Route past round pads by their outline, not their bounding square

A circle pad was its bounding box in both the grid and the exact check, so a
4 mm mounting hole's square corners refused legal routes 0.8 mm clear of the
real copper. It is now a 16-sided polygon whose sides touch the circle, so
the router is never closer than KiCad measures. diagnose.py takes --seed.

bench/diagnose.py

@@ -32,8 +32,10 @@ from freeroute.route.exact_router import route_board_exact
 from freeroute.route.grid_router import GridRouter, _ends_of
 from freeroute.route.pipeline import (
     _mm_to_board,
+    _net_widths_board,
     _rule_clearance_dsn,
     _rule_width_dsn,
+    _via_drill_board,
     _via_half_board,
 )
 
@@ -183,7 +185,7 @@ def _flood(router: GridRouter, pin, net_no: int, conns) -> tuple[int, Counter]:
 
 def diagnose(
     dsn_text: str, edge_clearance_mm: float | None, resolution: int = 2, shove: bool = False,
-    access_cost: float = 0.0,
+    access_cost: float = 0.0, hole_to_hole_mm: float = 0.25, seed: int | None = None,
 ) -> dict:
     dsn = parse_dsn(dsn_text)
     names = {i + 1: n.name for i, n in enumerate(dsn.nets)}
@@ -199,6 +201,11 @@ def diagnose(
         resolution=resolution,
         shove=shove,
         access_cost=access_cost,
+        seed=seed,
+        # the product's configuration: net-class widths and hole spacing
+        net_widths=_net_widths_board(dsn, scale),
+        via_drill=_via_drill_board(dsn, scale),
+        hole_to_hole=_mm_to_board(dsn, scale, hole_to_hole_mm) or 0,
     )
     routed = seen["router"]
     best = routed._diag_best
@@ -270,11 +277,13 @@ def main(argv: list[str] | None = None) -> int:
     ap.add_argument("--grid-resolution", type=int, default=2, metavar="K")
     ap.add_argument("--shove", action="store_true", help="as mckicad routes")
     ap.add_argument("--access-cost", type=float, default=0.0)
+    ap.add_argument("--seed", type=int, help="route in this shuffled order, as bench.py does")
+    ap.add_argument("--hole-to-hole", type=float, default=0.25, metavar="MM")
     ap.add_argument("--json", type=Path, help="also write the full table here")
     args = ap.parse_args(argv)
 
     report = diagnose(args.dsn.read_text(), args.edge_clearance, args.grid_resolution, args.shove,
-                      args.access_cost)
+                      args.access_cost, args.hole_to_hole, args.seed)
     for row in report["failures"]:
         extra = ""
         for w in row.get("walled", []):

bench/drc_check.sh

@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+# Route one KiCad board with freeroute and judge the result with KiCad's DRC.
+#
+#   bench/drc_check.sh [--keep] <board.kicad_pcb> <out-dir> [freeroute args...]
+#
+# Copies the board (and its .kicad_pro) into <out-dir>, strips its tracks and
+# vias unless --keep is given (then they reach the router as fixed wiring),
+# exports the DSN through mckicad, routes, applies the session, and runs DRC
+# with zones refilled at every severity. Prints one line: time, copper added,
+# shorts, opens, hole problems (whatever severity the board gives them) and
+# the other errors. The source board is never touched.
+#
+# FREEROUTE (default: this checkout's .venv/bin/freeroute) and MCK (default
+# ~/claude/mckicad) pick the builds to judge.
+set -euo pipefail
+keep=0
+if [[ "${1:-}" == "--keep" ]]; then keep=1; shift; fi
+src="$1"; out="$2"; shift 2
+here="$(cd "$(dirname "$0")/.." && pwd)"
+FREEROUTE="${FREEROUTE:-$here/.venv/bin/freeroute}"
+MCK="${MCK:-$HOME/claude/mckicad}"
+rm -rf "$out"; mkdir -p "$out"
+cp "${src%.kicad_pcb}.kicad_pro" "$out/board.kicad_pro" 2>/dev/null || true
+
+if [[ $keep == 1 ]]; then
+    cp "$src" "$out/board.kicad_pcb"
+else
+    (cd "$MCK" && uv run --no-sync python - "$src" "$out/board.kicad_pcb" <<'EOF'
+import sys
+from mckicad.utils.sexp_tree import parse
+text = open(sys.argv[1]).read()
+spans = sorted((c.span for c in parse(text).children if c.tag in ("segment", "arc", "via")), reverse=True)
+for a, b in spans:
+    text = text[:a] + text[b:]
+open(sys.argv[2], "w").write(text)
+EOF
+    )
+fi
+
+(cd "$MCK" && uv run --no-sync python -c "
+from mckicad.utils.freerouting import FreeRoutingEngine
+assert FreeRoutingEngine().export_dsn_from_kicad('$out/board.kicad_pcb', '$out/board.dsn', {})") \
+    >/dev/null 2>&1 || { echo "$out: DSN export failed"; exit 1; }
+
+start=$(date +%s.%N)
+"$FREEROUTE" "$out/board.dsn" -do "$out/board.ses" "$@" >"$out/route.log" 2>&1 || true
+secs=$(python3 -c "print(round($(date +%s.%N)-$start,1))")
+[[ -s "$out/board.ses" ]] || { echo "$out: no session ($(tail -1 "$out/route.log"))"; exit 1; }
+
+(cd "$MCK" && uv run --no-sync python -c "
+from mckicad.utils.ses_apply import apply_ses_to_board as a
+r = a('$out/board.kicad_pcb', '$out/board.ses', '$out/board.kicad_pcb')
+print(r['segments_added'], r['vias_added'])" 2>/dev/null) >"$out/apply.txt"
+
+kicad-cli pcb drc --refill-zones --format json --severity-all \
+    -o "$out/drc.json" "$out/board.kicad_pcb" >/dev/null 2>&1 || true
+python3 - "$out" "$secs" <<'EOF'
+import collections, json, sys
+out, secs = sys.argv[1:]
+seg, via = open(f"{out}/apply.txt").read().split()
+d = json.load(open(f"{out}/drc.json"))
+errors = collections.Counter(v["type"] for v in d["violations"] if v.get("severity") == "error")
+other = collections.Counter(v["type"] for v in d["violations"] if v.get("severity") != "error")
+holes = {k: errors.pop(k, 0) + other.get(k, 0) for k in ("holes_co_located", "hole_to_hole")}
+print(f"{out}: {secs}s  {seg} seg {via} via  shorts {errors.pop('shorting_items', 0)}  "
+      f"opens {len(d.get('unconnected_items', []))}  holes {holes}  errors {dict(errors)}")
+EOF

src/freeroute/board/build.py

@@ -12,9 +12,10 @@ model. It mirrors what FreeRouting's ``Structure.create_board`` / ``Library`` /
 * padstacks x placement -> :class:`Pin` items
 * keepouts -> :class:`ObstacleArea` items
 
