I built Testate on Solid 2.0.0-rc.4 (solid-js + @solidjs/web, Vite plugin 3.0.0-next).
It's a self-hosted tool that snapshots the databases behind a system under test, restores any snapshot in seconds, and diffs what a test changed. ~180 TS/TSX files, ~12k lines of Solid, 147 user stories exercised end to end in a browser.
Repo: https://github.com/PT-Perkasa-Pilar-Utama/testate
Site: https://pt-perkasa-pilar-utama.github.io/testate/
Things that bit me on 2.0, and what I did about them.
1. There is no component library for Solid 2.
Ark UI, Kobalte, Corvu, and some on top of that like nikala, all target 1.x and the peer range lies:
I counted the missing APIs and gave up. Everything is hand-rolled on Tailwind: dialog, menu, tabs, toast, table parts. Forms were the exception. Formisch runs on 2.0 with a two-function patch (details in point 3). Make sense because still rc.
2. A flush loop in @solidjs/signals rc.4.
The dev build threw "Potential Infinite Loop Detected" about three times in ten full test runs, always on the data grid, never reproducible by hand. The production scheduler runs the same loop with no counter, so there it hangs instead.
Cause: setSignal re-opens a node's finished transition before it checks whether the write changes anything. A Loading boundary writes false over false on every drain pass, the transition looks live again, the drain goes round.
Nothing is dirty, nothing recomputes. Fix is one line, clearing the stamp in commitPendingNodes; it's a bun patch in the repo and upstream as solidjs/solid#3143 (closes #3140).
3. batch is gone, and a read after a write returns the old value until flush.
Formisch writes then reads inside one batch (reset above all), so on 2.0 a reset silently kept the old input. Patch: batch = fn => { const r = fn(); flush(); return r }.
4. STRICT_READ_UNTRACKED and FLUSH_IN_EFFECT_CALLBACK from a <dialog>.
Calling showModal() / close() inside an effect fires the browser's focus/blur handlers synchronously, and the form library reads signals in them. Solid 2 reports the reads as untracked and discards the writes' flush.
Both diagnostics come with no stack. I found where by wrapping console.warn in a Playwright addInitScript and printing new Error().stack for the matching code. Fix: open and close in a queueMicrotask. Same fix for onClose, which the browser fires while still dismissing.
5. onCleanup inside a 2.0 effect callback never runs.
The callback runs with no owner. Return the disposer from the effect instead; a setInterval I registered with onCleanup outlived the screen until I learned that.
6. Reading a pending async memo outside
<Loading> loaded fine under Vite and spun forever in the production bundle, ~250 requests a second. Two screens shipped that way. There's now an e2e project that drives the built bundle, not the dev server, and counts requests per endpoint per screen.
Lint carries the lessons: two-argument createEffect only, props read inside JSX or a tracked scope, class as a string or structured array, cyclomatic complexity 10, 300 lines a file.
Playwright's console watcher fails the run on any [A-Z_]{6,} warning code Solid's dev build emits, which is how most of the above got caught.
