diff --git a/lib/src/lib/terminal-mouse-router.test.ts b/lib/src/lib/terminal-mouse-router.test.ts
index 5923e2bd..65588963 100644
--- a/lib/src/lib/terminal-mouse-router.test.ts
+++ b/lib/src/lib/terminal-mouse-router.test.ts
@@ -330,4 +330,74 @@ describe('terminal-mouse-router: override suppression', () => {
     expect(getMouseSelectionState('t1').selection).toBeNull();
     cleanup();
   });
+
+  function mousePointer(overrides: Partial<PointerEvent> = {}): FakePointerEvent {
+    return pointerEvent({ pointerType: 'mouse', ...overrides });
+  }
+
+  // Drives a left-button mouse press into an active selection drag (capture +
+  // pendingDrag created on press, drag begun once movement crosses threshold).
+  function startMouseDrag(element: FakeElement) {
+    element.emit('pointerdown', mousePointer({ clientX: 5, clientY: 5 }));
+    element.emit('mousedown', mouseEvent({ clientX: 5, clientY: 5 }));
+    windowHost.emit('mousemove', mouseEvent({ clientX: 25, clientY: 15 }));
+  }
+
+  it('captures the mouse pointer on a left-button press over terminal-owned content', () => {
+    const { cleanup, element } = createHarness(windowHost);
+
+    element.emit('pointerdown', mousePointer({ clientX: 5, clientY: 5 }));
+
+    expect(element.setPointerCapture).toHaveBeenCalledWith(1);
+    cleanup();
+  });
+
+  it('does not capture the mouse pointer for non-left buttons', () => {
+    const { cleanup, element } = createHarness(windowHost);
+
+    element.emit('pointerdown', mousePointer({ button: 2 }));
+
+    expect(element.setPointerCapture).not.toHaveBeenCalled();
+    cleanup();
+  });
+
+  it('finalizes a mouse drag from a captured pointerup when the button is released outside the iframe', () => {
+    vi.useFakeTimers();
+    const { cleanup, element } = createHarness(windowHost);
+
+    startMouseDrag(element);
+    expect(getMouseSelectionState('t1').selection).toMatchObject({ dragging: true });
+
+    // Released outside the iframe: only the captured pointerup reaches us, never
+    // the compatibility mouseup. The deferred finalize ends the drag in place.
+    windowHost.emit('pointerup', mousePointer({ clientX: 500, clientY: 500 }));
+    expect(element.releasePointerCapture).toHaveBeenCalledWith(1);
+    expect(getMouseSelectionState('t1').selection).toMatchObject({ dragging: true });
+
+    vi.runAllTimers();
+    expect(getMouseSelectionState('t1').selection).toMatchObject({ dragging: false });
+
+    vi.useRealTimers();
+    cleanup();
+  });
+
+  it('lets the inside mouseup finalize and no-ops the deferred pointerup finalize', () => {
+    vi.useFakeTimers();
+    const { cleanup, element } = createHarness(windowHost);
+
+    startMouseDrag(element);
+
+    // Released inside: pointerup is followed by the compatibility mouseup, which
+    // finalizes through the normal path and cancels the deferred finalize.
+    windowHost.emit('pointerup', mousePointer({ clientX: 25, clientY: 15 }));
+    windowHost.emit('mouseup', mouseEvent({ clientX: 25, clientY: 15 }));
+    expect(getMouseSelectionState('t1').selection).toMatchObject({ dragging: false });
+
+    // The deferred finalize must be a harmless no-op now.
+    expect(() => vi.runAllTimers()).not.toThrow();
+    expect(getMouseSelectionState('t1').selection).toMatchObject({ dragging: false });
+
+    vi.useRealTimers();
+    cleanup();
+  });
 });
diff --git a/lib/src/lib/terminal-mouse-router.ts b/lib/src/lib/terminal-mouse-router.ts
index 1d396655..2962a15c 100644
--- a/lib/src/lib/terminal-mouse-router.ts
+++ b/lib/src/lib/terminal-mouse-router.ts
@@ -91,6 +91,14 @@ export function attachTerminalMouseRouter({
   let lastTouchTap: { time: number; x: number; y: number } | null = null;
   // True while the active drag is block-mode (Alt on desktop, double-tap on touch).
   let dragBlock = false;
+  // Set while we hold pointer capture for a mouse drag. Chromium delivers the
+  // captured pointerup across the iframe boundary even when the button is
+  // released over the host page, which lets us finalize an outside release at
+  // once instead of waiting for the window-mousemove heal.
+  let mouseDragPointerId: number | null = null;
+  // True between a captured mouse pointerup we saw and the compatibility mouseup
+  // we expect to follow it for an *inside* release; see onWindowPointerUp.
+  let awaitingOutsideMouseUp = false;
 
