diff --git a/frontend/.eslintrc.js b/frontend/.eslintrc.js
new file mode 100644
index 000000000..6146714b4
--- /dev/null
+++ b/frontend/.eslintrc.js
@@ -0,0 +1,54 @@
+module.exports = {
+  extends: [
+    'react-app',
+    'react-app/jest'
+  ],
+  rules: {
+    // Custom rules to prevent dangerous file.name as ID patterns
+    'no-file-name-as-id': 'error'
+  },
+  overrides: [
+    {
+      files: ['**/*.ts', '**/*.tsx'],
+      rules: {
+        // Prevent file.name being used where FileId is expected
+        'no-restricted-syntax': [
+          'error',
+          {
+            selector: 'MemberExpression[object.name="file"][property.name="name"]',
+            message: 'Avoid using file.name directly. Use FileWithId.fileId or safeGetFileId() instead to prevent ID collisions.'
+          },
+          {
+            selector: 'CallExpression[callee.name="createOperation"] > ArrayExpression > CallExpression[callee.property.name="map"] > ArrowFunctionExpression > MemberExpression[object.name="f"][property.name="name"]',
+            message: 'Dangerous pattern: Using file.name as ID in createOperation. Use FileWithId.fileId instead.'
+          },
+          {
+            selector: 'ArrayExpression[elements.length>0] CallExpression[callee.property.name="map"] > ArrowFunctionExpression > MemberExpression[property.name="name"]',
+            message: 'Potential file.name as ID usage detected. Ensure proper FileId usage instead of file.name.'
+          }
+        ]
+      }
+    }
+  ],
+  settings: {
+    // Custom settings for our file ID validation
+    'file-id-validation': {
+      // Functions that should only accept FileId, not strings
+      'file-id-only-functions': [
+        'recordOperation',
+        'markOperationApplied', 
+        'markOperationFailed',
+        'removeFiles',
+        'updateFileRecord',
+        'pinFile',
+        'unpinFile'
+      ],
+      // Functions that should accept FileWithId instead of File
+      'file-with-id-functions': [
+        'createOperation',
+        'executeOperation',
+        'isFilePinned'
+      ]
+    }
+  }
+};
\ No newline at end of file
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 8a30d3869..97503ba21 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -14,6 +14,9 @@ import "./styles/cookieconsent.css";
 import "./index.css";
 import { RightRailProvider } from "./contexts/RightRailContext";
 
+// Import file ID safety validators (development only)
+import "./utils/fileIdSafety";
+
 // Loading component for i18next suspense
 const LoadingFallback = () => (
   <div
diff --git a/frontend/src/components/fileEditor/FileEditor.tsx b/frontend/src/components/fileEditor/FileEditor.tsx
index bf95d9796..7acfdead8 100644
--- a/frontend/src/components/fileEditor/FileEditor.tsx
+++ b/frontend/src/components/fileEditor/FileEditor.tsx
@@ -16,12 +16,12 @@ import styles from './FileEditor.module.css';
 import FileEditorThumbnail from './FileEditorThumbnail';
 import FilePickerModal from '../shared/FilePickerModal';
 import SkeletonLoader from '../shared/SkeletonLoader';
-import { FileId } from '../../types/file';
+import { FileId, FileWithId } from '../../types/fileContext';
 
 
 interface FileEditorProps {
-  onOpenPageEditor?: (file: File) => void;
-  onMergeFiles?: (files: File[]) => void;
+  onOpenPageEditor?: (file: FileWithId) => void;
+  onMergeFiles?: (files: FileWithId[]) => void;
   toolMode?: boolean;
   showUpload?: boolean;
   showBulkActions?: boolean;
@@ -421,7 +421,7 @@ const FileEditor = ({
     if (startIndex === -1) return;
 
     const recordsToMerge = activeFileRecords.slice(startIndex);
-    const filesToMerge = recordsToMerge.map(r => selectors.getFile(r.id)).filter(Boolean) as File[];
+    const filesToMerge = recordsToMerge.map(r => selectors.getFile(r.id)).filter(Boolean) as FileWithId[];
     if (onMergeFiles) {
       onMergeFiles(filesToMerge);
     }
diff --git a/frontend/src/components/fileEditor/FileEditorThumbnail.tsx b/frontend/src/components/fileEditor/FileEditorThumbnail.tsx
index e82483898..bfeb404c5 100644
--- a/frontend/src/components/fileEditor/FileEditorThumbnail.tsx
+++ b/frontend/src/components/fileEditor/FileEditorThumbnail.tsx
@@ -61,8 +61,8 @@ const FileEditorThumbnail = ({
 
   // Resolve the actual File object for pin/unpin operations
   const actualFile = useMemo(() => {
-    return activeFiles.find((f: File) => f.name === file.name && f.size === file.size);
-  }, [activeFiles, file.name, file.size]);
+    return activeFiles.find(f => f.fileId === file.id);
+  }, [activeFiles, file.id]);
   const isPinned = actualFile ? isFilePinned(actualFile) : false;
 
   const downloadSelectedFile = useCallback(() => {
diff --git a/frontend/src/components/pageEditor/FileThumbnail.tsx b/frontend/src/components/pageEditor/FileThumbnail.tsx
index 1eda1f6c8..ad81ce463 100644
--- a/frontend/src/components/pageEditor/FileThumbnail.tsx
+++ b/frontend/src/components/pageEditor/FileThumbnail.tsx
@@ -61,8 +61,8 @@ const FileThumbnail = ({
 
   // Resolve the actual File object for pin/unpin operations
   const actualFile = useMemo(() => {
-    return activeFiles.find((f: File) => f.name === file.name && f.size === file.size);
-  }, [activeFiles, file.name, file.size]);
+    return activeFiles.find(f => f.fileId === file.id);
+  }, [activeFiles, file.id]);
   const isPinned = actualFile ? isFilePinned(actualFile) : false;
 
   const downloadSelectedFile = useCallback(() => {
diff --git a/frontend/src/components/shared/FileCard.tsx b/frontend/src/components/shared/FileCard.tsx
index 73ae01dba..b433be2ca 100644
--- a/frontend/src/components/shared/FileCard.tsx
+++ b/frontend/src/components/shared/FileCard.tsx
@@ -25,7 +25,7 @@ interface FileCardProps {
 const FileCard = ({ file, record, onRemove, onDoubleClick, onView, onEdit, isSelected, onSelect, isSupported = true }: FileCardProps) => {
   const { t } = useTranslation();
   // Use record thumbnail if available, otherwise fall back to IndexedDB lookup
-  const fileMetadata = record ? { id: record.id, name: file.name, type: file.type, size: file.size, lastModified: file.lastModified } : null;
+  const fileMetadata = record ? { id: record.id, name: record.name, type: record.type, size: record.size, lastModified: record.lastModified } : null;
   const { thumbnail: indexedDBThumb, isGenerating } = useIndexedDBThumbnail(fileMetadata);
   const thumb = record?.thumbnailUrl || indexedDBThumb;
   const [isHovered, setIsHovered] = useState(false);
diff --git a/frontend/src/components/shared/FileGrid.tsx b/frontend/src/components/shared/FileGrid.tsx
index 1a43196d6..2da1e2b09 100644
--- a/frontend/src/components/shared/FileGrid.tsx
+++ b/frontend/src/components/shared/FileGrid.tsx
@@ -124,8 +124,12 @@ const FileGrid = ({
         style={{ overflowY: "auto", width: "100%" }}
       >
         {displayFiles.map((item, idx) => {
-          const fileId = item.record?.id || item.file.name as FileId /* FIX ME: This doesn't seem right */;
-          const originalIdx = files.findIndex(f => (f.record?.id || f.file.name) === fileId);
+          if (!item.record?.id) {
+            console.error('FileGrid: File missing FileRecord with proper ID:', item.file.name);
+            return null;
+          }
+          const fileId = item.record.id;
+          const originalIdx = files.findIndex(f => f.record?.id === fileId);
           const supported = isFileSupported ? isFileSupported(item.file.name) : true;
           return (
             <FileCard
diff --git a/frontend/src/components/tools/convert/ConvertSettings.tsx b/frontend/src/components/tools/convert/ConvertSettings.tsx
index bae2954a9..86f22f973 100644
--- a/frontend/src/components/tools/convert/ConvertSettings.tsx
+++ b/frontend/src/components/tools/convert/ConvertSettings.tsx
@@ -22,13 +22,13 @@ import {
   OUTPUT_OPTIONS,
   FIT_OPTIONS
 } from "../../../constants/convertConstants";
-import { FileId } from "../../../types/file";
+import { FileWithId } from "../../../types/fileContext";
 
 interface ConvertSettingsProps {
   parameters: ConvertParameters;
   onParameterChange: (key: keyof ConvertParameters, value: any) => void;
   getAvailableToExtensions: (fromExtension: string) => Array<{value: string, label: string, group: string}>;
-  selectedFiles: File[];
+  selectedFiles: FileWithId[];
   disabled?: boolean;
 }
 
