Fix(differentials): route "Compare selected" directly to resolved presentation workflow

src/app/differentials/presentations/route.ts

@@ -2,20 +2,30 @@ import { type NextRequest, NextResponse } from "next/server";
 
 import { getPresentationWorkflowSelectionForDiagnosisIds } from "@/lib/differentials";
 
-export function GET(request: NextRequest) {
+function presentationsRedirectLocation(request: NextRequest) {
   const query = (request.nextUrl.searchParams.get("query") ?? request.nextUrl.searchParams.get("q"))?.trim();
   const selectedIds = (request.nextUrl.searchParams.get("ids") ?? "")
     .split(",")
     .map((id) => id.trim())
     .filter(Boolean);
   const selection = getPresentationWorkflowSelectionForDiagnosisIds(selectedIds);
-  const destination = new URL(
-    `/differentials/presentations/${selection?.workflow.id ?? "acute-confusion-encephalopathy"}`,
-    request.url,
-  );
-  if (query) destination.searchParams.set("q", query);
-  if (selection?.diagnosisIds.length) destination.searchParams.set("ids", selection.diagnosisIds.join(","));
-  return NextResponse.redirect(destination);
+  const params = new URLSearchParams();
+  if (query) params.set("q", query);
+  if (selection?.diagnosisIds.length) params.set("ids", selection.diagnosisIds.join(","));
+  const pathname = `/differentials/presentations/${selection?.workflow.id ?? "acute-confusion-encephalopathy"}`;
+  const suffix = params.toString();
+  // Relative Location so redirects stay same-origin in the browser even when
+  // the server request URL uses a bind address like 0.0.0.0.
+  return suffix ? `${pathname}?${suffix}` : pathname;
+}
+
+export function GET(request: NextRequest) {
+  return new NextResponse(null, {
+    status: 307,
+    headers: {
+      Location: presentationsRedirectLocation(request),
+    },
+  });
 }
 
 export const HEAD = GET;

src/components/clinical-dashboard/differentials-home.tsx

@@ -30,6 +30,7 @@ import { useDifferentialSearch } from "@/components/clinical-dashboard/use-diffe
 import { useResultSort } from "@/components/use-result-sort";
 import { cn } from "@/components/ui-primitives";
 import { appModeHomeHref } from "@/lib/app-modes";
+import { differentialRouteWithQuery, differentialSelectedCompareHref } from "@/lib/differentials-navigation";
 import { differentialsMobileCompareAddonSlotId } from "@/lib/mode-home-composer";
 import {
   composeDifferentialSearchResults,
@@ -111,17 +112,6 @@ const candidateIconBySlug: Array<[string, LucideIcon]> = [
   ["delirium", BrainCircuit],
 ];
 
