diff --git a/packages/ui/src/components/views/FilesView.tsx b/packages/ui/src/components/views/FilesView.tsx
index 01d06de8..a829a780 100644
--- a/packages/ui/src/components/views/FilesView.tsx
+++ b/packages/ui/src/components/views/FilesView.tsx
@@ -224,6 +224,47 @@ const FileStatusDot: React.FC<{ status: FileStatus }> = ({ status }) => {
   return <span className="size-2 rounded-full" style={{ backgroundColor: color }} />;
 };
 
+const ScrollingFileName: React.FC<{ name: string }> = ({ name }) => {
+  const containerRef = React.useRef<HTMLSpanElement | null>(null);
+  const textRef = React.useRef<HTMLSpanElement | null>(null);
+  const [overflowing, setOverflowing] = React.useState(false);
+
+  React.useLayoutEffect(() => {
+    const container = containerRef.current;
+    const text = textRef.current;
+    if (!container || !text) {
+      return;
+    }
+
+    const updateOverflow = () => {
+      setOverflowing(text.scrollWidth > container.clientWidth + 1);
+    };
+
+    updateOverflow();
+    const resizeObserver = new ResizeObserver(updateOverflow);
+    resizeObserver.observe(container);
+    resizeObserver.observe(text);
+
+    return () => {
+      resizeObserver.disconnect();
+    };
+  }, [name]);
+
+  return (
+    <span ref={containerRef} className="relative block min-w-0 flex-1 overflow-hidden whitespace-nowrap">
+      <span ref={textRef} aria-hidden="true" className="invisible absolute whitespace-nowrap">{name}</span>
+      {overflowing ? (
+        <span className="open-file-name-marquee-track">
+          <span className="open-file-name-marquee-item">{name}</span>
+          <span className="open-file-name-marquee-item" aria-hidden="true">{name}</span>
+        </span>
+      ) : (
+        <span className="block min-w-0 truncate">{name}</span>
+      )}
+    </span>
+  );
+};
+
 const shouldIgnoreEntryName = (name: string): boolean => DEFAULT_IGNORED_DIR_NAMES.has(name);
 
 const shouldIgnorePath = (path: string): boolean => {
@@ -237,6 +278,15 @@ const isDirectoryReadError = (error: unknown): boolean => {
   return normalized.includes('is a directory') || normalized.includes('eisdir');
 };
 
+const isFileMissingError = (error: unknown): boolean => {
+  const message = error instanceof Error ? error.message : String(error ?? '');
+  const normalized = message.toLowerCase();
+  return normalized.includes('file not found')
+    || normalized.includes('enoent')
+    || normalized.includes('no such file')
+    || normalized.includes('does not exist');
+};
+
 const MAX_VIEW_CHARS = 200_000;
 const FILE_EDITOR_AUTO_SAVE_KEY = 'openchamber:files:auto-save-enabled';
 
@@ -1347,6 +1397,32 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     return null;
   }, [files]);
 
+  React.useEffect(() => {
+    if (!root || !files.statFile || openPaths.length === 0) {
+      return;
+    }
+
+    let cancelled = false;
+    const paths = [...openPaths];
+
+    void Promise.all(paths.map(async (path) => {
+      try {
+        const stat = await files.statFile?.(path);
+        if (!cancelled && stat && !stat.isFile) {
+          removeOpenPathsByPrefix(root, path);
+        }
+      } catch (error) {
+        if (!cancelled && isFileMissingError(error)) {
+          removeOpenPathsByPrefix(root, path);
+        }
+      }
+    }));
+
+    return () => {
+      cancelled = true;
+    };
+  }, [files, openPaths, removeOpenPathsByPrefix, root]);
+
   const displayedContent = React.useMemo(() =>
     fileContent.length > MAX_VIEW_CHARS
       ? `${fileContent.slice(0, MAX_VIEW_CHARS)}\n\n… truncated …`
@@ -1592,6 +1668,19 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
           }
           return;
         }
+        if (isFileMissingError(error)) {
+          if (root) {
+            removeOpenPathsByPrefix(root, node.path);
+          }
+          setFileContent('');
+          setDraftContent('');
+          setFileError(null);
+          lastLoadedFileStatRef.current = null;
+          if (isMobile) {
+            setShowMobilePageContent(false);
+          }
+          return;
+        }
         setFileContent('');
         setDraftContent('');
         setFileError(error instanceof Error ? error.message : t('filesView.error.readFileFailed'));
@@ -1602,7 +1691,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
           setFileLoading(false);
         }
       });
-  }, [expandPaths, isMobile, loadDirectory, mode, readFile, readFileStat, root, runtime.isDesktop, searchQuery, setSelectedPath, t]);
+  }, [expandPaths, isMobile, loadDirectory, mode, readFile, readFileStat, removeOpenPathsByPrefix, root, runtime.isDesktop, searchQuery, setSelectedPath, t]);
 
