diff --git a/apps/desktop/src/components/editor/SqlPreviewPanel.vue b/apps/desktop/src/components/editor/SqlPreviewPanel.vue
index 6aff7d003d..6c06aa299c 100644
--- a/apps/desktop/src/components/editor/SqlPreviewPanel.vue
+++ b/apps/desktop/src/components/editor/SqlPreviewPanel.vue
@@ -60,11 +60,41 @@ function selectPreviewContent() {
   return true;
 }
 
+/** Text the user actually highlighted inside the preview, if any. */
+function selectedPreviewText(): string {
+  const selection = window.getSelection();
+  if (!selection || selection.isCollapsed || selection.rangeCount === 0) return "";
+  const el = contentRef.value;
+  if (!el) return "";
+  // Only a selection that lives inside this preview counts; one leaked from the
+  // surrounding grid must not be copied as if it were the preview text.
+  for (let index = 0; index < selection.rangeCount; index += 1) {
+    const range = selection.getRangeAt(index);
+    if (!el.contains(range.commonAncestorContainer)) return "";
+  }
+  return selection.toString();
+}
+
+async function copySelectionOrAll(event: KeyboardEvent) {
+  const text = selectedPreviewText() || displaySql.value;
+  if (!text.trim()) return;
+  event.preventDefault();
+  event.stopPropagation();
+  await copyPreviewText(text);
+}
+
 function onContentKeydown(event: KeyboardEvent) {
-  if (!isPlainClipboardShortcut(event, "a")) return;
-  // Claim the shortcut before it reaches the surrounding data grid, then select
-  // the preview text instead of the grid cells.
-  if (selectPreviewContent()) event.preventDefault();
+  if (isPlainClipboardShortcut(event, "a")) {
+    // Claim the shortcut before it reaches the surrounding data grid, then select
+    // the preview text instead of the grid cells.
+    if (selectPreviewContent()) event.preventDefault();
+    return;
+  }
+  // A programmatically built selection (Ctrl+A above) is not guaranteed to reach
+  // the system clipboard through the webview's native copy, so copy it through the
+  // app clipboard instead: the toast already claimed success that never happened
+  // (#12167).
+  if (isPlainClipboardShortcut(event, "c")) void copySelectionOrAll(event);
 }
 
 async function initHighlighter() {
@@ -114,6 +144,10 @@ async function toggleFormat() {
 async function handleCopy() {
   const text = displaySql.value;
   if (!text.trim()) return;
+  await copyPreviewText(text);
+}
+
+async function copyPreviewText(text: string) {
   try {
     await copyToClipboard(text);
     toast(t("grid.copied"));
diff --git a/apps/desktop/src/components/editor/__tests__/SqlPreviewPanel.spec.ts b/apps/desktop/src/components/editor/__tests__/SqlPreviewPanel.spec.ts
index 14921a5de1..840d89f35f 100644
--- a/apps/desktop/src/components/editor/__tests__/SqlPreviewPanel.spec.ts
+++ b/apps/desktop/src/components/editor/__tests__/SqlPreviewPanel.spec.ts
@@ -5,16 +5,23 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
 const mocks = vi.hoisted(() => ({
   highlight: vi.fn<(content: string) => string>(() => ""),
+  copyToClipboard: vi.fn<(_text: string) => Promise<void>>(async () => {}),
+  toast: vi.fn(),
 }));
 
 vi.mock("vue-i18n", () => ({ useI18n: () => ({ t: (key: string) => key }) }));
 vi.mock("@/composables/useTheme", () => ({ useTheme: () => ({ isDark: { value: false } }) }));
-vi.mock("@/composables/useToast", () => ({ useToast: () => ({ toast: vi.fn() }) }));
+vi.mock("@/composables/useToast", () => ({ useToast: () => ({ toast: mocks.toast }) }));
 vi.mock("@/stores/settingsStore", () => ({ useSettingsStore: () => ({ editorSettings: { sqlFormatter: {} } }) }));
 vi.mock("@/lib/sql/sqlHighlighter", () => ({
   createShikiSqlHighlighter: async () => (content: string) => mocks.highlight(content),
 }));
 
