diff --git a/apps/desktop/src/components/editor/QueryEditor.vue b/apps/desktop/src/components/editor/QueryEditor.vue
index 7e447c045f..d05d1a2655 100644
--- a/apps/desktop/src/components/editor/QueryEditor.vue
+++ b/apps/desktop/src/components/editor/QueryEditor.vue
@@ -772,6 +772,7 @@ function editorIndentUnit(): string {
 }
 
 function handleTab(view: EditorViewType): boolean {
+  if (view.state.selection.ranges.some((range) => !range.empty)) return codeMirrorIndentMore?.(view) ?? false;
   if (tabKeyAcceptsCompletion()) {
     return acceptCompletionOrNextSnippetField(view) || performNormalTab(view);
   }
@@ -795,8 +796,8 @@ function handleTabWithoutAcceptingCompletion(view: EditorViewType): boolean {
 
 function performNormalTab(view: EditorViewType): boolean {
   const { state, dispatch } = view;
+  if (state.selection.ranges.some((range) => !range.empty)) return codeMirrorIndentMore?.(view) ?? false;
   const sel = state.selection.main;
-  if (!sel.empty) return codeMirrorIndentMore?.(view) ?? false;
   const line = state.doc.lineAt(sel.from);
   const before = line.text.slice(0, sel.from - line.from);
   if (/^\s*$/.test(before)) return codeMirrorIndentMore?.(view) ?? false;
@@ -1974,9 +1975,14 @@ function extendQueryEditorSelectionForView(currentView: EditorViewType): boolean
 }
 
 function acceptCompletionOrNextSnippetField(view: EditorViewType): boolean {
-  const completionStatus = codeMirrorCompletionStatus?.(view.state) ?? null;
-  if (completionStatus === "active" && (codeMirrorAcceptCompletion?.(view) ?? false)) return true;
-  if (completionStatus) return waitForCompletionTab(view);
+  // Any non-empty selection range means Tab is being used for block indent,
+  // not word completion. A completion popup can still appear as a side effect
+  // of the indent edit itself, so it must never hijack this or a following Tab.
+  if (view.state.selection.ranges.every((range) => range.empty)) {
+    const completionStatus = codeMirrorCompletionStatus?.(view.state) ?? null;
+    if (completionStatus === "active" && (codeMirrorAcceptCompletion?.(view) ?? false)) return true;
+    if (completionStatus) return waitForCompletionTab(view);
+  }
   return codeMirrorNextSnippetField?.(view) ?? false;
 }
 
@@ -1989,13 +1995,13 @@ function clearPendingCompletionTab() {
 function waitForCompletionTab(view: EditorViewType): boolean {
   clearPendingCompletionTab();
   const initialDoc = view.state.doc;
-  const initialSelection = view.state.selection.main;
+  const initialSelectionRanges = view.state.selection.ranges.map((range) => ({ anchor: range.anchor, head: range.head }));
   const startedAt = Date.now();
 
   const retry = () => {
     pendingCompletionTabTimer = null;
-    const selection = view.state.selection.main;
-    if (view.state.doc !== initialDoc || selection.anchor !== initialSelection.anchor || selection.head !== initialSelection.head) return;
+    const selectionRanges = view.state.selection.ranges;
+    if (view.state.doc !== initialDoc || selectionRanges.length !== initialSelectionRanges.length || selectionRanges.some((range, index) => !range.empty || range.anchor !== initialSelectionRanges[index]?.anchor || range.head !== initialSelectionRanges[index]?.head)) return;
 
     const completionStatus = codeMirrorCompletionStatus?.(view.state) ?? null;
     if (completionStatus === "active" && (codeMirrorAcceptCompletion?.(view) ?? false)) return;
diff --git a/apps/desktop/src/lib/__tests__/editor/queryEditorCompletionKeymap.spec.ts b/apps/desktop/src/lib/__tests__/editor/queryEditorCompletionKeymap.spec.ts
index bc99cd5b90..54f49f8ee4 100644
--- a/apps/desktop/src/lib/__tests__/editor/queryEditorCompletionKeymap.spec.ts
+++ b/apps/desktop/src/lib/__tests__/editor/queryEditorCompletionKeymap.spec.ts
@@ -35,7 +35,7 @@ interface MockState {
   doc: {
     lineAt: (position: number) => { from: number; text: string };
   };
-  selection: { main: MockSelection };
+  selection: { main: MockSelection; ranges: MockSelection[] };
   replaceSelection: ReturnType<typeof vi.fn>;
   update: ReturnType<typeof vi.fn>;
 }
@@ -117,19 +117,27 @@ function createHarness(options: {
   ) as TabHarness;
 }
 