-Pad geometry: a rectangle pad becomes an exact :class:`IntBox`; a circle pad its
+Pad geometry: a rectangle pad becomes an exact :class:`IntBox`; a circle pad a
-bounding box (documented approximation pending an exact circle tile); a convex
+16-sided :class:`Simplex` drawn just outside it (its corners stand out by 2% of
-polygon pad an exact :class:`Simplex`. Every pad is placed centred on its pin
+the radius, where the bounding box's stood out by 41%); a convex polygon pad an
+exact :class:`Simplex`. Every pad is placed centred on its pin
 location, so it contains that location by construction. Component rotation is
 applied to the pin position; the pad tile itself is not rotated (irrelevant to
 the containment invariant, and pads are centre-symmetric in practice).
@@ -249,7 +250,7 @@ def _placed_pad_tile(shape: Shape, place, dsn_pin, transform: CoordinateTransfor
         r = round(transform.dsn_to_board(shape.diameter / 2))
         cx = round(transform.dsn_to_board(centre.x))
         cy = round(transform.dsn_to_board(centre.y))
-        return IntBox(cx - r, cy - r, cx + r, cy + r)
+        return _circle_tile(cx, cy, r)
     if isinstance(shape, Rectangle):
         x0, y0, x1, y1 = shape.coords[:4]
         corners = [(x0, y0), (x1, y0), (x1, y1), (x0, y1)]
@@ -268,15 +269,65 @@ def _placed_pad_tile(shape: Shape, place, dsn_pin, transform: CoordinateTransfor
     for x, y in corners:
         p = _to_board_offset(place, x, y, dsn_pin.rotation)
         pts.append(IntPoint(round(transform.dsn_to_board(p.x)), round(transform.dsn_to_board(p.y))))
-    if len(pts) >= 3:
+    # An oval's padded corners are not in outline order, and a mirrored
-        simplex = Simplex.from_corners(pts)
+    # part reverses the winding: take the convex hull, then either winding.
-        if not simplex.is_empty():
+    hull = _convex_hull(pts)
-            return simplex
+    if len(hull) >= 3:
+        for corners in (hull, hull[::-1]):
+            simplex = Simplex.from_corners(corners)
+            if not simplex.is_empty():
+                return simplex
     xs = [p.x for p in pts] or [0]
     ys = [p.y for p in pts] or [0]
     return IntBox(min(xs), min(ys), max(xs), max(ys))
 
 
+_CIRCLE_SIDES = 16
+
+
+def _circle_tile(cx: int, cy: int, r: int):
+    """A polygon around the circle, every side touching it. A square around a
+    big round pad (a mounting hole) puts phantom copper in its corners that
+    blocks legal routes past it; this stays outside the circle, so the router
+    is still never closer than KiCad measures."""
+    if r < 8:
+        return IntBox(cx - r, cy - r, cx + r, cy + r)
+    reach = r / math.cos(math.pi / _CIRCLE_SIDES)
+    corners = []
+    for k in range(_CIRCLE_SIDES):
+        a = (k + 0.5) * 2 * math.pi / _CIRCLE_SIDES
+        dx, dy = reach * math.cos(a), reach * math.sin(a)
+        # round away from the centre so the polygon never cuts into the circle
+        corners.append(IntPoint(cx + math.copysign(math.ceil(abs(dx)), dx),
+                                cy + math.copysign(math.ceil(abs(dy)), dy)))
+    corners = [IntPoint(int(p.x), int(p.y)) for p in corners]
+    for winding in (corners, corners[::-1]):
+        simplex = Simplex.from_corners(winding)
+        if not simplex.is_empty():
+            return simplex
+    return IntBox(cx - r, cy - r, cx + r, cy + r)
+
+
+def _convex_hull(pts: list[IntPoint]) -> list[IntPoint]:
+    """The convex hull of ``pts`` counter-clockwise, collinear points dropped."""
+    ps = sorted({(p.x, p.y) for p in pts})
+    if len(ps) < 3:
+        return [IntPoint(x, y) for x, y in ps]
+
+    def cross(o, a, b):
+        return (a[0] - o[0]) * (b[1] - o[1]) - (a[1] - o[1]) * (b[0] - o[0])
+
+    def half(points):
+        out: list[tuple[int, int]] = []
+        for p in points:
+            while len(out) >= 2 and cross(out[-2], out[-1], p) <= 0:
+                out.pop()
+            out.append(p)
+        return out[:-1]
+
+    return [IntPoint(x, y) for x, y in half(ps) + half(ps[::-1])]
+
+
 def _pad_tile(shape: Shape, transform: CoordinateTransform):
     """A board-relative pad tile from a DSN padstack shape (centred near origin)."""
     if isinstance(shape, Rectangle):
@@ -286,7 +337,7 @@ def _pad_tile(shape: Shape, transform: CoordinateTransform):
         r = round(transform.dsn_to_board(shape.diameter / 2))
         cx = round(transform.dsn_to_board(shape.center_x))
         cy = round(transform.dsn_to_board(shape.center_y))
-        return IntBox(cx - r, cy - r, cx + r, cy + r)  # bounding-box approximation
+        return _circle_tile(cx, cy, r)
     if isinstance(shape, (Polygon, Path)):
         coords = shape.coords
         pts = [

src/freeroute/board/search_tree.py

@@ -188,6 +188,8 @@ class ShapeSearchTree:
         overlap). Static pad-vs-pad spacing in the source design is not counted.
         """
         for shape in self.all_shapes():
+            if not shape.routed:
+                continue  # a pair with routed copper is checked from that side
             expanded = shape.tile.offset(clearance)
             grown = None  # exact clearance region, built lazily only for diagonals
             for other in self.overlapping(expanded):

src/freeroute/route/exact_router.py

@@ -38,6 +38,7 @@ from freeroute.geometry import (
     IntPoint,
     Polyline,
     PolylineShape,
+    Simplex,
     segment_box,
     segment_octagon,
     shove_segment,
@@ -154,7 +155,9 @@ def route_board_exact(
         net = pin.net_nos[0] if pin.net_nos else -1
         pin_layers = frozenset(layer for layer in pin.layers if layer in signal_layers)
         if pin_layers:
-            tree.insert(TreeShape(next(owner), net, pin_layers, box))
+            # a rotated pad is checked against its outline, not its box
+            exact = pin.shape if _is_rotated(pin.shape) else None
+            tree.insert(TreeShape(next(owner), net, pin_layers, box, exact=exact))
     for net, copper_layers, box in board.get_fixed_copper():
         on = frozenset(layer for layer in copper_layers if layer in signal_layers)
         if on and not box.is_empty():
@@ -667,6 +670,10 @@ def _copper_boxes(wires, vias, half_width, via_layers, via_half=None):
     return boxes
 
