Create Agent TUI
Scaffolds a complete agent TUI in TypeScript targeting OpenRouter. The generated project uses
for the inner loop (model calls, tool execution, stop conditions) and provides the outer shell: a customizable terminal interface, configuration, session management, tool definitions, and an entry point.
Architecture draws from three production agent systems:
- pi-mono/coding-agent — three-layer separation, JSONL sessions, pluggable tool operations
- Claude Code — tool metadata (read-only, destructive, approval), system prompt composition
- Codex CLI — layered config, approval flow with session caching, structured logging
Prerequisites
- Node.js 18+
- from openrouter.ai/settings/keys
- For full SDK reference, see the
openrouter-typescript-sdk
skill
Decision Tree
| User wants to... | Action |
|---|
| Build a new agent from scratch | Present checklist below → follow Generation Workflow |
| Add tools to an existing harness | Read references/tools.md, present tool checklist only |
| Add a harness module | Read references/modules.md, generate the module |
| Add an API server entry point | Read references/server-entry-points.md |
Interactive Tool Checklist
Present this as a multi-select checklist. Items marked ON are pre-selected defaults.
OpenRouter Server Tools (server-side, zero implementation)
| Tool | Type string | Default | Config |
|---|
| Web Search | | ON | engine, max_results, domain filtering |
| Datetime | | ON | timezone |
| Image Generation | openrouter:image_generation
| OFF | model, quality, size, format |
Server tools go in the
array alongside user-defined tools. No client code needed — OpenRouter executes them.
User-Defined Tools (client-side, generated into src/tools/)
| Tool | Default | Description |
|---|
| File Read | ON | Read files with offset/limit, detect images |
| File Write | ON | Write/create files, auto-create directories |
| File Edit | ON | Search-and-replace with diff validation |
| Glob/Find | ON | File discovery by glob pattern |
| Grep/Search | ON | Content search by regex |
| Directory List | ON | List directory contents |
| Shell/Bash | ON | Execute commands with timeout and output capture |
| JS REPL | OFF | Persistent Node.js environment |
| Sub-agent Spawn | OFF | Delegate tasks to child agents |
| Plan/Todo | OFF | Track multi-step task progress |
| Request User Input | OFF | Structured multiple-choice questions |
| Web Fetch | OFF | Fetch and extract text from web pages |
| View Image | OFF | Read local images as base64 |
| Custom Tool Template | ON | Empty skeleton for domain-specific tools |
Harness Modules (architectural components)
| Module | Default | Description |
|---|
| Session Persistence | ON | JSONL append-only conversation log |
| ASCII Logo Banner | OFF | Custom ASCII art banner on startup — ask for project name |
| Context Compaction | OFF | Summarize older messages when context is long |
| System Prompt Composition | OFF | Assemble instructions from static + dynamic context |
| Tool Permissions / Approval | OFF | Gate dangerous tools behind user confirmation |
| Structured Event Logging | OFF | Emit events for tool calls, API requests, errors |
| -file References | OFF | to attach file content to next message |
| Shell Shortcut | OFF | to run shell and inject output into context |
| Multi-line Input | OFF | Shift+Enter for multi-line (requires raw terminal mode) |
Slash Commands (user-facing REPL commands)
| Command | Default | Description |
|---|
| ON | Switch model via OpenRouter API |
| ON | Start a fresh conversation |
| ON | List available commands |
| OFF | Manually trigger context compaction |
| OFF | Show session metadata and token usage |
| OFF | Save conversation as Markdown |
When slash commands are enabled, generate
with a command registry. See
references/slash-commands.md for specs.
Visual Customization (present as single-select for each)
Input style — how the prompt looks. See references/input-styles.md:
| Style | Default | Description |
|---|
| ON | Full-width background box with prompt, adapts to terminal theme |
| | Horizontal lines above and below input |
| | Simple readline prompt, no escape sequences |
| Other | | User describes what they want — implement a custom input style |
Tool display — how tool calls appear during execution. See references/tool-display.md:
| Style | Default | Description |
|---|
| ON | Bold action labels with tree-branch output |
| | Per-call / markers with args and timing |
| | Aggregated one-liner summaries |
| | No tool output |
| Other | | User describes what they want — implement a custom display |
Loader animation — shown while waiting for model response. See references/loader.md:
| Style | Default | Description |
|---|
| ON | Braille dot spinner (⠋⠙⠹…) to the left of the text |
| | Scrolling color shimmer over the loader text |
| | Trailing dots () |
| Other | | User describes what they want — implement a custom animation |
Also ask for the
loader text (default:
).
Generation Workflow
After getting checklist selections, follow this workflow:
- [ ] Generate package.json with dependencies
- [ ] Generate src/config.ts (add showBanner field if ASCII Logo Banner is ON)
- [ ] Generate src/tools/index.ts wiring selected tools + server tools
- [ ] Generate selected tool files in src/tools/ (see Tool Pattern below, specs in references/tools.md)
- [ ] Generate src/agent.ts (core runner)
- [ ] Generate selected harness modules (specs in references/modules.md)
- [ ] Generate src/terminal-bg.ts (adaptive input background — see references/tui.md)
- [ ] Generate input style functions in src/cli.ts (block/bordered/plain — see references/input-styles.md)
- [ ] Generate src/renderer.ts (tool display — see references/tool-display.md)
- [ ] Generate src/loader.ts (loader animation — see references/loader.md)
- [ ] If slash commands selected: generate src/commands.ts (see references/slash-commands.md)
- [ ] If ASCII Logo Banner is ON: generate src/banner.ts (see ASCII Logo Banner section below)
- [ ] Generate src/cli.ts entry point (or src/server.ts — see references/server-entry-points.md)
- [ ] Generate .env.example with OPENROUTER_API_KEY=
- [ ] Verify: run npx tsc --noEmit to check types
Tool Pattern
All user-defined tools follow this pattern using
. Here is one complete example — all other tools in
references/tools.md follow the same shape:
typescript
import { tool } from '@openrouter/agent/tool';
import { z } from 'zod';
import { readFile, stat } from 'fs/promises';
export const fileReadTool = tool({
name: 'file_read',
description: 'Read the contents of a file at the given path',
inputSchema: z.object({
path: z.string().describe('Absolute path to the file'),
offset: z.number().optional().describe('Start reading from this line (1-indexed)'),
limit: z.number().optional().describe('Maximum number of lines to return'),
}),
execute: async ({ path, offset, limit }) => {
try {
const content = await readFile(path, 'utf-8');
const lines = content.split('\n');
const start = offset ? offset - 1 : 0;
const end = limit ? start + limit : lines.length;
const slice = lines.slice(start, end);
return {
content: slice.join('\n'),
totalLines: lines.length,
...(end < lines.length && { truncated: true, nextOffset: end + 1 }),
};
} catch (err: any) {
if (err.code === 'ENOENT') return { error: `File not found: ${path}` };
if (err.code === 'EACCES') return { error: `Permission denied: ${path}` };
return { error: err.message };
}
},
});
For specs of all other tools, see references/tools.md.
Core Files
These files are always generated. The agent adapts them based on checklist selections.
package.json
Initialize the project and install dependencies at their latest versions:
bash
npm init -y
npm pkg set type=module
npm pkg set scripts.start="tsx src/cli.ts"
npm pkg set scripts.dev="tsx watch src/cli.ts"
npm install @openrouter/agent glob zod
npm install -D tsx typescript @types/node
tsconfig.json
json
{
"compilerOptions": {
"target": "ES2022",
"module": "Node16",
"moduleResolution": "Node16",
"outDir": "dist",
"strict": true,
"esModuleInterop": true,
"skipLibCheck": true
},
"include": ["src"]
}
src/config.ts
typescript
import { readFileSync, existsSync } from 'fs';
import { resolve } from 'path';
export interface DisplayConfig {
toolDisplay: 'emoji' | 'grouped' | 'minimal' | 'hidden';
reasoning: boolean;
inputStyle: 'block' | 'bordered' | 'plain';
}
export interface AgentConfig {
apiKey: string;
model: string;
systemPrompt: string;
maxSteps: number;
maxCost: number;
sessionDir: string;
showBanner: boolean;
display: DisplayConfig;
slashCommands: boolean;
}
const DEFAULTS: AgentConfig = {
apiKey: '',
model: 'anthropic/claude-opus-4.7',
systemPrompt: [
'You are a coding assistant with access to tools for reading, writing, editing, and searching files, and running shell commands.',
'',
'Current working directory: {cwd}',
'',
'Guidelines:',
