"use client"; import { useState, useCallback, useRef } from "react"; import { ChatThread, StreamingText, PromptBox, FeedbackBar, ThinkingBlock, ToolCall, CodeBlock, TokenUsage, ModelSelector, type ModelOption, } from "@arc-lo/ui"; /* ─── Models ─────────────────────────────────────────────────────── */ const MODELS: ModelOption[] = [ { id: "claude-sonnet", name: "Claude Sonnet", description: "Fast and capable for most coding tasks", badge: "Fast", }, { id: "claude-opus", name: "Claude Opus", description: "Most powerful for complex reasoning", badge: "New", }, { id: "gpt-4", name: "GPT-4", description: "OpenAI flagship model", }, ]; /* ─── Sample data ────────────────────────────────────────────────── */ const THINKING_TEXT = `The user is reporting a JWT validation bug in their auth middleware. Let me think through the common issues: 1. The middleware might not be verifying the token signature correctly 2. Token expiration checks could be missing or improperly configured 3. The issuer/audience claims might not be validated 4. The secret key could be loaded incorrectly I should read the current middleware file first, then identify the specific bug and propose a fix.`; const READ_FILE_INPUT = `{ "path": "src/middleware/auth.ts" }`; const READ_FILE_OUTPUT = `export function validateToken(token: string) { const decoded = jwt.decode(token); // BUG: using decode() instead of verify() // This does NOT validate the signature! if (!decoded) return null; return decoded; }`; const EDIT_FILE_INPUT = `{ "path": "src/middleware/auth.ts", "old_string": "const decoded = jwt.decode(token);", "new_string": "const decoded = jwt.verify(token, process.env.JWT_SECRET);" }`; const EDIT_FILE_OUTPUT = `File edited successfully. - src/middleware/auth.ts: 1 replacement made`; const RESPONSE_TEXT = `I found and fixed the bug in your auth middleware. The issue was that \`jwt.decode()\` was being used instead of \`jwt.verify()\`. **The problem:** \`jwt.decode()\` only parses the token payload without checking the cryptographic signature. This means any forged token would be accepted as valid. **The fix:** Replaced it with \`jwt.verify(token, process.env.JWT_SECRET)\` which properly validates the signature, expiration, and claims against your secret key. I also added proper error handling for expired and malformed tokens.`; const FIXED_CODE = `import jwt from "jsonwebtoken"; export function validateToken(token: string) { try { const decoded = jwt.verify(token, process.env.JWT_SECRET, { algorithms: ["HS256"], issuer: process.env.JWT_ISSUER, }); return decoded; } catch (err) { if (err instanceof jwt.TokenExpiredError) { throw new AuthError("Token has expired", 401); } if (err instanceof jwt.JsonWebTokenError) { throw new AuthError("Invalid token", 401); } throw err; } }`; /* ─── Types ──────────────────────────────────────────────────────── */ type Phase = | "idle" | "thinking" | "tool-read" | "tool-edit" | "streaming" | "done"; /* ─── Component ──────────────────────────────────────────────────── */ export function CodingAgentExample() { const [model, setModel] = useState("claude-sonnet"); const [input, setInput] = useState(""); const [phase, setPhase] = useState("idle"); const [userMessage, setUserMessage] = useState(""); const timerRef = useRef>(undefined); const runSimulation = useCallback((text: string) => { if (!text.trim()) return; setUserMessage(text.trim()); setInput(""); setPhase("thinking"); // thinking -> tool-read timerRef.current = setTimeout(() => { setPhase("tool-read"); // tool-read -> tool-edit timerRef.current = setTimeout(() => { setPhase("tool-edit"); // tool-edit -> streaming timerRef.current = setTimeout(() => { setPhase("streaming"); }, 1200); }, 1000); }, 2000); }, []); const handleSubmit = useCallback( (text: string) => { if (phase !== "idle" && phase !== "done") return; runSimulation(text); }, [phase, runSimulation], ); const isSubmitting = phase !== "idle" && phase !== "done"; const showConversation = phase !== "idle"; return (

{/* ─── Model selector header ───────────────────────────────── */}

{phase === "done" && ( )}

{/* ─── Chat area ───────────────────────────────────────────── */} {/* Empty state */} {!showConversation && (

Coding Agent

I can read, write, and fix code across your project.

)} {/* User message */} {showConversation && ( Y

} > {userMessage} )} {/* Agent response */} {showConversation && ( A } >

{/* Thinking block */}

{THINKING_TEXT}

{/* Tool call: read_file */} {(phase === "tool-read" || phase === "tool-edit" || phase === "streaming" || phase === "done") && ( {READ_FILE_INPUT} {READ_FILE_OUTPUT} )} {/* Tool call: edit_file */} {(phase === "tool-edit" || phase === "streaming" || phase === "done") && ( {EDIT_FILE_INPUT} {EDIT_FILE_OUTPUT} )} {/* Streaming response */} {(phase === "streaming" || phase === "done") && ( <> {phase === "streaming" ? ( setPhase("done")} > ) : (

{RESPONSE_TEXT}

)} )} {/* Code block */} {phase === "done" && ( )} {/* Feedback bar */} {phase === "done" && ( )}

)} {/* ─── Prompt box ──────────────────────────────────────────── */}

Enter to send

); }