Support immutable routes during trace simplification

lib/solvers/SameNetViaMergerSolver/SameNetViaMergerSolver.ts

@@ -14,6 +14,8 @@ import { segmentToBoxMinDistance } from "@tscircuit/math-utils"
 
 export interface SameNetViaMergerSolverInput {
   inputHdRoutes: HighDensityRoute[]
+  /** Routed copper that participates in collision checks but is never changed. */
+  otherHdRoutes?: ReadonlyArray<HighDensityRoute>
   obstacles: Obstacle[]
   colorMap: Record<string, string>
   layerCount: number
@@ -37,7 +39,11 @@ const getNetForRoute = (
   connMap: ConnectivityMap,
   route: HighDensityRoute,
 ): string => {
-  const net = connMap.idToNetMap[route.connectionName]
+  const net =
+    connMap.idToNetMap[route.connectionName] ??
+    (route.rootConnectionName
+      ? connMap.idToNetMap[route.rootConnectionName]
+      : undefined)
   if (!net) {
     throw new Error(
       `SameNetViaMergerSolver could not find net for route "${route.connectionName}"`,
@@ -170,6 +176,13 @@ export class SameNetViaMergerSolver extends BaseSolver {
   obstacleSHI: ObstacleSpatialHashIndex
   hdRouteSHI: HighDensityRouteSpatialIndex
 
+  private createHdRouteSpatialIndex(): HighDensityRouteSpatialIndex {
+    return new HighDensityRouteSpatialIndex([
+      ...this.mergedViaHdRoutes,
+      ...(this.input.otherHdRoutes ?? []),
+    ])
+  }
+
   constructor(private input: SameNetViaMergerSolverInput) {
     super()
     if (!input.connMap) {
@@ -192,7 +205,7 @@ export class SameNetViaMergerSolver extends BaseSolver {
       "flatbush",
       this.input.obstacles,
     )
-    this.hdRouteSHI = new HighDensityRouteSpatialIndex(this.inputHdRoutes)
+    this.hdRouteSHI = this.createHdRouteSpatialIndex()
     this.vias = []
     this.offendingVias = []
     this.connMap = input.connMap
@@ -444,7 +457,7 @@ export class SameNetViaMergerSolver extends BaseSolver {
       }
     }
     this.rebuildVias()
-    this.hdRouteSHI = new HighDensityRouteSpatialIndex(this.mergedViaHdRoutes)
+    this.hdRouteSHI = this.createHdRouteSpatialIndex()
     this.stats.mergedViaGroups = groups.length
     this.stats.mergedViaCount = mergedViaCount
   }

lib/solvers/SimplifiedPathSolver/MultiSimplifiedPathSolver.ts

@@ -20,6 +20,7 @@ export class MultiSimplifiedPathSolver extends BaseSolver {
   activeSubSolver: SingleSimplifiedPathSolver | null = null
 
   unsimplifiedHdRoutes: HighDensityIntraNodeRoute[]
+  otherHdRoutes: ReadonlyArray<HighDensityIntraNodeRoute>
   obstacles: Obstacle[]
   connMap: ConnectivityMap
   colorMap: Record<string, string>
@@ -28,6 +29,8 @@ export class MultiSimplifiedPathSolver extends BaseSolver {
 
   constructor(params: {
     unsimplifiedHdRoutes: HighDensityIntraNodeRoute[]
+    /** Routed copper that participates in collision checks but is never changed. */
+    otherHdRoutes?: ReadonlyArray<HighDensityIntraNodeRoute>
     obstacles: Obstacle[]
     connMap?: ConnectivityMap
     colorMap?: Record<string, string>
@@ -38,11 +41,12 @@ export class MultiSimplifiedPathSolver extends BaseSolver {
     this.MAX_ITERATIONS = 100e6
 
     this.unsimplifiedHdRoutes = params.unsimplifiedHdRoutes
+    this.otherHdRoutes = params.otherHdRoutes ?? []
     const inferredLayerCount =
       Math.max(
         2,
-        ...params.unsimplifiedHdRoutes.flatMap((r) =>
-          r.route.map((p) => p.z + 1),
+        ...[...params.unsimplifiedHdRoutes, ...this.otherHdRoutes].flatMap(
+          (r) => r.route.map((p) => p.z + 1),
         ),
       ) || 2
     this.obstacles = createObjectsWithZLayers(
@@ -68,9 +72,11 @@ export class MultiSimplifiedPathSolver extends BaseSolver {
 