@@ -129,7 +129,7 @@ const ConvertSettings = ({
   };
 
   const filterFilesByExtension = (extension: string) => {
-    const files = activeFiles.map(fileId => selectors.getFile(fileId)).filter(Boolean) as File[];
+    const files = activeFiles.map(fileId => selectors.getFile(fileId)).filter(Boolean) as FileWithId[];
     return files.filter(file => {
       const fileExtension = detectFileExtension(file.name);
 
@@ -143,21 +143,8 @@ const ConvertSettings = ({
     });
   };
 
-  const updateFileSelection = (files: File[]) => {
-    // Map File objects to their actual IDs in FileContext
-    const fileIds = files.map(file => {
-      // Find the file ID by matching file properties
-      const fileRecord = state.files.ids
-        .map(id => selectors.getFileRecord(id))
-        .find(record =>
-          record &&
-          record.name === file.name &&
-          record.size === file.size &&
-          record.lastModified === file.lastModified
-        );
-      return fileRecord?.id;
-    }).filter((id): id is FileId => id !== undefined); // Type guard to ensure only strings
-
+  const updateFileSelection = (files: FileWithId[]) => {
+    const fileIds = files.map(file => file.fileId);
     setSelectedFiles(fileIds);
   };
 
diff --git a/frontend/src/components/tools/convert/ConvertToPdfaSettings.tsx b/frontend/src/components/tools/convert/ConvertToPdfaSettings.tsx
index e1a662bd2..ccad7ce67 100644
--- a/frontend/src/components/tools/convert/ConvertToPdfaSettings.tsx
+++ b/frontend/src/components/tools/convert/ConvertToPdfaSettings.tsx
@@ -3,11 +3,12 @@ import { Stack, Text, Select, Alert } from '@mantine/core';
 import { useTranslation } from 'react-i18next';
 import { ConvertParameters } from '../../../hooks/tools/convert/useConvertParameters';
 import { usePdfSignatureDetection } from '../../../hooks/usePdfSignatureDetection';
+import { FileWithId } from '../../../types/fileContext';
 
 interface ConvertToPdfaSettingsProps {
   parameters: ConvertParameters;
   onParameterChange: (key: keyof ConvertParameters, value: any) => void;
-  selectedFiles: File[];
+  selectedFiles: FileWithId[];
   disabled?: boolean;
 }
 
diff --git a/frontend/src/components/tools/shared/FileStatusIndicator.tsx b/frontend/src/components/tools/shared/FileStatusIndicator.tsx
index 9b375fc2f..214159b05 100644
--- a/frontend/src/components/tools/shared/FileStatusIndicator.tsx
+++ b/frontend/src/components/tools/shared/FileStatusIndicator.tsx
@@ -6,9 +6,10 @@ import UploadIcon from '@mui/icons-material/Upload';
 import { useFilesModalContext } from "../../../contexts/FilesModalContext";
 import { useAllFiles } from "../../../contexts/FileContext";
 import { useFileManager } from "../../../hooks/useFileManager";
+import { FileWithId } from "../../../types/fileContext";
 
 export interface FileStatusIndicatorProps {
-  selectedFiles?: File[];
+  selectedFiles?: FileWithId[];
   placeholder?: string;
 }
 
diff --git a/frontend/src/components/tools/shared/FilesToolStep.tsx b/frontend/src/components/tools/shared/FilesToolStep.tsx
index b062e9c02..11f7d4e02 100644
--- a/frontend/src/components/tools/shared/FilesToolStep.tsx
+++ b/frontend/src/components/tools/shared/FilesToolStep.tsx
@@ -1,9 +1,10 @@
 import React from 'react';
 import { useTranslation } from 'react-i18next';
 import FileStatusIndicator from './FileStatusIndicator';
+import { FileWithId } from '../../../types/fileContext';
 
 export interface FilesToolStepProps {
-  selectedFiles: File[];
+  selectedFiles: FileWithId[];
   isCollapsed?: boolean;
   onCollapsedClick?: () => void;
   placeholder?: string;
diff --git a/frontend/src/components/tools/shared/createToolFlow.tsx b/frontend/src/components/tools/shared/createToolFlow.tsx
index b6a7594c6..1bee8b9fc 100644
--- a/frontend/src/components/tools/shared/createToolFlow.tsx
+++ b/frontend/src/components/tools/shared/createToolFlow.tsx
@@ -4,9 +4,10 @@ import { createToolSteps, ToolStepProvider } from './ToolStep';
 import OperationButton from './OperationButton';
 import { ToolOperationHook } from '../../../hooks/tools/shared/useToolOperation';
 import { ToolWorkflowTitle, ToolWorkflowTitleProps } from './ToolWorkflowTitle';
+import { FileWithId } from '../../../types/fileContext';
 
 export interface FilesStepConfig {
-  selectedFiles: File[];
+  selectedFiles: FileWithId[];
   isCollapsed?: boolean;
   placeholder?: string;
   onCollapsedClick?: () => void;
diff --git a/frontend/src/components/viewer/Viewer.tsx b/frontend/src/components/viewer/Viewer.tsx
index 0932e995b..53d9e98e2 100644
--- a/frontend/src/components/viewer/Viewer.tsx
+++ b/frontend/src/components/viewer/Viewer.tsx
@@ -15,6 +15,7 @@ import { fileStorage } from "../../services/fileStorage";
 import SkeletonLoader from '../shared/SkeletonLoader';
 import { useFileState, useFileActions, useCurrentFile } from "../../contexts/FileContext";
 import { useFileWithUrl } from "../../hooks/useFileWithUrl";
+import { isFileObject } from "../../types/fileContext";
 import { FileId } from "../../types/file";
 
 
@@ -201,7 +202,7 @@ const Viewer = ({
   const effectiveFile = React.useMemo(() => {
     if (previewFile) {
       // Validate the preview file
-      if (!(previewFile instanceof File)) {
+      if (!isFileObject(previewFile)) {
         return null;
       }
 
diff --git a/frontend/src/contexts/FileContext.tsx b/frontend/src/contexts/FileContext.tsx
index 39faa0643..97ac3c645 100644
--- a/frontend/src/contexts/FileContext.tsx
+++ b/frontend/src/contexts/FileContext.tsx
@@ -19,7 +19,10 @@ import {
   FileContextStateValue,
   FileContextActionsValue,
   FileContextActions,
-  FileRecord
+  FileId,
+  FileRecord,
+  FileWithId,
+  createFileWithId
 } from '../types/fileContext';
 
 // Import modular components
@@ -29,7 +32,6 @@ import { AddedFile, addFiles, consumeFiles, undoConsumeFiles, createFileActions
 import { FileLifecycleManager } from './file/lifecycle';
 import { FileStateContext, FileActionsContext } from './file/contexts';
 import { IndexedDBProvider, useIndexedDB } from './IndexedDBContext';
-import { FileId } from '../types/file';
 
 const DEBUG = process.env.NODE_ENV === 'development';
 
@@ -79,7 +81,7 @@ function FileContextInner({
   }
 
   // File operations using unified addFiles helper with persistence
-  const addRawFiles = useCallback(async (files: File[], options?: { insertAfterPageId?: string; selectFiles?: boolean }): Promise<File[]> => {
+  const addRawFiles = useCallback(async (files: File[], options?: { insertAfterPageId?: string; selectFiles?: boolean }): Promise<FileWithId[]> => {
     const addedFilesWithIds = await addFiles('raw', { files, ...options }, stateRef, filesRef, dispatch, lifecycleManager);
 
