Merge feat/smooth: opt-in --smooth turns grid staircases into octilinear runs after routing

--smooth: no 45-degree leg shorter than two track widths
A short diagonal at a wire's end is a kink beside its pad, and the pour refilled round it left a copper sliver (KiCad copper_sliver) on the TerraHawk lights node. Small offsets now stay square jogs; chamfers get the same floor.
2026-10-17 11:35:22 -06:00 · 2026-10-17 11:15:47 -06:00 · 2026-10-17 09:35:45 -06:00 · 2026-10-10 09:39:07 -06:00 · 2026-10-07 20:54:02 -06:00 · 2026-10-07 20:12:51 -06:00
101 changed files with 2268 additions and 385 deletions
@@ -1,12 +1,12 @@
 # CLAUDE.md

-Guidance for Claude Code working in the `freeroute` repository.
+Guidance for Claude Code working in the `rpmroute` repository.

 ## What this is

 A native Python PCB autorouter: a Java-free reimplementation of the
 [FreeRouting](https://github.com/freerouting/freerouting) engine. Specctra DSN
-in, Specctra SES out, no JVM anywhere. Published on PyPI as `freeroute`
+in, Specctra SES out, no JVM anywhere. Published on PyPI as `rpmroute`
 (GPL-3.0-or-later, CalVer).

 ## Commands
@@ -16,7 +16,7 @@ uv sync
 uv run pytest -m "not oracle"        # the fast suite (this is what you run)
 uv run pytest -m oracle              # differential tests against the real JAR (needs Java)
 uv run ruff check src/ tests/
-uv run freeroute board.dsn --engine room --pack -do board.ses
+uv run rpmroute board.dsn --engine room --pack -do board.ses
 ```

 ## The three non-negotiable invariants
@@ -67,7 +67,7 @@ route/     grid_router | exact_router | room_router, shove, pipeline, cli
  decomposed into convex rooms joined by doors, so it routes off-grid channels
  the grid literally cannot see. DRC-clean. Supports `--pack` and `--shove`.

-The engine/option matrix lives in `freeroute.cli.ENGINE_OPTIONS` and is
+The engine/option matrix lives in `rpmroute.cli.ENGINE_OPTIONS` and is
 importable, so consumers can assert against it. **An unsupported combination is
 a hard error (exit 2), never a silent no-op.** Downstream code (`mckicad`) reads
 this matrix to avoid sending an invalid pair.
@@ -1,14 +1,23 @@
-# freeroute
+# rpmroute

-A native Python PCB autorouter: a Java-free reimplementation of the
-[FreeRouting](https://github.com/freerouting/freerouting) engine. Specctra DSN
-in, Specctra SES out, no JVM anywhere in the pipeline.
+A native Python PCB autorouter. Specctra DSN in, Specctra SES out, no JVM
+anywhere in the pipeline.
+
+It began as a Java-free port of the
+[FreeRouting](https://github.com/freerouting/freerouting) engine and has grown
+its own router since: negotiated congestion before routing, multi-pin nets
+routed as trees, every route checked against exact pad and copper shapes, and
+pin escapes along the pad's own axis for parts placed at an angle. On dense
+boards it now finishes more connections than the FreeRouting JAR, with no
+rule violations.
+
+It was called `freeroute` until 2026-10-07; that command still works.

 ## Why

 Toolchains that autoroute (`kicad-mcp` among them) do it by shelling out to
 `freerouting.jar`, which drags a JVM into every install and container image.
-`freeroute` reimplements the routing engine in pure Python, with no dependencies
+`rpmroute` reimplements the routing engine in pure Python, with no dependencies
 beyond the standard library, so the JAR step becomes a `pip install`.

 ## The contract
@@ -16,31 +25,31 @@ beyond the standard library, so the JAR step becomes a `pip install`.
 The entire integration surface is two Specctra files:

 ```
-board.dsn  ──▶  freeroute  ──▶  board.ses
+board.dsn  ──▶  rpmroute  ──▶  board.ses
 (unrouted)                       (routed session: traces + vias)
 ```

-`kicad-cli` already exports `.dsn` and imports `.ses`, so `freeroute` drops in
+`kicad-cli` already exports `.dsn` and imports `.ses`, so `rpmroute` drops in
 wherever `java -jar freerouting.jar` was invoked, and nothing else in the pipeline
 changes. The `-de` / `-do` / `-mp` flags are the JAR's, on purpose.

 ## Install

 ```bash
-uv tool install freeroute      # or: pipx install freeroute
+uv tool install rpmroute      # or: pipx install rpmroute
 ```

 ## Usage

 ```bash
 # a KiCad board: the exact engine, with the board's copper-to-edge rule
-freeroute board.dsn --engine exact --shove --edge-clearance 0.5 -do board.ses
+rpmroute board.dsn --engine exact --shove --edge-clearance 0.5 -do board.ses

-freeroute -de board.dsn -do board.ses     # the FreeRouting JAR spelling (grid engine)
-freeroute board.dsn --engine room --pack --shove -do board.ses
+rpmroute -de board.dsn -do board.ses     # the FreeRouting JAR spelling (grid engine)
+rpmroute board.dsn --engine room --pack --shove -do board.ses
 ```

-With no `-do` / `-o`, the SES goes to stdout. Connections freeroute could not
+With no `-do` / `-o`, the SES goes to stdout. Connections rpmroute could not
 make are listed on stderr; the SES is still written and the exit code stays 0,
 as with the JAR. Connections whose two ends sit in one zone of their net are
 listed separately, as left to that zone's fill.
@@ -99,7 +108,7 @@ What the opt-in passes buy you:
 - **`--diagonal`** (exact): a still-dropped 2-pin net is retried as a 45° trace
  covered by an exact integer octagon.

-## What freeroute reads from a KiCad DSN
+## What rpmroute reads from a KiCad DSN

 These were each checked against KiCad itself, pad by pad or with its DRC:

@@ -125,7 +134,7 @@ SES coordinates are written in resolution units, exactly as the JAR writes them.
 ## Library use

 ```python
-from freeroute.route import route
+from rpmroute.route import route

 ses_text = route(dsn_text, engine="exact", shove=True, edge_clearance_mm=0.5)
 ```
@@ -136,13 +145,13 @@ Alpha. Measured on two real KiCad 10 boards (the TerraHawk charge node's power
 stage and sense board, 2026-09-27), with every track stripped, then routed, then
 checked with `kicad-cli pcb drc --refill-zones`:

-| board | freeroute exact | FreeRouting JAR | DRC errors from freeroute |
+| board | rpmroute exact | FreeRouting JAR | DRC errors from rpmroute |
 |---|---|---|---|
 | power stage (40 x 30 mm) | 7 unconnected, ~5 s | 12 | 0 |
 | sense board (55 x 25 mm, 0.5 mm pitch MCU) | 41 unconnected, ~2.5 min | 32 | 0 |

 In the board owner's production flow (hand-routed power lanes kept, pours added
-after routing), freeroute completed the power stage with no unconnected items.
+after routing), rpmroute completed the power stage with no unconnected items.

 What it is **not**, stated plainly:

@@ -164,7 +173,7 @@ What it is **not**, stated plainly:

 For maximum completion on a dense board today, the JAR is still the stronger
 router. For routing without a JVM (CI, containers, an MCP server, a library
-call), freeroute routes legally and says what it could not do.
+call), rpmroute routes legally and says what it could not do.

 ## Development

@@ -37,8 +37,8 @@ import tempfile
 import threading
 import time

-NOT_ROUTED = re.compile(r"freeroute: (\d+) connection\(s\) not routed")
-TO_ZONE = re.compile(r"freeroute: (\d+) more connection\(s\) left to a zone fill")
+NOT_ROUTED = re.compile(r"rpmroute: (\d+) connection\(s\) not routed")
+TO_ZONE = re.compile(r"rpmroute: (\d+) more connection\(s\) left to a zone fill")


 def parse_boards(path: Path) -> list[tuple[str, Path, list[str]]]:
@@ -61,8 +61,8 @@ def parse_variant(spec: str) -> tuple[str, str | None, list[str]]:
    if not sep or not head:
        raise SystemExit(f"variant {spec!r}: want NAME=FLAGS or NAME@SRC=FLAGS")
    name, _, src = head.partition("@")
-    if src and not (Path(src) / "freeroute").is_dir():
-        raise SystemExit(f"variant {name}: {src} has no freeroute package")
+    if src and not (Path(src) / "rpmroute").is_dir():
+        raise SystemExit(f"variant {name}: {src} has no rpmroute package")
    return name, src or None, shlex.split(flags)


@@ -74,7 +74,7 @@ def run_one(board, variant, seed: int, timeout: float) -> dict:
        env["PYTHONPATH"] = src + os.pathsep + env.get("PYTHONPATH", "")
    with tempfile.TemporaryDirectory() as tmp:
        cmd = [
-            sys.executable, "-m", "freeroute.cli", str(dsn), "-do", f"{tmp}/out.ses",
+            sys.executable, "-m", "rpmroute.cli", str(dsn), "-do", f"{tmp}/out.ses",
            *board_flags, *flags, "--seed", str(seed),
        ]
        start = time.monotonic()
@@ -100,13 +100,18 @@ def run_one(board, variant, seed: int, timeout: float) -> dict:
        )
        rss_mb = round(usage.ru_maxrss / 1024)
        secs = round(time.monotonic() - start, 1)
+        try:
+            with open(f"{tmp}/out.ses", encoding="utf-8") as f:
+                vias = f.read().count("(via ")
+        except OSError:
+            vias = None
    missing = NOT_ROUTED.search(err)
    zone = TO_ZONE.search(err)
    return {
        "board": name, "variant": vname, "seed": seed, "status": status,
        "unrouted": int(missing.group(1)) if missing else 0,
        "to_zone": int(zone.group(1)) if zone else 0,
-        "secs": secs, "rss_mb": rss_mb,
+        "secs": secs, "rss_mb": rss_mb, "vias": vias,
        "tail": err.strip().splitlines()[-1] if status != "ok" and err.strip() else "",
    }

@@ -147,6 +152,16 @@ def report(rows: list[dict], boards, variants) -> None:
                    line += (f"   {dm:+.1f} ± {se:.1f}  ({better} better, {worse} worse,"
                             f" {len(diffs) - better - worse} same)  {verdict}")
            print(line)
+    # vias, where the runs recorded them (older result files did not)
+    print("\nvias per variant, summed over boards (mean over seeds per board)\n")
+    for vname, _, _ in variants:
+        total, boards_counted = 0.0, 0
+        for bname, _, _ in boards:
+            vs = [r["vias"] for k, r in ok.items() if k[:2] == (bname, vname) and r.get("vias") is not None]
+            if vs:
+                total += sum(vs) / len(vs)
+                boards_counted += 1
+        print(f"{vname:14} {total:8.1f} vias over {boards_counted} boards")
    failed = [r for r in rows if r["status"] != "ok"]
    for r in failed:
        print(f"FAILED {r['board']} {r['variant']} seed {r['seed']}: {r['status']} {r['tail']}")
@@ -23,14 +23,14 @@ import json
 from pathlib import Path
 import sys

-from freeroute.board import build_board
-from freeroute.board.search_tree import ShapeSearchTree
-from freeroute.dsn import parse_dsn
-from freeroute.geometry.octagon import overlaps_2d
-from freeroute.route import grid_router
-from freeroute.route.exact_router import route_board_exact
-from freeroute.route.grid_router import GridRouter, _ends_of
-from freeroute.route.pipeline import (
+from rpmroute.board import build_board
+from rpmroute.board.search_tree import ShapeSearchTree
+from rpmroute.dsn import parse_dsn
+from rpmroute.geometry.octagon import overlaps_2d
+from rpmroute.route import grid_router
+from rpmroute.route.exact_router import route_board_exact
+from rpmroute.route.grid_router import GridRouter, _ends_of
+from rpmroute.route.pipeline import (
    _mm_to_board,
    _net_widths_board,
    _rule_clearance_dsn,
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
-# Route one KiCad board with freeroute and judge the result with KiCad's DRC.
+# Route one KiCad board with rpmroute and judge the result with KiCad's DRC.
 #
-#   bench/drc_check.sh [--keep] <board.kicad_pcb> <out-dir> [freeroute args...]
+#   bench/drc_check.sh [--keep] <board.kicad_pcb> <out-dir> [rpmroute 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),
@@ -10,14 +10,14 @@
 # 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
+# RPMROUTE (or the older FREEROUTE; default: this checkout's .venv/bin/rpmroute) 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:-$here/.venv/bin/freeroute}"
+RPMROUTE="${RPMROUTE:-${FREEROUTE:-$here/.venv/bin/rpmroute}}"
 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
@@ -43,7 +43,7 @@ assert FreeRoutingEngine().export_dsn_from_kicad('$out/board.kicad_pcb', '$out/b
    >/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
+"$RPMROUTE" "$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; }

@@ -90,7 +90,7 @@ this is the structure the Python `reader.py` mirrors):

 **Python port status:** items 1 (tokenizer), the shape grammar, and every
 structure/library/network/placement/parser/resolution scope above are
-implemented in `src/freeroute/dsn/` this session (see below).
+implemented in `src/rpmroute/dsn/` this session (see below).

 ## 2. Board data model — `board/`

@@ -175,7 +175,7 @@ converge toward FreeRouting's free-space rooms. Not started this session.
  into the read result).

 ## Port order (this file drives the roadmap)
-1. **DSN parser** — done this session (`src/freeroute/dsn/`).
+1. **DSN parser** — done this session (`src/rpmroute/dsn/`).
 2. **SES writer** — next. Start with an empty/no-op session to prove the loop
   end-to-end through `kicad-cli pcb import specctra-ses`. See `SesWriter.java`
   and `SpecctraSesFileWriter.java`: `(session <name> (base_design <name>)
@@ -184,6 +184,6 @@ converge toward FreeRouting's free-space rooms. Not started this session.
 3. **Geometry primitives** — `geometry/planar` subset needed by the board model.
 4. **Board model** — `board` items + spatial index.
 5. **Autorouter** — maze/rip-up core, then optimize pass.
-6. **CLI + kicad-mcp integration** — `freeroute board.dsn -o board.ses`.
+6. **CLI + kicad-mcp integration** — `rpmroute board.dsn -o board.ses`.
 </content>
 </invoke>
@@ -43,7 +43,7 @@ the output. Match that I/O and the rest of `kicad-mcp` is unchanged.
 4. **Autorouter core** — maze routing with rip-up-and-retry. Start grid-based
   Manhattan/45° for an MVP; converge toward FreeRouting's approach. _(TBD.)_
 5. **Optimize pass** — via minimization, trace smoothing. _(TBD.)_
-6. **CLI + kicad-mcp integration** — `freeroute board.dsn -o board.ses`, then
+6. **CLI + kicad-mcp integration** — `rpmroute board.dsn -o board.ses`, then
   swap it in behind `kicad_mcp/utils/freerouting_engine.py`'s JAR step.

 ## Validation strategy
@@ -3,9 +3,9 @@ requires = ["hatchling"]
 build-backend = "hatchling.build"

 [project]
-name = "freeroute"
-version = "2026.07.14"
-description = "Native Python PCB autorouter — a Java-free port of the FreeRouting engine (Specctra DSN in, SES out)"
+name = "rpmroute"
+version = "2026.10.07"
+description = "Native Python PCB autorouter with negotiated congestion and tree routing (Specctra DSN in, SES out)"
 readme = "README.md"
 license = "GPL-3.0-or-later"
 license-files = ["LICENSE"]
@@ -40,14 +40,17 @@ requires-python = ">=3.10"
 dependencies = []

 [project.urls]
-"Homepage" = "https://git.supported.systems/warehack.ing/freeroute"
-"Repository" = "https://git.supported.systems/warehack.ing/freeroute"
-"Issues" = "https://git.supported.systems/warehack.ing/freeroute/issues"
-# The Java engine this is a port of; freeroute ships no upstream code.
-"Upstream" = "https://github.com/freerouting/freerouting"
+"Homepage" = "https://git.supported.systems/warehack.ing/rpmroute"
+"Repository" = "https://git.supported.systems/warehack.ing/rpmroute"
+"Issues" = "https://git.supported.systems/warehack.ing/rpmroute/issues"
+# Where it started: a port of the Java FreeRouting engine. It has since grown
+# its own router (negotiation, tree nets, exact checks) and ships no upstream code.
+"Origin" = "https://github.com/freerouting/freerouting"

 [project.scripts]
-freeroute = "freeroute.cli:main"
+rpmroute = "rpmroute.cli:main"
+# the name it had until 2026-10-07, kept so existing scripts keep working
+freeroute = "rpmroute.cli:main"

 [dependency-groups]
 dev = [
@@ -57,7 +60,7 @@ dev = [
 ]

 [tool.hatch.build.targets.wheel]
-packages = ["src/freeroute"]
+packages = ["src/rpmroute"]

 [tool.hatch.build.targets.sdist]
 # Ship the package, the licence, and the docs — nothing else. `reference/` is a
@@ -95,7 +98,7 @@ select = ["E", "W", "F", "I", "B", "C4", "UP", "SIM"]
 ignore = ["E501"]

 [tool.ruff.lint.isort]
-known-first-party = ["freeroute"]
+known-first-party = ["rpmroute"]
 force-sort-within-sections = true

 [tool.pytest.ini_options]
@@ -1,3 +0,0 @@
-"""freeroute — native Python PCB autorouter (Java-free FreeRouting port)."""
-
-__version__ = "0.1.0"
@@ -0,0 +1,3 @@
+"""rpmroute — native Python PCB autorouter (Java-free FreeRouting port)."""
+
+__version__ = "0.1.0"
@@ -1,9 +1,9 @@
-"""Board data model for freeroute.
+"""Board data model for rpmroute.

 The data model a parsed DSN produces and the (future) router operates on:
 layers, units, coordinate transform, nets, clearance matrix, the item hierarchy,
 and the :class:`BasicBoard` container. :func:`build_board` constructs a board
-from a :class:`~freeroute.dsn.model.DsnBoard`.
+from a :class:`~rpmroute.dsn.model.DsnBoard`.

 The routing operations (``RoutingBoard``) and the spatial ``ShapeSearchTree``
 belong to the router phase.
@@ -9,7 +9,7 @@ board-model invariants check.

 from __future__ import annotations

-from freeroute.geometry import IntBox
+from rpmroute.geometry import IntBox

 from .clearance import ClearanceMatrix
 from .items import ConductionArea, Item, ObstacleArea, Pin, Trace, Via
@@ -74,7 +74,7 @@ class BasicBoard:
        """Copper already routed on the board (the DSN's ``wiring``), as
        ``(net, layers, box)``. A track is its segments, its corners and the
        round caps at its ends (as squares); a via is its largest pad."""
-        from freeroute.geometry.polyline import Polyline, PolylineShape, corner_box
+        from rpmroute.geometry.polyline import Polyline, PolylineShape, corner_box

        out: list[tuple[int, frozenset[int], IntBox]] = []
        for item in self._items:
@@ -1,6 +1,6 @@
 """Build a :class:`BasicBoard` from a parsed DSN :class:`DsnBoard`.

-This is the load-bearing integration between :mod:`freeroute.dsn` and the board
+This is the load-bearing integration between :mod:`rpmroute.dsn` and the board
 model. It mirrors what FreeRouting's ``Structure.create_board`` / ``Library`` /
 ``Component`` / ``Network`` readers do collectively, but on the already-parsed
 ``DsnBoard``:
@@ -26,10 +26,10 @@ from __future__ import annotations
 import math
 import re

-from freeroute.dsn.model import DsnBoard
-from freeroute.dsn.shapes import Circle, Path, Polygon, Rectangle, Shape
-from freeroute.geometry import FloatPoint, IntBox, IntPoint, IntVector, Simplex
-from freeroute.geometry.polygon_shape import PolygonShape
+from rpmroute.dsn.model import DsnBoard
+from rpmroute.dsn.shapes import Circle, Path, Polygon, Rectangle, Shape
+from rpmroute.geometry import FloatPoint, IntBox, IntPoint, IntVector, Simplex
+from rpmroute.geometry.polygon_shape import PolygonShape

 from .board import BasicBoard
 from .clearance import ClearanceMatrix
@@ -3,22 +3,22 @@
 Ports the *data model* of ``board/Item.java`` and its subclasses (``Pin``,
 ``ObstacleArea``/``ConductionArea``, ``Via``, ``PolylineTrace``). The routing
 and search-tree machinery in the Java classes is out of scope here — these hold
-the geometry and connectivity a :class:`~freeroute.board.board.BasicBoard`
+the geometry and connectivity a :class:`~rpmroute.board.board.BasicBoard`
 needs and that the DSN-import invariants check.

 Coordinates are board units (DSN units scaled by the resolution). Shapes are the
-exact convex tiles / boxes from :mod:`freeroute.geometry`.
+exact convex tiles / boxes from :mod:`rpmroute.geometry`.

 ``Trace``/``Via`` are only produced by routing (an imported unrouted board has
 none); they are lightweight here and the router phase fleshes out
-``Trace`` with a proper :class:`~freeroute.geometry.Polyline` shape.
+``Trace`` with a proper :class:`~rpmroute.geometry.Polyline` shape.
 """

 from __future__ import annotations

 from dataclasses import dataclass, field

-from freeroute.geometry import IntBox, IntPoint
+from rpmroute.geometry import IntBox, IntPoint

 __all__ = ["Item", "Pin", "ObstacleArea", "ConductionArea", "Via", "Trace"]

@@ -126,7 +126,7 @@ class Trace(Item):
    """A routed trace (router-produced).

    Held as its corner points plus a half-width; the router phase attaches the
-    full :class:`~freeroute.geometry.Polyline` swept shape.