       this.activeSubSolver = new SingleSimplifiedPathSolver5({
         inputRoute: hdRoute,
-        otherHdRoutes: this.unsimplifiedHdRoutes
-          .slice(this.currentUnsimplifiedHdRouteIndex + 1)
-          .concat(this.simplifiedHdRoutes),
+        otherHdRoutes: this.otherHdRoutes.concat(
+          this.unsimplifiedHdRoutes
+            .slice(this.currentUnsimplifiedHdRouteIndex + 1)
+            .concat(this.simplifiedHdRoutes),
+        ),
         obstacles: this.obstacles,
         connMap: this.connMap,
         colorMap: this.colorMap,

lib/solvers/SimplifiedPathSolver/SingleSimplifiedPathSolver5_Deg45.ts

@@ -69,6 +69,25 @@ export class SingleSimplifiedPathSolver5 extends SingleSimplifiedPathSolver {
 
   TAIL_JUMP_RATIO: number = 0.8
 
+  private isSameNetRoute(otherRoute: HighDensityIntraNodeRoute): boolean {
+    const inputRouteIds = [
+      this.inputRoute.connectionName,
+      this.inputRoute.rootConnectionName,
+    ].filter((id): id is string => id !== undefined)
+    const otherRouteIds = [
+      otherRoute.connectionName,
+      otherRoute.rootConnectionName,
+    ].filter((id): id is string => id !== undefined)
+
+    return inputRouteIds.some((inputRouteId) =>
+      otherRouteIds.some(
+        (otherRouteId) =>
+          inputRouteId === otherRouteId ||
+          this.connMap.areIdsConnected(inputRouteId, otherRouteId),
+      ),
+    )
+  }
+
   constructor(
     params: ConstructorParameters<typeof SingleSimplifiedPathSolver>[0],
   ) {
@@ -130,12 +149,7 @@ export class SingleSimplifiedPathSolver5 extends SingleSimplifiedPathSolver {
 
     this.filteredObstaclePathSegments = this.otherHdRoutes.flatMap(
       (hdRoute) => {
-        if (
-          this.connMap.areIdsConnected(
-            this.inputRoute.connectionName,
-            hdRoute.connectionName,
-          )
-        ) {
+        if (this.isSameNetRoute(hdRoute)) {
           return []
         }
 
@@ -158,12 +172,7 @@ export class SingleSimplifiedPathSolver5 extends SingleSimplifiedPathSolver {
     this.segmentTree = new SegmentTree(this.filteredObstaclePathSegments)
 
     this.filteredVias = this.otherHdRoutes.flatMap((hdRoute) => {
-      if (
-        this.connMap.areIdsConnected(
-          this.inputRoute.connectionName,
-          hdRoute.connectionName,
-        )
-      ) {
+      if (this.isSameNetRoute(hdRoute)) {
         return []
       }
 
@@ -256,12 +265,7 @@ export class SingleSimplifiedPathSolver5 extends SingleSimplifiedPathSolver {
 
     // Collect jumper pads from other routes as obstacles
     this.filteredJumperPads = this.otherHdRoutes.flatMap((hdRoute) => {
-      if (
-        this.connMap.areIdsConnected(
-          this.inputRoute.connectionName,
-          hdRoute.connectionName,
-        )
-      ) {
+      if (this.isSameNetRoute(hdRoute)) {
         return []
       }
 

