diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index ca5d16af..9e7906bf 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -593,10 +593,14 @@ export {
   updateConversationSchema,
   createMessageSchema,
   handoffSchema,
+  searchMessagesSchema,
+  branchConversationSchema,
   type CreateConversation,
   type UpdateConversation,
   type CreateMessage,
   type Handoff,
+  type SearchMessages,
+  type BranchConversation,
 } from "./validators/index.js";
 
 export type {
@@ -605,6 +609,12 @@ export type {
   ChatMessage,
   ChatConversationListResponse,
   ChatMessageListResponse,
+  ChatMessageSearchResult,
+  ChatMessageSearchResponse,
+  ChatBookmark,
+  ChatBookmarkWithMessage,
+  ChatBookmarkListResponse,
+  ChatBookmarkToggleResponse,
 } from "./types/chat.js";
 
 export { API_PREFIX, API } from "./api.js";
diff --git a/packages/shared/src/types/chat.ts b/packages/shared/src/types/chat.ts
index bd97469b..b015cd1b 100644
--- a/packages/shared/src/types/chat.ts
+++ b/packages/shared/src/types/chat.ts
@@ -8,6 +8,8 @@ export interface ChatConversation {
   deletedAt: string | null;
   createdAt: string;
   updatedAt: string;
+  parentConversationId: string | null;
+  branchFromMessageId: string | null;
 }
 
 export interface ChatConversationListItem {
@@ -19,6 +21,8 @@ export interface ChatConversationListItem {
   archivedAt: string | null;
   updatedAt: string;
   lastMessagePreview: string | null;
+  parentConversationId: string | null;
+  branchFromMessageId: string | null;
 }
 
 export interface ChatMessage {
@@ -41,3 +45,39 @@ export interface ChatMessageListResponse {
   items: ChatMessage[];
   hasMore: boolean;
 }
+
+export interface ChatMessageSearchResult {
+  messageId: string;
+  conversationId: string;
+  conversationTitle: string | null;
+  content: string;
+  role: "user" | "assistant" | "system";
+  agentId: string | null;
+  createdAt: string;
+  rank: number;
+}
+
+export interface ChatMessageSearchResponse {
+  items: ChatMessageSearchResult[];
+}
+
+export interface ChatBookmark {
+  id: string;
+  companyId: string;
+  messageId: string;
+  conversationId: string;
+  createdAt: string;
+}
+
+export interface ChatBookmarkWithMessage extends ChatBookmark {
+  message: ChatMessage;
+  conversationTitle: string | null;
+}
+
+export interface ChatBookmarkListResponse {
+  items: ChatBookmarkWithMessage[];
+}
+
+export interface ChatBookmarkToggleResponse {
+  bookmarked: boolean;
+}
diff --git a/packages/shared/src/validators/chat.ts b/packages/shared/src/validators/chat.ts
index b7a5a3b0..91a17f5c 100644
--- a/packages/shared/src/validators/chat.ts
+++ b/packages/shared/src/validators/chat.ts
@@ -33,3 +33,15 @@ export type CreateConversation = z.infer<typeof createConversationSchema>;
 export type UpdateConversation = z.infer<typeof updateConversationSchema>;
 export type CreateMessage = z.infer<typeof createMessageSchema>;
 export type Handoff = z.infer<typeof handoffSchema>;
+
+export const searchMessagesSchema = z.object({
+  q: z.string().min(2).max(200),
+  limit: z.coerce.number().int().min(1).max(50).optional(),
+});
+
+export const branchConversationSchema = z.object({
+  branchFromMessageId: z.string().uuid(),
+});
+
+export type SearchMessages = z.infer<typeof searchMessagesSchema>;
+export type BranchConversation = z.infer<typeof branchConversationSchema>;
diff --git a/server/src/__tests__/chat-routes.test.ts b/server/src/__tests__/chat-routes.test.ts
index 6b161fdb..02dcbeca 100644
--- a/server/src/__tests__/chat-routes.test.ts
+++ b/server/src/__tests__/chat-routes.test.ts
@@ -196,4 +196,22 @@ describe("chatRoutes", () => {
       );
     });
   });
+
+  describe("GET /companies/:id/messages/search", () => {
+    it.todo("returns 200 with search results");
+    it.todo("returns 400 for short query");
+  });
+
+  describe("POST /conversations/:id/bookmarks", () => {
+    it.todo("toggles bookmark on/off");
+  });
+
+  describe("POST /conversations/:id/branch", () => {
+    it.todo("returns 201 with branched conversation");
+  });
+
+  describe("GET /conversations/:id/export", () => {
+    it.todo("returns markdown file download");
+    it.todo("returns JSON file download");
+  });
 });
diff --git a/server/src/__tests__/chat-service.test.ts b/server/src/__tests__/chat-service.test.ts
index 0bd46e99..eae6da19 100644
--- a/server/src/__tests__/chat-service.test.ts
+++ b/server/src/__tests__/chat-service.test.ts
@@ -383,4 +383,25 @@ describe("chatService", () => {
       expect(result.items.length).toBe(50);
     });
   });
+
+  describe("searchMessages", () => {
+    it.todo("returns ranked results for matching term");
+    it.todo("returns empty for no match");
+    it.todo("respects companyId scope");
+  });
+
+  describe("toggleBookmark", () => {
+    it.todo("creates bookmark when not exists");
+    it.todo("removes bookmark when exists");
+  });
+
+  describe("branchConversation", () => {
+    it.todo("creates child conversation with copied messages");
+    it.todo("throws not found for invalid message id");
+  });
+
+  describe("exportConversation", () => {
+    it.todo("exports as markdown with agent names");
+    it.todo("exports as JSON with all messages");
+  });
 });