feat: implement issues #5-#8 — error states, header search, delete/toggle visibility, auth-aware UI

src/app/(main)/compare/[slug]/results-client.tsx

@@ -13,7 +13,7 @@ import { Badge } from "@/components/ui/badge"
 import { Button } from "@/components/ui/button"
 import { Separator } from "@/components/ui/separator"
 import { Skeleton } from "@/components/ui/skeleton"
-import { Share2, ArrowLeft, Loader2, Trophy } from "lucide-react"
+import { Share2, ArrowLeft, Loader2, Trophy, AlertCircle } from "lucide-react"
 import Link from "next/link"
 
 interface ComparisonResultsClientProps {
@@ -32,6 +32,33 @@ export function ComparisonResultsClient({ initialData }: ComparisonResultsClient
 
   const winner = [...data.items].sort((a, b) => b.overallScore - a.overallScore)[0]
 
+  if (data.status === "failed") {
+    return (
+      <div className="max-w-2xl mx-auto p-4 space-y-6">
+        <div className="rounded-lg border border-red-200 bg-red-50 dark:border-red-900 dark:bg-red-950/30 p-6 space-y-4">
+          <div className="flex items-start gap-3">
+            <AlertCircle className="size-6 text-red-600 shrink-0 mt-0.5" />
+            <div className="space-y-2">
+              <h2 className="text-lg font-semibold text-red-800 dark:text-red-200">
+                Comparison Failed
+              </h2>
+              <p className="text-sm text-red-700 dark:text-red-300">
+                This comparison could not be completed. This may be due to a processing error or
+                invalid input.
+              </p>
+            </div>
+          </div>
+          <Link href="/compare">
+            <Button variant="outline" className="gap-2">
+              <ArrowLeft className="size-4" />
+              Try Again
+            </Button>
+          </Link>
+        </div>
+      </div>
+    )
+  }
+
   if (isResearching) {
     return (
       <div className="max-w-4xl mx-auto p-4 space-y-6">

src/app/(main)/compare/page.tsx

@@ -1,23 +1,36 @@
 "use client"
 
-import { useState, useCallback, KeyboardEvent } from "react"
+import { useState, useCallback, useEffect, KeyboardEvent } from "react"
+import { useRouter } from "next/navigation"
 import { Button } from "@/components/ui/button"
 import { Input } from "@/components/ui/input"
 import { Label } from "@/components/ui/label"
 import { Badge } from "@/components/ui/badge"
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card"
 import { useComparisonStream } from "@/hooks/use-comparison-stream"
-import { X, Plus, Loader2, Sparkles } from "lucide-react"
+import { X, Plus, Loader2, Sparkles, AlertCircle } from "lucide-react"
+import Link from "next/link"
 
 export default function ComparePage() {
   const [query, setQuery] = useState("")
   const [items, setItems] = useState<string[]>([])
   const [itemInput, setItemInput] = useState("")
   const [dimensionHints, setDimensionHints] = useState("")
-  const { progress, startResearch, cancel } = useComparisonStream()
+  const { progress, result, error, comparisonSlug, startResearch, cancel } = useComparisonStream()
+  const router = useRouter()
 
   const isResearching = progress.status === "researching"
 
+  // Auto-navigate to comparison results when stream completes
+  useEffect(() => {
+    if (result && comparisonSlug && !isResearching) {
+      const timer = setTimeout(() => {
+        router.push(`/compare/${comparisonSlug}`)
+      }, 800)
+      return () => clearTimeout(timer)
+    }
+  }, [result, comparisonSlug, isResearching, router])
+
   const addItem = useCallback(() => {
     const trimmed = itemInput.trim()
     if (trimmed && !items.includes(trimmed) && items.length < 10) {
@@ -132,6 +145,28 @@ export default function ComparePage() {
             />
           </div>
 