   const terminalOwnsEvent = (ev: MouseEvent | PointerEvent) => {
     const state = getMouseSelectionState(id);
@@ -208,7 +216,26 @@ export function attachTerminalMouseRouter({
   };
 
   const onPointerDown = (ev: PointerEvent) => {
-    if (ev.pointerType === 'mouse') return;
+    if (ev.pointerType === 'mouse') {
+      // Capture the mouse pointer for left-button presses on terminal-owned
+      // content so a selection drag released *outside* our iframe still reports
+      // back. Chromium delivers the captured pointerup across the frame boundary
+      // even when the button comes up over the host page, letting onWindowPointerUp
+      // finalize the drag immediately rather than waiting for the cursor to wander
+      // back in (the window-mousemove heal). Engines that don't honor cross-frame
+      // capture get no such pointerup and fall back to that heal.
+      if (ev.button !== 0) return;
+      const { terminalOwns } = terminalOwnsEvent(ev);
+      if (!terminalOwns) return;
+      try {
+        element.setPointerCapture(ev.pointerId);
+        mouseDragPointerId = ev.pointerId;
+      } catch {
+        // Best-effort continuity aid; the heal still covers us if capture is rejected.
+        mouseDragPointerId = null;
+      }
+      return;
+    }
     if (!ev.isPrimary) return;
     // Double-tap = this press lands soon after, and near, the previous touch that
     // ended as a tap. Recording only on a tap release (not on a drag) keeps two
@@ -241,10 +268,25 @@ export function attachTerminalMouseRouter({
   };
 
   const onWindowMouseMove = (ev: MouseEvent) => {
+    // Backstop for engines that don't deliver a cross-frame captured pointerup
+    // (see onPointerDown). A mouse drag is otherwise kept alive only by the
+    // window 'mouseup' below, and when the button is released outside our iframe
+    // that mouseup is delivered to the host document and never reaches us,
+    // leaving the drag stuck. The next move we see (e.g. when the pointer
+    // re-enters) reports no buttons held — treat that as the mouseup we missed
+    // and finalize the drag in place. A genuine drag that leaves and re-enters
+    // still holding the button reports buttons===1, so this never fires mid-drag.
+    if (ev.buttons === 0 && (pendingDrag || isDragging(id))) {
+      finishPendingOrActiveDrag(ev);
+      return;
+    }
     updatePendingOrActiveDrag(ev);
   };
 
   const onWindowMouseUp = (ev: MouseEvent) => {
+    // The button came up inside the iframe; cancel any pending outside-release
+    // finalize (see onWindowPointerUp) and end the drag through the normal path.
+    awaitingOutsideMouseUp = false;
     finishPendingOrActiveDrag(ev);
   };
 
