves the caret in value position", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, "{ customerS");
+
+    const event = pressKey(filter!, "Tab");
+    await flushUi();
+
+    expect(event.defaultPrevented).toBe(true);
+    expect(filter!.value).toBe("{ customerShippingAddress: ");
+    expect(filter!.selectionStart).toBe("{ customerShippingAddress: ".length);
+  });
+
+  it("moves through the suggestions with the arrow keys", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, "{ c");
+
+    const first = selectedOption();
+    pressKey(filter!, "ArrowDown");
+    await flushUi();
+    const second = selectedOption();
+
+    expect(second).not.toBe(first);
+    expect(menuOptions()).toContain(second);
+
+    pressKey(filter!, "ArrowUp");
+    await flushUi();
+    expect(selectedOption()).toBe(first);
+  });
+
+  it("takes the suggestion on the first Enter and runs the query on the next", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, "{ createdA");
+    const callsBefore = backend.documentFindDocuments.mock.calls.length;
+
+    pressKey(filter!, "Enter");
+    await flushUi();
+
+    expect(filter!.value).toBe("{ createdAt: ");
+    expect(backend.documentFindDocuments.mock.calls.length).toBe(callsBefore);
+
+    await typeInto(filter!, '{ createdAt: "2026-01-01" }');
+    pressKey(filter!, "Enter");
+    await flushUi();
+
+    expect(backend.documentFindDocuments.mock.calls.length).toBeGreaterThan(callsBefore);
+    expect(backend.documentFindDocuments.mock.calls.at(-1)?.[5]).toBe('{"createdAt":"2026-01-01"}');
+  });
+
+  it("closes the menu on Escape and lets the next Enter run the query unchanged", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    // Caret inside the already-typed key, so the menu is open over a document
+    // that is otherwise complete and runnable.
+    await typeInto(filter!, '{ "createdAt": 1 }', '{ "createdAt'.length);
+    expect(menuOpen()).toBe(true);
+    const callsBefore = backend.documentFindDocuments.mock.calls.length;
+
+    pressKey(filter!, "Escape");
+    await flushUi();
+    expect(menuOpen()).toBe(false);
+
+    pressKey(filter!, "Enter");
+    await flushUi();
+    expect(filter!.value).toBe('{ "createdAt": 1 }');
+    expect(backend.documentFindDocuments.mock.calls.length).toBeGreaterThan(callsBefore);
+    expect(backend.documentFindDocuments.mock.calls.at(-1)?.[5]).toBe('{"createdAt":1}');
+  });
+
+  it("runs the query on Enter when the highlighted suggestion is what is already typed", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, '{ "createdAt": 1 }', '{ "createdAt'.length);
+    expect(selectedOption()).toBe("createdAt");
+    const callsBefore = backend.documentFindDocuments.mock.calls.length;
+
+    pressKey(filter!, "Enter");
+    await flushUi();
+
+    // Accepting would retype the same key, so Enter has nothing to take and the
+    // query runs instead — otherwise Enter could never submit this filter.
+    expect(filter!.value).toBe('{ "createdAt": 1 }');
+    expect(backend.documentFindDocuments.mock.calls.length).toBeGreaterThan(callsBefore);
+  });
+
+  it("replaces a quoted key in place without doubling its closing quote", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, '{ "customerS": 1 }', '{ "customerS'.length);
+
+    pressKey(filter!, "Tab");
+    await flushUi();
+
+    expect(filter!.value).toBe('{ "customerShippingAddress": 1 }');
+  });
+
+  it("suggests query operators inside a field constraint", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{ createdAt: { $g");
+
+    expect(menuOptions()).toEqual(expect.arrayContaining(["$gt", "$gte"]));
+  });
+
+  it("expands an operator snippet without leaving its editor placeholder behind", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, "{ createdAt: { $i");
+    while (selectedOption() !== "$in") {
+      const moved = pressKey(filter!, "ArrowDown");
+      await flushUi();
+      expect(moved.defaultPrevented, "ran out of suggestions before reaching $in").toBe(true);
+    }
+
+    pressKey(filter!, "Tab");
+    await flushUi();
+
+    expect(filter!.value).toBe("{ createdAt: { $in: []");
+    expect(filter!.selectionStart).toBe("{ createdAt: { $in: [".length);
+  });
+
+  it("completes field names in the sort bar without offering query operators", async () => {
+    await mountBrowser();
+    const [, sort] = queryInputs();
+
+    await typeInto(sort!, "{ c");
+
+    expect(menuOptions()).toEqual(expect.arrayContaining(["createdAt", "customerShippingAddress"]));
