fix: gate dev-error routes centrally and exclude from breadcrumbs

src/app/dashboard/dev-errors/boundary-error/page.tsx

@@ -1,13 +1,6 @@
-import { notFound } from "next/navigation";
 import TriggerBoundaryError from "./TriggerBoundaryError";
 
-const DEV_ERRORS_ENABLED = process.env.NODE_ENV !== "production";
-
 export default function DashboardBoundaryErrorPage() {
-  if (!DEV_ERRORS_ENABLED) {
-    notFound();
-  }
-
   return (
     <main className="space-y-4">
       <h1 className="text-2xl font-semibold text-text-primary">

src/app/dashboard/dev-errors/layout.tsx

@@ -0,0 +1,19 @@
+import { notFound } from "next/navigation";
+import type { ReactNode } from "react";
+
+const DEV_ERRORS_ENABLED = process.env.NODE_ENV !== "production";
+
+export default function DevErrorsLayout({ children }: { children: ReactNode }) {
+  if (!DEV_ERRORS_ENABLED) {
+    notFound();
+  }
+
+  return (
+    <div className="rounded-lg border border-dashed border-yellow-500/40 bg-yellow-500/5 p-4">
+      <p className="mb-4 text-xs font-semibold uppercase tracking-wider text-yellow-400">
+        Internal — dev-only route
+      </p>
+      {children}
+    </div>
+  );
+}

src/app/dashboard/dev-errors/page.tsx

@@ -1,13 +1,6 @@
 import Link from "next/link";
-import { notFound } from "next/navigation";
-
-const DEV_ERRORS_ENABLED = process.env.NODE_ENV !== "production";
 
 export default function DashboardDevErrorsPage() {
-  if (!DEV_ERRORS_ENABLED) {
-    notFound();
-  }
-
   return (
     <main className="space-y-8">
       <header>

src/app/dashboard/dev-errors/route-error/page.tsx

@@ -1,11 +1,3 @@
-import { notFound } from "next/navigation";
-
-const DEV_ERRORS_ENABLED = process.env.NODE_ENV !== "production";
-
 export default function DashboardRouteErrorPage() {
-  if (!DEV_ERRORS_ENABLED) {
-    notFound();
-  }
-
   throw new Error("Intentional dashboard route error for boundary testing");
 }

src/lib/routeMetadata.test.ts

@@ -200,3 +200,11 @@ test("breadcrumbs for docs/tokens path are correct", () => {
     ["Home", "Docs", "Design Tokens"],
   );
 });
+
+test("breadcrumbs skip devOnly routes", () => {
+  const breadcrumbs = buildBreadcrumbsFromPath("/dashboard/dev-errors/boundary-error");
+  const labels = breadcrumbs.map((b) => b.label);
+  assert.ok(!labels.includes("Dev Errors"), "dev-errors should not appear in breadcrumbs");
+  assert.ok(!labels.includes("Boundary Error"), "boundary-error should not appear in breadcrumbs");
+  assert.deepEqual(labels, ["Home", "Dashboard"]);
+});

src/lib/routeMetadata.tsx

@@ -240,6 +240,10 @@ export function getRouteLabel(pathname: string, fallback = "Dashboard"): string
 export function buildBreadcrumbsFromPath(
   pathname: string,
 ): import("@/types/breadcrumb.types").BreadcrumbItem[] {
+  const devOnlyHrefs = new Set(
+    appRouteDefinitions.filter((d) => d.devOnly).map((d) => d.href),
+  );
+
   const segments = pathname.split("/").filter(Boolean);
   const items: import("@/types/breadcrumb.types").BreadcrumbItem[] = [
     { label: "Home", href: "/", icon: routeMetadata["/"]?.icon },
@@ -248,6 +252,11 @@ export function buildBreadcrumbsFromPath(
   let cumulative = "";
   segments.forEach((seg, idx) => {
     cumulative += `/${seg}`;
+
+    if (devOnlyHrefs.has(cumulative)) {
+      return;
+    }
+
     const meta = routeMetadata[cumulative];
     items.push({
       label: meta?.label ?? seg.charAt(0).toUpperCase() + seg.slice(1),