 
+def _is_rotated(shape) -> bool:
+    return isinstance(shape, Simplex) and not shape.is_int_box()
+
+
 def _net_pins(board: BasicBoard, net_no: int, signal_layers) -> list[Pin]:
     return [
         pin

src/freeroute/route/grid_router.py

@@ -27,12 +27,14 @@ DRC-clean geometry, and blind/buried via spans.
 from __future__ import annotations
 
 import heapq
+import itertools
 import math
 import random
 
 from freeroute.board.board import BasicBoard
 from freeroute.board.items import ConductionArea, ObstacleArea, Pin, Via
-from freeroute.geometry import IntBox, IntPoint
+from freeroute.geometry import IntBox, IntPoint, Simplex
+from freeroute.geometry.octagon import overlaps_2d
 from freeroute.geometry.polyline import corner_box
 
 __all__ = ["GridRouter", "RouteResult", "route_board"]
@@ -123,6 +125,7 @@ class _Connection:
         "path",
         "narrow",
         "half",
+        "stubs",
     )
 
     def __init__(self, index: int, net_no: int, a: Pin, b: Pin) -> None:
@@ -138,6 +141,8 @@ class _Connection:
         self.via_cells: list[Cell] = []
         self.via_halo: list[Cell] = []
         self.halo_nodes: list[Node] = []
+        # each end's stub: its layer, its copper tiles, and the nodes it claims
+        self.stubs: list[tuple[int, list[IntBox], set[Node]]] = []
         # the pins and zones each end may use, and which pin the route ended
         # on (None when it ended on a zone)
         self.a_group: tuple[list[Pin], list] = ([a], [])
@@ -229,7 +234,7 @@ class GridRouter:
             (dx, dy)
             for dx in range(-reach, reach + 1)
             for dy in range(-reach, reach + 1)
-            if (dx or dy) and math.hypot(dx, dy) * self.step < need
+            if (dx or dy) and max(abs(dx), abs(dy)) * self.step < need
         ]
         # A via's copper is wider than a trace. Another net's trace needs its
         # centre via_half + clearance + half_width from the via's centre, so a
@@ -295,6 +300,9 @@ class GridRouter:
         # per-connection occupancy (owner = connection index)
         self._cell_owner: dict[Node, int] = {}
         self._via_owner: dict[Cell, int] = {}
+        # every connection whose via covers a cell, in claim order: a via two
+        # connections share still blocks after the first of them is ripped
+        self._via_claims: dict[Cell, list[int]] = {}
         # trace halos: node -> indices of the connections claiming it
         self._halo: dict[Node, list[int]] = {}
         self._rasterize_obstacles()
@@ -375,6 +383,19 @@ class GridRouter:
             shape.contains(IntPoint(c.x + dx, c.y + dy)) for dx in (-h, h) for dy in (-h, h)
         )
 
+    def _pad_cells(self, shape, box: IntBox, margin: int):
+        """Cells where a trace square ``margin`` wide around the centre overlaps
+        the pad: its box when it is one, else its exact (rotated) outline,
+        which is what the exact engine checks against."""
+        cells = self._cells_in_box(box, margin)
+        if not isinstance(shape, Simplex) or shape.is_int_box():
+            yield from cells
+            return
+        for cell in cells:
+            c = self._cell_center(cell)
+            if overlaps_2d(shape, IntBox(c.x - margin, c.y - margin, c.x + margin, c.y + margin)):
+                yield cell
+
     def _rasterize_obstacles(self) -> None:
         margin = self.clearance + self.half_width
         outline = self.board.outline
@@ -400,7 +421,7 @@ class GridRouter:
                     continue
                 net = item.net_nos[0] if item.net_nos else 0
                 pin_layers = [layer for layer in item.layers if layer in self.layers]
-                for cell in self._cells_in_box(box, margin):
+                for cell in self._pad_cells(item.shape, box, margin):
                     for layer in pin_layers:
                         self._pad_block.setdefault((*cell, layer), set()).add(net)
                 # Copper of the pin's own net: a trace inside it adds nothing,
@@ -589,18 +610,19 @@ class GridRouter:
         return self.half_width if conn.narrow else self._net_half.get(conn.net_no, self.half_width)
 
     def _spread_for(self, half: int) -> list[tuple[int, int]]:
-        """Cells a trace of ``half`` also needs free: those whose centre is
+        """Cells a trace of ``half`` also needs free: every cell out to its
-        within its extra half width (plus half a cell, for the grid)."""
+        extra half width, rounded up to whole cells. Blocks, halos and via
+        footprints are sized for a default-width trace, and copper is checked
+        as boxes, so anything within that square could be too close."""
         extra = half - self.half_width
         if extra <= 0:
             return []
-        reach = math.ceil(extra / self.step) + 1
+        reach = math.ceil(extra / self.step)
-        limit = extra + self.step / 2
         return [
             (dx, dy)
             for dx in range(-reach, reach + 1)
             for dy in range(-reach, reach + 1)
-            if (dx or dy) and math.hypot(dx, dy) * self.step <= limit
+            if dx or dy
         ]
 
     def _halo_for(self, half: int) -> list[tuple[int, int]]:
@@ -613,7 +635,7 @@ class GridRouter:
                 (dx, dy)
                 for dx in range(-reach, reach + 1)
                 for dy in range(-reach, reach + 1)
-                if (dx or dy) and math.hypot(dx, dy) * self.step < need
+                if (dx or dy) and max(abs(dx), abs(dy)) * self.step < need
             ]
         return offsets
 
@@ -634,8 +656,8 @@ class GridRouter:
         if not conn.b_group[0] and any(z.layer in self._power_layers for z in conn.b_group[1]):
             # the plane is everywhere: aim at where the route starts instead
             goal_cell = self._group_target(conn.a_group)
-        starts = self._group_ends(conn.a_group, conn.net_no, conns)
+        starts = self._group_ends(conn.a_group, conn.net_no, conns, allow_ripup)
-        goals = self._group_ends(conn.b_group, conn.net_no, conns)
+        goals = self._group_ends(conn.b_group, conn.net_no, conns, allow_ripup)
         if not starts or not goals:
             return None
         # A start that is already an end joins at once, except that ending on
@@ -656,10 +678,19 @@ class GridRouter:
         came_from: dict[Node, Node] = {}
         # a stub costs its length, so the nearest cell wins unless it is blocked
         # a pin end costs its stub; a zone or plane end is entered normally
-        goal_stub = {n: self._stub_cost(p, n) for n, p in goals.items() if isinstance(p, Pin)}
+        # (and in rip-up mode the rip penalty of whatever lies on it)
+        goal_stub = {
+            n: self._stub_cost(p, n) + self._end_penalty(p, n, net_no, allow_ripup, conns)
+            for n, p in goals.items()
+            if isinstance(p, Pin)
+        }
         for s in sorted(starts):
             pin = starts[s]
-            g_score[s] = self._stub_cost(pin, s) if isinstance(pin, Pin) else 0.0
+            g_score[s] = (
+                self._stub_cost(pin, s) + self._end_penalty(pin, s, net_no, allow_ripup, conns)
+                if isinstance(pin, Pin)
+                else 0.0
+            )
             heapq.heappush(open_heap, (g_score[s] + self._h(s, goal_cell), s))
 
