diff --git a/frontend/src/core/components/shared/Tooltip.tsx b/frontend/src/core/components/shared/Tooltip.tsx
index 10fefec02..2580b3530 100644
--- a/frontend/src/core/components/shared/Tooltip.tsx
+++ b/frontend/src/core/components/shared/Tooltip.tsx
@@ -83,7 +83,10 @@ export const Tooltip: React.FC<TooltipProps> = ({
     }
   }, []);
 
-  const sidebarContext = sidebarTooltip ? useSidebarContext() : null;
+  // Always call the hook unconditionally to satisfy React's rules of hooks.
+  // The context is only used when sidebarTooltip is true.
+  const sidebarContextValue = useSidebarContext();
+  const sidebarContext = sidebarTooltip ? sidebarContextValue : null;
 
   const isControlled = controlledOpen !== undefined;
   const open = (isControlled ? !!controlledOpen : internalOpen) && !disabled;
diff --git a/frontend/src/core/components/shared/rightRail/ViewerAnnotationControls.tsx b/frontend/src/core/components/shared/rightRail/ViewerAnnotationControls.tsx
index 54eec53f9..f4bbb386f 100644
--- a/frontend/src/core/components/shared/rightRail/ViewerAnnotationControls.tsx
+++ b/frontend/src/core/components/shared/rightRail/ViewerAnnotationControls.tsx
@@ -55,11 +55,6 @@ export default function ViewerAnnotationControls({ currentView, disabled = false
   const isAnnotateActive = selectedTool === 'annotate';
   const annotationsHidden = viewerContext ? !viewerContext.isAnnotationsVisible : false;
 
-  // Don't show any annotation controls in sign mode
-  if (isSignMode) {
-    return null;
-  }
-
   // Persist annotations to file if there are unsaved changes
   const saveAnnotationsIfNeeded = async () => {
     if (!viewerContext?.exportActions?.saveAsCopy || currentView !== 'viewer' || !historyApiRef?.current?.canUndo()) return;
@@ -135,6 +130,11 @@ export default function ViewerAnnotationControls({ currentView, disabled = false
     }
   };
 
+  // Don't show any annotation controls in sign mode
+  // NOTE: This early return is placed AFTER all hooks to satisfy React's rules of hooks
+  if (isSignMode) {
+    return null;
+  }
 
   return (
     <>
diff --git a/frontend/src/core/contexts/FileContext.tsx b/frontend/src/core/contexts/FileContext.tsx
index 378d43050..f63ae0f69 100644
--- a/frontend/src/core/contexts/FileContext.tsx
+++ b/frontend/src/core/contexts/FileContext.tsx
@@ -54,8 +54,10 @@ function FileContextInner({
 }: FileContextProviderProps) {
   const [state, dispatch] = useReducer(fileContextReducer, initialFileContextState);
 
-  // IndexedDB context for persistence
-  const indexedDB = enablePersistence ? useIndexedDB() : null;
+  // Always call the hook unconditionally to satisfy React's rules of hooks.
+  // IndexedDB context is only used when enablePersistence is true.
+  const indexedDBValue = useIndexedDB();
+  const indexedDB = enablePersistence ? indexedDBValue : null;
 
   // File ref map - stores File objects outside React state
   const filesRef = useRef<Map<FileId, File>>(new Map());