'- Use your tools proactively. Explore the codebase to find answers instead of asking the user.',
'- Keep working until the task is fully resolved before responding.',
'- Do not guess or make up information — use your tools to verify.',
'- Be concise and direct.',
'- Show file paths clearly when working with files.',
'- Prefer grep and glob tools over shell commands for file search.',
'- When editing code, make minimal targeted changes consistent with the existing style.',
].join('\n'),
maxSteps: 20,
maxCost: 1.0,
sessionDir: '.sessions',
showBanner: false,
display: { toolDisplay: 'grouped', reasoning: false, inputStyle: 'block' },
slashCommands: true,
};
export function loadConfig(overrides: Partial<AgentConfig> = {}): AgentConfig {
let config = { ...DEFAULTS };
const configPath = resolve('agent.config.json');
if (existsSync(configPath)) {
const file = JSON.parse(readFileSync(configPath, 'utf-8'));
if (file.display) {
config.display = { ...config.display, ...file.display };
}
config = { ...config, ...file, display: config.display };
}
if (process.env.OPENROUTER_API_KEY) config.apiKey = process.env.OPENROUTER_API_KEY;
if (process.env.AGENT_MODEL) config.model = process.env.AGENT_MODEL;
if (process.env.AGENT_MAX_STEPS) config.maxSteps = Number(process.env.AGENT_MAX_STEPS);
if (process.env.AGENT_MAX_COST) config.maxCost = Number(process.env.AGENT_MAX_COST);
if (overrides.display) {
config.display = { ...config.display, ...overrides.display };
}
config = { ...config, ...overrides, display: config.display };
if (!config.apiKey) throw new Error('OPENROUTER_API_KEY is required.');
return config;
}
src/tools/index.ts
Adapt imports based on checklist selections. This example includes all default-ON tools:
typescript
import { serverTool } from '@openrouter/agent';
import { fileReadTool } from './file-read.js';
import { fileWriteTool } from './file-write.js';
import { fileEditTool } from './file-edit.js';
import { globTool } from './glob.js';
import { grepTool } from './grep.js';
import { listDirTool } from './list-dir.js';
import { shellTool } from './shell.js';
export const tools = [
// User-defined tools — executed client-side
fileReadTool,
fileWriteTool,
fileEditTool,
globTool,
grepTool,
listDirTool,
shellTool,
// Server tools — executed by OpenRouter, no client implementation needed
serverTool({ type: 'openrouter:web_search' }),
serverTool({ type: 'openrouter:datetime', parameters: { timezone: 'UTC' } }),
];
src/agent.ts
typescript
import { OpenRouter } from '@openrouter/agent';
import type { Item } from '@openrouter/agent';
import { stepCountIs, maxCost } from '@openrouter/agent/stop-conditions';
import type { AgentConfig } from './config.js';
import { tools } from './tools/index.js';
export type ChatMessage = { role: 'user' | 'assistant' | 'system'; content: string };
export type AgentEvent =
| { type: 'text'; delta: string }
| { type: 'tool_call'; name: string; callId: string; args: Record<string, unknown> }
| { type: 'tool_result'; name: string; callId: string; output: string }
| { type: 'reasoning'; delta: string };
export async function runAgent(
config: AgentConfig,
input: string | ChatMessage[],
options?: { onEvent?: (event: AgentEvent) => void; signal?: AbortSignal },
) {
const client = new OpenRouter({ apiKey: config.apiKey });
const result = client.callModel({
model: config.model,
instructions: config.systemPrompt.replace('{cwd}', process.cwd()),
input: input as string | Item[],
tools,
stopWhen: [stepCountIs(config.maxSteps), maxCost(config.maxCost)],
});
if (options?.onEvent) {
let lastTextLen = 0;
const callNames = new Map<string, string>();
for await (const item of result.getItemsStream()) {
if (options?.signal?.aborted) break;
if (item.type === 'message') {
const text = item.content
?.filter((c): c is { type: 'output_text'; text: string } => 'text' in c)
.map((c) => c.text)
.join('') ?? '';
if (text.length > lastTextLen) {
options.onEvent({ type: 'text', delta: text.slice(lastTextLen) });