-function routeWithQuery(path: string, query: string, selectedIds?: Set<string>) {
-  const params = new URLSearchParams();
-  const trimmedQuery = query.trim();
-  if (trimmedQuery) params.set("q", trimmedQuery);
-  if (selectedIds && selectedIds.size > 0) {
-    params.set("ids", Array.from(selectedIds).join(","));
-  }
-  const suffix = params.toString();
-  return suffix ? `${path}?${suffix}` : path;
-}
-
 /**
  * Mobile/tablet floating compare action. Portals into the search composer's
  * addon slot so it stays anchored beside the active result controls, but
@@ -162,7 +152,7 @@ function DifferentialsMobileCompareBar({
     <div aria-live="polite" className="flex w-full justify-center">
       {hasSelection ? (
         <Link
-          href={routeWithQuery("/differentials/presentations", query, selectedIds)}
+          href={differentialSelectedCompareHref(query, selectedIds)}
           data-testid="differentials-compare-selected-mobile"
           className="inline-flex min-h-12 max-w-full items-center gap-2.5 rounded-full border border-[color:var(--clinical-accent)] bg-[color:var(--clinical-accent)] py-1 pl-4 pr-2.5 text-sm font-extrabold text-[color:var(--clinical-accent-contrast)] shadow-[var(--shadow-elevated)] transition active:bg-[color:var(--clinical-accent-hover)]"
         >
@@ -599,7 +589,7 @@ function SafetyCard({ safety, query }: { safety: string; query: string }) {
           </h2>
           <p className="mt-2 text-sm font-semibold leading-6 text-[color:var(--text-heading)]">{safety}</p>
           <Link
-            href={routeWithQuery("/differentials/presentations", query)}
+            href={differentialRouteWithQuery("/differentials/presentations", query)}
             className="mt-2 inline-flex min-h-tap items-center gap-1.5 text-sm font-bold text-[color:var(--clinical-accent)]"
           >
             View presentation guide
@@ -929,14 +919,14 @@ function SearchResultsView({
           </p>
           <div className="flex flex-wrap gap-2">
             <Link
-              href={routeWithQuery("/differentials/presentations", query)}
+              href={differentialRouteWithQuery("/differentials/presentations", query)}
               className="inline-flex min-h-tap items-center gap-1.5 rounded-lg border border-[color:var(--clinical-accent-border)] bg-[color:var(--clinical-accent-soft)] px-3 text-sm font-extrabold text-[color:var(--clinical-accent)]"
             >
               Browse presentations
               <ChevronRight className="h-4 w-4" aria-hidden />
             </Link>
             <Link
-              href={routeWithQuery("/differentials/diagnoses", query)}
+              href={differentialRouteWithQuery("/differentials/diagnoses", query)}
               className="inline-flex min-h-tap items-center gap-1.5 rounded-lg border border-[color:var(--clinical-accent-border)] bg-[color:var(--clinical-accent-soft)] px-3 text-sm font-extrabold text-[color:var(--clinical-accent)]"
             >
               Browse diagnoses
@@ -1097,7 +1087,7 @@ function SearchResultsView({
             </div>
 
             <Link
-              href={routeWithQuery("/differentials/diagnoses", query)}
+              href={differentialRouteWithQuery("/differentials/diagnoses", query)}
               className="hidden min-h-11 w-full items-center justify-center gap-2 rounded-lg border border-[color:var(--border)] bg-[color:var(--surface)] px-4 text-sm font-extrabold text-[color:var(--clinical-accent)] shadow-[var(--shadow-inset)] transition hover:border-[color:var(--clinical-accent-border)] lg:inline-flex"
             >
               View all catalogue matches ({results.length})
@@ -1106,7 +1096,7 @@ function SearchResultsView({
 
             {selectedCount > 0 ? (
               <Link
-                href={routeWithQuery("/differentials/presentations", query, comparisonIds)}
+                href={differentialSelectedCompareHref(query, comparisonIds)}
                 className="hidden min-h-14 w-full items-center justify-center gap-3 rounded-lg bg-[color:var(--clinical-accent)] px-4 text-base font-extrabold text-[color:var(--clinical-accent-contrast)] shadow-[var(--shadow-elevated)] transition hover:bg-[color:var(--clinical-accent-hover)] lg:inline-flex"
               >
                 <GitCompareArrows className="h-5 w-5" aria-hidden />
@@ -1205,12 +1195,12 @@ export function DifferentialsHome({
   function handleAction(action: DifferentialAction) {
     if (action.target === "presentations") {
       if (onOpenPresentations) onOpenPresentations(action.query);
-      else router.push(routeWithQuery("/differentials/presentations", action.query));
+      else router.push(differentialRouteWithQuery("/differentials/presentations", action.query));
       return;
     }
     if (action.target === "diagnoses") {
       if (onOpenDiagnoses) onOpenDiagnoses(action.query);
-      else router.push(routeWithQuery("/differentials/diagnoses", action.query));
+      else router.push(differentialRouteWithQuery("/differentials/diagnoses", action.query));
       return;
     }
     runSearch(action.query);

