feat: add chat components from jarvis frontend

- Migrated Chat.tsx with message handling and UI structure
- Migrated ChatInput.tsx with character limits and keyboard shortcuts
- Migrated MessageList.tsx with thinking/reasoning display
- Migrated ConversationSidebar.tsx (simplified placeholder)
- Migrated BackendStatusBanner.tsx (simplified placeholder)
- Created components/chat/index.ts barrel export
- Created app/chat/page.tsx placeholder route

These components are adapted from jarvis-fe but not yet fully functional:
- API calls placeholder (need to wire up /api/brain/query)
- Auth hooks stubbed (need useAuth implementation)
- Project/conversation hooks stubbed (need implementation)
- Imports changed from @jarvis/* to @mosaic/*

Next steps:
- Implement missing hooks (useAuth, useProjects, useConversations, useApi)
- Wire up backend API endpoints
- Add proper TypeScript types
- Implement full conversation management

apps/web/src/app/chat/page.tsx

@@ -0,0 +1,99 @@
+"use client";
+
+import { useRef, useState } from "react";
+import { Chat, type ChatRef, ConversationSidebar, type ConversationSidebarRef } from "@/components/chat";
+
+/**
+ * Chat Page
+ * 
+ * Placeholder route for the chat interface migrated from jarvis-fe.
+ * 
+ * TODO:
+ * - Integrate with authentication
+ * - Connect to brain API endpoints (/api/brain/query)
+ * - Implement conversation persistence
+ * - Add project/workspace integration
+ * - Wire up actual hooks (useAuth, useProjects, useConversations, useApi)
+ */
+export default function ChatPage() {
+  const chatRef = useRef<ChatRef>(null);
+  const sidebarRef = useRef<ConversationSidebarRef>(null);
+  const [sidebarOpen, setSidebarOpen] = useState(false);
+  const [currentConversationId, setCurrentConversationId] = useState<string | null>(null);
+
+  const handleConversationChange = (conversationId: string | null) => {
+    setCurrentConversationId(conversationId);
+    // TODO: Update sidebar when conversation changes
+  };
+
+  const handleSelectConversation = (conversationId: string | null) => {
+    // TODO: Load conversation from backend
+    console.log("Select conversation:", conversationId);
+    setCurrentConversationId(conversationId);
+  };
+
+  const handleNewConversation = (projectId?: string | null) => {
+    chatRef.current?.startNewConversation(projectId);
+    setCurrentConversationId(null);
+  };
+
+  return (
+    <div className="flex h-screen overflow-hidden" style={{ backgroundColor: "rgb(var(--color-background))" }}>
+      {/* Conversation Sidebar */}
+      <ConversationSidebar
+        ref={sidebarRef}
+        isOpen={sidebarOpen}
+        onClose={() => setSidebarOpen(!sidebarOpen)}
+        currentConversationId={currentConversationId}
+        onSelectConversation={handleSelectConversation}
+        onNewConversation={handleNewConversation}
+      />
+
+      {/* Main Chat Area */}
+      <div className="flex flex-1 flex-col overflow-hidden">
+        {/* Header */}
+        <header
+          className="border-b px-4 py-3 flex items-center gap-3"
+          style={{
+            backgroundColor: "rgb(var(--surface-0))",
+            borderColor: "rgb(var(--border-default))",
+          }}
+        >
+          {/* Toggle Sidebar Button */}
+          <button
+            onClick={() => setSidebarOpen(!sidebarOpen)}
+            className="p-2 rounded-lg transition-colors hover:bg-[rgb(var(--surface-1))]"
+            aria-label="Toggle sidebar"
+            title="Toggle conversation history"
+          >
+            <svg
+              className="h-5 w-5"
+              style={{ color: "rgb(var(--text-muted))" }}
+              fill="none"
+              viewBox="0 0 24 24"
+              stroke="currentColor"
+              strokeWidth={1.5}
+            >
+              <path d="M3.75 6.75h16.5M3.75 12h16.5m-16.5 5.25h16.5" />
+            </svg>
+          </button>
+
+          <div className="flex-1">
+            <h1 className="text-lg font-semibold" style={{ color: "rgb(var(--text-primary))" }}>
+              AI Chat
+            </h1>
+            <p className="text-xs" style={{ color: "rgb(var(--text-muted))" }}>
+              Migrated from Jarvis - Connect to brain API for full functionality
+            </p>
+          </div>
+        </header>
+
+        {/* Chat Component */}
+        <Chat
+          ref={chatRef}
+          onConversationChange={handleConversationChange}
+        />
+      </div>
+    </div>
+  );
+}

