Photon

Define intent once. Deliver everywhere.

Photon turns a single TypeScript file into:

• MCP server for AI agents
• CLI tool for automation
• Web interface for humans

Photon is free and open source software released under the MIT license.

Interfaces are optional. Intent is mandatory.

---

One definition. Multiple interfaces.

---

Example

// hello.photon.ts
export default class Hello {
  greet(name: string) {
    return `Hello, ${name}!`;
  }
}

That's a complete photon. From this single file you get:

$ photon cli hello greet --name Ada        # CLI
$ photon                                    # Web UI at localhost:3008
$ photon mcp hello                          # MCP server for Claude, Cursor, etc.

No decorators. No registration. No server boilerplate. Just define the intent. Photon handles the rest.

---

Why Photon Exists

Most software is built around interfaces: web apps, CLI tools, APIs, and now MCP servers for AI agents. But the underlying logic is often the same.

Photon starts from a different place: capture the intent once in a TypeScript file and let the system expose it through multiple interfaces — CLI tools, web interfaces, and MCP servers.

One definition. Multiple surfaces.

---

Quick Start

From zero to an MCP server connected to Claude Desktop in three commands:

npm install -g @portel/photon
photon new my-tool                  # Scaffolds ./my-tool.photon.ts in your CWD
photon mcp install my-tool          # Registers it in Claude Desktop's config
# Restart Claude Desktop. Your tool is live.

Prefer the web dashboard? Skip step 3 and run photon instead — it opens Beam, the auto-generated UI.

Or try without installing globally:

npx @portel/photon new my-tool
npx @portel/photon mcp install my-tool

Requires Node.js 20+. TypeScript is compiled internally; no tsconfig.json needed.

---

How It Works

You write a TypeScript class. Methods are your capabilities. Types describe what's valid. Comments explain the intent. Photon reads all of it and generates three interfaces from one file. Same logic. Same validation. Same data.

analytics.photon.ts  →  Web UI (Beam)  ·  CLI  ·  MCP Server for AI

The more you express, the more Photon derives:

What you write	What Photon derives
Method signatures	Tool definitions: names, inputs, outputs
Type annotations	Input validation rules, UI field types
JSDoc comments	Documentation for AI clients and human users
Constructor parameters	Config UI, environment variable mapping
@tags	Validation, formatting, scheduling, webhooks

When you add a @param city {@pattern ^[a-zA-Z\s]+$} annotation, Beam validates it in the form, the CLI validates it before running, and the MCP schema enforces it for the AI. One annotation. Three consumers.

---

Beam: Human Exploration

Beam is the web dashboard. Every photon becomes an interactive form automatically. Run photon. That's the whole command.

The UI is fully auto-generated from your method signatures: field types, validation, defaults, layouts. You never write frontend code. When you add a {@choice a,b,c} tag to a parameter, Beam renders a dropdown. When you mark a string as {@format email}, the field validates email format. The UI evolves as your code does.

When forms aren't the right interface for what you're building, you can replace Beam's auto-generated view with your own HTML. A global named after your photon is auto-injected (e.g., analytics.onResult(data => ...)) — no framework required.

Custom UIs follow the MCP Apps Extension (SEP-1865) standard and work across compatible hosts. See the Custom UI Guide.

---

AI Agents: Machine Invocation

photon info analytics --mcp

{
  "mcpServers": {
    "analytics": {
      "command": "photon",
      "args": ["mcp", "analytics"]
    }
  }
}

Paste into your AI client's config. Your photon is now an MCP server. Claude can call your methods. Cursor can call your methods. Any MCP-compatible host can call your methods.

The AI sees the same thing a human sees in Beam: the method names, the parameter descriptions from your JSDoc, the validation rules from your types. The JSDoc comment you wrote to document the tool for yourself is what Claude reads to decide when and how to call it.

The MCP tools themselves work with Claude Desktop, Claude Code, Cursor, and any MCP-compatible client.