     // Auto-select the newly added files if requested
@@ -98,15 +100,15 @@ function FileContextInner({
       }));
     }
 
-    return addedFilesWithIds.map(({ file }) => file);
+    return addedFilesWithIds.map(({ file, id }) => createFileWithId(file, id));
   }, [indexedDB, enablePersistence]);
 
-  const addProcessedFiles = useCallback(async (filesWithThumbnails: Array<{ file: File; thumbnail?: string; pageCount?: number }>): Promise<File[]> => {
+  const addProcessedFiles = useCallback(async (filesWithThumbnails: Array<{ file: File; thumbnail?: string; pageCount?: number }>): Promise<FileWithId[]> => {
     const result = await addFiles('processed', { filesWithThumbnails }, stateRef, filesRef, dispatch, lifecycleManager);
-    return result.map(({ file }) => file);
+    return result.map(({ file, id }) => createFileWithId(file, id));
   }, []);
 
-  const addStoredFiles = useCallback(async (filesWithMetadata: Array<{ file: File; originalId: FileId; metadata: any }>, options?: { selectFiles?: boolean }): Promise<File[]> => {
+  const addStoredFiles = useCallback(async (filesWithMetadata: Array<{ file: File; originalId: FileId; metadata: any }>, options?: { selectFiles?: boolean }): Promise<FileWithId[]> => {
     const result = await addFiles('stored', { filesWithMetadata }, stateRef, filesRef, dispatch, lifecycleManager);
 
     // Auto-select the newly added files if requested
@@ -114,7 +116,7 @@ function FileContextInner({
       selectFiles(result);
     }
 
-    return result.map(({ file }) => file);
+    return result.map(({ file, id }) => createFileWithId(file, id));
   }, []);
 
   // Action creators
@@ -140,24 +142,14 @@ function FileContextInner({
     });
   }, []);
 
-  // File-to-ID wrapper functions for pinning
-  const pinFileWrapper = useCallback((file: File) => {
-    const fileId = findFileId(file);
-    if (fileId) {
-      baseActions.pinFile(fileId);
-    } else {
-      console.warn('File not found for pinning:', file.name);
-    }
-  }, [baseActions, findFileId]);
+  // File pinning functions - use FileWithId directly
+  const pinFileWrapper = useCallback((file: FileWithId) => {
+    baseActions.pinFile(file.fileId);
+  }, [baseActions]);
 
-  const unpinFileWrapper = useCallback((file: File) => {
-    const fileId = findFileId(file);
-    if (fileId) {
-      baseActions.unpinFile(fileId);
-    } else {
-      console.warn('File not found for unpinning:', file.name);
-    }
-  }, [baseActions, findFileId]);
+  const unpinFileWrapper = useCallback((file: FileWithId) => {
+    baseActions.unpinFile(file.fileId);
+  }, [baseActions]);
 
   // Complete actions object
   const actions = useMemo<FileContextActions>(() => ({
diff --git a/frontend/src/contexts/file/fileHooks.ts b/frontend/src/contexts/file/fileHooks.ts
index e1b8e5cc4..609d38ab5 100644
--- a/frontend/src/contexts/file/fileHooks.ts
+++ b/frontend/src/contexts/file/fileHooks.ts
@@ -9,7 +9,7 @@ import {
   FileContextStateValue,
   FileContextActionsValue
 } from './contexts';
-import { FileRecord } from '../../types/fileContext';
+import { FileRecord, FileWithId } from '../../types/fileContext';
 import { FileId } from '../../types/file';
 
 /**
@@ -123,7 +123,7 @@ export function useFileRecord(fileId: FileId): { file?: File; record?: FileRecor
 /**
  * Hook for all files (use sparingly - causes re-renders on file list changes)
  */
-export function useAllFiles(): { files: File[]; records: FileRecord[]; fileIds: FileId[] } {
+export function useAllFiles(): { files: FileWithId[]; records: FileRecord[]; fileIds: FileId[] } {
   const { state, selectors } = useFileState();
 
   return useMemo(() => ({
@@ -136,7 +136,7 @@ export function useAllFiles(): { files: File[]; records: FileRecord[]; fileIds:
 /**
  * Hook for selected files (optimized for selection-based UI)
  */
-export function useSelectedFiles(): { files: File[]; records: FileRecord[]; fileIds: FileId[] } {
+export function useSelectedFiles(): { files: FileWithId[]; records: FileRecord[]; fileIds: FileId[] } {
   const { state, selectors } = useFileState();
 
   return useMemo(() => ({
diff --git a/frontend/src/contexts/file/fileSelectors.ts b/frontend/src/contexts/file/fileSelectors.ts
index 2111693cf..e5876813b 100644
--- a/frontend/src/contexts/file/fileSelectors.ts
+++ b/frontend/src/contexts/file/fileSelectors.ts
@@ -6,7 +6,9 @@ import { FileId } from '../../types/file';
 import {
   FileRecord,
   FileContextState,
-  FileContextSelectors
+  FileContextSelectors,
+  FileWithId,
+  createFileWithId
 } from '../../types/fileContext';
 
 /**
@@ -17,11 +19,19 @@ export function createFileSelectors(
   filesRef: React.MutableRefObject<Map<FileId, File>>
 ): FileContextSelectors {
   return {
-    getFile: (id: FileId) => filesRef.current.get(id),
+    getFile: (id: FileId) => {
+      const file = filesRef.current.get(id);
+      return file ? createFileWithId(file, id) : undefined;
+    },
 
     getFiles: (ids?: FileId[]) => {
       const currentIds = ids || stateRef.current.files.ids;
-      return currentIds.map(id => filesRef.current.get(id)).filter(Boolean) as File[];
+      return currentIds
+        .map(id => {
+          const file = filesRef.current.get(id);
+          return file ? createFileWithId(file, id) : undefined;
+        })
+        .filter(Boolean) as FileWithId[];
     },
 
     getFileRecord: (id: FileId) => stateRef.current.files.byId[id],
@@ -35,8 +45,11 @@ export function createFileSelectors(
 
     getSelectedFiles: () => {
       return stateRef.current.ui.selectedFileIds
-        .map(id => filesRef.current.get(id))
-        .filter(Boolean) as File[];
+        .map(id => {
+          const file = filesRef.current.get(id);
+          return file ? createFileWithId(file, id) : undefined;
+        })
+        .filter(Boolean) as FileWithId[];
     },
 
     getSelectedFileRecords: () => {
@@ -52,8 +65,11 @@ export function createFileSelectors(
 
     getPinnedFiles: () => {
       return Array.from(stateRef.current.pinnedFiles)
-        .map(id => filesRef.current.get(id))
-        .filter(Boolean) as File[];
+        .map(id => {
+          const file = filesRef.current.get(id);
+          return file ? createFileWithId(file, id) : undefined;
+        })
+        .filter(Boolean) as FileWithId[];
     },
 
     getPinnedFileRecords: () => {
@@ -62,16 +78,8 @@ export function createFileSelectors(
         .filter(Boolean);
     },
 
-    isFilePinned: (file: File) => {
-      // Find FileId by matching File object properties
-      const fileId = (Object.keys(stateRef.current.files.byId) as FileId[]).find(id => {
-        const storedFile = filesRef.current.get(id);
-        return storedFile &&
-               storedFile.name === file.name &&
-               storedFile.size === file.size &&
-               storedFile.lastModified === file.lastModified;
-      });
-      return fileId ? stateRef.current.pinnedFiles.has(fileId) : false;
+    isFilePinned: (file: FileWithId) => {
+      return stateRef.current.pinnedFiles.has(file.fileId);
     },
 
