Tapesmith

Label studio for the Phomemo P12 (and P12 Pro), with a built in MCP server for AI assistants.

Tapesmith is a Windows application for the Phomemo P12 Bluetooth label printer (12 mm tape). It replaces the phone app with a fast local print service, a browser based editor, a template gallery, a command line, a REST API, an MCP server (Claude Code, Claude Desktop and other MCP clients) and optional integrations for home labs and home automation. Everything runs on your own PC; nothing is sent to a cloud service.

Screenshots

Templates with a live preview	Label editor
Template gallery	Print history with reprint
Log viewer	Dark mode

All screenshots use made up demo data and are produced by tools/readme_shots.py. The full set (German and English, light and dark, desktop and phone) is in docs/screenshots.

Features

• Quick print from the browser, the tray icon or a global hotkey (Ctrl+Alt+L), with automatic text fitting and a live preview at real size.
• Editor with text, QR codes, Code128, DataMatrix, icons, shapes and images, multiple tabs, undo, autosave and crash recovery.
• Templates with more than 30 built in designs (pantry, freezer, storage boxes, office, network and power labels, cable flags, grid strips for patch panels and fuse boxes) and your own templates as JSON files. The preview fills empty fields with example content, so you always see the label before you type, and printing unlocks once the required fields are filled.
• Series printing from CSV, Excel or the clipboard, numbering ranges and counters.
• Print service that owns the printer connection: queue with automatic retry, print history, statistics, tape roll tracking and misprint protection. If the printer does not answer, Reconnect in the status dialog rebuilds the Bluetooth connection with a longer wait.
• Everything in the browser: all settings, including tokens and passwords for integrations, and a log viewer with level filter, search, live view and download. The tray icon only opens browser tabs and shows the running version.
• Command line (tapesmith, short alias p12) for scripts, plus a PowerShell module.
• MCP server for AI assistants, over stdio (tapesmith mcp, setup snippet with tapesmith mcp --config) or Streamable HTTP (/mcp, off by default). An assistant always renders a preview first and prints only after you confirm it.
• Accessibility and languages: keyboard operation, screen reader labels, high contrast, dark mode. English and German throughout: web interface, tray, print service messages, built in templates and command line follow the Windows display language (any language other than German gives English), or the setting app.language; TAPESMITH_LANG=en forces a language for the CLI.
• Installation through Python without admin rights and signed automatic updates with hash pinned packages and rollback.

Optional modules

Everything beyond the core app is a built in module that is off until you turn it on under Settings > Modules (or tapesmith module enable <id>). Modules that are off appear nowhere in the interface. Available: Inventory (boxes, contents, lending), Drives (drives of this PC, SSH disk scanner and ZFS disk replacement assistant), Proxmox VE (VM and container labels), Paperless-ngx (ASN and warranty labels), Home Assistant (battery and maintenance labels), Obsidian vault via MCP, Assets with short links (deploy/shortlink), NetBox cable import, classifieds and a serial number scan from a photo. Tapesmith ships without any preset addresses or tokens. Also part of the core app: MQTT discovery for Home Assistant, Telegram notifications, a hot folder and an MCP server for AI assistants. Setup notes: docs/manual.md (English), docs/handbuch.md (German) and deploy/.

Installation

Tapesmith is distributed as a Python package on PyPI and runs with the signed Python from python.org. It has no executable of its own, so Windows Smart App Control does not block it, although Tapesmith itself carries no code signing certificate.

1. Install Python 3.12 (3.11 works too), for example with winget in a normal terminal (no admin rights needed):

   winget install Python.Python.3.12
   

2. Install Tapesmith for the current user and set it up:

   py -m pip install --user tapesmith
   py -m tapesmith install
   

   tapesmith install creates %LOCALAPPDATA%\Programs\Tapesmith with one Python environment per version (versions\<version>, the junction current points to the active one), a start menu entry "Tapesmith", an entry under Installed apps (with uninstall), the tapesmith:// and p12label:// links, the Explorer context menu and the autostart of the tray icon. Everything starts as pythonw.exe -m tapesmith... from the active environment. No admin rights are needed. Useful options: --no-autostart, --no-start, --status (show the state, change nothing).

3. Pair the printer in Windows Bluetooth settings, then pick it in the web interface under Settings (or run py -m tapesmith setup).

Connection tips: the P12 talks to Tapesmith over the Bluetooth serial port (for example COM3). Windows lists it as "Driver unavailable"; that is expected, no printer driver is needed, and the connection opens by itself whenever Tapesmith prints. If the status shows the printer as unreachable: switch it on (it turns itself off after a while), disconnect the phone app (the P12 accepts one connection at a time) and click Reconnect in the status dialog.

Your settings and history live in %APPDATA%\Tapesmith. Installing, updating and uninstalling never touch them.

Updates: after you agree (the web interface asks once), Tapesmith checks the GitHub releases of this project. A new version is installed into a new environment next to the running one: the signed release manifest lists every package with its SHA-256, pip installs only wheels with a matching checksum (pip install --require-hashes --only-binary=:all:), the self test of the new version must pass, and Tapesmith switches over while idle, with automatic rollback if the new version does not start. Manually: Settings > Updates, or py -m tapesmith update check and py -m tapesmith update install. You can also pick any published version (0.4.0 and later), newer or older, under Settings > Updates > Specific version, or with py -m tapesmith update list and py -m tapesmith update install <version>. Going back to an older version is only done on your explicit request, after a confirmation and an automatic backup of your data.

