Trial Is Live

Last time I solemnly announced my “fairly simple yet no less brilliant” idea — trial access via Telegram bot. Then wrote the bot itself. And then spent a good while thinking about how to make the whole thing work without crutches and unnecessary dependencies — no database, no state files, nothing at all.

Sat down. Thought it through. Implemented it.

Telling myself “done” — that’s a rare and sweet feeling.

How the BOT Works #

An unregistered user sends the bot /trial — and a few seconds later receives:

• A VLESS link to connect to the Sigil Gate network
• A QR code — to scan with a phone when setting up another device
• A “Copy link” button — because manually selecting a 300-character string is already a clinical condition

The link lives for one hour. After that, the device is deactivated. The user gets ten such attempts. After that, the bot politely hints that it might be time to register.

The Clever Bit Inside #

What I like most is how the limit is tracked — without a single extra table. All state is encoded directly in the device name.

Each trial device is named {telegram_id}{digit} — and the digit at the end is the remaining limit. The first device for a user with ID 123456789 gets the name 1234567899. The next one — 1234567898. Once we hit zero — the limit is exhausted. The bot can check the state at any moment with a single query to the registry — it searches for devices by prefix and looks at the minimum digit. The registry is the only “database”.

Things like this bring disproportionately large satisfaction relative to their technical complexity.

Cleaning Up After Itself #

An hour passes — the device needs to be deactivated and removed from Entry nodes. On the Core node, a systemd timer runs a cleanup script every hour. It finds all expired trial devices — using file mtime in the registry, since the created field only stores the date without time — deactivates them and removes them from the nodes. It also prunes archived records, keeping only the one needed for the counter.

The bot doesn’t wait for the timer either: on every /trial call, it lazily checks the user’s active devices and sends expired ones to deactivation in the background.

QR Code. Just a QR Code. #

I have to stop on this separately.

When I was adding the “Copy link” button, the thought flashed: “A QR code would be an absolute luxury.” The luxury took about fifteen minutes to implement. The qrcode library does everything on its own, and aiogram can accept an image directly from an in-memory buffer — no file on disk needed. Scan with your phone — you’re connected. It’s so convenient that I’m now a little embarrassed I didn’t do it from the start.

Yes, we’ve brought another dependency into the project. But it was worth it.

Now we have a convenient interface that lets any user — even an unregistered one — connect to the Sigil Gate network and get access to the open internet.