     // Stable signature for effects - prevents unnecessary re-renders
diff --git a/frontend/src/hooks/tools/shared/useBaseTool.ts b/frontend/src/hooks/tools/shared/useBaseTool.ts
index 64e9af59e..4995803e5 100644
--- a/frontend/src/hooks/tools/shared/useBaseTool.ts
+++ b/frontend/src/hooks/tools/shared/useBaseTool.ts
@@ -4,10 +4,11 @@ import { useEndpointEnabled } from '../../useEndpointConfig';
 import { BaseToolProps } from '../../../types/tool';
 import { ToolOperationHook } from './useToolOperation';
 import { BaseParametersHook } from './useBaseParameters';
+import { FileWithId } from '../../../types/fileContext';
 
 interface BaseToolReturn<TParams> {
   // File management
-  selectedFiles: File[];
+  selectedFiles: FileWithId[];
 
   // Tool-specific hooks
   params: BaseParametersHook<TParams>;
diff --git a/frontend/src/hooks/tools/shared/useToolOperation.ts b/frontend/src/hooks/tools/shared/useToolOperation.ts
index d8d35176d..03275b0e7 100644
--- a/frontend/src/hooks/tools/shared/useToolOperation.ts
+++ b/frontend/src/hooks/tools/shared/useToolOperation.ts
@@ -6,10 +6,8 @@ import { useToolState, type ProcessingProgress } from './useToolState';
 import { useToolApiCalls, type ApiCallsConfig } from './useToolApiCalls';
 import { useToolResources } from './useToolResources';
 import { extractErrorMessage } from '../../../utils/toolErrorHandler';
-import { createOperation } from '../../../utils/toolOperationTracker';
+import { FileWithId, extractFiles, FileId, FileRecord } from '../../../types/fileContext';
 import { ResponseHandler } from '../../../utils/toolResponseProcessor';
-import { FileId } from '../../../types/file';
-import { FileRecord } from '../../../types/fileContext';
 
 // Re-export for backwards compatibility
 export type { ProcessingProgress, ResponseHandler };
@@ -104,7 +102,7 @@ export interface ToolOperationHook<TParams = void> {
   progress: ProcessingProgress | null;
 
   // Actions
-  executeOperation: (params: TParams, selectedFiles: File[]) => Promise<void>;
+  executeOperation: (params: TParams, selectedFiles: FileWithId[]) => Promise<void>;
   resetResults: () => void;
   clearError: () => void;
   cancelOperation: () => void;
@@ -130,7 +128,7 @@ export const useToolOperation = <TParams>(
   config: ToolOperationConfig<TParams>
 ): ToolOperationHook<TParams> => {
   const { t } = useTranslation();
-  const { recordOperation, markOperationApplied, markOperationFailed, addFiles, consumeFiles, undoConsumeFiles, findFileId, actions: fileActions, selectors } = useFileContext();
+  const { addFiles, consumeFiles, undoConsumeFiles, actions: fileActions, selectors } = useFileContext();
 
   // Composed hooks
   const { state, actions } = useToolState();
@@ -146,7 +144,7 @@ export const useToolOperation = <TParams>(
 
   const executeOperation = useCallback(async (
     params: TParams,
-    selectedFiles: File[]
+    selectedFiles: FileWithId[]
   ): Promise<void> => {
     // Validation
     if (selectedFiles.length === 0) {
@@ -160,9 +158,6 @@ export const useToolOperation = <TParams>(
       return;
     }
 
-    // Setup operation tracking
-    const { operation, operationId, fileId } = createOperation(config.operationType, params, selectedFiles);
-    recordOperation(fileId, operation);
 
     // Reset state
     actions.setLoading(true);
@@ -173,6 +168,9 @@ export const useToolOperation = <TParams>(
     try {
       let processedFiles: File[];
 
+      // Convert FileWithId to regular File objects for API processing
+      const validRegularFiles = extractFiles(validFiles);
+
       switch (config.toolType) {
         case ToolType.singleFile:
           // Individual file processing - separate API call per file
@@ -184,7 +182,7 @@ export const useToolOperation = <TParams>(
           };
           processedFiles = await processFiles(
             params,
-            validFiles,
+            validRegularFiles,
             apiCallsConfig,
             actions.setProgress,
             actions.setStatus
@@ -194,7 +192,7 @@ export const useToolOperation = <TParams>(
         case ToolType.multiFile:
           // Multi-file processing - single API call with all files
           actions.setStatus('Processing files...');
-          const formData = config.buildFormData(params, validFiles);
+          const formData = config.buildFormData(params, validRegularFiles);
           const endpoint = typeof config.endpoint === 'function' ? config.endpoint(params) : config.endpoint;
 
           const response = await axios.post(endpoint, formData, { responseType: 'blob' });
@@ -202,11 +200,11 @@ export const useToolOperation = <TParams>(
           // Multi-file responses are typically ZIP files that need extraction, but some may return single PDFs
           if (config.responseHandler) {
             // Use custom responseHandler for multi-file (handles ZIP extraction)
-            processedFiles = await config.responseHandler(response.data, validFiles);
+            processedFiles = await config.responseHandler(response.data, validRegularFiles);
           } else if (response.data.type === 'application/pdf' ||
                      (response.headers && response.headers['content-type'] === 'application/pdf')) {
             // Single PDF response (e.g. split with merge option) - use original filename
-            const originalFileName = validFiles[0]?.name || 'document.pdf';
+            const originalFileName = validRegularFiles[0]?.name || 'document.pdf';
             const singleFile = new File([response.data], originalFileName, { type: 'application/pdf' });
             processedFiles = [singleFile];
           } else {
@@ -222,7 +220,7 @@ export const useToolOperation = <TParams>(
 
         case ToolType.custom:
           actions.setStatus('Processing files...');
-          processedFiles = await config.customProcessor(params, validFiles);
+          processedFiles = await config.customProcessor(params, validRegularFiles);
           break;
       }
 
@@ -246,17 +244,13 @@ export const useToolOperation = <TParams>(
         
         // Build parallel arrays of IDs and records for undo tracking
         for (const file of validFiles) {
-          const fileId = findFileId(file);
-          if (fileId) {
-            const record = selectors.getFileRecord(fileId);
-            if (record) {
-              inputFileIds.push(fileId);
-              inputFileRecords.push(record);
-            } else {
-              console.warn(`No file record found for file: ${file.name}`);
-            }
+          const fileId = file.fileId;
+          const record = selectors.getFileRecord(fileId);
+          if (record) {
+            inputFileIds.push(fileId);
+            inputFileRecords.push(record);
           } else {
-            console.warn(`No file ID found for file: ${file.name}`);
+            console.warn(`No file record found for file: ${file.name}`);
           }
         }
         
@@ -264,24 +258,22 @@ export const useToolOperation = <TParams>(
         
         // Store operation data for undo (only store what we need to avoid memory bloat)
         lastOperationRef.current = {
-          inputFiles: validFiles, // Keep original File objects for undo
+          inputFiles: extractFiles(validFiles), // Convert to File objects for undo
           inputFileRecords: inputFileRecords.map(record => ({ ...record })), // Deep copy to avoid reference issues
           outputFileIds
         };
 
-        markOperationApplied(fileId, operationId);
       }
 
     } catch (error: any) {
       const errorMessage = config.getErrorMessage?.(error) || extractErrorMessage(error);
       actions.setError(errorMessage);
       actions.setStatus('');
-      markOperationFailed(fileId, operationId, errorMessage);
     } finally {
       actions.setLoading(false);
       actions.setProgress(null);
     }
-  }, [t, config, actions, recordOperation, markOperationApplied, markOperationFailed, addFiles, consumeFiles, findFileId, processFiles, generateThumbnails, createDownloadInfo, cleanupBlobUrls, extractZipFiles, extractAllZipFiles]);
+  }, [t, config, actions, addFiles, consumeFiles, processFiles, generateThumbnails, createDownloadInfo, cleanupBlobUrls, extractZipFiles, extractAllZipFiles]);
 
   const cancelOperation = useCallback(() => {
     cancelApiCalls();
diff --git a/frontend/src/hooks/useFileManager.ts b/frontend/src/hooks/useFileManager.ts
index f47430fd2..8df1e2754 100644
--- a/frontend/src/hooks/useFileManager.ts
+++ b/frontend/src/hooks/useFileManager.ts
@@ -2,7 +2,7 @@ import { useState, useCallback } from 'react';
 import { useIndexedDB } from '../contexts/IndexedDBContext';
 import { FileMetadata } from '../types/file';
 import { generateThumbnailForFile } from '../utils/thumbnailUtils';
-import { FileId } from '../types/file';
+import { FileId } from '../types/fileContext';
 
 export const useFileManager = () => {
   const [loading, setLoading] = useState(false);
diff --git a/frontend/src/hooks/useFileWithUrl.ts b/frontend/src/hooks/useFileWithUrl.ts
index fd2f2d604..84c06baa2 100644
--- a/frontend/src/hooks/useFileWithUrl.ts
+++ b/frontend/src/hooks/useFileWithUrl.ts
@@ -1,4 +1,5 @@
 import { useMemo } from 'react';
+import { isFileObject } from '../types/fileContext';
 
