Keep the master refresh separate from the V3-to-V4 lossless-conversion and
checkpoint JSON fixes so the release baseline and each feature change remain
independently reviewable. This checkpoint extends the already-published
4435f6f519 merge before the #4583 child is rebased.
Integrate exactly master 5ec3ffe337062ab5bb4955933008afe8d0a0b915. Its #4156
changes add watched file/document refresh, filesystem watch readiness,
directory expansion restoration, and chat bottom-follow fixes. They update
shared filesystem and Client consumers without changing Session format or
snapshot generation.
The merge has no conflicts. Its 114-file scope and line counts match upstream;
code and prose additions/removals are unchanged. Only the two translation
pairing records incorporate the release branch's retained V4 documentation.
Validation: 762 owner tests passed (1 platform skip), 11 focused Web tests
passed, full build passed, and all 41 doc-sync checks passed. Runtime closure
and Client package checks passed; fs-local publint completed with the existing
source-wildcard export warning.
Tianyi Cui
87f0df0550