         # Via footprints are checked lazily: a layer change goes on the heap as
@@ -790,24 +821,52 @@ class GridRouter:
             math.hypot(loc.x - point.x, loc.y - point.y) < reach for loc, reach in self._tht_holes
         )
 
+    def _stub_points(self, pin_location: IntPoint, cell: Cell) -> list[IntPoint]:
+        """The stub's corners, from the pin to its cell centre.
+
+        The direct segment is fine for 45-degree routing. Orthogonal routing
+        leaves the pin straight along the axis it is further off the cell on
+        and jogs across to the centre at the end: an L of two flush boxes,
+        which is what the exact check sees. A single slanted segment is
+        checked as its bounding box there, and a 1 mm trace to a column
+        0.1 mm off a 1.27 mm pitch pin's centreline then lands inside the
+        clearance of the pad next door, though the straight exit clears it.
+        """
+        end = self._cell_center(cell)
+        dx, dy = end.x - pin_location.x, end.y - pin_location.y
+        if not self._orthogonal or dx == 0 or dy == 0:
+            return [pin_location, end]
+        if abs(dx) >= abs(dy):
+            return [pin_location, IntPoint(end.x, pin_location.y), end]
+        return [pin_location, IntPoint(pin_location.x, end.y), end]
+
     def _stub_cells(self, pin_location: IntPoint, cell: Cell, half: int | None = None) -> list[Cell]:
         """Cells where another net's trace would come too close to the stub."""
         from freeroute.board.outline import _point_segment
 
-        end = self._cell_center(cell)
+        points = self._stub_points(pin_location, cell)
+        end = points[-1]
         reach = (half or self._cur_half) + self.half_width + self.clearance
         box = IntBox(
             min(pin_location.x, end.x), min(pin_location.y, end.y),
             max(pin_location.x, end.x), max(pin_location.y, end.y),
         )
+        legs = list(zip(points, points[1:], strict=False))
         return [
             c
             for c in self._cells_in_box(box, reach)
-            if _point_segment(self._cell_center(c), pin_location, end) < reach
+            if min(_point_segment(self._cell_center(c), a, b) for a, b in legs) < reach
         ]
 
     def _stub_clear(
-        self, pin: Pin, cell: Cell, layer: int, net_no: int, conns, keepouts_only: bool = False
+        self,
+        pin: Pin,
+        cell: Cell,
+        layer: int,
+        net_no: int,
+        conns,
+        keepouts_only: bool = False,
+        allow_ripup: bool = False,
     ) -> bool:
         keepouts = self._keepout_boxes.get(layer)
         if keepouts:
@@ -815,9 +874,9 @@ class GridRouter:
             # engine will: its copper grown by clearance must miss every keepout
             from freeroute.geometry.polyline import Polyline, PolylineShape
 
-            end = self._cell_center(cell)
+            points = self._stub_points(pin.location, cell)
-            if end != pin.location:
+            if points[-1] != pin.location:
-                for tile in PolylineShape(Polyline([pin.location, end]), self._cur_half).tiles():
+                for tile in PolylineShape(Polyline(points), self._cur_half).tiles():
                     grown = tile.offset(self.clearance)
                     if any(k.overlaps(grown if needs else tile) for k, needs in keepouts):
                         return False
@@ -827,14 +886,60 @@ class GridRouter:
                     return False
         if keepouts_only:
             return True
-        for c in self._stub_cells(pin.location, cell):
+        owners = self._stub_owners(pin, cell, layer, net_no, conns)
-            owner = self._cell_owner.get((*c, layer))
+        # in rip-up mode a route on the stub is one more to rip, unless it may not be
-            if owner is not None and conns[owner].net_no != net_no:
+        return not owners or (
-                return False
+            allow_ripup and all(conns[i].rip_count < self.rip_cap for i in owners)
+        )
+
+    def _stub_tiles(self, pin_location: IntPoint, cell: Cell, half: int) -> list[IntBox]:
+        """The stub's copper: its legs, and a square at each corner and at the
+        cell end, where the route carries on."""
+        points = self._stub_points(pin_location, cell)
+        tiles = [corner_box(point, half) for point in points[1:]]
+        if len(points) > 1 and points[-1] != pin_location:
+            from freeroute.geometry.polyline import Polyline, PolylineShape
+
+            tiles += PolylineShape(Polyline(points), half).tiles()
+        return tiles
+
+    def _stub_owners(
+        self, pin: Pin, cell: Cell, layer: int, net_no: int, conns, half: int | None = None
+    ) -> set[int]:
+        """Other nets' routes whose copper the stub from ``pin`` to ``cell`` would touch."""
+        owners: set[int] = set()
+        grown = None
+        for c in self._stub_cells(pin.location, cell, half):
+            node = (*c, layer)
+            owner = self._cell_owner.get(node)
+            if owner is not None and conns[owner].net_no != net_no and owner not in owners:
+                # Both stubs are off the grid, and each claims the cells a
+                # trace centred there would crowd, so two stubs side by side
+                # (neighbouring pins leaving straight) overlap in claims well
+                # before their copper comes near. Check those exactly.
+                other = [tiles for lay, tiles, nodes in conns[owner].stubs if node in nodes]
+                if other:
+                    if grown is None:
+                        grown = [
+                            t.offset(self.clearance)
+                            for t in self._stub_tiles(pin.location, cell, half or self._cur_half)
+                        ]
+                    if not any(g.overlaps(t) for tiles in other for t in tiles for g in grown):
+                        continue
+                owners.add(owner)
             via_owner = self._via_owner.get(c)
             if via_owner is not None and conns[via_owner].net_no != net_no:
-                return False
+                owners.add(via_owner)
-        return True
+        return owners
+
+    def _end_penalty(self, pin: Pin, node: Node, net_no: int, allow_ripup: bool, conns) -> float:
+        """Rip-up cost of starting or ending on ``node``: the routes on its
+        cell and on the stub to it, each at the penalty entering it would cost."""
+        if not allow_ripup:
+            return 0.0
+        owners = self._stub_owners(pin, node[:2], node[2], net_no, conns)
+        owners |= self._crossed_owners([node], net_no, conns)
+        return sum(self.rip_penalty * (1 + conns[i].rip_count) for i in owners)
 
     def _zone_nodes(self, zone) -> list[Node]:
         """Cells of a zone where a via of this net fits inside its copper; for a
@@ -882,11 +987,13 @@ class GridRouter:
                 return zone.name or "zone"
         return ""
 
