feat: hit on primitives

client/world/primitive.go

@@ -1,28 +1,32 @@
 package world
 
-import (
-	"github.com/google/uuid"
-)
+// PrimitiveID is a compact stable identifier for primitives stored in the World.
+// It is allocated by the World and may be reused after deletion (free-list).
+type PrimitiveID uint32
 
 // MapItem is the common interface implemented by all world primitives.
 type MapItem interface {
-	ID() uuid.UUID
+	ID() PrimitiveID
 }
 
 // Point is a point primitive in fixed-point world coordinates.
 type Point struct {
-	Id   uuid.UUID
+	Id   PrimitiveID
 	X, Y int
 
 	// Priority controls per-object draw ordering. Smaller draws earlier.
 	Priority int
 	// StyleID references a resolved style in the world's style table.
 	StyleID StyleID
+
+	// HitSlopPx expands hit-test radius in screen pixels (per-object override).
+	// 0 means "use primitive default".
+	HitSlopPx int
 }
 
 // Line is a line segment primitive in fixed-point world coordinates.
 type Line struct {
-	Id     uuid.UUID
+	Id     PrimitiveID
 	X1, Y1 int
 	X2, Y2 int
 
@@ -30,28 +34,36 @@ type Line struct {
 	Priority int
 	// StyleID references a resolved style in the world's style table.
 	StyleID StyleID
+
+	// HitSlopPx expands hit-test radius in screen pixels (per-object override).
+	// 0 means "use primitive default".
+	HitSlopPx int
 }
 
 // Circle is a circle primitive in fixed-point world coordinates.
 type Circle struct {
-	Id     uuid.UUID
+	Id     PrimitiveID
 	X, Y   int
 	Radius int
+
 	// Priority controls per-object draw ordering. Smaller draws earlier.
 	Priority int
-
 	// StyleID references a resolved style in the world's style table.
 	StyleID StyleID
+
+	// HitSlopPx expands hit-test radius in screen pixels (per-object override).
+	// 0 means "use primitive default".
+	HitSlopPx int
 }
 
 // ID returns the point identifier.
-func (p Point) ID() uuid.UUID { return p.Id }
+func (p Point) ID() PrimitiveID { return p.Id }
 
 // ID returns the line identifier.
-func (l Line) ID() uuid.UUID { return l.Id }
+func (l Line) ID() PrimitiveID { return l.Id }
 
 // ID returns the circle identifier.
-func (c Circle) ID() uuid.UUID { return c.Id }
+func (c Circle) ID() PrimitiveID { return c.Id }
 
 // MinX returns the minimum X endpoint coordinate of the line.
 func (l Line) MinX() int { return min(l.X1, l.X2) }