diff --git a/packages/review-editor/components/AllFilesDiffView.tsx b/packages/review-editor/components/AllFilesDiffView.tsx
index aabac289..3effd001 100644
--- a/packages/review-editor/components/AllFilesDiffView.tsx
+++ b/packages/review-editor/components/AllFilesDiffView.tsx
@@ -101,6 +101,7 @@ export const AllFilesDiffView: React.FC<AllFilesDiffViewProps> = ({
     setActiveFilePath(null);
     setCollapsedFiles(new Set());
     collapseHistory.current = [];
+    setFileCommentAnchor(null);
   }, [files]);
 
   const scrollRef = useRef<HTMLDivElement>(null);
@@ -515,9 +516,11 @@ export const AllFilesDiffView: React.FC<AllFilesDiffViewProps> = ({
 
       {fileCommentAnchor && onAddFileComment && (
         <CommentPopover
+          key={`file:${prUrl ?? ''}:${prDiffScope ?? ''}:${fileCommentAnchor.filePath}`}
           anchorEl={fileCommentAnchor.el}
           contextText={fileCommentAnchor.filePath.split('/').pop() || fileCommentAnchor.filePath}
           isGlobal={false}
+          draftKey={`file:${prUrl ?? ''}:${prDiffScope ?? ''}:${fileCommentAnchor.filePath}`}
           onSubmit={(text) => {
             onAddFileComment(fileCommentAnchor.filePath, text);
             setFileCommentAnchor(null);
diff --git a/packages/review-editor/components/DiffViewer.tsx b/packages/review-editor/components/DiffViewer.tsx
index 912737c1..fd99a2b4 100644
--- a/packages/review-editor/components/DiffViewer.tsx
+++ b/packages/review-editor/components/DiffViewer.tsx
@@ -120,6 +120,9 @@ interface DiffViewerProps {
   oldPath?: string;
   /** Base branch override used for file-content lookups (branch / merge-base modes only). */
   reviewBase?: string;
+  /** Current PR url + diff scope — used to namespace file-comment drafts so they don't leak across in-place PR switches. */
+  prUrl?: string;
+  prDiffScope?: string;
   isFocused?: boolean;
   diffStyle: 'split' | 'unified';
   diffOverflow?: 'scroll' | 'wrap';
@@ -165,6 +168,8 @@ export const DiffViewer: React.FC<DiffViewerProps> = ({
   filePath,
   oldPath,
   reviewBase,
+  prUrl,
+  prDiffScope,
   isFocused = false,
   diffStyle,
   diffOverflow,
@@ -621,6 +626,7 @@ export const DiffViewer: React.FC<DiffViewerProps> = ({
           anchorEl={fileCommentAnchor}
           contextText={filePath.split('/').pop() || filePath}
           isGlobal={false}
+          draftKey={`file:${prUrl ?? ''}:${prDiffScope ?? ''}:${filePath}`}
           onSubmit={(text) => {
             onAddFileComment(text);
             setFileCommentAnchor(null);
diff --git a/packages/review-editor/dock/panels/ReviewDiffPanel.tsx b/packages/review-editor/dock/panels/ReviewDiffPanel.tsx
index 7de62e3e..5e08df4f 100644
--- a/packages/review-editor/dock/panels/ReviewDiffPanel.tsx
+++ b/packages/review-editor/dock/panels/ReviewDiffPanel.tsx
@@ -71,6 +71,8 @@ export const ReviewDiffPanel: React.FC<IDockviewPanelProps> = (props) => {
         filePath={file.path}
         oldPath={file.oldPath}
         reviewBase={state.reviewBase}
+        prUrl={state.prMetadata?.url}
+        prDiffScope={state.prDiffScope}
         isFocused={isFocusedFile}
         diffStyle={state.diffStyle}
         diffOverflow={state.diffOverflow}
diff --git a/packages/ui/components/CommentPopover.tsx b/packages/ui/components/CommentPopover.tsx
index 4baa1175..d56e50f6 100644
--- a/packages/ui/components/CommentPopover.tsx
+++ b/packages/ui/components/CommentPopover.tsx
@@ -20,11 +20,28 @@ interface CommentPopoverProps {
   onSubmit: (text: string, images?: ImageAttachment[]) => void;
   /** Called when popover is closed/cancelled */
   onClose: () => void;
+  /** Opt-in: persist text + images across close/reopen, keyed by this string. Cleared on submit. */
+  draftKey?: string;
 }
 
 const MAX_POPOVER_WIDTH = 384;
 const GAP = 8;
 
+// Module-level draft store: survives popover unmount so reopening the same key restores in-progress text.
+const draftStore = new Map<string, { text: string; images: ImageAttachment[] }>();
+
+/** Mirrors the latest text + images into `draftStore[draftKey]` so they outlive popover unmount. No-op without a key. */
+function useCommentDraftSync(draftKey: string | undefined, text: string, images: ImageAttachment[]) {
+  useEffect(() => {
+    if (!draftKey) return;
+    if (text.trim() || images.length > 0) {
+      draftStore.set(draftKey, { text, images });
+    } else {
+      draftStore.delete(draftKey);
+    }
+  }, [draftKey, text, images]);
+}
+
 function computePosition(anchorRect: DOMRect): { top: number; left: number; flipAbove: boolean; width: number } {
   const spaceBelow = window.innerHeight - anchorRect.bottom;
   const flipAbove = spaceBelow < 280;
@@ -48,15 +65,19 @@ export const CommentPopover: React.FC<CommentPopoverProps> = ({
   initialText = '',
   onSubmit,
   onClose,
+  draftKey,
 }) => {
   const [mode, setMode] = useState<'popover' | 'dialog'>('popover');
-  const [text, setText] = useState(initialText);
-  const [images, setImages] = useState<ImageAttachment[]>([]);
+  const initialDraft = draftKey ? draftStore.get(draftKey) : undefined;
+  const [text, setText] = useState(initialDraft?.text ?? initialText);
+  const [images, setImages] = useState<ImageAttachment[]>(initialDraft?.images ?? []);
   const [position, setPosition] = useState<{ top: number; left: number; flipAbove: boolean; width: number } | null>(null);
   const textareaRef = useRef<HTMLTextAreaElement>(null);
   const popoverRef = useRef<HTMLDivElement>(null);
   const { dragPosition, dragHandleProps, wasDragged, reset: resetDrag } = useDraggable(popoverRef);
 
+  useCommentDraftSync(draftKey, text, images);
+
   // Reset drag when anchor changes (new annotation) or mode switches
   useEffect(() => { resetDrag(); }, [anchorEl, anchorRect, resetDrag]);
   useEffect(() => { if (mode === 'popover') resetDrag(); }, [mode, resetDrag]);
@@ -111,9 +132,10 @@ export const CommentPopover: React.FC<CommentPopoverProps> = ({
 
   const handleSubmit = useCallback(() => {
     if (text.trim() || images.length > 0) {
+      if (draftKey) draftStore.delete(draftKey);
       onSubmit(text, images.length > 0 ? images : undefined);
     }
-  }, [text, images, onSubmit]);
+  }, [text, images, onSubmit, draftKey]);
 
   const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
     if (e.key === 'Escape') {