-    def _group_ends(self, group, net_no: int, conns) -> dict[Node, Pin | None]:
+    def _group_ends(
+        self, group, net_no: int, conns, allow_ripup: bool = False
+    ) -> dict[Node, Pin | None]:
         """End nodes of a group, each mapped to its pin (None for a zone cell)."""
         ends: dict[Node, Pin | None] = {}
         for pin in group[0]:
-            for node in sorted(self._end_nodes(pin, net_no, conns)):
+            for node in sorted(self._end_nodes(pin, net_no, conns, allow_ripup)):
                 ends.setdefault(node, pin)
         for zone in group[1]:
             plane = zone.layer in self._power_layers
@@ -908,10 +1015,13 @@ class GridRouter:
             return (dx + dy) / self.step
         return math.hypot(dx, dy) / self.step
 
-    def _end_nodes(self, pin: Pin, net_no: int, conns) -> set[Node]:
+    def _end_nodes(self, pin: Pin, net_no: int, conns, allow_ripup: bool = False) -> set[Node]:
         """Nodes a route may start or end on for ``pin``: the nearest cell and
         its neighbours, where the cell is enterable and the stub to it is clear.
-        A crowded fine-pitch pin gets more than one way out."""
+        A crowded fine-pitch pin gets more than one way out. In rip-up mode a
+        cell or stub another route is on counts as enterable, as it does
+        everywhere else, or a pin whose only way out another net has taken
+        could never have it back."""
         layers = [layer for layer in pin.layers if layer in self.layers]
         cx, cy = self._cell_of(pin.location)
         nodes: set[Node] = set()
@@ -920,16 +1030,16 @@ class GridRouter:
             if not (0 <= cell[0] < self.cols and 0 <= cell[1] < self.rows):
                 continue
             for layer in layers:
-                if (dx or dy) and self._enter_cost(cell, layer, net_no, False, conns) is None:
+                if (dx or dy) and self._enter_cost(cell, layer, net_no, allow_ripup, conns) is None:
                     continue
-                if self._stub_clear(pin, cell, layer, net_no, conns):
+                if self._stub_clear(pin, cell, layer, net_no, conns, allow_ripup=allow_ripup):
                     nodes.add((*cell, layer))
         # Also offer exact escape stubs: a fine-pitch pin's nearby cells can be
         # a pocket inside its own pad that leads nowhere (the grid columns miss
         # the narrow legal band past the pad tip). The stub's length is its
         # cost, so it is only taken where a short step would not do.
         if self._orthogonal and self._crowded(pin, net_no) and self._trapped(pin, net_no, nodes):
-            nodes |= self._escape_nodes(pin, net_no, conns, layers, (cx, cy))
+            nodes |= self._escape_nodes(pin, net_no, conns, layers, (cx, cy), allow_ripup)
         if not nodes:  # nothing clear: fall back to the nearest cell, as before
             nodes = {(cx, cy, layer) for layer in layers}
             if self._keepout_boxes and not any(
@@ -995,14 +1105,16 @@ class GridRouter:
         self._trapped_cache[key] = trapped
         return trapped
 
-    def _escape_nodes(self, pin: Pin, net_no: int, conns, layers, origin: Cell) -> set[Node]:
+    def _escape_nodes(
+        self, pin: Pin, net_no: int, conns, layers, origin: Cell, allow_ripup: bool = False
+    ) -> set[Node]:
         """For a pin walled in on the grid (a fine-pitch pin whose legal band
         the grid columns miss): look along each axis for the first open cell
-        whose straight stub from the pin clears every other net's pad by the
+        whose stub from the pin clears every other net's pad by the full
-        full margin, measured exactly rather than on the grid."""
+        clearance, checked on the stub's copper tiles as the exact engine
-        from freeroute.board.outline import _segment_box
+        will rather than on the grid."""
+        from freeroute.geometry.polyline import Polyline, PolylineShape
 
-        margin = self.half_width + self.clearance
         reach = self._escape_cells
         near = [
             (p.shape.bounding_box(), set(p.layers))
@@ -1014,24 +1126,33 @@ class GridRouter:
         ]
         cx, cy = origin
         nodes: set[Node] = set()
-        for dx, dy in _NEIGHBOURS[:4]:
+        # the pin's own column or row and the one either side: two pins side
+        # by side can then jog apart at the end of their straight exits
+        for (dx, dy), side in itertools.product(_NEIGHBOURS[:4], (0, -1, 1)):
+            sx, sy = (side, 0) if dx == 0 else (0, side)
+            nodes_before = len(nodes)
             for k in range(2, reach + 1):
-                cell = (cx + dx * k, cy + dy * k)
+                cell = (cx + dx * k + sx, cy + dy * k + sy)
                 if not (0 <= cell[0] < self.cols and 0 <= cell[1] < self.rows):
                     break
-                end = self._cell_center(cell)
+                grown = [
+                    tile.offset(self.clearance)
+                    for tile in PolylineShape(
+                        Polyline(self._stub_points(pin.location, cell)), self._cur_half
+                    ).tiles()
+                ]
                 for layer in layers:
-                    if self._enter_cost(cell, layer, net_no, False, conns) is None:
+                    if self._enter_cost(cell, layer, net_no, allow_ripup, conns) is None:
                         continue
                     if any(
-                        layer in box_layers and _segment_box(pin.location, end, box) < margin
+                        layer in box_layers and any(g.overlaps(box) for g in grown)
                         for box, box_layers in near
                     ):
                         continue
-                    if self._stub_clear(pin, cell, layer, net_no, conns):
+                    if self._stub_clear(pin, cell, layer, net_no, conns, allow_ripup=allow_ripup):
                         nodes.add((*cell, layer))
-                if any(n[:2] == cell for n in nodes):
+                if len(nodes) > nodes_before:
-                    break  # the first open cell along this axis is enough
+                    break  # the first open cell along this line is enough
         return nodes
 