 /**
  * Hook to convert a File object to { file: File; url: string } format
@@ -8,8 +9,8 @@ export function useFileWithUrl(file: File | Blob | null): { file: File | Blob; u
   return useMemo(() => {
     if (!file) return null;
 
-    // Validate that file is a proper File or Blob object
-    if (!(file instanceof File) && !(file instanceof Blob)) {
+    // Validate that file is a proper File, FileWithId, or Blob object
+    if (!isFileObject(file) && !(file instanceof Blob)) {
       console.warn('useFileWithUrl: Expected File or Blob, got:', file);
       return null;
     }
diff --git a/frontend/src/hooks/useIndexedDBThumbnail.ts b/frontend/src/hooks/useIndexedDBThumbnail.ts
index 4f0d77c0e..a6251db3c 100644
--- a/frontend/src/hooks/useIndexedDBThumbnail.ts
+++ b/frontend/src/hooks/useIndexedDBThumbnail.ts
@@ -2,6 +2,7 @@ import { useState, useEffect } from "react";
 import { FileMetadata } from "../types/file";
 import { useIndexedDB } from "../contexts/IndexedDBContext";
 import { generateThumbnailForFile } from "../utils/thumbnailUtils";
+import { FileId } from "../types/fileContext";
 
 /**
  * Calculate optimal scale for thumbnail generation
@@ -53,7 +54,7 @@ export function useIndexedDBThumbnail(file: FileMetadata | undefined | null): {
 
           // Try to load file from IndexedDB using new context
           if (file.id && indexedDB) {
-            const loadedFile = await indexedDB.loadFile(file.id);
+            const loadedFile = await indexedDB.loadFile(file.id as FileId);
             if (!loadedFile) {
               throw new Error('File not found in IndexedDB');
             }
@@ -70,7 +71,7 @@ export function useIndexedDBThumbnail(file: FileMetadata | undefined | null): {
             // Save thumbnail to IndexedDB for persistence
             if (file.id && indexedDB && thumbnail) {
               try {
-                await indexedDB.updateThumbnail(file.id, thumbnail);
+                await indexedDB.updateThumbnail(file.id as FileId, thumbnail);
               } catch (error) {
                 console.warn('Failed to save thumbnail to IndexedDB:', error);
               }
diff --git a/frontend/src/hooks/usePDFProcessor.ts b/frontend/src/hooks/usePDFProcessor.ts
index ab3b5e007..b88bfbe2b 100644
--- a/frontend/src/hooks/usePDFProcessor.ts
+++ b/frontend/src/hooks/usePDFProcessor.ts
@@ -1,6 +1,7 @@
 import { useState, useCallback } from 'react';
 import { PDFDocument, PDFPage } from '../types/pageEditor';
 import { pdfWorkerManager } from '../services/pdfWorkerManager';
+import { createQuickKey } from '../types/fileContext';
 
 export function usePDFProcessor() {
   const [loading, setLoading] = useState(false);
@@ -75,7 +76,7 @@ export function usePDFProcessor() {
       // Create pages without thumbnails initially - load them lazily
       for (let i = 1; i <= totalPages; i++) {
         pages.push({
-          id: `${file.name}-page-${i}`,
+          id: `${createQuickKey(file)}-page-${i}`,
           pageNumber: i,
           originalPageNumber: i,
           thumbnail: null, // Will be loaded lazily
diff --git a/frontend/src/hooks/usePdfSignatureDetection.ts b/frontend/src/hooks/usePdfSignatureDetection.ts
index 17f90f2d9..84075f972 100644
--- a/frontend/src/hooks/usePdfSignatureDetection.ts
+++ b/frontend/src/hooks/usePdfSignatureDetection.ts
@@ -1,13 +1,14 @@
 import { useState, useEffect } from 'react';
 import * as pdfjsLib from 'pdfjs-dist';
 import { pdfWorkerManager } from '../services/pdfWorkerManager';
+import { FileWithId } from '../types/fileContext';
 
 export interface PdfSignatureDetectionResult {
   hasDigitalSignatures: boolean;
   isChecking: boolean;
 }
 
-export const usePdfSignatureDetection = (files: File[]): PdfSignatureDetectionResult => {
+export const usePdfSignatureDetection = (files: FileWithId[]): PdfSignatureDetectionResult => {
   const [hasDigitalSignatures, setHasDigitalSignatures] = useState(false);
   const [isChecking, setIsChecking] = useState(false);
 
diff --git a/frontend/src/hooks/useThumbnailGeneration.ts b/frontend/src/hooks/useThumbnailGeneration.ts
index 8eba26214..310634045 100644
--- a/frontend/src/hooks/useThumbnailGeneration.ts
+++ b/frontend/src/hooks/useThumbnailGeneration.ts
@@ -1,5 +1,6 @@
 import { useCallback, useRef } from 'react';
 import { thumbnailGenerationService } from '../services/thumbnailGenerationService';
+import { createQuickKey } from '../types/fileContext';
 import { FileId } from '../types/file';
 
 // Request queue to handle concurrent thumbnail requests
@@ -71,8 +72,8 @@ async function processRequestQueue() {
 
           console.log(`📸 Batch generating ${requests.length} thumbnails for pages: ${pageNumbers.slice(0, 5).join(', ')}${pageNumbers.length > 5 ? '...' : ''}`);
 
-          // Use file name as fileId for PDF document caching
-          const fileId = file.name + '_' + file.size + '_' + file.lastModified as FileId;
+          // Use quickKey for PDF document caching (same metadata, consistent format)
+          const fileId = createQuickKey(file) as FileId;
 
           const results = await thumbnailGenerationService.generateThumbnails(
             fileId,
diff --git a/frontend/src/services/enhancedPDFProcessingService.ts b/frontend/src/services/enhancedPDFProcessingService.ts
index f9f067c30..2d4bf4644 100644
--- a/frontend/src/services/enhancedPDFProcessingService.ts
+++ b/frontend/src/services/enhancedPDFProcessingService.ts
@@ -5,6 +5,7 @@ import { FileHasher } from '../utils/fileHash';
 import { FileAnalyzer } from './fileAnalyzer';
 import { ProcessingErrorHandler } from './processingErrorHandler';
 import { pdfWorkerManager } from './pdfWorkerManager';
+import { createQuickKey } from '../types/fileContext';
 
 export class EnhancedPDFProcessingService {
   private static instance: EnhancedPDFProcessingService;
@@ -201,7 +202,7 @@ export class EnhancedPDFProcessingService {
         const thumbnail = await this.renderPageThumbnail(page, config.thumbnailQuality);
 
         pages.push({
-          id: `${file.name}-page-${i}`,
+          id: `${createQuickKey(file)}-page-${i}`,
           pageNumber: i,
           thumbnail,
           rotation: 0,
@@ -251,7 +252,7 @@ export class EnhancedPDFProcessingService {
       const thumbnail = await this.renderPageThumbnail(page, config.thumbnailQuality);
 
       pages.push({
-        id: `${file.name}-page-${i}`,
+        id: `${createQuickKey(file)}-page-${i}`,
         pageNumber: i,
         thumbnail,
         rotation: 0,
@@ -266,7 +267,7 @@ export class EnhancedPDFProcessingService {
     // Create placeholder pages for remaining pages
     for (let i = priorityCount + 1; i <= totalPages; i++) {
       pages.push({
-        id: `${file.name}-page-${i}`,
+        id: `${createQuickKey(file)}-page-${i}`,
         pageNumber: i,
         thumbnail: null, // Will be loaded lazily
         rotation: 0,
@@ -313,7 +314,7 @@ export class EnhancedPDFProcessingService {
       const thumbnail = await this.renderPageThumbnail(page, config.thumbnailQuality);
 
