4d9f1059 rescued these two scripts from $HOME, where they had been living
un-versioned, and committed them without the exec bit. The symlinks in
~/.local/bin resolved fine to a file systemd then refused to run:

  Process: ExecStart=/home/pln/.local/bin/tidal-ardour-autoroute.sh
           (code=exited, status=203/EXEC)
  Active: activating (auto-restart)

An auto-restarting unit reads as busy rather than broken, which is why
rig_units reported 'activating' and nobody chased it. Net effect: the autoroute
that puts twelve orbits onto Ardour's Tidal NN tracks has not run since 23 Aug
— the exact regression 4d9f1059 was written to end.

The recurrence has a cause, and it is repo config: core.fileMode = false here,
so git ignores exec-bit changes from the working tree entirely. That is why
4e0d63ae already had to fix the mirror image of this (+x on disk, 644 in the
index), and why chmod can never be the whole fix in THIS repo — it silently
does nothing as far as the index is concerned. `git update-index --chmod=+x`
is the tool that works.

Both halves done: chmod for this checkout, update-index for the index, so a
fresh clone is born runnable.