+    full :class:`~rpmroute.geometry.Polyline` swept shape.
    """

    layer: int = 0
@@ -9,7 +9,7 @@ from __future__ import annotations

 import math

-from freeroute.geometry import IntBox, IntPoint
+from rpmroute.geometry import IntBox, IntPoint


 class BoardOutline:
@@ -2,7 +2,7 @@

 Ports the query role of ``board/ShapeSearchTree*.java``. It replaces the exact
 router's occupancy grid: instead of rasterizing shapes into cells, it indexes
-each item's convex tiles (:class:`~freeroute.geometry.IntBox`) and answers
+each item's convex tiles (:class:`~rpmroute.geometry.IntBox`) and answers
 overlap / region queries with a broad phase (a bounding-box spatial hash) and an
 **exact** narrow phase (exact ``IntBox`` intersection). Insert and remove keep
 the index in step as traces are added.
@@ -18,7 +18,7 @@ from __future__ import annotations

 from dataclasses import dataclass

-from freeroute.geometry import IntBox, IntPoint, Simplex, overlaps_2d, segment_octagon, segment_slab
+from rpmroute.geometry import IntBox, IntPoint, Simplex, overlaps_2d, segment_octagon, segment_slab

 __all__ = ["TreeShape", "ShapeSearchTree"]

@@ -34,7 +34,7 @@ class TreeShape:

    ``exact`` / ``seg`` are set only for a 45-degree (diagonal) trace tile: ``tile``
    is then the bounding box (broad-phase only), ``exact`` is the tight octagon
-    copper :class:`~freeroute.geometry.Simplex`, and ``seg`` is ``(a, b,
+    copper :class:`~rpmroute.geometry.Simplex`, and ``seg`` is ``(a, b,
    half_width)`` so the clearance region can be rebuilt exactly on demand. For
    every orthogonal tile both are ``None`` and all code paths are byte-identical
    to the box-only tree.
@@ -237,3 +237,36 @@ class ShapeSearchTree:
                if overlaps_2d(grown, other_tile):
                    return shape
        return None
+
+    def violation_pairs(self, clearance: int) -> list[tuple[TreeShape, TreeShape, bool]]:
+        """Every different-net pair sharing a layer, at least one of them
+        routed, whose coppers come closer than ``clearance``: ``(routed tile,
+        other tile, touching)``. ``touching`` is True when the coppers
+        themselves overlap (a short, or copper inside a keepout); False for a
+        clearance violation. Each pair of tiles is reported once.
+
+        :meth:`has_violation` asks whether there is one; this lists them all,
+        for a report on copper that no engine has checked.
+        """
+        pairs: list[tuple[TreeShape, TreeShape, bool]] = []
+        seen: set[tuple[int, int]] = set()
+        for shape in self.all_shapes():
+            if not shape.routed:
+                continue
+            mine = shape.exact if shape.exact is not None else shape.tile
+            grown = shape.clearance_region(clearance)
+            for other in self.overlapping(grown.bounding_box()):
+                if other is shape or other.net_no == shape.net_no:
+                    continue
+                if not (shape.layers & other.layers):
+                    continue
+                key = (min(id(shape), id(other)), max(id(shape), id(other)))
+                if key in seen:
+                    continue
+                theirs = other.exact if other.exact is not None else other.tile
+                touching = overlaps_2d(mine, theirs)
+                if not touching and (not other.clearance or not overlaps_2d(grown, theirs)):
+                    continue  # a rule area only counts an overlap
+                seen.add(key)
+                pairs.append((shape, other, touching))
+        return pairs
@@ -8,7 +8,7 @@ resolution`` and zero offset (see ``Structure.create_board``).

 from __future__ import annotations

-from freeroute.geometry import FloatPoint, IntPoint
+from rpmroute.geometry import FloatPoint, IntPoint

 __all__ = ["CoordinateTransform"]

@@ -1,8 +1,8 @@
-"""freeroute command-line interface: Specctra DSN in, routed SES out.
+"""rpmroute command-line interface: Specctra DSN in, routed SES out.

 Flag-compatible with the FreeRouting JAR (``-de`` / ``-do`` / ``-mp``) so it can
 be dropped in wherever ``java -jar freerouting.jar`` was invoked, plus the
-freeroute-specific engine selection (``--engine``) and its opt-in passes.
+rpmroute-specific engine selection (``--engine``) and its opt-in passes.

 Not every engine supports every pass. The matrix below is the single source of
 truth; an unsupported combination is an error, never a silent no-op::
@@ -18,20 +18,28 @@ from __future__ import annotations
 import argparse
 import sys

-from freeroute.dsn.reader import parse_dsn
-from freeroute.route.orders import best_of_orders, promote_failures
-from freeroute.route.pipeline import (
+from rpmroute.dsn.reader import parse_dsn
+from rpmroute.route.orders import best_of_orders, promote_failures
+from rpmroute.route.pipeline import (
    build_exact_routing_result,
    build_rooms_routing_result,
    build_routing_result,
 )
-from freeroute.ses import write_ses
+from rpmroute.route.smooth import smooth
+from rpmroute.route.verify import verify_result
+from rpmroute.ses import write_ses

 #: which optional flags each engine actually implements. Anything not listed for
 #: an engine is rejected by :func:`_validate` rather than quietly ignored.
 ENGINE_OPTIONS: dict[str, frozenset[str]] = {
-    "grid": frozenset({"rip_up", "max_passes", "seed", "orders", "promote", "access", "negotiate", "rollback", "tree"}),
-    "exact": frozenset({"shove", "diagonal", "rip_up", "max_passes", "seed", "orders", "promote", "access", "negotiate", "rollback", "tree"}),
+    "grid": frozenset({
+        "rip_up", "max_passes", "seed", "orders", "promote", "access", "negotiate", "rollback",
+        "tree", "via_cost",
+    }),
+    "exact": frozenset({
+        "shove", "diagonal", "rip_up", "max_passes", "seed", "orders", "promote", "access",
+        "negotiate", "rollback", "tree", "window", "vias", "via_cost", "smooth",
+    }),
    "room": frozenset({"shove", "pack"}),
 }

@@ -49,6 +57,10 @@ _FLAG_NAMES = {
    "negotiate": "--negotiate",
    "rollback": "--no-rollback",
    "tree": "--no-tree",
+    "window": "--window-reroute",
+    "vias": "--reduce-vias",
+    "via_cost": "--via-cost",
+    "smooth": "--smooth",
 }


@@ -70,7 +82,7 @@ def _validate(parser: argparse.ArgumentParser, engine: str, requested: list[str]

 def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
-        prog="freeroute",
+        prog="rpmroute",
        description="Native PCB autorouter — route a Specctra DSN and write an SES session file.",
    )
    parser.add_argument("dsn", nargs="?", help="input Specctra .dsn file")
@@ -90,11 +102,12 @@ def build_parser() -> argparse.ArgumentParser:
    parser.add_argument(
        "--engine",
        choices=sorted(ENGINE_OPTIONS),
-        default="grid",
+        default="exact",
        help=(
-            "routing track: grid (default; multi-layer rip-up maze, highest coverage), "
-            "exact (orthogonal, exact-geometry DRC-verified output), "
-            "room (continuous expansion rooms, routes off-grid channels)"
+            "routing track: exact (default; every route checked against exact pad and "
+            "copper shapes, DRC-clean output), grid (quick maze on the grid alone: its "
+            "copper is NOT clearance-checked and can short), room (continuous expansion "
+            "rooms, routes off-grid channels; not clearance-checked either)"
        ),
    )
    parser.add_argument(
@@ -177,6 +190,19 @@ def build_parser() -> argparse.ArgumentParser:
        "board, where routes may share space at a price that rises where they compete; "
        "the contested cells then cost extra in the real routing (default 0: off)",
    )
+    parser.add_argument(
+        "--smooth",
+        action="store_true",
+        help="exact engine: after routing, turn grid staircases into straight and 45-degree "
+        "runs and chamfer right-angle corners; same nets, ends, vias and layers, and every "
+        "new piece of copper checked on exact shapes against the board edge, other nets "
+        "and keepouts",
+    )
+    parser.add_argument(
+        "--smooth-report",
+        action="store_true",
+        help="with --smooth (implies it): also print track length per layer before and after",
+    )
    parser.add_argument(
        "--no-rollback",
        dest="rollback",
@@ -194,6 +220,75 @@ def build_parser() -> argparse.ArgumentParser:
        "paired by a minimum spanning tree and a connection may end on copper its net "
        "has already routed",
    )
+    parser.add_argument(
+        "--window-reroute",
+        type=int,
+        metavar="N",
+        help="exact engine: after routing, N rounds of window re-routes: around each "
+        "connection still unrouted, the nets routed wholly inside a window are ripped and "
+        "the window routed again on a finer grid, kept only if fewer connections are left "
+        "unrouted; each round doubles the window's margin (default 0: off)",
+    )
+    parser.add_argument(
+        "--window-resolution",
+        type=int,
+        default=4,
+        metavar="K",
+        help="the window re-route's grid resolution (default 4)",
+    )
+    parser.add_argument(
+        "--window-budget",
+        type=float,
+        default=0.25,
+        metavar="F",
+        help="the window re-route stops starting windows once it has spent this share "
+        "of the routing's own time (default 0.25)",
+    )
+    parser.add_argument(
+        "--window-cap",
+        type=int,
+        default=40,
+        metavar="W",
+        help="at most this many windows per round, smallest first (default 40)",
+    )
+    parser.add_argument(
+        "--window-margin",
+        type=float,
+        default=1.5,
+        metavar="MM",
+        help="the first round's window margin around the stuck connection's pins (default 1.5)",
+    )
+    parser.add_argument(
+        "--via-cost",
+        type=float,
+        default=None,
+        metavar="C",
+        help="grid and exact engines: what a layer change costs the search, in grid "
+        "steps of track (default 10)",
+    )
+    parser.add_argument(
+        "--reduce-vias",
+        action="store_true",
+        default=None,
+        help="exact engine: after routing, route each net that has vias again on its own "
+        "with vias made dearer, everything else held fixed; its new copper is kept only "
+        "if it fails nothing new and has fewer vias",
+    )
+    parser.add_argument(
+        "--reduce-vias-budget",
+        type=float,
+        default=0.5,
+        metavar="F",
+        help="via reduction stops starting nets once it has spent this share of the "
+        "routing's own time (default 0.5)",
+    )
+    parser.add_argument(
+        "--reduce-vias-margin",
+        type=float,
+        default=2.0,
+        metavar="MM",
+        help="how far past its pins and copper a net may go when routed again (default 2.0)",
+    )
    parser.add_argument(
        "--hole-to-hole",
        type=float,
@@ -208,6 +303,15 @@ def build_parser() -> argparse.ArgumentParser:
        metavar="J",
        help="processes for --orders (default: one per order, up to the CPU count)",
    )
+    parser.add_argument(
+        "--strict",
+        action="store_true",
+        help=(
+            "exit with status 3 when the routed copper has shorts or clearance "
+            "violations (grid and room output is checked after routing; the "
+            "session file is still written)"
+        ),
+    )
    return parser


@@ -234,6 +338,10 @@ def main(argv: list[str] | None = None) -> int:
            ("negotiate", args.negotiate is not None),
            ("rollback", not args.rollback),
            ("tree", not args.tree_nets),
+            ("window", args.window_reroute is not None),
+            ("vias", args.reduce_vias is not None),
+            ("via_cost", args.via_cost is not None),
+            ("smooth", args.smooth or args.smooth_report),
        )
        if asked
    ]
@@ -248,7 +356,7 @@ def main(argv: list[str] | None = None) -> int:
        with open(dsn_path, encoding="utf-8") as f:
            dsn_text = f.read()
    except OSError as e:
-        print(f"freeroute: cannot read {dsn_path}: {e}", file=sys.stderr)
+        print(f"rpmroute: cannot read {dsn_path}: {e}", file=sys.stderr)
        return 2

    dsn = parse_dsn(dsn_text)
@@ -272,7 +380,17 @@ def main(argv: list[str] | None = None) -> int:
            "hole_to_hole_mm": args.hole_to_hole,
            "rollback": args.rollback,
            "tree_nets": args.tree_nets,
+            "window_reroute": args.window_reroute or 0,
+            "window_resolution": args.window_resolution,
+            "window_margin_mm": args.window_margin,
+            "window_budget": args.window_budget,
+            "window_cap": args.window_cap,
+            "reduce_vias": bool(args.reduce_vias),
+            "reduce_vias_budget": args.reduce_vias_budget,
+            "reduce_vias_margin_mm": args.reduce_vias_margin,
        }
+        if args.via_cost is not None:
+            options["via_cost"] = args.via_cost
    elif args.engine == "grid":
        options = {
            "layers": layers,
@@ -286,6 +404,8 @@ def main(argv: list[str] | None = None) -> int:
            "rollback": args.rollback,
            "tree_nets": args.tree_nets,
        }
+        if args.via_cost is not None:
+            options["via_cost"] = args.via_cost
    if args.engine == "room":
        result = build_rooms_routing_result(
            dsn, layers=layers, shove=args.shove, pack=args.pack,
@@ -298,14 +418,14 @@ def main(argv: list[str] | None = None) -> int:
            dsn_text, args.engine, options, rounds=args.promote_failures, seed=args.seed
        )
        counts = ", ".join(str(m) for m, _z in rounds)
-        print(f"freeroute: {len(rounds)} rounds, unrouted {counts}; kept the best", file=sys.stderr)
+        print(f"rpmroute: {len(rounds)} rounds, unrouted {counts}; kept the best", file=sys.stderr)
    elif args.orders and args.orders > 1:
        result, kept, tried = best_of_orders(
            dsn_text, args.engine, options, orders=args.orders, seed=args.seed, jobs=args.jobs
        )
        counts = ", ".join(f"{'default' if s is None else s}: {m}" for s, (m, _z) in tried)
        print(
-            f"freeroute: tried {len(tried)} orders, kept "
+            f"rpmroute: tried {len(tried)} orders, kept "
            f"{'the default order' if kept is None else f'--seed {kept}'} (unrouted {counts})",
            file=sys.stderr,
        )
@@ -314,17 +434,24 @@ def main(argv: list[str] | None = None) -> int:
    else:
        result = build_routing_result(dsn, seed=args.seed, **options)

+    if args.smooth or args.smooth_report:
+        report = smooth(dsn, result, edge_clearance_mm=args.edge_clearance)
+        print(f"rpmroute: {report.line()}", file=sys.stderr)
+        if args.smooth_report:
+            for row in report.table():
+                print(row, file=sys.stderr)
+
    ses_text = write_ses(dsn, result)
    missing = [u for u in result.unrouted if not u[3]]
    in_zone = [u for u in result.unrouted if u[3]]
    if missing:
        # the SES is still written; say plainly what it is missing
-        print(f"freeroute: {len(missing)} connection(s) not routed:", file=sys.stderr)
+        print(f"rpmroute: {len(missing)} connection(s) not routed:", file=sys.stderr)
        for net, a, b, _zone in missing:
            print(f"  {net}: {a} to {b}", file=sys.stderr)
    if result.narrowed:
        print(
-            f"freeroute: {len(result.narrowed)} connection(s) of a wider net class only fitted "
+            f"rpmroute: {len(result.narrowed)} connection(s) of a wider net class only fitted "
            "at the default width; their nets are written at the default width:",
            file=sys.stderr,
        )
@@ -332,18 +459,40 @@ def main(argv: list[str] | None = None) -> int:
            print(f"  {net}: {a} to {b}", file=sys.stderr)
    if in_zone:
        print(
-            f"freeroute: {len(in_zone)} more connection(s) left to a zone fill that may join them:",
+            f"rpmroute: {len(in_zone)} more connection(s) left to a zone fill that may join them:",
            file=sys.stderr,
        )
        for net, a, b, zone in in_zone:
            print(f"  {net}: {a} to {b} (both in zone {zone})", file=sys.stderr)

+    flawed = False
+    if args.engine != "exact":
+        # These engines route on approximations and do not check the copper
+        # they write: check it now against the exact shapes the exact engine
+        # uses, so shorts are reported rather than shipped.
+        check = verify_result(dsn, result)
+        flawed = not check.clean
+        print(
+            f"rpmroute: {args.engine} output checked on exact shapes: "
+            f"{check.shorts} short(s), {check.clearance} clearance violation(s)",
+            file=sys.stderr,
+        )
+        for kind, examples in (("short", check.short_examples), ("clearance", check.clearance_examples)):
+            for found in examples:
+                print(f"  {kind}: {found}", file=sys.stderr)
+        if flawed:
+            print(
+                f"rpmroute: WARNING: this {args.engine} routing is not DRC-clean; fix it in "
+                "KiCad or route with --engine exact (the default)",
+                file=sys.stderr,
+            )
+
    if args.output:
        with open(args.output, "w", encoding="utf-8") as f:
            f.write(ses_text)
    else:
        sys.stdout.write(ses_text)
-    return 0
+    return 3 if (flawed and args.strict) else 0


 if __name__ == "__main__":
@@ -1,13 +1,13 @@
-"""Specctra DSN parsing for freeroute.
+"""Specctra DSN parsing for rpmroute.

 Public API::

-    from freeroute.dsn import parse_dsn
+    from rpmroute.dsn import parse_dsn
    board = parse_dsn(dsn_text)

-``parse_dsn`` returns a typed :class:`~freeroute.dsn.model.DsnBoard`. The
-lower-level :func:`~freeroute.dsn.tokenizer.tokenize` and
-:func:`~freeroute.dsn.sexp.parse` are exposed for tooling and tests.
+``parse_dsn`` returns a typed :class:`~rpmroute.dsn.model.DsnBoard`. The
+lower-level :func:`~rpmroute.dsn.tokenizer.tokenize` and
+:func:`~rpmroute.dsn.sexp.parse` are exposed for tooling and tests.
 """

 from __future__ import annotations
@@ -22,7 +22,7 @@ class SExp:

    ``head`` is the text of the first token when it is an atom (e.g. ``pcb``,
    ``layer``, ``net``), else ``None``. ``items`` holds the remaining elements,
-    each either a :class:`~freeroute.dsn.tokenizer.Token` (a leaf atom/string)
+    each either a :class:`~rpmroute.dsn.tokenizer.Token` (a leaf atom/string)
    or a nested :class:`SExp`.
    """

@@ -1,4 +1,4 @@
-"""Planar geometry primitives for freeroute.
+"""Planar geometry primitives for rpmroute.

 A port of the subset of FreeRouting's ``geometry/planar`` package the router
 needs, with the exact-arithmetic types preserved. Arithmetic model per type:
@@ -231,7 +231,7 @@ class IntBox:
        return [FloatPoint(c.x, c.y) for c in self.corners()]

    def to_simplex(self):
-        """Return this box as a :class:`~freeroute.geometry.simplex.Simplex`.
+        """Return this box as a :class:`~rpmroute.geometry.simplex.Simplex`.

        Four directed border lines whose common right side is the box interior
        (ports ``IntBox.to_Simplex``).
@@ -6,7 +6,7 @@ Ports ``geometry/planar/FloatPoint.java``.
 keeps ``FloatPoint`` *outside* the exact ``Point`` hierarchy because float math
 is inexact; it is used for distances, rounding, and speed-over-accuracy paths.
 Its :meth:`side_of` has no reliable ``COLLINEAR`` result (numerical noise), so
-exact side tests must go through :class:`~freeroute.geometry.point.Point`.
+exact side tests must go through :class:`~rpmroute.geometry.point.Point`.
 """

 from __future__ import annotations
@@ -137,13 +137,13 @@ class FloatPoint:
    # --- rounding to integer points ----------------------------------------

    def round(self):
-        """Round to the nearest :class:`~freeroute.geometry.point.IntPoint`."""
+        """Round to the nearest :class:`~rpmroute.geometry.point.IntPoint`."""
        from .point import IntPoint

        return IntPoint(_round_half_up(self.x), _round_half_up(self.y))

    def bounding_box(self):
-        """Smallest :class:`~freeroute.geometry.box.IntBox` containing this point."""
+        """Smallest :class:`~rpmroute.geometry.box.IntBox` containing this point."""
        from .box import IntBox

        return IntBox(
@@ -2,12 +2,12 @@

 Ports ``geometry/planar/Line.java`` (the subset needed for the router's
 half-plane work). Like the upstream class, a ``Line`` is defined by two
-:class:`~freeroute.geometry.point.IntPoint` endpoints.
+:class:`~rpmroute.geometry.point.IntPoint` endpoints.

 **Arithmetic model: exact.** :meth:`side_of` uses an exact integer determinant,
-and :meth:`intersection` returns an :class:`~freeroute.geometry.point.IntPoint`
+and :meth:`intersection` returns an :class:`~rpmroute.geometry.point.IntPoint`
 when the crossing is integral and a
-:class:`~freeroute.geometry.point.RationalPoint` otherwise (``z == 0`` when the
+:class:`~rpmroute.geometry.point.RationalPoint` otherwise (``z == 0`` when the
 lines are parallel — the "point at infinity"). :meth:`intersection_approx` is
 the fast ``float`` path.
 """
@@ -1,7 +1,7 @@
 """``Polygon`` — a normalized corner list (no duplicate or collinear corners).

 Ports ``geometry/planar/Polygon.java``. Used as the corner normalizer behind
-:class:`~freeroute.geometry.polygon_shape.PolygonShape`.
+:class:`~rpmroute.geometry.polygon_shape.PolygonShape`.

 **Arithmetic model:** corner de-duplication and collinearity removal are
 **exact** (exact ``Point.side_of``); the winding-number test is approximate
@@ -2,7 +2,7 @@

 Ports ``geometry/planar/PolygonShape.java``, in particular the recursive
 ``split_to_convex`` that decomposes a simple polygon into convex
-:class:`~freeroute.geometry.simplex.Simplex` tiles — the decomposition the
+:class:`~rpmroute.geometry.simplex.Simplex` tiles — the decomposition the
 router's search tree relies on.

