diff --git a/docs/floating-ai-integration-guide.md b/docs/floating-ai-integration-guide.md
index 0a2ee73..64f3b68 100644
--- a/docs/floating-ai-integration-guide.md
+++ b/docs/floating-ai-integration-guide.md
@@ -355,7 +355,7 @@ return (
 
 ## Step 3: Create Double-Click Hook
 
-**Status**: [ ]
+**Status**: [x] 2026-02-27
 **Prerequisites**: Step 2 completed
 **Creates**: `src/renderer/hooks/useDoubleClickAI.ts`
 **Modifies**: `src/renderer/components/layout/AppShell.tsx` (add hook call)
diff --git a/src/renderer/components/layout/AppShell.tsx b/src/renderer/components/layout/AppShell.tsx
index 9822937..f8e7512 100644
--- a/src/renderer/components/layout/AppShell.tsx
+++ b/src/renderer/components/layout/AppShell.tsx
@@ -18,6 +18,7 @@ import {
   Palette
 } from 'lucide-react';
 import { trpc } from '@/lib/trpc';
+import { useDoubleClickAI } from '@/hooks/useDoubleClickAI';
 import {
   Sidebar,
   SidebarContent,
@@ -84,6 +85,16 @@ function findScrollableAncestor(el: Element | null): Element | null {
 }
 
 export function AppShell({ children }: AppShellProps) {
+  return (
+    <FloatingChatProvider>
+      <AppShellInner>{children}</AppShellInner>
+    </FloatingChatProvider>
+  );
+}
+
+function AppShellInner({ children }: AppShellProps) {
+  useDoubleClickAI();
+
   const collapsedQuery = trpc.settings.getSidebarCollapsed.useQuery(undefined, {
     staleTime: Infinity,
   });
@@ -209,7 +220,6 @@ export function AppShell({ children }: AppShellProps) {
   }, [openCurtain, closeCurtain]);
 
   return (
-    <FloatingChatProvider>
     <>
     <SidebarProvider open={open} onOpenChange={handleOpenChange}>
       <AppSidebar
@@ -301,7 +311,6 @@ export function AppShell({ children }: AppShellProps) {
       </DialogContent>
     </Dialog>
     </>
-    </FloatingChatProvider>
   );
 }
 
diff --git a/src/renderer/hooks/useDoubleClickAI.ts b/src/renderer/hooks/useDoubleClickAI.ts
new file mode 100644
index 0000000..d8593e0
--- /dev/null
+++ b/src/renderer/hooks/useDoubleClickAI.ts
@@ -0,0 +1,44 @@
+import { useEffect } from 'react';
+import { useFloatingChat } from '@/context/FloatingChatContext';
+
+// Elements where double-click should NOT trigger the AI popup
+const INTERACTIVE_TAGS = new Set(['INPUT', 'TEXTAREA', 'SELECT']);
+
+export function useDoubleClickAI(): void {
+  const { openAtSection, state } = useFloatingChat();
+
+  useEffect(() => {
+    const handler = (e: MouseEvent) => {
+      const target = e.target as HTMLElement;
+
+      // Skip interactive elements (preserve text selection behavior)
+      if (INTERACTIVE_TAGS.has(target.tagName)) return;
+
+      // Skip contenteditable elements UNLESS they're inside Milkdown
+      if (target.isContentEditable) {
+        const inMilkdown =
+          target.closest('.milkdown-container') ||
+          target.closest('.crepe-editor');
+        if (!inMilkdown) return;
+        // For Milkdown: only trigger if no text was selected by the double-click
+        const selection = window.getSelection();
+        if (selection && selection.toString().trim().length > 0) return;
+      }
+
+      // Walk up DOM to find nearest [data-ai-section]
+      const sectionEl = (target as Element).closest('[data-ai-section]');
+      if (!sectionEl) return;
+
+      const sectionId = sectionEl.getAttribute('data-ai-section');
+      if (!sectionId) return;
+
+      // If popup is already open at THIS section, do nothing
+      if (state.isOpen && state.activeSectionId === sectionId) return;
+
+      openAtSection(sectionId);
+    };
+
+    document.addEventListener('dblclick', handler);
+    return () => document.removeEventListener('dblclick', handler);
+  }, [openAtSection, state.isOpen, state.activeSectionId]);
+}