diff --git a/src/components/Feed.tsx b/src/components/Feed.tsx
index 3c3bad50..5cc31e5e 100644
--- a/src/components/Feed.tsx
+++ b/src/components/Feed.tsx
@@ -1,4 +1,4 @@
-import { useState, useEffect, useMemo, useCallback } from 'react';
+import { useState, useEffect, useMemo, useCallback, useRef } from 'react';
 import { useInView } from 'react-intersection-observer';
 import { useQueryClient } from '@tanstack/react-query';
 import { ComposeBox } from '@/components/ComposeBox';
@@ -15,6 +15,7 @@ import { useInfiniteSortedPosts } from '@/hooks/useTrending';
 import { useCurrentUser } from '@/hooks/useCurrentUser';
 import { useMuteList } from '@/hooks/useMuteList';
 import { isEventMuted } from '@/lib/muteHelpers';
+import { useSetFabHidden } from '@/contexts/LayoutContext';
 import { cn } from '@/lib/utils';
 import type { FeedItem } from '@/lib/feedUtils';
 
@@ -38,6 +39,23 @@ export function Feed({ kinds, tagFilters, header, hideCompose, emptyMessage }: F
   const { user } = useCurrentUser();
   const { muteItems } = useMuteList();
   const queryClient = useQueryClient();
+  const setFabHidden = useSetFabHidden();
+
+  // Hide FAB while the ComposeBox is visible in the viewport
+  const composeRef = useRef<HTMLDivElement>(null);
+  useEffect(() => {
+    const el = composeRef.current;
+    if (!el || hideCompose) return;
+    const observer = new IntersectionObserver(
+      ([entry]) => setFabHidden(entry.isIntersecting),
+      { threshold: 0 },
+    );
+    observer.observe(el);
+    return () => {
+      observer.disconnect();
+      setFabHidden(false); // restore FAB when Feed unmounts
+    };
+  }, [hideCompose, setFabHidden]);
 
   // Tab settings from localStorage
   const showGlobalFeed = (() => {
@@ -160,7 +178,7 @@ export function Feed({ kinds, tagFilters, header, hideCompose, emptyMessage }: F
 
   return (
     <main className="flex-1 min-w-0">
-      {!hideCompose && <ComposeBox compact />}
+      {!hideCompose && <div ref={composeRef}><ComposeBox compact /></div>}
 
       {header}
 
diff --git a/src/components/MainLayout.tsx b/src/components/MainLayout.tsx
index 9828497c..3bba1595 100644
--- a/src/components/MainLayout.tsx
+++ b/src/components/MainLayout.tsx
@@ -64,7 +64,7 @@ function PageSkeleton() {
 
 /** Inner component that reads layout options from the context store. */
 function MainLayoutInner() {
-  const { rightSidebar, showFAB = false, fabKind = 1, fabHref, onFabClick, noBottomSpacer = false, wrapperClassName } = useLayoutSnapshot();
+  const { rightSidebar, showFAB = false, fabKind = 1, fabHref, onFabClick, noBottomSpacer = false, wrapperClassName, fabHidden } = useLayoutSnapshot();
   const [drawerOpen, setDrawerOpen] = useState(false);
   const { config } = useAppContext();
 
@@ -92,8 +92,11 @@ function MainLayoutInner() {
           <div className={cn("relative flex-1 min-w-0 sidebar:max-w-[600px] sidebar:border-l border-r border-border bg-background/85")}>
             <Outlet />
             {showFAB && (
-              <div className="sticky bottom-fab sidebar:bottom-6 z-30 pointer-events-none flex justify-end pr-6">
-                <div className="pointer-events-auto">
+              <div className={cn(
+                'sticky bottom-fab sidebar:bottom-6 z-30 pointer-events-none flex justify-end pr-6 transition-all duration-300',
+                fabHidden ? 'opacity-0 translate-y-4' : 'opacity-100 translate-y-0',
+              )}>
+                <div className={cn('pointer-events-auto', fabHidden && 'pointer-events-none')}>
                   <FloatingComposeButton kind={fabKind} href={fabHref} onFabClick={onFabClick} />
                 </div>
               </div>
diff --git a/src/contexts/LayoutContext.ts b/src/contexts/LayoutContext.ts
index 444d919d..f82bece5 100644
--- a/src/contexts/LayoutContext.ts
+++ b/src/contexts/LayoutContext.ts
@@ -26,11 +26,22 @@ const EMPTY: LayoutOptions = {};
  * A mutable store that holds the current layout options.
  * Pages call `setOptions` to update, and MainLayout subscribes via useSyncExternalStore.
  */
+/** Snapshot returned by the layout store, combining page options with dynamic state. */
+export type LayoutSnapshot = LayoutOptions & { fabHidden: boolean };
+
+const EMPTY_SNAPSHOT: LayoutSnapshot = { fabHidden: false };
+
 export class LayoutStore {
   private options: LayoutOptions = EMPTY;
+  private _fabHidden = false;
+  private _snapshot: LayoutSnapshot = EMPTY_SNAPSHOT;
   private listeners = new Set<Listener>();
 
-  getSnapshot = (): LayoutOptions => this.options;
+  private buildSnapshot(): void {
+    this._snapshot = { ...this.options, fabHidden: this._fabHidden };
+  }
+
+  getSnapshot = (): LayoutSnapshot => this._snapshot;
 
   subscribe = (listener: Listener): (() => void) => {
     this.listeners.add(listener);
@@ -40,12 +51,22 @@ export class LayoutStore {
   setOptions = (next: LayoutOptions): void => {
     if (this.options === next) return;
     this.options = next;
+    this.buildSnapshot();
+    this.listeners.forEach((l) => l());
+  };
+
+  setFabHidden = (hidden: boolean): void => {
+    if (this._fabHidden === hidden) return;
+    this._fabHidden = hidden;
+    this.buildSnapshot();
     this.listeners.forEach((l) => l());
   };
 
   reset = (): void => {
-    if (this.options === EMPTY) return;
+    if (this.options === EMPTY && !this._fabHidden) return;
     this.options = EMPTY;
+    this._fabHidden = false;
+    this._snapshot = EMPTY_SNAPSHOT;
     this.listeners.forEach((l) => l());
   };
 }
@@ -101,7 +122,13 @@ export function useLayoutOptions(options: LayoutOptions): void {
 }
 
 /** Hook for MainLayout to read the current layout options reactively. */
-export function useLayoutSnapshot(): LayoutOptions {
+export function useLayoutSnapshot(): LayoutSnapshot {
   const store = useLayoutStore();
   return useSyncExternalStore(store.subscribe, store.getSnapshot, store.getSnapshot);
 }
+
+/** Hook for components to signal that the FAB should be hidden (e.g., ComposeBox is visible). */
+export function useSetFabHidden(): (hidden: boolean) => void {
+  const store = useLayoutStore();
+  return store.setFabHidden;
+}