   const ensurePathVisible = React.useCallback(async (targetPath: string, includeTarget: boolean) => {
     if (!root) {
@@ -2889,11 +2978,11 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
                     aria-label={t('filesView.editor.openFilesAria')}
                   >
                     <FileTypeIcon filePath={selectedFile.path} extension={selectedFile.extension} className="size-3.5 flex-shrink-0" />
-                    <span className="min-w-0 flex-1 truncate">{selectedFile.name}</span>
+                    <ScrollingFileName name={selectedFile.name} />
                     <Icon name="arrow-down-s" className="size-4 flex-shrink-0 text-muted-foreground" />
                   </button>
                 </DropdownMenuTrigger>
-                <DropdownMenuContent align="start" className="min-w-[16rem]">
+                <DropdownMenuContent align="start" className="w-[min(24rem,calc(100vw-2rem))] max-w-[calc(100vw-2rem)]">
                   {openFiles.map((file) => {
                     const isActive = selectedFile?.path === file.path;
                     return (
@@ -2910,13 +2999,13 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
                           }
                         }}
                         className={cn(
-                          'flex items-center justify-between gap-2',
+                          'flex min-w-0 items-center justify-between gap-2 overflow-hidden',
                           isActive && 'bg-[var(--interactive-selection)] text-[var(--interactive-selection-foreground)]'
                         )}
                       >
-                        <span className="flex min-w-0 flex-1 items-center gap-2 truncate">
+                        <span className="flex min-w-0 flex-1 items-center gap-2 overflow-hidden">
                           <FileTypeIcon filePath={file.path} extension={file.extension} className="size-3.5 flex-shrink-0" />
-                          <span className="min-w-0 flex-1 truncate">{file.name}</span>
+                          <ScrollingFileName name={file.name} />
                         </span>
                         <button
                           type="button"
@@ -2930,7 +3019,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
                             event.stopPropagation();
                             handleCloseFile(file.path);
                           }}
-                          className="inline-flex size-6 items-center justify-center rounded-md text-[var(--surface-muted-foreground)] hover:text-[var(--surface-foreground)]"
+                          className="inline-flex size-6 shrink-0 items-center justify-center rounded-md text-[var(--surface-muted-foreground)] hover:text-[var(--surface-foreground)]"
                           aria-label={t('filesView.editor.closeFileAria', { name: file.name })}
                         >
                           <Icon name="close" className="size-3.5" />
diff --git a/packages/ui/src/contexts/RuntimeAPIProvider.tsx b/packages/ui/src/contexts/RuntimeAPIProvider.tsx
index a982498f..c78f8ecf 100644
--- a/packages/ui/src/contexts/RuntimeAPIProvider.tsx
+++ b/packages/ui/src/contexts/RuntimeAPIProvider.tsx
@@ -13,6 +13,20 @@ import {
 function withContentCache(files: FilesAPI): FilesAPI {
   const cache = new Map<string, { content: string; path: string; size?: number; mtimeMs?: number }>();
 