+    expect(menuOptions()).not.toEqual(expect.arrayContaining(["$and", "$or"]));
+
+    pressKey(sort!, "Tab");
+    await flushUi();
+    expect(sort!.value).toBe("{ createdAt: ");
+  });
+
+  it("keeps Shift+Enter for a newline and Ctrl+Enter for running the query", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, '{ "createdAt": 1 }');
+    const callsBefore = backend.documentFindDocuments.mock.calls.length;
+
+    const shiftEnter = pressKey(filter!, "Enter", { shiftKey: true });
+    await flushUi();
+    expect(shiftEnter.defaultPrevented).toBe(false);
+    expect(backend.documentFindDocuments.mock.calls.length).toBe(callsBefore);
+
+    const ctrlEnter = pressKey(filter!, "Enter", { ctrlKey: true });
+    await flushUi();
+    expect(ctrlEnter.defaultPrevented).toBe(true);
+    expect(backend.documentFindDocuments.mock.calls.length).toBeGreaterThan(callsBefore);
+  });
+
+  it("stays closed while an IME composition is still unconfirmed", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    // A committed key, then dismissed — so any menu that appears next can only
+    // have come from the composition. Replacing that key with IME text leaves
+    // the caret inside the stale model text, which is where a refresh would
+    // wrongly find something to say.
+    await typeInto(filter!, "{ createdAt");
+    pressKey(filter!, "Escape");
+    await flushUi();
+    expect(menuOpen()).toBe(false);
+
+    // v-model withholds the model until the IME commits, so a refresh here
+    // would suggest against "{ createdAt" while the user is typing 收货地址.
+    filter!.dispatchEvent(new CompositionEvent("compositionstart", { bubbles: true }));
+    filter!.value = "{ 收";
+    filter!.setSelectionRange(4, 4);
+    filter!.dispatchEvent(new InputEvent("input", { bubbles: true, isComposing: true }));
+    await flushUi();
+    expect(menuOpen()).toBe(false);
+
+    // Vue re-dispatches `input` when the composition commits, and that edit is
+    // worth suggesting against.
+    filter!.value = "{ c";
+    filter!.setSelectionRange(3, 3);
+    filter!.dispatchEvent(new CompositionEvent("compositionend", { bubbles: true }));
+    await flushUi();
+    expect(menuOpen()).toBe(true);
+    expect(menuOptions()).toEqual(expect.arrayContaining(["createdAt", "customerShippingAddress"]));
+  });
+
+  it("ignores an IME confirmation Enter", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+    await typeInto(filter!, '{ "createdAt": 1 }');
+    const callsBefore = backend.documentFindDocuments.mock.calls.length;
+
+    pressKey(filter!, "Enter", { isComposing: true });
+    await flushUi();
+
+    expect(backend.documentFindDocuments.mock.calls.length).toBe(callsBefore);
+  });
+
+  it("says nothing once the filter document is complete", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, '{ createdAt: "2026-01-01" }');
+
+    expect(menuOpen()).toBe(false);
+  });
+
+  it("leaves the other document stores' query bars alone", async () => {
+    await mountBrowser("elasticsearch");
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{ c");
+
+    expect(menuOpen()).toBe(false);
+    expect(backend.listMongoCompletionFields).not.toHaveBeenCalled();
+  });
+});
+
+describe("DocumentBrowser MongoDB query bar completion lifecycle", () => {
+  it("does not open a menu on a bar that lost focus while the fields were loading", async () => {
+    // The first keystroke in a collection waits on a real backend sample, and
+    // the target is only set once it resolves — so a blur before that has to
+    // cancel the refresh, not just close a menu that is not open yet.
+    let releaseFields!: (fields: Array<{ name: string; type: string }>) => void;
+    backend.listMongoCompletionFields.mockReturnValue(new Promise((resolve) => (releaseFields = resolve)));
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{");
+    expect(menuOpen()).toBe(false);
+
+    filter!.dispatchEvent(new Event("blur", { bubbles: true }));
+    await flushUi();
+    releaseFields([{ name: "discountCode", type: "string" }]);
+    await flushUi();
+
+    expect(menuOpen()).toBe(false);
+  });
+
+  it("closes rather than splices a stale suggestion when the caret is clicked elsewhere", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{ createdAt: 1, _i");
+    expect(menuOpen()).toBe(true);
+
+    // Into the middle of `createdAt`, where the open suggestions mean nothing.