lib/solvers/TraceSimplificationSolver/TraceSimplificationSolver.ts

@@ -71,6 +71,7 @@ export class TraceSimplificationSolver extends BaseSolver {
    *   - defaultViaDiameter: Default diameter for vias
    *   - layerCount: Number of routing layers
    *   - minTraceToPadEdgeClearance: Minimum trace-edge clearance to pads/vias
+   *   - otherHdRoutes: Immutable routed traces to avoid while simplifying
    *   - iterations: Number of complete simplification iterations (default: 2)
    */
   constructor(
@@ -83,6 +84,7 @@ export class TraceSimplificationSolver extends BaseSolver {
       readonly defaultViaDiameter: number
       readonly layerCount: number
       readonly minTraceToPadEdgeClearance?: number
+      readonly otherHdRoutes?: ReadonlyArray<HighDensityRoute>
     },
   ) {
     super()
@@ -229,6 +231,7 @@ export class TraceSimplificationSolver extends BaseSolver {
         case "via_removal":
           this.activeSubSolver = new UselessViaRemovalSolver({
             unsimplifiedHdRoutes: this.hdRoutes,
+            otherHdRoutes: [...(this.simplificationConfig.otherHdRoutes ?? [])],
             obstacles: [...this.simplificationConfig.obstacles],
             colorMap: { ...this.simplificationConfig.colorMap },
             layerCount: this.simplificationConfig.layerCount,
@@ -250,6 +253,7 @@ export class TraceSimplificationSolver extends BaseSolver {
         case "via_merging":
           this.activeSubSolver = new SameNetViaMergerSolver({
             inputHdRoutes: this.hdRoutes,
+            otherHdRoutes: [...(this.simplificationConfig.otherHdRoutes ?? [])],
             obstacles: [...this.simplificationConfig.obstacles],
             colorMap: { ...this.simplificationConfig.colorMap },
             layerCount: this.simplificationConfig.layerCount,
@@ -265,6 +269,7 @@ export class TraceSimplificationSolver extends BaseSolver {
         case "path_simplification":
           this.activeSubSolver = new MultiSimplifiedPathSolver({
             unsimplifiedHdRoutes: this.hdRoutes,
+            otherHdRoutes: [...(this.simplificationConfig.otherHdRoutes ?? [])],
             obstacles: [...this.simplificationConfig.obstacles],
             connMap: this.simplificationConfig.connMap,
             colorMap: { ...this.simplificationConfig.colorMap },
@@ -327,6 +332,38 @@ export class TraceSimplificationSolver extends BaseSolver {
       })
     }
 
+    // Draw immutable routed copper as subdued, dashed layer-colored peers.
+    for (const route of this.simplificationConfig.otherHdRoutes ?? []) {
+      for (let i = 0; i < route.route.length - 1; i++) {
+        const current = route.route[i]
+        const next = route.route[i + 1]
+        if (current.z !== next.z) continue
+
+        visualization.lines.push({
+          points: [
+            { x: current.x, y: current.y },
+            { x: next.x, y: next.y },
+          ],
+          strokeColor:
+            current.z === 0
+              ? "rgba(160, 32, 32, 0.55)"
+              : "rgba(32, 32, 160, 0.55)",
+          strokeWidth: route.traceThickness,
+          strokeDash: [0.08, 0.08],
+          label: `${route.connectionName} immutable (z=${current.z})`,
+        })
+      }
+
+      for (const via of route.vias) {
+        visualization.circles.push({
+          center: { x: via.x, y: via.y },
+          radius: route.viaDiameter / 2,
+          fill: "rgba(96, 96, 96, 0.45)",
+          label: `${route.connectionName} immutable via`,
+        })
+      }
+    }
+
     // Draw output routes and vias
     for (const route of this.hdRoutes) {
       if (route.route.length === 0) continue

lib/solvers/UselessViaRemovalSolver/UselessViaRemovalSolver.ts

@@ -13,6 +13,8 @@ import type { ConnectivityMap } from "circuit-json-to-connectivity-map"
 
 export interface UselessViaRemovalSolverInput {
   unsimplifiedHdRoutes: HighDensityRoute[]
+  /** Routed copper that participates in collision checks but is never changed. */
+  otherHdRoutes?: ReadonlyArray<HighDensityRoute>
   obstacles: Obstacle[]
   colorMap: Record<string, string>
   layerCount: number
@@ -52,9 +54,10 @@ export class UselessViaRemovalSolver extends BaseSolver {
       "flatbush",
       this.input.obstacles,
     )
-    this.hdRouteSHI = new HighDensityRouteSpatialIndex(
-      this.unsimplifiedHdRoutes,
-    )
+    this.hdRouteSHI = new HighDensityRouteSpatialIndex([
+      ...this.unsimplifiedHdRoutes,
+      ...(input.otherHdRoutes ?? []),
+    ])
   }
 
   _step() {