-function createView(text = "SELECT", position = text.length): MockView {
-  const selection: MockSelection = { anchor: position, head: position, from: position, empty: true };
+function createView(text = "SELECT", position = text.length, selectionOverrides: Partial<MockSelection> = {}, additionalRanges: MockSelection[] = []): MockView {
+  const selection: MockSelection = { anchor: position, head: position, from: position, empty: true, ...selectionOverrides };
   const state: MockState = {
     doc: {
       lineAt: () => ({ from: 0, text }),
     },
-    selection: { main: selection },
+    selection: { main: selection, ranges: [selection, ...additionalRanges] },
     replaceSelection: vi.fn((insert: string) => ({ insert })),
     update: vi.fn((change: unknown, options: unknown) => ({ change, options })),
   };
   return { state, dispatch: vi.fn() };
 }
 
+function createMultiLineSelectionView(text = "SELECT 1\nSELECT 2"): MockView {
+  return createView(text, 0, { anchor: 0, head: text.length, from: 0, empty: false });
+}
+
+function createMixedMultiRangeView(text = "SELECT 1\nSELECT 2"): MockView {
+  return createView(text, text.length, {}, [{ anchor: 0, head: 6, from: 0, empty: false }]);
+}
+
 afterEach(() => {
   vi.useRealTimers();
 });
@@ -281,6 +289,67 @@ describe("QueryEditor completion Tab keymap", () => {
     expect(acceptCompletion).toHaveBeenCalledWith(view);
   });
 
+  it("keeps indenting a multi-line selection instead of letting a completion popup hijack Tab (#5419)", () => {
+    const acceptCompletion = vi.fn(() => true);
+    const indentMore = vi.fn(() => true);
+    const harness = createHarness({ completionStatus: () => "active", acceptCompletion, indentMore });
+    const view = createMultiLineSelectionView();
+
+    expect(harness.handleTab(view)).toBe(true);
+    expect(indentMore).toHaveBeenCalledWith(view);
+    expect(acceptCompletion).not.toHaveBeenCalled();
+  });
+
+  it("does not let a pending completion hijack a second Tab press while indenting a selection (#5419)", async () => {
+    vi.useFakeTimers();
+    let status: "active" | "pending" | null = "pending";
+    const acceptCompletion = vi.fn(() => true);
+    const indentMore = vi.fn(() => true);
+    const harness = createHarness({ completionStatus: () => status, acceptCompletion, indentMore });
+    const view = createMultiLineSelectionView();
+
+    expect(harness.handleTab(view)).toBe(true);
+    status = "active";
+    await vi.advanceTimersByTimeAsync(32);
+
+    expect(indentMore).toHaveBeenCalledWith(view);
+    expect(acceptCompletion).not.toHaveBeenCalled();
+  });
+
+  it("indents mixed multi-range selections instead of accepting an active completion", () => {
+    const completionStatus = vi.fn(() => "active" as const);
+    const acceptCompletion = vi.fn(() => true);
+    const nextSnippetField = vi.fn(() => true);
+    const indentMore = vi.fn(() => true);
+    const harness = createHarness({ completionStatus, acceptCompletion, nextSnippetField, indentMore });
+    const view = createMixedMultiRangeView();
+
+    expect(harness.handleTab(view)).toBe(true);
+    expect(indentMore).toHaveBeenCalledWith(view);
+    expect(completionStatus).not.toHaveBeenCalled();
+    expect(acceptCompletion).not.toHaveBeenCalled();
+    expect(nextSnippetField).not.toHaveBeenCalled();
+    expect(view.state.replaceSelection).not.toHaveBeenCalled();
+  });
+
+  it("does not accept or wait for completion when a mixed multi-range selection is active", async () => {
+    vi.useFakeTimers();
+    let status: "active" | "pending" | null = "pending";
+    const completionStatus = vi.fn(() => status);
+    const acceptCompletion = vi.fn(() => true);
+    const harness = createHarness({ completionStatus, acceptCompletion });
+    const view = createMixedMultiRangeView();
+
+    expect(harness.acceptCompletionOrNextSnippetField(view)).toBe(false);
+    status = "active";
+    await vi.advanceTimersByTimeAsync(32);
+
+    expect(completionStatus).not.toHaveBeenCalled();
+    expect(acceptCompletion).not.toHaveBeenCalled();
+    expect(view.dispatch).not.toHaveBeenCalled();
+    expect(view.state.replaceSelection).not.toHaveBeenCalled();
+  });
+
   it("falls back to normal Tab when pending completion has no candidate", async () => {
     vi.useFakeTimers();
     let status: "active" | "pending" | null = "pending";