Uninstall: Settings > Apps > Installed apps > Tapesmith, the start menu entry "Tapesmith deinstallieren", or py -m tapesmith uninstall. This removes the program folder, start menu entries, autostart, links and the entry under Installed apps; your data in %APPDATA%\Tapesmith stays. To also remove the package that was used for the setup: py -m pip uninstall tapesmith.

Smart App Control: Windows 11 may block programs without a code signature. Tapesmith therefore never ships an executable: python.exe and pythonw.exe from python.org are signed, and all native parts come as unmodified wheels of their upstream projects from PyPI. The small .exe launchers that pip creates for command line entry points are not used by the installed app; if Smart App Control blocks them, use py -m tapesmith ... instead of tapesmith ....

Upgrading from the portable build (0.3 and older) or a source checkout: run the two commands of step 2. tapesmith install stops the old Tapesmith, takes over the installation folder, replaces autostart, start menu entry and uninstall entry, and removes the old Tapesmith.exe. An autostart that points to a Python environment of a source checkout is replaced as well. Your data stays as it is.

Upgrading from "P12 Label" (0.2.x): on first start Tapesmith copies %APPDATA%\P12Label to %APPDATA%\Tapesmith once (the old folder stays as a backup), and the installer removes the program files, start menu entry, autostart and uninstall entry of the old installation. Links using p12label:// keep working as an alias of tapesmith://; old P12LABEL_* environment variables still work as a fallback for TAPESMITH_*.

Security

• The print service listens on 127.0.0.1 only. Access from your LAN is opt in (lan.enabled), limited to configured private networks and always requires an API token (roles: admin, print, family). Tokens are stored as SHA-256 hashes only.
• Host and Origin headers are checked (DNS rebinding protection), failed logins are rate limited.
• Secrets never go into configuration files. Tokens and passwords are entered in the web interface (Settings > Tokens and passwords) and stored in the Windows Credential Manager; the API never sends them back. Settings only hold a reference such as keyring:tapesmith/mqtt. References to file:<path> or env:<NAME> keep working and can be moved into the Credential Manager with one click ("Take over into Tapesmith").
• Log files never contain tokens or passwords, and the log viewer masks them as well.
• Updates are only installed if the manifest carries a valid Ed25519 signature from a key listed in src/tapesmith/update/trusted_keys.json, and pip installs only wheels whose SHA-256 is listed in that manifest.
• AI assistants print over MCP only after a preview and an explicit confirm=true; the preview is single use, expires after 15 minutes and must still match the rendered label.
• The automatic update check is off until you agree: the web interface asks once on the first start of the installed app (Settings > Updates changes it later).

Known limits (plain text session token in your user profile, plain HTTP in LAN mode, trust path of the first installation) and hardening tips are in SECURITY.md. Please report vulnerabilities as described in SECURITY.md.

Release signing and privacy

Tapesmith has no code signing certificate and ships no executable of its own (see Installation). Releases are built by GitHub Actions from this repository, published to PyPI with Trusted Publishing, and every update manifest is signed with an Ed25519 key; the app installs only packages whose SHA-256 is listed in a correctly signed manifest.

• Committers and reviewers: the project maintainer (owner of github.com/essendyx/tapesmith)
• Approvers: the project maintainer (owner of github.com/essendyx/tapesmith)

Privacy: This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it. Which connections Tapesmith makes and how releases are built and signed: CODE_SIGNING_POLICY.md.

Development

Requirements: Windows 10 or 11, Python 3.11 or newer, Node.js 20 or newer (only to build the web UI).

python -m venv .venv
.venv\Scripts\pip install -e .[dev]
.venv\Scripts\python -m pytest -q
cd web && npm ci && npm run check
python tools\build_web.py          # builds the web UI into src/tapesmith/webui/static
python -m build                     # wheel and sdist in dist/

Tests never print, never open real COM ports, Bluetooth or network services and never touch your real data folder (they run with TAPESMITH_HOME set to a temporary folder). Hardware tests are marked @pytest.mark.hardware and only run with --hardware. See CONTRIBUTING.md.

Documentation: user manual in English docs/manual.md and German docs/handbuch.md, hardware and protocol findings docs/hardware/README.md, operations notes deploy/infra/README.md. Translations: web/src/locales/, src/tapesmith/locales/ and the message catalog src/tapesmith/locales/messages/en.json (maintained with python tools/i18n_messages.py).

License

Tapesmith is released under the MIT License. Third party components and their licenses are listed in THIRD_PARTY_NOTICES.md.

Acknowledgements

The P12 print protocol was first documented by the phomemo-p12-tools project (MIT License, Copyright (c) 2022 Timo "polskafan" Dobbrick, packaged by TOKITA Hiroshi). Tapesmith keeps a byte compatible reference stream in its tests and offers the old phomemo_render_label and phomemo_print_p12 commands for compatibility. Icons come from Tabler Icons (MIT) and Simple Icons (CC0); label fonts are DejaVu.

Tapesmith is an independent project and not affiliated with Phomemo.