 **Arithmetic model:** corner orientation / convexity tests are **exact**
@@ -7,7 +7,7 @@ trace half-width — the copper region — as a set of exact convex tiles.

 **Arithmetic model: exact, integer.** The router that uses this routes
 *orthogonally* (axis-aligned segments), so each swept segment is an exact
-:class:`~freeroute.geometry.box.IntBox` (centreline offset by the half-width,
+:class:`~rpmroute.geometry.box.IntBox` (centreline offset by the half-width,
 squared at the ends). The 45-degree case (which needs ``IntOctagon`` caps to
 stay exact) is deferred; ``segment_box`` returns the axis-aligned bounding box
 for a diagonal segment, which is a *conservative* cover (it never under-reports
@@ -1,10 +1,10 @@
 """``Simplex`` — a convex region as the intersection of directed half-planes.

 Ports ``geometry/planar/Simplex.java``. A simplex is defined by an array of
-directed :class:`~freeroute.geometry.line.Line`s sorted by direction angle; the
+directed :class:`~rpmroute.geometry.line.Line`s sorted by direction angle; the
 region is the intersection of the *right* half-plane of each line. Corners are
 the exact intersections of consecutive border lines
-(:meth:`~freeroute.geometry.line.Line.intersection`).
+(:meth:`~rpmroute.geometry.line.Line.intersection`).

 **Arithmetic model: exact where it matters.** Corners and all point-containment
 tests are exact (exact line intersection + exact ``side_of``). ``offset`` is
@@ -3,11 +3,11 @@
 Ports the concrete (non-abstract) behaviour of ``geometry/planar/TileShape.java``
 that is defined purely in terms of the border lines and corners: point
 containment, area, centre of gravity, and border tests. Concrete subclasses
-(:class:`~freeroute.geometry.simplex.Simplex`) supply ``border_line_count``,
+(:class:`~rpmroute.geometry.simplex.Simplex`) supply ``border_line_count``,
 ``border_line``, ``corner`` and ``corner_approx``.

 **Arithmetic model:** containment and ``contains_on_border`` are **exact**
-(they use the exact :meth:`~freeroute.geometry.line.Line.side_of`); ``area`` and
+(they use the exact :meth:`~rpmroute.geometry.line.Line.side_of`); ``area`` and
 ``centre_of_gravity`` are approximate (``float``), as upstream.

 A convex tile is the intersection of the right half-planes of its directed
@@ -13,7 +13,7 @@ Ports ``geometry/planar/{Vector,IntVector,RationalVector}.java``.
  representing the affine vector ``(x/z, y/z)``; ``z`` is kept non-negative.
  Mirrors the upstream ``BigInteger`` triple. ``BigIntDirection`` is not needed
  because ``int`` is unbounded, so normalized directions are always
-  :class:`~freeroute.geometry.direction.IntDirection`.
+  :class:`~rpmroute.geometry.direction.IntDirection`.
 """

 from __future__ import annotations
@@ -1,9 +1,9 @@
-"""Autorouting for freeroute.
+"""Autorouting for rpmroute.

 An MVP grid-based maze router and the DSN-in / SES-out pipeline that makes
-freeroute a Java-free replacement for the ``freerouting.jar`` step::
+rpmroute a Java-free replacement for the ``freerouting.jar`` step::

-    from freeroute.route import route
+    from rpmroute.route import route
    ses_text = route(dsn_text)

 The router (:class:`GridRouter`) is intentionally simple — single-layer A* over
@@ -1,18 +1,18 @@
 """Exact-geometry routing track (orthogonal), built on the search tree.

-The grid MVP (:mod:`freeroute.route.grid_router`) approximates clearance with
+The grid MVP (:mod:`rpmroute.route.grid_router`) approximates clearance with
 cell occupancy and emits centrelines with no width-aware DRC check. This track
 keeps the grid's rip-up/multi-layer/via *topology* search (in orthogonal mode,
 so segments are axis-aligned) but replaces the occupancy check with an **exact**
-one: every item's copper is an exact :class:`~freeroute.geometry.IntBox` tile
-indexed in a :class:`~freeroute.board.search_tree.ShapeSearchTree`, and the
+one: every item's copper is an exact :class:`~rpmroute.geometry.IntBox` tile
+indexed in a :class:`~rpmroute.board.search_tree.ShapeSearchTree`, and the
 routed board is verified to have **no clearance violation** by exact tile
 intersection. A net whose copper would violate is dropped, so the output is
 DRC-clean by construction.

 **Shove (opt-in, ``shove=True``).** Before a dropped net is abandoned, the
 router tries to make room by *moving an existing trace aside* geometrically
-(:func:`~freeroute.geometry.shove_segment`) rather than dropping the incoming
+(:func:`~rpmroute.geometry.shove_segment`) rather than dropping the incoming
 net. A shove is accepted only if the moved trace still connects its pads, clears
 every other item exactly (via the tree), and stays in the board outline — so
 cleanliness is preserved. Shoves are bounded (``max_shove_depth`` and a
@@ -30,10 +30,10 @@ from __future__ import annotations
 from dataclasses import dataclass, field
 import math

-from freeroute.board.board import BasicBoard
-from freeroute.board.items import Pin, Via
-from freeroute.board.search_tree import ShapeSearchTree, TreeShape
-from freeroute.geometry import (
+from rpmroute.board.board import BasicBoard
+from rpmroute.board.items import Pin, Via
+from rpmroute.board.search_tree import ShapeSearchTree, TreeShape
+from rpmroute.geometry import (
    IntBox,
    IntPoint,
    Polyline,
@@ -44,7 +44,7 @@ from freeroute.geometry import (
    segment_slab,
    shove_segment,
 )
-from freeroute.geometry.polyline import corner_box
+from rpmroute.geometry.polyline import corner_box

 from .grid_router import RouteResult, route_board

@@ -106,6 +106,8 @@ def route_board_exact(
    net_widths: dict[int, int] | None = None,
    via_drill: int | None = None,
    hole_to_hole: int = 0,
+    only_nets: frozenset | None = None,
+    bounds: IntBox | None = None,
 ) -> ExactRouteResult:
    """Route ``board`` orthogonally and verify the result with exact geometry.

@@ -143,6 +145,8 @@ def route_board_exact(
        net_widths=net_widths,
        via_drill=via_drill,
        hole_to_hole=hole_to_hole,
+        only_nets=only_nets,
+        bounds=bounds,
    )
    edge = 0 if edge_clearance is None else edge_clearance
    outline = board.outline
@@ -151,38 +155,7 @@ def route_board_exact(
    owner = _counter()

    # static items: pad and keepout copper (routed=False)
-    for pin in board.get_pins():
-        if pin.shape is None:
-            continue
-        box = pin.shape.bounding_box()
-        if box.is_empty():
-            continue
-        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:
-            # 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():
-            tree.insert(TreeShape(next(owner), net, on, box))
-    for obstacle in board.get_obstacle_areas():
-        if obstacle.layer not in signal_layers:
-            continue
-        blocks = (
-            "all" if obstacle.blocks_wires and obstacle.blocks_vias
-            else "wires" if obstacle.blocks_wires else "vias"
-        )
-        for tile in obstacle.tiles:
-            box = tile.bounding_box()
-            if not box.is_empty():
-                tree.insert(
-                    TreeShape(
-                        next(owner), -1, frozenset({obstacle.layer}), box,
-                        blocks=blocks, clearance=obstacle.clearance,
-                    )
-                )
+    insert_static_copper(tree, board, signal_layers, owner)

    via_layers = frozenset(signal_layers)
    accepted: dict[int, _Accepted] = {}
@@ -259,7 +232,10 @@ def route_board_exact(
    # a net is dropped if it has a real ratsnest (>= 2 pins on a signal layer)
    # but was not accepted — whether the grid failed to route it or its exact
    # copper conflicted.
-    dropped = sorted(_routable_nets(board, signal_layers) - set(accepted))
+    routable = _routable_nets(board, signal_layers)
+    if only_nets is not None:  # a window re-route: the other nets are not ours to route
+        routable &= set(only_nets)
+    dropped = sorted(routable - set(accepted))

    shoves = 0
    if shove and dropped:
@@ -284,7 +260,7 @@ def route_board_exact(

    if diagonal:
        outline = board.bounding_box
-        for net_no in sorted(_routable_nets(board, signal_layers)):
+        for net_no in sorted(routable):
            _diagonalize(
                net_no, board, tree, accepted, owner, signal_layers, half_width, clearance, outline
            )
@@ -318,6 +294,43 @@ def route_board_exact(
 # --- 45-degree (diagonal) recovery -------------------------------------------


+def insert_static_copper(tree: ShapeSearchTree, board: BasicBoard, signal_layers, owner) -> None:
+    """Index the board's pads, fixed copper and keepouts (``routed=False``) on
+    ``signal_layers``: what routed copper is checked against."""
+    for pin in board.get_pins():
+        if pin.shape is None:
+            continue
+        box = pin.shape.bounding_box()
+        if box.is_empty():
+            continue
+        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:
+            # 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():
+            tree.insert(TreeShape(next(owner), net, on, box))
+    for obstacle in board.get_obstacle_areas():
+        if obstacle.layer not in signal_layers:
+            continue
+        blocks = (
+            "all" if obstacle.blocks_wires and obstacle.blocks_vias
+            else "wires" if obstacle.blocks_wires else "vias"
+        )
+        for tile in obstacle.tiles:
+            box = tile.bounding_box()
+            if not box.is_empty():
+                tree.insert(
+                    TreeShape(
+                        next(owner), -1, frozenset({obstacle.layer}), box,
+                        blocks=blocks, clearance=obstacle.clearance,
+                    )
+                )
+
+
 def _octilinear_candidates(a: IntPoint, b: IntPoint) -> list[list[IntPoint]]:
    """Octilinear (0/45/90/135-degree) polylines from ``a`` to ``b``.

@@ -626,7 +639,7 @@ def _conflicting_segment(corners, d_boxes, half_width, clearance):
        horizontal = a.y == b.y
        if not horizontal and a.x != b.x:
            continue  # skip diagonal grid stubs
-        from freeroute.geometry import segment_box
+        from rpmroute.geometry import segment_box

        seg = segment_box(a, b, half_width).offset(clearance)
        if any(seg.overlaps(box) for box in d_boxes):
@@ -31,11 +31,11 @@ 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, Simplex
-from freeroute.geometry.octagon import overlaps_2d, segment_slab
-from freeroute.geometry.polyline import corner_box, segment_box
+from rpmroute.board.board import BasicBoard
+from rpmroute.board.items import ConductionArea, ObstacleArea, Pin, Via
+from rpmroute.geometry import IntBox, IntPoint, Simplex
+from rpmroute.geometry.octagon import overlaps_2d, segment_slab
+from rpmroute.geometry.polyline import corner_box, segment_box

 __all__ = ["GridRouter", "RouteResult", "route_board"]

@@ -203,8 +203,18 @@ class GridRouter:
        via_drill: int | None = None,
        hole_to_hole: int = 0,
        tree_nets: bool = True,
+        only_nets: frozenset | None = None,
+        bounds: IntBox | None = None,
    ) -> None:
        self.board = board
+        # A window re-route routes some nets inside part of the board: only
+        # these nets get connections, and the grid covers only ``bounds``
+        # (cells outside it do not exist, so nothing is routed there).
+        self.only_nets = frozenset(only_nets) if only_nets is not None else None
+        self._bounds = bounds
+        # connections with an end outside ``bounds``: never searched, since
+        # the grid has no cells to reach that end by
+        self._outside: set[int] = set()
        # Multi-pin nets: pair a net's pin groups by a minimum spanning tree,
        # and let a connection start or end on copper its net already routed
        # (a T into the tree), not only on one chosen pin.
@@ -324,6 +334,11 @@ class GridRouter:
        self.layers = list(layers)

        box = board.bounding_box
+        if bounds is not None:
+            box = IntBox(
+                max(box.ll.x, bounds.ll.x), max(box.ll.y, bounds.ll.y),
+                min(box.ur.x, bounds.ur.x), min(box.ur.y, bounds.ur.y),
+            )
        self.origin_x = box.ll.x
        self.origin_y = box.ll.y
        self.cols = max(1, math.ceil((box.ur.x - box.ll.x) / self.step) + 1)
@@ -706,6 +721,8 @@ class GridRouter:
    def _search(
        self, conn: _Connection, allow_ripup: bool, conns: list[_Connection]
    ) -> list[Node] | None:
+        if conn.index in self._outside:
+            return None
        half = self._conn_half(conn)
        self._cur_half, self._spread = half, self._spread_for(half)
        try:
@@ -1079,7 +1096,7 @@ class GridRouter:

    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
+        from rpmroute.board.outline import _point_segment

        points = self._stub_points(pin_location, cell)
        reach = (half or self._cur_half) + self.half_width + self.clearance
@@ -1837,6 +1854,8 @@ class GridRouter:
        self._plane_nets: set[int] = set()
        nets = set(pins_by_net) | set(zones_by_net) | set(planes_by_net)
        # deterministic: fewer-pin nets first, then by net number
+        if self.only_nets is not None:
+            nets &= self.only_nets
        for net_no in sorted(nets, key=lambda n: (len(pins_by_net.get(n, [])), n)):
            zones = zones_by_net.get(net_no, []) + planes_by_net.get(net_no, [])
            groups = _connected_groups(
@@ -1859,14 +1878,19 @@ class GridRouter:
        self._net_conns: dict[int, list[_Connection]] = {}
        for conn in conns:
            self._net_conns.setdefault(conn.net_no, []).append(conn)
+        if self._bounds is not None:
+            self._outside = {
+                c.index for c in conns
+                if not (_group_inside(c.a_group, self._bounds) and _group_inside(c.b_group, self._bounds))
+            }
        return conns

    def _fixed_pieces(self, net_no: int) -> list[_FixedPiece]:
        """The net's tracks and vias already on the board, as connectivity."""
        cache = getattr(self, "_fixed_cache", None)
        if cache is None:
-            from freeroute.board.items import Trace
-            from freeroute.geometry.polyline import Polyline, PolylineShape, corner_box
+            from rpmroute.board.items import Trace
+            from rpmroute.geometry.polyline import Polyline, PolylineShape, corner_box

            cache = self._fixed_cache = {}
            for item in self.board.get_items():
@@ -2004,6 +2028,19 @@ def _group_label(group) -> str:
    return "/".join(parts) or "?"


+def _group_inside(group, bounds: IntBox) -> bool:
+    """A group has a pin inside ``bounds``, or a zone reaching into it."""
+    pins, zones = group
+    if any(bounds.ll.x <= p.location.x <= bounds.ur.x and bounds.ll.y <= p.location.y <= bounds.ur.y
+           for p in pins):
+        return True
+    for zone in zones:
+        box = zone.bounding_box()
+        if box.ll.x <= bounds.ur.x and bounds.ll.x <= box.ur.x and box.ll.y <= bounds.ur.y and bounds.ll.y <= box.ur.y:
+            return True
+    return False
+
+
 def _ends_of(conn) -> tuple[str, str]:
    """A readable description of what a connection joins."""
    return _group_label(conn.a_group), _group_label(conn.b_group)
@@ -2196,6 +2233,8 @@ def route_board(
    net_widths: dict[int, int] | None = None,
    via_drill: int | None = None,
    hole_to_hole: int = 0,
+    only_nets: frozenset | None = None,
+    bounds: IntBox | None = None,
 ) -> RouteResult:
    """Convenience wrapper: build a :class:`GridRouter` and route the board."""
    router = GridRouter(
@@ -2220,5 +2259,7 @@ def route_board(
        net_widths=net_widths,
        via_drill=via_drill,
        hole_to_hole=hole_to_hole,
+        only_nets=only_nets,
+        bounds=bounds,
    )
    return router.route()
@@ -15,8 +15,8 @@ from __future__ import annotations
 from concurrent.futures import ProcessPoolExecutor
 import os

-from freeroute.dsn import parse_dsn
-from freeroute.ses import RoutingResult
+from rpmroute.dsn import parse_dsn
+from rpmroute.ses import RoutingResult

 from .pipeline import build_exact_routing_result, build_routing_result

@@ -13,14 +13,17 @@ to DSN units (dividing by the resolution) for the SES ``(wire (path ...))`` and
 from __future__ import annotations

 import re
+import time

-from freeroute.board import build_board
-from freeroute.dsn import DsnBoard, parse_dsn
-from freeroute.ses import RoutedVia, RoutedWire, RoutingResult, write_ses
+from rpmroute.board import build_board
+from rpmroute.dsn import DsnBoard, parse_dsn
+from rpmroute.ses import RoutedVia, RoutedWire, RoutingResult, write_ses

 from .exact_router import ExactRouteResult, route_board_exact
 from .grid_router import RouteResult, route_board
 from .room_router import route_board_rooms
+from .vias import reduce_vias as reduce_vias_stage
+from .window import window_reroute as window_reroute_stage

 __all__ = ["route", "route_dsn_board", "build_routing_result"]

@@ -122,6 +125,7 @@ def route_dsn_board(
    hole_to_hole_mm: float = 0.25,
    rollback: bool = True,
    tree_nets: bool = True,
+    via_cost: float = 10.0,
 ) -> tuple[RouteResult, int, list[str]]:
    """Route a parsed :class:`DsnBoard`; return the board-unit result, the scale,
    and the layer names. ``layers`` restricts routing to those signal-layer
@@ -151,6 +155,7 @@ def route_dsn_board(
        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,
+        via_cost=via_cost,
    )
    return result, scale, [layer.name for layer in dsn.layers]

@@ -204,6 +209,7 @@ def build_routing_result(
    hole_to_hole_mm: float = 0.25,
    rollback: bool = True,
    tree_nets: bool = True,
+    via_cost: float = 10.0,
 ) -> RoutingResult:
    """Route ``dsn`` (grid track) and convert to a DSN-unit RoutingResult."""
    route, scale, layer_names = route_dsn_board(
@@ -215,6 +221,7 @@ def build_routing_result(
        hole_to_hole_mm=hole_to_hole_mm,
        rollback=rollback,
        tree_nets=tree_nets,
+        via_cost=via_cost,
    )
    return _to_routing_result(route, dsn, scale, layer_names)

@@ -237,6 +244,15 @@ def route_dsn_board_exact(
    hole_to_hole_mm: float = 0.25,
    rollback: bool = True,
    tree_nets: bool = True,
+    window_reroute: int = 0,
+    window_resolution: int = 4,
+    window_margin_mm: float = 1.5,
+    window_budget: float = 0.25,
+    window_cap: int = 40,
+    reduce_vias: bool = False,
+    reduce_vias_budget: float = 0.5,
+    reduce_vias_margin_mm: float = 2.0,
+    via_cost: float = 10.0,
 ) -> tuple[ExactRouteResult, int, list[str]]:
    """Route a parsed :class:`DsnBoard` with the exact-geometry (orthogonal,
    DRC-verified) track; return the exact result, the scale, and layer names.