When your photon has a custom UI, clients that support the MCP Apps Extension render it natively, no separate app needed. The photon below is running inside Claude Desktop, same UI, same data as Beam.

---

How a Photon Evolves

Here is how a photon grows. Each step adds one thing and gets multiple capabilities from it.

Add comments: AI understands your intent

/**
 * Weather - Check weather forecasts worldwide
 */
export default class Weather {
  /**
   * Get the weather forecast for a city
   * @param city City name (e.g., "London")
   */
  async forecast(params: { city: string }) { ... }
}

The class description becomes how AI clients introduce the tool to users. The @param description is what the AI reads before deciding what value to pass. Same comments. Human help text and AI contract at once.

Add a constructor: configuration appears

export default class Weather {
  constructor(
    private apiKey: string,
    private units: string = 'metric'
  ) {}

  async forecast(params: { city: string }) {
    const res = await fetch(`...?appid=${this.apiKey}&units=${this.units}`);
    return await res.json();
  }
}

apiKey becomes a password field in the Beam settings panel and maps to the WEATHER_API_KEY environment variable. units gets a text input with 'metric' pre-filled. You declared what you need. Photon built the configuration surface.

Add tags: behavior extends across all surfaces

/**
 * @dependencies node-fetch@^3.0.0
 */
export default class Weather {
  /**
   * @param city City name {@example London} {@pattern ^[a-zA-Z\s]+$}
   * @param days Number of days {@min 1} {@max 7}
   * @format table
   */
  async forecast(params: { city: string; days?: number }) { ... }
}

@dependencies installs node-fetch automatically on first run, no npm install needed. The {@pattern} validates in the form, the CLI, and the MCP schema simultaneously. days becomes a number spinner with bounds. @format table renders the result as a table in Beam. One annotation, three surfaces.

System CLI dependencies

If your photon wraps a command-line tool, declare it and Photon enforces it at load time:

/**
 * @cli ffmpeg - https://ffmpeg.org/download.html
 */
export default class VideoProcessor {
  async convert({ input, format }: { input: string; format: string }) {
    // ffmpeg is guaranteed to exist when this runs
  }
}

---

What Comes for Free

Things you don't build because Photon handles them:

Auto-UI	Forms, field types, validation, layouts generated from your signatures
Stateful instances	Multiple named instances of the same photon, each with isolated state
Persistent memory	this.memory gives your photon per-instance key-value storage, no database needed
Scheduled execution	@scheduled runs any method on a cron schedule
Webhooks	@webhook exposes any method as an HTTP endpoint
OAuth (client)	Built-in OAuth 2.0 flows for Google, GitHub, Microsoft
OAuth Authorization Server	Issue tokens to MCP clients yourself: CIMD + DCR, PKCE, OIDC id_token, RFC 8693 token exchange
SQLite persistence	Audit log, execution history, and OAuth grants survive daemon restart (bun:sqlite or better-sqlite3)
Daemon ops	photon ps lists and controls scheduled jobs, webhooks, and live sessions
Distributed locks	@locked serializes access: one caller at a time, across processes
Cross-photon calls	this.call() invokes another photon's methods
Real-time events	this.emit() fires named events to the browser UI with zero wiring
Live rendering	this.render() pushes formatted output to CLI and Beam in real time
Delegated LLM	this.sample() asks the driving agent's model to generate text — no API key, agent pays
Inline confirm / input	this.confirm() and this.elicit() route through the client's native UI (Beam dialog, Claude prompt)
Scoped remote access	photon claim generates a short-lived code to scope a remote MCP session to one directory
Standalone binaries	photon build compiles any photon to a single executable via Bun
Dependency management	@dependencies auto-installs npm packages on first run

---

Coordination: Locks + Events

Two primitives. Together they unlock a class of things that are surprisingly hard to build today.

