`force_extend_topology` does two jobs — stop a fresh IddCx monitor being CLONED onto the
existing panel, and serve as `restore_displays_ccd`'s last-resort "the desk is not left
dark" backstop. Probed directly on .173 with only the LG TV connected, its preset returns
rc=31 ERROR_GEN_FAILURE while SDC_USE_DATABASE_CURRENT returns 0, which reads like a
backstop that cannot back anything up.
On glass it is not, and this case is the measurement that settled it. Active paths went
1 -> (virtual up) 1 -> (after force-EXTEND) 2: with one connected display there is nothing
to extend across, hence rc=31; with the virtual present there are two and the preset
applies. Both real call sites run in exactly that state — the restore fires BEFORE the
REMOVE, so the virtual is still there. No defect. Recording it so nobody re-derives the
alarming half from the rc alone.
⭐ It also caught the clone hazard live: the arriving virtual monitor did NOT get its own
active path (1 -> 1); only the forced EXTEND gave it one (-> 2). That is exactly the
"no distinct source -> no frames" case the function's own doc describes, observed rather
than assumed.
⚠️ Residual, noted not asserted: a restore that fails once the virtual is already gone is
back to one connected display, where EXTEND returns 31 and cannot re-light anything.
Context for the sweep's other on-glass claims: the earlier `live_create_drop` and
`live_inplace_resize` passes on this box were taken with the TV POWERED OFF (every monitor
devnode Code 45), so they proved the driver round trip but never exercised deactivating a
real panel. Re-run now with the TV attached, `live_inplace_resize` still reports
in_place=true (target 257 -> 257, 2356x1332), so Phase 6.2 holds with a physical present.
Verified on .173: clippy -p punktfunk-host -p pf-vdisplay --all-targets and
-p pf-win-display --all-targets clean, 56 pass + 3 ignored, no orphans.
enricobuehler
2b2c6f045d