fix(fanout): keep the routing area consistent with the fanout boundary

fanoutBoundaryPadding moves the boundary the fanout terminates on, but
simpleRouteJson.bounds was left at its earlier value, so every exit ended up
outside the region copper may occupy. The routing area now widens to contain
the resolved fanout bounds.

Adds a descriptive error for the case where the two are still inconsistent,
rather than letting the fanout silently route nothing.

Two breakout snapshots shift slightly: the routable area is marginally larger,
so one 45-degree bend and a pair of plane-fanout vias move a fraction. Routes
are otherwise unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: seveibar

lib/components/primitive-components/Group/Group.ts

@@ -1238,6 +1238,18 @@ export class Group<Props extends z.ZodType<any, any, any> = typeof groupProps>
           },
         )
         const { fanoutBounds, routingPcbGroupId } = routingPhasePlan
+        if (fanoutBounds) {
+          // The fanout terminates exactly on these bounds, so the routing area
+          // has to contain them. fanoutBoundaryPadding moves the boundary
+          // without touching simpleRouteJson.bounds, which would otherwise
+          // leave every exit sitting outside the area copper may occupy.
+          simpleRouteJson.bounds = {
+            minX: Math.min(simpleRouteJson.bounds.minX, fanoutBounds.minX),
+            maxX: Math.max(simpleRouteJson.bounds.maxX, fanoutBounds.maxX),
+            minY: Math.min(simpleRouteJson.bounds.minY, fanoutBounds.minY),
+            maxY: Math.max(simpleRouteJson.bounds.maxY, fanoutBounds.maxY),
+          }
+        }
         if (fanoutBounds && routingPcbGroupId) {
           db.pcb_group.update(routingPcbGroupId, {
             center: {

lib/utils/autorouting/FanoutAutorouter.ts

@@ -415,6 +415,23 @@ export class FanoutAutorouter implements GenericLocalAutorouter {
     debugGraphics: AutorouterProgressEvent["debugGraphics"]
   } {
     const fanoutSolverOptions = this.getFanoutSolverOptions()
+    const sharedBoundary =
+      this.options.fanoutBounds ?? fanoutSolverOptions.sharedBoundary
+    if (sharedBoundary) {
+      const { bounds } = this.input
+      const outsideBy = Math.max(
+        bounds.minX - sharedBoundary.minX,
+        sharedBoundary.maxX - bounds.maxX,
+        bounds.minY - sharedBoundary.minY,
+        sharedBoundary.maxY - bounds.maxY,
+      )
+      if (outsideBy > 1e-6) {
+        throw new Error(
+          `Fanout boundary extends ${Math.round(outsideBy * 1000) / 1000}mm outside the routable area, so its escapes would have to terminate where copper cannot go. ` +
+            "This usually means the fanout boundary was widened without widening the routing bounds to match.",
+        )
+      }
+    }
     const fanoutSolver = new FanoutSolver(
       this.input as unknown as ConstructorParameters<typeof FanoutSolver>[0],
       {