+    await clickCaretTo(filter!, 3);
+    expect(menuOpen()).toBe(false);
+
+    pressKey(filter!, "Tab");
+    await flushUi();
+    expect(filter!.value).toBe("{ createdAt: 1, _i");
+  });
+
+  it("takes a suggestion clicked with the mouse", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{discountC");
+    const option = document.body.querySelector<HTMLElement>('[role="option"]');
+
+    // The press must not blur the input: blur dismisses, which would unmount
+    // the option before its click could land.
+    const mousedown = new MouseEvent("mousedown", { bubbles: true, cancelable: true });
+    option!.dispatchEvent(mousedown);
+    expect(mousedown.defaultPrevented).toBe(true);
+    option!.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+    await flushUi();
+
+    expect(filter!.value).toBe("{discountCode: ");
+  });
+
+  it("keeps the list usable when its scrollbar is pressed", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{");
+    const mousedown = new MouseEvent("mousedown", { bubbles: true, cancelable: true });
+    menu()!.dispatchEvent(mousedown);
+    await flushUi();
+
+    expect(mousedown.defaultPrevented).toBe(true);
+    expect(menuOpen()).toBe(true);
+  });
+
+  it("closes when an arrow key moves the caret, and lets the key through", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{ createdA");
+    expect(menuOpen()).toBe(true);
+
+    const event = pressKey(filter!, "ArrowLeft");
+    await flushUi();
+
+    expect(menuOpen()).toBe(false);
+    // The caret still has to move — only the menu was consumed.
+    expect(event.defaultPrevented).toBe(false);
+  });
+});
+
+/**
+ * Typing straight into an empty bar, without opening the document first — the
+ * way the issue's reporter did it, and the way anyone who has not noticed the
+ * `{}` placeholder will.
+ */
+describe("DocumentBrowser MongoDB query bars opened by typing (issue #9427)", () => {
+  it("opens the filter document around the first character and suggests from it", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "c");
+
+    expect(filter!.value).toBe("{c}");
+    // Between the braces, in key position — not after the `}` the rewrite added.
+    expect(filter!.selectionStart).toBe(2);
+    expect(menuOpen()).toBe(true);
+    expect(menuOptions()).toEqual(expect.arrayContaining(["createdAt", "customerShippingAddress"]));
+  });
+
+  it("opens the sort document the same way", async () => {
+    await mountBrowser();
+    const [, sort] = queryInputs();
+
+    await typeInto(sort!, "c");
+
+    expect(sort!.value).toBe("{c}");
+    expect(sort!.selectionStart).toBe(2);
+    expect(menuOpen()).toBe(true);
+    // The sort bar is a plain key map, so it offers no query operators.
+    expect(menuOptions()).toEqual(expect.arrayContaining(["createdAt", "customerShippingAddress"]));
+    expect(menuOptions().filter((option) => option.startsWith("$"))).toEqual([]);
+  });
+
+  it("completes a field typed without braces and leaves the caret in value position", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "d");
+    pressKey(filter!, "Tab");
+    await flushUi();
+
+    expect(filter!.value).toBe("{discountCode: }");
+    expect(filter!.selectionStart).toBe(15);
+  });
+
+  it("writes no braces of its own when the user opens the document", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{");
+
+    expect(filter!.value).toBe("{");
+  });
+
+  it("leaves a pasted document alone", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, '{ createdAt: "2026-01-01" }');
+
+    expect(filter!.value).toBe('{ createdAt: "2026-01-01" }');
+  });
+
+  it("leaves a backspace that happens to land on one character alone", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "ab", 2);
+    // Deleting down to `a` leaves the same character and caret as typing it.
+    await typeInto(filter!, "a", 1, "deleteContentBackward");
+
+    expect(filter!.value).toBe("a");
+  });
+
+  it("leaves a character typed mid-text alone", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    // One character long, but the caret is before it: this is an edit, not a start.
+    await typeInto(filter!, "c", 0);
+
+    expect(filter!.value).toBe("c");
+  });
+
+  it("quotes a nested field path so the completed filter still parses", async () => {
+    backend.documentFindDocuments.mockResolvedValue({
+      documents: [{ _id: "1", customer: { name: "Ada", address: { city: "Beijing" } } }],
+      raw_documents: [],
+      total: 1,
+      total_is_exact: true,
+    });
+    backend.listMongoCompletionFields.mockResolvedValue([]);
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "{customer.n}", 11);
+    expect(menuOptions()).toEqual(["customer.name"]);
+
+    pressKey(filter!, "Tab");
+    await flushUi();
+
+    // `{ customer.name: 1 }` is a document in neither the shell nor JSON.