@@ -255,7 +297,32 @@ export function attachTerminalMouseRouter({
   };
 
   const onWindowPointerUp = (ev: PointerEvent) => {
-    if (ev.pointerType === 'mouse') return;
+    if (ev.pointerType === 'mouse') {
+      if (mouseDragPointerId !== ev.pointerId) return;
+      mouseDragPointerId = null;
+      // Capture auto-releases on pointerup, but be explicit.
+      try {
+        element.releasePointerCapture(ev.pointerId);
+      } catch {
+        // already released
+      }
+      if (!(pendingDrag || isDragging(id))) return;
+      // Defer to a macrotask, not a microtask: the compatibility mouseup for an
+      // inside release is dispatched in this same task (right after this
+      // pointerup), and a microtask would run before it. If that mouseup
+      // arrives, onWindowMouseUp finalizes through the established path and
+      // clears this flag; only when it doesn't — the button was released outside
+      // the iframe, where Chromium still delivers this captured pointerup — do we
+      // finalize here.
+      awaitingOutsideMouseUp = true;
+      const releaseEvent = ev;
+      setTimeout(() => {
+        if (!awaitingOutsideMouseUp) return;
+        awaitingOutsideMouseUp = false;
+        finishPendingOrActiveDrag(releaseEvent);
+      }, 0);
+      return;
+    }
     if (activePointerId !== ev.pointerId) return;
     finishPendingOrActiveDrag(ev);
     activePointerId = null;
diff --git a/scripts/dogfood-vscode.mjs b/scripts/dogfood-vscode.mjs
new file mode 100644
index 00000000..58430cca
--- /dev/null
+++ b/scripts/dogfood-vscode.mjs
@@ -0,0 +1,32 @@
+import { spawnSync } from 'node:child_process';
+import { rmSync } from 'node:fs';
+import { dirname, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const scriptDir = dirname(fileURLToPath(import.meta.url));
+const extDir = resolve(scriptDir, '..', 'vscode-ext');
+const vsix = resolve(extDir, 'dormouse.vsix');
+
+// The VS Code CLI emits internal Node deprecation warnings (e.g. DEP0169);
+// silence them so dogfood output stays focused on what matters.
+const codeEnv = { ...process.env, NODE_NO_WARNINGS: '1' };
+
+// `code` and `pnpm` are `.cmd` shims on Windows, so run through a shell to
+// resolve them on PATH. Args are static and shell-safe.
+function run(command, { ignoreFailure = false, stdio = 'inherit', env = process.env } = {}) {
+  const result = spawnSync(command, { cwd: extDir, stdio, shell: true, env });
+  if (!ignoreFailure && result.status !== 0) {
+    process.exit(result.status ?? 1);
+  }
+  return result;
+}
+
+// Remove the legacy extension if present; ignore failure when it isn't installed.
+run('code --uninstall-extension diffplug.mouseterm', { ignoreFailure: true, stdio: 'ignore', env: codeEnv });
+
+run('pnpm package');
+run('code --install-extension dormouse.vsix --force', { env: codeEnv });
+
+rmSync(vsix, { force: true });
+
+console.log('Reload VSCode window (Cmd+Shift+P then Reload Window) to pick up the new extension.');
diff --git a/vscode-ext/package.json b/vscode-ext/package.json
index e9bb77f8..c38e902b 100644
--- a/vscode-ext/package.json
+++ b/vscode-ext/package.json
@@ -105,7 +105,7 @@
     "stage:dor-cli": "pnpm --filter dor build && node ../scripts/stage-dor-cli.mjs vscode-ext/dor-cli",
     "watch": "pnpm build --watch",
     "package": "vsce package --no-dependencies --out dormouse.vsix",
-    "dogfood": "code --uninstall-extension diffplug.mouseterm >/dev/null 2>&1 || true; pnpm package && code --install-extension dormouse.vsix --force && rm -f dormouse.vsix && echo '\\n✦ Reload VSCode window (Cmd+Shift+P → Reload Window) to pick up the new extension.'",
+    "dogfood": "node ../scripts/dogfood-vscode.mjs",
     "publish:marketplace": "vsce publish --no-dependencies",
     "publish:openvsx": "ovsx publish --no-dependencies"
   },