PLN: "part of the migration also: no d7 when d6 is free. d7 often was sefcond
melo, should be a d6 now d6 ids not a shitty mapped knob, but a proper column
like others".

That is the history exactly. d6's knob used to be somewhere useless, so a
second melody went to d7 and d6 was left empty; since the column remap every
one of d4-d8 owns a fader, a B knob and a C knob, so the reason is gone and
only the habit remains. A set with a hole at d6 wastes a whole column.

150 moves in 133 files. `d7 -> d6` is most of it; a lone melody with both
slots free compacts to d5.

THE BAND IS {5, 6, 7} AND IT IS DERIVED, NOT DECREED. An orbit number decides
which family DJ filter and which family mute the part answers to. From the
authored grid, d5/d6/d7 share both maps, so a move between them changes
nothing about the sound — while d4 is the bass (gF2) and d8 is percussion
(gF1/gM2), so compacting into or out of those would silently re-assign which
filter sweeps the part and which button drops it. The tool computes the band by
asking lcxl_grid which orbits agree with d6 on both families, so if the grid
ever changes, the band follows instead of rotting.

It refuses rather than guesses: 7 orbits carry an explicit `# orbit N`, which
overrides the output orbit independently of the `dN` name, so renaming the
declaration alone would move the pattern's identity and leave its AUDIO behind.
Comments are never rewritten — a commented `-- d7 $ …` is an alternative to
re-enable mid-set. Bus slots (`crushbus 71`) and `cut` groups stay put: a bus
id is an audio-graph edit and a cut group is a choke group, not an orbit.

VERIFIED: re-plan reports 0 moves left. silent-eval --seeded re-run over all
703 files and diffed per-file against the pre-migration baseline — zero verdict
changes, 703/703 joined. And the declaration multiset of every one of the 133
files is a pure permutation inside the band, with nothing outside it touched:
no pattern was dropped and no orbit was declared twice where it was not
already. That last check exists because a naive compaction fusing two blocks'
melodies onto one orbit would be silent, not loud — the later declaration wins.