Make admin tags list searchable and paginated

Filter by name, used/unused, show project counts, and purge unused
tags so the page stays manageable at scale.

client/src/pages/admin/AdminCategories.tsx

@@ -1,28 +1,79 @@
-import { useEffect, useState } from "react";
+import { useEffect, useMemo, useState } from "react";
 import { api, type Category, type Tag } from "../../lib/api";
+import { usePageTitle } from "../../lib/pageTitle";
+
+type TagRow = Tag & { _count?: { projects: number }; projectCount?: number };
+
+function tagUsage(t: TagRow): number {
+  return t.projectCount ?? t._count?.projects ?? 0;
+}
+
+const PAGE_SIZE = 25;
 
 export function AdminCategories() {
   const [categories, setCategories] = useState<Category[]>([]);
-  const [tags, setTags] = useState<Tag[]>([]);
+  const [tags, setTags] = useState<TagRow[]>([]);
   const [name, setName] = useState("");
   const [msg, setMsg] = useState<string | null>(null);
+  const [err, setErr] = useState<string | null>(null);
+
+  const [tagQuery, setTagQuery] = useState("");
+  const [tagFilter, setTagFilter] = useState<"all" | "used" | "unused">("all");
+  const [tagPage, setTagPage] = useState(1);
+
+  usePageTitle("Categories & Tags · Admin");
 
   function load() {
     api.adminCategories().then(setCategories);
-    api.adminTags().then(setTags);
+    api.adminTags().then((t) => setTags(t as TagRow[]));
   }
 
   useEffect(() => {
     load();
   }, []);
 
+  // Reset page when filters change
+  useEffect(() => {
+    setTagPage(1);
+  }, [tagQuery, tagFilter]);
+
+  const filteredTags = useMemo(() => {
+    const q = tagQuery.trim().toLowerCase();
+    return tags
+      .filter((t) => {
+        if (q && !t.name.toLowerCase().includes(q) && !t.slug.toLowerCase().includes(q)) {
+          return false;
+        }
+        const n = tagUsage(t);
+        if (tagFilter === "used" && n === 0) return false;
+        if (tagFilter === "unused" && n > 0) return false;
+        return true;
+      })
+      .sort((a, b) => {
+        // Used first by count desc, then name
+        const ua = tagUsage(a);
+        const ub = tagUsage(b);
+        if (ua !== ub) return ub - ua;
+        return a.name.localeCompare(b.name);
+      });
+  }, [tags, tagQuery, tagFilter]);
+
+  const totalPages = Math.max(1, Math.ceil(filteredTags.length / PAGE_SIZE));
+  const page = Math.min(tagPage, totalPages);
+  const pageTags = filteredTags.slice((page - 1) * PAGE_SIZE, page * PAGE_SIZE);
+
   async function addCategory(e: React.FormEvent) {
     e.preventDefault();
     if (!name.trim()) return;
-    await api.createCategory({ name: name.trim() });
-    setName("");
-    setMsg("Category created");
-    load();
+    setErr(null);
+    try {
+      await api.createCategory({ name: name.trim() });
+      setName("");
+      setMsg("Category created");
+      load();
+    } catch (e) {
+      setErr((e as Error).message);
+    }
   }
 
   async function removeCategory(id: string, n: string) {
@@ -34,6 +85,34 @@ export function AdminCategories() {
   async function removeTag(id: string, n: string) {
     if (!confirm(`Delete tag “${n}”?`)) return;
     await api.deleteTag(id);
+    setMsg(`Deleted tag “${n}”`);
+    load();
+  }
+
+  async function purgeUnused() {
+    const unused = tags.filter((t) => tagUsage(t) === 0);
+    if (unused.length === 0) {
+      setMsg("No unused tags");
+      return;
+    }
+    if (
+      !confirm(
+        `Delete ${unused.length} unused tag${unused.length === 1 ? "" : "s"}? This cannot be undone.`
+      )
+    ) {
+      return;
+    }
+    setErr(null);
+    let ok = 0;
+    for (const t of unused) {
+      try {
+        await api.deleteTag(t.id);
+        ok++;
+      } catch {
+        /* continue */
+      }
+    }
+    setMsg(`Deleted ${ok} unused tag${ok === 1 ? "" : "s"}`);
     load();
   }
 
@@ -44,6 +123,7 @@ export function AdminCategories() {
         Categories are fixed taxonomy; tags are free-form labels on projects.
       </p>
       {msg && <div className="admin-msg admin-msg--ok">{msg}</div>}
+      {err && <div className="admin-msg admin-msg--err">{err}</div>}
 