+vi.mock("@/lib/common/clipboard", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("@/lib/common/clipboard")>();
+  return { ...actual, copyToClipboard: mocks.copyToClipboard };
+});
+
 vi.mock("@/components/ui/button", async () => {
   const { defineComponent, h } = await import("vue");
   return {
@@ -74,8 +81,30 @@ function dispatchSelectAll(target: HTMLElement, modifiers: KeyboardEventInit = {
   return event;
 }
 
+function dispatchCopy(target: HTMLElement, modifiers: KeyboardEventInit = { ctrlKey: true }) {
+  const event = new KeyboardEvent("keydown", { key: "c", bubbles: true, cancelable: true, ...modifiers });
+  target.dispatchEvent(event);
+  return event;
+}
+
+/** Builds a selection the way a mouse drag would: a sub-range of the preview text. */
+function dragSelect(pre: HTMLElement, start: number, end: number) {
+  const textNode = pre.firstChild;
+  if (!textNode) throw new Error("preview text node not found");
+  const range = document.createRange();
+  range.setStart(textNode, start);
+  range.setEnd(textNode, end);
+  const selection = window.getSelection();
+  selection?.removeAllRanges();
+  selection?.addRange(range);
+  return selection;
+}
+
 beforeEach(() => {
   mocks.highlight.mockImplementation(() => "");
+  mocks.copyToClipboard.mockClear();
+  mocks.copyToClipboard.mockImplementation(async () => {});
+  mocks.toast.mockClear();
 });
 
 afterEach(() => {
@@ -85,6 +114,8 @@ afterEach(() => {
   host?.remove();
   host = null;
   mocks.highlight.mockClear();
+  mocks.copyToClipboard.mockClear();
+  mocks.toast.mockClear();
 });
 
 describe("SqlPreviewPanel select all", () => {
@@ -127,9 +158,6 @@ describe("SqlPreviewPanel select all", () => {
     expect(dispatchSelectAll(pre, { ctrlKey: true, shiftKey: true }).defaultPrevented).toBe(false);
     expect(dispatchSelectAll(pre, { ctrlKey: true, altKey: true }).defaultPrevented).toBe(false);
     expect(dispatchSelectAll(pre, { ctrlKey: false }).defaultPrevented).toBe(false);
-    const other = new KeyboardEvent("keydown", { key: "c", bubbles: true, cancelable: true, ctrlKey: true });
-    pre.dispatchEvent(other);
-    expect(other.defaultPrevented).toBe(false);
     expect(window.getSelection()?.rangeCount ?? 0).toBe(0);
   });
 