+    expect(filter!.value).toBe('{"customer.name": }');
+    expect(() => JSON.parse(filter!.value.replace(": }", ": 1}"))).not.toThrow();
+  });
+
+  it("still leaves a plain identifier key unquoted", async () => {
+    await mountBrowser();
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "d");
+    pressKey(filter!, "Tab");
+    await flushUi();
+
+    expect(filter!.value).toBe("{discountCode: }");
+  });
+
+  it("does not open documents in the other stores' bars", async () => {
+    await mountBrowser("elasticsearch");
+    const [filter] = queryInputs();
+
+    await typeInto(filter!, "c");
+
+    expect(filter!.value).toBe("c");
+    expect(menuOpen()).toBe(false);
+  });
+});
diff --git a/apps/desktop/src/lib/mongo/__tests__/mongoDocumentQueryCompletion.spec.ts b/apps/desktop/src/lib/mongo/__tests__/mongoDocumentQueryCompletion.spec.ts
new file mode 100644
index 0000000000..270f6c4174
--- /dev/null
+++ b/apps/desktop/src/lib/mongo/__tests__/mongoDocumentQueryCompletion.spec.ts
@@ -0,0 +1,147 @@
+import { describe, expect, it } from "vitest";
+import { buildMongoCompletionItemsFromContext, getMongoDocumentQueryCompletionContext, plainMongoCompletionInsertion, shouldAutoOpenMongoDocumentQueryCompletion, type MongoCompletionField } from "@/lib/mongo/mongoCompletion";
+
+const FIELDS: MongoCompletionField[] = [
+  { name: "_id", type: "objectId" },
+  { name: "customerShippingAddress", type: "string" },
+  { name: "customer.name", type: "string" },
+  { name: "createdAt", type: "date" },
+  { name: "中文字段", type: "string" },
+  { name: "客户 名", type: "string" },
+];
+
+function contextAt(text: string, kind: "filter" | "sortKeys" = "filter", cursor = text.length) {
+  return getMongoDocumentQueryCompletionContext(text, cursor, kind);
+}
+
+function labelsAt(text: string, kind: "filter" | "sortKeys" = "filter", cursor = text.length) {
+  return buildMongoCompletionItemsFromContext(contextAt(text, kind, cursor), { fields: FIELDS }).map((item) => item.label);
+}
+
+describe("getMongoDocumentQueryCompletionContext", () => {
+  it("completes fields at the root of a filter document", () => {
+    expect(contextAt("{ ")).toMatchObject({ mode: "filterField", prefix: "", from: 2 });
+    expect(labelsAt("{ ")).toEqual(expect.arrayContaining(["_id", "customerShippingAddress", "createdAt"]));
+  });
+
+  it("narrows fields by the typed prefix and reports where to splice it", () => {
+    expect(contextAt("{ customerS")).toMatchObject({ mode: "filterField", prefix: "customerS", from: 2 });
+    expect(labelsAt("{ customerS")).toEqual(["customerShippingAddress"]);
+  });
+
+  it("keeps Unicode and quoted spaces in the field prefix and splice range", () => {
+    expect(contextAt("{ 中")).toMatchObject({ mode: "filterField", prefix: "中", from: 2 });
+    expect(labelsAt("{ 中")).toEqual(["中文字段"]);
+    expect(contextAt('{ "客户 名')).toMatchObject({ mode: "filterField", prefix: '"客户 名', from: 2 });
+    expect(labelsAt('{ "客户 名')).toEqual(["客户 名"]);
+  });
+
+  it("matches fields case-insensitively inside a quoted key", () => {
+    expect(contextAt('{ "created')).toMatchObject({ mode: "filterField", prefix: '"created', from: 2 });
+    const items = buildMongoCompletionItemsFromContext(contextAt('{ "created'), { fields: FIELDS });
+    expect(items.map((item) => item.apply)).toContain('"createdAt": ');
+  });
+
+  it("consumes an existing closing quote so a key is not double-quoted", () => {
+    expect(contextAt('{ "created"', "filter", 10)).toMatchObject({ prefix: '"created', replaceClosingQuote: '"' });