       pages.push({
-        id: `${file.name}-page-${i}`,
+        id: `${createQuickKey(file)}-page-${i}`,
         pageNumber: i,
         thumbnail,
         rotation: 0,
@@ -334,7 +335,7 @@ export class EnhancedPDFProcessingService {
     // Create placeholders for remaining pages
     for (let i = firstChunkEnd + 1; i <= totalPages; i++) {
       pages.push({
-        id: `${file.name}-page-${i}`,
+        id: `${createQuickKey(file)}-page-${i}`,
         pageNumber: i,
         thumbnail: null,
         rotation: 0,
@@ -368,7 +369,7 @@ export class EnhancedPDFProcessingService {
     const pages: PDFPage[] = [];
     for (let i = 1; i <= totalPages; i++) {
       pages.push({
-        id: `${file.name}-page-${i}`,
+        id: `${createQuickKey(file)}-page-${i}`,
         pageNumber: i,
         thumbnail: null,
         rotation: 0,
diff --git a/frontend/src/services/pdfProcessingService.ts b/frontend/src/services/pdfProcessingService.ts
index 065f53210..7ede9334d 100644
--- a/frontend/src/services/pdfProcessingService.ts
+++ b/frontend/src/services/pdfProcessingService.ts
@@ -1,6 +1,7 @@
 import { ProcessedFile, ProcessingState, PDFPage } from '../types/processing';
 import { ProcessingCache } from './processingCache';
 import { pdfWorkerManager } from './pdfWorkerManager';
+import { createQuickKey } from '../types/fileContext';
 
 export class PDFProcessingService {
   private static instance: PDFProcessingService;
@@ -113,7 +114,7 @@ export class PDFProcessingService {
         const thumbnail = canvas.toDataURL();
 
         pages.push({
-          id: `${file.name}-page-${i}`,
+          id: `${createQuickKey(file)}-page-${i}`,
           pageNumber: i,
           thumbnail,
           rotation: 0,
diff --git a/frontend/src/tests/convert/ConvertIntegration.test.tsx b/frontend/src/tests/convert/ConvertIntegration.test.tsx
index 41a768838..37a25c2a5 100644
--- a/frontend/src/tests/convert/ConvertIntegration.test.tsx
+++ b/frontend/src/tests/convert/ConvertIntegration.test.tsx
@@ -18,6 +18,8 @@ import { FileContextProvider } from '../../contexts/FileContext';
 import { I18nextProvider } from 'react-i18next';
 import i18n from '../../i18n/config';
 import axios from 'axios';
+import { createTestFileWithId } from '../utils/testFileHelpers';
+import { FileWithId } from '../../types/fileContext';
 
 // Mock axios
 vi.mock('axios');
@@ -55,9 +57,9 @@ const createTestFile = (name: string, content: string, type: string): File => {
   return new File([content], name, { type });
 };
 
-const createPDFFile = (): File => {
+const createPDFFile = (): FileWithId => {
   const pdfContent = '%PDF-1.4\n1 0 obj\n<<\n/Type /Catalog\n/Pages 2 0 R\n>>\nendobj\ntrailer\n<<\n/Size 2\n/Root 1 0 R\n>>\nstartxref\n0\n%%EOF';
-  return createTestFile('test.pdf', pdfContent, 'application/pdf');
+  return createTestFileWithId('test.pdf', pdfContent, 'application/pdf');
 };
 
 // Test wrapper component
@@ -162,7 +164,7 @@ describe('Convert Tool Integration Tests', () => {
         wrapper: TestWrapper
       });
 
-      const testFile = createTestFile('invalid.txt', 'not a pdf', 'text/plain');
+      const testFile = createTestFileWithId('invalid.txt', 'not a pdf', 'text/plain');
       const parameters: ConvertParameters = {
         fromExtension: 'pdf',
         toExtension: 'png',
@@ -426,7 +428,7 @@ describe('Convert Tool Integration Tests', () => {
       });
       const files = [
         createPDFFile(),
-        createTestFile('test2.pdf', '%PDF-1.4...', 'application/pdf')
+        createTestFileWithId('test2.pdf', '%PDF-1.4...', 'application/pdf')
       ]
       const parameters: ConvertParameters = {
         fromExtension: 'pdf',
@@ -527,7 +529,7 @@ describe('Convert Tool Integration Tests', () => {
         wrapper: TestWrapper
       });
 
-      const corruptedFile = createTestFile('corrupted.pdf', 'not-a-pdf', 'application/pdf');
+      const corruptedFile = createTestFileWithId('corrupted.pdf', 'not-a-pdf', 'application/pdf');
       const parameters: ConvertParameters = {
         fromExtension: 'pdf',
         toExtension: 'png',
diff --git a/frontend/src/tests/convert/ConvertSmartDetectionIntegration.test.tsx b/frontend/src/tests/convert/ConvertSmartDetectionIntegration.test.tsx
index 4e9fb7908..3ba6cc589 100644
--- a/frontend/src/tests/convert/ConvertSmartDetectionIntegration.test.tsx
+++ b/frontend/src/tests/convert/ConvertSmartDetectionIntegration.test.tsx
@@ -14,6 +14,8 @@ import i18n from '../../i18n/config';
 import axios from 'axios';
 import { detectFileExtension } from '../../utils/fileUtils';
 import { FIT_OPTIONS } from '../../constants/convertConstants';
+import { createTestFileWithId, createTestFilesWithId } from '../utils/testFileHelpers';
+import { FileWithId } from '../../types/fileContext';
 
 // Mock axios
 vi.mock('axios');
@@ -81,7 +83,7 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
       });
 
       // Create mock DOCX file
-      const docxFile = new File(['docx content'], 'document.docx', { type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' });
+      const docxFile = createTestFileWithId('document.docx', 'docx content', 'application/vnd.openxmlformats-officedocument.wordprocessingml.document');
 
       // Test auto-detection
       act(() => {
@@ -117,7 +119,7 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
       });
 
       // Create mock unknown file
-      const unknownFile = new File(['unknown content'], 'document.xyz', { type: 'application/octet-stream' });
+      const unknownFile = createTestFileWithId('document.xyz', 'unknown content', 'application/octet-stream');
 
       // Test auto-detection
       act(() => {
@@ -156,11 +158,11 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
       });
 
       // Create mock image files
-      const imageFiles = [
-        new File(['jpg content'], 'photo1.jpg', { type: 'image/jpeg' }),
-        new File(['png content'], 'photo2.png', { type: 'image/png' }),
-        new File(['gif content'], 'photo3.gif', { type: 'image/gif' })
-      ];
+      const imageFiles = createTestFilesWithId([
+        { name: 'photo1.jpg', content: 'jpg content', type: 'image/jpeg' },
+        { name: 'photo2.png', content: 'png content', type: 'image/png' },
+        { name: 'photo3.gif', content: 'gif content', type: 'image/gif' }
+      ]);
 
       // Test smart detection for all images
       act(() => {
@@ -202,11 +204,11 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
       });
 
       // Create mixed file types
-      const mixedFiles = [
-        new File(['pdf content'], 'document.pdf', { type: 'application/pdf' }),
-        new File(['docx content'], 'spreadsheet.xlsx', { type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' }),
-        new File(['pptx content'], 'presentation.pptx', { type: 'application/vnd.openxmlformats-officedocument.presentationml.presentation' })
-      ];
+      const mixedFiles = createTestFilesWithId([
+        { name: 'document.pdf', content: 'pdf content', type: 'application/pdf' },
+        { name: 'spreadsheet.xlsx', content: 'docx content', type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' },
+        { name: 'presentation.pptx', content: 'pptx content', type: 'application/vnd.openxmlformats-officedocument.presentationml.presentation' }
+      ]);
 
       // Test smart detection for mixed types
       act(() => {
@@ -243,10 +245,10 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
       });
 