@@ -144,3 +172,137 @@ describe("SqlPreviewPanel select all", () => {
     expect(bubbled).toHaveBeenCalledOnce();
   });
 });
+
+describe("SqlPreviewPanel copy", () => {
+  it("copies a Ctrl+A selection through the app clipboard instead of the unreliable native path", async () => {
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+
+    pre.focus();
+    expect(dispatchSelectAll(pre).defaultPrevented).toBe(true);
+
+    const copied = dispatchCopy(pre);
+    await flushUi();
+
+    // The webview never lands a programmatically built selection on the system
+    // clipboard, which is why Ctrl+A followed by Ctrl+C used to toast success and
+    // copy nothing (#12167).
+    expect(copied.defaultPrevented).toBe(true);
+    expect(mocks.copyToClipboard).toHaveBeenCalledTimes(1);
+    expect(mocks.copyToClipboard).toHaveBeenCalledWith(SQL);
+    expect(mocks.toast).toHaveBeenCalledWith("grid.copied");
+  });
+
+  it("copies the whole preview when Ctrl+C arrives without a selection", async () => {
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+
+    const copied = dispatchCopy(pre);
+    await flushUi();
+
+    expect(copied.defaultPrevented).toBe(true);
+    expect(mocks.copyToClipboard).toHaveBeenCalledWith(SQL);
+    expect(mocks.toast).toHaveBeenCalledWith("grid.copied");
+  });
+
+  it("copies only the text the user actually highlighted", async () => {
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+
+    dragSelect(pre, 0, 7);
+    const copied = dispatchCopy(pre);
+    await flushUi();
+
+    expect(copied.defaultPrevented).toBe(true);
+    expect(mocks.copyToClipboard).toHaveBeenCalledTimes(1);
+    expect(mocks.copyToClipboard).toHaveBeenCalledWith(SQL.slice(0, 7));
+  });
+
+  it("copies only the highlighted SQL when the formatted view is active", async () => {
+    mocks.highlight.mockImplementation((content) => `<span class="tok">${content}</span>`);
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+    expect(pre.innerHTML).toContain('class="tok"');
+
+    dragSelect(pre.querySelector("span") ?? pre, 0, 7);
+    const copied = dispatchCopy(pre);
+    await flushUi();
+
+    expect(copied.defaultPrevented).toBe(true);
+    expect(mocks.copyToClipboard).toHaveBeenCalledWith(SQL.slice(0, 7));
+  });
+
+  it("supports Cmd+C on macOS", async () => {
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+
+    const copied = dispatchCopy(pre, { metaKey: true });
+    await flushUi();
+
+    expect(copied.defaultPrevented).toBe(true);
+    expect(mocks.copyToClipboard).toHaveBeenCalledWith(SQL);
+  });
+
+  it("falls back to the whole preview when the selection leaked outside it", async () => {
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+    const outside = document.createElement("div");
+    outside.textContent = "grid cell";
+    mounted.append(outside);
+    const outsideNode = outside.firstChild;
+    const previewNode = pre.firstChild;
+    if (!outsideNode || !previewNode) throw new Error("selection anchors not found");
+
+    const range = document.createRange();
+    range.setStart(previewNode, 0);
+    range.setEnd(outsideNode, 5);
+    const selection = window.getSelection();
+    selection?.removeAllRanges();
+    selection?.addRange(range);
+
+    const copied = dispatchCopy(pre);
+    await flushUi();
+    outside.remove();
+
+    expect(copied.defaultPrevented).toBe(true);
+    expect(mocks.copyToClipboard).toHaveBeenCalledWith(SQL);
+  });
+
+  it("keeps the shortcut untouched for other modifiers", async () => {
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+
+    expect(dispatchCopy(pre, { ctrlKey: true, shiftKey: true }).defaultPrevented).toBe(false);
+    expect(dispatchCopy(pre, { ctrlKey: true, altKey: true }).defaultPrevented).toBe(false);
+    expect(dispatchCopy(pre, { ctrlKey: false }).defaultPrevented).toBe(false);
+    expect(mocks.copyToClipboard).not.toHaveBeenCalled();
+    expect(mocks.toast).not.toHaveBeenCalled();
+  });
+
+  it("stops the copy shortcut from reaching the surrounding data grid", async () => {
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+    const bubbled = vi.fn();
+    mounted.addEventListener("keydown", bubbled);
+
+    const copied = dispatchCopy(pre);
+    await flushUi();
+
+    expect(copied.defaultPrevented).toBe(true);
+    expect(bubbled).not.toHaveBeenCalled();
+    expect(mocks.copyToClipboard).toHaveBeenCalledTimes(1);
+  });
+
+  it("surfaces a failure toast when the app clipboard rejects", async () => {
+    mocks.copyToClipboard.mockImplementationOnce(async () => {
+      throw new Error("clipboard unavailable");
+    });
+    const mounted = await mountPanel();
+    const pre = previewText(mounted);
+
+    dispatchCopy(pre);
+    await flushUi();
+
+    expect(mocks.toast.mock.calls[0]?.[0]).toBe("grid.copyFailed");
+  });
+});