lastTextLen = text.length;
}
} else if (item.type === 'function_call') {
callNames.set(item.callId, item.name);
if (item.status === 'completed') {
const args = (() => { try { return item.arguments ? JSON.parse(item.arguments) : {}; } catch { return {}; } })();
options.onEvent({ type: 'tool_call', name: item.name, callId: item.callId, args });
}
} else if (item.type === 'function_call_output') {
const out = typeof item.output === 'string' ? item.output : JSON.stringify(item.output);
options.onEvent({
type: 'tool_result',
name: callNames.get(item.callId) ?? 'unknown',
callId: item.callId,
output: out.length > 200 ? out.slice(0, 200) + '…' : out,
});
} else if (item.type === 'reasoning') {
const text = item.summary?.map((s: { text: string }) => s.text).join('') ?? '';
if (text) options.onEvent({ type: 'reasoning', delta: text });
}
}
}
const response = await result.getResponse();
return { text: response.outputText ?? '', usage: response.usage, output: response.output };
}
export async function runAgentWithRetry(
config: AgentConfig,
input: string | ChatMessage[],
options?: { onEvent?: (event: AgentEvent) => void; signal?: AbortSignal; maxRetries?: number },
) {
for (let attempt = 0, max = options?.maxRetries ?? 3; attempt <= max; attempt++) {
try { return await runAgent(config, input, options); }
catch (err: any) {
const s = err?.status ?? err?.statusCode;
if (!(s === 429 || (s >= 500 && s < 600)) || attempt === max) throw err;
await new Promise((r) => setTimeout(r, Math.min(1000 * 2 ** attempt, 30000)));
}
}
throw new Error('Unreachable');
}
src/cli.ts
Three input styles are supported:
(background box),
(horizontal lines), and
(simple caret). See
references/input-styles.md for full implementations of
,
, and the
dispatcher.
typescript
import { createInterface } from 'readline';
import { loadConfig } from './config.js';
import { runAgentWithRetry, type AgentEvent } from './agent.js';
import { detectBg } from './terminal-bg.js';
// import { styledReadLine, borderedReadLine } from ... — see references/input-styles.md
const DIM = '\x1b[2m';
const RESET = '\x1b[0m';
const BOLD = '\x1b[1m';
const CYAN = '\x1b[36m';
const GREEN = '\x1b[32m';
const YELLOW = '\x1b[33m';
const GRAY = '\x1b[90m';
function formatTokens(n: number): string {
return n >= 1000 ? `${(n / 1000).toFixed(1)}k` : String(n);
}
function summarizeArgs(name: string, args: Record<string, unknown>): string {
const key = { shell: 'command', file_read: 'path', file_write: 'path',
file_edit: 'path', glob: 'pattern', grep: 'pattern', web_search: 'query',
}[name] ?? Object.keys(args)[0];
if (!key || !(key in args)) return '';
const val = String(args[key]);
return `${key}=${val.length > 40 ? val.slice(0, 40) + '…' : val}`;
}
async function main() {
const config = loadConfig();
const BG_INPUT = config.display.inputStyle === 'block' ? await detectBg() : '';
// Banner
const width = Math.min(process.stdout.columns || 60, 60);
const line = GRAY + '─'.repeat(width) + RESET;
console.log(`\n${line}`);
console.log(` ${BOLD}My Agent${RESET} ${DIM}v0.1.0${RESET}`);
console.log(` ${DIM}model${RESET} ${CYAN}${config.model}${RESET}`);
if (config.slashCommands) console.log(` ${DIM}/model to change${RESET}`);
console.log(`${line}\n`);
const rl = createInterface({ input: process.stdin, output: process.stdout, prompt: `${GREEN}>${RESET} ` });
async function getInput(): Promise<string> {
switch (config.display.inputStyle) {
case 'block': return styledReadLine(BG_INPUT);
case 'bordered': return borderedReadLine();
case 'plain':
default:
return new Promise((r) => { rl.prompt(); rl.once('line', r); });
}
}
while (true) {
const input = await getInput();
const trimmed = input.trim();
if (!trimmed) continue;
if (config.display.inputStyle !== 'plain') {
const cwd = process.cwd().replace(process.env.HOME ?? '', '~');
process.stdout.write(`\x1b[K ${DIM}${cwd}${RESET}\n`);
}
if (trimmed.toLowerCase() === 'exit') { process.exit(0); }
