Ignore gap-fill regions narrower than the trace width

lib/RectDiffPipeline.ts

@@ -77,6 +77,8 @@ export class RectDiffPipeline extends BasePipelineSolver<RectDiffPipelineInput>
               rectDiffPipeline.inputProblem.simpleRouteJson.layerCount || 0,
           },
           maxGapFillPasses: rectDiffPipeline.inputProblem.maxGapFillPasses,
+          minTraceWidth:
+            rectDiffPipeline.inputProblem.simpleRouteJson.minTraceWidth,
         },
       ],
     ),

lib/solvers/GapFillSolver/ExpandEdgesToEmptySpaceSolver.ts

@@ -79,6 +79,7 @@ const getDistanceToBoardEdge = (
 export type ExpandEdgesToEmptySpaceSolverInput = {
   /** Optional for standalone callers; the full board pipeline always supplies it. */
   bounds?: Bounds
+  minTraceWidth?: number
   inputMeshNodes: CapacityMeshNode[]
   segmentsWithAdjacentEmptySpace: Array<SegmentWithAdjacentEmptySpace>
   boardVoid?: {
@@ -261,6 +262,11 @@ export class ExpandEdgesToEmptySpaceSolver extends BaseSolver {
     const nodeWidth = nodeBounds.maxX - nodeBounds.minX
     const nodeHeight = nodeBounds.maxY - nodeBounds.minY
 
+    const minRoutableDimension = Math.max(EPS, this.input.minTraceWidth ?? 0)
+    if (nodeWidth < minRoutableDimension || nodeHeight < minRoutableDimension) {
+      return
+    }
+
     const expandedSegment = {
       segment,
       newNode: {
@@ -274,11 +280,6 @@ export class ExpandEdgesToEmptySpaceSolver extends BaseSolver {
     }
     this.lastExpandedSegment = expandedSegment
 
-    if (nodeWidth < EPS || nodeHeight < EPS) {
-      // Node is too small, skipping
-      return
-    }
-
     this.expandedSegments.push(expandedSegment)
     this.rectSpatialIndex.insert({
       ...expandedSegment.newNode,

lib/solvers/GapFillSolver/GapFillSolverPipeline.ts

@@ -27,6 +27,7 @@ type GapFillSolverInput = {
    * expanded nodes; values below 1 are clamped to 1.
    */
   maxGapFillPasses: number
+  minTraceWidth: number
 }
 
 type GapFillOutput = {
@@ -75,6 +76,7 @@ export class GapFillSolverPipeline extends BasePipelineSolver<GapFillSolverInput
               .segmentsWithAdjacentEmptySpace,
           boardVoid: gapFillPipeline.inputProblem.boardVoid,
           bounds: gapFillPipeline.inputProblem.bounds,
+          minTraceWidth: gapFillPipeline.inputProblem.minTraceWidth,
         },
       ],
       {

tests/gap-fill-board-bounds.test.ts

@@ -48,6 +48,7 @@ test("bounded recursive gap filling keeps useful space and respects blockers", (
     bounds,
     meshNodes: [parent, blocker],
     maxGapFillPasses: 3,
+    minTraceWidth: 0.1,
   })
   solver.solve()
   const generated = solver

tests/solver/repros/pmp22650-unroutable-gap-fill/pmp22650-unroutable-gap-fill.test.ts

@@ -34,6 +34,7 @@ const platedHoleRegion: CapacityMeshNode = {
 
 test("PMP22650 does not fill a gap narrower than minTraceWidth", async () => {
   const solver = new ExpandEdgesToEmptySpaceSolver({
+    minTraceWidth: 0.1,
     inputMeshNodes: [lowerRegion, upperRegion, platedHoleRegion],
     segmentsWithAdjacentEmptySpace: [
       {
@@ -51,11 +52,7 @@ test("PMP22650 does not fill a gap narrower than minTraceWidth", async () => {
   const expandedNodes = solver
     .getOutput()
     .expandedSegments.map(({ newNode }) => newNode)
-  expect(expandedNodes).toHaveLength(1)
-  expect(expandedNodes[0]).toMatchObject({
-    width: 5.059939270000001,
-    height: 0.002759999999966567,
-  })
+  expect(expandedNodes).toHaveLength(0)
   const verticalScale = 40
   await expect(
     getSvgFromGraphicsObject(