bdf9cupe3: Add expert text search and category browse to the left column

src/components/App.tsx

@@ -7,6 +7,7 @@ import { SignInForm } from "./SignInForm";
 import { Logo } from "./Logo";
 import { Feed } from "./Feed";
 import { DiscoverRails } from "./DiscoverRails";
+import { ExpertSearch } from "./ExpertSearch";
 
 type State = { kind: "loading" } | { kind: "out" } | { kind: "in"; person: Person };
 
@@ -53,6 +54,7 @@ export function App() {
           <ul>
             <li><Link href="/" aria-current="page">Feed</Link></li>
           </ul>
+          <ExpertSearch />
         </nav>
         <div className="col-center">
           <Feed feedUserId={state.person.feedUserId} onSignedOut={() => setState({ kind: "out" })} />

src/components/ExpertSearch.tsx

@@ -0,0 +1,136 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import type { DiscoverCategory } from "@/lib/discover";
+import { fetchDiscover } from "@/lib/discover-client";
+import type { ExpertResult } from "@/lib/experts-search";
+import { fetchExperts } from "@/lib/experts-search-client";
+import { initials } from "@/lib/feed-model";
+
+export type SearchStatus = "idle" | "loading" | "ready" | "error";
+
+export interface ExpertSearchViewProps {
+  query: string;
+  onQuery: (q: string) => void;
+  categories: DiscoverCategory[];
+  activeCategory: string | null;
+  onCategory: (name: string | null) => void;
+  status: SearchStatus;
+  results: ExpertResult[];
+  defaultOpen?: boolean;
+}
+
+export function ExpertSearchView(p: ExpertSearchViewProps) {
+  return (
+    <details className="expert-search" open={p.defaultOpen}>
+      <summary>Find experts</summary>
+      <form role="search" onSubmit={(e) => e.preventDefault()}>
+        <label htmlFor="expert-q">Search experts</label>
+        <input
+          id="expert-q"
+          type="search"
+          value={p.query}
+          placeholder="Name or topic"
+          autoComplete="off"
+          maxLength={80}
+          onChange={(e) => p.onQuery(e.target.value)}
+        />
+      </form>
+      {p.categories.length > 0 ? (
+        <div role="group" aria-label="Browse experts by category" className="chips">
+          {p.categories.map((c) => (
+            <button
+              key={String(c.id)}
+              type="button"
+              className="chip"
+              aria-pressed={p.activeCategory === c.name}
+              onClick={() => p.onCategory(p.activeCategory === c.name ? null : c.name)}
+            >
+              {c.name}
+            </button>
+          ))}
+        </div>
+      ) : null}
+      <div aria-live="polite" className="search-results">
+        {p.status === "loading" ? <p className="search-note">Searching...</p> : null}
+        {p.status === "error" ? <p className="search-note" role="alert">Search is unavailable. Try again.</p> : null}
+        {p.status === "ready" && p.results.length === 0 ? (
+          <p className="search-note">No experts found.</p>
+        ) : null}
+        {p.status === "ready" && p.results.length > 0 ? (
+          <ul className="rail-list">
+            {p.results.map((e) => (
+              <li key={String(e.id)} className="rail-card expert-card" data-testid="search-result">
+                {e.pictureUrl ? (
+                  // eslint-disable-next-line @next/next/no-img-element
+                  <img className="avatar" src={e.pictureUrl} alt="" width={40} height={40} />
+                ) : (
+                  <span className="avatar avatar-initials" aria-hidden="true">{initials(e.displayName)}</span>
+                )}
+                <div className="rail-text">
+                  <strong className="rail-name">{e.displayName || "Expert"}</strong>
+                  {e.byline ? <span className="rail-byline">{e.byline}</span> : null}
+                  {e.rating !== null ? <span className="rail-meta">★ {e.rating.toFixed(1)}</span> : null}
+                </div>
+              </li>
+            ))}
+          </ul>
+        ) : null}
+      </div>
+    </details>
+  );
+}
+
+const DEBOUNCE_MS = 300;
+
+export function ExpertSearch() {
+  const [query, setQuery] = useState("");
+  const [category, setCategory] = useState<string | null>(null);
+  const [categories, setCategories] = useState<DiscoverCategory[]>([]);
+  const [status, setStatus] = useState<SearchStatus>("idle");
+  const [results, setResults] = useState<ExpertResult[]>([]);
+  const [open, setOpen] = useState(true);
+  const seq = useRef(0);
+
+  useEffect(() => {
+    setOpen(window.matchMedia("(min-width: 960px)").matches);
+    let live = true;
+    fetchDiscover().then(
+      (d) => { if (live) setCategories(d.categories); },
+      () => {},
+    );
+    return () => { live = false; };
+  }, []);
+
+  useEffect(() => {
+    const q = query.trim();
+    const mine = ++seq.current;
+    if (!q && !category) {
+      setStatus("idle");
+      setResults([]);
+      return;
+    }
+    setStatus("loading");
+    const t = setTimeout(() => {
+      fetchExperts(q ? { q } : { category: category ?? undefined }).then(
+        (r) => { if (seq.current === mine) { setResults(r); setStatus("ready"); } },
+        () => { if (seq.current === mine) { setResults([]); setStatus("error"); } },
+      );
+    }, q ? DEBOUNCE_MS : 0);
+    return () => clearTimeout(t);
+  }, [query, category]);
+
+  return (
+    <ExpertSearchView
+      key={open ? "open" : "closed"}
+      defaultOpen={open}
+      query={query}
+      onQuery={setQuery}
+      categories={categories}
+      activeCategory={category}
+      onCategory={setCategory}
+      status={status}
+      results={results}
+    />
+  );
+}