apps/web/src/components/chat/BackendStatusBanner.tsx

@@ -0,0 +1,98 @@
+"use client";
+
+import { useState, useEffect } from "react";
+
+/**
+ * Banner that displays when the backend is unavailable.
+ * Shows error message, countdown to next retry, and manual retry button.
+ * 
+ * TODO: Integrate with actual backend status checking hook
+ */
+export function BackendStatusBanner() {
+  const [isAvailable, setIsAvailable] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [retryIn, setRetryIn] = useState(0);
+
+  // TODO: Replace with actual useBackendStatus hook
+  // const { isAvailable, error, retryIn, manualRetry } = useBackendStatus();
+
+  const manualRetry = () => {
+    // TODO: Implement manual retry logic
+    console.log("Manual retry triggered");
+  };
+
+  const handleSignOut = async () => {
+    try {
+      // TODO: Implement signOut
+      // await signOut();
+    } catch (error) {
+      console.warn("Sign-out failed during backend unavailability:", error);
+    }
+    window.location.href = "/login";
+  };
+
+  // Don't render if backend is available
+  if (isAvailable) {
+    return null;
+  }
+
+  return (
+    <div
+      className="flex items-center justify-between gap-4 px-4 py-2 text-sm"
+      style={{
+        backgroundColor: "#fef3c7", // amber-100
+        borderBottom: "1px solid #fcd34d", // amber-300
+        color: "#92400e", // amber-800
+      }}
+      role="alert"
+      aria-live="polite"
+    >
+      <div className="flex items-center gap-2">
+        <svg
+          xmlns="http://www.w3.org/2000/svg"
+          className="h-5 w-5 flex-shrink-0"
+          viewBox="0 0 20 20"
+          fill="currentColor"
+          aria-hidden="true"
+        >
+          <path
+            fillRule="evenodd"
+            d="M8.257 3.099c.765-1.36 2.722-1.36 3.486 0l5.58 9.92c.75 1.334-.213 2.98-1.742 2.98H4.42c-1.53 0-2.493-1.646-1.743-2.98l5.58-9.92zM11 13a1 1 0 11-2 0 1 1 0 012 0zm-1-8a1 1 0 00-1 1v3a1 1 0 002 0V6a1 1 0 00-1-1z"
+            clipRule="evenodd"
+          />
+        </svg>
+        <span>
+          {error || "Backend temporarily unavailable."}
+          {retryIn > 0 && (
+            <span className="ml-1">
+              Retrying in {retryIn}s...
+            </span>
+          )}
+        </span>
+      </div>
+      <div className="flex items-center gap-2">
+        <button
+          onClick={manualRetry}
+          className="rounded px-3 py-1 text-xs font-medium transition-colors hover:opacity-80"
+          style={{
+            backgroundColor: "#fcd34d", // amber-300
+            color: "#92400e", // amber-800
+          }}
+        >
+          Retry Now
+        </button>
+        <button
+          onClick={handleSignOut}
+          className="rounded px-3 py-1 text-xs font-medium transition-colors hover:opacity-80"
+          style={{
+            backgroundColor: "transparent",
+            color: "#92400e", // amber-800
+            border: "1px solid #fcd34d", // amber-300
+          }}
+        >
+          Sign in again
+        </button>
+      </div>
+    </div>
+  );
+}

