fix(expand): distinguish part blockers from plate edges

docs/geometry/expand-spacing.md

@@ -2,6 +2,6 @@
 
 `Plate > Expand Spacing` moves selected parts by translation only. The first selected part is the anchor for selected pairs; the later selected member moves, and nonselected parts remain fixed. The plate retains its own `EdgeSpacing` floor; the command does not change `PartSpacing` or `EdgeSpacing`.
 
-Every selected/selected and selected/nonselected pair has an operation-entry clearance floor, measured against material with cutouts subtracted. A later move may reuse slack opened by an earlier move, but it cannot reduce a pair below its own starting gap. Existing overlaps are accepted for attempted separation; a remaining overlap is reported as a violation, not a successful positive gap. Temporarily blocked pairs are retried after another part moves, while a pass without positive movement stops the relaxation.
+Every selected/selected and selected/nonselected pair has an operation-entry clearance floor, measured against material with cutouts subtracted. A later move may reuse slack opened by an earlier move, but it cannot reduce a pair below its own starting gap. Existing overlaps are accepted for attempted separation; a remaining overlap is reported as a violation, not a successful positive gap. Temporarily blocked pairs are retried after another part moves, while a pass without positive movement stops the relaxation. An individual violation's `BlockedByEdge` flag is true only when the work-area edge is the first limiting cause; the desktop status currently displays a blocked-pair count, not those individual causes.
 
 Probes run on scratch poses. Each trial translation is clipped against blocking material along its entire straight path, including cutout walls. Initially overlapping convex line profiles can take a certified direct exit; unsupported or ambiguous overlap paths stay put and remain reported. When a part touches a cutout wall and the usual nearest-boundary direction makes no safe progress, the tool tries the opposite direction through the same checks. Tiny clamp keep-outs use a conservative native-bound motion limit when tolerant geometry cannot certify them. Cancellation before application leaves the live layout unchanged; `Separate` never changes it. The desktop command is synchronous and has no Cancel dialog or automatic save. A bounded search reports the spacing it found, not an optimum. See `docs/geometry/directional-slides.md` for directional contact behavior.