Sketch commands return the ids of the points, curves, constraints and dimensions they create as created: {points, curves, constraints, dimensions}, worked out in Session::execute from the sketch before and after, so a script can dimension and constrain new geometry right away; ids stay stable and are not reused after a delete (undo rewinds the counters with the design). The MCP execute tool describes the field

docs/book/src/guide/sketching.md

@@ -15,6 +15,11 @@ fillet, chamfer, offset (O), mirror, patterns, move/copy and scale.
 **Project** (P) and **Intersect** bring model edges into the sketch as linked geometry that
 follows later changes. Sketching on a face projects its edges automatically.
 
+Run from a script or the control channel, every command that adds sketch geometry returns the
+ids of what it added (`created: {points, curves, constraints, dimensions}`). Ids are stable and
+never reused within a sketch, even after a delete, so a script can dimension or constrain the new
+geometry right away.
+
 ## Constraints and dimensions
 
 The solver is SolveCraft's own (damped Gauss–Newton with degree-of-freedom analysis). Constraints: