KSeF Plugin

Name: ksef

Description: Send and receive KSeF (Polish National e-Invoice System) invoices via the ksef CLI, with guided onboarding: install from npm, token setup, login

Author: Flop (flopspm@gmail.com)

Version: 0.1.1

Keywords: ksef, e-invoice, faktura, poland, invoice, cli, fa3, upo

The KSeF plugin teaches Claude Code to operate the ksef command-line tool (npm package ksef-client-ts) — a client for the Polish National e-Invoice System (KSeF). It is aimed at regular users, not developers: the skill focuses on the two everyday jobs — sending invoices and finding/downloading them — and includes a guided, conversational onboarding that installs the tool from npm, explains what a KSeF token is and how to generate it in the government portal, asks for the NIP and token, saves them locally, and logs in. Production environment by default.

Installation

claude plugin install ksef@flugins

Important: After installing the plugin, restart Claude Code to activate skills.

Tip: Enable auto-update via /plugin → Installed → select the plugin → enable auto-update.

Requirements

• Node.js 18+ (the onboarding installs the CLI itself via npm install -g ksef-client-ts)
• Your company's NIP and a KSeF token (generated once in the KSeF web portal — the onboarding explains where and how)

Features

Skill

• ksef — activates automatically when you ask to send, find, or download KSeF invoices, download UPO receipts, set up KSeF, or debug KSeF errors. You can also invoke it manually by typing /ksef (with no task, it checks setup and asks what you want to do).

Onboarding

On first use (no CLI installed or not logged in) the skill switches to a guided onboarding: install → what a token is and how to generate it in the portal → enter NIP + token → login → verification. Every step is explained in plain language, and Claude performs the technical actions (installing, saving the token, logging in) itself. The token is entered in the chat once for simplicity; the final step tells the user exactly where it was saved, that it appeared in the chat history, and how to rotate it if they want a clean one.

Usage

Type /ksef for an explicit start, or just ask in natural language, e.g.:

• "Wyślij tę fakturę do KSeF" / "Send this invoice to KSeF"
• "Find my KSeF invoices since June and download the latest one"
• "Why am I getting error 440 from KSeF?"

The skill checks auth state (auth whoami), runs onboarding if needed, and then performs the send/receive flow on the production environment (sandbox only on explicit request).

What the skill knows that --help won't tell you

• The CLI reads no environment variables — everything goes through flags or ~/.ksef/config.json, and the default environment is prod
• Nested --help (e.g. ksef invoice send --help) is broken and prints the root help — the skill ships a full flag-level reference for all 16 command groups (docs/reference.md)
• Session auto-recovery cascade, invoice-number uniqueness (error 440), batch vs online sessions, and known discrepancies between the CLI and the project's own docs

Configuration

No install-time configuration. On first use the skill asks for your NIP and KSeF token in the chat, saves the token to ~/.ksef/token.txt and logs in (the CLI then keeps its own session and credentials in ~/.ksef/, permissions 600). This favors simplicity over secrecy: the token is typed into the conversation, so it lands in the chat history — the onboarding tells you this and how to rotate the token if you'd rather not keep one that touched the chat.