+  });
+
+  it("offers whole-filter operators once $ is typed", () => {
+    expect(labelsAt("{ $")).toEqual(expect.arrayContaining(["$and", "$or"]));
+  });
+
+  it("offers query operators inside a field constraint", () => {
+    expect(contextAt("{ createdAt: { $g")).toMatchObject({ mode: "queryOperator", prefix: "$g" });
+    expect(labelsAt("{ createdAt: { $g")).toEqual(expect.arrayContaining(["$gt", "$gte"]));
+  });
+
+  it("offers fields again inside an $and branch and after a comma", () => {
+    expect(contextAt("{ $and: [{ ")).toMatchObject({ mode: "filterField" });
+    expect(contextAt("{ _id: 1, ")).toMatchObject({ mode: "filterField" });
+  });
+
+  it("offers value constructors in value position", () => {
+    expect(contextAt("{ _id: ")).toMatchObject({ mode: "value" });
+    expect(labelsAt("{ _id: ")).toEqual(expect.arrayContaining(["ObjectId"]));
+  });
+
+  it("says nothing inside a string value", () => {
+    expect(contextAt('{ customerShippingAddress: "Beij')).toMatchObject({ mode: "none" });
+  });
+
+  it("says nothing outside the document", () => {
+    expect(contextAt("")).toMatchObject({ mode: "none" });
+    expect(contextAt("{ _id: 1 }")).toMatchObject({ mode: "none" });
+    expect(contextAt("{ _id: 1 } ")).toMatchObject({ mode: "none" });
+    expect(contextAt("}")).toMatchObject({ mode: "none" });
+  });
+
+  it("never offers shell snippets a filter bar cannot hold", () => {
+    // `db.` is a plain token here, not the start of a collection chain.
+    expect(labelsAt("{ db.")).not.toEqual(expect.arrayContaining(["db.getCollection", "find"]));
+  });
+
+  it("completes sort keys without value or operator noise", () => {
+    expect(contextAt("{ created", "sortKeys")).toMatchObject({ mode: "field", prefix: "created" });
+    expect(labelsAt("{ created", "sortKeys")).toEqual(["createdAt"]);
+    expect(contextAt("{ createdAt: ", "sortKeys")).toMatchObject({ mode: "none" });
+    expect(contextAt("{ createdAt: -1, ", "sortKeys")).toMatchObject({ mode: "field" });
+  });
+});
+
+describe("plainMongoCompletionInsertion", () => {
+  it("leaves a plain key completion untouched, caret at the end", () => {
+    expect(plainMongoCompletionInsertion("createdAt: ")).toEqual({ text: "createdAt: ", selectionStart: 11, selectionEnd: 11 });
+  });
+
+  it("drops an empty snippet marker and leaves the caret in its place", () => {
+    expect(plainMongoCompletionInsertion("$gt: ${}")).toEqual({ text: "$gt: ", selectionStart: 5, selectionEnd: 5 });
+    expect(plainMongoCompletionInsertion("$in: [${}]")).toEqual({ text: "$in: []", selectionStart: 6, selectionEnd: 6 });
+  });
+
+  it("selects a named placeholder so its default can be typed over", () => {
+    expect(plainMongoCompletionInsertion('$regex: "${pattern}"')).toEqual({ text: '$regex: "pattern"', selectionStart: 9, selectionEnd: 16 });
+  });
+
+  it("drops the key separator when the text it lands in already has one", () => {
+    expect(plainMongoCompletionInsertion('"createdAt": ', ": 1 }")).toEqual({ text: '"createdAt"', selectionStart: 11, selectionEnd: 11 });
+    expect(plainMongoCompletionInsertion("createdAt: ", "  : 1 }")).toEqual({ text: "createdAt", selectionStart: 9, selectionEnd: 9 });
+    // Nothing to fold into: the separator is still the completion's job.
+    expect(plainMongoCompletionInsertion("createdAt: ", " }").text).toBe("createdAt: ");
+    expect(plainMongoCompletionInsertion("createdAt: ", "").text).toBe("createdAt: ");
+    // An operator snippet ends at its value, so its own colon must survive.
