Myrlin's Workbook

Open-source workspace manager for Claude Code - cost tracking, conflict detection, 4-pane embedded terminals, per-workspace docs & kanban, session templates, costs dashboard, 13 themes, and more. Discovers every session you've ever run, organizes them into workspaces. Runs in your browser, everything stays local.

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Quick Start

Try it now

npx myrlin-workbook          # Opens browser, discovers your real Claude sessions
npx myrlin-workbook --demo   # Opens browser with sample data (no real sessions needed)

Install from source

git clone https://github.com/therealarthur/myrlin-workbook.git
cd myrlin-workbook
npm install
npm run gui                   # Real sessions
npm run gui:demo              # Sample data

Password

On first launch, a random password is generated and saved to ~/.myrlin/config.json. This password persists across updates, reinstalls, and npx cache clears — you'll always use the same password.

To set your own:

# Option 1: Edit the config file (recommended — persists forever)
# ~/.myrlin/config.json → { "password": "your-password-here" }

# Option 2: Environment variable (overrides config, per-session)
CWM_PASSWORD=mypassword npx myrlin-workbook

Password lookup order: CWM_PASSWORD env var > ~/.myrlin/config.json > ./state/config.json > auto-generate.

Prerequisites

• Node.js 18+ (download)
• C++ Build Tools (required by node-pty for real terminal emulation):
  • Windows: Visual Studio Build Tools with "Desktop development with C++" workload
  • macOS: xcode-select --install
  • Linux: sudo apt install build-essential python3

npm install fails? You're missing the C++ build tools above. See Troubleshooting.

Run Modes

Command	Description
npx myrlin-workbook	Web GUI via npx
npm run gui	Web GUI (localhost:3456)
npm run gui:demo	Web GUI with sample data
npm start	TUI mode (terminal-only, blessed)
npm run demo	TUI with sample data

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Why

I use Claude Code daily and had a growing list of pet peeves. Can't name sessions, so /resume is just picking from a list of IDs. No shift+enter for multiline. If you have a few sessions going at once, the terminal window juggling gets old fast. PC restarts and you have to reopen everything from scratch. No idea what you're spending.

Got fed up and built something for it. Myrlin scans ~/.claude/projects/, finds every session you've ever run, and you organize them into workspaces with embedded terminals, docs, and cost tracking. Everything runs locally, no cloud, no telemetry.

Compared to other tools

There are good tools in this space. I tried them. Here's where Myrlin fits:

Feature	Myrlin	ClaudeCodeUI	Opcode	Claude Squad
Cost tracking	Yes	No	Yes	No
Costs dashboard	Yes	No	Yes	No
Session discovery	Yes	Yes	No	No
Session manager overlay	Yes	No	No	No
Workspace docs/kanban	Yes	No	No	No
Themes	13 (Catppuccin, Nord, Dracula, etc.)	No	No	No
Session templates	Yes	No	No	No
Conflict detection	Yes	No	No	No
Embedded terminals	4-pane grid	Single	No	No
Tab grouping	Yes	No	No	No
Windows native	Yes	Buggy	Yes (desktop)	No (tmux)
TUI mode	Yes	No	No	No
Multi-agent	Claude only	Claude+Cursor+Codex	Claude only	5+ tools
File explorer	No	Yes	No	No
npx install	Yes	Yes	No	No
Build step required	None	Vite	Tauri	None

What those tools do better: ClaudeCodeUI has a file explorer and multi-agent support. Opcode is a polished desktop app with 20k stars. Claude Squad supports 5+ AI tools. Myrlin is workspace-first with cost tracking and per-workspace docs. Different approach to the same problem.

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Features

Cost Tracking

Per-session and per-workspace cost breakdown. Parses Claude's JSONL usage data, applies model-aware pricing (Opus, Sonnet, Haiku), shows input/output/cache tokens. Know exactly what you're spending.

Session Discovery

• Scans ~/.claude/projects/ and finds all existing Claude sessions
• Shows project directory, session count, size, last active
• Auto-titles sessions from conversation content
• Import sessions into workspaces with one click

Workspaces & Sessions

• Named workspaces with color coding
• Group workspaces under umbrella folders
• Drag-and-drop sessions between workspaces and into terminal panes
• State persists to disk. Survives crashes and restarts
• Auto-recovery on startup (detects orphaned sessions, restores state)

Embedded Terminals

• 4-pane terminal grid (xterm.js + node-pty + WebSocket). Real PTY, not fake.
• Tab groups: named sets of terminal panes ("Research", "Debug"), switchable and persistent
• PTY sessions survive page refresh with scrollback replay on reconnect
• Model selection (Opus, Sonnet, Haiku) and session resume
• Right-click context menu with Copy, Stop, Restart, Model picker

Per-Workspace Docs & Feature Board

• Notes, Goals, Tasks, Rules, and Roadmap sections per workspace
• Kanban-style feature board (Planned -> Active -> Review -> Done)
• Markdown editor with formatting toolbar
• AI Insights tab: auto-generated summaries of workspace sessions

Session Templates

Save your common launch configurations. Pre-set working directory, model, flags, and spawn options. One click to launch a new session from a template.

