feat: Add ports on group elements

Groups now accept ports/ports-margins like blocks. Port name labels
default to outside the group border (outside-port-names: true) so they
don't overlap child elements; set to false for block-style inside
labels.

doc/examples.typ

@@ -188,6 +188,45 @@ wire.wire("w2", ("b2-port-out", "b3-port-in2"),
           style: "zigzag")
 ```)
 
+#let group-ports = example(```
+// outside-port-names: true (default) — labels outside the border
+element.group(
+  id: "g1", name: "outside (default)",
+  stroke: (dash: "dashed"),
+  fill: util.colors.blue.lighten(60%),
+  padding: 2em,
+  outside-port-names: true,
+  ports: (
+    west:  ((id: "in",  name: "D"),),
+    east:  ((id: "out", name: "Q"),),
+  ),
+  { element.block(id: "b1", w: 2, h: 1.5, x: 0, y: 0,
+      fill: util.colors.green,
+      ports: (west: ((id: "d", name: "d"),),
+              east: ((id: "q", name: "q"),))) }
+)
+wire.wire("wG1in",  ("g1-port-in", "b1-port-d"), directed: true)
+wire.wire("wG1out", ("b1-port-q",  "g1-port-out"), directed: true)
+
+// outside-port-names: false — labels inside the border (block style)
+element.group(
+  id: "g2", name: "inside",
+  stroke: (dash: "dashed"),
+  fill: util.colors.orange.lighten(60%),
+  padding: 2em,
+  outside-port-names: false,
+  ports: (
+    west:  ((id: "in",  name: "D"),),
+    east:  ((id: "out", name: "Q"),),
+  ),
+  { element.block(id: "b2", w: 2, h: 1.5, x: 6, y: 0,
+      fill: util.colors.green,
+      ports: (west: ((id: "d"),), east: ((id: "q"),))) }
+)
+wire.stub("g2-port-in",  "west")
+wire.stub("g2-port-out", "east")
+```, vertical: true)
+
 #let intersection = example(```
 wire.wire("w1", ((0, 0), (1, 1)), style: "zigzag")
 wire.wire("w2", ((0, 0), (1, -.5)),

gallery/test_group_ports.typ

@@ -0,0 +1,84 @@
+// Demonstrates ports on a group element.
+// outside-port-names: true  (default) — labels outside the group border
+// outside-port-names: false           — labels inside  (block-style)
+#import "/src/lib.typ": circuit, element, util, wire
+
+#set page(width: auto, height: auto, margin: .5cm)
+
+#circuit({
+  // --- Group with port labels OUTSIDE (default) ---
+  element.group(
+    id: "cpu",
+    name: "CPU (labels outside)",
+    name-anchor: "north",
+    stroke: (dash: "dashed"),
+    fill: util.colors.yellow.lighten(60%),
+    padding: 1em,
+    outside-port-names: true,
+    ports: (
+      west: (
+        (id: "in1", name: "D1"),
+        (id: "in2", name: "D2"),
+      ),
+      east: ((id: "out", name: "Q"),),
+      south: (
+        (id: "rst", name: "RST", vertical: true),
+        (id: "done", name: "DONE", vertical: true),
+      ),
+    ),
+    {
+      element.block(
+        id: "reg2",
+        w: 2.5,
+        h: 3,
+        x: 0,
+        y: 0,
+        fill: util.colors.green,
+        ports: (
+          west: ((id: "d1"), (id: "d2")),
+          east: ((id: "q"),),
+          north: ((id: "clk", clock: true),),
+        ),
+      )
+    },
+  )
+  // --- Group with port labels INSIDE (outside-port-names: false) ---
+  element.group(
+    id: "cpu2",
+    name: "CPU (labels inside)",
+    name-anchor: "north",
+    stroke: (dash: "dashed"),
+    fill: util.colors.yellow.lighten(60%),
+    padding: 4em,
+    outside-port-names: false,
+    ports: (
+      west: (
+        (id: "in1", name: "D1"),
+        (id: "in2", name: "D2"),
+      ),
+      east: ((id: "out", name: "Q"),),
+      south: (
+        (id: "rst", name: "RST", vertical: true),
+        (id: "done", name: "DONE", vertical: true),
+      ),
+    ),
+    {
+      element.block(
+        id: "reg2",
+        w: 2.5,
+        h: 3,
+        x: 10,
+        y: 0,
+        fill: util.colors.green,
+        ports: (
+          west: ((id: "d1"), (id: "d2")),
