diff --git a/engine/src/parser/pdfium_document.cpp b/engine/src/parser/pdfium_document.cpp
index bb3dff0..cc4c9af 100644
--- a/engine/src/parser/pdfium_document.cpp
+++ b/engine/src/parser/pdfium_document.cpp
@@ -2250,6 +2250,92 @@ std::expected<void, EngineError> PdfiumDocument::applyEdits(const std::string& e
                     spdlog::warn("delete_annotation: annotation '{}' not found on page {}", targetId, pageIndex);
                 }
                 FPDF_ClosePage(page);
+            } else if (type == "update_annotation") {
+                if (!op.contains("data") || !op["data"].is_object()) {
+                    spdlog::error("update_annotation operation missing 'data' object");
+                    return std::unexpected(EngineError::InvalidFormat);
+                }
+                auto data = op["data"];
+                std::string targetId = data.value("annotationId", "");
+                if (targetId.empty()) {
+                    spdlog::error("update_annotation missing 'annotationId'");
+                    return std::unexpected(EngineError::InvalidFormat);
+                }
+
+                FPDF_PAGE page = FPDF_LoadPage(doc_, pageIndex);
+                if (!page) {
+                    spdlog::error("Failed to load page index {} for update_annotation", pageIndex);
+                    return std::unexpected(EngineError::Unknown);
+                }
+
+                int count = FPDFPage_GetAnnotCount(page);
+                FPDF_ANNOTATION targetAnnot = nullptr;
+                for (int i = 0; i < count; ++i) {
+                    FPDF_ANNOTATION annot = FPDFPage_GetAnnot(page, i);
+                    if (!annot) continue;
+
+                    std::string id;
+                    unsigned long len = FPDFAnnot_GetStringValue(annot, "NM", nullptr, 0);
+                    if (len > 2) {
+                        std::vector<uint8_t> buf(len);
+                        FPDFAnnot_GetStringValue(annot, "NM", reinterpret_cast<FPDF_WCHAR*>(buf.data()), len);
+                        id = utf16le_to_utf8(reinterpret_cast<const char16_t*>(buf.data()), len / sizeof(char16_t));
+                        while (!id.empty() && id.back() == '\0') id.pop_back();
+                    }
+                    if (id.empty()) {
+                        id = "anno_" + std::to_string(pageIndex) + "_" + std::to_string(i);
+                    }
+                    
+                    if (id == targetId) {
+                        targetAnnot = annot;
+                        break;
+                    }
+                    FPDFPage_CloseAnnot(annot);
+                }
+
+                if (targetAnnot) {
+                    // Update Rect
+                    if (data.contains("x") && data.contains("y") && data.contains("width") && data.contains("height")) {
+                        double pageHeight = FPDF_GetPageHeightF(page);
+                        float x = static_cast<float>(data["x"].get<double>());
+                        float y = static_cast<float>(data["y"].get<double>());
+                        float width = static_cast<float>(data["width"].get<double>());
+                        float height = static_cast<float>(data["height"].get<double>());
+
+                        FS_RECTF rect;
+                        rect.left = x;
+                        rect.right = x + width;
+                        rect.top = static_cast<float>(pageHeight - y);
+                        rect.bottom = static_cast<float>(pageHeight - (y + height));
+                        FPDFAnnot_SetRect(targetAnnot, &rect);
+                    }
+
+                    // Update Color
+                    if (data.contains("color")) {
+                        std::string colorStr = data["color"].get<std::string>();
+                        unsigned int r = 0, g = 0, b = 0;
+                        parseHexColor(colorStr, r, g, b);
+                        FPDFAnnot_SetColor(targetAnnot, FPDFANNOT_COLORTYPE_Color, r, g, b, 255);
+                    }
+
+                    // Update Thickness
+                    if (data.contains("thickness")) {
+                        float thickness = static_cast<float>(data["thickness"].get<double>());
+                        FPDFAnnot_SetBorder(targetAnnot, 0.0f, 0.0f, thickness);
+                    }
+
+                    // Update Text
+                    if (data.contains("text")) {
+                        std::string text = data["text"].get<std::string>();
+                        auto utf16 = utf8_to_utf16le(text);
+                        FPDFAnnot_SetStringValue(targetAnnot, "Contents", reinterpret_cast<FPDF_WIDESTRING>(utf16.data()));
+                    }
+
+                    FPDFPage_CloseAnnot(targetAnnot);
+                } else {
+                    spdlog::warn("update_annotation: annotation '{}' not found on page {}", targetId, pageIndex);
+                }
+                FPDF_ClosePage(page);
             } else {
                 spdlog::warn("Unsupported edit operation type: {}", type);
             }
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 810d2a0..1315da9 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -425,6 +425,24 @@ function App() {
     }], 'Annotation deleted');
   };
 
