It does not work on a photograph, so nothing should offer it. `Segmentation`
is now one model pass and what it recognised: no region field, no merge
tree, no label upload, no granularity slider, and no readback of the whole
proxy to build a graph that collapses.
A click means "the object under the cursor". The region-selection path went
with the hierarchy it indexed — including the shift-click add/subtract,
which has no meaning for a whole object and would have been a modifier that
silently did nothing.
The passes, the hierarchy and the semantic prior stay in `dr-gpu` and
`dr-segment`, tested and documented. It is the *merge criterion* that
fails — the saddle is the minimum gradient along a boundary, so one weak
pixel merges two regions and real gradient noise puts a weak pixel on every
boundary. That is one function to replace, and the evidence for replacing it
is worth keeping. What is gone is the wiring, the option, and the control
that offered a user a choice with no outcome.
`MaskSource::Regions` remains in the pipeline: it is tested, it round-trips
through the sidecar, and a stored layer that names regions must still load
and be reported stale rather than failing to parse.
dtourolle
37f63edbf9