The plan asked what to draw when a symbol in lane mode holds overlapping
children, and offered to report it as a decision waiting for a person. Wrong
question: they never overlap. Placement claims time — anything placed, moved
or grown over occupied time trims, removes or splits what it lands on — so the
operation that could have made an overlap did not, and `span/finish`, which is
already the single commit path and already refuses rather than half-applying,
is where that is enforced. An overlap is then a bug in a command and not a
state to design around.
The check stays, named `symbol/overlaps` and used three ways: the commit path
refuses one, a property test asserts no command can produce one, and a
document that somehow holds one still LOADS and is drawn visibly wrong with
the status saying so. Not `problems`, which stops a document loading, and not
`conflicts`, which means somebody has a decision to make — a display hint must
never be able to keep a document from opening.
The one place a person can ask for the impossible is toggling lane mode on
over children that already overlap. That refuses and offers to trim them into
a sequence, through the `:required-frames` retry the model already uses.
Also written down, because it is the pair the modifier exists to separate:
a plain body drag is temporal and replaces, trimming extents as needed; shift
is structural and goes through `nest/move-node` into the symbol under the
pointer, which has to keep working for symbols held in a lane.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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