Locks serialize access. When a method is marked @locked, only one caller can execute at a time, whether that caller is a human in Beam, a CLI script, or an AI agent. Everyone else waits their turn.

Events push state changes to any browser UI in real time. this.emit({ event: 'boardUpdated', data: board }) on the server becomes chess.onBoardUpdated(handler) in your custom UI — named after your photon file. No WebSockets to configure. No polling. Events are delivered via SSE through the MCP Streamable HTTP transport.

Together: turn-based coordination with live state.

export default class Chess {
  /** Make a move. Locks ensure human and AI alternate turns. */
  /** @locked */
  async move(params: { from: string; to: string }) {
    const result = await this.applyMove(params.from, params.to);

    // Browser UI updates instantly, no polling needed
    this.emit({ event: 'boardUpdated', data: result.board });
    this.emit({ event: 'turnChanged', data: { next: result.nextPlayer } });

    return result;
  }
}

// In your custom UI (ui/chess.html)
// The global `chess` is auto-injected, named after your photon file
chess.onBoardUpdated(board => renderBoard(board));
chess.onTurnChanged(({ next }) => showTurn(next));

// Call server methods directly
chess.move({ from: 'e2', to: 'e4' });

A human moves through Beam. Claude is configured with the MCP server. The lock ensures they truly alternate. Events keep the board live on both sides. That's a fully functional turn-based chess game, human vs AI, in about 50 lines of application logic.

The same pattern applies beyond games: approval workflows where a human reviews before AI continues, collaborative tools where edits from any source appear instantly, simulations where steps must execute in strict sequence, any system where who acts next matters.

---

MCP Primitives on this

The MCP protocol's user-facing primitives are surfaced as plain methods on every photon instance — no decorators, no capability flags, no SDK imports. The runtime routes each call through whichever surface the request arrived on (Beam, Claude Desktop, Cursor, CLI).

export default class Editor {
  async summarize(params: { text: string }) {
    // Ask the driving agent's LLM. No API key. Agent pays.
    return await this.sample({
      prompt: `Summarize in one sentence:\n\n${params.text}`,
      maxTokens: 128,
    });
  }

  async deploy() {
    if (!(await this.confirm('Ship to production?'))) return;
    const env = await this.elicit<string>({
      ask: 'select',
      message: 'Which environment?',
      options: ['staging', 'prod'],
    });
    await this.run(env);
  }
}

Primitive	What it does
await this.sample({ prompt })	Delegates LLM generation to the caller's model via MCP sampling
await this.confirm(question)	Yes/no prompt — returns boolean
await this.elicit(params)	Arbitrary input (text, select, form, file, etc.)
this.status(msg) / this.progress(v)	Live feedback during long work

Full reference: docs/reference/MCP-PRIMITIVES.md.

---

Remote Access: Claim Codes

By default every installed photon is visible to every connected MCP client. When you want to pair a remote agent with a subset of your photons — your phone driving Beam, a teammate reviewing one project, a CI agent scoped to a single directory — generate a claim code:

$ photon claim --scope /workspace/proj --ttl 4h --label "phone"
✓ Claim code: R3K-9QZ
  Scope:      /workspace/proj
  Expires in: 4h

The remote client presents the code as the Mcp-Claim-Code header on its MCP session. tools/list then only exposes photons whose source lives under that directory. Sessions without a code keep full access — the feature is strictly opt-in.

Full reference: docs/reference/CLAIM-CODES.md.

---

Marketplace

32 photons ready to install: databases, APIs, developer tools, and more.

photon search postgres
photon add postgres

You can also install directly from any GitHub repository using qualified refs:

photon add owner/repo/photon-name

Browse the full catalog in the official photons repository. You can also host a private marketplace for your team: internal tools that stay off the public internet.