+  const handleUpdateAnnotation = (a: Annotation) => {
+    // Optimistically update
+    setAnnotations((prev) => prev.map((x) => x.id === a.id ? a : x));
+    applyOps([{
+      id: rid('updanno'), type: 'update_annotation', pageIndex: a.pageIndex ?? currentPage,
+      data: {
+        annotationId: a.id,
+        x: a.bbox.x,
+        y: a.bbox.y,
+        width: a.bbox.width,
+        height: a.bbox.height,
+        color: a.color,
+        thickness: a.thickness,
+        text: a.content,
+      },
+    }], 'Annotation updated');
+  };
+
   /* -------------------------------------------------------------- render */
   return (
     <div className="flex h-full w-full flex-col overflow-hidden bg-[#f1f2f4] text-[#18212e] antialiased">
@@ -504,6 +522,11 @@ function App() {
                 searchResults={searchResults}
                 searchCurrentMatch={searchCurrentMatch}
                 onAnnotationAdded={handleAnnotationAdded}
+                onAnnotationUpdate={handleUpdateAnnotation}
+                onAnnotationClick={(a) => {
+                  setInspectorTab('notes');
+                  if (!isInspectorOpen) setIsInspectorOpen(true);
+                }}
                 onPageVisible={setCurrentPage}
                 onRedactArea={handleRedactArea}
                 onPlaceText={handlePlaceText}
@@ -546,6 +569,7 @@ function App() {
             annotations={annotations}
             onNavigateAnnotation={navigateToAnnotation}
             onDeleteAnnotation={handleDeleteAnnotation}
+            onUpdateAnnotation={handleUpdateAnnotation}
             outline={outline}
             onNavigateOutline={(p) => viewerRef.current?.scrollToPage(p)}
             searchQuery={searchQuery}
diff --git a/frontend/src/components/InspectorPanel.tsx b/frontend/src/components/InspectorPanel.tsx
index e852cc2..7d17e82 100644
--- a/frontend/src/components/InspectorPanel.tsx
+++ b/frontend/src/components/InspectorPanel.tsx
@@ -30,6 +30,7 @@ interface InspectorPanelProps {
   annotations: Annotation[];
   onNavigateAnnotation: (a: Annotation) => void;
   onDeleteAnnotation: (a: Annotation) => void;
+  onUpdateAnnotation?: (a: Annotation) => void;
 
   outline: OutlineItem[];
   onNavigateOutline: (pageIndex: number) => void;
@@ -137,7 +138,7 @@ export const InspectorPanel: React.FC<InspectorPanelProps> = (p) => {
         {/* Body */}
         <div className="custom-scrollbar min-h-0 flex-1 overflow-y-auto">
           {p.activeTab === 'pages' && <PagesTab {...p} />}
-          {p.activeTab === 'notes' && <NotesTab annotations={p.annotations.filter((a) => a.type !== 'widget')} onNavigate={p.onNavigateAnnotation} onDelete={p.onDeleteAnnotation} />}
+          {p.activeTab === 'notes' && <NotesTab annotations={p.annotations.filter((a) => a.type !== 'widget')} onNavigate={p.onNavigateAnnotation} onDelete={p.onDeleteAnnotation} onUpdate={p.onUpdateAnnotation} />}
           {p.activeTab === 'search' && <SearchTab {...p} />}
           {p.activeTab === 'properties' && <PropertiesTab metadata={p.metadata} sizeBytes={p.sizeBytes} totalPages={p.totalPages} filename={selectedDoc?.filename} />}
           {p.activeTab === 'fonts' && <FontsTab fonts={p.fonts} />}
@@ -191,7 +192,7 @@ const PagesTab: React.FC<InspectorPanelProps> = (p) => {
   );
 };
 