+          {error && (
+            <div className="rounded-lg border border-red-200 bg-red-50 dark:border-red-900 dark:bg-red-950/30 p-4 space-y-2">
+              <div className="flex items-start gap-2">
+                <AlertCircle className="size-5 text-red-600 shrink-0 mt-0.5" />
+                <div className="space-y-1">
+                  <p className="text-sm font-medium text-red-800 dark:text-red-200">
+                    Something went wrong
+                  </p>
+                  <p className="text-sm text-red-700 dark:text-red-300">{error}</p>
+                  {(error.includes("Authentication") || error.includes("401")) && (
+                    <Link
+                      href="/sign-in"
+                      className="inline-flex items-center text-sm font-medium text-red-700 underline underline-offset-2 hover:text-red-900 dark:text-red-300 dark:hover:text-red-100"
+                    >
+                      Sign in to continue
+                    </Link>
+                  )}
+                </div>
+              </div>
+            </div>
+          )}
+
           {isResearching && (
             <div className="space-y-3 rounded-lg border bg-muted/30 p-4">
               <div className="flex items-center gap-2">

src/app/(main)/explore/page.tsx

@@ -1,6 +1,7 @@
 "use client"
 
 import { useState, useEffect, useCallback } from "react"
+import { useSearchParams } from "next/navigation"
 import { Input } from "@/components/ui/input"
 import { Button } from "@/components/ui/button"
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
@@ -28,13 +29,16 @@ interface ComparisonsResponse {
 }
 
 export default function ExplorePage() {
+  const searchParams = useSearchParams()
+  const initialSearch = searchParams.get("search") ?? ""
+
   const [comparisons, setComparisons] = useState<Comparison[]>([])
   const [total, setTotal] = useState(0)
   const [page, setPage] = useState(1)
   const [loading, setLoading] = useState(false)
   const [error, setError] = useState<string | null>(null)
-  const [searchQuery, setSearchQuery] = useState("")
+  const [searchQuery, setSearchQuery] = useState(initialSearch)
-  const [debouncedSearch, setDebouncedSearch] = useState("")
+  const [debouncedSearch, setDebouncedSearch] = useState(initialSearch)
   const [selectedCategory, setSelectedCategory] = useState("All")
 
   const limit = 20
@@ -71,8 +75,8 @@ export default function ExplorePage() {
   }, [searchQuery, fetchComparisons])
 
   useEffect(() => {
-    fetchComparisons(1, "")
+    fetchComparisons(1, initialSearch)
-  }, [fetchComparisons])
+  }, [fetchComparisons, initialSearch])
 
   const categories = ["All", ...Array.from(new Set(comparisons.flatMap(c => c.tags)))]
 

src/app/(main)/layout.tsx

@@ -1,7 +1,7 @@
 "use client"
 
 import Link from "next/link"
-import { usePathname } from "next/navigation"
+import { usePathname, useRouter } from "next/navigation"
 import { Sparkles, Home, BarChart3, Compass, User, Menu, X, Search } from "lucide-react"
 import { useState } from "react"
 import { Button } from "@/components/ui/button"
@@ -72,6 +72,13 @@ export default function MainLayout({
 }) {
   const [mobileMenuOpen, setMobileMenuOpen] = useState(false)
   const [searchQuery, setSearchQuery] = useState("")
+  const router = useRouter()
+
+  const handleSearchKeyDown = (e: React.KeyboardEvent<HTMLInputElement>) => {
+    if (e.key === "Enter" && searchQuery.trim()) {
+      router.push(`/explore?search=${encodeURIComponent(searchQuery.trim())}`)
+    }
+  }
 
   return (
     <div className="min-h-screen flex flex-col">
@@ -90,6 +97,7 @@ export default function MainLayout({
                 placeholder="Search comparisons..."
                 value={searchQuery}
                 onChange={(e) => setSearchQuery(e.target.value)}
+                onKeyDown={handleSearchKeyDown}
                 className="pl-9 h-9"
               />
             </div>
@@ -146,6 +154,7 @@ export default function MainLayout({
                 placeholder="Search comparisons..."
                 value={searchQuery}
                 onChange={(e) => setSearchQuery(e.target.value)}
+                onKeyDown={handleSearchKeyDown}
                 className="pl-9"
               />
             </div>

