fix(editor): isolate per-tab undo history on tab switches

apps/desktop/src/components/editor/QueryEditor.vue

@@ -178,6 +178,8 @@ import type { CompletionAssistantObjectKind, ColumnInfo, DatabaseType, IndexInfo
 
 const props = defineProps<{
   modelValue: string;
+  /** Identity of the tab owning the document. Changing it swaps in that tab's cached editor state (fresh undo history on first visit). */
+  tabId?: string;
   connectionId?: string;
   catalog?: string;
   database?: string;
@@ -557,6 +559,8 @@ let codeMirrorCloseBracketsKeymap: readonly import("@codemirror/view").KeyBindin
 let readOnlyComp: import("@codemirror/state").Compartment | null = null;
 let runGutterComp: import("@codemirror/state").Compartment | null = null;
 let runKeymapComp: import("@codemirror/state").Compartment | null = null;
+let historyResetComp: import("@codemirror/state").Compartment | null = null;
+let codeMirrorHistory: typeof import("@codemirror/commands").history | null = null;
 let defaultKeymapComp: import("@codemirror/state").Compartment | null = null;
 let completionComp: import("@codemirror/state").Compartment | null = null;
 let diagnosticComp: import("@codemirror/state").Compartment | null = null;
@@ -5632,6 +5636,7 @@ onMounted(async () => {
   readOnlyComp = new Compartment();
   runGutterComp = new Compartment();
   runKeymapComp = new Compartment();
+  historyResetComp = new Compartment();
   defaultKeymapComp = new Compartment();
   completionComp = new Compartment();
   diagnosticComp = new Compartment();
@@ -5659,6 +5664,7 @@ onMounted(async () => {
   codeMirrorMoveLineDown = moveLineDown;
   codeMirrorUndo = undo;
   codeMirrorRedo = redo;
+  codeMirrorHistory = history;
   codeMirrorSelectAll = selectAll;
   codeMirrorInsertNewlineKeepIndent = insertNewlineKeepIndent;
   codeMirrorToggleLineComment = toggleLineComment;
@@ -6122,7 +6128,7 @@ onMounted(async () => {
       currentStatementFrameExtension,
       highlightActiveLineGutter(),
       highlightSpecialChars(),
-      history(),
+      historyResetComp.of(history()),
       foldGutter({
         markerDOM(open: boolean) {
           const span = document.createElement("span");
@@ -6657,18 +6663,83 @@ watch(
   },
 );
 
-watch(
-  () => props.modelValue,
-  (val) => {
-    if (view.value && val !== view.value.state.doc.toString()) {
-      if (isEditorComposing(view.value)) return;
-      view.value.dispatch({
-        changes: { from: 0, to: view.value.state.doc.length, insert: val },
-      });
-      scheduleSemanticDiagnostics();
+// A single editor instance serves every tab, so the document swap on tab
+// switches must not push "previous tab's content → new content" onto a shared
+// undo history (one undo in the new tab restored the old tab's text). Each
+// tab's editor state — including its undo history — is cached per tabId and
+// reinstalled with setState; first-seen tabs get the document swapped in with a
+// transaction excluded from history, and the history extension is dropped and
+// re-added in two separate transactions (a compartment reconfigure alone keeps
+// the old field value) so the previous tab's edits cannot leak in.
+const tabStateCache = new Map<string, import("@codemirror/state").EditorState>();
+const MAX_CACHED_TAB_STATES = 16;
+
+function swapEditorDocument(doc: string) {
+  const currentView = view.value;
+  if (!currentView || !historyResetComp || !codeMirrorHistory) return;
+  if (doc !== currentView.state.doc.toString()) {
+    currentView.dispatch({
+      changes: { from: 0, to: currentView.state.doc.length, insert: doc },
+      annotations: Transaction.addToHistory.of(false),
+    });
+  }
+  currentView.dispatch({ effects: historyResetComp.reconfigure([]) });
+  currentView.dispatch({ effects: historyResetComp.reconfigure(codeMirrorHistory()) });
+  scheduleSemanticDiagnostics();
+}
+
+function activateTabDocument(prevTabId: string | undefined, tabId: string | undefined, doc: string) {
+  const currentView = view.value;
+  if (!currentView) return;
+  if (prevTabId !== undefined) {
+    tabStateCache.set(prevTabId, currentView.state);
+    if (tabStateCache.size > MAX_CACHED_TAB_STATES) {
+      const oldest = tabStateCache.keys().next();
+      if (!oldest.done) tabStateCache.delete(oldest.value);
     }
-  },
-);
+  }
+  const cached = tabId === undefined ? undefined : tabStateCache.get(tabId);
+  if (!cached) {
+    swapEditorDocument(doc);
+    return;
+  }
+  // setState swaps doc, selection, undo history and all fields at once, but it
+  // is not a transaction, so update-listener side effects are re-run manually.
+  currentView.setState(cached);
+  // Compartments in the restored state may lag behind settings that changed
+  // while another tab was active; re-sync them from current values.
+  void applyEditorAppearance();
+  applyEditorShortcutKeymaps();
+  applyEditorIndentExtension();
+  applyEditorCompletionExtension();
+  if (doc !== currentView.state.doc.toString()) {
+    // Content changed while the tab was inactive (external file change, AI
+    // edit, another split group): apply it as a regular undoable edit.
+    currentView.dispatch({
+      changes: { from: 0, to: currentView.state.doc.length, insert: doc },
+    });
+  }
+  searchPanelRef.value?.scheduleDocumentSearchUpdate();
+  invalidateSemanticDiagnosticsForDocumentChange();
+  restoreEditorSelection();
+  restoreEditorViewport();
+  scheduleSemanticDiagnostics();
+}
+
+watch([() => props.tabId, () => props.modelValue], ([tabId, val], [prevTabId]) => {
+  if (!view.value) return;
+  if (tabId !== prevTabId) {
+    activateTabDocument(prevTabId, tabId, val);
+    return;
+  }
+  if (val !== view.value.state.doc.toString()) {
+    if (isEditorComposing(view.value)) return;
+    view.value.dispatch({
+      changes: { from: 0, to: view.value.state.doc.length, insert: val },
+    });
+    scheduleSemanticDiagnostics();
+  }
+});
 