console.log();
let streaming = false, started = false;
const toolStart = new Map<string, number>();
const dots = ['·', '··', '···'];
let di = 0;
const spin = setInterval(() => {
if (!started) process.stdout.write(`\r${DIM}${dots[di++ % 3]}${RESET}`);
}, 300);
const handleEvent = (event: AgentEvent) => {
if (!started) { started = true; process.stdout.write('\r\x1b[K'); }
if (event.type === 'text') { streaming = true; process.stdout.write(event.delta); }
else if (event.type === 'tool_call') {
if (streaming) { process.stdout.write('\n'); streaming = false; }
toolStart.set(event.callId, Date.now());
const args = summarizeArgs(event.name, event.args);
console.log(` ${YELLOW}⚡${RESET} ${DIM}${event.name}${args ? ' ' + args : ''}${RESET}`);
} else if (event.type === 'tool_result') {
const ms = Date.now() - (toolStart.get(event.callId) ?? Date.now());
console.log(` ${GREEN}✓${RESET} ${DIM}${event.name} (${(ms / 1000).toFixed(1)}s)${RESET}`);
started = false;
}
};
try {
const result = await runAgentWithRetry(config, trimmed, { onEvent: handleEvent });
clearInterval(spin);
if (streaming) process.stdout.write(RESET);
const inT = result.usage?.inputTokens ?? 0;
const outT = result.usage?.outputTokens ?? 0;
console.log(`\n${GRAY} ${formatTokens(inT)} in · ${formatTokens(outT)} out${RESET}\n`);
} catch (err: any) {
clearInterval(spin);
if (streaming) process.stdout.write(RESET);
console.log(`\n${YELLOW} Error: ${err.message}${RESET}\n`);
}
}
}
main();
ASCII Logo Banner
When
is selected, ask the user for their project name, then generate
with ASCII art of that name. Use a block-letter style with the
character for the art. The banner should fit in a 60-column terminal.
src/banner.ts
Generate ASCII art for the user's project name. Example for a project called "ACME":
typescript
const RESET = '\x1b[0m';
const BOLD = '\x1b[1m';
const DIM = '\x1b[2m';
const CYAN = '\x1b[36m';
const LOGO = `
█████╗ ██████╗███╗ ███╗███████╗
██╔══██╗██╔════╝████╗ ████║██╔════╝
███████║██║ ██╔████╔██║█████╗
██╔══██║██║ ██║╚██╔╝██║██╔══╝
██║ ██║╚██████╗██║ ╚═╝ ██║███████╗
╚═╝ ╚═╝ ╚═════╝╚═╝ ╚═╝╚══════╝`;
export function printBanner(model: string): void {
console.log(CYAN + BOLD + LOGO + RESET);
console.log(` ${DIM}model ${RESET}${model}\n`);
}
Adapt the ASCII art to the user's actual project name. Keep it to one or two short words that fit in 60 columns.
Wire into src/cli.ts
Add at the top of
, before the text banner, when
is selected:
typescript
import { printBanner } from './banner.js';
// In main(), replace the text banner with:
if (config.showBanner) {
printBanner(config.model);
} else {
// fall back to the text banner from the cli.ts template above
}
Add
to
(default
). Enable via
or
loadConfig({ showBanner: true })
.
Reference Files
For content beyond the core files:
- references/tools.md — Specs for all user-defined tools: file-read, file-write, file-edit, glob, grep, list-dir, shell, js-repl, sub-agent, plan, request-input, web-fetch, view-image, custom template
- references/modules.md — Harness modules: session persistence, context compaction, system prompt composition, tool approval, structured logging
- references/tui.md — Terminal background detection, adaptive input background
- references/tool-display.md — Tool display styles: emoji, grouped, minimal; TuiRenderer class, per-tool colors, formatters
- references/input-styles.md — Input styles: block (background box), bordered (horizontal lines), plain (simple caret)
- references/loader.md — Loader animations: gradient (scrolling shimmer), spinner (braille dots), minimal (trailing dots)
- references/slash-commands.md — Slash command registry: /model, /new, /help, /compact, /session, /export
- references/system-prompt.md — Default system prompt, buildSystemPrompt(), customization guide
- references/server-entry-points.md — Express/Hono API server entry point with SSE streaming, plus extension points (MCP, WebSocket, dynamic models)