+    expect(plainMongoCompletionInsertion("$gt: ${}", ": 1 }").text).toBe("$gt: ");
+  });
+
+  it("expands every marker but only selects the first", () => {
+    expect(plainMongoCompletionInsertion("$mod: [${divisor}, ${remainder}]")).toEqual({ text: "$mod: [divisor, remainder]", selectionStart: 7, selectionEnd: 14 });
+    expect(plainMongoCompletionInsertion('$split: [${}, "${,}"]')).toEqual({ text: '$split: [, ","]', selectionStart: 9, selectionEnd: 9 });
+  });
+
+  it("renders every operator table entry without leaving a marker behind", () => {
+    const applies = buildMongoCompletionItemsFromContext(contextAt("{ createdAt: { "), { fields: FIELDS })
+      .concat(buildMongoCompletionItemsFromContext(contextAt("{ $"), { fields: FIELDS }))
+      .concat(buildMongoCompletionItemsFromContext(contextAt("{ createdAt: "), { fields: FIELDS }))
+      .map((item) => item.apply ?? item.label);
+    expect(applies.length).toBeGreaterThan(20);
+    for (const apply of applies) {
+      const insertion = plainMongoCompletionInsertion(apply);
+      expect(insertion.text, apply).not.toContain("${");
+      expect(insertion.selectionEnd, apply).toBeLessThanOrEqual(insertion.text.length);
+    }
+  });
+});
+
+describe("shouldAutoOpenMongoDocumentQueryCompletion", () => {
+  it("opens on the characters that start a key, an operator, or a value", () => {
+    for (const text of ["{", "{ ", "{ cre", '{ "cre', "{ 中", '{ "客户 名', "{ $", "{ _id: 1,", "{ createdAt: {", "{ createdAt: "]) {
+      expect(shouldAutoOpenMongoDocumentQueryCompletion(text, text.length, "filter"), text).toBe(true);
+    }
+  });
+
+  it("stays closed where there is nothing to say", () => {
+    for (const text of ["", "{ _id: 1 }", "{ _id: 1 } ", '{ name: "x']) {
+      expect(shouldAutoOpenMongoDocumentQueryCompletion(text, text.length, "filter"), text).toBe(false);
+    }
+  });
+});
diff --git a/apps/desktop/src/lib/mongo/mongoCompletion.ts b/apps/desktop/src/lib/mongo/mongoCompletion.ts
index 1863b21fcb..2b954571e9 100644
--- a/apps/desktop/src/lib/mongo/mongoCompletion.ts
+++ b/apps/desktop/src/lib/mongo/mongoCompletion.ts
@@ -247,7 +247,7 @@ export function getMongoCompletionContext(text: string, cursor: number): MongoCo
   const safeCursor = Math.max(0, Math.min(cursor, text.length));
   const beforeCursor = text.slice(0, safeCursor);
   const collection = extractActiveCollection(text, safeCursor);
-  const { prefix, from } = readPropertyPrefix(text, safeCursor);
+  const { prefix, from } = readMongoPropertyPrefix(text, safeCursor);
   const replaceClosingQuote = closingQuoteAtCursor(prefix, text, safeCursor);
   const at = (mode: MongoCompletionMode, stage?: string): MongoCompletionContext => ({ mode, prefix, from, replaceClosingQuote, collection, stage });
 
@@ -399,6 +399,106 @@ export function shouldAutoOpenMongoCompletion(text: string, cursor: number): boo
   return false;
 }
 
+/* ------------------------------------------------------------------ *
+ * Standalone document inputs
+ * ------------------------------------------------------------------ */
+
+/**
+ * Which bare document an input holds, and therefore how its keys read: the
+ * document browser's filter bar is a query document, its sort bar a key map.
+ */
+export type MongoDocumentQueryKind = "filter" | "sortKeys";
+
+/**
+ * Completion for an input holding one bare document rather than a shell
+ * command — the document browser's filter and sort bars.
+ *
+ * There is no `db.coll.find(…)` here to locate the cursor within, so the text is
+ * scanned as if it *were* that call's argument list: `{ na` lands in the query
+ * document's root object exactly as it would inside `find({ na`. Everything the
+ * shell path reaches by walking the `db.…` chain (collection names, helper
+ * methods, cursor methods) is unreachable by construction, which is what we
+ * want — none of it could be pasted into a filter bar.
+ */
+export function getMongoDocumentQueryCompletionContext(text: string, cursor: number, kind: MongoDocumentQueryKind): MongoCompletionContext {
+  const safeCursor = Math.max(0, Math.min(cursor, text.length));
+  const nothing: MongoCompletionContext = { mode: "none", prefix: "", from: safeCursor };
+  if (isInsideMongoComment(text, safeCursor)) return nothing;
+
+  // Scanning from 0 treats the input as the argument list itself. A `}` that
+  // closes more than the text opened returns null — the cursor has left the
+  // document, e.g. it trails a finished `{ a: 1 }`.