src/app/(main)/profile/page.tsx

@@ -6,7 +6,13 @@ import { Button } from "@/components/ui/button"
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
 import { Badge } from "@/components/ui/badge"
 import { Skeleton } from "@/components/ui/skeleton"
-import { BarChart3, Eye, Calendar, Plus, RefreshCw, LogIn } from "lucide-react"
+import {
+  DropdownMenu,
+  DropdownMenuTrigger,
+  DropdownMenuContent,
+  DropdownMenuItem,
+} from "@/components/ui/dropdown-menu"
+import { BarChart3, Eye, Calendar, Plus, RefreshCw, LogIn, MoreVertical, Trash2, Globe, Lock } from "lucide-react"
 import Link from "next/link"
 import { useSession } from "@/lib/auth-client"
 
@@ -91,6 +97,37 @@ export default function ProfilePage() {
     }
   }, [sessionLoading, session, fetchComparisons, fetchStats])
 
+  const handleToggleVisibility = async (comparison: Comparison) => {
+    try {
+      const res = await fetch(`/api/comparisons/${comparison.id}`, {
+        method: "PATCH",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ isPublic: !comparison.isPublic }),
+      })
+      if (res.ok) {
+        fetchComparisons(page)
+        fetchStats()
+      }
+    } catch {
+      // Silently fail — user can retry
+    }
+  }
+
+  const handleDelete = async (comparison: Comparison) => {
+    if (!window.confirm(`Delete "${comparison.title}"? This cannot be undone.`)) return
+    try {
+      const res = await fetch(`/api/comparisons/${comparison.id}`, {
+        method: "DELETE",
+      })
+      if (res.ok) {
+        fetchComparisons(page)
+        fetchStats()
+      }
+    } catch {
+      // Silently fail — user can retry
+    }
+  }
+
   // Not authenticated — show sign-in prompt
   if (!sessionLoading && !session?.user) {
     return (
@@ -207,8 +244,9 @@ export default function ProfilePage() {
         ) : comparisons.length > 0 ? (
           <div className="grid gap-4 sm:grid-cols-2">
             {comparisons.map((comparison) => (
-              <Link key={comparison.id} href={`/compare/${comparison.slug}`}>
+              <Card key={comparison.id} className="h-full group transition-all hover:border-primary hover:shadow-md">
-                <Card className="h-full transition-all hover:border-primary hover:shadow-md">
+                <div className="flex flex-col h-full">
+                  <Link href={`/compare/${comparison.slug}`} className="flex-1">
                     <CardHeader className="pb-3">
                       <CardTitle className="text-base line-clamp-1">{comparison.title}</CardTitle>
                       <CardDescription className="flex items-center gap-2 text-xs">
@@ -233,14 +271,57 @@ export default function ProfilePage() {
                             <Eye className="size-3.5" />
                             {comparison.viewCount.toLocaleString()}
                           </span>
-                        {!comparison.isPublic && (
+                          {!comparison.isPublic ? (
-                          <Badge variant="outline" className="text-xs">Draft</Badge>
+                            <Badge variant="outline" className="text-xs">Private</Badge>
+                          ) : (
+                            <Badge variant="outline" className="text-xs">Public</Badge>
                           )}
                         </div>
                       </div>
                     </CardContent>
-                </Card>
                   </Link>
+                  <div className="flex justify-end px-4 pb-3">
+                    <DropdownMenu>
+                      <DropdownMenuTrigger
+                        className="inline-flex items-center justify-center size-8 rounded-md opacity-0 group-hover:opacity-100 transition-opacity hover:bg-accent"
+                        onClick={(e: React.MouseEvent) => e.stopPropagation()}
+                      >
+                        <MoreVertical className="size-4" />
+                      </DropdownMenuTrigger>
+                      <DropdownMenuContent align="end">
+                        <DropdownMenuItem
+                          onClick={(e) => {
+                            e.stopPropagation()
+                            handleToggleVisibility(comparison)
+                          }}
+                        >
+                          {comparison.isPublic ? (
+                            <>
+                              <Lock className="size-4" />
+                              Make Private
+                            </>
+                          ) : (
+                            <>
+                              <Globe className="size-4" />
+                              Make Public
+                            </>
+                          )}
+                        </DropdownMenuItem>
+                        <DropdownMenuItem
+                          variant="destructive"
+                          onClick={(e) => {
+                            e.stopPropagation()
+                            handleDelete(comparison)
+                          }}
+                        >
+                          <Trash2 className="size-4" />
+                          Delete
+                        </DropdownMenuItem>
+                      </DropdownMenuContent>
+                    </DropdownMenu>
+                  </div>
+                </div>
+              </Card>
             ))}
           </div>
         ) : (

