When a newer wallet build embeds a newer daemon, extractEmbeddedResources()
detects the size change and tries to overwrite dragonxd.exe in the daemon dir —
but the write is a plain truncating ofstream, which fails silently if the file
is locked. A running (or just-killed, handle-not-yet-released) daemon locks the
.exe on Windows (and Linux returns ETXTBSY), so the stale binary was kept and
the wallet kept launching the old daemon version.
If the direct write fails, move the stale binary aside to "<name>.old" (renaming
a running/locked executable is permitted on both Windows and Linux — the running
process keeps the moved copy) and write the fresh one at the original path. A
best-effort pass removes leftover .old files once the old process has exited.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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