+  const scan = scanMongoCallArguments(text, 0, safeCursor);
+  if (!scan) return nothing;
+
+  const mode = kind === "filter" ? classifyFilter(scan, 0) : classifyKeyMap(scan, 0);
+  if (mode === "none") return nothing;
+
+  const { prefix, from } = readMongoPropertyPrefix(text, safeCursor);
+  return { mode, prefix, from, replaceClosingQuote: closingQuoteAtCursor(prefix, text, safeCursor) };
+}
+
+/** Text to splice into a plain input for a chosen completion, and where to leave the selection. */
+export interface MongoPlainCompletionInsertion {
+  text: string;
+  /** Start of the selection within `text`, relative to its first character. */
+  selectionStart: number;
+  /** End of that selection; equal to the start when the placeholder was empty. */
+  selectionEnd: number;
+}
+
+/**
+ * Renders an item's `apply` string for a plain `<input>`/`<textarea>`.
+ *
+ * Most operator completions are authored as CodeMirror snippets (`$in: [${}]`,
+ * `$regex: "${pattern}"`), and CodeMirror expands the `${…}` markers itself.
+ * Nothing does that outside the editor, so strip the markers and hand back the
+ * span of the first placeholder: an empty one becomes the caret position, a
+ * named one is selected so its default can be typed straight over.
+ *
+ * Key completions carry their own `: ` because they are only offered in key
+ * position. Pass `followingText` — whatever the input holds after the replaced
+ * range — so re-picking the key of an existing `{ "name": 1 }` entry replaces
+ * the key instead of leaving `{ "other": : 1 }` behind.
+ */
+export function plainMongoCompletionInsertion(apply: string, followingText = ""): MongoPlainCompletionInsertion {
+  let text = "";
+  let selection: { start: number; end: number } | null = null;
+  let rest = apply;
+
+  for (;;) {
+    const match = /\$\{([^{}]*)\}/.exec(rest);
+    if (!match) break;
+    const placeholder = match[1] ?? "";
+    text += rest.slice(0, match.index);
+    if (!selection) selection = { start: text.length, end: text.length + placeholder.length };
+    text += placeholder;
+    rest = rest.slice(match.index + match[0].length);
+  }
+  text += rest;
+
+  // Only a plain key completion may fold its separator away. A snippet's colon
+  // introduces the placeholder that follows it (`$gt: ${}`), so it is never the
+  // same colon as one already in the text.
+  if (!selection && text.endsWith(": ") && /^\s*:/.test(followingText)) text = text.slice(0, -2);
+
+  return { text, selectionStart: Math.min(selection?.start ?? text.length, text.length), selectionEnd: Math.min(selection?.end ?? text.length, text.length) };
+}
+
+/**
+ * Whether typing the character before the cursor should pop the menu open on its
+ * own. Mirrors `shouldAutoOpenMongoCompletion` minus the `db.` chain, and
+ * confirms the position has something to say so a space or a closing brace does
+ * not reopen an empty menu.
+ */
+export function shouldAutoOpenMongoDocumentQueryCompletion(text: string, cursor: number, kind: MongoDocumentQueryKind): boolean {
+  const previousChar = text[cursor - 1];
+  if (!previousChar) return false;
+  const context = getMongoDocumentQueryCompletionContext(text, cursor, kind);
+  if (context.mode === "none") return false;
+  return context.prefix.length > 0 || /[{[,:]\s*$/.test(text.slice(0, cursor));
+}
+
 /**
  * How far the editor may keep re-filtering a result before it has to ask us
  * again. In the `db.…` chain every `.` moves the cursor to a different item
@@ -910,11 +1010,47 @@ function finalizeQuotedMongoCompletionItems(context: MongoCompletionContext, ite
  * Text helpers
  * ------------------------------------------------------------------ */
 
-function readPropertyPrefix(text: string, cursor: number): { prefix: string; from: number } {
-  let from = cursor;
-  while (from > 0 && /[\w_$.-]/.test(text[from - 1] ?? "")) from--;
-  if (text[from - 1] === '"' || text[from - 1] === "'") from--;
-  return { prefix: text.slice(from, cursor), from };
+const MONGO_PROPERTY_PREFIX_CHARACTER = /[$.\p{ID_Continue}-]/u;
+
+export function readMongoPropertyPrefix(text: string, cursor: number): { prefix: string; from: number } {