@@ -248,29 +264,61 @@ def route_dsn_board_exact(
    edge_clearance_board = _mm_to_board(dsn, scale, edge_clearance_mm)
    width_board = round(_rule_width_dsn(dsn) * scale)
    clearance_board = round(_rule_clearance_dsn(dsn) * scale)
+    # the settings a window re-route repeats, at its own resolution
+    common = {
+        "heuristic_weight": heuristic_weight,
+        "via_half": _via_half_board(dsn, scale),
+        "edge_clearance": edge_clearance_board,
+        "trace_width": width_board,
+        "clearance": clearance_board,
+        "layers": layers,
+        "max_passes": max_passes,
+        "rip_up": rip_up,
+        "shove": shove,
+        "diagonal": diagonal,
+        "rollback": rollback,
+        "tree_nets": tree_nets,
+        "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,
+        "via_cost": via_cost,
+    }
+    started = time.monotonic()
    exact = route_board_exact(
        board,
        resolution=resolution,
-        heuristic_weight=heuristic_weight,
-        via_half=_via_half_board(dsn, scale),
-        edge_clearance=edge_clearance_board,
-        trace_width=width_board,
-        clearance=clearance_board,
-        layers=layers,
-        max_passes=max_passes,
-        rip_up=rip_up,
-        shove=shove,
-        diagonal=diagonal,
        seed=seed,
        route_first=route_first,
        access_cost=access_cost,
        negotiate=negotiate,
-        rollback=rollback,
-        tree_nets=tree_nets,
-        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,
+        **common,
    )
+    if window_reroute > 0:
+        via_half = common["via_half"] or max(width_board // 2, 1)
+        exact.result = window_reroute_stage(
+            dsn, exact.result, common,
+            rounds=window_reroute,
+            resolution=max(int(window_resolution), resolution),
+            margin=_mm_to_board(dsn, scale, window_margin_mm) or 0,
+            via_half=via_half,
+            via_drill=common["via_drill"] or 2 * via_half,
+            via_name=_via_padstack(dsn),
+            # a share of what the routing itself took
+            budget_s=max(float(window_budget), 0.0) * (time.monotonic() - started),
+            max_windows=window_cap,
+        )
+    if reduce_vias:
+        via_half = common["via_half"] or max(width_board // 2, 1)
+        exact.result = reduce_vias_stage(
+            dsn, exact.result, common,
+            resolution=resolution,
+            margin=_mm_to_board(dsn, scale, reduce_vias_margin_mm) or 0,
+            via_half=via_half,
+            via_drill=common["via_drill"] or 2 * via_half,
+            via_name=_via_padstack(dsn),
+            # a share of what the routing itself took
+            budget_s=max(float(reduce_vias_budget), 0.0) * (time.monotonic() - started),
+        )
    return exact, scale, [layer.name for layer in dsn.layers]


@@ -292,6 +340,15 @@ def build_exact_routing_result(
    hole_to_hole_mm: float = 0.25,
    rollback: bool = True,
    tree_nets: bool = True,
+    window_reroute: int = 0,
+    window_resolution: int = 4,
+    window_margin_mm: float = 1.5,
+    window_budget: float = 0.25,
+    window_cap: int = 40,
+    reduce_vias: bool = False,
+    reduce_vias_budget: float = 0.5,
+    reduce_vias_margin_mm: float = 2.0,
+    via_cost: float = 10.0,
 ) -> RoutingResult:
    """Route ``dsn`` (exact track) and convert to a DSN-unit RoutingResult."""
    exact, scale, layer_names = route_dsn_board_exact(
@@ -311,6 +368,15 @@ def build_exact_routing_result(
        hole_to_hole_mm=hole_to_hole_mm,
        rollback=rollback,
        tree_nets=tree_nets,
+        window_reroute=window_reroute,
+        window_resolution=window_resolution,
+        window_margin_mm=window_margin_mm,
+        window_budget=window_budget,
+        window_cap=window_cap,
+        reduce_vias=reduce_vias,
+        reduce_vias_budget=reduce_vias_budget,
+        reduce_vias_margin_mm=reduce_vias_margin_mm,
+        via_cost=via_cost,
    )
    return _to_routing_result(exact.result, dsn, scale, layer_names)

@@ -30,10 +30,10 @@ from __future__ import annotations
 from dataclasses import dataclass, field
 import heapq

-from freeroute.board.board import BasicBoard
-from freeroute.board.items import Pin
-from freeroute.board.search_tree import ShapeSearchTree, TreeShape
-from freeroute.geometry import IntBox, IntPoint, Polyline, PolylineShape, shove_segment
+from rpmroute.board.board import BasicBoard
+from rpmroute.board.items import Pin
+from rpmroute.board.search_tree import ShapeSearchTree, TreeShape
+from rpmroute.geometry import IntBox, IntPoint, Polyline, PolylineShape, shove_segment

 from .exact_router import ExactRouteResult, _routable_nets
 from .grid_router import RouteResult
@@ -56,7 +56,7 @@ class _Accepted:
    ``wires`` / ``vias`` are the *same* list objects as ``RouteResult.wires`` /
    ``.vias`` for this net, so rewriting a shoved wire in place also updates the
    routed output. ``wire_owners`` is parallel to ``wires``: each entry is the
-    list of :class:`~freeroute.board.search_tree.TreeShape` owner ids for that
+    list of :class:`~rpmroute.board.search_tree.TreeShape` owner ids for that
    wire's copper tiles, so a later shove can locate, remove, and roll back a
    specific wire without disturbing a multi-wire net's other connections.
    """
@@ -1,6 +1,6 @@
 """Shared orthogonal shove primitives for the exact and room routers.

-The exact-geometry router (:mod:`freeroute.route.exact_router`) grew the first
+The exact-geometry router (:mod:`rpmroute.route.exact_router`) grew the first
 shove implementation; the continuous room router reuses its geometry so both
 tracks agree on how a blocking trace's conflicting segment is found, how the
 perpendicular displacement ladder is generated, and how a reshaped trace is
@@ -19,8 +19,8 @@ from __future__ import annotations

 from collections.abc import Iterator

-from freeroute.board.search_tree import ShapeSearchTree, TreeShape
-from freeroute.geometry import IntBox, IntPoint, Polyline, PolylineShape
+from rpmroute.board.search_tree import ShapeSearchTree, TreeShape
+from rpmroute.geometry import IntBox, IntPoint, Polyline, PolylineShape

 from .exact_router import _conflicting_segment as conflicting_segment

@@ -0,0 +1,542 @@
+"""Smoothing: a last stage that turns grid staircases into octilinear runs.
+
+The grid search moves one cell at a time along the axes, so a route that
+heads off at an angle comes out as a staircase of short legs. Nothing goes
+back over a path once it connects. This stage does, wire by wire, on the
+finished result:
+
+1. a run of legs between two of its points is replaced by the octilinear
+   shape joining them (one straight leg, or a straight leg and a 45-degree
+   one), the furthest such point first;
+2. the right-angle corners left are cut to 45-degree chamfers;
+3. legs running on in the same direction are merged.
+
+Same nets, same layers, same vias. A wire keeps its ends, every via of its
+net, every point where another wire of its net ends on it, and any leg
+across a pad of its own net that it does not end on; only what lies between
+those moves. Every new leg and corner is checked against the other nets'
+copper, pads and keepouts on the exact shapes the exact engine uses, and
+against the board edge; a wire is changed only when all of its new copper
+is clear. Fixed wiring from the DSN is not part of the result and is never
+touched; it is checked against like any other copper.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+import itertools
+import math
+
+from rpmroute.board import build_board
+from rpmroute.board.search_tree import ShapeSearchTree, TreeShape
+from rpmroute.dsn.model import DsnBoard
+from rpmroute.geometry import IntBox, IntPoint, overlaps_2d, segment_box, segment_slab
+from rpmroute.geometry.polyline import corner_box
+from rpmroute.ses.model import RoutingResult
+
+from .exact_router import insert_static_copper
+from .pipeline import _dsn_units_per_um, _mm_to_board, _rule_clearance_dsn, _via_half_board
+
+#: how many points ahead a staircase collapse looks from each point
+LOOKAHEAD = 64
+#: a 45-degree leg at least this many track widths long: a shorter one is a
+#: kink beside its end's pad, where a refilled pour leaves a copper sliver
+MIN_DIAGONAL_WIDTHS = 2
+
+
+@dataclass
+class Shape:
+    """What a set of wires looks like: legs, right-angle corners, length."""
+
+    segments: int = 0
+    right_angles: int = 0
+    length_mm: dict[str, float] = field(default_factory=dict)
+
+    @property
+    def total_mm(self) -> float:
+        return sum(self.length_mm.values())
+
+
+@dataclass
+class SmoothReport:
+    before: Shape
+    after: Shape
+    wires_changed: int = 0
+    wires: int = 0
+    #: True when the finished check found more violations than before and
+    #: the smoothing was thrown away (never expected; a guard)
+    reverted: bool = False
+
+    def line(self) -> str:
+        b, a = self.before, self.after
+        if self.reverted:
+            return "smoothing reverted: it would have added a clearance violation"
+        return (
+            f"smoothed {self.wires_changed} of {self.wires} wires: segments {b.segments} -> "
+            f"{a.segments}, right-angle corners {b.right_angles} -> {a.right_angles}, "
+            f"length {b.total_mm:.1f} -> {a.total_mm:.1f} mm"
+        )
+
+    def table(self) -> list[str]:
+        rows = [f"  {'layer':10} {'before mm':>10} {'after mm':>10}"]
+        for layer in sorted(set(self.before.length_mm) | set(self.after.length_mm)):
+            rows.append(
+                f"  {layer:10} {self.before.length_mm.get(layer, 0.0):>10.1f} "
+                f"{self.after.length_mm.get(layer, 0.0):>10.1f}"
+            )
+        return rows
+
+
+def _shape_of(wires, mm_per_unit: float) -> Shape:
+    """``wires``: (layer name, points) pairs in board units."""
+    out = Shape()
+    for layer, pts in wires:
+        out.segments += max(len(pts) - 1, 0)
+        out.length_mm[layer] = out.length_mm.get(layer, 0.0) + mm_per_unit * sum(
+            math.hypot(q.x - p.x, q.y - p.y) for p, q in zip(pts, pts[1:], strict=False)
+        )
+        for a, b, c in zip(pts, pts[1:], pts[2:], strict=False):
+            if (b.x - a.x) * (c.x - b.x) + (b.y - a.y) * (c.y - b.y) == 0:
+                out.right_angles += 1
+    return out
+
+
+def _sign(v: int) -> int:
+    return (v > 0) - (v < 0)
+
+
+def _octilinear(a: IntPoint, b: IntPoint) -> bool:
+    dx, dy = b.x - a.x, b.y - a.y
+    return dx == 0 or dy == 0 or abs(dx) == abs(dy)
+
+
+def _candidates(a: IntPoint, b: IntPoint) -> list[list[IntPoint]]:
+    """The octilinear ways from ``a`` to ``b``: straight when the two lie on
+    an axis or a diagonal, else the 45-degree leg first or last."""
+    if _octilinear(a, b):
+        return [[a, b]]
+    dx, dy = b.x - a.x, b.y - a.y
+    m = min(abs(dx), abs(dy))
+    sx, sy = _sign(dx), _sign(dy)
+    return [
+        [a, IntPoint(a.x + sx * m, a.y + sy * m), b],
+        [a, IntPoint(b.x - sx * m, b.y - sy * m), b],
+    ]
+
+
+def _too_short(a: IntPoint, b: IntPoint, half: int) -> bool:
+    """A slanted leg shorter than MIN_DIAGONAL_WIDTHS track widths."""
+    if a.x == b.x or a.y == b.y:
+        return False
+    return (b.x - a.x) ** 2 + (b.y - a.y) ** 2 < (MIN_DIAGONAL_WIDTHS * 2 * half) ** 2
+
+
+def _dedupe(pts: list[IntPoint]) -> list[IntPoint]:
+    out: list[IntPoint] = []
+    for p in pts:
+        if not out or (out[-1].x, out[-1].y) != (p.x, p.y):
+            out.append(p)
+    return out
+
+
+def _merge_collinear(pts: list[IntPoint], keep: set[tuple[int, int]]) -> list[IntPoint]:
+    """Drop points where the wire runs straight on, except the ones in ``keep``."""
+    pts = _dedupe(pts)
+    out = pts[:1]
+    for i in range(1, len(pts) - 1):
+        a, b, c = out[-1], pts[i], pts[i + 1]
+        straight = (b.x - a.x) * (c.y - b.y) - (b.y - a.y) * (c.x - b.x) == 0 and (
+            (b.x - a.x) * (c.x - b.x) + (b.y - a.y) * (c.y - b.y) > 0
+        )
+        if straight and (b.x, b.y) not in keep:
+            continue
+        out.append(b)
+    if len(pts) > 1:
+        out.append(pts[-1])
+    return out
+
+
+def _on_segment(p: IntPoint, a: IntPoint, b: IntPoint, reach: int) -> IntPoint | None:
+    """The point of axis leg ``a``-``b`` within ``reach`` of ``p`` (across the
+    leg), or None. Slanted legs only count ``p`` that lies exactly on them."""
+    if a.x == b.x:
+        lo, hi = sorted((a.y, b.y))
+        if abs(p.x - a.x) <= reach and lo <= p.y <= hi:
+            return IntPoint(a.x, p.y)
+        return None
+    if a.y == b.y:
+        lo, hi = sorted((a.x, b.x))
+        if abs(p.y - a.y) <= reach and lo <= p.x <= hi:
+            return IntPoint(p.x, a.y)
+        return None
+    cross = (b.x - a.x) * (p.y - a.y) - (b.y - a.y) * (p.x - a.x)
+    within = min(a.x, b.x) <= p.x <= max(a.x, b.x) and min(a.y, b.y) <= p.y <= max(a.y, b.y)
+    return IntPoint(p.x, p.y) if cross == 0 and within else None
+
+
+class _Smoother:
+    def __init__(self, tree, outline, edge: int, clearance: int) -> None:
+        self.tree = tree
+        self.outline = outline
+        self.edge = edge
+        self.clearance = clearance
+
+    def _inside(self, box: IntBox) -> bool:
+        return self.outline is None or self.outline.box_clear(box, self.edge)
+
+    def leg_clear(self, a: IntPoint, b: IntPoint, half: int, net: int, layer: int) -> bool:
+        if a.x == b.x or a.y == b.y:
+            box = segment_box(a, b, half)
+            return self._inside(box) and not self.tree.clearance_conflict(
+                box, net, layer, self.clearance
+            )
+        copper = segment_slab(a, b, half)
+        if not self._inside(copper.bounding_box()):
+            return False
+        # Both ways round, as the finished check counts a pair: this leg's
+        # copper grown by the clearance against the other's copper, and the
+        # other's clearance region (a box grown square, so wider at its
+        # corners) against this leg's copper.
+        grown = segment_slab(a, b, half + self.clearance)
+        for shape in self.tree.overlapping(copper.bounding_box().offset(self.clearance)):
+            if shape.net_no == net or not shape.on_layer(layer):
+                continue
+            if shape.blocks not in ("all", "wires"):
+                continue
+            theirs = shape.exact if shape.exact is not None else shape.tile
+            if not shape.clearance:
+                if overlaps_2d(copper, theirs):
+                    return False
+            elif overlaps_2d(grown, theirs) or overlaps_2d(
+                shape.clearance_region(self.clearance), copper
+            ):
+                return False
+        return True
+
+    def corner_clear(self, c: IntPoint, half: int, net: int, layer: int) -> bool:
+        box = corner_box(c, half)
+        return self._inside(box) and not self.tree.clearance_conflict(
+            box, net, layer, self.clearance
+        )
+
+    def path_clear(self, path: list[IntPoint], half: int, net: int, layer: int) -> bool:
+        """New legs and new corners of ``path`` (its ends are kept points)."""
+        if any(_too_short(p, q, half) for p, q in zip(path, path[1:], strict=False)):
+            return False
+        return all(
+            self.leg_clear(p, q, half, net, layer) for p, q in zip(path, path[1:], strict=False)
+        ) and all(self.corner_clear(c, half, net, layer) for c in path[1:-1])
+
+    def collapse(self, pts: list[IntPoint], half: int, net: int, layer: int) -> list[IntPoint]:
+        """Step 1 on one section (both ends kept): from each point, jump to
+        the furthest later point an octilinear path reaches cleanly."""
+        out = [pts[0]]
+        i, n = 0, len(pts)
+        while i < n - 1:
+            jumped = False
+            for j in range(min(n - 1, i + LOOKAHEAD), i + 1, -1):
+                for path in _candidates(pts[i], pts[j]):
+                    if self.path_clear(path, half, net, layer):
+                        out.extend(path[1:])
+                        i, jumped = j, True
+                        break
+                if jumped:
+                    break
+            if not jumped:
+                out.append(pts[i + 1])
+                i += 1
+        return out
+
+    def miter(
+        self, pts: list[IntPoint], half: int, net: int, layer: int, keep: set[tuple[int, int]]
+    ) -> list[IntPoint]:
+        """Step 2: cut each right-angle corner between two axis legs to a
+        45-degree chamfer, as long a one as fits, at least a track width."""
+        pts = list(pts)
+        i = 1
+        while i < len(pts) - 1:
+            a, c, b = pts[i - 1], pts[i], pts[i + 1]
+            if (c.x, c.y) in keep or not (
+                (a.x == c.x or a.y == c.y) and (c.x == b.x or c.y == b.y)
+            ):
+                i += 1
+                continue
+            ux, uy = _sign(c.x - a.x), _sign(c.y - a.y)
+            vx, vy = _sign(b.x - c.x), _sign(b.y - c.y)
+            if ux * vx + uy * vy != 0:
+                i += 1
+                continue
+            len_in = abs(c.x - a.x) + abs(c.y - a.y)
+            len_out = abs(b.x - c.x) + abs(b.y - c.y)
+            # leave half of a leg for the corner at its other end, unless that
+            # end stays where it is anyway
+            cap_in = len_in if (a.x, a.y) in keep or i == 1 else len_in // 2
+            cap_out = len_out if (b.x, b.y) in keep or i == len(pts) - 2 else len_out // 2
+            d = min(cap_in, cap_out)
+            done = False
+            # the chamfer's leg is d * sqrt(2) long
+            while d * d * 2 >= (MIN_DIAGONAL_WIDTHS * 2 * half) ** 2:
+                p = IntPoint(c.x - ux * d, c.y - uy * d)
+                q = IntPoint(c.x + vx * d, c.y + vy * d)
+                corners = [x for x in (p, q) if (x.x, x.y) not in ((a.x, a.y), (b.x, b.y))]
+                if self.leg_clear(p, q, half, net, layer) and all(
+                    self.corner_clear(x, half, net, layer) for x in corners
+                ):
+                    pts[i : i + 1] = [p, q]
+                    pts = _dedupe(pts)
+                    done = True
+                    break
+                d = d * 3 // 4 if d * 3 // 4 < d else d - 1
+            i += 2 if done else 1
+        return pts
+
+
+def smooth(
+    dsn: DsnBoard, result: RoutingResult, *, edge_clearance_mm: float | None = None
+) -> SmoothReport:
+    """Smooth ``result``'s wires in place; return what changed."""
+    board = build_board(dsn)
+    scale = max(dsn.resolution.value, 1)
+    clearance = round(_rule_clearance_dsn(dsn) * scale)
+    edge = _mm_to_board(dsn, scale, edge_clearance_mm) or 0
+    mm_per_unit = 1 / (_dsn_units_per_um(dsn) * 1000 * scale)
+    signal_layers = [i for i, layer in enumerate(dsn.layers) if layer.is_signal]
+    layer_index = {layer.name: i for i, layer in enumerate(dsn.layers)}
+    via_layers = frozenset(signal_layers)
+    net_numbers = {n.name: i + 1 for i, n in enumerate(dsn.nets)}
+    via_half = _via_half_board(dsn, scale)
+
+    tree = ShapeSearchTree()
+    owner = itertools.count(1)
+    insert_static_copper(tree, board, signal_layers, owner)
+
+    def to_points(wire) -> list[IntPoint]:
+        c = wire.coords
+        return [IntPoint(round(c[i] * scale), round(c[i + 1] * scale)) for i in range(0, len(c) - 1, 2)]
+
+    # own-net pads per (net, layer): legs across one the wire does not end on stay
+    pads: dict[tuple[int, int], list[IntBox]] = {}
+    for pin in board.get_pins():
+        if pin.shape is None or not pin.net_nos:
+            continue
+        box = pin.shape.bounding_box()
+        for layer in pin.layers:
+            pads.setdefault((pin.net_nos[0], layer), []).append(box)
+
+    # every routed wire and via into the tree, each wire under owners of its own
+    wires: list[tuple[int, object, int, int, list[IntPoint], list[int]]] = []
+    for net in result.nets:
+        net_no = net_numbers.get(net.name)
+        if net_no is None:
+            continue
+        for wire in net.wires:
+            layer = layer_index.get(wire.layer)
+            if layer is None or layer not in signal_layers or wire.fixed:
+                continue
+            half = max(round(wire.width * scale / 2), 1)
+            pts = to_points(wire)
+            wires.append((net_no, wire, layer, half, pts, _insert(tree, owner, pts, half, net_no, layer)))
+        for via in net.vias:
+            vh = via_half or max(round(max((w.width for w in net.wires), default=0) * scale / 2), 1)
+            x, y = round(via.x * scale), round(via.y * scale)
+            tree.insert(TreeShape(
+                next(owner), net_no, via_layers, IntBox(x - vh, y - vh, x + vh, y + vh), routed=True,
+            ))
+
+    before_pairs = len(tree.violation_pairs(clearance))
+    before = _shape_of(
+        [(dsn.layers[w[2]].name, w[4]) for w in wires], mm_per_unit
+    )
+
+    # the points of each net another of its wires or a via meets
+    joints: dict[int, list[IntPoint]] = {}
+    for net in result.nets:
+        net_no = net_numbers.get(net.name)
+        if net_no is None:
+            continue
+        for via in net.vias:
+            joints.setdefault(net_no, []).append(IntPoint(round(via.x * scale), round(via.y * scale)))
+    for net_no, _wire, _layer, _half, pts, _owners in wires:
+        joints.setdefault(net_no, []).extend((pts[0], pts[-1]))
+
+    pins_of: dict[int, list] = {}
+    for pin in board.get_pins():
+        if pin.shape is not None and pin.net_nos:
+            pins_of.setdefault(pin.net_nos[0], []).append(pin)
+    vias_of = {
+        net_numbers[net.name]: [IntPoint(round(v.x * scale), round(v.y * scale)) for v in net.vias]
+        for net in result.nets
+        if net.name in net_numbers
+    }
+    by_net: dict[int, list[int]] = {}
+    for k, w in enumerate(wires):
+        by_net.setdefault(w[0], []).append(k)
+
+    smoother = _Smoother(tree, board.outline, edge, clearance)
+    changed = 0
+    originals = []
+    for net_no, ks in by_net.items():
+        groups_before = _pad_groups(
+            [wires[k] for k in ks], pins_of.get(net_no, []), vias_of.get(net_no, [])
+        )
+        undo = []
+        for k in ks:
+            _, wire, layer, half, pts, owners = wires[k]
+            if len(pts) < 3:
+                continue
+            keep_pts, keep = _kept_points(
+                pts, joints.get(net_no, []), half, pads.get((net_no, layer), [])
+            )
+            new = _merge_collinear(keep_pts, keep)
+            out: list[IntPoint] = [new[0]]
+            start = 0
+            for i in range(1, len(new)):
+                if (new[i].x, new[i].y) in keep or i == len(new) - 1:
+                    section = smoother.collapse(new[start : i + 1], half, net_no, layer)
+                    out.extend(section[1:])
+                    start = i
+            out = smoother.miter(_merge_collinear(out, keep), half, net_no, layer, keep)
+            out = _merge_collinear(out, keep)
+            if [(p.x, p.y) for p in out] == [(p.x, p.y) for p in pts]:
+                continue
+            # the wire's own old copper is the same net and never in the way,
+            # so it can go once the new copper is in
+            for oid in owners:
+                tree.remove_owner(oid)
+            new_owners = _insert(tree, owner, out, half, net_no, layer)
+            undo.append((k, wires[k], list(wire.coords)))
+            wire.coords = [v / scale for p in out for v in (p.x, p.y)]
+            wires[k] = (net_no, wire, layer, half, out, new_owners)
+        if not undo:
+            continue
+        groups_after = _pad_groups(
+            [wires[k] for k in ks], pins_of.get(net_no, []), vias_of.get(net_no, [])
+        )
+        if groups_after != groups_before:
+            # a pad lost (or gained) its way to the rest of the net: keep the
+            # net as it was routed
+            for k, old, coords in reversed(undo):
+                for oid in wires[k][5]:
+                    tree.remove_owner(oid)
+                old[1].coords = coords
+                wires[k] = (*old[:5], _insert(tree, owner, old[4], old[3], net_no, old[2]))
+            continue
+        originals.extend((old[1], coords) for _k, old, coords in undo)
+        changed += len(undo)
+
+    report = SmoothReport(
+        before=before,
+        after=_shape_of([(dsn.layers[w[2]].name, w[4]) for w in wires], mm_per_unit),
+        wires_changed=changed,
+        wires=len(wires),
+    )
+    if changed and len(tree.violation_pairs(clearance)) > before_pairs:
+        for wire, coords in originals:
+            wire.coords = coords
+        report.after, report.wires_changed, report.reverted = before, 0, True
+    return report
+
+
+def _insert(tree, owner, pts, half, net_no, layer) -> list[int]:
+    """A wire's copper into ``tree`` as the exact engine models it: legs (on
+    their exact slab when slanted) and a square at each inner corner."""