apps/web/src/components/chat/Chat.tsx

@@ -0,0 +1,378 @@
+"use client";
+
+import { useCallback, useEffect, useRef, useState, useMemo, forwardRef, useImperativeHandle } from "react";
+// TODO: These hooks will need to be created or adapted
+// import { useAuth } from "@/lib/hooks/useAuth";
+// import { useProjects } from "@/lib/hooks/useProjects";
+// import { useConversations } from "@/lib/hooks/useConversations";
+// import { useApi } from "@/lib/hooks/useApi";
+import { MessageList } from "./MessageList";
+import { ChatInput } from "./ChatInput";
+// TODO: Import types need to be created
+// import type { ConversationDetail } from "@/lib/hooks/useConversations";
+// import { handleSessionExpired, isSessionExpiring } from "@/lib/api";
+// import type { LLMModel, DefaultModel } from "@/lib/api";
+
+// Placeholder types until the actual types are created
+type ConversationDetail = any;
+type LLMModel = any;
+type DefaultModel = any;
+
+export interface Message {
+  id: string;
+  role: "user" | "assistant" | "system";
+  content: string;
+  thinking?: string;  // Chain of thought reasoning from thinking models
+  createdAt: string;
+  model?: string;  // LLM model used for this response
+  provider?: string;  // LLM provider (ollama, claude, etc.)
+  // Token usage info
+  promptTokens?: number;
+  completionTokens?: number;
+  totalTokens?: number;
+}
+
+const API_URL = process.env.NEXT_PUBLIC_API_URL || "http://localhost:8000";
+
+// Friendly waiting messages (shown after a few seconds of loading)
+const WAITING_QUIPS = [
+  "The AI is warming up... give it a moment.",
+  "Loading the neural pathways...",
+  "Waking up the LLM. It's not a morning model.",
+  "Brewing some thoughts...",
+  "The AI is stretching its parameters...",
+  "Summoning intelligence from the void...",
+  "Teaching electrons to think...",
+  "Consulting the silicon oracle...",
+  "The hamsters are spinning up the GPU...",
+  "Defragmenting the neural networks...",
+];
+
+// Error messages for actual timeouts
+const TIMEOUT_QUIPS = [
+  "The AI got lost in thought. Literally. Try again?",
+  "That took too long, even by AI standards. Give it another go?",
+  "The model wandered off. Let's try to find it again.",
+  "Response timed out. The AI may have fallen asleep. Retry?",
+  "The LLM took an unexpected vacation. One more attempt?",
+];
+
+// Error messages for connection failures
+const CONNECTION_QUIPS = [
+  "I seem to have misplaced the server. Check your connection?",
+  "The server and I are having communication issues. It's not you, it's us.",
+  "Connection lost. Either the internet is down, or the server is playing hide and seek.",
+  "Unable to reach the mothership. The tubes appear to be clogged.",
+  "The server isn't responding. Perhaps it's giving us the silent treatment.",
+];
+
+const getRandomQuip = (quips: string[]) => quips[Math.floor(Math.random() * quips.length)];
+
+const WELCOME_MESSAGE: Message = {
+  id: "welcome",
+  role: "assistant",
+  content: "Hello. I'm your AI assistant. How can I help you today?",
+  createdAt: new Date().toISOString(),
+};
+
+export interface ChatRef {
+  loadConversation: (conversation: ConversationDetail) => void;
+  startNewConversation: (projectId?: string | null) => void;
+  getCurrentConversationId: () => string | null;
+}
+
+export interface NewConversationData {
+  id: string;
+  title: string | null;
+  project_id: string | null;
+  created_at: string;
+  updated_at: string;
+}
+
+interface ChatProps {
+  onConversationChange?: (conversationId: string | null, conversationData?: NewConversationData) => void;
+  onProjectChange?: () => void;
+  initialProjectId?: string | null;
+  onInitialProjectHandled?: () => void;
+}
+
+export const Chat = forwardRef<ChatRef, ChatProps>(function Chat({
+  onConversationChange,
+  onProjectChange: _onProjectChange,
+  initialProjectId,
+  onInitialProjectHandled,
+}, ref) {
+  void _onProjectChange; // Kept for potential future use
+  
+  // TODO: Replace with actual hooks once they're created
+  const accessToken = null;
+  const isLoading = false;
+  const authLoading = false;
+  const authError = null;
+  const projects: any[] = [];
+  // const { accessToken, isLoading: authLoading, error: authError } = useAuth();
+  // const { projects } = useProjects();
+  // const { updateConversationProject } = useConversations();
+  // const api = useApi();
+  
+  const [messages, setMessages] = useState<Message[]>([WELCOME_MESSAGE]);
+  const [isChatLoading, setIsChatLoading] = useState(false);
+  const [loadingQuip, setLoadingQuip] = useState<string | null>(null);
+  const [error, setError] = useState<string | null>(null);
+  const [conversationId, setConversationId] = useState<string | null>(null);
+  const [conversationTitle, setConversationTitle] = useState<string | null>(null);
+  const [conversationProjectId, setConversationProjectId] = useState<string | null>(null);
+  const [pendingProjectId, setPendingProjectId] = useState<string | null>(null);
+  const [showProjectMenu, setShowProjectMenu] = useState(false);
+  const [showModelMenu, setShowModelMenu] = useState(false);
+  const [showFooterProjectMenu, setShowFooterProjectMenu] = useState(false);
+  const [showFooterModelMenu, setShowFooterModelMenu] = useState(false);
+  const [isMovingProject, setIsMovingProject] = useState(false);
+  const [availableModels, setAvailableModels] = useState<LLMModel[]>([]);
+  const [defaultModel, setDefaultModel] = useState<DefaultModel | null>(null);
+  const [selectedModel, setSelectedModel] = useState<LLMModel | null>(null);
+  const [modelLoadError, setModelLoadError] = useState<string | null>(null);
+  const [isLoadingModels, setIsLoadingModels] = useState(false);
+  const [useReasoning, setUseReasoning] = useState(false);  // Toggle for reasoning/thinking mode
+  const messagesEndRef = useRef<HTMLDivElement>(null);
+  const inputRef = useRef<HTMLTextAreaElement>(null);
+  const projectMenuRef = useRef<HTMLDivElement>(null);
+  const modelMenuRef = useRef<HTMLDivElement>(null);
+  const footerProjectMenuRef = useRef<HTMLDivElement>(null);
+  const footerModelMenuRef = useRef<HTMLDivElement>(null);
+  // Track conversation ID in ref to prevent stale closure issues
+  const conversationIdRef = useRef<string | null>(conversationId);
+
+  // Expose methods to parent via ref
+  useImperativeHandle(ref, () => ({
+    loadConversation: (conversation: ConversationDetail) => {
+      // TODO: Implement once ConversationDetail type is available
+      console.log("loadConversation called with:", conversation);
+    },
+    startNewConversation: (projectId?: string | null) => {
+      setConversationId(null);
+      setConversationTitle(null);
+      setConversationProjectId(null);
+      setMessages([WELCOME_MESSAGE]);
+      setError(null);
+      setPendingProjectId(projectId || null);
+      setShowProjectMenu(false);
+      onConversationChange?.(null);
+    },
+    getCurrentConversationId: () => conversationId,
+  }));
+
