Update 0.3.0 — undo, a world you can resize, and a speed dial that finally works

Three things you could not do before this update: take back a click, change the size of the world, and set how fast the simulation actually runs. All three are here — plus the language learned to ask the simulation about itself.

Ctrl+Z

• Undo with Ctrl+Z, redo with Ctrl+Shift+Z. Deleted a branch, a method or a cell kind by a stray click? Take it back. Every edit to the world (kinds, constants, property slots) and to your rule or program goes into the history.
• Fifty steps deep, on any project. Even the QR-code example — a program with thousands of nested nodes — costs about 35 KB per step, so the whole history fits in a couple of megabytes.
• Painting on the grid is deliberately left out of the history: the mouse is a brush, not an edit, and you would not want one Ctrl+Z to undo a hundred strokes.

The world is not 160×100 any more

• Type a new size in the SYSTEM panel — Grid W and Grid H are editable fields now. The grid is moved into the new size on the spot, anchored at the bottom-left corner: whatever no longer fits is cut off, new space starts empty. No restart, no reload.
• Pick the size a new project starts with on the PLAY screen — from 40×40 for something you want to see up close, to 500×300 for a pattern that needs room. The choice is remembered between runs.
• A saved project keeps its own size in its file, so sharing a 300×200 world just works.
• Worth knowing: every cell runs your program every tick, so 500×300 is nine times the work of 160×100. It runs — just slower.

Simulation speed, in ticks per second

The old speed control counted ticks per frame, which meant the real speed depended on your monitor: the same setting ran nearly twice as fast on a 144 Hz screen as on a 60 Hz one. That is gone.

• A speed field sits next to START/STOP and is measured in ticks per second. Type a value, or nudge it with ↑/↓ — the step grows with the number, so you are not clicking sixty times to get from 60 to 600.
• The speed is saved with your project and comes back the next time you open it.
• Settings now hold the default speed for new projects, a switch for starting the simulation automatically when a project opens, and a flag for whether a project's own speed may be loaded at all — turn it off and every project runs at your speed, not its author's.
• Opening someone else's fast project asks first. A file saved above 300 ticks per second offers three answers: run it at your standard speed, run it at its own, or don't open it. No more accidentally launching a project that pins your machine.
• The SYSTEM panel shows both the speed you asked for and the speed you are actually getting. When they drift apart, the automaton is heavier than the time it has — that is the honest signal that you are hitting a limit.

When a tick doesn't finish

There has always been a safety limit on how much work one tick may do, so a runaway loop cannot freeze the app. Until now hitting it looked like nothing at all — the grid simply froze half-updated, with no explanation.

• A badge now appears in the corner of the field: the program did not fit into one tick, how many cells out of how many were updated before the budget ran out, and what is usually to blame — a REPEAT with no way out, or a DISTANCE searching the whole grid.

New in the language

• SYSTEM — a new node that hands your program the parameters of the simulation itself: FPS (the configured speed), TICK (which generation you are on), GRID W / GRID H (the size of the world) and CELL PX (how big a cell is on screen). Counting ticks by hand in a cell property is no longer a thing, and a program can finally adapt to the size of the world it lives in. Left-click the parameter to pick from the list, right-click to cycle.
• BREAK — leave the nearest loop. It punches through nested IFs but stops at the loop, so it is not a sneaky RETURN.
• REPEAT-IF — a loop that runs while a condition holds, instead of a fixed number of times. Same safety ceiling as REPEAT.

New example: Radar

A rotating radar sweep over expanding range rings, with a fading trail and yellow contacts that flash as the beam passes over them. Paint your own contacts with the default brush and watch the sweep find them.

It is also a live demonstration of everything above:

• Change the speed while it runs — from 5 to 200 ticks per second. The sweep gets smoother or choppier, but it does not get faster: one revolution takes exactly TurnSec seconds either way, because the program counts time in seconds through SYSTEM.FPS.
• Resize the world while it runs — the radar recentres itself on the next tick, because it asks SYSTEM.GRID W/H instead of assuming.
• Ring spacing is set in screen pixels and divided by SYSTEM.CELL PX, so the rings stay the same width to the eye no matter the window or the grid.
• The beam itself is a loop that steps outward from the centre and quits with BREAK the moment it leaves the grid — nobody can know in advance how many steps that takes.

Five constants to play with while it turns: seconds per revolution, seconds per ring, ring spacing, how long the trail glows, and the step of the beam.

Settings, rearranged

• The settings screen is now a list of rows — name on the left, control on the right — instead of a column of wide buttons. What is switched on and what it is set to reads at a glance.

Fixes

• A broken number no longer loses your project. If a value in a cell property or a constant ever became infinite or not-a-number, saving failed outright with json: unsupported value: -Inf and the file was not written at all. Such values are now saved as zero and the app tells you it happened — losing one broken number beats losing the whole project.
• The tick counter resets for every project. It used to carry over from whatever you had open before.
• Long option descriptions in Settings no longer run underneath the controls next to them.

Projects saved with earlier versions open exactly as before — a file without a speed of its own simply uses yours.