Dogfooding #3: CoSy Tests reva-fork --- Bug Reports, Fixed or Filed

Saw #16 introduced reva-fork, my port of the Reva Forth to Rust and WebAssembly, and CoSy, an APL-like language, running on top of it. Since then reva-fork has had a release almost every day, and CoSy has become the way I validate the public repository: real code, written for Reva well before my port existed.

Then detailed bug documentation arrived. Today’s work is mostly cleanup, and regression tests for every reported issue.

Resource	Link
reva-fork	softwarewrighter/reva-fork
Live demos	Reva in the browser (2026.1107.0, GitHub Pages), CoSy in the browser (2026.1106.2, on my staging site: not GitHub Pages, since the port is still private and its licensing unclear)
CoSy	cosy.com, its Forth code
The CoSy port	private for now
Earlier	Saw #16: Reva Forth, Ported to Rust and WebAssembly, and CoSy on Top
The series	Dogfooding: every post
Comments	Discord

A release a day

Version	What it added
2026.1101.0	The IUP virtual library and one text UI for the browser, desktop and terminal; the notebook; help with real documentation
2026.1101.1	IUP dialogs and the notebook full screen in a terminal; undo, redo and autosave; turtle drawings saved as files; Upload in the browser
2026.1102.0	“Reva Fork” branding; saved images everywhere; the Reva 7.0 layer; --port-check; errors with FILE:LINE; the runaway-loop guard
2026.1103.0	The version in one VERSION file; a rebuilt web site never runs stale files
2026.1104.0	Pasted lines run one at a time in the web REPL; a notebook in its own file; a fix for the web demo’s text UI
2026.1105.0	ms waits in the browser and the desktop app, so animations draw frame by frame
2026.1106.0	Graphics for IUP programs: CD canvases and timers in the browser and the desktop app; diagnostics that name the word at fault
2026.1106.1	README and docs brought up to date, with a canvas demo on the live site (needs ui/cd-demo cd-demo) and a new docs/diagnostics.md
2026.1106.2	A release is checked everywhere before it ships: just release-check builds and checks the CLI, the web page, reva-serve and the desktop app

Errors that say where

CoSy is a substantial body of Forth, so when something goes wrong, the first useful answer is where. Errors now name the file and line, and the file that included it:

inner.f:3 (from outer.f:3): ERROR: unknown word: ...

Faults report the word that was running and the stack, and since today they name the callers too, innermost first:

(in a+0xc <- b <- c, eip ...)

Today’s releases add opt-in checks for the harder cases, each with a CLI flag and a ?diagnose= page option:

• --underflow fail-at-word stops in the word that underflowed, even when a later push hides it: : f1 drop drop ; : f2 f1 1 ; then 1 f2 stops in f1+0xa <- f2.
• --check-execute stops an execute of something that is not code, naming who executed it, where 0 execute used to fault at address 0.
• --trace-compile shows each word compiled into a definition, and which words compiled it.

Two more make long sessions safer. A stack underflow warns once and carries on, as Reva did, with --underflow fail for the old behavior. And a loop that runs for five seconds without asking for input pauses in the browser and the desktop app, with Stop, five seconds more, or keep going; in the terminal, --max-cpu SECONDS ends it.

Existing code, unchanged

needs compat/reva70 loads a Reva 7.0 compatibility layer, so CoSy’s Job.f and Tui.f open their window without edits. For code written on Windows, reva --port-check finds drive letters, backslash paths, Windows shell commands and .bat files, and reports each as FILE:LINE:COL; --fix DIR writes migrated copies and never touches the originals.

A better web REPL

Pasted lines run one at a time, files can be uploaded and then included, a missing file says so, and a rebuilt site never runs stale files. ms now waits in the browser, so an animation like this draws one tree at a time:

: trees 13 2 do i tree-demo 1000 ms loop ;

SQLite works the same way in the terminal, the desktop app and the browser.

The bug catalog

A dramatization of the "first actual case of bug being found": the moth in the Harvard Mark II's relay, 1947.

The catalog has 26 entries, drawn from CoSy’s logs from 2015 to 2019. Each one was reproduced, where it could be, and given an owner: the CoSy port, reva-fork, or CoSy’s own source.

Outcome	Entries
Works, or fixed	11
Open, in CoSy’s own source	3
Not recreatable (the words were renamed or removed)	6
Unknown	4
By design (Forth comments do not nest)	1

The three open ones are in CoSy’s across and allocate, outside the port, and each has a documented workaround. Today’s 14 golden tests pin every entry that can be run, and the three open ones are marked to fail on purpose: when a fix lands, the test says so.

How CoSy feeds reva-fork

The CoSy port never changes reva-fork directly. When it finds a problem, it reproduces it, decides who owns it, and files an ask against reva-fork: symptom, reproduction, workaround, suggested fix and priority. reva-fork takes the ask as a step in its own plan, and when the fix ships, the CoSy side drops its workaround and closes the ask. Twenty-two asks so far, and most are done; the four diagnostics above were ask 22, finished today.

The tests grew along the way: reva-fork’s golden tests from 31 to 60, and CoSy’s to 39.

Next

I’m winding down work on reva-fork and CoSy for a while. Several other X_eTaL projects are ramping up: ray tracing on the CPU and GPU, and machine learning, with fine-tuning and manifolds. I’m also working on some Hackaday hardware projects, with FPGAs and analog circuits.

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[Ed. 2026/11/07: reva-fork 2026.1107.0 adds an ls word and makes pp work without a needs line; gives the default notebook more to show (words, help, files and libraries); adds a tour (docs/tour.md) and an IUP/CD guide (docs/iup.md); and fixes a tail-call miscompile, in which about 1 in 256 quotations ending in a call jumped a byte into the word it called. The live demo link above now names that release (2080152; post history).]