+    on = frozenset({layer})
+    owners = []
+    for a, b in zip(pts, pts[1:], strict=False):
+        oid = next(owner)
+        if a.x == b.x or a.y == b.y:
+            tree.insert(TreeShape(oid, net_no, on, segment_box(a, b, half), routed=True))
+        else:
+            slab = segment_slab(a, b, half)
+            tree.insert(TreeShape(
+                oid, net_no, on, slab.bounding_box(), routed=True, exact=slab, seg=("slab", a, b, half),
+            ))
+        owners.append(oid)
+    for c in pts[1:-1]:
+        oid = next(owner)
+        tree.insert(TreeShape(oid, net_no, on, corner_box(c, half), routed=True))
+        owners.append(oid)
+    return owners
+
+
+def _kept_points(
+    pts: list[IntPoint], joints: list[IntPoint], half: int, own_pads: list[IntBox]
+) -> tuple[list[IntPoint], set[tuple[int, int]]]:
+    """The wire with a point added wherever another wire of its net or a via
+    meets it, and the set of points that must stay: those, its ends, and the
+    ends of any leg across an own-net pad it does not end on."""
+    keep = {(pts[0].x, pts[0].y), (pts[-1].x, pts[-1].y)}
+    out = [pts[0]]
+    for a, b in zip(pts, pts[1:], strict=False):
+        hits = []
+        for j in joints:
+            p = _on_segment(j, a, b, half)
+            if p is not None:
+                hits.append(p)
+                keep.add((p.x, p.y))
+        hits.sort(key=lambda p: abs(p.x - a.x) + abs(p.y - a.y))
+        out.extend(h for h in hits if (h.x, h.y) not in ((a.x, a.y), (b.x, b.y)))
+        out.append(b)
+    end_pads = [box for box in own_pads if _in(pts[0], box) or _in(pts[-1], box)]
+    for box in own_pads:
+        if any(box is e for e in end_pads):
+            continue
+        for a, b in zip(out, out[1:], strict=False):
+            if segment_box(a, b, 0).overlaps(box):
+                keep.add((a.x, a.y))
+                keep.add((b.x, b.y))
+    return _dedupe(out), keep
+
+
+def _near(p: IntPoint, pts: list[IntPoint], reach: int) -> bool:
+    """Whether ``p`` lies on the copper of the wire through ``pts`` (``reach``
+    its half width), squared at the corners as the copper is modelled."""
+    for a, b in zip(pts, pts[1:], strict=False):
+        dx, dy = b.x - a.x, b.y - a.y
+        n2 = dx * dx + dy * dy
+        t = 0.0 if n2 == 0 else max(0.0, min(1.0, ((p.x - a.x) * dx + (p.y - a.y) * dy) / n2))
+        cx, cy = a.x + t * dx, a.y + t * dy
+        if math.hypot(p.x - cx, p.y - cy) <= reach + 1:
+            return True
+    return False
+
+
+def _pad_groups(wires, pins, vias) -> set[frozenset[int]]:
+    """Which of a net's pads its copper joins, as groups of pad indices: a
+    wire's end on a pad, on another wire, or on a via; a via on a pad."""
+    parent = list(range(len(pins) + len(wires) + len(vias)))
+
+    def find(x: int) -> int:
+        while parent[x] != x:
+            parent[x] = parent[parent[x]]
+            x = parent[x]
+        return x
+
+    def join(x: int, y: int) -> None:
+        parent[find(x)] = find(y)
+
+    boxes = [p.shape.bounding_box() for p in pins]
+    w0, v0 = len(pins), len(pins) + len(wires)
+    for i, (_n, _w, layer, half, pts, _o) in enumerate(wires):
+        for end in (pts[0], pts[-1]):
+            for j, pin in enumerate(pins):
+                if layer in pin.layers and _in(end, boxes[j]):
+                    join(w0 + i, j)
+            for k, (_n2, _w2, layer2, half2, pts2, _o2) in enumerate(wires):
+                if k != i and layer2 == layer and _near(end, pts2, half2):
+                    join(w0 + i, w0 + k)
+            for v, loc in enumerate(vias):
+                if (end.x, end.y) == (loc.x, loc.y) or _near(loc, pts, half):
+                    join(w0 + i, v0 + v)
+    for v, loc in enumerate(vias):
+        for j in range(len(pins)):
+            if _in(loc, boxes[j]):
+                join(v0 + v, j)
+    groups: dict[int, set[int]] = {}
+    for j in range(len(pins)):
+        groups.setdefault(find(j), set()).add(j)
+    return {frozenset(g) for g in groups.values()}
+
+
+def _in(p: IntPoint, box: IntBox) -> bool:
+    return box.ll.x <= p.x <= box.ur.x and box.ll.y <= p.y <= box.ur.y
@@ -0,0 +1,151 @@
+"""Check routed copper that no engine has checked.
+
+The exact engine verifies every connection against exact pad and copper
+shapes before it accepts it. The grid and room engines do not: they route on
+approximations, and their output can short or crowd another net with nothing
+in their report to say so. :func:`verify_result` puts a finished
+:class:`RoutingResult` through the same exact geometry the exact engine uses
+(its pads, fixed copper and keepouts, wires as boxes or slanted slabs, vias as
+their pads) and lists what it finds.
+
+A violation is a pair of different-net coppers on a shared layer, at least one
+of them routed, closer than the board's clearance rule. It is a short when the
+coppers themselves overlap (or routed copper sits inside a keepout), else a
+clearance violation. Pairs are counted per routed segment or via, as KiCad's
+DRC counts per item pair; pads already too close to each other in the design
+are not the router's and are not counted.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+import itertools
+
+from rpmroute.board import build_board
+from rpmroute.board.search_tree import ShapeSearchTree, TreeShape
+from rpmroute.dsn.model import DsnBoard
+from rpmroute.geometry import IntBox, IntPoint, segment_box, segment_slab
+from rpmroute.geometry.polyline import corner_box
+from rpmroute.ses.model import RoutingResult
+
+from .exact_router import insert_static_copper
+from .pipeline import _dsn_units_per_um, _rule_clearance_dsn, _via_half_board
+
+# examples kept per kind; the counts are always complete
+MAX_EXAMPLES = 5
+
+
+@dataclass
+class Violation:
+    """One offending pair: the routed copper's net, what it came too close
+    to, the layer, and roughly where (mm, DSN coordinates)."""
+
+    net: str
+    other: str
+    layer: str
+    x_mm: float
+    y_mm: float
+
+    def __str__(self) -> str:
+        return f"{self.net} x {self.other} on {self.layer} at ({self.x_mm:.2f}, {self.y_mm:.2f}) mm"
+
+
+@dataclass
+class VerifyReport:
+    shorts: int = 0
+    clearance: int = 0
+    short_examples: list[Violation] = field(default_factory=list)
+    clearance_examples: list[Violation] = field(default_factory=list)
+
+    @property
+    def clean(self) -> bool:
+        return not (self.shorts or self.clearance)
+
+
+def verify_result(dsn: DsnBoard, result: RoutingResult) -> VerifyReport:
+    """Check ``result``'s copper against ``dsn``'s pads, keepouts and each
+    other, with the board's clearance rule."""
+    board = build_board(dsn)
+    scale = max(dsn.resolution.value, 1)
+    clearance = round(_rule_clearance_dsn(dsn) * scale)
+    signal_layers = [i for i, layer in enumerate(dsn.layers) if layer.is_signal]
+    layer_index = {layer.name: i for i, layer in enumerate(dsn.layers)}
+    via_layers = frozenset(signal_layers)
+    net_numbers = {n.name: i + 1 for i, n in enumerate(dsn.nets)}
+    names = {number: name for name, number in net_numbers.items()}
+
+    tree = ShapeSearchTree()
+    owner = itertools.count(1)
+    insert_static_copper(tree, board, signal_layers, owner)
+    static_names: dict[int, str] = {}
+    for shape in tree.all_shapes():
+        static_names[shape.owner] = "keepout" if shape.net_no == -1 else f"pad of {names.get(shape.net_no, '?')}"
+
+    via_default = _via_half_board(dsn, scale)
+    for net in result.nets:
+        net_no = net_numbers.get(net.name)
+        if net_no is None:
+            continue
+        for wire in net.wires:
+            layer = layer_index.get(wire.layer)
+            if layer is None or layer not in signal_layers:
+                continue
+            half = max(round(wire.width * scale / 2), 1)
+            pts = [
+                IntPoint(round(wire.coords[i] * scale), round(wire.coords[i + 1] * scale))
+                for i in range(0, len(wire.coords) - 1, 2)
+            ]
+            on = frozenset({layer})
+            for a, b in zip(pts, pts[1:], strict=False):
+                oid = next(owner)
+                if a.x == b.x or a.y == b.y:
+                    tree.insert(TreeShape(oid, net_no, on, segment_box(a, b, half), routed=True))
+                else:  # a 45-degree or slanted segment, on its exact copper
+                    slab = segment_slab(a, b, half)
+                    tree.insert(TreeShape(
+                        oid, net_no, on, slab.bounding_box(), routed=True,
+                        exact=slab, seg=("slab", a, b, half),
+                    ))
+                # the round end where it meets the next segment, with this one
+                tree.insert(TreeShape(oid, net_no, on, corner_box(b, half), routed=True))
+        for via in net.vias:
+            half = via_default or max(round(_wire_width(net) * scale / 2), 1)
+            x, y = round(via.x * scale), round(via.y * scale)
+            tree.insert(TreeShape(
+                next(owner), net_no, via_layers, IntBox(x - half, y - half, x + half, y + half), routed=True,
+            ))
+
+    mm_per_unit = 1 / (_dsn_units_per_um(dsn) * 1000 * scale)
+    # one entry per pair of items, however many of their tiles meet; a short
+    # if any of them overlap
+    by_pair: dict[tuple[int, int], tuple[TreeShape, TreeShape, bool]] = {}
+    for shape, other, touching in tree.violation_pairs(clearance):
+        key = (min(shape.owner, other.owner), max(shape.owner, other.owner))
+        seen = by_pair.get(key)
+        if seen is None or (touching and not seen[2]):
+            by_pair[key] = (shape, other, touching)
+
+    report = VerifyReport()
+    for shape, other, touching in by_pair.values():
+        layer = min(shape.layers & other.layers)
+        box = shape.tile.intersection(other.tile.offset(clearance))
+        if box.is_empty():
+            box = shape.tile
+        what = names.get(other.net_no, "?") if other.routed else static_names.get(other.owner, "?")
+        found = Violation(
+            names.get(shape.net_no, "?"), what, dsn.layers[layer].name,
+            (box.ll.x + box.ur.x) / 2 * mm_per_unit, (box.ll.y + box.ur.y) / 2 * mm_per_unit,
+        )
+        if touching:
+            report.shorts += 1
+            if len(report.short_examples) < MAX_EXAMPLES:
+                report.short_examples.append(found)
+        else:
+            report.clearance += 1
+            if len(report.clearance_examples) < MAX_EXAMPLES:
+                report.clearance_examples.append(found)
+    return report
+
+
+def _wire_width(net) -> float:
+    return max((w.width for w in net.wires), default=0.0)
@@ -0,0 +1,128 @@
+"""Via reduction: a last stage that routes each net again with vias made dear.
+
+The main search prices a layer change at a few millimetres of track, which
+is right while the board is crowded and wrong once it is routed: a net that
+hopped layers to slip past a route can often stay on one layer around it.
+So each net that has vias is ripped and routed again on its own, everything
+else held as fixed copper, with the via cost raised; the new copper is kept
+only if the net loses no connection and ends with fewer vias.
+
+It reuses the window stage's board: the net's own items and copper, and of
+everything else only what lies near the box the net is routed in. The nets
+with the most vias go first, and no new net starts once ``budget_s`` is
+spent.
+"""
+
+from __future__ import annotations
+
+import time
+from typing import Any
+
+from rpmroute.board import build_board
+from rpmroute.dsn import DsnBoard
+from rpmroute.geometry import IntBox
+
+from .exact_router import route_board_exact
+from .grid_router import RouteResult
+from .window import Copper, _inside, _item_box, _open, _window_board
+
+
+def _net_box(copper: Copper, pins: list, grow: int) -> IntBox | None:
+    wires, vias = copper
+    points = [p for _layer, path in wires for p in path] + list(vias) + pins
+    if not points:
+        return None
+    xs, ys = [p.x for p in points], [p.y for p in points]
+    return IntBox(min(xs) - grow, min(ys) - grow, max(xs) + grow, max(ys) + grow)
+
+
+def reduce_vias(
+    dsn: DsnBoard,
+    result: RouteResult,
+    route_args: dict[str, Any],
+    *,
+    resolution: int,
+    margin: int,
+    via_half: int,
+    via_drill: int,
+    via_name: str,
+    via_cost_factor: float = 8.0,
+    budget_s: float | None = None,
+) -> RouteResult:
+    """Route each net with vias again with vias ``via_cost_factor`` times dearer;
+    keep a net's new copper only when it fails nothing new and has fewer vias.
+
+    ``route_args`` are the exact engine's settings for the whole board.
+    ``margin`` grows the box around the net's pins and copper that it is
+    routed in, so it may go round what it used to hop over."""
+    started = time.monotonic()
+    copper: dict[int, Copper] = {
+        net: (list(result.wires.get(net, [])), list(result.vias.get(net, [])))
+        for net in set(result.wires) | set(result.vias)
+    }
+    todo = sorted((n for n, c in copper.items() if c[1]), key=lambda n: -len(set(copper[n][1])))
+    if not todo:
+        return result
+    default_half = result.half_width
+    half = dict(result.net_half)
+    failed = list(result.failed)
+    base = build_board(dsn)
+    base_items = [(item, _item_box(item)) for item in base.get_items()]
+    layers = route_args.get("layers") or [
+        i for i, layer in enumerate(base.layer_structure.arr) if layer.is_signal
+    ]
+    pins_of: dict[int, list] = {}
+    for pin in base.get_pins():
+        for net in pin.net_nos:
+            pins_of.setdefault(net, []).append(pin.location)
+    context = 2 * (route_args["trace_width"] + route_args["clearance"]) + 2 * via_half + (
+        route_args.get("edge_clearance") or 0
+    )
+    args = dict(route_args)
+    args["via_cost"] = float(route_args.get("via_cost", 10.0)) * via_cost_factor
+
+    changed = False
+    for net in todo:
+        if budget_s is not None and time.monotonic() - started >= budget_s:
+            break
+        old_vias = len(set(copper[net][1]))
+        window = _net_box(copper[net], pins_of.get(net, []), margin)
+        if window is None:
+            continue
+        before = _open(f for f in failed if f[0] == net)
+        view = IntBox(window.ll.x - context, window.ll.y - context,
+                      window.ur.x + context, window.ur.y + context)
+        keep = set(copper) - {net}
+        board = _window_board(base, base_items, view, {net}, copper, keep, half,
+                              default_half, via_half, via_drill, layers, via_name)
+        sub = route_board_exact(
+            board, **args, resolution=resolution, only_nets=frozenset({net}), bounds=window,
+        ).result
+        after = _open(f for f in sub.failed if f[0] == net)
+        new = (sub.wires.get(net, []), sub.vias.get(net, []))
+        if len(after) > len(before) or len(set(new[1])) >= old_vias:
+            continue
+        # the board left out what lies away from the box, so copper reaching
+        # out of it was never checked against that
+        if (new[0] or new[1]) and not _inside(new, window):
+            continue
+        copper[net] = (list(new[0]), list(new[1]))
+        half.pop(net, None)
+        if net in sub.net_half:
+            half[net] = sub.net_half[net]
+        failed = [f for f in failed if f[0] != net] + [f for f in sub.failed if f[0] == net]
+        changed = True
+
+    if not changed:
+        return result
+    out = RouteResult(default_half)
+    for net, (wires, vias) in copper.items():
+        for layer, path in wires:
+            out.add_wire(net, layer, path)
+        for location in dict.fromkeys(vias):
+            out.add_via(net, location)
+    out.failed = failed
+    out.unrouted = len(_open(failed))
+    out.net_half = half
+    out.narrowed = list(result.narrowed)
+    return out
@@ -0,0 +1,248 @@
+"""Window re-route: a last stage for the connections still unrouted.
+
+Around each stuck connection a window is cut: the box of its two end pins
+plus a margin. Every net whose routed copper lies wholly inside it is
+ripped; everything else stays, as fixed copper. The window is then routed
+again on its own, on a finer grid than the whole board can afford, the
+stuck connection's net and the ripped nets only. The result is kept only
+if fewer connections are left unrouted than before; otherwise the board is
+as it was. Each round doubles the margin for the connections still stuck.
+
+It is a last stage, so it is kept cheap: a window's board holds only what
+the window needs (every pin and piece of copper of the nets it reroutes,
+so their connectivity is unchanged, and of the other items only those near
+the window), the smallest windows go first, at most ``max_windows`` run per
+round, and no new window starts once ``budget_s`` seconds are spent.
+
+What makes it differ from re-running the same search near the failure: the
+finer grid finds gaps the board's grid steps over, and the ripped nets go in
+again in a new order around the stuck one. A finer grid on the whole board
+costs routes elsewhere (its cells are slower and its order changes); inside
+a small window it only ever replaces what it can improve.
+"""
+
+from __future__ import annotations
+
+import time
+from typing import Any
+
+from rpmroute.board import BasicBoard, build_board
+from rpmroute.board.items import ObstacleArea, Pin, Trace, Via
+from rpmroute.dsn import DsnBoard
+from rpmroute.geometry import IntBox, IntPoint
+
+from .exact_router import route_board_exact
+from .grid_router import RouteResult
+
+Copper = tuple[list[tuple[int, list[IntPoint]]], list[IntPoint]]
+
+
+def _pin_labels(board) -> dict[tuple[int, str], IntPoint]:
+    """Each pin's location by (net, label), the label a failure names it by."""
+    found: dict[tuple[int, str], IntPoint] = {}
+    for pin in board.get_pins():
+        for net in pin.net_nos:
+            found.setdefault((net, f"{pin.component_ref}-{pin.name}"), pin.location)
+    return found
+
+
+def _end_point(labels, net: int, label: str) -> IntPoint | None:
+    """Where a failure's end is: the first pin its label names."""
+    return labels.get((net, label.split("/")[0]))
+
+
+def _inside(copper: Copper, window: IntBox) -> bool:
+    wires, vias = copper
+    points = [p for _layer, path in wires for p in path] + list(vias)
+    return bool(points) and all(
+        window.ll.x <= p.x <= window.ur.x and window.ll.y <= p.y <= window.ur.y for p in points
+    )
+
+
+def _item_box(item) -> IntBox | None:
+    if isinstance(item, (Pin, Via)):
+        return item.shape.bounding_box() if item.shape is not None else None
+    if isinstance(item, ObstacleArea):
+        return item.bounding_box()
+    if isinstance(item, Trace) and item.corners:
+        h = item.half_width
+        xs, ys = [p.x for p in item.corners], [p.y for p in item.corners]
+        return IntBox(min(xs) - h, min(ys) - h, max(xs) + h, max(ys) + h)
+    return None
+
+
+def _meets(box: IntBox | None, view: IntBox) -> bool:
+    return box is not None and box.ll.x <= view.ur.x and view.ll.x <= box.ur.x and (
+        box.ll.y <= view.ur.y and view.ll.y <= box.ur.y
+    )
+
+
+def _path_box(path: list[IntPoint], grow: int) -> IntBox:
+    xs, ys = [p.x for p in path], [p.y for p in path]
+    return IntBox(min(xs) - grow, min(ys) - grow, max(xs) + grow, max(ys) + grow)
+
+
+def _window_board(
+    base: BasicBoard, base_items: list, view: IntBox, affected: set[int],
+    copper: dict[int, Copper], keep: set[int], half: dict[int, int], default_half: int,
+    via_half: int, via_drill: int, layers: list[int], via_name: str,
+) -> BasicBoard:
+    """The board a window is routed on: the base board's items of the nets
+    being rerouted and those near ``view``, plus the routed copper being kept
+    (all of an affected net's, so its connectivity is the whole board's, and
+    of other nets only what is near ``view``), as fixed copper."""