+  const removeCacheEntry = (path: string) => {
+    cache.delete(path);
+    removeContentBytes(path);
+  };
+
+  const removeCacheEntriesByPrefix = (path: string) => {
+    const prefix = path.endsWith('/') ? path : `${path}/`;
+    for (const key of cache.keys()) {
+      if (key === path || key.startsWith(prefix)) {
+        removeCacheEntry(key);
+      }
+    }
+  };
+
   /** Whether cached metadata still matches the file on disk. */
   const statMatches = (
     cached: { size?: number; mtimeMs?: number },
@@ -86,10 +100,12 @@ function withContentCache(files: FilesAPI): FilesAPI {
         if (hit) {
           // Validate cached entry is still fresh
           if (files.statFile) {
-            const latest = await files.statFile(path).catch(() => null);
-            if (latest && !statMatches(hit, latest)) {
-              cache.delete(path);
-              removeContentBytes(path);
+            const latest = await files.statFile(path).catch(() => {
+              removeCacheEntry(path);
+              return null;
+            });
+            if (!latest || !statMatches(hit, latest)) {
+              removeCacheEntry(path);
               return readFreshFile(path);
             }
           }
@@ -104,26 +120,22 @@ function withContentCache(files: FilesAPI): FilesAPI {
   // Invalidate cache on writes, deletes, renames
   const cachedWriteFile: FilesAPI['writeFile'] = files.writeFile
     ? async (path, content) => {
-        cache.delete(path);
-        removeContentBytes(path);
+        removeCacheEntry(path);
         return files.writeFile!(path, content);
       }
     : undefined;
 
   const cachedDelete: FilesAPI['delete'] = files.delete
     ? async (path) => {
-        cache.delete(path);
-        removeContentBytes(path);
+        removeCacheEntriesByPrefix(path);
         return files.delete!(path);
       }
     : undefined;
 
   const cachedRename: FilesAPI['rename'] = files.rename
     ? async (oldPath, newPath) => {
-        cache.delete(oldPath);
-        removeContentBytes(oldPath);
-        cache.delete(newPath);
-        removeContentBytes(newPath);
+        removeCacheEntriesByPrefix(oldPath);
+        removeCacheEntriesByPrefix(newPath);
         return files.rename!(oldPath, newPath);
       }
     : undefined;
diff --git a/packages/ui/src/index.css b/packages/ui/src/index.css
index 04caf202..516937ea 100644
--- a/packages/ui/src/index.css
+++ b/packages/ui/src/index.css
@@ -1442,6 +1442,23 @@ input[aria-label="Terminal input"] {
   100% { transform: translateX(-100%); }
 }
 
+@keyframes open-file-name-marquee-scroll {
+  0% { transform: translateX(0); }
+  100% { transform: translateX(-50%); }
+}
+
+.open-file-name-marquee-track {
+  display: inline-flex;
+  min-width: max-content;
+  animation: open-file-name-marquee-scroll var(--open-file-name-marquee-duration, 14s) linear infinite;
+  will-change: transform;
+}
+
+.open-file-name-marquee-item {
+  flex-shrink: 0;
+  padding-right: 2rem;
+}
+
 .marquee-text {
   display: inline-block;
   white-space: nowrap;
@@ -1459,11 +1476,30 @@ input[aria-label="Terminal input"] {
 
 @media (prefers-reduced-motion: reduce) {
   .marquee-text--auto,
+  .open-file-name-marquee-track,
   .group:hover .marquee-text--active,
   .marquee-text--active:hover {
     animation: none;
   }
 
+  .open-file-name-marquee-track {
+    display: block;
+    min-width: 0;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    will-change: auto;
+  }
+
+  .open-file-name-marquee-track .open-file-name-marquee-item {
+    display: inline;
+    padding-right: 0;
+  }
+
+  .open-file-name-marquee-track .open-file-name-marquee-item[aria-hidden="true"] {
+    display: none;
+  }
+
   .animate-busy-pulse {
     animation: none;
   }