2.0.0-beta.31: Hydration mismatch when using nested conditionals in <Show when>

[dangkyokhoang]

Describe the bug

This pattern causes hydration mismatch:

function Badge(props: { required?: boolean; optional?: boolean }) {
  return (
    <Show
      when={props.required ? 'Required' : props.optional ? 'Optional' : null}
    >
      {(text) => <span>{text()}</span>}
    </Show>
  );
}

Your Example Website or App

https://stackblitz.com/edit/nitrojs-nitro-x1i4tv9d?file=src%2Fapp.tsx

Steps to Reproduce the Bug or Issue

1. Go to the link above
2. See console logs

Expected behavior

No issue

Screenshots or Videos

No response

Platform

• OS: [e.g. macOS, Windows, Linux]
• Browser: [e.g. Chrome, Safari, Firefox]
• Version: [e.g. 91.1]

Additional context

Related: #2959

[ryansolid]

Fixed on next in dc7b5c2 — and the root cause turned out to be runtime-side, not the compiler.

Root cause. A compiled conditional prop like when={props.required ? 'Required' : props.optional ? 'Optional' : null} allocates a condition memo (_$memo(() => !!cond)) every time the getter is evaluated, as a child of whichever node is reading. That's fine when both runtimes evaluate the getter under id-matched owners — which holds for user components (same code runs on both sides) and for content holes (matched scope owners). But the server flow controls are separate implementations from their client twins, and they compensated for the client's internal memo slots with bare id burns while evaluating the getters themselves under a different internal node:

• Show (your repro): the client reads when inside its conditionValue memo (child slot 0); the server read it inside its single value memo (slot 2, after two burns). The getter's memo landed in different id spaces, drifting every id allocated after it — hence the unclaimed <span>.
• Switch: each Match's when is read inside per-match conditionValue memos on the client, but inside the value memo on the server.
• For/Repeat: the each/count getter was evaluated in the same child space used to synthesize row ids, so an allocating getter also shifted every row id by one.

Fix. The server twins now evaluate each allocation-capable getter inside a real node at the same child slot as the client (Show mirrors conditionValue; Switch mirrors switchFunc with per-match conditionValue memos; mapArray/repeat put the row id space in its own owner at slot 0 with the reading memo at slot 1). A bare id burn is now only used for slots whose compute never evaluates a prop getter. Dynamic and boundary fallback getters were audited and were already aligned. Compiler output is unchanged.

Parity-harness scenarios covering Show (dynamic + static), Switch, For, and Loading-fallback ternaries all pass, including your exact Badge repro. Ships in the next beta.