+  const scrollToBottom = useCallback(() => {
+    messagesEndRef.current?.scrollIntoView({ behavior: "smooth" });
+  }, []);
+
+  useEffect(() => {
+    scrollToBottom();
+  }, [messages, scrollToBottom]);
+
+  // Keep conversationIdRef in sync with state to prevent stale closures
+  useEffect(() => {
+    conversationIdRef.current = conversationId;
+  }, [conversationId]);
+
+  // Handle auth errors
+  useEffect(() => {
+    if (authError === "RefreshAccessTokenError") {
+      setError("Your session has expired. Please sign in again.");
+    }
+  }, [authError]);
+
+  // Global keyboard shortcut: Ctrl+/ to focus input
+  useEffect(() => {
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if ((e.ctrlKey || e.metaKey) && e.key === "/") {
+        e.preventDefault();
+        inputRef.current?.focus();
+      }
+    };
+    document.addEventListener("keydown", handleKeyDown);
+    return () => document.removeEventListener("keydown", handleKeyDown);
+  }, []);
+
+  // TODO: Implement click outside handlers for menus
+
+  const sendMessage = useCallback(
+    async (content: string) => {
+      if (!content.trim() || isChatLoading) {
+        return;
+      }
+
+      // Add user message immediately
+      const userMessage: Message = {
+        id: `user-${Date.now()}`,
+        role: "user",
+        content: content.trim(),
+        createdAt: new Date().toISOString(),
+      };
+
+      setMessages((prev) => [...prev, userMessage]);
+      setIsChatLoading(true);
+      setLoadingQuip(null);
+      setError(null);
+
+      // Show a witty loading message after 3 seconds
+      const quipTimerId = setTimeout(() => {
+        setLoadingQuip(getRandomQuip(WAITING_QUIPS));
+      }, 3000);
+
+      // Change quip every 5 seconds if still waiting
+      const quipIntervalId = setInterval(() => {
+        setLoadingQuip(getRandomQuip(WAITING_QUIPS));
+      }, 5000);
+
+      try {
+        // TODO: Implement actual API call to /api/brain/query
+        const requestBody: {
+          message: string;
+          conversation_id: string | null;
+          project_id?: string;
+          provider_instance_id?: string;
+          provider?: string;
+          model?: string;
+          use_reasoning?: boolean;
+        } = {
+          message: content.trim(),
+          conversation_id: conversationId,
+        };
+
+        // Placeholder response for now
+        await new Promise(resolve => setTimeout(resolve, 1000));
+        
+        const assistantMessage: Message = {
+          id: `assistant-${Date.now()}`,
+          role: "assistant",
+          content: "This is a placeholder response. The chat API integration is not yet complete.",
+          createdAt: new Date().toISOString(),
+        };
+
+        setMessages((prev) => [...prev, assistantMessage]);
+
+        // Clear quip timers on success
+        clearTimeout(quipTimerId);
+        clearInterval(quipIntervalId);
+        setLoadingQuip(null);
+      } catch (err) {
+        // Clear quip timers on error
+        clearTimeout(quipTimerId);
+        clearInterval(quipIntervalId);
+        setLoadingQuip(null);
+
+        console.error("Failed to send message:", err);
+        const errorMsg = err instanceof Error ? err.message : "Failed to send message";
+        setError(errorMsg);
+
+        const errorMessage: Message = {
+          id: `error-${Date.now()}`,
+          role: "assistant",
+          content: errorMsg,
+          createdAt: new Date().toISOString(),
+        };
+        setMessages((prev) => [...prev, errorMessage]);
+      } finally {
+        setIsChatLoading(false);
+      }
+    },
+    [conversationId, isChatLoading]
+  );
+
+  const dismissError = useCallback(() => {
+    setError(null);
+  }, []);
+
+  // Show loading state while auth is loading
+  if (authLoading) {
+    return (
+      <div className="flex flex-1 items-center justify-center" style={{ backgroundColor: "rgb(var(--color-background))" }}>
+        <div className="flex items-center gap-3">
+          <div className="h-5 w-5 animate-spin rounded-full border-2 border-t-transparent" style={{ borderColor: "rgb(var(--accent-primary))", borderTopColor: "transparent" }} />
+          <span style={{ color: "rgb(var(--text-secondary))" }}>Loading...</span>
+        </div>
+      </div>
+    );
+  }
+
+  return (
+    <div className="flex flex-1 flex-col" style={{ backgroundColor: "rgb(var(--color-background))" }}>
+      {/* Messages Area */}
+      <div className="flex-1 overflow-y-auto">
+        <div className="mx-auto max-w-4xl px-4 py-6 lg:px-8">
+          <MessageList messages={messages} isLoading={isChatLoading} loadingQuip={loadingQuip} />
+          <div ref={messagesEndRef} />
+        </div>
+      </div>
+
+      {/* Error Alert */}
+      {error && (
+        <div className="mx-4 mb-2 lg:mx-auto lg:max-w-4xl lg:px-8">
+          <div
+            className="flex items-center justify-between rounded-lg border px-4 py-3"
+            style={{
+              backgroundColor: "rgb(var(--semantic-error-light))",
+              borderColor: "rgb(var(--semantic-error) / 0.3)",
+            }}
+            role="alert"
+          >
+            <div className="flex items-center gap-3">
+              <svg
+                className="h-4 w-4 flex-shrink-0"
+                style={{ color: "rgb(var(--semantic-error))" }}
+                fill="none"
+                viewBox="0 0 24 24"
+                stroke="currentColor"
+                strokeWidth={2}
+              >
+                <circle cx="12" cy="12" r="10" />
+                <line x1="12" y1="8" x2="12" y2="12" />
+                <line x1="12" y1="16" x2="12.01" y2="16" />
+              </svg>
+              <span
+                className="text-sm"
+                style={{ color: "rgb(var(--semantic-error-dark))" }}
+              >
+                {error}
+              </span>
+            </div>
+            <button
+              onClick={dismissError}
+              className="rounded p-1 transition-colors hover:bg-black/5"
+              aria-label="Dismiss error"
+            >
+              <svg
+                className="h-4 w-4"
+                style={{ color: "rgb(var(--semantic-error))" }}
+                fill="none"
+                viewBox="0 0 24 24"
+                stroke="currentColor"
+                strokeWidth={2}
+              >
+                <path d="M18 6 6 18M6 6l12 12" />
+              </svg>
+            </button>
+          </div>
+        </div>
+      )}
+
+      {/* Input Area */}
+      <div
+        className="sticky bottom-0 border-t"
+        style={{
+          backgroundColor: "rgb(var(--surface-0))",
+          borderColor: "rgb(var(--border-default))",
+        }}
+      >
+        <div className="mx-auto max-w-4xl px-4 py-4 lg:px-8">
+          <ChatInput
+            onSend={sendMessage}
+            disabled={isChatLoading || !accessToken}
+            inputRef={inputRef}
+          />
+        </div>
+      </div>
+    </div>
+  );
+});

