The renderMessages() re-anchor call `queueMicrotask(()=>_reanchorPinnedTailAfterRender(...))`
threw `ReferenceError: _reanchorPinnedTailAfterRender is not defined` in the standalone
renderMessages() node harness (test_anchor_fallback_ownership), which evals the extracted
renderMessages body with only a minimal set of stubbed helpers.
Guard the call with `typeof` checks on both `queueMicrotask` and
`_reanchorPinnedTailAfterRender`, mirroring the existing
`if(typeof _deferClearProgrammaticScroll==='function')` guard a couple of lines below, so
a harness that evals renderMessages without defining these helpers does not throw. In the
browser both are always defined, so the fix path is unchanged.
Add a source-lock asserting the guard so a future refactor can't drop it and re-break the
harness.
allenliang2022
496f369304
