diff --git a/desktop/src/components/composite/OpenWithMenu.test.tsx b/desktop/src/components/composite/OpenWithMenu.test.tsx
index 0a8103c4..456d6842 100644
--- a/desktop/src/components/composite/OpenWithMenu.test.tsx
+++ b/desktop/src/components/composite/OpenWithMenu.test.tsx
@@ -1,10 +1,17 @@
 import '@testing-library/jest-dom'
 import { fireEvent, render, screen } from '@testing-library/react'
-import { describe, expect, it, vi } from 'vitest'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 import { OpenWithMenu } from './OpenWithMenu'
 import type { OpenWithItem } from '../../lib/openWithItems'
 
 const anchor = { top: 100, bottom: 110, left: 20, right: 120 }
+const originalViewport = { width: window.innerWidth, height: window.innerHeight }
+
+afterEach(() => {
+  Object.defineProperty(window, 'innerWidth', { value: originalViewport.width, configurable: true })
+  Object.defineProperty(window, 'innerHeight', { value: originalViewport.height, configurable: true })
+  vi.restoreAllMocks()
+})
 
 function makeItems(onSelect1 = vi.fn(), onSelect2 = vi.fn(), onSelect3 = vi.fn()): OpenWithItem[] {
   return [
@@ -76,6 +83,34 @@ describe('OpenWithMenu', () => {
     expect(onClose).toHaveBeenCalledTimes(1)
   })
 
+  it('aligns its right edge with the anchor to avoid a right-side native preview', () => {
+    Object.defineProperty(window, 'innerWidth', { value: 1200, configurable: true })
+    vi.spyOn(HTMLElement.prototype, 'getBoundingClientRect').mockReturnValue({
+      height: 160, width: 300, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0, toJSON: () => ({}),
+    } as DOMRect)
+    const rightEdge = 900
+
+    render(<OpenWithMenu items={makeItems()} anchor={{ top: 100, bottom: 110, left: 700, right: rightEdge }} onClose={vi.fn()} />)
+
+    const menu = screen.getByRole('menu')
+    expect(menu.style.left).toBe('600px')
+    expect(Number.parseFloat(menu.style.left) + 300).toBe(rightEdge)
+    expect(menu.className).toContain('max-w-[min(300px,calc(100vw-16px))]')
+  })
+
+  it('keeps a left-shifted menu inside the compact chat column', () => {
+    Object.defineProperty(window, 'innerWidth', { value: 1000, configurable: true })
+    vi.spyOn(HTMLElement.prototype, 'getBoundingClientRect').mockReturnValue({
+      height: 160, width: 300, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0, toJSON: () => ({}),
+    } as DOMRect)
+
+    render(<OpenWithMenu items={makeItems()} anchor={{ top: 100, bottom: 110, left: 40, right: 100 }} onClose={vi.fn()} />)
+
+    const menuLeft = Number.parseFloat(screen.getByRole('menu').style.left)
+    expect(menuLeft).toBe(8)
+    expect(menuLeft + 300).toBeLessThan(320)
+  })
+
   describe('triggerEl exclusion (re-click-trigger toggle support)', () => {
     it('does NOT call onClose when mousedown lands inside triggerEl', () => {
       // Set up a trigger element + a child within it in the document.
@@ -139,13 +174,12 @@ describe('OpenWithMenu', () => {
     // The trigger often sits right above the composer; the menu must not render off-screen below it.
     Object.defineProperty(window, 'innerHeight', { value: 300, configurable: true })
     Object.defineProperty(window, 'innerWidth', { value: 1000, configurable: true })
-    const rectSpy = vi.spyOn(HTMLElement.prototype, 'getBoundingClientRect').mockReturnValue({
+    vi.spyOn(HTMLElement.prototype, 'getBoundingClientRect').mockReturnValue({
       height: 200, width: 220, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0, toJSON: () => ({}),
     } as DOMRect)
     // anchor near the bottom: top:260/bottom:270. Down would be 276, 276+200=476 > 300-8 ⇒ flip up.
     render(<OpenWithMenu items={makeItems()} anchor={{ top: 260, bottom: 270, left: 20, right: 120 }} onClose={vi.fn()} />)
     // flipped top = anchor.top - height - 6 = 260 - 200 - 6 = 54
     expect(screen.getByRole('menu').style.top).toBe('54px')
-    rectSpy.mockRestore()
   })
 })
diff --git a/desktop/src/components/composite/OpenWithMenu.tsx b/desktop/src/components/composite/OpenWithMenu.tsx
index 7c169988..40e2f89c 100644
--- a/desktop/src/components/composite/OpenWithMenu.tsx
+++ b/desktop/src/components/composite/OpenWithMenu.tsx
@@ -1,6 +1,7 @@
 import { createPortal } from 'react-dom'
-import { useCallback, useLayoutEffect, useRef, useState } from 'react'
+import { useCallback, useRef } from 'react'
 import { Globe, ExternalLink, FileText, Copy } from 'lucide-react'
+import { useAnchoredPosition } from '@/hooks/useAnchoredPosition'
 import { useDismissable } from '@/hooks/useDismissable'
 import { TargetIcon } from './TargetIcon'
 import type { OpenWithItem } from '../../lib/openWithItems'
@@ -23,34 +24,14 @@ function ItemIcon({ item }: { item: OpenWithItem }) {
   return <ExternalLink size={18} strokeWidth={1.9} />
 }
 