apps/web/src/components/chat/ChatInput.tsx

@@ -0,0 +1,189 @@
+"use client";
+
+import { useCallback, useState, useEffect, KeyboardEvent, RefObject } from "react";
+
+interface ChatInputProps {
+  onSend: (message: string) => void;
+  disabled?: boolean;
+  inputRef?: RefObject<HTMLTextAreaElement | null>;
+}
+
+export function ChatInput({ onSend, disabled, inputRef }: ChatInputProps) {
+  const [message, setMessage] = useState("");
+  const [version, setVersion] = useState<string | null>(null);
+
+  // Fetch version from static version.json (generated at build time)
+  useEffect(() => {
+    fetch("/version.json")
+      .then((res) => res.json())
+      .then((data) => {
+        if (data.version) {
+          // Format as "version+commit" for full build identification
+          const fullVersion = data.commit
+            ? `${data.version}+${data.commit}`
+            : data.version;
+          setVersion(fullVersion);
+        }
+      })
+      .catch(() => {
+        // Silently fail - version display is non-critical
+      });
+  }, []);
+
+  const handleSubmit = useCallback(() => {
+    if (message.trim() && !disabled) {
+      onSend(message);
+      setMessage("");
+    }
+  }, [message, onSend, disabled]);
+
+  const handleKeyDown = useCallback(
+    (e: KeyboardEvent<HTMLTextAreaElement>) => {
+      // Enter to send (without Shift)
+      if (e.key === "Enter" && !e.shiftKey) {
+        e.preventDefault();
+        handleSubmit();
+      }
+      // Ctrl/Cmd + Enter to send (alternative)
+      if (e.key === "Enter" && (e.ctrlKey || e.metaKey)) {
+        e.preventDefault();
+        handleSubmit();
+      }
+    },
+    [handleSubmit]
+  );
+
+  const characterCount = message.length;
+  const maxCharacters = 4000;
+  const isNearLimit = characterCount > maxCharacters * 0.9;
+  const isOverLimit = characterCount > maxCharacters;
+
+  return (
+    <div className="space-y-3">
+      {/* Input Container */}
+      <div
+        className="relative rounded-lg border transition-all duration-150"
+        style={{
+          backgroundColor: "rgb(var(--surface-0))",
+          borderColor: disabled
+            ? "rgb(var(--border-default))"
+            : "rgb(var(--border-strong))",
+        }}
+      >
+        <textarea
+          ref={inputRef}
+          value={message}
+          onChange={(e) => setMessage(e.target.value)}
+          onKeyDown={handleKeyDown}
+          placeholder="Type a message..."
+          disabled={disabled}
+          rows={1}
+          className="block w-full resize-none bg-transparent px-4 py-3 pr-24 text-sm outline-none placeholder:text-[rgb(var(--text-muted))] disabled:opacity-50"
+          style={{
+            color: "rgb(var(--text-primary))",
+            minHeight: "48px",
+            maxHeight: "200px",
+          }}
+          onInput={(e) => {
+            const target = e.target as HTMLTextAreaElement;
+            target.style.height = "auto";
+            target.style.height = Math.min(target.scrollHeight, 200) + "px";
+          }}
+          aria-label="Message input"
+          aria-describedby="input-help"
+        />
+
+        {/* Send Button */}
+        <div className="absolute bottom-2 right-2 flex items-center gap-2">
+          <button
+            onClick={handleSubmit}
+            disabled={disabled || !message.trim() || isOverLimit}
+            className="btn-primary btn-sm rounded-md"
+            style={{
+              opacity: disabled || !message.trim() || isOverLimit ? 0.5 : 1,
+            }}
+            aria-label="Send message"
+          >
+            <svg
+              className="h-4 w-4"
+              fill="none"
+              viewBox="0 0 24 24"
+              stroke="currentColor"
+              strokeWidth={2}
+            >
+              <path d="M5 12h14M12 5l7 7-7 7" />
+            </svg>
+            <span className="hidden sm:inline">Send</span>
+          </button>
+        </div>
+      </div>
+
+      {/* Footer: Keyboard shortcuts + character count */}
+      <div
+        className="flex items-center justify-between text-xs"
+        style={{ color: "rgb(var(--text-muted))" }}
+        id="input-help"
+      >
+        {/* Keyboard Shortcuts */}
+        <div className="hidden items-center gap-4 sm:flex">
+          <div className="flex items-center gap-1.5">
+            <span className="kbd">Enter</span>
+            <span>to send</span>
+          </div>
+          <div className="flex items-center gap-1.5">
+            <span className="kbd">Shift</span>
+            <span>+</span>
+            <span className="kbd">Enter</span>
+            <span>for new line</span>
+          </div>
+        </div>
+
+        {/* Mobile hint */}
+        <div className="sm:hidden">
+          Tap send or press Enter
+        </div>
+
+        {/* Character Count */}
+        <div
+          className="flex items-center gap-2"
+          style={{
+            color: isOverLimit
+              ? "rgb(var(--semantic-error))"
+              : isNearLimit
+              ? "rgb(var(--semantic-warning))"
+              : "rgb(var(--text-muted))",
+          }}
+        >
+          {characterCount > 0 && (
+            <>
+              <span>
+                {characterCount.toLocaleString()}/{maxCharacters.toLocaleString()}
+              </span>
+              {isOverLimit && (
+                <svg className="h-3.5 w-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                  <circle cx="12" cy="12" r="10" />
+                  <line x1="12" y1="8" x2="12" y2="12" />
+                  <line x1="12" y1="16" x2="12.01" y2="16" />
+                </svg>
+              )}
+            </>
+          )}
+        </div>
+      </div>
+
+      {/* AI Disclaimer & Version */}
+      <div
+        className="flex items-center justify-center gap-2 text-xs"
+        style={{ color: "rgb(var(--text-muted))" }}
+      >
+        <span>AI may produce inaccurate information. Verify important details.</span>
+        {version && (
+          <>
+            <span>·</span>
+            <span>v{version}</span>
+          </>
+        )}
+      </div>
+    </div>
+  );
+}