       <form className="admin-page__toolbar" onSubmit={addCategory}>
         <input
@@ -94,35 +174,128 @@ export function AdminCategories() {
         </tbody>
       </table>
 
-      <h2 style={{ fontSize: "1rem", marginTop: "2rem" }}>Tags</h2>
+      <div
+        style={{
+          marginTop: "2.5rem",
+          display: "flex",
+          flexWrap: "wrap",
+          alignItems: "baseline",
+          justifyContent: "space-between",
+          gap: "0.75rem",
+        }}
+      >
+        <h2 style={{ fontSize: "1rem", margin: 0 }}>
+          Tags{" "}
+          <span style={{ color: "var(--text-dim)", fontWeight: 400, fontSize: "0.9rem" }}>
+            ({filteredTags.length}
+            {filteredTags.length !== tags.length ? ` of ${tags.length}` : ""})
+          </span>
+        </h2>
+        <button type="button" className="btn btn--ghost btn--sm" onClick={purgeUnused}>
+          Delete unused tags
+        </button>
+      </div>
+
+      <div className="admin-page__toolbar" style={{ marginTop: "0.75rem" }}>
+        <input
+          type="search"
+          placeholder="Search tags…"
+          value={tagQuery}
+          onChange={(e) => setTagQuery(e.target.value)}
+          aria-label="Search tags"
+          style={{
+            flex: "1 1 200px",
+            minWidth: 160,
+            background: "var(--bg-elevated)",
+            border: "1px solid var(--border)",
+            borderRadius: 8,
+            padding: "0.55rem 0.8rem",
+          }}
+        />
+        <select
+          value={tagFilter}
+          onChange={(e) => setTagFilter(e.target.value as typeof tagFilter)}
+          aria-label="Filter tags by usage"
+          style={{
+            background: "var(--bg-elevated)",
+            border: "1px solid var(--border)",
+            borderRadius: 8,
+            padding: "0.55rem 0.8rem",
+          }}
+        >
+          <option value="all">All tags</option>
+          <option value="used">Used on projects</option>
+          <option value="unused">Unused only</option>
+        </select>
+      </div>
+
       <table className="admin-table">
         <thead>
           <tr>
             <th>Name</th>
             <th>Slug</th>
+            <th>Projects</th>
             <th></th>
           </tr>
         </thead>
         <tbody>
-          {tags.map((t) => (
-            <tr key={t.id}>
-              <td>{t.name}</td>
-              <td>
-                <code>{t.slug}</code>
-              </td>
-              <td>
-                <button
-                  type="button"
-                  className="btn btn--danger btn--sm"
-                  onClick={() => removeTag(t.id, t.name)}
-                >
-                  Delete
-                </button>
+          {pageTags.length === 0 ? (
+            <tr>
+              <td colSpan={4} style={{ color: "var(--text-dim)" }}>
+                No tags match this filter.
               </td>
             </tr>
-          ))}
+          ) : (
+            pageTags.map((t) => (
+              <tr key={t.id}>
+                <td>{t.name}</td>
+                <td>
+                  <code>{t.slug}</code>
+                </td>
+                <td style={{ color: tagUsage(t) ? "var(--text-muted)" : "var(--text-dim)" }}>
+                  {tagUsage(t)}
+                </td>
+                <td>
+                  <button
+                    type="button"
+                    className="btn btn--danger btn--sm"
+                    onClick={() => removeTag(t.id, t.name)}
+                  >
+                    Delete
+                  </button>
+                </td>
+              </tr>
+            ))
+          )}
         </tbody>
       </table>
+
+      {filteredTags.length > PAGE_SIZE && (
+        <div
+          className="admin-page__toolbar"
+          style={{ marginTop: "1rem", justifyContent: "center", gap: "1rem" }}
+        >
+          <button
+            type="button"
+            className="btn btn--ghost btn--sm"
+            disabled={page <= 1}
+            onClick={() => setTagPage((p) => Math.max(1, p - 1))}
+          >
+            Previous
+          </button>
+          <span style={{ color: "var(--text-muted)", fontSize: "0.9rem" }}>
+            Page {page} of {totalPages}
+          </span>
+          <button
+            type="button"
+            className="btn btn--ghost btn--sm"
+            disabled={page >= totalPages}
+            onClick={() => setTagPage((p) => Math.min(totalPages, p + 1))}
+          >
+            Next
+          </button>
+        </div>
+      )}
     </div>
   );
 }