+    board = BasicBoard(base.layer_structure, base.nets, base.clearance_matrix, base.bounding_box)
+    board.outline = base.outline
+    for item, box in base_items:
+        if (item.net_nos and item.net_nos[0] in affected) or _meets(box, view):
+            board.insert(item)
+    for net in keep:
+        wires, vias = copper.get(net, ([], []))
+        width = half.get(net, default_half)
+        mine = net in affected
+        for layer, path in wires:
+            if len(path) >= 2 and (mine or _meets(_path_box(path, width), view)):
+                board.insert(Trace(net_nos=[net], fixed=True, layer=layer, half_width=width, corners=list(path)))
+        for location in dict.fromkeys(vias):
+            shape = IntBox(location.x - via_half, location.y - via_half,
+                           location.x + via_half, location.y + via_half)
+            if mine or _meets(shape, view):
+                board.insert(Via(
+                    net_nos=[net], fixed=True, padstack_name=via_name, drill=via_drill,
+                    location=location, layers=list(layers), shape=shape,
+                ))
+    return board
+
+
+def _open(failed) -> list:
+    """Failures that are real opens, not connections left to a zone fill."""
+    return [f for f in failed if not (len(f) > 3 and f[3])]
+
+
+def window_reroute(
+    dsn: DsnBoard,
+    result: RouteResult,
+    route_args: dict[str, Any],
+    *,
+    rounds: int,
+    resolution: int,
+    margin: int,
+    via_half: int,
+    via_drill: int,
+    via_name: str,
+    budget_s: float | None = None,
+    max_windows: int = 40,
+) -> RouteResult:
+    """Re-route a window around each still-failing connection; keep only gains.
+
+    ``route_args`` are the exact engine's settings for the whole board (width,
+    clearance, layers, shove, ...); the window runs them at ``resolution``.
+    ``margin`` is the first round's window margin in board units. No new
+    window starts once ``budget_s`` seconds have gone by (None: no limit),
+    and at most ``max_windows`` run per round."""
+    started = time.monotonic()
+    if rounds < 1 or not _open(result.failed):
+        return result
+    default_half = result.half_width
+    copper: dict[int, Copper] = {
+        net: (list(result.wires.get(net, [])), list(result.vias.get(net, [])))
+        for net in set(result.wires) | set(result.vias)
+    }
+    half = dict(result.net_half)
+    failed = list(result.failed)
+    base = build_board(dsn)
+    base_items = [(item, _item_box(item)) for item in base.get_items()]
+    layers = route_args.get("layers") or [
+        i for i, layer in enumerate(base.layer_structure.arr) if layer.is_signal
+    ]
+    labels = _pin_labels(base)
+    # the copper a window's routing can feel from outside it
+    context = 2 * (route_args["trace_width"] + route_args["clearance"]) + 2 * via_half + (
+        route_args.get("edge_clearance") or 0
+    )
+
+    def window_of(entry, reach: int) -> IntBox | None:
+        ends = [_end_point(labels, entry[0], label) for label in entry[1:3]]
+        ends = [p for p in ends if p is not None]
+        if not ends:
+            return None
+        return IntBox(
+            min(p.x for p in ends) - reach, min(p.y for p in ends) - reach,
+            max(p.x for p in ends) + reach, max(p.y for p in ends) + reach,
+        )
+
+    def area(box: IntBox | None) -> float:
+        return float("inf") if box is None else (box.ur.x - box.ll.x) * (box.ur.y - box.ll.y)
+
+    changed = out_of_time = False
+    for rnd in range(rounds):
+        reach = margin * (2 ** rnd)
+
+        # the cheap wins first: the smallest windows
+        todo = sorted(_open(list(failed)), key=lambda f: area(window_of(f, reach)))
+        for entry in todo[:max(int(max_windows), 1)]:
+            if budget_s is not None and time.monotonic() - started >= budget_s:
+                out_of_time = True
+                break
+            if entry not in failed:
+                continue  # an earlier window routed it
+            net = entry[0]
+            window = window_of(entry, reach)
+            if window is None:
+                continue
+            victims = {n for n, c in copper.items() if _inside(c, window)}
+            affected = victims | {net}
+            before = _open(f for f in failed if f[0] in affected)
+            keep = set(copper) - victims
+            view = IntBox(window.ll.x - context, window.ll.y - context,
+                          window.ur.x + context, window.ur.y + context)
+            board = _window_board(base, base_items, view, affected, copper, keep, half,
+                                  default_half, via_half, via_drill, layers, via_name)
+            sub = route_board_exact(
+                board, **route_args, resolution=resolution,
+                only_nets=frozenset(affected), bounds=window,
+                route_first=frozenset((f[0], f[1], f[2]) for f in before),
+            ).result
+            after = _open(f for f in sub.failed if f[0] in affected)
+            if len(after) >= len(before):
+                continue
+            # the window board left out what lies away from it, so copper
+            # reaching out of the window was never checked against it
+            if any(not _inside((sub.wires.get(n, []), sub.vias.get(n, [])), window)
+                   for n in affected if sub.wires.get(n) or sub.vias.get(n)):
+                continue
+            # a net keeping some of its copper is written at one width: the
+            # window's new copper has to have gone in at that width too
+            if any(
+                n not in victims and copper.get(n) and (sub.wires.get(n) or sub.vias.get(n))
+                and sub.net_half.get(n, default_half) != half.get(n, default_half)
+                for n in affected
+            ):
+                continue
+            for n in affected:
+                kept_wires, kept_vias = copper.get(n, ([], [])) if n not in victims else ([], [])
+                copper[n] = (kept_wires + sub.wires.get(n, []), kept_vias + sub.vias.get(n, []))
+                if n in victims:
+                    half.pop(n, None)
+                    if n in sub.net_half:
+                        half[n] = sub.net_half[n]
+            failed = [f for f in failed if f[0] not in affected] + [
+                f for f in sub.failed if f[0] in affected
+            ]
+            changed = True
+        if out_of_time or not _open(failed):
+            break
+
+    if not changed:
+        return result
+    out = RouteResult(default_half)
+    for net, (wires, vias) in copper.items():
+        for layer, path in wires:
+            out.add_wire(net, layer, path)
+        for location in dict.fromkeys(vias):
+            out.add_via(net, location)
+    out.failed = failed
+    out.unrouted = len(_open(failed))
+    out.net_half = half
+    out.narrowed = list(result.narrowed)
+    return out
@@ -1,9 +1,9 @@
-"""Specctra SES (session) writing for freeroute.
+"""Specctra SES (session) writing for rpmroute.

 Public API::

-    from freeroute.dsn import parse_dsn
-    from freeroute.ses import write_ses, RoutingResult, RoutedWire, RoutedVia
+    from rpmroute.dsn import parse_dsn
+    from rpmroute.ses import write_ses, RoutingResult, RoutedWire, RoutedVia

    board = parse_dsn(dsn_text)
    ses_text = write_ses(board)                 # valid no-op session
@@ -1,8 +1,8 @@
 """Specctra SES session-file writer.

 Ports the write path of FreeRouting's ``io/specctra/SesWriter.java`` to operate
-on this project's parsed :class:`~freeroute.dsn.model.DsnBoard` plus an
-in-memory :class:`~freeroute.ses.model.RoutingResult`. The emitted structure is::
+on this project's parsed :class:`~rpmroute.dsn.model.DsnBoard` plus an
+in-memory :class:`~rpmroute.ses.model.RoutingResult`. The emitted structure is::

    (session <name>
      (base_design <name>)
@@ -30,8 +30,8 @@ from __future__ import annotations

 import math

-from freeroute.dsn.model import DsnBoard
-from freeroute.dsn.shapes import Circle, Path, Polygon, Rectangle, Shape
+from rpmroute.dsn.model import DsnBoard
+from rpmroute.dsn.shapes import Circle, Path, Polygon, Rectangle, Shape

 from .indent import Identifier, IndentWriter
 from .model import RoutedNet, RoutedVia, RoutedWire, RoutingResult
@@ -2,7 +2,7 @@

 from __future__ import annotations

-from freeroute.board import (
+from rpmroute.board import (
    ClearanceMatrix,
    CoordinateTransform,
    Layer,
@@ -15,9 +15,9 @@ import sys

 import pytest

-from freeroute.board import BasicBoard, ObstacleArea, Pin, build_board
-from freeroute.dsn import parse_dsn
-from freeroute.geometry import IntPoint
+from rpmroute.board import BasicBoard, ObstacleArea, Pin, build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.geometry import IntPoint

 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))

@@ -184,7 +184,7 @@ def test_place_keepout_does_not_block_routing():


 def test_grid_router_leaves_the_interior_of_a_ring_keepout_open():
-    from freeroute.route.pipeline import route_dsn_board
+    from rpmroute.route.pipeline import route_dsn_board

    ring_only = "\n".join(
        line for line in _RING_DSN.splitlines() if "wire_keepout" not in line
@@ -251,7 +251,7 @@ def test_oval_pad_keeps_its_width():


 def test_via_size_comes_from_the_via_padstack():
-    from freeroute.route.pipeline import _via_half_board
+    from rpmroute.route.pipeline import _via_half_board

    assert _via_half_board(parse_dsn(_PAD_DSN), 10) == 3000   # 0.6 mm via, board units

@@ -279,7 +279,7 @@ def test_a_keepout_named_rule_area_takes_no_clearance():


 def _route_channel(name):
-    from freeroute.route.pipeline import build_exact_routing_result
+    from rpmroute.route.pipeline import build_exact_routing_result

    return build_exact_routing_result(parse_dsn(_CHANNEL_DSN.format(name=name)), resolution=2)

@@ -2,8 +2,8 @@

 from __future__ import annotations

-from freeroute.board import ShapeSearchTree, TreeShape
-from freeroute.geometry import IntBox
+from rpmroute.board import ShapeSearchTree, TreeShape
+from rpmroute.geometry import IntBox


 def shape(owner, net, layer, box, routed=False):
@@ -6,10 +6,10 @@ from pathlib import Path

 import pytest

-from freeroute.dsn import parse_dsn
-from freeroute.dsn.reader import DsnParseError
-from freeroute.dsn.shapes import Circle, Rectangle
-from freeroute.dsn.shapes import Path as DsnPath
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.reader import DsnParseError
+from rpmroute.dsn.shapes import Circle, Rectangle
+from rpmroute.dsn.shapes import Path as DsnPath

 FIXTURES = Path(__file__).parent / "fixtures"

@@ -4,8 +4,8 @@ from __future__ import annotations

 import pytest

-from freeroute.dsn.sexp import SExp, parse
-from freeroute.dsn.tokenizer import DsnSyntaxError, Token
+from rpmroute.dsn.sexp import SExp, parse
+from rpmroute.dsn.tokenizer import DsnSyntaxError, Token


 def test_parse_simple_head_and_values():
@@ -2,8 +2,8 @@

 from __future__ import annotations

-from freeroute.dsn.sexp import parse
-from freeroute.dsn.shapes import (
+from rpmroute.dsn.sexp import parse
+from rpmroute.dsn.shapes import (
    Circle,
    Path,
    Polygon,
@@ -4,7 +4,7 @@ from __future__ import annotations

 import pytest

-from freeroute.dsn.tokenizer import DsnSyntaxError, TokenKind, tokenize
+from rpmroute.dsn.tokenizer import DsnSyntaxError, TokenKind, tokenize


 def kinds(text: str) -> list[TokenKind]:
@@ -6,7 +6,7 @@ containment and degenerate (empty / point / segment) tiles.

 from __future__ import annotations

-from freeroute.geometry import IntBox, IntPoint, IntVector, RationalPoint
+from rpmroute.geometry import IntBox, IntPoint, IntVector, RationalPoint


 def test_measures():
@@ -5,7 +5,7 @@ Oracles hand-derived from ``geometry/planar/{Direction,IntDirection}.java``.

 from __future__ import annotations

-from freeroute.geometry import Direction, IntDirection, IntPoint, IntVector, Side
+from rpmroute.geometry import Direction, IntDirection, IntPoint, IntVector, Side


 def test_normalized_direction_reduces_by_gcd():
@@ -5,7 +5,7 @@ Oracles hand-derived from ``geometry/planar/Line.java``.

 from __future__ import annotations

-from freeroute.geometry import IntPoint, Line, RationalPoint, Side
+from rpmroute.geometry import IntPoint, Line, RationalPoint, Side


 def test_side_of_point():
@@ -79,7 +79,7 @@ def test_intersection_approx_matches_exact():
 def test_translate_and_opposite():
    line = Line.from_coords(0, 0, 4, 0)
    assert line.opposite().direction().equals(line.direction()) is False
-    from freeroute.geometry import IntVector
+    from rpmroute.geometry import IntVector

    moved = line.translate_by(IntVector(0, 5))
    assert moved.side_of(IntPoint(2, 5)) == Side.COLLINEAR
@@ -7,7 +7,7 @@ import random

 import pytest

-from freeroute.geometry import IntBox, IntPoint, ceil_sqrt2, overlaps_2d, segment_octagon
+from rpmroute.geometry import IntBox, IntPoint, ceil_sqrt2, overlaps_2d, segment_octagon


@pytest.mark.parametrize("r", [0, 1, 2, 3, 1000, 2000, 3000, 12345, 999999])
@@ -8,7 +8,7 @@ Java ``long``, and rational equality.

 from __future__ import annotations

-from freeroute.geometry import (
+from rpmroute.geometry import (
    IntPoint,
    IntVector,
    RationalPoint,
@@ -139,7 +139,7 @@ def test_rational_point_infinite():


 def test_rational_point_contained_in_box_exact():
-    from freeroute.geometry import IntBox
+    from rpmroute.geometry import IntBox

    box = IntBox(0, 0, 2, 2)
    assert RationalPoint(3, 2, 2).is_contained_in(box)  # (1.5, 1.0) inside
@@ -13,9 +13,9 @@ from __future__ import annotations

 import pytest

-from freeroute.geometry import IntPoint, Side
-from freeroute.geometry.polygon import Polygon
-from freeroute.geometry.polygon_shape import PolygonShape
+from rpmroute.geometry import IntPoint, Side
+from rpmroute.geometry.polygon import Polygon
+from rpmroute.geometry.polygon_shape import PolygonShape


 def pts(*coords):
@@ -2,7 +2,7 @@

 from __future__ import annotations

-from freeroute.geometry import (
+from rpmroute.geometry import (
    IntBox,
    IntPoint,
    Polyline,
@@ -16,7 +16,7 @@ Source: ``geometry/planar/{TileShape,Simplex}.java``.

 from __future__ import annotations

-from freeroute.geometry import IntBox, IntPoint, Line, Side, Simplex
+from rpmroute.geometry import IntBox, IntPoint, Line, Side, Simplex


 def _grid(lo: int, hi: int):
@@ -162,7 +162,7 @@ def test_get_instance_detects_empty_from_opposing_halfplanes():

 def test_translate_preserves_shape():
    tri = right_triangle()
-    from freeroute.geometry import IntVector
+    from rpmroute.geometry import IntVector

    moved = tri.translate_by(IntVector(100, 50))
    for p in _grid(-3, 13):
@@ -1,8 +1,8 @@
 """FreeRouting JAR oracle for behaviour-level validation.

-**Dev/test only — not part of the shipped package** (freeroute is Java-free by
+**Dev/test only — not part of the shipped package** (rpmroute is Java-free by
 design). This runs the reference FreeRouting JAR to route a Specctra DSN so that
-freeroute's own output can be diffed against the reference implementation. There
+rpmroute's own output can be diffed against the reference implementation. There
 are no unit-test oracles for FreeRouting's geometry/router, so the oracle is how
 we validate at the behaviour level: same DSN in, compare routed connectivity.

@@ -10,7 +10,7 @@ Tests that use this skip automatically when a Java 21+ runtime or the JAR is not
 available (e.g. CI without a JVM), so the normal suite stays Java-free.

 Overrides:
- ``FREEROUTE_ORACLE_JAVA`` — explicit path to a ``java`` binary.
+- ``RPMROUTE_ORACLE_JAVA`` (or the older ``FREEROUTE_ORACLE_JAVA``) — explicit path to a ``java`` binary.
 - ``FREEROUTING_JAR`` — explicit path to a freerouting JAR.
 """

@@ -27,7 +27,7 @@ import tempfile

 import pytest

-from freeroute.dsn.sexp import parse
+from rpmroute.dsn.sexp import parse

 _MIN_JAVA_MAJOR = 21
 _REPO_ROOT = Path(__file__).resolve().parents[1]
@@ -60,7 +60,7 @@ def _java_major(java: str) -> int:
 def find_java() -> str | None:
    """Return a path to a Java >= 21 runtime, or None."""
    candidates: list[str] = []
-    override = os.environ.get("FREEROUTE_ORACLE_JAVA")
+    override = os.environ.get("RPMROUTE_ORACLE_JAVA") or os.environ.get("FREEROUTE_ORACLE_JAVA")
    if override:
        candidates.append(override)
    java_home = os.environ.get("JAVA_HOME")
@@ -14,11 +14,11 @@ import math

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.geometry import IntPoint, overlaps_2d, segment_slab
-from freeroute.route.grid_router import GridRouter
-from freeroute.route.pipeline import (
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.geometry import IntPoint, overlaps_2d, segment_slab
+from rpmroute.route.grid_router import GridRouter
+from rpmroute.route.pipeline import (
    _rule_clearance_dsn,
    _rule_width_dsn,
    _via_half_board,
@@ -107,7 +107,7 @@ def test_a_pad_on_the_grid_axes_keeps_the_usual_exits():
 def test_a_slanted_slab_is_tight_where_a_bounding_box_is_not():
    slab = segment_slab(IntPoint(0, 0), IntPoint(10000, 10000), 750)
    # a point beside the diagonal but inside its bounding box
-    from freeroute.geometry import IntBox
+    from rpmroute.geometry import IntBox

    assert not overlaps_2d(slab, IntBox(8000, 0, 8100, 100))
    assert overlaps_2d(slab, IntBox(4900, 4900, 5100, 5100))
@@ -16,11 +16,11 @@ from pathlib import Path

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import parse
-from freeroute.geometry import IntBox, IntPoint, overlaps_2d, segment_octagon
-from freeroute.route import route, route_dsn_board_exact
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import parse
+from rpmroute.geometry import IntBox, IntPoint, overlaps_2d, segment_octagon
+from rpmroute.route import route, route_dsn_board_exact

 FIXTURES = Path(__file__).resolve().parent.parent / "dsn" / "fixtures"
 DIAGONAL_WIN = FIXTURES / "diagonal_win.dsn"
@@ -55,7 +55,7 @@ def _pins_by_net(fixture):


 def _rule_clearance_board(fixture):
-    from freeroute.route.pipeline import _rule_clearance_dsn
+    from rpmroute.route.pipeline import _rule_clearance_dsn

    dsn = parse_dsn(fixture.read_text())
    return round(_rule_clearance_dsn(dsn) * max(dsn.resolution.value, 1))
@@ -15,12 +15,12 @@ import sys

 import pytest

-from freeroute.board import ShapeSearchTree, TreeShape, build_board
-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import parse
-from freeroute.geometry import IntBox, Polyline, PolylineShape
-from freeroute.route import route, route_dsn_board, route_dsn_board_exact
-from freeroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn
+from rpmroute.board import ShapeSearchTree, TreeShape, build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import parse
+from rpmroute.geometry import IntBox, Polyline, PolylineShape
+from rpmroute.route import route, route_dsn_board, route_dsn_board_exact
+from rpmroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn

 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))

@@ -2,9 +2,9 @@

 from __future__ import annotations

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.route.pipeline import route_dsn_board_exact
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.pipeline import route_dsn_board_exact

 _DSN = """(pcb wired (parser) (resolution um 10) (unit um)
  (structure
@@ -95,9 +95,9 @@ def test_a_fanned_out_signal_is_routed_from_its_via():

 def test_the_session_never_repeats_copper_already_on_the_board():
    # the JAR writes the DSN's wiring back into its session, and an applier
-    # then adds it a second time on top of itself; freeroute writes only
+    # then adds it a second time on top of itself; rpmroute writes only
    # what it routed
-    from freeroute.route.pipeline import build_exact_routing_result
+    from rpmroute.route.pipeline import build_exact_routing_result

    fixed_vias = {(5000.0, -11500.0), (10000.0, -11500.0)}
    fixed_paths = {(5000.0, -10000.0, 5000.0, -11500.0), (10000.0, -10000.0, 10000.0, -11500.0),
@@ -12,11 +12,11 @@ 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 (
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.geometry import IntBox, Simplex
+from rpmroute.route.grid_router import GridRouter
+from rpmroute.route.pipeline import (
    _rule_clearance_dsn,
    _rule_width_dsn,
    _via_half_board,
@@ -268,9 +268,9 @@ def test_a_via_by_a_chamfered_corner_is_judged_round():
    """The grid keeps a via's centre its radius plus the edge clearance from
    the outline. The exact check used the via's square, whose corner reaches
    past a 45-degree chamfer where the round via does not."""