src/lib/differentials-navigation.ts

@@ -0,0 +1,24 @@
+/**
+ * Client-safe differentials href helpers.
+ * Keep this module free of `@/lib/differentials` / snapshot imports so the
+ * clinical-dashboard client bundle stays fixture-free.
+ */
+
+export function differentialRouteWithQuery(path: string, query: string, selectedIds?: Iterable<string>) {
+  const params = new URLSearchParams();
+  const trimmedQuery = query.trim();
+  if (trimmedQuery) params.set("q", trimmedQuery);
+  const ids = selectedIds ? Array.from(selectedIds, (id) => id.trim()).filter(Boolean) : [];
+  if (ids.length > 0) params.set("ids", ids.join(","));
+  const suffix = params.toString();
+  return suffix ? `${path}?${suffix}` : path;
+}
+
+/**
+ * Compare-selected CTA href. Resolves the presentation workflow on the server
+ * via `/differentials/presentations` (see presentations/route.ts) so the client
+ * never loads the differentials snapshot just to build a link.
+ */
+export function differentialSelectedCompareHref(query: string, selectedIds: Iterable<string>) {
+  return differentialRouteWithQuery("/differentials/presentations", query, selectedIds);
+}

tests/audit-navigation-auth-regressions.test.ts

@@ -40,7 +40,7 @@ describe("audit navigation and auth regressions", () => {
     );
     expect(presentations.status).toBe(307);
     expect(presentations.headers.get("location")).toBe(
-      "https://clinical-kb.test/differentials/presentations/acute-confusion-encephalopathy?q=acute+confusion&ids=delirium",
+      "/differentials/presentations/acute-confusion-encephalopathy?q=acute+confusion&ids=delirium",
     );
 
     const medications = redirectMedications(new NextRequest("https://clinical-kb.test/medications?ignored=1"));

tests/differentials-navigation.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, it } from "vitest";
+import { NextRequest } from "next/server";
+
+import { GET as redirectPresentations } from "@/app/differentials/presentations/route";
+import { differentialRouteWithQuery, differentialSelectedCompareHref } from "@/lib/differentials-navigation";
+
+describe("differentials navigation", () => {
+  it("builds same-origin relative query routes", () => {
+    expect(differentialRouteWithQuery("/differentials/diagnoses", " acute confusion ")).toBe(
+      "/differentials/diagnoses?q=acute+confusion",
+    );
+  });
+
+  it("keeps compare-selected hrefs client-safe and ID-preserving without resolving the workflow locally", () => {
+    const href = differentialSelectedCompareHref(
+      "Pain",
+      new Set(["anorexia-nervosa", "bulimia-nervosa-binge-purge-pattern"]),
+    );
+
+    expect(href).toBe("/differentials/presentations?q=Pain&ids=anorexia-nervosa%2Cbulimia-nervosa-binge-purge-pattern");
+    expect(href).not.toContain("0.0.0.0");
+    expect(href).not.toMatch(/^https?:\/\//);
+  });
+
+  it("does not import the differentials snapshot module from the client-safe navigation helpers", async () => {
+    const { readFileSync } = await import("node:fs");
+    const source = readFileSync(new URL("../src/lib/differentials-navigation.ts", import.meta.url), "utf8");
+    expect(source).not.toMatch(/from\s+["']@\/lib\/differentials["']/);
+    expect(source).not.toMatch(/differentials-snapshot|loadDifferentialSnapshot/);
+  });
+
+  it("redirects compare selection with a relative Location even when the request host is a bind address", () => {
+    const response = redirectPresentations(
+      new NextRequest(
+        "http://0.0.0.0:4461/differentials/presentations?q=Pain&ids=anorexia-nervosa,bulimia-nervosa-binge-purge-pattern",
+      ),
+    );
+
+    expect(response.status).toBe(307);
+    const location = response.headers.get("location");
+    expect(location).toMatch(/^\/differentials\/presentations\/[^/?]+/);
+    expect(location).toContain("q=Pain");
+    expect(location).not.toContain("0.0.0.0");
+
+    const parsedUrl = new URL(location!, "http://placeholder.invalid");
+    const idsParam = parsedUrl.searchParams.get("ids");
+    expect(idsParam).toBeTruthy();
+    const parsedIds = idsParam!.split(",");
+    expect(parsedIds).toEqual(["anorexia-nervosa", "bulimia-nervosa-binge-purge-pattern"]);
+  });
+});