       // Create mock web files
-      const webFiles = [
-        new File(['<html>content</html>'], 'page1.html', { type: 'text/html' }),
-        new File(['zip content'], 'site.zip', { type: 'application/zip' })
-      ];
+      const webFiles = createTestFilesWithId([
+        { name: 'page1.html', content: '<html>content</html>', type: 'text/html' },
+        { name: 'site.zip', content: 'zip content', type: 'application/zip' }
+      ]);
 
       // Test smart detection for web files
       act(() => {
@@ -288,7 +290,7 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
         wrapper: TestWrapper
       });
 
-      const htmlFile = new File(['<html>content</html>'], 'page.html', { type: 'text/html' });
+      const htmlFile = createTestFileWithId('page.html', '<html>content</html>', 'text/html');
 
       // Set up HTML conversion parameters
       act(() => {
@@ -318,7 +320,7 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
         wrapper: TestWrapper
       });
 
-      const emlFile = new File(['email content'], 'email.eml', { type: 'message/rfc822' });
+      const emlFile = createTestFileWithId('email.eml', 'email content', 'message/rfc822');
 
       // Set up email conversion parameters
       act(() => {
@@ -355,7 +357,7 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
         wrapper: TestWrapper
       });
 
-      const pdfFile = new File(['pdf content'], 'document.pdf', { type: 'application/pdf' });
+      const pdfFile = createTestFileWithId('document.pdf', 'pdf content', 'application/pdf');
 
       // Set up PDF/A conversion parameters
       act(() => {
@@ -392,10 +394,10 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
         wrapper: TestWrapper
       });
 
-      const imageFiles = [
-        new File(['jpg1'], 'photo1.jpg', { type: 'image/jpeg' }),
-        new File(['jpg2'], 'photo2.jpg', { type: 'image/jpeg' })
-      ];
+      const imageFiles = createTestFilesWithId([
+        { name: 'photo1.jpg', content: 'jpg1', type: 'image/jpeg' },
+        { name: 'photo2.jpg', content: 'jpg2', type: 'image/jpeg' }
+      ]);
 
       // Set up image conversion parameters
       act(() => {
@@ -432,10 +434,10 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
         wrapper: TestWrapper
       });
 
-      const imageFiles = [
-        new File(['jpg1'], 'photo1.jpg', { type: 'image/jpeg' }),
-        new File(['jpg2'], 'photo2.jpg', { type: 'image/jpeg' })
-      ];
+      const imageFiles = createTestFilesWithId([
+        { name: 'photo1.jpg', content: 'jpg1', type: 'image/jpeg' },
+        { name: 'photo2.jpg', content: 'jpg2', type: 'image/jpeg' }
+      ]);
 
       // Set up for separate processing
       act(() => {
@@ -477,10 +479,10 @@ describe('Convert Tool - Smart Detection Integration Tests', () => {
         })
         .mockRejectedValueOnce(new Error('File 2 failed'));
 
-      const mixedFiles = [
-        new File(['file1'], 'doc1.txt', { type: 'text/plain' }),
-        new File(['file2'], 'doc2.xyz', { type: 'application/octet-stream' })
-      ];
+      const mixedFiles = createTestFilesWithId([
+        { name: 'doc1.txt', content: 'file1', type: 'text/plain' },
+        { name: 'doc2.xyz', content: 'file2', type: 'application/octet-stream' }
+      ]);
 
       // Set up for separate processing (mixed smart detection)
       act(() => {
diff --git a/frontend/src/tests/utils/testFileHelpers.ts b/frontend/src/tests/utils/testFileHelpers.ts
new file mode 100644
index 000000000..be8cd9774
--- /dev/null
+++ b/frontend/src/tests/utils/testFileHelpers.ts
@@ -0,0 +1,28 @@
+/**
+ * Test utilities for creating FileWithId objects in tests
+ */
+
+import { FileWithId, createFileWithId } from '../../types/fileContext';
+
+/**
+ * Create a FileWithId object for testing purposes
+ */
+export function createTestFileWithId(
+  name: string,
+  content: string = 'test content',
+  type: string = 'application/pdf'
+): FileWithId {
+  const file = new File([content], name, { type });
+  return createFileWithId(file);
+}
+
+/**
+ * Create multiple FileWithId objects for testing
+ */
+export function createTestFilesWithId(
+  files: Array<{ name: string; content?: string; type?: string }>
+): FileWithId[] {
+  return files.map(({ name, content = 'test content', type = 'application/pdf' }) =>
+    createTestFileWithId(name, content, type)
+  );
+}
\ No newline at end of file
diff --git a/frontend/src/types/fileContext.ts b/frontend/src/types/fileContext.ts
index 9210f9ce9..5520e2cde 100644
--- a/frontend/src/types/fileContext.ts
+++ b/frontend/src/types/fileContext.ts
@@ -5,6 +5,9 @@
 import { PageOperation } from './pageEditor';
 import { FileId, FileMetadata } from './file';
 
+// Re-export FileId for convenience
+export type { FileId };
+
 export type ModeType =
   | 'viewer'
   | 'pageEditor'
@@ -82,6 +85,67 @@ export function createQuickKey(file: File): string {
   return `${file.name}|${file.size}|${file.lastModified}`;
 }
 
+// File with embedded UUID - replaces loose File + FileId parameter passing
+export interface FileWithId extends File {
+  readonly fileId: FileId;
+  readonly quickKey: string; // Fast deduplication key: name|size|lastModified
+}
+
+// Type guard to check if a File object has an embedded fileId
+export function isFileWithId(file: File): file is FileWithId {
+  return 'fileId' in file && typeof (file as any).fileId === 'string' &&
+         'quickKey' in file && typeof (file as any).quickKey === 'string';
+}
+
+// Create a FileWithId from a regular File object
+export function createFileWithId(file: File, id?: FileId): FileWithId {
+  const fileId = id || createFileId();
+  const quickKey = createQuickKey(file);
+  
+  // File properties are not enumerable, so we need to copy them explicitly
+  // This avoids prototype chain issues while preserving all File functionality
+  const fileWithId = {
+    // Explicitly copy File properties (they're not enumerable)
+    name: file.name,
+    size: file.size,
+    type: file.type,
+    lastModified: file.lastModified,
+    webkitRelativePath: file.webkitRelativePath,
+    
+    // Add our custom properties
+    fileId: fileId,
+    quickKey: quickKey,
+    
+    // Preserve File prototype methods by binding them to the original file
+    arrayBuffer: file.arrayBuffer.bind(file),
+    slice: file.slice.bind(file),
+    stream: file.stream.bind(file),
+    text: file.text.bind(file)
+  } as FileWithId;
+  
+  return fileWithId;
+}
+
+// Extract FileIds from FileWithId array
+export function extractFileIds(files: FileWithId[]): FileId[] {
+  return files.map(file => file.fileId);
+}
+
+// Extract regular File objects from FileWithId array
+export function extractFiles(files: FileWithId[]): File[] {
+  return files as File[];
+}
+
+// Check if an object is a File or FileWithId (replaces instanceof File checks)
+export function isFileObject(obj: any): obj is File | FileWithId {
+  return obj && 
+         typeof obj.name === 'string' &&
+         typeof obj.size === 'number' &&
+         typeof obj.type === 'string' &&
+         typeof obj.lastModified === 'number' &&
+         typeof obj.arrayBuffer === 'function';
+}
+
 
 
 export function toFileRecord(file: File, id?: FileId): FileRecord {
@@ -215,18 +279,18 @@ export type FileContextAction =
 
 export interface FileContextActions {
   // File management - lightweight actions only
-  addFiles: (files: File[], options?: { insertAfterPageId?: string; selectFiles?: boolean }) => Promise<File[]>;
-  addProcessedFiles: (filesWithThumbnails: Array<{ file: File; thumbnail?: string; pageCount?: number }>) => Promise<File[]>;
-  addStoredFiles: (filesWithMetadata: Array<{ file: File; originalId: FileId; metadata: FileMetadata }>, options?: { selectFiles?: boolean }) => Promise<File[]>;
+  addFiles: (files: File[], options?: { insertAfterPageId?: string; selectFiles?: boolean }) => Promise<FileWithId[]>;
+  addProcessedFiles: (filesWithThumbnails: Array<{ file: File; thumbnail?: string; pageCount?: number }>) => Promise<FileWithId[]>;
+  addStoredFiles: (filesWithMetadata: Array<{ file: File; originalId: FileId; metadata: FileMetadata }>, options?: { selectFiles?: boolean }) => Promise<FileWithId[]>;
   removeFiles: (fileIds: FileId[], deleteFromStorage?: boolean) => Promise<void>;
   updateFileRecord: (id: FileId, updates: Partial<FileRecord>) => void;
   reorderFiles: (orderedFileIds: FileId[]) => void;
   clearAllFiles: () => Promise<void>;
   clearAllData: () => Promise<void>;
 