     def _relax(self, current, nxt, tentative, goal_cell, g_score, came_from, open_heap):
@@ -1081,19 +1202,25 @@ class GridRouter:
         conn.via_halo = []
         for cell in conn.via_cells:
             for c in self._via_cells(cell):
-                if c not in self._via_owner:
+                claims = self._via_claims.setdefault(c, [])
-                    self._via_owner[c] = conn.index
+                if conn.index not in claims:
+                    claims.append(conn.index)
                     conn.via_halo.append(c)
+                self._via_owner.setdefault(c, conn.index)
         ends = ((conn.a_end, wire_segs[0], 0), (conn.b_end, wire_segs[-1], -1)) if wire_segs else ()
+        conn.stubs = []
         for pin, (layer, cells), at in ends:
             if not isinstance(pin, Pin):
                 continue  # ended on a zone or a plane: no stub
             cell = cells[at]
+            claimed: set[Node] = set()
             for c in self._stub_cells(pin.location, cell, half):
                 node = (*c, layer)
                 if node not in self._cell_owner:
                     self._cell_owner[node] = conn.index
                     conn.trace_cells.append((c, layer))
+                    claimed.add(node)
+            conn.stubs.append((layer, self._stub_tiles(pin.location, cell, half), claimed))
         # A pin inside a wire keepout can only leave by a via. Its stub to the
         # cell centre would be track inside the keepout, so the via goes on
         # the pin itself (a via in its own pad) and the stub is left out.
@@ -1111,9 +1238,9 @@ class GridRouter:
                 continue
             points = [self._cell_center(c) for c in cells]
             if idx == 0 and isinstance(conn.a_end, Pin):
-                points.insert(0, conn.a_end.location)
+                points[0:0] = self._stub_points(conn.a_end.location, cells[0])[:-1]
             if idx == len(wire_segs) - 1 and isinstance(conn.b_end, Pin):
-                points.append(conn.b_end.location)
+                points.extend(self._stub_points(conn.b_end.location, cells[-1])[-2::-1])
             points = _simplify(points)
             if len(points) >= 2:
                 conn.wires.append((layer, points))
@@ -1129,8 +1256,16 @@ class GridRouter:
             if self._cell_owner.get((*cell, layer)) == conn.index:
                 del self._cell_owner[(*cell, layer)]
         for cell in conn.via_halo:
+            claims = self._via_claims.get(cell)
+            if claims is not None and conn.index in claims:
+                claims.remove(conn.index)
             if self._via_owner.get(cell) == conn.index:
-                del self._via_owner[cell]
+                if claims:
+                    self._via_owner[cell] = claims[0]
+                else:
+                    del self._via_owner[cell]
+            if claims is not None and not claims:
+                del self._via_claims[cell]
         conn.via_halo = []
         for node in conn.halo_nodes:
             claims = self._halo.get(node)
@@ -1140,6 +1275,7 @@ class GridRouter:
                     del self._halo[node]
         conn.halo_nodes = []
         conn.trace_cells = []
+        conn.stubs = []
         for cell in conn.via_cells:
             count = self._via_nets.get(cell)
             if count and count.get(conn.net_no):
@@ -1153,7 +1289,20 @@ class GridRouter:
         conn.rip_count += 1
         self._settle(conn, +1)
 
-    def _crossed_owners(self, path: list[Node], net_no: int, conns: list[_Connection]) -> set[int]:
+    def _crossed_owners(
+        self, path: list[Node], net_no: int, conns: list[_Connection], spread=None
+    ) -> set[int]:
+        """Connections whose copper or clearance ``path`` crosses; a trace
+        wider than the default crosses them on its ``spread`` cells too."""
+        spread = self._spread if spread is None else spread
+        if spread:
+            path = list(
+                dict.fromkeys(
+                    (x + dx, y + dy, layer)
+                    for x, y, layer in path
+                    for dx, dy in ((0, 0), *spread)
+                )
+            )
         owners: set[int] = set()
         for cx, cy, cl in path:
             owner = self._cell_owner.get((cx, cy, cl))
@@ -1272,7 +1421,16 @@ class GridRouter:
             path = self._search(conn, allow_ripup=True, conns=conns)
             if path is None:
                 return False
-            victims = [conns[i] for i in sorted(self._crossed_owners(path, conn.net_no, conns))]
+            crossed = self._crossed_owners(
+                path, conn.net_no, conns, self._spread_for(self._conn_half(conn))
+            )
+            # and the routes on the stubs from the pins to the path's ends
+            for end, node in ((conn.a_end, path[0]), (conn.b_end, path[-1])):
+                if isinstance(end, Pin):
+                    crossed |= self._stub_owners(
+                        end, node[:2], node[2], conn.net_no, conns, self._conn_half(conn)
+                    )
+            victims = [conns[i] for i in sorted(crossed)]
             if self.rollback:
                 return self._ripup_transaction(conn, path, victims, conns)
             for victim in victims:

tests/route/test_grid_exact_agreement.py

@@ -0,0 +1,227 @@
+"""The grid must not believe copper legal that the exact check then refuses.
+
+Each case is one way the two used to disagree on roomba-ESP12E: a rotated oval
+pad modelled as an inflated box (and opened to its own net), a via shared by
+two connections of a net losing its footprint when one of them is ripped, and
+a wider net class searched as if it were the default width.
+"""
+
+from __future__ import annotations
+
+import math
+
+import pytest
+
+from freeroute.board import build_board
+from freeroute.dsn import parse_dsn
+from freeroute.geometry import IntBox, Simplex
+from freeroute.route.grid_router import GridRouter
+from freeroute.route.pipeline import (
+    _rule_clearance_dsn,
+    _rule_width_dsn,
+    _via_half_board,
+    build_exact_routing_result,
+)
+
+# --- rotated oval pads -------------------------------------------------------
+
+
+def _socket_dsn(rotation: float, layout: str) -> str:
+    """A 1x4 2.54 mm socket strip (rect pin 1, oval pins 2-4) at ``rotation``,
+    each pin its own net, routed to a small SMD pad 0.9 mm away."""
+    cx, cy = 100000, -100000
+    t = math.radians(rotation)
+    ax = (math.cos(t), math.sin(t))
+    perp = (-math.sin(t), math.cos(t))
+    places = []
+    for i in range(4):
+        px, py = cx + 2540 * i * ax[0], cy + 2540 * i * ax[1]
+        side = 1 if i % 2 == 0 else -1
+        if layout == "y":
+            tx, ty = px, py + side * 9000
+        else:
+            tx, ty = px + side * 8000 * perp[0], py + side * 8000 * perp[1]
+        places.append(f"(place T{i + 1} {round(tx)} {round(ty)} front 0)")
+    nets = " ".join(f"(net N{i} (pins P3-{i + 1} T{i + 1}-1))" for i in range(4))
+    return f"""(pcb socket (parser) (resolution um 10) (unit um)
+  (structure
+    (layer F.Cu (type signal)) (layer B.Cu (type signal))
+    (boundary (path pcb 0  125000 -115000  85000 -115000  85000 -75000  125000 -75000
+      125000 -115000))
+    (via "Via[0-1]_800:400_um")
+    (rule (width 300) (clearance 250)))
+  (placement
+    (component S (place P3 {cx} {cy} front {rotation}))
+    (component T {" ".join(places)}))
+  (library
+    (image S (pin R 1 0 0) (pin O 2 2540 0) (pin O 3 5080 0) (pin O 4 7620 0))
+    (image T (pin t 1 0 0))
+    (padstack O (shape (path F.Cu 1727.2 0 -152.4 0 152.4))
+      (shape (path B.Cu 1727.2 0 -152.4 0 152.4)) (attach off))
+    (padstack R (shape (rect F.Cu -863.6 -1016 863.6 1016))
+      (shape (rect B.Cu -863.6 -1016 863.6 1016)) (attach off))
+    (padstack t (shape (rect F.Cu -500 -500 500 500)) (attach off))
+    (padstack "Via[0-1]_800:400_um" (shape (circle F.Cu 800)) (shape (circle B.Cu 800))
+      (attach off)))
+  (network {nets}
+    (class c N0 N1 N2 N3 (circuit (use_via "Via[0-1]_800:400_um"))
+      (rule (width 300) (clearance 250)))))"""
+
+
+def test_a_rotated_oval_pad_is_its_outline_not_its_bounding_box():
+    board = build_board(parse_dsn(_socket_dsn(60, "y")))
+    oval = next(p for p in board.get_pins() if p.component_ref == "P3" and p.name == "2")
+    assert isinstance(oval.shape, Simplex) and not oval.shape.is_int_box()
+    box = oval.shape.bounding_box()
+    assert oval.shape.contains(oval.location)
+    assert not oval.shape.contains(box.ll) and not oval.shape.contains(box.ur)
+
+
+@pytest.mark.parametrize("layout", ["y", "perp"])
+def test_routes_leaving_a_rotated_socket_pass_the_exact_check(layout):
+    result = build_exact_routing_result(
+        parse_dsn(_socket_dsn(60, layout)), resolution=2, shove=True
+    )
+    assert result.unrouted == []
+
+
+# --- a via two connections share --------------------------------------------
+
+_SHARED_VIA = """(pcb shared (parser) (resolution um 10) (unit um)
+  (structure
+    (layer Top (type signal)) (layer Bottom (type signal))
+    (boundary (path pcb 0  0 0  20000 0  20000 -20000  0 -20000  0 0))
+    (via "Via[0-1]_800:400_um")
+    (rule (width 300) (clearance 250)))
+  (library
+    (padstack p (shape (rect Top -400 -400 400 400)) (attach off))
+    (padstack "Via[0-1]_800:400_um" (shape (circle Top 800)) (shape (circle Bottom 800))
+      (attach off))
+    (image PAD (pin p 1 0 0)))
+  (placement (component PAD
+    (place G1 3000 -5000 front 0) (place G2 3000 -15000 front 0)
+    (place G3 17000 -10000 front 0) (place S1 3000 -10000 front 0)
+    (place S2 17000 -3000 front 0)))
+  (network (net GND (pins G1-1 G2-1 G3-1)) (net SIG (pins S1-1 S2-1))))"""
+
+
+def _line(a, b, layer):
+    (x, y), (x1, y1) = a, b
+    out = [(x, y, layer)]
+    while x != x1:
+        x += 1 if x1 > x else -1
+        out.append((x, y, layer))
+    while y != y1:
+        y += 1 if y1 > y else -1
+        out.append((x, y, layer))
+    return out
+
+
+def test_a_shared_via_keeps_its_footprint_when_one_user_is_ripped():
+    dsn = parse_dsn(_SHARED_VIA)
+    s = dsn.resolution.value
+    router = GridRouter(
+        build_board(dsn),
+        trace_width=round(_rule_width_dsn(dsn) * s),
+        clearance=round(_rule_clearance_dsn(dsn) * s),
+        via_half=_via_half_board(dsn, s),
+    )
+    conns = router._conns = router._build_connections()
+    gnd = [c for c in conns if len({c.a.component_ref, c.b.component_ref} & {"G1", "G2", "G3"})]
+    sig = next(c for c in conns if c not in gnd)
+    first, second = gnd
+    g3 = router._cell_of(next(p for p in router.board.get_pins() if p.component_ref == "G3").location)
+    via = (g3[0] - 10, g3[1])
+
+    def through_via(conn):
+        a, b = router._cell_of(conn.a.location), router._cell_of(conn.b.location)
+        return _line(a, via, 0) + _line(via, b, 1)
+
+    router._commit(first, through_via(first))
+    router._commit(second, through_via(second))
+    footprint = [c for c in router._via_cells(via) if c != via]
+    router._rip(first)
+
+    assert second.routed and via in second.via_cells
+    assert all(router._via_owner.get(c) == second.index for c in footprint)
+    # another net still keeps its distance from the via that is left
+    assert all(router._enter_cost_base(c, 0, sig.net_no, False, conns) is None for c in footprint)
+
+
+# --- a wider net class --------------------------------------------------------
+
+_WIDE = """(pcb wide (parser) (resolution um 10) (unit um)
+  (structure
+    (layer F.Cu (type signal))
+    (boundary (path pcb 0  0 0  20000 0  20000 -10000  0 -10000  0 0))
+    (rule (width 300) (clearance 250)))
+  (placement (component S (place P1 2000 -5000 front 0) (place P2 18000 -5000 front 0)
+     (place Q1 10000 {ylo} front 0) (place Q2 10000 {yhi} front 0)
+     (place Q3 10000 -1000 front 0) (place Q4 10000 -9000 front 0)))
+  (library (image S (pin pad 1 0 0)) (padstack pad (shape (rect F.Cu -600 -600 600 600)) (attach off)))
+  (network (net PWR (pins P1-1 P2-1)) (net SIG (pins Q1-1 Q3-1)) (net SIG2 (pins Q2-1 Q4-1))
+    (class Power PWR (rule (width 500) (clearance 250)))))"""
+
+
+@pytest.mark.parametrize("resolution", [1, 2])
+@pytest.mark.parametrize("gap", [900, 1000, 1075])
+def test_a_wide_net_past_pads_it_does_not_fit_between_is_not_refused(gap, resolution):
+    # 0.3 mm fits the gap between the two pads, 0.5 mm does not: the grid
+    # must see that, rather than lay it wide and have the exact check drop it
+    ylo, yhi = -5000 - gap // 2 - 600, -5000 + gap // 2 + 600
+    result = build_exact_routing_result(
+        parse_dsn(_WIDE.format(ylo=ylo, yhi=yhi)), resolution=resolution
+    )
+    assert result.unrouted == []
+
+
+def _wide_router():
+    dsn = parse_dsn(_WIDE.format(ylo=-6050, yhi=-3950))
+    s = dsn.resolution.value
+    pwr = next(i for i, net in enumerate(dsn.nets, 1) if net.name == "PWR")
+    return GridRouter(
+        build_board(dsn),
+        trace_width=round(_rule_width_dsn(dsn) * s),
+        clearance=round(_rule_clearance_dsn(dsn) * s),
+        resolution=2,
+        net_widths={pwr: 5000},
+    ), pwr
+
+
+def test_a_wide_trace_keeps_clear_of_a_default_one_at_the_grid_diagonal():
+    router, _pwr = _wide_router()
+    # 0.5 mm against 0.3 mm needs 0.25 + 0.25 + 0.15 = 0.65 mm between centres,
+    # on either axis, since the exact check compares boxes
+    need = 2500 + router.clearance + router.half_width
+    for dx, dy in [(2, 2), (2, 1), (1, 2)]:
+        assert max(dx, dy) * router.step < need
+        assert (dx, dy) in router._halo_for(2500)
+
+
+def test_a_wide_rip_up_route_counts_what_its_extra_width_crosses():
+    router, pwr_net = _wide_router()
+    conns = router._conns = router._build_connections()
+    pwr = next(c for c in conns if c.net_no == pwr_net)
+    other = next(c for c in conns if c.net_no != pwr_net)
+    # a default-width trace two cells from the wide route's path
+    x, y = 20, 5
+    router._commit(other, _line((x - 3, y + 2), (x + 3, y + 2), 0))
+    path = _line((x - 3, y), (x + 3, y), 0)
+    spread = router._spread_for(2500)
+    assert other.index not in router._crossed_owners(path, pwr.net_no, conns)
+    assert other.index in router._crossed_owners(path, pwr.net_no, conns, spread)
+
+
+def test_a_pad_cell_check_uses_the_rotated_outline():
+    board = build_board(parse_dsn(_socket_dsn(60, "y")))
+    router = GridRouter(board, trace_width=3000, clearance=2500, resolution=2)
+    oval = next(p for p in board.get_pins() if p.component_ref == "P3" and p.name == "2")
+    box = oval.shape.bounding_box()
+    margin = router.clearance + router.half_width
+    exact = set(router._pad_cells(oval.shape, box, margin))
+    boxed = set(router._cells_in_box(box, margin))
+    assert exact < boxed
+    for cell in boxed - exact:
+        c = router._cell_center(cell)
+        square = IntBox(c.x - margin, c.y - margin, c.x + margin, c.y + margin)
+        assert oval.shape.intersection(square).dimension() != 2