 watch(
   () => props.formatRequestId,
@@ -6782,75 +6853,97 @@ function getCurrentCustomThemeColors() {
   return activeTheme?.colors ?? settings.customThemeColors;
 }
 
-// Reactively apply editor settings changes
+// Reactively apply editor settings changes. Also called after restoring a
+// cached per-tab state, whose compartments predate any settings changed while
+// another tab was active.
+async function applyEditorAppearance() {
+  const ss = queryEditorAppearanceSettings.value;
+  if (!view.value || !codeMirrorTheme || !fontThemeComp || !wordWrapComp || !lineNumbersComp || !vimModeComp || !closeBracketsComp || !runGutterComp || !runKeymapComp || !editorViewModule) {
+    return;
+  }
+  if (!isGestureZooming.value && !zoomCommitScheduler.hasPendingCommit() && liveFontSize.value !== ss.fontSize) {
+    liveFontSize.value = ss.fontSize;
+  }
+  syncEditorFontCssVars(liveFontSize.value, ss.fontFamily);
+  syncEditorDiagnosticCssVars();
+  const themeColors = getCurrentCustomThemeColors();
+  const [themeExt] = await Promise.all([loadEditorTheme(ss.theme, editorThemeAppearance(), themeColors, themePalette.value), ss.vimModeEnabled ? ensureCodeMirrorVim() : Promise.resolve(false)]);
+  if (!view.value || !codeMirrorTheme || !wordWrapComp || !lineNumbersComp || !vimModeComp || !closeBracketsComp || !runGutterComp || !runKeymapComp || !editorViewModule) {
+    return;
+  }
+  view.value.dispatch({
+    effects: [
+      codeMirrorTheme.reconfigure(themeExt),
+      wordWrapComp.reconfigure(props.forceWordWrap || ss.wordWrap ? editorViewModule.EditorView.lineWrapping : []),
+      lineNumbersComp.reconfigure(lineNumbersExtension(ss.showLineNumbers)),
+      vimModeComp.reconfigure(vimModeExtension(settingsStore.editorSettings.vimModeEnabled)),
+      closeBracketsComp.reconfigure(closeBracketsExtension(settingsStore.editorSettings.autoCloseBrackets)),
+      runGutterComp.reconfigure(runStatementGutterExtension()),
+      runKeymapComp.reconfigure(runKeymapExtension(editorViewModule.keymap)),
+    ],
+  });
+}
+
 watch(
   [queryEditorAppearanceSettings, () => isDark.value, () => themePalette.value, editorThemeAppearance],
-  async ([ss]) => {
-    if (!view.value || !codeMirrorTheme || !fontThemeComp || !wordWrapComp || !lineNumbersComp || !vimModeComp || !closeBracketsComp || !runGutterComp || !runKeymapComp || !editorViewModule) {
-      return;
-    }
-    if (!isGestureZooming.value && !zoomCommitScheduler.hasPendingCommit() && liveFontSize.value !== ss.fontSize) {
-      liveFontSize.value = ss.fontSize;
-    }
-    syncEditorFontCssVars(liveFontSize.value, ss.fontFamily);
-    syncEditorDiagnosticCssVars();
-    const themeColors = getCurrentCustomThemeColors();
-    const [themeExt] = await Promise.all([loadEditorTheme(ss.theme, editorThemeAppearance(), themeColors, themePalette.value), ss.vimModeEnabled ? ensureCodeMirrorVim() : Promise.resolve(false)]);
-    if (!view.value || !codeMirrorTheme || !wordWrapComp || !lineNumbersComp || !vimModeComp || !closeBracketsComp || !runGutterComp || !runKeymapComp || !editorViewModule) {
-      return;
-    }
-    view.value.dispatch({
-      effects: [
-        codeMirrorTheme.reconfigure(themeExt),
-        wordWrapComp.reconfigure(props.forceWordWrap || ss.wordWrap ? editorViewModule.EditorView.lineWrapping : []),
-        lineNumbersComp.reconfigure(lineNumbersExtension(ss.showLineNumbers)),
-        vimModeComp.reconfigure(vimModeExtension(settingsStore.editorSettings.vimModeEnabled)),
-        closeBracketsComp.reconfigure(closeBracketsExtension(settingsStore.editorSettings.autoCloseBrackets)),
-        runGutterComp.reconfigure(runStatementGutterExtension()),
-        runKeymapComp.reconfigure(runKeymapExtension(editorViewModule.keymap)),
-      ],
-    });
+  () => {
+    void applyEditorAppearance();
   },
   { deep: true },
 );
 
