Sheet metal rims and holes, plastic features, lofts, raised pieces and merged walls take face attachments (#677)

Sheet metal rims and bend ends attach by name (<panel>:rim.<edge>, <flange>:rim.bend0/1), as do face profiles from sheet faces. A plain or counterbored Hole square to a panel is machined into the flat pattern. Boss, Lip, Rest and Snap Fit keep the body's history and name their own faces. Hole tools name their faces by the part they cut, and pattern copies as copies. A pattern's repeated fillets keep the body's history. Loft sides are named by their section curves. A piece Offset Face moved off its face's plane attaches by its own qualified name. Sides of a profile grown to overlap a flush body keep their sketch line's name, so walls a Join merged take a sketch (#681). Face sketch 75% -> 90%, offset plane 75% -> 90%, press-pull/extrude 64% -> 85% in the action matrix; baseline blessed.

Fixes #494, fixes #495, fixes #560, fixes #561, fixes #563, fixes #564, fixes #681.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/face-attachments.md

@@ -29,16 +29,29 @@ carry their seed's construction certificate, so a sketch attached to the seed be
 patterned keeps resolving to the seed: of the faces carrying one certificate, the producing
 feature's own face is the one whose name is not a copy's.
 
-Faces whose history is not exact (Offset Face, the plastic features, sheet metal rims, faces a
-feature rebuilt without reporting its history), ambiguous sources, and the pieces of a face
-split on purpose with Split Face (each piece is its own face) require an explicit fixed plane
-instead. The error says why, and the Create Sketch dialog then offers **Use fixed plane**,
+Where the pieces of one name no longer share a plane (Offset Face raised one piece of a top a
+cut had split), each piece is attached by its own name: the face's, qualified by the faces
+around it (`F2:top#[F2:side:l4,F4:side:l4]`). The plastic features (Boss, Lip, Rest, Snap Fit)
+keep the history of the body they go on and name their own faces by the part they make
+(`F4:post:top`, `F5:rest:side:0`, `F6:arm:top`), so those take attachments too. A side an extrude grew to
+overlap a flush body before joining it (its neighbours lengthened past the sketch's corners) is
+still named by the sketch line it runs along, so a wall a Join merged from two extrudes' walls
+attaches by the first one's name and answers to the other's.
+
+Faces whose history is not exact (faces a feature rebuilt without reporting its history),
+ambiguous sources, and the pieces of a face split on purpose with Split Face (each piece is its
+own face) require an explicit fixed plane instead. The error says why, and the Create Sketch dialog then offers **Use fixed plane**,
 which places the sketch on that face's current plane without following later changes. A
 nearby or parallel face is never used to repair a new attachment automatically.
 
 The flat faces of a sheet metal body are the exception: they have no construction
 certificate, so a sketch on one attaches to its panel by name (`sheet:<body>:<panel>:<side>`)
-and finds it again after every rebuild, unfold and refold. If that panel no longer exists the
+and finds it again after every rebuild, unfold and refold. The rims (the sheet's thickness
+along a panel's straight edge) attach the same way, by the edge they run along
+(`<panel>:rim.l3` for a base sketch line, `<flange>:rim.far`, `rim.side0`, `rim.side1`), and so
+do the flat ends of a bend (`<flange>:rim.bend0`, `rim.bend1`); a rim's plane faces out of the
+panel, its x along the edge and its y across the thickness. Extrude and Press Pull from a sheet
+face use the same attachment. If that panel no longer exists the
 sketch reports a lost attachment, as above. See the sheet metal guide.
 
 ## Create and repair