🧷 fix: Bind Agent File Context to Current Turn (#13506)

* fix: Bind agent file context to current turn

* fix: Avoid duplicating agent file context

* fix: Export agent file context prepender

* test: Use exported file context prepender

* fix: Keep file context transient for memory and counts

packages/api/src/agents/client.spec.ts

@@ -0,0 +1,54 @@
+import { ContentTypes } from 'librechat-data-provider';
+import { prependFileContext, type FormattedMessageWithContent } from './client';
+
+describe('prependFileContext', () => {
+  it('prepends file context to string content', () => {
+    const message: FormattedMessageWithContent = { content: 'Answer this question.' };
+
+    prependFileContext(message, 'Attached file text');
+
+    expect(message.content).toBe('Attached file text\nAnswer this question.');
+  });
+
+  it('prepends file context to the first text content part', () => {
+    const message: FormattedMessageWithContent = {
+      content: [
+        { type: ContentTypes.IMAGE_URL, image_url: { url: 'data:image/png;base64,abc' } },
+        { type: ContentTypes.TEXT, text: 'Answer this question.' },
+      ],
+    };
+
+    prependFileContext(message, 'Attached file text');
+
+    expect(Array.isArray(message.content)).toBe(true);
+    if (!Array.isArray(message.content)) {
+      throw new Error('Expected array content');
+    }
+    expect(message.content[1].text).toBe('Attached file text\nAnswer this question.');
+    expect(message.content[0]).toEqual({
+      type: ContentTypes.IMAGE_URL,
+      image_url: { url: 'data:image/png;base64,abc' },
+    });
+  });
+
+  it('adds a text content part when an array has no text part', () => {
+    const message: FormattedMessageWithContent = {
+      content: [{ type: ContentTypes.IMAGE_URL, image_url: { url: 'data:image/png;base64,abc' } }],
+    };
+
+    prependFileContext(message, 'Attached file text');
+
+    expect(message.content).toEqual([
+      { type: ContentTypes.TEXT, text: 'Attached file text' },
+      { type: ContentTypes.IMAGE_URL, image_url: { url: 'data:image/png;base64,abc' } },
+    ]);
+  });
+
+  it('leaves content unchanged when file context is empty', () => {
+    const message: FormattedMessageWithContent = { content: 'Answer this question.' };
+
+    prependFileContext(message, '');
+
+    expect(message.content).toBe('Answer this question.');
+  });
+});

packages/api/src/agents/client.ts

@@ -56,6 +56,42 @@ type ContentBlock = {
   tool_call?: { name?: string; args?: string; output?: string };
 };
 
+export type FormattedMessageContentPart = {
+  type?: string;
+  text?: string;
+  [key: string]: unknown;
+};
+
+export type FormattedMessageWithContent = {
+  content?: string | FormattedMessageContentPart[];
+};
+
+export function prependFileContext(
+  formattedMessage: FormattedMessageWithContent,
+  fileContext?: string | null,
+): void {
+  if (!fileContext) {
+    return;
+  }
+
+  if (typeof formattedMessage.content === 'string') {
+    formattedMessage.content = `${fileContext}\n${formattedMessage.content}`;
+    return;
+  }
+
+  if (!Array.isArray(formattedMessage.content)) {
+    return;
+  }
+
+  const textPart = formattedMessage.content.find((part) => part.type === ContentTypes.TEXT);
+  if (textPart != null && typeof textPart.text === 'string') {
+    textPart.text = `${fileContext}\n${textPart.text}`;
+    return;
+  }
+
+  formattedMessage.content.unshift({ type: ContentTypes.TEXT, text: fileContext });
+}
+
 function estimateImageDataTokens(data: string, isClaude: boolean): number {
   const dims = extractImageDimensions(data);
   if (dims == null) {