The size+mtime check from 094273df5 is unreliable on filesystems with
coarse mtime resolution: a same-length rewrite within the same tick
(e.g. "a" → "b") leaves both fields unchanged and falsely trips the
"file content did not change on disk" guard. CI on ubuntu Bun 1.3.14
hit this in the create-then-update aggregation test.
Re-read the file post-write and compare bytes to the previous content
instead — deterministic regardless of FS timestamp granularity.
can1357
d03f1e0c79