Conflict Detection

Real-time warnings when two or more running sessions are editing the same files. Runs git status across active sessions and cross-references modified files. Prevents you from stepping on your own work.

Quick Switcher

Ctrl+K / Cmd+K opens a fuzzy search across all sessions and workspaces. Jump to anything instantly.

Git & Worktree Management

• Full git status per workspace: current branch, dirty/clean, ahead/behind remote
• Branch listing and worktree CRUD
• "New Feature Session": right-click a workspace -> creates a branch + worktree + Claude session in one click
• Branch badges on session rows

Themes

13 themes organized into Dark and Light sections. 4 official Catppuccin (Mocha, Macchiato, Frappe, Latte), 3 community favorites (Nord, Dracula, Tokyo Night), 4 custom flavors (Cherry, Ocean, Amber, Mint), and 2 light alternatives (Rose Pine Dawn, Gruvbox Light). Toggle from the header dropdown. Choice persists in localStorage.

Port Detection & Resource Monitoring

• Automatic port detection for running sessions (PowerShell on Windows, lsof on Unix)
• Per-session CPU and memory tracking
• System overview (CPU, RAM, uptime)
• Stop, restart, or kill sessions from the Resources tab

Mobile

   

• Responsive layout with bottom tab bar
• Touch gestures: swipe between terminal panes, edge swipe for sidebar, long-press for context menus
• Mobile terminal toolbar: keyboard toggle, Enter, Tab, Ctrl+C, Ctrl+D, Esc, arrows, Copy, Upload
• Keyboard-aware viewport resizing (terminal stays visible above soft keyboard)

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Full Feature List

A comprehensive list of everything Myrlin Workbook offers today.

Core

• Session discovery - scans ~/.claude/projects/, finds every session you've ever run
• Workspace management - named workspaces with color coding, drag-and-drop grouping
• Auto-recovery - restores state after crash or restart, detects orphaned sessions
• State persistence - JSON on disk, survives everything

Terminals

• 4-pane terminal grid - xterm.js + node-pty + WebSocket, real PTY (not fake)
• Tab groups - named sets of panes ("Research", "Debug"), switchable and persistent
• Tab close buttons - with live session kill confirmation dialog
• Drag-and-hold tab grouping - hold 1.2s over another tab to create a folder
• Cross-tab terminal pane dragging - drag sessions between panes freely
• PTY sessions survive page refresh - scrollback replay on reconnect
• Model selection - Opus, Sonnet, Haiku per terminal
• Right-click context menu - Copy, Stop, Restart, Model picker
• Bracketed paste mode - proper paste handling in terminal sessions

Cost Tracking

• Per-session and per-workspace cost breakdown - input/output/cache tokens
• Costs dashboard tab - period selector (Day / Week / Month / All)
• SVG timeline chart - visual spend over time, model breakdown
• Sortable session table - rank sessions by cost, tokens, or duration
• Parses JSONL usage data - model-aware pricing (Opus, Sonnet, Haiku)

Session Management

• Session manager overlay - click header stats to open, full session control
• Mass selection and batch stop - select multiple sessions, stop them all at once
• Filter - All / Running / Stopped quick filters
• One-click terminal open - from session manager rows
• Session templates - save launch configs (directory, model, flags), one-click launch
• Quick switcher - Ctrl+K / Cmd+K fuzzy search across sessions and workspaces

Docs & Planning

• Per-workspace docs - Notes, Goals, Tasks, Rules, Roadmap sections
• Kanban-style feature board - Planned, Active, Review, Done columns
• Markdown editor - with formatting toolbar
• AI Insights tab - auto-generated summaries of workspace sessions

Conflict Detection

• Real-time file conflict warnings - detects when two+ sessions edit the same files
• Conflict center UI - per-file breakdown with session attribution
• Click session chips - jump directly to the terminal pane for that session

Git & Worktree

• Git status per workspace - current branch, dirty/clean, ahead/behind remote
• Branch listing and worktree CRUD - create, switch, delete from the UI
• "New Feature Session" - creates branch + worktree + Claude session in one click
• Branch badges - shown on session rows

