⚗️ refactor: Provider File Validation with Configurable Size Limits (#10405)

* chore: correct type for ServerRequest

* chore: improve ServerRequest typing across several modules

* feat: Add PDF configured limit validation

- Introduced comprehensive tests for PDF validation across multiple providers, ensuring correct behavior for file size limits and edge cases.
- Enhanced the `validatePdf` function to accept an optional configured file size limit, allowing for stricter validation based on user configurations.
- Updated related functions to utilize the new validation logic, ensuring consistent behavior across different providers.

* chore: Update Request type to ServerRequest in audio and video encoding modules

* refactor: move `getConfiguredFileSizeLimit` utility

* feat: Add video and audio validation with configurable size limits

- Introduced `validateVideo` and `validateAudio` functions to validate media files against provider-specific size limits.
- Enhanced validation logic to consider optional configured file size limits, allowing for more flexible file handling.
- Added comprehensive tests for video and audio validation across different providers, ensuring correct behavior for various scenarios.

* refactor: Update PDF and media validation to allow higher configured limits

- Modified validation logic to accept user-configured file size limits that exceed provider defaults, ensuring correct acceptance of files within the specified range.
- Updated tests to reflect changes in validation behavior, confirming that files are accepted when within the configured limits.
- Enhanced documentation in tests to clarify expected outcomes with the new validation rules.

* chore: Add @types/node-fetch dependency to package.json and package-lock.json

- Included the @types/node-fetch package to enhance type definitions for node-fetch usage.
- Updated package-lock.json to reflect the addition of the new dependency.

* fix: Rename FileConfigInput to TFileConfig

packages/api/src/files/encode/utils.ts

@@ -1,8 +1,26 @@
 import getStream from 'get-stream';
-import { FileSources } from 'librechat-data-provider';
+import { Providers } from '@librechat/agents';
+import { FileSources, mergeFileConfig } from 'librechat-data-provider';
 import type { IMongoFile } from '@librechat/data-schemas';
-import type { Request } from 'express';
-import type { StrategyFunctions, ProcessedFile } from '~/types/files';
+import type { ServerRequest, StrategyFunctions, ProcessedFile } from '~/types';
+
+/**
+ * Extracts the configured file size limit for a specific provider from fileConfig
+ * @param req - The server request object containing config
+ * @param provider - The provider to get the limit for
+ * @returns The configured file size limit in bytes, or undefined if not configured
+ */
+export const getConfiguredFileSizeLimit = (
+  req: ServerRequest,
+  provider: Providers,
+): number | undefined => {
+  if (!req.config?.fileConfig) {
+    return undefined;
+  }
+  const fileConfig = mergeFileConfig(req.config.fileConfig);
+  const endpointConfig = fileConfig.endpoints[provider] ?? fileConfig.endpoints.default;
+  return endpointConfig?.fileSizeLimit;
+};
 
 /**
  * Processes a file by downloading and encoding it to base64
@@ -13,7 +31,7 @@ import type { StrategyFunctions, ProcessedFile } from '~/types/files';
  * @returns Processed file with content and metadata, or null if filepath missing
  */
 export async function getFileStream(
-  req: Request,
+  req: ServerRequest,
   file: IMongoFile,
   encodingMethods: Record<string, StrategyFunctions>,
   getStrategyFunctions: (source: string) => StrategyFunctions,