Track per-employee chat read state and surface real unread counts

Adds chat_read_state migration (employee_id + space_id, last read
message + timestamp) wired through ChatService.markSpaceRead, IPC
markChatSpaceRead, and an effect in ChatPage that flushes the active
space whenever the latest message id changes.

Shell.computeBadges now derives the Messages badge from
(message.createdAt > read_state.last_read_at) minus messages the viewer
sent, so the sidebar shows true unread instead of total throughput.

AgentCompany-New/src/renderer/src/pages/ChatPage.tsx

@@ -1,4 +1,4 @@
-import { useMemo, useRef, useState, type FormEvent } from "react";
+import { useEffect, useMemo, useRef, useState, type FormEvent } from "react";
 import { Field } from "../shared/ui";
 import { Dialog } from "../shared/Dialog";
 import { ChatSidebar } from "./chat/ChatSidebar";
@@ -46,6 +46,22 @@ export function ChatPage({ snapshot, actions }: PageProps) {
     ? selectedSpaceId
     : fallbackSpaceId;
   const activeSpace = spaces.find((space) => space.id === activeSpaceId) ?? null;
+  const latestActiveMessageId = useMemo(() => {
+    if (!activeSpace) return null;
+    const inSpace = messagesAll.filter((message) => message.spaceId === activeSpace.id);
+    if (inSpace.length === 0) return null;
+    return inSpace[inSpace.length - 1].id;
+  }, [messagesAll, activeSpace]);
+
+  useEffect(() => {
+    if (!activeSpace || !latestActiveMessageId) return;
+    void actions.run(() => window.agentCompany.markChatSpaceRead({
+      orgId,
+      employeeId: employee.id,
+      spaceId: activeSpace.id,
+    }));
+  }, [activeSpace, latestActiveMessageId, orgId, employee.id, actions]);
+
   const messagesInSpace = useMemo(
     () => (activeSpace ? messagesAll.filter((m) => m.spaceId === activeSpace.id) : []),
     [messagesAll, activeSpace],

AgentCompany-New/src/renderer/src/shared/Shell.tsx

@@ -136,10 +136,29 @@ function renderBadge(value: number | undefined): ReactNode {
 }
 
 function computeBadges(snapshot: AppSnapshot, orgId: string): Partial<Record<RouteId, number>> {
+  const employee = snapshot.employees.find((item) => item.orgId === orgId);
   const tasks = snapshot.tasks.filter((item) => item.orgId === orgId);
   const approvals = snapshot.approvals.filter((item) => item.orgId === orgId);
   return {
     work: tasks.filter((task) => task.status !== "done").length,
+    chat: employee ? countUnreadMessages(snapshot, orgId, employee.id) : 0,
     approvals: approvals.filter((approval) => approval.state === "pending").length,
   };
 }
+
+function countUnreadMessages(snapshot: AppSnapshot, orgId: string, employeeId: string): number {
+  const readByspace = new Map<string, string>();
+  for (const state of snapshot.chatReadStates) {
+    if (state.orgId !== orgId || state.employeeId !== employeeId) continue;
+    readByspace.set(state.spaceId, state.lastReadAt);
+  }
+  let unread = 0;
+  for (const message of snapshot.chatMessages) {
+    if (message.orgId !== orgId) continue;
+    if (message.senderType === "employee" && message.senderId === employeeId) continue;
+    const lastRead = readByspace.get(message.spaceId);
+    if (lastRead && message.createdAt <= lastRead) continue;
+    unread += 1;
+  }
+  return unread;
+}