-const MARGIN = 8
-
 export function OpenWithMenu({ items, anchor, onClose, triggerEl }: Props) {
   const ref = useRef<HTMLDivElement>(null)
-  // Initial guess; corrected (before paint) by the layout effect once we can measure the menu.
-  const [pos, setPos] = useState<{ top: number; left: number }>(() => ({
-    top: anchor.bottom + 6,
-    left: Math.max(MARGIN, Math.min(anchor.left, window.innerWidth - 240 - MARGIN)),
-  }))
-
-  // Position viewport-aware: flip above the anchor if it would overflow the bottom
-  // (the trigger often sits right above the composer), and clamp into the viewport.
-  useLayoutEffect(() => {
-    const el = ref.current
-    if (!el) return
-    const { height, width } = el.getBoundingClientRect()
-    const vh = window.innerHeight
-    const vw = window.innerWidth
-
-    let top = anchor.bottom + 6
-    if (height > 0 && top + height > vh - MARGIN) {
-      const flipped = anchor.top - height - 6
-      top = flipped >= MARGIN ? flipped : Math.max(MARGIN, vh - height - MARGIN)
-    }
-    let left = anchor.left
-    if (width > 0) left = Math.max(MARGIN, Math.min(left, vw - width - MARGIN))
-    setPos({ top, left })
-  }, [anchor])
+  const { style: positionStyle } = useAnchoredPosition({
+    open: true,
+    anchorRect: anchor,
+    floatingRef: ref,
+    placement: 'bottom-end',
+  })
 
   // The hook takes a ref; this component is handed the raw trigger element by
   // its callers. Only the dismiss handler reads it, and it does so at event
@@ -77,8 +58,8 @@ export function OpenWithMenu({ items, anchor, onClose, triggerEl }: Props) {
     <div
       ref={ref}
       role="menu"
-      className="fixed min-w-[220px] overflow-hidden rounded-[12px] border border-[var(--color-border)] bg-[var(--color-surface)] py-1 shadow-[var(--shadow-dropdown)]"
-      style={{ top: pos.top, left: pos.left, zIndex: 'var(--z-dropdown)' }}
+      className="min-w-[min(220px,calc(100vw-16px))] max-w-[min(300px,calc(100vw-16px))] overflow-hidden rounded-[12px] border border-[var(--color-border)] bg-[var(--color-surface)] py-1 shadow-[var(--shadow-dropdown)]"
+      style={{ ...positionStyle, zIndex: 'var(--z-dropdown)' }}
     >
       {items.map((item) => (
         <button
diff --git a/desktop/src/hooks/useAnchoredPosition.test.tsx b/desktop/src/hooks/useAnchoredPosition.test.tsx
index 219adb88..11160428 100644
--- a/desktop/src/hooks/useAnchoredPosition.test.tsx
+++ b/desktop/src/hooks/useAnchoredPosition.test.tsx
@@ -98,6 +98,32 @@ describe('useAnchoredPosition', () => {
     expect(result.style.left).toBe(120)
   })
 