apps/web/src/components/chat/ConversationSidebar.tsx

@@ -0,0 +1,245 @@
+"use client";
+
+import { useState, forwardRef, useImperativeHandle } from "react";
+// import Link from "next/link";
+// TODO: Import hooks when they're created
+// import { useConversations, ConversationSummary } from "@/lib/hooks/useConversations";
+// import { useProjects } from "@/lib/hooks/useProjects";
+// import type { IsolationMode } from "@/lib/api";
+
+// Placeholder types
+type ConversationSummary = {
+  id: string;
+  title: string | null;
+  project_id: string | null;
+  updated_at: string;
+  message_count: number;
+};
+
+export interface ConversationSidebarRef {
+  refresh: () => void;
+  addConversation: (conversation: ConversationSummary) => void;
+}
+
+interface ConversationSidebarProps {
+  isOpen: boolean;
+  onClose: () => void;
+  currentConversationId: string | null;
+  onSelectConversation: (conversationId: string | null) => void;
+  onNewConversation: (projectId?: string | null) => void;
+}
+
+export const ConversationSidebar = forwardRef<ConversationSidebarRef, ConversationSidebarProps>(function ConversationSidebar({
+  isOpen,
+  onClose,
+  currentConversationId,
+  onSelectConversation,
+  onNewConversation,
+}, ref) {
+  const [searchQuery, setSearchQuery] = useState("");
+  
+  // Placeholder data
+  const conversations: ConversationSummary[] = [];
+  const projects: any[] = [];
+
+  // Expose methods to parent via ref
+  useImperativeHandle(ref, () => ({
+    refresh: () => {
+      // TODO: Implement refresh logic
+      console.log("Refresh called");
+    },
+    addConversation: (conversation: ConversationSummary) => {
+      // TODO: Implement addConversation logic
+      console.log("Add conversation called:", conversation);
+    },
+  }));
+
+  const filteredConversations = conversations.filter((conv) => {
+    if (!searchQuery.trim()) return true;
+    const title = conv.title || "Untitled conversation";
+    return title.toLowerCase().includes(searchQuery.toLowerCase());
+  });
+
+  const formatRelativeTime = (dateString: string) => {
+    const date = new Date(dateString);
+    const now = new Date();
+    const diffMs = now.getTime() - date.getTime();
+    const diffMins = Math.floor(diffMs / 60000);
+    const diffHours = Math.floor(diffMs / 3600000);
+    const diffDays = Math.floor(diffMs / 86400000);
+
+    if (diffMins < 1) return "Just now";
+    if (diffMins < 60) return `${diffMins}m ago`;
+    if (diffHours < 24) return `${diffHours}h ago`;
+    if (diffDays < 7) return `${diffDays}d ago`;
+    return date.toLocaleDateString(undefined, { month: "short", day: "numeric" });
+  };
+
+  const truncateTitle = (title: string | null, maxLength = 32) => {
+    const displayTitle = title || "Untitled conversation";
+    if (displayTitle.length <= maxLength) return displayTitle;
+    return displayTitle.substring(0, maxLength - 1) + "…";
+  };
+
+  return (
+    <>
+      {/* Mobile overlay */}
+      {isOpen && (
+        <div
+          className="fixed inset-0 z-40 md:hidden animate-fade-in"
+          style={{ backgroundColor: "rgb(0 0 0 / 0.6)" }}
+          onClick={onClose}
+          aria-hidden="true"
+        />
+      )}
+
+      {/* Sidebar */}
+      <aside
+        className={`
+          fixed left-0 top-0 z-50 h-screen transform border-r transition-all duration-200 ease-out flex flex-col
+          md:sticky md:top-0 md:z-auto md:h-screen md:transform-none md:transition-[width]
+          ${isOpen ? "translate-x-0 w-72" : "-translate-x-full md:translate-x-0 md:w-16"}
+        `}
+        style={{
+          backgroundColor: "rgb(var(--surface-0))",
+          borderColor: "rgb(var(--border-default))",
+        }}
+        aria-label="Conversation history"
+      >
+        {/* Collapsed view - TODO: Implement */}
+        {!isOpen && (
+          <div className="hidden md:flex flex-col items-center py-3 h-full">
+            <button
+              onClick={() => onNewConversation()}
+              className="p-3 rounded-lg transition-colors"
+              title="New Conversation"
+            >
+              <svg className="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                <path d="M12 4v16m8-8H4" />
+              </svg>
+            </button>
+          </div>
+        )}
+
+        {/* Full sidebar content */}
+        {isOpen && (
+          <>
+            {/* Header */}
+            <div
+              className="flex items-center justify-between border-b px-4 py-3"
+              style={{ borderColor: "rgb(var(--border-default))" }}
+            >
+              <div className="flex items-center gap-2">
+                <svg
+                  className="h-5 w-5"
+                  style={{ color: "rgb(var(--text-muted))" }}
+                  fill="none"
+                  viewBox="0 0 24 24"
+                  stroke="currentColor"
+                  strokeWidth={1.5}
+                >
+                  <path d="M8 12h.01M12 12h.01M16 12h.01M21 12c0 4.418-4.03 8-9 8a9.863 9.863 0 01-4.255-.949L3 20l1.395-3.72C3.512 15.042 3 13.574 3 12c0-4.418 4.03-8 9-8s9 3.582 9 8z" />
+                </svg>
+                <span className="text-sm font-semibold" style={{ color: "rgb(var(--text-primary))" }}>
+                  Conversations
+                </span>
+              </div>
+
+              <button onClick={onClose} className="btn-ghost rounded-md p-1.5" aria-label="Close sidebar">
+                <svg className="h-5 w-5" style={{ color: "rgb(var(--text-muted))" }} fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={1.5}>
+                  <path d="M6 18L18 6M6 6l12 12" />
+                </svg>
+              </button>
+            </div>
+
+            {/* New Chat Button */}
+            <div className="px-3 pt-3">
+              <button
+                onClick={() => onNewConversation()}
+                className="w-full flex items-center justify-center gap-2 rounded-lg border border-dashed py-2.5 text-sm font-medium transition-all duration-150 hover:border-solid"
+                style={{
+                  borderColor: "rgb(var(--border-strong))",
+                  color: "rgb(var(--text-secondary))",
+                }}
+              >
+                <svg className="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                  <path d="M12 4v16m8-8H4" />
+                </svg>
+                <span>New Conversation</span>
+              </button>
+            </div>
+
+            {/* Search */}
+            <div className="px-3 pt-3">
+              <div className="relative">
+                <svg
+                  className="absolute left-3 top-1/2 h-4 w-4 -translate-y-1/2"
+                  style={{ color: "rgb(var(--text-muted))" }}
+                  fill="none"
+                  viewBox="0 0 24 24"
+                  stroke="currentColor"
+                  strokeWidth={2}
+                >
+                  <circle cx="11" cy="11" r="8" />
+                  <path d="M21 21l-4.35-4.35" />
+                </svg>
+                <input
+                  type="text"
+                  placeholder="Search conversations..."
+                  value={searchQuery}
+                  onChange={(e) => setSearchQuery(e.target.value)}
+                  className="input pl-9 pr-10 py-2 text-sm"
+                  style={{ backgroundColor: "rgb(var(--surface-1))" }}
+                />
+              </div>
+            </div>
+
+            {/* Conversations List */}
+            <div className="flex-1 overflow-y-auto px-3 pt-3 pb-3 space-y-1">
+              {filteredConversations.length === 0 ? (
+                <div className="text-center py-8" style={{ color: "rgb(var(--text-muted))" }}>
+                  <p className="text-sm">No conversations yet</p>
+                  <p className="text-xs mt-1">Start a new chat to begin</p>
+                </div>
+              ) : (
+                filteredConversations.map((conv) => (
+                  <button
+                    key={conv.id}
+                    onClick={() => onSelectConversation(conv.id)}
+                    className={`w-full text-left px-3 py-2 rounded-lg transition-colors ${
+                      conv.id === currentConversationId
+                        ? "bg-[rgb(var(--accent-primary-light))]"
+                        : "hover:bg-[rgb(var(--surface-2))]"
+                    }`}
+                  >
+                    <p
+                      className="text-sm font-medium truncate"
+                      style={{
+                        color: conv.id === currentConversationId
+                          ? "rgb(var(--accent-primary))"
+                          : "rgb(var(--text-primary))",
+                      }}
+                    >
+                      {truncateTitle(conv.title)}
+                    </p>
+                    <div className="flex items-center gap-2 mt-0.5" style={{ color: "rgb(var(--text-muted))" }}>
+                      <span className="text-xs">{formatRelativeTime(conv.updated_at)}</span>
+                      {conv.message_count > 0 && (
+                        <>
+                          <span className="text-xs">·</span>
+                          <span className="text-xs">
+                            {conv.message_count} msg{conv.message_count !== 1 ? "s" : ""}
+                          </span>
+                        </>
+                      )}
+                    </div>
+                  </button>
+                ))
+              )}
+            </div>
+          </>
+        )}
+      </aside>
+    </>
+  );
+});

