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Documentation / Diagon

Release notes

Last updated: 18 October 2026

What changed in each version of Diagon, newest first. Windows and AppImage installs update themselves; a .deb install needs the new package from the download page. Licensing & updates explains how updates arrive.

1.4.0

A layout update: diagrams come out tighter and symmetric, icons come in three sizes (bigger by default), and lines behave at the closer spacing.

The reason for all of it: a diagram that looks fine on a big monitor turned into confetti once a PowerPoint slide on a laptop shrank it to fit. Most of what the slide was shrinking was empty space.

Layout

  • Rows sit about one box-height apart (48 px; it was 88), and boxes within a row 24 px apart. A row grows only where something needs the room — an edge label between two rows, or a wide fan of children — so a long label in a left-to-right diagram is no longer cut off by the boxes at its ends, and a plain flowchart is 25-30 % shorter.
  • A parent now sits centred over its children and a chain stays straight. Before, every arranging pass shoved the lower half of a diagram a little further to one side, so a fan of children ended up beside its parent, chains became staircases, and the shipped architecture example had one long diagonal line across an empty region. That example is now 60 % narrower, and fitted to a laptop slide its labels are 9.5 px instead of 7.
  • Over the shipped examples the share of the drawing that is actually boxes went from 22 % to 31 %.

Boxes

  • Unconnected things inside a box form rows of a few — seven become 4 + 3, not a 3 × 3 grid with holes — and each row is as tall as its tallest member. In a left-to-right diagram they form columns the same way.
  • A box that holds a small flow plus loose children puts the loose ones in a block beside the flow instead of one long row across the top; this applies at every level, the diagram itself included.
  • A box is never narrower than its title or the labels on its own lines, and box frames lose a third of their air. A 67-node, 13-box architecture of the kind customers draw comes out half the size it was and twice as full.

Icons

  • Icons come in three sizes — small (32 px), medium (48 px) and large (64 px) — chosen in the text with one word, icon-size: on a line at the top for the whole diagram, inside a box for that box, or in a node's { … } for that node. The nearest setting wins; a number of pixels (16-96) also works. The language has the details.
  • A wrong icon-size value is an error with its line number, wherever it is written.
  • Medium (48 px) is the new default, so every diagram with icons gets icons 41 % bigger without changing anything. icon-size: small is close to the old size (32 px; it was 34). For a diagram that will go on a slide, icon-size: large on the first line.
  • An icon on a cylinder sits under the rim instead of across it. An assistant connected over MCP is told about the sizes and the rule for slides.

Lines

  • In a diagram without boxes, routing: orthogonal now goes around the other boxes; it used to draw straight through them.
  • Arrows leave by the bottom of a box and enter by the top (right and left in a left-to-right diagram). A hub with more lines than its bottom edge can hold hands the most sideways ones to its side edges, so arrowheads no longer merge.
  • A line through a gap runs down the middle instead of hugging a box, parallel lines sharing a gap are spread apart, and the small stair-steps where a line left a box are gone.
  • routing: curved in a diagram with boxes is a smooth rounded route that never cuts a box. It used to loop, double back and cross boxes — 26 lines through boxes in the customer-style architecture; now none.
  • A line never runs through a box's title, and an edge label never sits on a box.
  • A line keeps off box frames.
  • The careful routing costs time on very large boxed diagrams: one with 600 lines takes about 0.7 s to redraw instead of a tenth of a second. If a diagram is ever too large to route in time, the status bar says how many lines were left straight. A hub with very many lines can still have arrowheads that touch.

What changes for diagrams you already have

Every diagram gets tighter and moves. A box you pinned by hand (x:/y: in the text, or a drag) keeps its absolute spot while the automatic part shrinks around it, so it may look farther away than before — Auto-arrange once fixes that. A decision diamond now sits centred over its two outcomes, so a chain of decisions steps sideways a little instead of running dead straight. A very large diagram (dozens of boxes) is still too much for one laptop slide even at this spacing: its labels come out at about 3 px once the whole thing is fitted. Split it, or show it on a page you can zoom.

1.3.1

A maintenance update: a newer engine underneath, and updates that no longer close a window you were working in.

The engine

Diagon is built on Electron, which carries the Chromium browser engine. 1.3.1 moves it from Electron 43.0.0 to 43.7.9 — nineteen maintenance releases newer — and with it the security fixes made to Electron and Chromium since June. Diagon shows pictures fetched from the web (the icons in a diagram), and the part that does that should not be months behind on fixes. Your diagrams, files and settings are untouched.