+  it('positions from snapshot anchor geometry', () => {
+    const captured: { current: Result | null } = { current: null }
+
+    function Harness() {
+      const floatingRef = useRef<HTMLDivElement | null>(null)
+      captured.current = useAnchoredPosition({
+        open: true,
+        anchorRect: { top: 100, bottom: 130, left: 200, right: 300 },
+        floatingRef,
+        placement: 'bottom-end',
+      })
+      return (
+        <div
+          ref={(element) => {
+            floatingRef.current = element
+            if (element) stubRect(element, { width: 180, height: 120 })
+          }}
+        />
+      )
+    }
+
+    render(<Harness />)
+    expect(captured.current!.style.top).toBe(136)
+    expect(captured.current!.style.left).toBe(120)
+  })
+
   it('flips above the anchor when it would overflow the bottom', () => {
     const result = renderAnchored({
       anchor: { top: 700, bottom: 740, left: 200, right: 300 },
diff --git a/desktop/src/hooks/useAnchoredPosition.ts b/desktop/src/hooks/useAnchoredPosition.ts
index 5381365b..8f229217 100644
--- a/desktop/src/hooks/useAnchoredPosition.ts
+++ b/desktop/src/hooks/useAnchoredPosition.ts
@@ -2,9 +2,14 @@ import { useCallback, useLayoutEffect, useState, type CSSProperties } from 'reac
 
 export type AnchoredPlacement = 'bottom-start' | 'bottom-end' | 'top-start' | 'top-end'
 
-export type UseAnchoredPositionOptions = {
+export type AnchoredRect = Pick<DOMRect, 'top' | 'right' | 'bottom' | 'left'>
+
+type AnchorSource =
+  | { anchorRef: { current: HTMLElement | null }; anchorRect?: never }
+  | { anchorRef?: never; anchorRect: AnchoredRect }
+
+export type UseAnchoredPositionOptions = AnchorSource & {
   open: boolean
-  anchorRef: { current: HTMLElement | null }
   floatingRef: { current: HTMLElement | null }
   placement?: AnchoredPlacement
   /** Gap between anchor and overlay, in pixels. */
@@ -42,6 +47,7 @@ const DEFAULT_MARGIN = 8
 export function useAnchoredPosition({
   open,
   anchorRef,
+  anchorRect,
   floatingRef,
   placement = 'bottom-start',
   offset = 6,
@@ -54,11 +60,10 @@ export function useAnchoredPosition({
   )
 
   const measure = useCallback(() => {
-    const anchor = anchorRef.current
+    const anchorBox = anchorRect ?? anchorRef?.current?.getBoundingClientRect()
     const floating = floatingRef.current
-    if (!anchor || !floating) return
+    if (!anchorBox || !floating) return
 
-    const anchorBox = anchor.getBoundingClientRect()
     const { width, height } = floating.getBoundingClientRect()
     const viewportWidth = window.innerWidth
     const viewportHeight = window.innerHeight
@@ -98,7 +103,19 @@ export function useAnchoredPosition({
     }
 
     setState({ top, left, placement: resolved, ready: true })
-  }, [anchorRef, floatingRef, placement, offset, viewportMargin, flip, shift])
+  }, [
+    anchorRect?.top,
+    anchorRect?.right,
+    anchorRect?.bottom,
+    anchorRect?.left,
+    anchorRef,
+    floatingRef,
+    placement,
+    offset,
+    viewportMargin,
+    flip,
+    shift,
+  ])
 
   useLayoutEffect(() => {
     if (!open) {