apps/web/src/components/chat/MessageList.tsx

@@ -0,0 +1,319 @@
+"use client";
+
+import { useCallback, useState } from "react";
+import type { Message } from "./Chat";
+
+interface MessageListProps {
+  messages: Message[];
+  isLoading: boolean;
+  loadingQuip?: string | null;
+}
+
+/**
+ * Parse thinking content from message.
+ * Extracts <thinking>...</thinking> or <think>...</think> blocks.
+ */
+function parseThinking(content: string): { thinking: string | null; response: string } {
+  // Match <thinking>...</thinking> or <think>...</think> blocks
+  const thinkingRegex = /<(?:thinking|think)>([\s\S]*?)<\/(?:thinking|think)>/gi;
+  const matches = content.match(thinkingRegex);
+
+  if (!matches) {
+    return { thinking: null, response: content };
+  }
+
+  // Extract thinking content
+  let thinking = "";
+  for (const match of matches) {
+    const innerContent = match.replace(/<\/?(?:thinking|think)>/gi, "");
+    thinking += innerContent.trim() + "\n";
+  }
+
+  // Remove thinking blocks from response
+  const response = content.replace(thinkingRegex, "").trim();
+
+  return {
+    thinking: thinking.trim() || null,
+    response,
+  };
+}
+
+export function MessageList({ messages, isLoading, loadingQuip }: MessageListProps) {
+  return (
+    <div className="space-y-6" role="log" aria-label="Chat messages">
+      {messages.map((message) => (
+        <MessageBubble key={message.id} message={message} />
+      ))}
+
+      {isLoading && <LoadingIndicator quip={loadingQuip} />}
+    </div>
+  );
+}
+
+function MessageBubble({ message }: { message: Message }) {
+  const isUser = message.role === "user";
+  const [copied, setCopied] = useState(false);
+  const [thinkingExpanded, setThinkingExpanded] = useState(false);
+
+  // Parse thinking from content (or use pre-parsed thinking field)
+  const { thinking, response } = message.thinking
+    ? { thinking: message.thinking, response: message.content }
+    : parseThinking(message.content);
+
+  const handleCopy = useCallback(async () => {
+    try {
+      await navigator.clipboard.writeText(response);
+      setCopied(true);
+      setTimeout(() => setCopied(false), 2000);
+    } catch (err) {
+      console.error("Failed to copy:", err);
+    }
+  }, [response]);
+
+  return (
+    <div
+      className={`group flex gap-4 message-animate ${isUser ? "flex-row-reverse" : ""}`}
+      role="article"
+      aria-label={`${isUser ? "Your" : "AI Assistant"} message`}
+    >
+      {/* Avatar */}
+      <div
+        className="flex h-8 w-8 flex-shrink-0 items-center justify-center rounded-lg text-xs font-semibold"
+        style={{
+          backgroundColor: isUser
+            ? "rgb(var(--surface-2))"
+            : "rgb(var(--accent-primary))",
+          color: isUser ? "rgb(var(--text-secondary))" : "white",
+        }}
+        aria-hidden="true"
+      >
+        {isUser ? "You" : "AI"}
+      </div>
+
+      {/* Message Content */}
+      <div className={`flex max-w-[85%] flex-col gap-1.5 ${isUser ? "items-end" : "items-start"}`}>
+        {/* Message Header */}
+        <div
+          className={`flex items-center gap-2 text-xs ${isUser ? "flex-row-reverse" : ""}`}
+          style={{ color: "rgb(var(--text-muted))" }}
+        >
+          <span className="font-medium" style={{ color: "rgb(var(--text-secondary))" }}>
+            {isUser ? "You" : "AI Assistant"}
+          </span>
+          {/* Model indicator for assistant messages */}
+          {!isUser && message.model && (
+            <span
+              className="px-1.5 py-0.5 rounded text-[10px] font-medium"
+              style={{
+                backgroundColor: "rgb(var(--surface-2))",
+                color: "rgb(var(--text-tertiary))",
+              }}
+              title={message.provider ? `Provider: ${message.provider}` : undefined}
+            >
+              {message.model}
+            </span>
+          )}
+          {/* Token usage indicator for assistant messages */}
+          {!isUser && message.totalTokens !== undefined && message.totalTokens > 0 && (
+            <span
+              className="px-1.5 py-0.5 rounded text-[10px] font-medium"
+              style={{
+                backgroundColor: "rgb(var(--surface-2))",
+                color: "rgb(var(--text-muted))",
+              }}
+              title={`Prompt: ${message.promptTokens?.toLocaleString() || 0} tokens, Completion: ${message.completionTokens?.toLocaleString() || 0} tokens`}
+            >
+              {formatTokenCount(message.totalTokens)} tokens
+            </span>
+          )}
+          <span aria-label={`Sent at ${formatTime(message.createdAt)}`}>
+            {formatTime(message.createdAt)}
+          </span>
+        </div>
+
+        {/* Thinking Section - Collapsible */}
+        {thinking && !isUser && (
+          <div
+            className="rounded-lg overflow-hidden"
+            style={{
+              backgroundColor: "rgb(var(--surface-1))",
+              border: "1px solid rgb(var(--border-default))",
+            }}
+          >
+            <button
+              onClick={() => setThinkingExpanded(!thinkingExpanded)}
+              className="w-full flex items-center gap-2 px-3 py-2 text-xs font-medium hover:bg-black/5 dark:hover:bg-white/5 transition-colors"
+              style={{ color: "rgb(var(--text-secondary))" }}
+              aria-expanded={thinkingExpanded}
+            >
+              <svg
+                className={`h-3.5 w-3.5 transition-transform duration-200 ${thinkingExpanded ? "rotate-90" : ""}`}
+                fill="none"
+                viewBox="0 0 24 24"
+                stroke="currentColor"
+                strokeWidth={2}
+              >
+                <path d="m9 18 6-6-6-6" />
+              </svg>
+              <svg
+                className="h-3.5 w-3.5"
+                fill="none"
+                viewBox="0 0 24 24"
+                stroke="currentColor"
+                strokeWidth={2}
+              >