-const NotesTab: React.FC<{ annotations: Annotation[]; onNavigate: (a: Annotation) => void; onDelete: (a: Annotation) => void }> = ({ annotations, onNavigate, onDelete }) => {
+const NotesTab: React.FC<{ annotations: Annotation[]; onNavigate: (a: Annotation) => void; onDelete: (a: Annotation) => void; onUpdate?: (a: Annotation) => void }> = ({ annotations, onNavigate, onDelete, onUpdate }) => {
   if (annotations.length === 0) {
     return <EmptyState icon={<NotesIcon size={30} />} title="No annotations yet"
       hint="Highlights, ink, and comments you add appear here." />;
@@ -209,6 +210,30 @@ const NotesTab: React.FC<{ annotations: Annotation[]; onNavigate: (a: Annotation
             {a.content && <p className="line-clamp-3 text-[12px] italic text-[#5b6573]">“{a.content}”</p>}
             <span className="text-[10px] font-medium text-[#98a1ad]">{a.author}</span>
           </CustomButton>
+          
+          {onUpdate && (a.type === 'highlight' || a.type === 'ink' || a.type === 'comment') && (
+            <div className="flex items-center gap-2 mt-1 px-1" onClick={e => e.stopPropagation()}>
+              <input
+                type="color"
+                value={a.color || (a.type === 'highlight' ? '#ffeb3b' : '#000000')}
+                onChange={e => onUpdate({ ...a, color: e.target.value })}
+                className="h-5 w-5 cursor-pointer rounded border border-gray-300 p-0"
+                title="Change Color"
+              />
+              {a.type === 'ink' && (
+                <input
+                  type="range"
+                  min="1"
+                  max="10"
+                  value={a.thickness || 2}
+                  onChange={e => onUpdate({ ...a, thickness: parseFloat(e.target.value) })}
+                  className="w-16"
+                  title="Change Thickness"
+                />
+              )}
+            </div>
+          )}
+
           <button
             title="Delete annotation"
             aria-label="Delete annotation"
diff --git a/frontend/src/lib/gatewayService.ts b/frontend/src/lib/gatewayService.ts
index 1da9bce..7175a69 100644
--- a/frontend/src/lib/gatewayService.ts
+++ b/frontend/src/lib/gatewayService.ts
@@ -184,12 +184,24 @@ export type EditOperationDataMap = {
   page_deletion: PageDeletionData;
   page_reorder: PageReorderData;
   delete_annotation: DeleteAnnotationData;
+  update_annotation: UpdateAnnotationData;
 };
 
 export interface DeleteAnnotationData {
   annotationId: string;
 }
 
+export interface UpdateAnnotationData {
+  annotationId: string;
+  x?: number;
+  y?: number;
+  width?: number;
+  height?: number;
+  color?: string;
+  thickness?: number;
+  text?: string;
+}
+
 export interface OutlineItem {
   title: string;
   pageIndex: number;
diff --git a/frontend/src/viewer/AnnotationLayer.tsx b/frontend/src/viewer/AnnotationLayer.tsx
index f8ca812..a591c4e 100644
--- a/frontend/src/viewer/AnnotationLayer.tsx
+++ b/frontend/src/viewer/AnnotationLayer.tsx
@@ -29,6 +29,7 @@ interface AnnotationLayerProps {
   zoom: number;
   annotations: Annotation[];
   onAnnotationClick?: (annotation: Annotation) => void;
+  onAnnotationUpdate?: (annotation: Annotation) => void;
   onFieldChange?: (id: string, value: string | boolean, pageIndex: number) => void;
 }
 
@@ -39,8 +40,47 @@ export const AnnotationLayer: React.FC<AnnotationLayerProps> = ({
   zoom,
   annotations,
   onAnnotationClick,
+  onAnnotationUpdate,
   onFieldChange,
 }) => {
+  const [draggingAnno, setDraggingAnno] = React.useState<string | null>(null);
+  const [dragStartPos, setDragStartPos] = React.useState({ x: 0, y: 0 });
+  const [dragOffset, setDragOffset] = React.useState({ x: 0, y: 0 });
+
+  const handlePointerDown = (e: React.PointerEvent, id: string) => {
+    e.stopPropagation();
+    setDraggingAnno(id);
+    setDragStartPos({ x: e.clientX, y: e.clientY });
+    setDragOffset({ x: 0, y: 0 });
+    (e.target as HTMLElement).setPointerCapture(e.pointerId);
+  };
+
+  const handlePointerMove = (e: React.PointerEvent, id: string) => {
+    if (draggingAnno !== id) return;
+    setDragOffset({
+      x: (e.clientX - dragStartPos.x) / zoom,
+      y: (e.clientY - dragStartPos.y) / zoom,
+    });
+  };
+
+  const handlePointerUp = (e: React.PointerEvent, anno: Annotation) => {
+    if (draggingAnno !== anno.id) return;
+    setDraggingAnno(null);
+    (e.target as HTMLElement).releasePointerCapture(e.pointerId);
+    
+    if (dragOffset.x !== 0 || dragOffset.y !== 0) {
+      onAnnotationUpdate?.({
+        ...anno,
+        bbox: {
+          ...anno.bbox,
+          x: anno.bbox.x + dragOffset.x,
+          y: anno.bbox.y + dragOffset.y,
+        }
+      });
+    } else {
+      onAnnotationClick?.(anno);
+    }
+  };
   return (
     <div
       className="absolute top-0 left-0 z-30"
@@ -62,17 +102,19 @@ export const AnnotationLayer: React.FC<AnnotationLayerProps> = ({
             ? `${anno.author}${formattedDate ? ` (${formattedDate})` : ''}\n${anno.content || ''}`
             : `${anno.author}: ${anno.content || ''}`;
 
