feat(25-00): add shared types, validators, and test stubs for file system

- Add ChatFile, ChatFileReference, ChatFileUploadResponse, ChatFileListResponse interfaces to types/chat.ts
- Add optional files?: ChatFile[] field to ChatMessage interface
- Add uploadChatFileSchema and createFileReferenceSchema Zod validators to validators/chat.ts
- Re-export all new types and validators from shared/src/index.ts
- Create test stubs for chat-file-service.test.ts and chat-file-routes.test.ts with it.todo() entries

packages/shared/src/index.ts

@@ -564,12 +564,16 @@ export {
   handoffSchema,
   searchMessagesSchema,
   branchConversationSchema,
+  uploadChatFileSchema,
+  createFileReferenceSchema,
   type CreateConversation,
   type UpdateConversation,
   type CreateMessage,
   type Handoff,
   type SearchMessages,
   type BranchConversation,
+  type UploadChatFile,
+  type CreateFileReference,
 } from "./validators/index.js";
 
 export type {
@@ -584,6 +588,10 @@ export type {
   ChatBookmarkWithMessage,
   ChatBookmarkListResponse,
   ChatBookmarkToggleResponse,
+  ChatFile,
+  ChatFileReference,
+  ChatFileUploadResponse,
+  ChatFileListResponse,
 } from "./types/chat.js";
 
 export { API_PREFIX, API } from "./api.js";

packages/shared/src/types/chat.ts

@@ -25,6 +25,41 @@ export interface ChatConversationListItem {
   branchFromMessageId: string | null;
 }
 
+export interface ChatFile {
+  id: string;
+  companyId: string;
+  conversationId: string | null;
+  messageId: string | null;
+  filename: string;
+  originalFilename: string;
+  mimeType: string;
+  sizeBytes: number;
+  objectKey: string;
+  sha256: string;
+  source: "user_upload" | "agent_generated";
+  category: "image" | "document" | "code" | "other" | null;
+  projectId: string | null;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface ChatFileReference {
+  id: string;
+  fileId: string;
+  conversationId: string;
+  messageId: string | null;
+  createdAt: string;
+}
+
+export interface ChatFileUploadResponse {
+  file: ChatFile;
+  contentPath: string;
+}
+
+export interface ChatFileListResponse {
+  items: ChatFile[];
+}
+
 export interface ChatMessage {
   id: string;
   conversationId: string;
@@ -34,6 +69,7 @@ export interface ChatMessage {
   messageType: string | null;
   createdAt: string;
   updatedAt: string | null;
+  files?: ChatFile[];
 }
 
 export interface ChatConversationListResponse {

packages/shared/src/validators/chat.ts

@@ -45,3 +45,18 @@ export const branchConversationSchema = z.object({
 
 export type SearchMessages = z.infer<typeof searchMessagesSchema>;
 export type BranchConversation = z.infer<typeof branchConversationSchema>;
+
+export const uploadChatFileSchema = z.object({
+  conversationId: z.string().uuid().optional(),
+  messageId: z.string().uuid().optional(),
+  source: z.enum(["user_upload", "agent_generated"]).default("user_upload"),
+  projectId: z.string().uuid().optional(),
+});
+
+export const createFileReferenceSchema = z.object({
+  fileId: z.string().uuid(),
+  messageId: z.string().uuid().optional(),
+});
+
+export type UploadChatFile = z.infer<typeof uploadChatFileSchema>;
+export type CreateFileReference = z.infer<typeof createFileReferenceSchema>;

server/src/__tests__/chat-file-routes.test.ts

@@ -0,0 +1,10 @@
+import { describe, it } from "vitest";
+
+describe("chatFileRoutes", () => {
+  it.todo("POST /conversations/:id/files uploads a file and returns 201");
+  it.todo("GET /conversations/:id/files lists files for conversation");
+  it.todo("GET /files/:fileId/content serves file content");
+  it.todo("POST /files/:fileId/references creates a cross-conversation reference");
+  it.todo("rejects upload when file exceeds size limit");
+  it.todo("rejects upload when content type is not allowed");
+});

server/src/__tests__/chat-file-service.test.ts

@@ -0,0 +1,9 @@
+import { describe, it } from "vitest";
+
+describe("chatFileService", () => {
+  it.todo("creates a file record after upload");
+  it.todo("lists files for a conversation");
+  it.todo("lists files for a message");
+  it.todo("creates a file reference in another conversation");
+  it.todo("returns file with contentPath");
+});