+                <path d="M9.663 17h4.673M12 3v1m6.364 1.636l-.707.707M21 12h-1M4 12H3m3.343-5.657l-.707-.707m2.828 9.9a5 5 0 117.072 0l-.548.547A3.374 3.374 0 0014 18.469V19a2 2 0 11-4 0v-.531c0-.895-.356-1.754-.988-2.386l-.548-.547z" />
+              </svg>
+              <span>Thinking</span>
+              <span
+                className="ml-auto text-xs"
+                style={{ color: "rgb(var(--text-muted))" }}
+              >
+                {thinkingExpanded ? "Hide" : "Show"} reasoning
+              </span>
+            </button>
+            {thinkingExpanded && (
+              <div
+                className="px-3 pb-3 text-xs leading-relaxed whitespace-pre-wrap font-mono"
+                style={{
+                  color: "rgb(var(--text-secondary))",
+                  borderTop: "1px solid rgb(var(--border-default))",
+                }}
+              >
+                {thinking}
+              </div>
+            )}
+          </div>
+        )}
+
+        {/* Message Body */}
+        <div
+          className="relative rounded-lg px-4 py-3"
+          style={{
+            backgroundColor: isUser
+              ? "rgb(var(--accent-primary))"
+              : "rgb(var(--surface-0))",
+            color: isUser ? "white" : "rgb(var(--text-primary))",
+            border: isUser ? "none" : "1px solid rgb(var(--border-default))",
+          }}
+        >
+          <p className="whitespace-pre-wrap text-sm leading-relaxed">
+            {response}
+          </p>
+
+          {/* Copy Button - appears on hover */}
+          <button
+            onClick={handleCopy}
+            className="absolute -right-2 -top-2 rounded-md border p-1.5 opacity-0 transition-all group-hover:opacity-100 focus:opacity-100"
+            style={{
+              backgroundColor: "rgb(var(--surface-0))",
+              borderColor: "rgb(var(--border-default))",
+              color: copied ? "rgb(var(--semantic-success))" : "rgb(var(--text-muted))",
+            }}
+            aria-label={copied ? "Copied!" : "Copy message"}
+            title={copied ? "Copied!" : "Copy to clipboard"}
+          >
+            {copied ? (
+              <svg className="h-3.5 w-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                <polyline points="20 6 9 17 4 12" />
+              </svg>
+            ) : (
+              <svg className="h-3.5 w-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                <rect x="9" y="9" width="13" height="13" rx="2" ry="2" />
+                <path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1" />
+              </svg>
+            )}
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+function LoadingIndicator({ quip }: { quip?: string | null }) {
+  return (
+    <div className="flex gap-4 message-animate" role="status" aria-label="AI is typing">
+      {/* Avatar */}
+      <div
+        className="flex h-8 w-8 flex-shrink-0 items-center justify-center rounded-lg text-xs font-semibold"
+        style={{ backgroundColor: "rgb(var(--accent-primary))" }}
+        aria-hidden="true"
+      >
+        <span className="text-white">AI</span>
+      </div>
+
+      {/* Loading Content */}
+      <div className="flex flex-col gap-1.5">
+        <div
+          className="flex items-center gap-2 text-xs"
+          style={{ color: "rgb(var(--text-muted))" }}
+        >
+          <span className="font-medium" style={{ color: "rgb(var(--text-secondary))" }}>
+            AI Assistant
+          </span>
+          <span>thinking...</span>
+        </div>
+
+        <div
+          className="rounded-lg border px-4 py-3"
+          style={{
+            backgroundColor: "rgb(var(--surface-0))",
+            borderColor: "rgb(var(--border-default))",
+          }}
+        >
+          <div className="flex items-center gap-2">
+            <div className="flex items-center gap-1.5">
+              <span
+                className="h-1.5 w-1.5 rounded-full animate-bounce"
+                style={{
+                  backgroundColor: "rgb(var(--accent-primary))",
+                  animationDelay: "0ms",
+                }}
+              />
+              <span
+                className="h-1.5 w-1.5 rounded-full animate-bounce"
+                style={{
+                  backgroundColor: "rgb(var(--accent-primary))",
+                  animationDelay: "150ms",
+                }}
+              />
+              <span
+                className="h-1.5 w-1.5 rounded-full animate-bounce"
+                style={{
+                  backgroundColor: "rgb(var(--accent-primary))",
+                  animationDelay: "300ms",
+                }}
+              />
+            </div>
+            {quip && (
+              <span
+                className="text-sm italic animate-fade-in"
+                style={{ color: "rgb(var(--text-muted))" }}
+              >
+                {quip}
+              </span>
+            )}
+          </div>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+function formatTime(isoString: string): string {
+  try {
+    const date = new Date(isoString);
+    return date.toLocaleTimeString([], { hour: "2-digit", minute: "2-digit" });
+  } catch {
+    return "";
+  }
+}
+
+function formatTokenCount(tokens: number): string {
+  if (tokens >= 1000000) {
+    return `${(tokens / 1000000).toFixed(1)}M`;
+  } else if (tokens >= 1000) {
+    return `${(tokens / 1000).toFixed(1)}K`;
+  }
+  return tokens.toString();
+}

apps/web/src/components/chat/index.ts

@@ -0,0 +1,17 @@
+/**
+ * Chat Components
+ * 
+ * Migrated from jarvis-fe. These components provide the chat interface
+ * for interacting with the AI brain service.
+ * 
+ * Usage:
+ * ```tsx
+ * import { Chat, MessageList, ChatInput } from '@/components/chat';
+ * ```
+ */
+
+export { Chat, type ChatRef, type Message, type NewConversationData } from './Chat';
+export { ChatInput } from './ChatInput';
+export { MessageList } from './MessageList';
+export { ConversationSidebar, type ConversationSidebarRef } from './ConversationSidebar';
+export { BackendStatusBanner } from './BackendStatusBanner';