+          east: ((id: "q"),),
+          north: ((id: "clk", clock: true),),
+        ),
+      )
+    },
+  )
+  wire.stub("cpu2-port-in1", "west", name: "A")
+  wire.stub("cpu2-port-in2", "west", name: "B")
+  wire.stub("cpu2-port-out", "east", name: "Q")
+})

src/elements/group.typ

@@ -1,9 +1,15 @@
 #import "/src/cetz.typ": draw, coordinate
 #import "../util.typ"
+#import "ports.typ": add-ports
 
 /// Draws a group of elements
 ///
 /// #examples.group
+///
+/// Ports can also be defined on a group, just like on a block. By default
+/// port labels are drawn *outside* the group border so they do not overlap
+/// child elements. Set `outside-port-names: false` to draw them inside.
+/// #examples.group-ports
 /// - body (elements, function): Elements to group
 /// - id (str): see #doc-ref("element.elmt")
 /// - name (str): The group's name
@@ -16,6 +22,10 @@
 ///    - array: either (`<all>`,), (`<vertical>`, `<horizontal>`) or (`<top>`, `<right>`, `<bottom>`, `<left>`)
 ///    - dictionary: valid keys are "top", "right", "bottom" and "left"
 /// - radius (number): The corner radius
+/// - ports (dictionary): see #doc-ref("element.elmt")
+/// - ports-margins (dictionary): see #doc-ref("element.elmt")
+/// - outside-port-names (bool): If `true` (default), port name labels are drawn outside the group border so they do not overlap child elements. Set to `false` to draw labels inside, matching the block behaviour
+/// - debug (dictionary): see #doc-ref("element.elmt")
 #let group(
   body,
   id: "",
@@ -24,7 +34,13 @@
   fill: none,
   stroke: black + 1pt,
   padding: 0.5em,
-  radius: 0.5em
+  radius: 0.5em,
+  ports: (:),
+  ports-margins: (:),
+  outside-port-names: true,
+  debug: (
+    ports: false
+  )
 ) = {
   let min-x = none
   let max-x = none
@@ -68,6 +84,19 @@
     stroke: stroke,
     fill: fill
   )
+
+  add-ports(
+    id,
+    id + ".north-west",
+    id + ".north-east",
+    id + ".south-east",
+    id + ".south-west",
+    ports,
+    ports-margins,
+    debug: debug.ports,
+    outside-name: outside-port-names,
+  )
+
   if name != none {
     draw.content(
       id + "." + name-anchor,

src/elements/ports.typ

@@ -1,11 +1,12 @@
 #import "/src/cetz.typ": draw
-#import "../util.typ": rotate-anchor
+#import "../util.typ": rotate-anchor, opposite-anchor
 
 #let add-port(
   elmt-id, side, port, pos,
   prev: none,
   next: none,
-  debug: false
+  debug: false,
+  outside-name: false,
 ) = {
   let name = port.at("name", default: "")
   let name-rotate = port.at("vertical", default: false)
@@ -27,9 +28,21 @@
     // TODO: use context or vectors to have the height relative to the width
     draw.line(prev, pos1, next)
   }
+
+  // When outside-name is true (e.g. for groups) the label is placed on the
+  // exterior of the element border so it does not overlap child elements.
+  // Horizontal labels: anchor = opposite of the side (e.g. east port → west-anchored text, outside).
+  // Vertical labels:   same opposite side but rotated 90°, keeping text readable.
+  let name-anchor = if outside-name {
+    if name-rotate { rotate-anchor(opposite-anchor(side)) }
+    else           { opposite-anchor(side) }
+  } else {
+    if name-rotate { rotate-anchor(side) } else { side }
+  }
+
   draw.content(
     pos,
-    anchor: if name-rotate {rotate-anchor(side)} else {side},
+    anchor: name-anchor,
     padding: 2pt,
     angle: if name-rotate {90deg} else {0deg},
     name
@@ -60,7 +73,8 @@
   tl, tr, br, bl,
   ports,
   ports-margins,
-  debug: false
+  debug: false,
+  outside-name: false,
 ) = {
   let sides = (
     "north": (tl, tr),
@@ -109,7 +123,8 @@
         pos,
         prev: pos-prev,
         next: pos-next,
-        debug: debug
+        debug: debug,
+        outside-name: outside-name,
       )
     }
   }