tests/route/test_real_board_geometry.py

@@ -51,19 +51,22 @@ def test_routes_keep_edge_clearance_at_a_rounded_corner():
                 assert outline.edge_distance(p) >= half + 500 * scale - 1
 
 
-@pytest.mark.parametrize(("resolution", "escape"), [(1, 2), (4, 5)])
+@pytest.mark.parametrize("resolution", [1, 4])
-def test_every_pin_of_a_half_millimetre_pitch_row_escapes(resolution, escape):
+def test_every_pin_of_a_half_millimetre_pitch_row_escapes(resolution):
     # Five 0.3 mm pads at 0.5 mm pitch, each wired to its own pad 8 mm away.
     # Between two neighbours a trace's centre has a legal band only 0.15 mm
-    # wide. At resolution 1 the 0.4 mm grid misses most bands; at 4 its
+    # wide. At resolution 4 the 0.1 mm columns cannot miss it. At resolution
-    # 0.1 mm columns cannot, and every pin gets out, as the JAR manages.
+    # 1 the 0.4 mm grid misses most bands, but a stub leaves its pin straight
+    # along the band and jogs to the column only past the pads, so every pin
+    # gets out there too, as the JAR manages (only 2 did before).
     places = " ".join(f"(place R{i} {6000 + 500 * i} -6000 front 0)" for i in range(5))
     places += " " + " ".join(f"(place F{i} {6000 + 500 * i} -14000 front 0)" for i in range(5))
     nets = " ".join(f"(net N{i} (pins R{i}-1 F{i}-1))" for i in range(5))
     result, _, _ = route_dsn_board_exact(
         parse_dsn(_dsn(f"(component P {places})", nets)), resolution=resolution
     )
-    assert len(result.routed_net_numbers) == escape
+    assert len(result.routed_net_numbers) == 5
+    assert result.drc_clean
 
 
 def test_resolution_one_has_no_halo_so_the_grid_is_unchanged():

tests/route/test_straight_pin_exits.py

@@ -0,0 +1,58 @@
+"""Pins of a 1.27 mm pitch row routed at 1.0 mm (the RN2483 module on the
+TTN Enschede mote). A trace centre has to stay within 0.06 mm of a pin's
+centreline to pass its neighbours, which no grid column hits, so a route
+leaves each pin straight along that line and only jogs to its column once
+past the pads. FreeRouting routes this row in full the same way."""
+
+from __future__ import annotations
+
+import pytest
+
+from freeroute.board import build_board
+from freeroute.board.items import Pin
+from freeroute.dsn import parse_dsn
+from freeroute.geometry import IntPoint
+from freeroute.route.grid_router import GridRouter
+from freeroute.route.pipeline import route_dsn_board_exact
+
+
+def _row(x0: int, pins: int = 6, skew: int = 3000) -> str:
+    places = " ".join(f"(place R{i} {x0 + 1270 * i} -5000 front 0)" for i in range(pins))
+    places += " " + " ".join(
+        f"(place T{i} {x0 + 1270 * i + skew} -15000 front 0)" for i in range(pins)
+    )
+    nets = " ".join(f"(net N{i} (pins R{i}-1 T{i}-1))" for i in range(pins))
+    return f"""(pcb t (parser) (resolution um 10) (unit um)
+  (structure (layer F.Cu (type signal)) (layer B.Cu (type signal))
+    (boundary (path pcb 0 0 0 30000 0 30000 -20000 0 -20000 0 0))
+    (via "Via[0-1]_600:400_um") (rule (width 1000) (clearance 200)))
+  (placement (component P {places}))
+  (library (image P (pin pad 1 0 0))
+    (padstack pad (shape (rect F.Cu -508 -762 508 762)) (attach off))
+    (padstack "Via[0-1]_600:400_um" (shape (circle F.Cu 600)) (shape (circle B.Cu 600))
+      (attach off)))
+  (network {nets}))"""
+
+
+@pytest.mark.parametrize("x0", [5000, 5150, 5300])
+def test_every_pin_of_a_row_leaves_straight_and_routes(x0):
+    # three offsets of the row against the grid; before, 2 or 3 of 6 routed
+    result, _, _ = route_dsn_board_exact(parse_dsn(_row(x0)), resolution=2)
+    assert len(result.routed_net_numbers) == 6
+    assert result.drc_clean
+
+
+def test_a_walled_in_pin_may_escape_to_the_column_either_side():
+    # two pins side by side leaving the same way can then jog apart
+    board = build_board(parse_dsn(_row(5000)))
+    router = GridRouter(board, trace_width=10000, clearance=2000, orthogonal=True, resolution=2)
+    router._conns = router._build_connections()
+    pin = next(
+        p for p in board.get_items()
+        if isinstance(p, Pin) and p.location == IntPoint(50000 + 2 * 12700, -50000)
+    )
+    net = pin.net_nos[0]
+    cx, cy = router._cell_of(pin.location)
+    nodes = router._escape_nodes(pin, net, router._conns, [0], (cx, cy))
+    columns = {x for x, y, _ in nodes if y != cy}
+    assert {cx - 1, cx, cx + 1} <= columns