Route wider net classes at their width, falling back where they don't fit

The grid is laid out for the default width; a wider trace also needs the
cells its extra half width reaches to be free, and claims a wider halo.
A connection that does not fit at its class width (typically at a
fine-pitch pin) is routed at the default instead and reported. A net is
written at its class width when all of its connections went in at it,
and the exact check verifies it at that width; nets that shove or the
diagonal pass reshaped go out at the default.

src/freeroute/route/exact_router.py

@@ -99,6 +99,7 @@ def route_board_exact(
     route_first: frozenset | None = None,
     access_cost: float = 0.0,
     rollback: bool = True,
+    net_widths: dict[int, int] | None = None,
 ) -> ExactRouteResult:
     """Route ``board`` orthogonally and verify the result with exact geometry.
 
@@ -131,6 +132,7 @@ def route_board_exact(
         route_first=route_first,
         access_cost=access_cost,
         rollback=rollback,
+        net_widths=net_widths,
     )
     edge = 0 if edge_clearance is None else edge_clearance
     outline = board.outline
@@ -177,18 +179,22 @@ def route_board_exact(
     # 25-pin supply net costs that one connection, not the whole net.
     rejected: list[tuple[int, str, str]] = []
     ends_list = result.connection_ends or [("?", "?", "")] * len(result.connections)
+    # each net is checked at the width it will be written at: its class's
+    # when all of its connections went in at that, else the default
+    net_half = dict(result.net_half)
     for (net_no, wires, vias), ends in sorted(
         zip(result.connections, ends_list, strict=False), key=lambda c: c[0][0]
     ):
-        boxes = _copper_boxes(wires, vias, half_width, via_layers, via_half)
-        wire_count = len(_copper_boxes(wires, [], half_width, via_layers, via_half))
+        wire_half = net_half.get(net_no, half_width)
+        boxes = _copper_boxes(wires, vias, wire_half, via_layers, via_half)
+        wire_count = len(_copper_boxes(wires, [], wire_half, via_layers, via_half))
         if any(
             tree.clearance_conflict(
                 box, net_no, layer, clearance, "wire" if i < wire_count else "via"
             )
             for i, (box, box_layers) in enumerate(boxes)
             for layer in box_layers
-        ) or _end_in_rule_area(tree, wires, half_width) or (
+        ) or _end_in_rule_area(tree, wires, wire_half) or (
             outline is not None and not all(outline.box_clear(b, edge) for b, _ in boxes)
         ):
             rejected.append((net_no, *ends))
@@ -247,6 +253,17 @@ def route_board_exact(
     for net_no, acc in accepted.items():
         clean.wires[net_no] = acc.wires
         clean.vias[net_no] = acc.vias
+    # shove and the diagonal pass lay copper at the default width: nets they
+    # recovered, and nets whose traces shove pushed aside
+    reshaped = (set(accepted) - accepted_before_recovery) | {
+        net for net, acc in accepted.items() if acc.shove_count
+    }
+    if diagonal:
+        reshaped = set(accepted)
+    clean.net_half = {
+        net: half for net, half in net_half.items() if net in accepted and net not in reshaped
+    }
+    clean.narrowed = list(result.narrowed)
 
     drc_clean = tree.has_violation(clearance) is None
     return ExactRouteResult(result=clean, tree=tree, drc_clean=drc_clean, shoves=shoves)