---

Commands

# Run
photon                            # Open Beam UI
photon mcp <name>                 # Run as MCP server
photon mcp <name> --dev           # MCP server with hot reload
photon cli <name> [method]        # Run as CLI tool

# Install from GitHub
photon beam owner/repo/name       # Install & open in Beam
photon cli owner/repo/name method # Install & run via CLI

# Create
photon maker new <name>           # Scaffold a new photon

# Build
photon build <name>               # Compile to standalone binary
photon build <name> --with-app    # Include Beam UI in binary

# Manage
photon info                       # List all photons
photon info <name> --mcp          # Get MCP client config
photon maker validate <name>      # Check for errors

# Marketplace
photon add <name>                 # Install photon
photon search <query>             # Search marketplace
photon upgrade                    # Upgrade all

# Ops
photon doctor                     # Diagnose environment
photon test                       # Run tests
photon ps                         # Observe & control scheduled jobs, webhooks, sessions

Install from GitHub

Use qualified refs to install and run photons directly from any GitHub repository:

photon beam Arul-/photons/claw        # Install from GitHub, open in Beam
photon cli Arul-/photons/todo add     # Install from GitHub, run method

The format is owner/repo/photon-name. Transitive @photon dependencies from the same repo are resolved automatically.

Compile to Binary

Build standalone executables from any photon — no Node.js required on the target machine:

photon build my-tool                         # Binary for current platform
photon build my-tool -t bun-linux-x64        # Cross-compile for Linux
photon build my-tool --with-app              # Embed Beam UI as a desktop app

Uses Bun's compiler under the hood. The binary bundles the photon, its @dependencies, and transitive @photon deps into a single file.

---

Tag Reference

Tag	Where	What it does
@dependencies	Class	Auto-install npm packages on first run
@cli	Class	Declare system CLI dependencies, checked at load time
@format	Method	Result rendering (table, list, markdown, code, etc.)
@param ... {@choice a,b,c}	Param	Dropdown selection in Beam
@param ... {@choice-from method}	Param	Dynamic dropdown populated from another method's return value
@param ... {@format email}	Param	Input validation and field type
@param ... {@min N} {@max N}	Param	Numeric range constraints
@ui	Class/Method	Link a custom HTML template
@webhook	Method	Expose as HTTP endpoint
@scheduled	Method	Run on a cron schedule
@locked	Method	Distributed lock across processes
@autorun	Method	Auto-execute when selected in Beam
@mcp	Class	Inject another MCP server as a dependency
@icon	Class/Method	Set emoji icon

See the full Tag Reference for all 30+ tags with examples.

---

Documentation

Start here:

Guide
Getting Started	Install, build, and run your first photon in 5 minutes
Core Concepts	The 5 ideas behind Photon
Output Formats	Visual gallery of every @format type
Troubleshooting	Common issues and solutions

Go deeper:

Topic
Custom UI	Build rich interactive interfaces with the photon bridge API
OAuth	Built-in OAuth 2.0 with Google, GitHub, Microsoft
MCP Client Registration	Register MCP clients with Photon's AS via CIMD or DCR
Observability	OpenTelemetry traces, metrics, logs, and structured errors
Protocol Features	Capability handshake, structured errors, trace correlation
Daemon Pub/Sub	Real-time cross-process messaging
Webhooks	HTTP endpoints for external services
Locks	Distributed locks for exclusive access
Advanced Patterns	Lifecycle hooks, dependency injection, interactive workflows
Deployment	Docker, Cloudflare Workers, AWS Lambda, Systemd

Operate:

Topic
Security	Best practices and audit checklist
Marketplace Publishing	Create and share team marketplaces
Best Practices	Patterns for production photons

Reference: Complete Developer Guide · Tag Reference · Naming Conventions · Architecture · OAuth Authorization Server · Lifecycle & Ingress · PHOTON_DIR & Namespace · Changelog · Contributing

---

Open Source

Photon is free and open source under the MIT license.

The project is still evolving and contributions are welcome.

• Star the repository if the idea resonates
• Report issues
• Contribute improvements or examples