A category mask showed nothing and its adjustment covered the whole
photograph. Both from one line: the loop in `MaskPass::rasterise` picks a
distance field by matching `layer.source`, that match named only `Subject`,
and a `Category` layer fell through to `_ => (&self.empty_subject, 0)` — a
1x1 placeholder. No field, so nothing to draw and nothing to confine the
adjustment.
The comment three lines above the arm I missed describes the failure I then
shipped:
an absent mask that defaults to "everything" would apply the
adjustment to the whole photograph
There are *two* matches on `layer.source` in that loop — one choosing the
field, one building the params. Adding the category to the second and not
the first compiles, runs, and is wrong in exactly the way the first one
warns about.
## Also: a missing mask must still be the right size
Both model-backed arms of `ensure_subject_fields` used `unwrap_or_default`,
which yields an empty `Vec` when the coverage is gone. `SubjectMasks::upload`
rejects a wrong-sized field and fails the whole batch, so `self.subjects`
becomes `None` and *every* layer in the stack loses its mask — one stale
reference silently unmasking the others.
Pre-existing, and it mattered less when the only model-backed source was a
subject: an instance index goes missing rarely. A category name goes missing
whenever the descriptor is edited, which is a thing the descriptor exists to
allow. A full-size empty field costs one layer instead of all of them.
Neither of these is reachable from a test on this machine — both live past a
GPU adapter and a real segmentation — so they surfaced the only way they
could, by someone opening the app and looking.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
dtourolleandClaude Opus 5
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