+// Re-sync shortcut-driven keymap compartments; shared with per-tab state restore.
+function applyEditorShortcutKeymaps() {
+  if (!view.value || !editorViewModule) return;
+  const effects = [];
+  if (defaultKeymapComp) {
+    effects.push(defaultKeymapComp.reconfigure(defaultKeymapExtension()));
+  }
+  if (runKeymapComp) {
+    effects.push(runKeymapComp.reconfigure(runKeymapExtension(editorViewModule.keymap)));
+  }
+  if (effects.length > 0) {
+    view.value.dispatch({ effects });
+  }
+}
+
 watch(
   () => [settingsStore.editorSettings.shortcuts, settingsStore.editorSettings.sqlShortcuts],
   () => {
-    if (!view.value || !editorViewModule) return;
-    const effects = [];
-    if (defaultKeymapComp) {
-      effects.push(defaultKeymapComp.reconfigure(defaultKeymapExtension()));
-    }
-    if (runKeymapComp) {
-      effects.push(runKeymapComp.reconfigure(runKeymapExtension(editorViewModule.keymap)));
-    }
-    if (effects.length > 0) {
-      view.value.dispatch({ effects });
-    }
+    applyEditorShortcutKeymaps();
   },
   { deep: true },
 );
 
+// Re-sync the indent compartment; shared with per-tab state restore.
+function applyEditorIndentExtension() {
+  if (!view.value || !indentComp) return;
+  view.value.dispatch({ effects: indentComp.reconfigure(indentExtension()) });
+}
+
 watch(
   () => [settingsStore.editorSettings.sqlFormatter.tabWidth, settingsStore.editorSettings.sqlFormatter.useTabs],
   () => {
-    if (!view.value || !indentComp) return;
-    view.value.dispatch({ effects: indentComp.reconfigure(indentExtension()) });
+    applyEditorIndentExtension();
   },
 );
 
+// Re-sync the completion compartment; shared with per-tab state restore.
+function applyEditorCompletionExtension() {
+  completionEpoch++;
+  if (!view.value || !completionComp || !buildSqlCompletionExtension) return;
+  view.value.dispatch({
+    effects: completionComp.reconfigure(buildSqlCompletionExtension()),
+  });
+  if (codeMirrorCompletionStatus?.(view.value.state) === "active") {
+    codeMirrorStartCompletion?.(view.value);
+  }
+}
+
 watch(
   () => [settingsStore.editorSettings.snippets, settingsStore.editorSettings.sortCompletionColumnsAlphabetically, settingsStore.editorSettings.selectFirstCompletionOnOpen],
   () => {
-    completionEpoch++;
-    if (!view.value || !completionComp || !buildSqlCompletionExtension) return;
-    view.value.dispatch({
-      effects: completionComp.reconfigure(buildSqlCompletionExtension()),
-    });
-    if (codeMirrorCompletionStatus?.(view.value.state) === "active") {
-      codeMirrorStartCompletion?.(view.value);
-    }
+    applyEditorCompletionExtension();
   },
   { deep: true },
 );

apps/desktop/src/components/layout/ContentArea.vue

@@ -1275,6 +1275,7 @@ defineExpose({
               class="relative z-0 flex-1"
               :auto-focus="autoFocus !== false"
               :model-value="activeTab.sql"
+              :tab-id="activeTab.id"
               :connection-id="activeTab.connectionId"
               :catalog="activeTab.catalog"
               :database="activeTab.database"