+          const isDragging = draggingAnno === anno.id;
+          const currentOffset = isDragging ? dragOffset : { x: 0, y: 0 };
+
           return (
             <div
               key={anno.id}
-              onClick={(e) => {
-                e.stopPropagation();
-                onAnnotationClick?.(anno);
-              }}
-              className={`absolute cursor-pointer rounded-[2px] transition-[opacity,box-shadow] duration-150 hover:shadow-[0_2px_8px_rgba(16,24,40,0.18)] type-${anno.type}`}
+              onPointerDown={(e) => handlePointerDown(e, anno.id)}
+              onPointerMove={(e) => handlePointerMove(e, anno.id)}
+              onPointerUp={(e) => handlePointerUp(e, anno)}
+              className={`absolute cursor-pointer rounded-[2px] transition-[opacity,box-shadow] duration-150 hover:shadow-[0_2px_8px_rgba(16,24,40,0.18)] type-${anno.type} ${isDragging ? 'shadow-lg z-50' : ''}`}
               style={{
-                left: `${scaledBbox.x}px`,
-                top: `${scaledBbox.y}px`,
+                left: `${scaledBbox.x + currentOffset.x * zoom}px`,
+                top: `${scaledBbox.y + currentOffset.y * zoom}px`,
                 width: `${scaledBbox.width}px`,
                 height: `${scaledBbox.height}px`,
                 backgroundColor: anno.type === 'highlight' ? (anno.color || '#ffeb3b') : undefined,
diff --git a/frontend/src/viewer/PDFViewer.tsx b/frontend/src/viewer/PDFViewer.tsx
index a8f94da..b8c0cf8 100644
--- a/frontend/src/viewer/PDFViewer.tsx
+++ b/frontend/src/viewer/PDFViewer.tsx
@@ -28,6 +28,8 @@ interface PDFViewerProps {
   searchResults?: SearchResult[];
   searchCurrentMatch?: number;
   onAnnotationAdded?: (anno: Annotation) => void;
+  onAnnotationUpdate?: (anno: Annotation) => void;
+  onAnnotationClick?: (anno: Annotation) => void;
   onPageVisible?: (pageIndex: number) => void;
   onRedactArea?: (pageIndex: number, bounds: Rect) => void;
   onPlaceText?: (pageIndex: number, rectPts: Rect, text: string) => void;
@@ -65,6 +67,8 @@ export const PDFViewer = React.forwardRef<PDFViewerRef, PDFViewerProps>(({
   searchResults,
   searchCurrentMatch,
   onAnnotationAdded,
+  onAnnotationUpdate,
+  onAnnotationClick,
   onPageVisible,
   onRedactArea,
   onPlaceText,
@@ -79,7 +83,6 @@ export const PDFViewer = React.forwardRef<PDFViewerRef, PDFViewerProps>(({
   const [containerHeight, setContainerHeight] = useState(800);
   const [pageTexts, setPageTexts] = useState<Record<number, Glyph[]>>({});
   const verifiedPagesRef = useRef<Set<number>>(new Set());
-
   // Reset cached page renders when switching documents
   useEffect(() => {
     setRenderedPages([]);
@@ -387,6 +390,8 @@ export const PDFViewer = React.forwardRef<PDFViewerRef, PDFViewerProps>(({
                     height={page.height}
                     zoom={zoom}
                     annotations={annotations}
+                    onAnnotationClick={onAnnotationClick}
+                    onAnnotationUpdate={onAnnotationUpdate}
                     onFieldChange={onFieldChange}
                   />