+  const safeCursor = Math.max(0, Math.min(cursor, text.length));
+  const quoteStart = findOpenMongoQuoteStart(text, safeCursor);
+  if (quoteStart !== null) return { prefix: text.slice(quoteStart, safeCursor), from: quoteStart };
+
+  let from = safeCursor;
+  while (from > 0) {
+    let candidateFrom = from - 1;
+    const trailingUnit = text.charCodeAt(candidateFrom);
+    if (trailingUnit >= 0xdc00 && trailingUnit <= 0xdfff && candidateFrom > 0) {
+      const leadingUnit = text.charCodeAt(candidateFrom - 1);
+      if (leadingUnit >= 0xd800 && leadingUnit <= 0xdbff) candidateFrom--;
+    }
+    const candidate = text.slice(candidateFrom, from);
+    if (!MONGO_PROPERTY_PREFIX_CHARACTER.test(candidate)) break;
+    from = candidateFrom;
+  }
+  return { prefix: text.slice(from, safeCursor), from };
+}
+
+function findOpenMongoQuoteStart(text: string, cursor: number): number | null {
+  for (let index = 0; index < cursor; index++) {
+    const char = text[index];
+    if ((char === "/" && (text[index + 1] === "/" || text[index + 1] === "*")) || (char === "-" && text[index + 1] === "-")) {
+      const skipped = skipMongoStringOrComment(text, index, cursor);
+      if (skipped >= cursor) return null;
+      index = skipped - 1;
+      continue;
+    }
+    if (char !== '"' && char !== "'") continue;
+
+    const quoteStart = index;
+    for (index++; index < cursor; index++) {
+      if (text[index] === "\\") index++;
+      else if (text[index] === char) break;
+    }
+    if (index >= cursor) return quoteStart;
+  }
+  return null;
 }
 
 function closingQuoteAtCursor(prefix: string, text: string, cursor: number): '"' | "'" | undefined {
@@ -1116,9 +1252,23 @@ function describeMongoValueType(value: unknown): string {
   return mongoExtendedJsonValueType(value) ?? (typeof value === "object" ? "object" : typeof value);
 }
 
+/**
+ * Keys that may be written bare. Anything else has to carry quotes: a nested
+ * path (`customer.name`) is the common case, but a hyphen or a leading digit
+ * does it too. `inferMongoCompletionFields` emits a path per nesting level, so
+ * a collection of nested documents offers mostly non-bare keys.
+ */
+const BARE_MONGO_KEY = /^[A-Za-z_$][A-Za-z0-9_$]*$/;
+
+/**
+ * Renders a field name in key position. An unquoted prefix keeps the key bare
+ * only while the name allows it — `{ customer.name: 1 }` parses neither as a
+ * shell document nor as the JSON the document browser's query bars are read
+ * as, so a path is quoted even though the user typed no quote.
+ */
 function quoteMongoFieldName(field: string, prefix: string): string {
-  if (prefix.startsWith('"')) return `"${escapeDoubleQuoted(field)}"`;
   if (prefix.startsWith("'")) return `'${escapeSingleQuoted(field)}'`;
+  if (prefix.startsWith('"') || !BARE_MONGO_KEY.test(field)) return `"${escapeDoubleQuoted(field)}"`;
   return field;
 }
 
diff --git a/packages/app-tests/documentBrowser.test.ts b/packages/app-tests/documentBrowser.test.ts
index 3813bea6ae..502599f75f 100644
--- a/packages/app-tests/documentBrowser.test.ts
+++ b/packages/app-tests/documentBrowser.test.ts
@@ -95,6 +95,12 @@ test("document pagination commits page index with fetched rows", () => {
 
 test("document query inputs apply on Enter and reserve Shift+Enter for newlines", () => {
   const source = documentBrowserSource();
-  assert.equal(source.match(/@keydown\.enter\.exact\.prevent="applyFilter"/g)?.length, 2);
+  // Both bars route every key through one handler, because Enter has to pick a
+  // pending completion before it may run the query.
+  assert.equal(source.match(/@keydown="onDocumentQueryKeydown\(\$event, '(?:filter|sort)'\)"/g)?.length, 2);
+  assert.match(source, /const plainEnter = !event\.ctrlKey && !event\.metaKey && !event\.altKey && !event\.shiftKey;/);
+  // Plain Enter and Ctrl/Cmd+Enter apply; Shift+Enter and Alt+Enter fall
+  // through to the textarea so they still insert a newline.
+  assert.match(source, /if \(!plainEnter && !\(\(event\.ctrlKey \|\| event\.metaKey\) && !event\.altKey && !event\.shiftKey\)\) return;/);
   assert.doesNotMatch(source, /@keydown\.shift\.enter\.prevent="applyFilter"/);
 });