src/app/api/comparisons/[id]/route.ts

@@ -0,0 +1,111 @@
+import { db } from "@/lib/db";
+import { comparisons, sessions, users } from "@/lib/db/schema";
+import { eq, and, gt } from "drizzle-orm";
+import { headers } from "next/headers";
+
+async function getAuthedUserId(): Promise<string | null> {
+  const hdrs = await headers();
+  const cookieHeader = hdrs.get("cookie") ?? "";
+  const cookieMatch = cookieHeader
+    .split(";")
+    .map((c) => c.trim())
+    .find(
+      (c) =>
+        c.startsWith("__Secure-better-auth.session_token=") ||
+        c.startsWith("better-auth.session_token=")
+    );
+  const token = cookieMatch
+    ?.split("=")
+    ?.slice(1)
+    ?.join("=")
+    ?.trim()
+    .split(".")[0];
+  if (!token) return null;
+
+  const sessionRows = await db
+    .select()
+    .from(sessions)
+    .where(and(eq(sessions.token, token), gt(sessions.expiresAt, new Date())))
+    .limit(1);
+  if (!sessionRows.length) return null;
+
+  const userRows = await db
+    .select()
+    .from(users)
+    .where(eq(users.id, sessionRows[0].userId))
+    .limit(1);
+  if (!userRows.length) return null;
+
+  return userRows[0].id;
+}
+
+export async function DELETE(
+  _request: Request,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const userId = await getAuthedUserId();
+  if (!userId) {
+    return Response.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  const { id } = await params;
+
+  const existing = await db
+    .select({ userId: comparisons.userId })
+    .from(comparisons)
+    .where(eq(comparisons.id, id))
+    .limit(1);
+
+  if (!existing.length) {
+    return Response.json({ error: "Not found" }, { status: 404 });
+  }
+
+  if (existing[0].userId !== userId) {
+    return Response.json({ error: "Forbidden" }, { status: 403 });
+  }
+
+  await db.delete(comparisons).where(eq(comparisons.id, id));
+
+  return Response.json({ success: true });
+}
+
+export async function PATCH(
+  request: Request,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const userId = await getAuthedUserId();
+  if (!userId) {
+    return Response.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  const { id } = await params;
+
+  const existing = await db
+    .select({ userId: comparisons.userId, isPublic: comparisons.isPublic })
+    .from(comparisons)
+    .where(eq(comparisons.id, id))
+    .limit(1);
+
+  if (!existing.length) {
+    return Response.json({ error: "Not found" }, { status: 404 });
+  }
+
+  if (existing[0].userId !== userId) {
+    return Response.json({ error: "Forbidden" }, { status: 403 });
+  }
+
+  const body = await request.json();
+  const newIsPublic =
+    typeof body.isPublic === "boolean" ? body.isPublic : !existing[0].isPublic;
+
+  const [updated] = await db
+    .update(comparisons)
+    .set({ isPublic: newIsPublic, updatedAt: new Date() })
+    .where(eq(comparisons.id, id))
+    .returning();
+
+  return Response.json({
+    id: updated.id,
+    isPublic: updated.isPublic,
+  });
+}