Themes

• 13 themes - 4 Catppuccin (Mocha, Macchiato, Frappe, Latte) + Nord, Dracula, Tokyo Night + Cherry, Ocean, Amber, Mint + Rose Pine Dawn, Gruvbox Light
• Header dropdown toggle - choice persists in localStorage

Resources & Monitoring

• Port detection - automatic discovery for running sessions (PowerShell on Windows, lsof on Unix)
• Per-session CPU and memory - live tracking
• System overview - CPU, RAM, uptime
• Stop / restart / kill - from the Resources tab

Mobile

• Responsive layout - bottom tab bar on small screens
• Touch gestures - swipe between panes, edge swipe for sidebar, long-press for context menus
• Mobile terminal toolbar - keyboard toggle, Enter, Tab, Ctrl+C, Ctrl+D, Esc, arrows, Copy, Upload
• Keyboard-aware viewport - terminal stays visible above soft keyboard

... more to come.

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Remote Access

Expose your local instance with a Cloudflare tunnel:

npm run gui                                      # Start the server
cloudflared tunnel --url http://localhost:3456    # In another terminal

Open the URL from any device. All WebSocket terminal connections, SSE streams, and REST API calls route through the tunnel. For a stable URL, see Cloudflare tunnel docs.

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Architecture

Browser (vanilla JS SPA)
  |
  |-- REST API ---------- Express server
  |                         |-- State store (JSON + EventEmitter)
  |                         |-- Session manager (launch/stop/restart)
  |                         |-- Resource monitoring (CPU, RAM, per-PID)
  |                         +-- Workspace groups, discovery, docs
  |
  |-- SSE --------------- Real-time updates (store events -> clients)
  |
  +-- WebSocket --------- Terminal I/O (binary frames)
                             +-- node-pty -> ConPTY / PTY

No React, no build step. Vanilla JS SPA, Express backend. ~24 source files, 26 tests.

Project Structure

src/
|-- state/
|   |-- store.js              # Core state (JSON persistence + EventEmitter)
|   +-- docs-manager.js       # Per-workspace markdown docs
|-- core/
|   |-- session-manager.js    # Launch/stop/restart processes
|   |-- workspace-manager.js  # Workspace CRUD
|   |-- process-tracker.js    # PID monitoring
|   |-- recovery.js           # Auto-recovery on startup
|   +-- notifications.js      # Event-based notifications
|-- web/
|   |-- server.js             # Express API + SSE + resources
|   |-- auth.js               # Token auth + rate limiting
|   |-- pty-manager.js        # PTY session lifecycle
|   +-- public/
|       |-- index.html        # SPA shell
|       |-- app.js            # Frontend application
|       |-- styles.css        # Catppuccin themes
|       +-- terminal.js       # TerminalPane (xterm.js + WebSocket)
|-- ui/                       # TUI mode (blessed)
|-- index.js                  # TUI entry point
+-- gui.js                    # GUI entry point

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Configuration

Password

Loaded in order:

1. CWM_PASSWORD environment variable
2. state/config.json -> { "password": "..." }
3. Auto-generated (printed to console, saved to config)

Port

Default 3456. Override with PORT:

PORT=8080 npm run gui

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Keyboard Shortcuts

Key	Action
Ctrl+K / Cmd+K	Quick switcher
Escape	Close modals / menus
Ctrl+Enter	Save in notes editor
Double-click session	Inline rename
Right-click session	Context menu (launch, model, rename, hide)
Right-click workspace	Context menu (docs, add session, edit, delete)

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Troubleshooting

npm install fails with node-gyp errors

node-pty needs C++ build tools to compile native bindings. Install the tools listed in Prerequisites.

Windows quick fix:

npm install -g windows-build-tools

npx myrlin-workbook hangs on install

Same issue. node-pty is compiling. If it fails, install the C++ build tools first, then try again.

Still stuck? Open an issue with your full error output and OS version.

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Roadmap

• Multi-provider support (Codex, Cursor, Aider)
• Conflict center shipped
• Session manager overlay shipped
• Costs dashboard shipped
• Tab grouping shipped
• Session templates shipped
• Session search shipped
• Light theme shipped (4 Catppuccin themes)
• Cost tracking shipped (per-session token + cost breakdown)
• Feature board shipped (Kanban per workspace)
• Git worktree management shipped (branch CRUD, "New Feature Session" flow)
• Port detection shipped (auto-discover ports from running sessions)
• Export/import workspaces
• Pinned sessions
• Push notifications for session events

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License

AGPL-3.0. Use, modify, self-host freely. If you run a modified version as a public service, you must publish source. See LICENSE.

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Contributing

Issues and PRs welcome. No build step. Clone, npm install, hack.

npm test        # 26 tests
npm run gui     # Start dev server

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Built by Arthur.