-    from freeroute.board.outline import BoardOutline
-    from freeroute.geometry import IntBox, IntPoint
-    from freeroute.route.exact_router import _inside_outline
+    from rpmroute.board.outline import BoardOutline
+    from rpmroute.geometry import IntBox, IntPoint
+    from rpmroute.route.exact_router import _inside_outline

    # a 10 mm square with its lower-left corner cut at 45 degrees
    outline = BoardOutline([IntPoint(*p) for p in
@@ -6,10 +6,10 @@ from pathlib import Path

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.route.grid_router import GridRouter
-from freeroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn, route_dsn_board
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.grid_router import GridRouter
+from rpmroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn, route_dsn_board

 FIXTURES = Path(__file__).resolve().parent.parent / "dsn" / "fixtures"

@@ -2,8 +2,8 @@

 from __future__ import annotations

-from freeroute.dsn import parse_dsn
-from freeroute.route.pipeline import build_exact_routing_result
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.pipeline import build_exact_routing_result

 _BOARD = """(pcb widths (parser) (resolution um 10) (unit um)
  (structure
@@ -4,8 +4,8 @@ from __future__ import annotations

 from pathlib import Path

-from freeroute.cli import main
-from freeroute.route.orders import (
+from rpmroute.cli import main
+from rpmroute.route.orders import (
    best_of_orders,
    candidate_seeds,
    promote_failures,
@@ -6,9 +6,9 @@ import math

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.route.pipeline import route_dsn_board_exact
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.pipeline import route_dsn_board_exact

 # 20 x 20 mm board whose corners are rounded with a 3 mm radius, as polylines
 _R = 3000.0
@@ -70,7 +70,7 @@ def test_every_pin_of_a_half_millimetre_pitch_row_escapes(resolution):


 def test_resolution_one_has_no_halo_so_the_grid_is_unchanged():
-    from freeroute.route.grid_router import GridRouter
+    from rpmroute.route.grid_router import GridRouter

    board = build_board(parse_dsn(_dsn("", "")))
    assert GridRouter(board, trace_width=2500, clearance=1500)._halo_offsets == []
@@ -101,7 +101,7 @@ def test_heuristic_weight_bounds_route_length():

 # --- copper zones (DSN planes) -----------------------------------------------
 # rc4 power stage: pads inside "keep router off" pours connect through the pour,
-# and freeroute, not knowing zones, dropped every such connection.
+# and rpmroute, not knowing zones, dropped every such connection.

 _ZONE = "(plane N (polygon F.Cu 0  4000 -4000  10000 -4000  10000 -10000  4000 -10000  4000 -4000))"
 _NO_TRACKS = "(wire_keepout \"pour\" (polygon F.Cu 0  4000 -4000  10000 -4000  10000 -10000  4000 -10000))"
@@ -121,7 +121,7 @@ def test_planes_are_read_and_are_not_obstacles():


 def test_pads_in_one_zone_need_no_route_between_them():
-    from freeroute.route.grid_router import _connected_groups
+    from rpmroute.route.grid_router import _connected_groups

    board = build_board(_zone_board())
    pins = sorted(board.get_pins(), key=lambda p: p.component_ref)
@@ -155,7 +155,7 @@ def test_a_pour_other_nets_can_cross_is_not_trusted_to_connect():

 def test_cli_names_the_connections_it_could_not_route(tmp_path, capsys):
    # a keepout wall across the board on both layers: A and B cannot be joined
-    from freeroute.cli import main
+    from rpmroute.cli import main

    wall = " ".join(
        f"(keepout \"wall\" (polygon {layer} 0  9000 1000  11000 1000  11000 -21000  9000 -21000))"
@@ -218,7 +218,7 @@ def test_a_pad_outside_the_plane_routes_to_it():


 def test_a_through_hole_pad_inside_a_plane_needs_no_route():
-    from freeroute.route.grid_router import _connected_groups
+    from rpmroute.route.grid_router import _connected_groups

    board = build_board(parse_dsn(_four_layer_dsn()))
    plane = [z for z in board.get_conduction_areas() if z.name == "GND"]
@@ -0,0 +1,123 @@
+"""Via reduction: each net with vias is routed again with vias made dear,
+kept only when it fails nothing new and has fewer vias."""
+
+from __future__ import annotations
+
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.geometry import IntPoint
+from rpmroute.route.grid_router import RouteResult
+from rpmroute.route.pipeline import (
+    _rule_clearance_dsn,
+    _rule_width_dsn,
+    _via_half_board,
+    route_dsn_board_exact,
+)
+from rpmroute.route.vias import reduce_vias
+
+VIA = "Via[0-1]_600:300_um"
+
+
+def _board(second_on_bottom: bool = False) -> str:
+    """Two pads 14 mm apart on an empty two-layer board; the second on the
+    bottom layer when ``second_on_bottom``."""
+    p2_stack = "Bot_Pad" if second_on_bottom else "Top_Pad"
+    return f"""(pcb "vias.dsn"
+  (parser (string_quote ") (space_in_quoted_tokens on) (host_cad "t") (host_version "1"))
+  (resolution um 10)
+  (unit um)
+  (structure
+    (layer F.Cu (type signal) (property (index 0)))
+    (layer B.Cu (type signal) (property (index 1)))
+    (boundary (path pcb 0  0 0  20000 0  20000 -10000  0 -10000  0 0))
+    (via "{VIA}")
+    (rule (width 200) (clearance 200))
+  )
+  (library
+    (padstack Top_Pad (shape (rect F.Cu -300 -300 300 300)) (attach off))
+    (padstack Bot_Pad (shape (rect B.Cu -300 -300 300 300)) (attach off))
+    (padstack "{VIA}" (shape (circle F.Cu 600)) (shape (circle B.Cu 600)) (attach off))
+    (image TOP (pin Top_Pad 1 0 0))
+    (image SECOND (pin {p2_stack} 1 0 0))
+  )
+  (placement
+    (component TOP (place P1 3000 -5000 front 0))
+    (component SECOND (place P2 17000 -5000 front 0))
+  )
+  (network
+    (net N (pins P1-1 P2-1))
+    (class default (rule (width 200) (clearance 200)))
+  )
+  (wiring)
+)
+"""
+
+
+def _route_args(dsn) -> dict:
+    scale = max(dsn.resolution.value, 1)
+    return {
+        "heuristic_weight": 1.0,
+        "via_half": _via_half_board(dsn, scale),
+        "edge_clearance": None,
+        "trace_width": round(_rule_width_dsn(dsn) * scale),
+        "clearance": round(_rule_clearance_dsn(dsn) * scale),
+        "layers": None,
+        "max_passes": 10,
+        "rip_up": True,
+        "shove": False,
+        "diagonal": False,
+        "rollback": True,
+        "tree_nets": True,
+        "net_widths": {},
+        "via_drill": None,
+        "hole_to_hole": 0,
+        "via_cost": 10.0,
+    }
+
+
+def _reduce(text: str, result: RouteResult) -> RouteResult:
+    dsn = parse_dsn(text)
+    args = _route_args(dsn)
+    return reduce_vias(
+        dsn, result, args, resolution=1, margin=20000,
+        via_half=args["via_half"], via_drill=2 * args["via_half"], via_name=VIA,
+    )
+
+
+def _pins(text: str) -> tuple[IntPoint, IntPoint]:
+    pins = {p.component_ref: p.location for p in build_board(parse_dsn(text)).get_pins()}
+    return pins["P1"], pins["P2"]
+
+
+def test_a_needless_via_pair_is_routed_out():
+    text = _board()
+    a, b = _pins(text)
+    # a detour: down to the bottom layer and back up, for no reason
+    v1, v2 = IntPoint(a.x + 40000, a.y), IntPoint(b.x - 40000, b.y)
+    detour = RouteResult(1000)
+    detour.add_wire(1, 0, [a, v1])
+    detour.add_via(1, v1)
+    detour.add_wire(1, 1, [v1, v2])
+    detour.add_via(1, v2)
+    detour.add_wire(1, 0, [v2, b])
+    out = _reduce(text, detour)
+    assert out.failed == []
+    assert sum(len(v) for v in out.vias.values()) == 0
+    assert out.wires.get(1)
+
+
+def test_a_needed_via_stays():
+    text = _board(second_on_bottom=True)
+    exact, _scale, _layers = route_dsn_board_exact(parse_dsn(text), resolution=1)
+    routed = exact.result
+    assert routed.failed == []
+    vias_before = sum(len(set(v)) for v in routed.vias.values())
+    assert vias_before >= 1
+    out = _reduce(text, routed)
+    assert out.failed == []
+    assert sum(len(set(v)) for v in out.vias.values()) == vias_before
+
+
+def test_the_flag_runs_the_stage_end_to_end():
+    exact, _scale, _layers = route_dsn_board_exact(parse_dsn(_board()), resolution=1, reduce_vias=True)
+    assert exact.result.failed == []
@@ -6,10 +6,10 @@ from pathlib import Path

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.route.grid_router import GridRouter
-from freeroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn, route_dsn_board
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.grid_router import GridRouter
+from rpmroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn, route_dsn_board

 FIXTURES = Path(__file__).resolve().parent.parent / "dsn" / "fixtures"

@@ -23,11 +23,11 @@ from pathlib import Path

 import pytest

-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import parse
-from freeroute.geometry import Polyline, PolylineShape
-from freeroute.route import route, route_dsn_board_rooms
-from freeroute.route.pipeline import _rule_clearance_dsn
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import parse
+from rpmroute.geometry import Polyline, PolylineShape
+from rpmroute.route import route, route_dsn_board_rooms
+from rpmroute.route.pipeline import _rule_clearance_dsn

 FIXTURES = Path(__file__).resolve().parent.parent / "dsn" / "fixtures"
 CHANNEL_PACK = FIXTURES / "channel_pack.dsn"
@@ -134,7 +134,7 @@ def test_channel_pack_is_deterministic():
 def test_channel_pack_endpoints_stay_on_pads():
    dsn = parse_dsn(CHANNEL_PACK.read_text())
    board_pins: dict[int, set[tuple[int, int]]] = {}
-    from freeroute.board import build_board
+    from rpmroute.board import build_board

    for pin in build_board(dsn).get_pins():
        for net_no in pin.net_nos:
@@ -13,11 +13,11 @@ import sys

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import parse
-from freeroute.geometry import Polyline
-from freeroute.route import route, route_dsn_board_exact, route_dsn_board_rooms
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import parse
+from rpmroute.geometry import Polyline
+from rpmroute.route import route, route_dsn_board_exact, route_dsn_board_rooms

 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))

@@ -31,7 +31,7 @@ WIDE_DOOR = FIXTURES / "rooms_wide_door.dsn"


 def _clearance(dsn, scale):
-    from freeroute.route.pipeline import _rule_clearance_dsn
+    from rpmroute.route.pipeline import _rule_clearance_dsn

    return round(_rule_clearance_dsn(dsn) * scale)

@@ -32,12 +32,12 @@ import sys

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import parse
-from freeroute.geometry import IntBox, IntPoint, Polyline, PolylineShape
-from freeroute.route import route, route_dsn_board_exact, route_dsn_board_rooms
-from freeroute.route.pipeline import _rule_clearance_dsn
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import parse
+from rpmroute.geometry import IntBox, IntPoint, Polyline, PolylineShape
+from rpmroute.route import route, route_dsn_board_exact, route_dsn_board_rooms
+from rpmroute.route.pipeline import _rule_clearance_dsn


 def _emitted_drc_violations(result, clearance):
@@ -265,8 +265,8 @@ def test_shove_is_byte_identical_on_foundation_fixtures(fixture):


 def test_project_gate_reduces_to_clamp_without_occupancy():
-    from freeroute.board.search_tree import ShapeSearchTree
-    from freeroute.route.room_router import _Door, _edge_gate, _project_gate
+    from rpmroute.board.search_tree import ShapeSearchTree
+    from rpmroute.route.room_router import _Door, _edge_gate, _project_gate

    door = _Door(other=1, kind="edge", lo=IntPoint(0, 100), hi=IntPoint(200, 100))
    tree = ShapeSearchTree()
@@ -277,8 +277,8 @@ def test_project_gate_reduces_to_clamp_without_occupancy():


 def test_project_gate_avoids_other_net_copper_on_the_door():
-    from freeroute.board.search_tree import ShapeSearchTree, TreeShape
-    from freeroute.route.room_router import _Door, _project_gate
+    from rpmroute.board.search_tree import ShapeSearchTree, TreeShape
+    from rpmroute.route.room_router import _Door, _project_gate

    door = _Door(other=1, kind="edge", lo=IntPoint(0, 100), hi=IntPoint(200, 100))
    tree = ShapeSearchTree()
@@ -293,7 +293,7 @@ def test_project_gate_avoids_other_net_copper_on_the_door():


 def test_free_intervals_splits_around_forbidden_band():
-    from freeroute.route.room_router import _best_free_point, _free_intervals
+    from rpmroute.route.room_router import _best_free_point, _free_intervals

    free = _free_intervals(0, 200, [(87, 113)])
    assert free == [(0, 87), (113, 200)]
@@ -16,11 +16,11 @@ import sys

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import parse
-from freeroute.route import route, route_dsn_board
-from freeroute.ses.writer import ses_scale
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import parse
+from rpmroute.route import route, route_dsn_board
+from rpmroute.ses.writer import ses_scale

 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))

@@ -287,11 +287,11 @@ def test_connectivity_parity_on_congested_board():
    if not HAS_ORACLE:
        pytest.skip("FreeRouting oracle unavailable")
    our_nets = routed_net_set(route(RIPUP.read_text()))
-    assert our_nets == {"NET_A", "NET_B"}  # freeroute connects both via rip-up
+    assert our_nets == {"NET_A", "NET_B"}  # rpmroute connects both via rip-up
    oracle_nets = routed_net_set(route_dsn(RIPUP, max_passes=3, timeout=300))
    if not oracle_nets:
        # the reference JAR does not route this synthetic single-signal-layer
-        # board (it expects a routing/via layer); freeroute's rip-up connecting
+        # board (it expects a routing/via layer); rpmroute's rip-up connecting
        # both nets is already asserted above and by the fast tests.
        pytest.skip("reference JAR routed nothing on the synthetic single-layer board")
    assert oracle_nets <= our_nets  # rip-up matches the JAR's connectivity
@@ -306,7 +306,7 @@ def test_connectivity_parity_on_crossing_board():
    our_nets = routed_net_set(route(CROSSING.read_text()))
    oracle_nets = routed_net_set(route_dsn(CROSSING, max_passes=3, timeout=300))
    assert oracle_nets, "oracle routed nothing on a routable board"
-    assert oracle_nets <= our_nets  # freeroute connects every net the JAR does
+    assert oracle_nets <= our_nets  # rpmroute connects every net the JAR does


@pytest.mark.oracle
@@ -17,10 +17,10 @@ import sys

 import pytest

-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import parse
-from freeroute.route import route, route_dsn_board_exact
-from freeroute.route.pipeline import _rule_clearance_dsn
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import parse
+from rpmroute.route import route, route_dsn_board_exact
+from rpmroute.route.pipeline import _rule_clearance_dsn

 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))

@@ -66,7 +66,7 @@ def test_shove_result_is_deterministic():


 def test_shoved_trace_endpoints_still_on_pads():
-    from freeroute.board import build_board
+    from rpmroute.board import build_board

    on, _, _ = route_dsn_board_exact(parse_dsn(SHOVE.read_text()), rip_up=False, shove=True)
    board = build_board(parse_dsn(SHOVE.read_text()))
@@ -0,0 +1,162 @@
+"""Smoothing: staircases become octilinear runs, corners are chamfered, and
+nothing it keeps (ends, vias, joints, pads it crosses) moves."""
+
+from __future__ import annotations
+
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.smooth import smooth
+from rpmroute.route.verify import verify_result
+from rpmroute.ses.model import RoutedVia, RoutedWire, RoutingResult
+
+VIA = "Via[0-1]_600:300_um"
+
+
+def _board(extra_pads: str = "", extra_places: str = "", nets: str = "") -> str:
+    """A 30 x 30 mm two-layer board, units um, 0.2 mm track and clearance.
+    A1 at (2, -2) mm and A2 at (22, -22) mm are net SIG."""
+    return f"""(pcb "smooth.dsn"
+  (parser (string_quote ") (space_in_quoted_tokens on) (host_cad "t") (host_version "1"))
+  (resolution um 10)
+  (unit um)
+  (structure
+    (layer F.Cu (type signal) (property (index 0)))
+    (layer B.Cu (type signal) (property (index 1)))
+    (boundary (path pcb 0  0 0  30000 0  30000 -30000  0 -30000  0 0))
+    (via "{VIA}")
+    (rule (width 200) (clearance 200))
+  )
+  (library
+    (padstack P (shape (rect F.Cu -300 -300 300 300)) (attach off))
+    (padstack "{VIA}" (shape (circle F.Cu 600)) (shape (circle B.Cu 600)) (attach off))
+    (image PAD (pin P 1 0 0))
+    {extra_pads}
+  )
+  (placement
+    (component PAD (place A1 2000 -2000 front 0) (place A2 22000 -22000 front 0) {extra_places})
+  )
+  (network
+    (net SIG (pins A1-1 A2-1))
+    {nets}
+    (class default (rule (width 200) (clearance 200)))
+  )
+  (wiring)
+)
+"""
+
+
+def _staircase(a, b, step):
+    """Points from ``a`` to ``b`` (DSN um) in alternating x and y steps."""
+    (x, y), (bx, by) = a, b
+    pts = [(x, y)]
+    sx = step if bx > x else -step
+    sy = step if by > y else -step
+    while (x, y) != (bx, by):
+        if x != bx:
+            x = x + sx if abs(bx - x) > step else bx
+            pts.append((x, y))
+        if y != by:
+            y = y + sy if abs(by - y) > step else by
+            pts.append((x, y))
+    return pts
+
+
+def _wire(pts, layer="F.Cu", fixed=False):
+    return RoutedWire(layer=layer, width=200, coords=[v for p in pts for v in p], fixed=fixed)
+
+
+def _points(wire):
+    c = wire.coords
+    return [(round(c[i]), round(c[i + 1])) for i in range(0, len(c), 2)]
+
+
+def _result(*wires, vias=(), net="SIG"):
+    result = RoutingResult()
+    for w in wires:
+        result.add_wire(net, w)
+    for x, y in vias:
+        result.net(net, create=True).vias.append(RoutedVia(padstack=VIA, x=x, y=y))
+    return result
+
+
+def test_a_staircase_becomes_one_diagonal():
+    dsn = parse_dsn(_board())
+    stair = _staircase((2000, -2000), (22000, -22000), 1000)
+    result = _result(_wire(stair))
+    report = smooth(dsn, result)
+    pts = _points(result.nets[0].wires[0])
+    assert pts == [(2000, -2000), (22000, -22000)]
+    assert report.wires_changed == 1 and report.after.right_angles == 0
+    assert report.after.total_mm < report.before.total_mm
+    assert verify_result(dsn, result).clean
+
+
+def test_a_pad_in_the_way_is_gone_round():
+    # another net's pad sits on the diagonal shortcut of an L-shaped route
+    dsn = parse_dsn(_board(extra_places="(place B1 12000 -12000 front 0) (place B2 28000 -28000 front 0)",
+                           nets="(net OTHER (pins B1-1 B2-1))"))
+    result = _result(_wire([(2000, -2000), (22000, -2000), (22000, -22000)]))
+    report = smooth(dsn, result)
+    pts = _points(result.nets[0].wires[0])
+    assert pts[0] == (2000, -2000) and pts[-1] == (22000, -22000)
+    assert report.wires_changed == 1  # the corner is chamfered, short of the pad
+    assert verify_result(dsn, result).clean
+
+
+def test_a_joint_and_a_via_stay():
+    dsn = parse_dsn(_board(extra_places="(place A3 22000 -2000 front 0)",
+                           nets="").replace("(pins A1-1 A2-1)", "(pins A1-1 A2-1 A3-1)"))
+    stair = _staircase((2000, -2000), (22000, -22000), 1000)
+    joint = stair[11]  # A3's leg ends here, on the staircase
+    leg = _wire([(22000, -2000), (joint[0], -2000), joint])
+    via = stair[25]
+    result = _result(_wire(stair), leg, vias=[via])
+    smooth(dsn, result)
+    pts = _points(result.nets[0].wires[0])
+    assert joint in pts and via in pts
+    assert pts[0] == (2000, -2000) and pts[-1] == (22000, -22000)
+    assert verify_result(dsn, result).clean
+
+
+def test_the_board_edge_is_kept_clear_of():
+    # a staircase hugging the top edge: a chamfer may not push copper over it
+    dsn = parse_dsn(_board(extra_places="(place A3 22000 -500 front 0)").replace(
+        "(pins A1-1 A2-1)", "(pins A1-1 A3-1)"))
+    wire = _wire([(2000, -2000), (2000, -500), (22000, -500)])
+    result = _result(wire)
+    smooth(dsn, result, edge_clearance_mm=0.3)
+    for _x, y in _points(result.nets[0].wires[0]):
+        assert -y >= 300 + 100  # half width + edge clearance from y = 0
+
+
+def test_fixed_wiring_is_left_alone():
+    dsn = parse_dsn(_board())
+    stair = _staircase((2000, -2000), (22000, -22000), 1000)
+    result = _result(_wire(stair, fixed=True))
+    report = smooth(dsn, result)
+    assert _points(result.nets[0].wires[0]) == stair
+    assert report.wires == 0
+
+
+def test_a_detour_with_nothing_in_its_way_is_straightened():
+    dsn = parse_dsn(_board(extra_places="(place A3 22000 -2000 front 0)").replace(
+        "(pins A1-1 A2-1)", "(pins A3-1 A2-1)"))
+    # a U out to x = 12 mm and back, with nothing between its ends
+    result = _result(_wire([(22000, -2000), (12000, -2000), (12000, -22000), (22000, -22000)]))
+    report = smooth(dsn, result)
+    assert _points(result.nets[0].wires[0]) == [(22000, -2000), (22000, -22000)]
+    assert (report.before.right_angles, report.after.right_angles) == (2, 0)
+    assert verify_result(dsn, result).clean
+
+
+def test_a_jog_too_small_for_a_long_diagonal_stays_square():
+    # a 0.1 mm jog halfway: its 45-degree leg would be shorter than two track
+    # widths, a kink beside the copper that leaves pour slivers
+    dsn = parse_dsn(_board(extra_places="(place A3 2100 -22000 front 0)").replace(
+        "(pins A1-1 A2-1)", "(pins A1-1 A3-1)"))
+    wire = [(2000, -2000), (2000, -12000), (2100, -12000), (2100, -22000)]
+    result = _result(_wire(wire))
+    smooth(dsn, result)
+    pts = _points(result.nets[0].wires[0])
+    for a, b in zip(pts, pts[1:], strict=False):
+        if a[0] != b[0] and a[1] != b[1]:
+            assert (b[0] - a[0]) ** 2 + (b[1] - a[1]) ** 2 >= (2 * 200) ** 2
@@ -8,12 +8,12 @@ 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
+from rpmroute.board import build_board
+from rpmroute.board.items import Pin
+from rpmroute.dsn import parse_dsn
+from rpmroute.geometry import IntPoint
+from rpmroute.route.grid_router import GridRouter
+from rpmroute.route.pipeline import route_dsn_board_exact


 def _row(x0: int, pins: int = 6, skew: int = 3000) -> str:
@@ -5,11 +5,11 @@ from __future__ import annotations

 import pytest

-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.route import exact_router
-from freeroute.route.grid_router import GridRouter, RouteResult
-from freeroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.route import exact_router
+from rpmroute.route.grid_router import GridRouter, RouteResult
+from rpmroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn

 # P1 and P2 are nearest each other, so the tree pairs them first; P3 sits
 # under the middle of that leg, 50 mm below it and 90 mm from either pin.
@@ -0,0 +1,42 @@
+"""verify_result: copper no engine checked is checked on exact shapes."""
