feat: stabilize face attachments and closed spline workflows

docs/book/src/guide/features.md

@@ -26,13 +26,23 @@ one undo step, including downstream parameter changes. Editing a placed componen
 edited feature before its downstream history. Cylindrical Emboss profile guides follow the
 sketch's chosen occurrence frame.
 
+New symmetric revolves split the entered angle evenly around the sketch profile, regardless
+of which way the selected axis points. Two Sides measures the second angle backward and the
+first angle forward along the sketch-normal sweep direction. Profiles on opposite sides of
+an axis each use their own sweep direction. Designs saved before format 11 keep their original
+angular placement when opened, edited or copied; creating another revolve uses the new behavior.
+To Object follows that same direction for each selected profile, including curved target faces.
+Pick a target away from the axis so its angular position is defined.
+
 For cylindrical **Emboss**, select a supported exterior cylinder face and a tangent sketch
 profile. **Deboss** cuts radially into the wall. Orthogonal line profiles, including holes and
 concave outlines, wrap with exact radial walls; the profile must stay clear of seams and ends.
 Complete cylinders and coaxial sleeves are supported. Capture pending component positions
 before applying. The feature stores the selected target and author occurrence paths, so edits
 and reopening retain the chosen instances. Other curved surfaces and free-form profiles remain
-unsupported; omitting the face retains the planar emboss behavior.
+unsupported. A new Emboss without an explicit face infers a unique eligible supported cylinder;
+select the face when the target is ambiguous. Older saved features without a face retain their
+planar placement.
 
 Fillets and chamfers handle straight edges between planar faces, whole smooth loops, runs of
 neighbouring edges with mitred or spherical corners, and closed chains of curved edges (a rolling
@@ -44,3 +54,7 @@ be found, the feature warns instead of silently picking another face.
 
 Press **Delete** on anything selected (bodies, faces, sketches, features, planes, components,
 canvases). It runs as one undoable step and lists the features that would go with it or fail.
+
+Face Extrude, face Revolve, and Press Pull retain linked generated profiles. When a modified planar face has no construction certificate, these internal profiles use the legacy named-face attachment and projection behavior so upstream edits still update the plane and outline. This compatibility path is private to those modeling tools: newly attached user sketches require a certified face or an explicitly fixed plane. Legacy internal attachments can follow the nearest matching face after topology changes; inspect their result after major upstream edits. Activate the intended occurrence before generating a face profile from a repeated component; capture a separately moved source position before creating a legacy profile across components.
+
+A negative Press Pull across a planar face containing a round through-hole can still fail when the Boolean cutter has coincident curved faces. This operation reports an error and preserves the design atomically; positive face extrusion and Press Pull retain the hole and remain linked.

docs/book/src/guide/sketching.md

@@ -25,9 +25,20 @@ error bound of 0.002 mm. Singular tangents, curvature cusps, possible self-inter
 excessive subdivisions are refused. Offset these curves individually: mixed chain junctions
 currently require separate geometry. `sketch.offset.break` releases an offset for independent
 editing, and undo restores its association. Older independently sampled offsets remain independent.
-Smooth open offsets can be offset again, including bounded refinement after a source edit.
-A closed offset uses a natural cubic spline whose seam can have different end tangents;
-offsetting that result again is refused when the seam has no unique normal.
+Smooth open and newly created smooth closed offsets can be offset again, including bounded
+refinement after a source edit. New closed outputs use a periodic cubic fit with continuous
+tangent and curvature at the seam. Break Offset Association preserves that interpolation,
+and its closing point remains joined when dragged. Deleting an output also removes its
+unused private fit points; deleting a source with a retained dependent is refused.
+
+For explicit closed fit splines, `sketch.spline.fit_point` accepts `periodic: true` and at
+least three distinct cyclic samples. It closes the loop automatically. Existing calls and
+older saved closed splines retain natural interpolation; older associative closed offsets
+also retain their saved natural fit. A legacy seam without a unique normal still refuses
+another offset. Periodic intent is stored on each curve and survives save, reopen and Break.
+While drawing a fit spline, click its starting point after three distinct samples to close
+it smoothly. Right-click finishes an ordinary natural fit. Offset accepts both ellipse
+handles and dense fitted curves; the second click sets the side and distance from the curve.
 
 Enable **3D Sketch** in the Sketch Palette to draw lines, fit splines and points off the plane.
 New 3D geometry follows its sketch's component placement, including the selected occurrence