-  // File pinning
-  pinFile: (file: File) => void;
-  unpinFile: (file: File) => void;
+  // File pinning - accepts FileWithId for safer type checking
+  pinFile: (file: FileWithId) => void;
+  unpinFile: (file: FileWithId) => void;
 
   // File consumption (replace unpinned files with outputs)
   consumeFiles: (inputFileIds: FileId[], outputFiles: File[]) => Promise<FileId[]>;
@@ -253,26 +317,17 @@ export interface FileContextActions {
 
 // File selectors (separate from actions to avoid re-renders)
 export interface FileContextSelectors {
-  // File access - no state dependency, uses ref
-  getFile: (id: FileId) => File | undefined;
-  getFiles: (ids?: FileId[]) => File[];
-
-  // Record access - uses normalized state
+  getFile: (id: FileId) => FileWithId | undefined;
+  getFiles: (ids?: FileId[]) => FileWithId[];
   getFileRecord: (id: FileId) => FileRecord | undefined;
   getFileRecords: (ids?: FileId[]) => FileRecord[];
-
-  // Derived selectors
   getAllFileIds: () => FileId[];
-  getSelectedFiles: () => File[];
+  getSelectedFiles: () => FileWithId[];
   getSelectedFileRecords: () => FileRecord[];
-
-  // Pinned files selectors
   getPinnedFileIds: () => FileId[];
-  getPinnedFiles: () => File[];
+  getPinnedFiles: () => FileWithId[];
   getPinnedFileRecords: () => FileRecord[];
-  isFilePinned: (file: File) => boolean;
-
-  // Stable signature for effect dependencies
+  isFilePinned: (file: FileWithId) => boolean;
   getFilesSignature: () => string;
 }
 
diff --git a/frontend/src/types/fileIdSafety.d.ts b/frontend/src/types/fileIdSafety.d.ts
new file mode 100644
index 000000000..3235d3b3a
--- /dev/null
+++ b/frontend/src/types/fileIdSafety.d.ts
@@ -0,0 +1,50 @@
+/**
+ * Type safety declarations to prevent file.name/UUID confusion
+ */
+
+import { FileId, FileWithId, OperationType, FileOperation } from './fileContext';
+
+declare global {
+  namespace FileIdSafety {
+    // Mark functions that should never accept file.name as parameters
+    type SafeFileIdFunction<T extends (...args: any[]) => any> = T extends (...args: infer P) => infer R
+      ? P extends readonly [string, ...any[]]
+        ? never // Reject string parameters in first position for FileId functions
+        : T
+      : T;
+
+    // Mark functions that should only accept FileWithId, not regular File
+    type FileWithIdOnlyFunction<T extends (...args: any[]) => any> = T extends (...args: infer P) => infer R
+      ? P extends readonly [File, ...any[]]
+        ? never // Reject File parameters in first position for FileWithId functions
+        : T
+      : T;
+
+    // Utility type to enforce FileWithId usage
+    type RequireFileWithId<T> = T extends File ? FileWithId : T;
+  }
+
+  // Extend Window interface to add runtime validation helpers
+  interface Window {
+    __FILE_ID_DEBUG?: boolean;
+    __validateFileId?: (id: string, context: string) => void;
+  }
+}
+
+// Augment FileContext types to prevent bypassing FileWithId
+declare module '../contexts/FileContext' {
+  export interface StrictFileContextActions {
+    pinFile: (file: FileWithId) => void; // Must be FileWithId
+    unpinFile: (file: FileWithId) => void; // Must be FileWithId
+    addFiles: (files: File[], options?: { insertAfterPageId?: string }) => Promise<FileWithId[]>; // Returns FileWithId
+    consumeFiles: (inputFileIds: FileId[], outputFiles: File[]) => Promise<FileWithId[]>; // Returns FileWithId
+  }
+  
+  export interface StrictFileContextSelectors {
+    getFile: (id: FileId) => FileWithId | undefined; // Returns FileWithId
+    getFiles: (ids?: FileId[]) => FileWithId[]; // Returns FileWithId[]
+    isFilePinned: (file: FileWithId) => boolean; // Must be FileWithId
+  }
+}
+
+export {};
\ No newline at end of file
diff --git a/frontend/src/utils/fileIdSafety.ts b/frontend/src/utils/fileIdSafety.ts
new file mode 100644
index 000000000..6837786ed
--- /dev/null
+++ b/frontend/src/utils/fileIdSafety.ts
@@ -0,0 +1,79 @@
+/**
+ * Runtime validation utilities for FileId safety
+ */
+
+import { FileId } from '../types/fileContext';
+
+// Validate that a string is a proper FileId (has UUID format)
+export function isValidFileId(id: string): id is FileId {
+  // Check UUID v4 format: 8-4-4-4-12 hex digits
+  const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
+  return uuidRegex.test(id);
+}
+
+// Detect potentially dangerous file.name usage as ID
+export function isDangerousFileNameAsId(fileName: string, context: string = ''): boolean {
+  // Check if it's definitely a UUID (safe)
+  if (isValidFileId(fileName)) {
+    return false;
+  }
+  
+  // Check if it's a quickKey (safe) - format: name|size|lastModified
+  if (/^.+\|\d+\|\d+$/.test(fileName)) {
+    return false; // quickKeys are legitimate, not dangerous
+  }
+  
+  // Common patterns that suggest file.name is being used as ID
+  const dangerousPatterns = [
+    /^[^-]+-page-\d+$/, // pattern: filename-page-123
+    /\.(pdf|jpg|png|doc|docx)$/i, // ends with file extension
+    /\s/, // contains whitespace (filenames often have spaces)
+    /[()[\]{}]/, // contains brackets/parentheses common in filenames
+    /['"]/, // contains quotes
+    /[^a-zA-Z0-9\-._]/ // contains special characters not in UUIDs
+  ];
+  
+  // Check dangerous patterns
+  const isDangerous = dangerousPatterns.some(pattern => pattern.test(fileName));
+  
+  if (isDangerous && context) {
+    console.warn(`⚠️ Potentially dangerous file.name usage detected in ${context}: "${fileName}"`);
+  }
+  
+  return isDangerous;
+}
+
+// Runtime validation for FileId usage in development
+export function validateFileId(id: string, context: string): void {
+  if (process.env.NODE_ENV === 'development') {
+    // Check if it looks like a dangerous file.name usage
+    if (isDangerousFileNameAsId(id, context)) {
+      console.error(`💀 DANGEROUS: file.name used as FileId in ${context}! This will cause ID collisions.`);
+      console.trace('Stack trace:');
+    }
+  }
+}
+
+// Runtime validation for File vs FileWithId usage
+export function validateFileWithId(file: File, context: string): void {
+  // Check if file has embedded fileId
+  if (!('fileId' in file)) {
+    console.warn(`⚠️ Regular File object used where FileWithId expected in ${context}: "${file.name}"`);
+    console.warn('Consider using FileWithId for better type safety');
+  }
+}
+
+// Assertion for FileId validation (throws in development)
+export function assertValidFileId(id: string, context: string): void {
+  if (process.env.NODE_ENV === 'development') {
+    if (isDangerousFileNameAsId(id, context)) {
+      throw new Error(`ASSERTION FAILED: Dangerous file.name as FileId detected in ${context}: "${id}"`);
+    }
+  }
+}
+
+// Global debug helpers (can be enabled in dev tools)
+if (typeof window !== 'undefined') {
+  window.__FILE_ID_DEBUG = process.env.NODE_ENV === 'development';
+  window.__validateFileId = validateFileId;
+}
\ No newline at end of file