+
+from pathlib import Path
+
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.verify import verify_result
+from rpmroute.ses.model import RoutedWire, RoutingResult
+
+FIXTURE = Path(__file__).parents[1] / "dsn" / "fixtures" / "crossing_2net.dsn"
+# rule: 2000 um wide traces, 2000 um clearance; NET_A runs along y = -40000
+A = RoutedWire(layer="Top", width=2000, coords=[2000, -40000, 198000, -40000])
+
+
+def _check(b_wire):
+    result = RoutingResult()
+    result.add_wire("NET_A", A)
+    result.add_wire("NET_B", b_wire)
+    return verify_result(parse_dsn(FIXTURE.read_text()), result)
+
+
+def test_a_crossing_on_one_layer_is_a_short():
+    report = _check(RoutedWire(layer="Top", width=2000, coords=[100000, -15000, 100000, -65000]))
+    assert report.shorts == 1 and report.clearance == 0
+    found = report.short_examples[0]
+    assert {found.net, found.other} == {"NET_A", "NET_B"} and found.layer == "Top"
+    assert abs(found.x_mm - 100.0) < 1.5 and abs(found.y_mm + 40.0) < 1.5
+
+
+def test_copper_closer_than_the_rule_is_a_clearance_violation():
+    # edges 1500 um apart against a 2000 um rule
+    report = _check(RoutedWire(layer="Top", width=2000, coords=[50000, -36500, 150000, -36500]))
+    assert report.shorts == 0 and report.clearance == 1
+
+
+def test_exactly_the_clearance_apart_is_clean():
+    report = _check(RoutedWire(layer="Top", width=2000, coords=[50000, -36000, 150000, -36000]))
+    assert report.clean
+
+
+def test_a_crossing_on_another_layer_is_clean():
+    report = _check(RoutedWire(layer="Bottom", width=2000, coords=[100000, -15000, 100000, -65000]))
+    assert report.clean
@@ -5,8 +5,8 @@ from __future__ import annotations
 import itertools
 import math

-from freeroute.dsn import parse_dsn
-from freeroute.route.pipeline import route_dsn_board_exact
+from rpmroute.dsn import parse_dsn
+from rpmroute.route.pipeline import route_dsn_board_exact

 # four GND pads 0.5 mm apart over a GND plane: each drops a via to the plane
 _DSN = """(pcb holes (parser) (resolution um 10) (unit um)
@@ -57,9 +57,9 @@ def test_connections_sharing_a_plane_via_write_it_once():


 def _router(dsn_text, via_drill_um=300):
-    from freeroute.board import build_board
-    from freeroute.route.grid_router import GridRouter
-    from freeroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn
+    from rpmroute.board import build_board
+    from rpmroute.route.grid_router import GridRouter
+    from rpmroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn

    dsn = parse_dsn(dsn_text)
    s = dsn.resolution.value
@@ -90,7 +90,7 @@ def test_no_via_goes_near_a_through_hole_pads_hole_even_of_its_own_net():


 def test_a_via_in_a_pad_keeps_hole_spacing_from_a_fixed_via():
-    from freeroute.geometry import IntPoint
+    from rpmroute.geometry import IntPoint

    text = _THT.replace("(network (net SIG (pins J1-1))))",
                        "(network (net SIG (pins J1-1)))\n"
@@ -0,0 +1,128 @@
+"""Window re-route: a finer grid around a stuck connection, kept only when
+it leaves fewer connections unrouted."""
+
+from __future__ import annotations
+
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.geometry import IntBox
+from rpmroute.route.grid_router import GridRouter
+from rpmroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn, route_dsn_board_exact
+
+
+def _slot(gap: int = 640, far: bool = False) -> str:
+    """A wall across the board with a slot in it. A trace fits the slot
+    only along a narrow band of heights that the board's 1x grid has no row
+    in and a 4x grid does. ``far`` adds a second net nowhere near the wall."""
+    yc = -5000
+    lo, hi = yc - gap // 2, yc + gap // 2
+    extra_place = "(place Q1 2000 -1000 front 0) (place Q2 6000 -1000 front 0)" if far else ""
+    extra_net = "(net M (pins Q1-1 Q2-1))" if far else ""
+    return f"""(pcb "slot.dsn"
+  (parser (string_quote ") (space_in_quoted_tokens on) (host_cad "t") (host_version "1"))
+  (resolution um 10)
+  (unit um)
+  (structure
+    (layer F.Cu (type signal) (property (index 0)))
+    (boundary (path pcb 0  0 0  20000 0  20000 -10000  0 -10000  0 0))
+    (keepout "" (rect F.Cu 9000 -10000 11000 {lo}))
+    (keepout "" (rect F.Cu 9000 {hi} 11000 0))
+    (rule (width 200) (clearance 200))
+  )
+  (library
+    (padstack Rect_Pad (shape (rect F.Cu -100 -100 100 100)) (attach off))
+    (image PAD (pin Rect_Pad 1 0 0))
+  )
+  (placement
+    (component PAD
+      (place P1 3000 {yc} front 0)
+      (place P2 17000 {yc} front 0)
+      {extra_place}
+    )
+  )
+  (network
+    (net N (pins P1-1 P2-1))
+    {extra_net}
+    (class default (rule (width 200) (clearance 200)))
+  )
+  (wiring)
+)
+"""
+
+
+def _route(text: str, rounds: int, **window):
+    exact, _scale, _layers = route_dsn_board_exact(
+        parse_dsn(text), resolution=1, window_reroute=rounds, window_resolution=4, **window,
+    )
+    return exact.result
+
+
+def test_the_board_grid_misses_the_slot_and_a_finer_window_finds_it():
+    plain = _route(_slot(), 0)
+    assert len(plain.failed) == 1
+    windowed = _route(_slot(), 1)
+    assert windowed.failed == []
+    assert windowed.wires  # and the copper it found is in the result
+
+
+def test_a_window_that_cannot_help_leaves_the_board_as_it_was():
+    plain = _route(_slot(gap=500, far=True), 0)  # too narrow for any grid
+    windowed = _route(_slot(gap=500, far=True), 2)
+    assert len(windowed.failed) == len(plain.failed) == 1
+    assert windowed.wires == plain.wires
+    assert windowed.vias == plain.vias
+
+
+def test_copper_outside_the_window_is_kept_as_it_was():
+    plain = _route(_slot(far=True), 0)
+    windowed = _route(_slot(far=True), 1)
+    assert windowed.failed == []
+    far_net = 2  # M, the second net in the DSN
+    assert windowed.wires[far_net] == plain.wires[far_net]
+
+
+def test_a_router_limited_to_some_nets_and_a_box_builds_only_those():
+    dsn = parse_dsn(_slot(far=True))
+    s = dsn.resolution.value
+    board = build_board(dsn)
+    whole = GridRouter(board, trace_width=round(_rule_width_dsn(dsn) * s),
+                       clearance=round(_rule_clearance_dsn(dsn) * s), orthogonal=True)
+    part = GridRouter(board, trace_width=round(_rule_width_dsn(dsn) * s),
+                      clearance=round(_rule_clearance_dsn(dsn) * s), orthogonal=True,
+                      only_nets=frozenset({2}), bounds=IntBox(0, -20000, 80000, 0))
+    assert {c.net_no for c in whole._build_connections()} == {1, 2}
+    assert {c.net_no for c in part._build_connections()} == {2}
+    assert part.cols * part.rows < whole.cols * whole.rows
+
+
+def test_a_spent_budget_starts_no_window():
+    assert len(_route(_slot(), 1, window_budget=0.0).failed) == 1
+    assert _route(_slot(), 1, window_budget=1000.0).failed == []
+
+
+def test_window_board_keeps_far_items_of_the_rerouted_nets_only():
+    from rpmroute.route.window import _item_box, _window_board
+
+    board = build_board(parse_dsn(_slot(far=True)))
+    items = [(item, _item_box(item)) for item in board.get_items()]
+    view = IntBox(80000, -60000, 120000, -40000)  # around the slot, far from Q1/Q2
+    sub = _window_board(board, items, view, {1}, {}, set(), {}, 100, 300, 300, [0], "via")
+    refs = {p.component_ref for p in sub.get_pins()}
+    assert {"P1", "P2"} <= refs  # net N's pins, though outside the view
+    assert not refs & {"Q1", "Q2"}  # net M's, far away, left out
+
+
+def test_a_connection_ending_outside_the_window_gets_no_copper():
+    """Its far end has no grid cells; a stub out to it would cross items the
+    window board never saw."""
+    from rpmroute.route.exact_router import route_board_exact
+
+    dsn = parse_dsn(_slot(far=True))
+    s = dsn.resolution.value
+    window = IntBox(70000, -70000, 130000, -30000)  # the slot only; net M's pins are far off
+    result = route_board_exact(
+        build_board(dsn), trace_width=round(_rule_width_dsn(dsn) * s),
+        clearance=round(_rule_clearance_dsn(dsn) * s), only_nets=frozenset({2}), bounds=window,
+    ).result
+    assert [f[0] for f in result.failed] == [2]
+    assert not result.wires.get(2) and not result.vias.get(2)
@@ -2,7 +2,7 @@

 from __future__ import annotations

-from freeroute.ses.indent import Identifier, IndentWriter
+from rpmroute.ses.indent import Identifier, IndentWriter


 def test_nested_scopes_indent_by_two_spaces():
@@ -1,7 +1,7 @@
 """End-to-end tests for the SES writer.

 Where possible these re-parse the emitted SES with the project's own tokenizer /
-S-expression parser (:mod:`freeroute.dsn.sexp`) and assert structural
+S-expression parser (:mod:`rpmroute.dsn.sexp`) and assert structural
 invariants, mirroring what FreeRouting's ``SesReader`` and ``kicad-cli pcb
 import specctra-ses`` walk: ``session > routes > network_out > net >
 wire(path)/via``.
@@ -13,9 +13,9 @@ from pathlib import Path

 import pytest

-from freeroute.dsn import parse_dsn
-from freeroute.dsn.sexp import SExp, parse
-from freeroute.ses import RoutedVia, RoutedWire, RoutingResult, write_ses
+from rpmroute.dsn import parse_dsn
+from rpmroute.dsn.sexp import SExp, parse
+from rpmroute.ses import RoutedVia, RoutedWire, RoutingResult, write_ses

 FIXTURES = Path(__file__).parent.parent / "dsn" / "fixtures"

@@ -142,7 +142,7 @@ def test_round_trip_from_empty_board_fixture():

 # --- SES coordinate units ---------------------------------------------------
 # FreeRouting's SesWriter writes coordinates in resolution units, and KiCad's
-# importer and mckicad's ses_apply read them that way. On 2026-09-26 freeroute
+# importer and mckicad's ses_apply read them that way. On 2026-09-26 rpmroute
 # was found writing DSN units instead, so every routed board came back 10x small.


@@ -155,8 +155,8 @@ def test_round_trip_from_empty_board_fixture():
    ],
 )
 def test_ses_scale(resolution, unit, expected):
-    from freeroute.dsn import parse_dsn
-    from freeroute.ses.writer import ses_scale
+    from rpmroute.dsn import parse_dsn
+    from rpmroute.ses.writer import ses_scale

    dsn = parse_dsn(f"(pcb t (parser) {resolution} {unit} (structure) (placement) (library) (network))")
    assert ses_scale(dsn) == pytest.approx(expected)
@@ -1,4 +1,4 @@
-"""Tests for the freeroute CLI (Specctra DSN in, SES out).
+"""Tests for the rpmroute CLI (Specctra DSN in, SES out).

 Covers the engine selection contract: every engine must route a fixture from the
 command line, and every option the selected engine does not implement must fail
@@ -11,7 +11,7 @@ from pathlib import Path

 import pytest

-from freeroute.cli import ENGINE_OPTIONS, main
+from rpmroute.cli import ENGINE_OPTIONS, main

 FIXTURES = Path(__file__).parent / "dsn" / "fixtures"
 FIXTURE = FIXTURES / "simple_2net.dsn"
@@ -71,13 +71,39 @@ def test_cli_every_engine_routes_a_fixture(engine, tmp_path):
    assert "(wire" in text


-def test_cli_default_engine_is_grid(tmp_path):
-    """The default must stay grid — the drop-in JAR replacement behaviour."""
+def test_cli_default_engine_is_exact(tmp_path):
+    """The default is the engine that checks its copper: grid output can short
+    and say nothing (a user routing with no flags shipped 15 crossings)."""
    default = tmp_path / "default.ses"
-    grid = tmp_path / "grid.ses"
+    exact = tmp_path / "exact.ses"
    assert main([str(FIXTURE), "-do", str(default)]) == 0
-    assert main([str(FIXTURE), "--engine", "grid", "-do", str(grid)]) == 0
-    assert default.read_text() == grid.read_text()
+    assert main([str(FIXTURE), "--engine", "exact", "-do", str(exact)]) == 0
+    assert default.read_text() == exact.read_text()
+
+
+@pytest.mark.parametrize("engine", ["grid", "room"])
+def test_unchecked_engines_are_checked_after_routing(tmp_path, capsys, engine):
+    assert main([str(FIXTURE), "--engine", engine, "-do", str(tmp_path / "out.ses")]) == 0
+    assert f"{engine} output checked on exact shapes: 0 short(s), 0 clearance" in capsys.readouterr().err
+
+
+def test_strict_fails_a_run_whose_copper_is_not_clean(tmp_path, monkeypatch, capsys):
+    from rpmroute import cli
+    from rpmroute.route.verify import VerifyReport, Violation
+
+    bad = VerifyReport(shorts=1, short_examples=[Violation("A", "B", "F.Cu", 1.0, 2.0)])
+    monkeypatch.setattr(cli, "verify_result", lambda dsn, result: bad)
+    out = tmp_path / "out.ses"
+    assert main([str(FIXTURE), "--engine", "grid", "-do", str(out)]) == 0
+    assert main([str(FIXTURE), "--engine", "grid", "--strict", "-do", str(out)]) == 3
+    assert out.exists()  # the session is still written
+    err = capsys.readouterr().err
+    assert "short: A x B on F.Cu at (1.00, 2.00) mm" in err and "not DRC-clean" in err
+
+
+def test_the_exact_engine_does_not_warn(tmp_path, capsys):
+    assert main([str(FIXTURE), "-do", str(tmp_path / "out.ses")]) == 0
+    assert "WARNING" not in capsys.readouterr().err


 def test_cli_room_pack_routes(tmp_path):
@@ -161,6 +187,10 @@ def test_cli_supported_combinations_are_accepted(tmp_path):
        "negotiate": ["--negotiate", "2"],
        "rollback": ["--no-rollback"],
        "tree": ["--no-tree"],
+        "window": ["--window-reroute", "1"],
+        "vias": ["--reduce-vias"],
+        "via_cost": ["--via-cost", "40"],
+        "smooth": ["--smooth"],
    }
    for engine, options in ENGINE_OPTIONS.items():
        for option in options:
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
rsp2k	08a7ac7e49	Merge feat/smooth: opt-in --smooth turns grid staircases into octilinear runs after routing	2026-10-17 11:35:22 -06:00
rsp2k	34200f27ff	--smooth: no 45-degree leg shorter than two track widths A short diagonal at a wire's end is a kink beside its pad, and the pour refilled round it left a copper sliver (KiCad copper_sliver) on the TerraHawk lights node. Small offsets now stay square jogs; chamfers get the same floor.	2026-10-17 11:15:47 -06:00
rsp2k	c91ca1994c	--smooth: turn grid staircases into octilinear runs after routing A last stage on the finished result, wire by wire: a run of legs between two points becomes the octilinear shape joining them when its copper is clear, the furthest point first; right-angle corners left are chamfered; straight runs are merged. Ends, vias, points where another wire of the net meets the wire, and legs across own-net pads stay. Every new leg and corner is checked on the exact shapes against other nets, pads, keepouts and the board edge, slanted legs both ways round as the verifier counts a pair. A net whose pads end up joined differently is put back, and the whole smoothing is dropped if the finished check finds more violations than before. --smooth-report adds track length per layer.	2026-10-17 09:35:45 -06:00
rsp2k	f3c4618fbb	Merge feat/reduce-vias: opt-in --reduce-vias pass and --via-cost	2026-10-10 09:39:07 -06:00
rsp2k	fa20dc5623	Merge main into feat/reduce-vias	2026-10-07 20:54:02 -06:00
rsp2k	b9fed0fc4d	Merge feat/verify-output: check grid and room output on exact shapes, --strict	2026-10-07 20:12:51 -06:00
rsp2k	8cb7a627f0	Add --reduce-vias and --via-cost to the exact engine --reduce-vias is a last stage: each net that has vias is routed again on its own with vias made eight times dearer, everything else held as fixed copper (the window stage's board), and its new copper is kept only if the net fails nothing new and has fewer vias; the nets with the most vias go first, within a share of the routing's own time. --via-cost exposes the search's layer-change price (default 10 grid steps). bench.py records each run's via count and prints via totals per variant.	2026-10-07 20:06:00 -06:00
rsp2k	74d97b601c	Check grid and room output on exact shapes and report shorts The grid and room engines write copper they never check. After a grid or room run the result is now put through the exact engine's geometry (its pads, fixed copper and keepouts; wires as boxes or slanted slabs; vias as their pads) and the report gives the shorts and clearance violations, with examples, instead of a blanket warning. --strict exits 3 when there are any; by default the exit status stays 0 so the JAR drop-in contract holds. The exact engine's static-copper setup moves into insert_static_copper so both use it; exact runs are byte-identical before and after.	2026-10-07 20:04:04 -06:00
rsp2k	1852df3d53	Merge fix/default-exact: exact engine by default, warn on unchecked engines	2026-10-07 18:52:10 -06:00
rsp2k	33de21ba0e	Route with the exact engine by default; warn when an engine does not check The grid engine was the default and its copper is not checked against exact shapes: a full reroute of the Labrador lid with no flags came out with 15 tracks_crossing and 87 clearance violations under KiCad's DRC while the report listed only unrouted connections. The exact engine (what mckicad and every benchmark already use) is now the default, and grid or room runs end with a warning that their output needs a DRC.	2026-10-07 18:37:33 -06:00
rsp2k	3b29edc624	Merge feat/rename-rpmroute: the router is now rpmroute (freeroute kept as an alias)	2026-10-07 17:35:56 -06:00
rsp2k	a6aa1991a1	Rename to rpmroute The router began as a port of FreeRouting and has grown its own engine (negotiated congestion, tree nets, exact checks, axis escapes), and 'freeroute' was one letter from the project it no longer follows. The package, module and command are now rpmroute; the freeroute command stays as an alias, and the RPMROUTE / RPMROUTE_ORACLE_JAVA variables fall back to the old FREEROUTE names. Version 2026.10.07. Routing is unchanged: a PCBench board routes to a byte-identical session either way.	2026-10-07 14:10:36 -06:00
rsp2k	45aee463a8	Merge feat/window-reroute: opt-in --window-reroute, budgeted finer-grid windows around stuck connections	2026-10-07 14:00:39 -06:00
rsp2k	d1def2c4b9	Window boards: never search a connection ending outside the window With items away from the window left off its board, a stub from the window edge out to a rerouted net's far pin crossed copper the exact check never saw: 38 shorts on th-eda's flight controller. A connection with an end outside the bounds is now left unrouted, and a window whose new copper leaves the window is refused.	2026-10-06 23:07:09 -06:00
rsp2k	28523bcbac	Window re-route: time budget, window cap, smallest first, window boards A window's board now holds every pin and piece of copper of the nets it reroutes and, of the rest, only items near the window, instead of the whole board rebuilt per window. The smallest windows go first, at most --window-cap per round (40), and no window starts once --window-budget of the routing's own time is spent (0.25). On th-eda's flight controller the stage had taken 12x the routing time for no gain.	2026-10-06 22:51:51 -06:00
rsp2k	27f7202d2f	--window-reroute N: route a finer grid around each connection still stuck After the exact engine, every net routed wholly inside a window around a stuck connection's pins is ripped, the rest of the board is laid down as fixed copper, and the window alone is routed again at --window-resolution (default 4) with the stuck net and the ripped nets only. The result is kept only if fewer connections are left unrouted; each round doubles the margin. The grid and exact routers gain only_nets and bounds for it. Off by default.	2026-10-06 15:04:02 -06:00
rsp2k	95c89032e3	Merge feat/tree-nets: multi-pin nets route as trees, legs tee into routed copper	2026-10-05 17:12:32 -06:00