On Linux this Electron has a known fault with the add-ons that KDE Plasma and some other desktops load into every program: it crashes at start-up where a global menu is used (Plasma's, and some Xfce, MATE and Budgie panels), and on any KDE Plasma desktop it crashes when the colour scheme changes while the program is open. Diagon works around both, so it starts and stays open there as 1.3.0 did — and from this version on, every Linux package is started on such a desktop, with the colour scheme changed under it, before it is released.

Updates

  • An update no longer closes another open Diagon window. On Windows, with Diagon open twice, quitting one installed the waiting update, and the installer closed the other window as well — unsaved work in it was lost. An update now installs only when Diagon is closed with no other Diagon window open, and Restart now says so instead of restarting. On a PC where Diagon is installed for all users, the same holds while Diagon runs in another signed-in account.
  • Restart now restarts quietly. On Windows it used to open the setup wizard. It now installs in the background and starts the new version. It warns first if the diagram has unsaved changes, and if the update cannot be started it says so and fetches it again.

Both are in 1.3.1 itself, so you will notice them from the next update on: 1.3.1 is still installed by the version you have now.

Smaller things

  • Windows names Soverain s.r.o. as the company in the program's properties and the list of installed apps (it said "Haustorius").
  • The user guide and the licence text in the Linux packages carried Windows line endings.

1.3.0

The built-in AI is gone. Your own assistant connects instead.

Up to 1.2.1, Diagon shipped with a small AI model inside the app and a ✨ Generate panel that turned a sentence into a diagram. In 1.3.0 that model, the panel and the button are removed. In their place, Diagon can be connected to the AI assistant you already use — Claude, Cursor, Copilot in VS Code, Codex and others — through the Model Context Protocol (MCP).

What you can do now

  • Ask your assistant, in its own chat, to draw or change a diagram, and it appears in your Diagon window.
  • The assistant learns Diagon's language from Diagon itself, has its text checked by Diagon's real parser, and can look at the finished picture and tidy it — or look at a draft without touching what's in your window.
  • An assistant's change is one Ctrl+Z away from undone, and nothing is saved until you save it.
  • Set it up in Help → Connect an AI assistant…. It's off until you switch it on, and it's included in the trial and in every subscription.

AI assistants has the setup for each assistant and the details.

Why

A model small enough to bundle and run on any laptop can only do so much, and it added about 1.6 GB to every download. So Diagon no longer ships one. If you use an AI assistant, Diagon now works with that; how well it draws depends on the assistant, not on Diagon.

What this changes for you

  • The download is about 100 MB (130 MB for the Linux AppImage) instead of about 2 GB, and the 8 GB memory recommendation is gone.
  • Diagon itself contains no AI and still sends your diagrams nowhere. The difference is on your assistant's side: what it reads from your diagram goes to its provider, under your agreement with them. With the old built-in model, that text never left your machine. If that matters for your diagrams, leave the connection switched off — everything else in Diagon works exactly as before.
  • If you used ✨ Generate, you now need an assistant of your own to get the same help. Diagon doesn't supply one.
  • If you never used it, nothing changes except the size.

If you subscribed for the built-in AI and this isn't what you want, write to hello@soverain.cz. A charge from the last 14 days is refunded in full on request, and the refund policy says what applies when Diagon no longer matches what we described.

Also in this version

  • Exports no longer cut off lines. SVG and PNG exports were cropped to the outermost boxes, so a loop, a line detouring around a pinned node, or a label on a long bend could be clipped. They're now cropped to everything that's drawn.
  • A web address written where a colour belongs is no longer fetched. A diagram could put an address in place of a colour (fill: url(…)), and Diagon would request it while drawing. Only real colours are applied now, whoever wrote the diagram.
  • A { on a line of its own froze the preview. A block with no name in front of it made the picture stop following the text, with no message. Diagon now says the block needs a name and draws the rest.
  • Help → Open full User Guide did nothing in an installed copy. It opens the guide now.
  • An icon that failed to download once stayed missing from exports until Diagon was restarted. It is tried again after a minute.
  • The icons example and the in-app guide pointed at an icon that no longer exists; both are fixed.

Earlier versions

Notes for 1.2.1 and earlier are on the releases page.