feat: add templates page with list and diff comparison views

Server-first: page.tsx renders list and compare views as server components,
with <details>/<summary> accordions and URL-param navigation. Only the two
template selects require a client component (TemplateCompareSelects). Diff
highlighting uses a subtle cyan underline; layout is 2-col on desktop.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/templates/page.tsx

@@ -0,0 +1,283 @@
+import Link from "next/link";
+import { redirect } from "next/navigation";
+import { auth } from "@/auth";
+import { getTemplates } from "@/lib/server-data";
+import { parseRubric, parseQuestions } from "@/lib/export-utils";
+import { TemplateCompareSelects } from "@/components/TemplateCompareSelects";
+
+interface PageProps {
+  searchParams: Promise<{ mode?: string; left?: string; right?: string; diffs?: string }>;
+}
+
+// ── Types ────────────────────────────────────────────────────────────────────
+
+type TemplateDimension = Awaited<ReturnType<typeof getTemplates>>[number]["dimensions"][number];
+type Template = Awaited<ReturnType<typeof getTemplates>>[number];
+
+// ── Sub-components (server) ───────────────────────────────────────────────────
+
+function DimensionAccordion({ dim, index }: { dim: TemplateDimension; index: number }) {
+  const rubricLabels = parseRubric(dim.rubric);
+  const questions = parseQuestions(dim.suggestedQuestions);
+
+  return (
+    <details className="group border-t border-zinc-200 dark:border-zinc-600 first:border-t-0">
+      <summary className="flex cursor-pointer list-none items-center justify-between px-4 py-2.5 hover:bg-zinc-50 dark:hover:bg-zinc-700/50 transition-colors [&::-webkit-details-marker]:hidden">
+        <div className="flex items-center gap-2 min-w-0">
+          <span className="font-mono text-xs text-zinc-400 tabular-nums w-5 shrink-0">{index + 1}.</span>
+          <span className="text-sm font-medium text-zinc-800 dark:text-zinc-100 truncate">{dim.title}</span>
+        </div>
+        <span className="shrink-0 text-zinc-500 text-sm ml-2 group-open:hidden">+</span>
+        <span className="shrink-0 text-zinc-500 text-sm ml-2 hidden group-open:inline">−</span>
+      </summary>
+
+      <div className="px-4 pb-3 space-y-2 bg-zinc-50/50 dark:bg-zinc-700/20">
+        {questions.length > 0 && (
+          <div className="rounded bg-white dark:bg-zinc-800 border border-zinc-200 dark:border-zinc-600 p-2.5">
+            <p className="mb-1.5 text-xs font-medium text-zinc-500">Questions suggérées</p>
+            <ol className="list-decimal list-inside space-y-1 text-sm text-zinc-700 dark:text-zinc-200">
+              {questions.map((q, i) => (
+                <li key={i}>{q}</li>
+              ))}
+            </ol>
+          </div>
+        )}
+        <div className="rounded bg-white dark:bg-zinc-800 border border-zinc-200 dark:border-zinc-600 p-2.5 font-mono text-xs space-y-0.5">
+          {rubricLabels.map((label, i) => (
+            <div key={i} className="text-zinc-600 dark:text-zinc-300">
+              <span className="text-cyan-600 dark:text-cyan-400">{i + 1}</span> {label}
+            </div>
+          ))}
+        </div>
+      </div>
+    </details>
+  );
+}
+
+function ListView({ templates }: { templates: Template[] }) {
+  if (templates.length === 0) {
+    return (
+      <div className="py-12 text-center font-mono text-sm text-zinc-500">
+        Aucun template disponible.
+      </div>
+    );
+  }
+
+  return (
+    <div className="grid gap-4 grid-cols-1 md:grid-cols-2">
+      {templates.map((t) => (
+        <div
+          key={t.id}
+          className="rounded-lg border border-zinc-200 dark:border-zinc-600 bg-white dark:bg-zinc-800 shadow-sm dark:shadow-none overflow-hidden"
+        >
+          <div className="px-4 py-3 flex items-center justify-between border-b border-zinc-200 dark:border-zinc-600 bg-zinc-50 dark:bg-zinc-700/30">
+            <h2 className="font-medium text-zinc-800 dark:text-zinc-100">{t.name}</h2>
+            <span className="font-mono text-xs text-zinc-500">{t.dimensions.length} dim.</span>
+          </div>
+          <div>
+            {t.dimensions.map((dim, i) => (
+              <DimensionAccordion key={dim.id} dim={dim} index={i} />
+            ))}
+          </div>
+        </div>
+      ))}
+    </div>
+  );
+}
+
+function CompareView({
+  templates,
+  leftId,
+  rightId,
+  onlyDiffs,
+}: {
+  templates: Template[];
+  leftId: string;
+  rightId: string;
+  onlyDiffs: boolean;
+}) {
+  const leftTemplate = templates.find((t) => t.id === leftId);
+  const rightTemplate = templates.find((t) => t.id === rightId);
+
+  // Collect all unique slugs, preserving order
+  const slugOrder = new Map<string, number>();
+  for (const t of [leftTemplate, rightTemplate]) {
+    if (!t) continue;
+    for (const dim of t.dimensions) {
+      if (!slugOrder.has(dim.slug)) slugOrder.set(dim.slug, dim.orderIndex);
+    }
+  }
+  const slugs = Array.from(slugOrder.keys()).sort(
+    (a, b) => (slugOrder.get(a) ?? 0) - (slugOrder.get(b) ?? 0)
+  );
+
+  // Pre-compute diffs
+  const diffsBySlugs = new Map<string, number[]>();
+  let totalDiffDims = 0;
+  for (const slug of slugs) {
+    const l = leftTemplate?.dimensions.find((d) => d.slug === slug);
+    const r = rightTemplate?.dimensions.find((d) => d.slug === slug);
+    const ll = l ? parseRubric(l.rubric) : [];
+    const rl = r ? parseRubric(r.rubric) : [];
+    const diff = [0, 1, 2, 3, 4].filter((i) => ll[i] !== rl[i]);
+    diffsBySlugs.set(slug, diff);
+    if (diff.length > 0) totalDiffDims++;
+  }
+
+  const visibleSlugs = onlyDiffs ? slugs.filter((s) => (diffsBySlugs.get(s)?.length ?? 0) > 0) : slugs;
+
+  const base = `?mode=compare&left=${leftId}&right=${rightId}`;
+  const diffsHref = onlyDiffs ? base : `${base}&diffs=1`;
+
+  return (
+    <div>
+      {templates.length > 2 && (
+        <TemplateCompareSelects
+          templates={templates.map((t) => ({ id: t.id, name: t.name }))}
+          leftId={leftId}
+          rightId={rightId}
+          onlyDiffs={onlyDiffs}
+        />
+      )}
+
+      {/* Summary + filter */}
+      <div className="mb-4 flex flex-wrap items-center justify-between gap-3">
+        <p className="font-mono text-xs text-zinc-500">
+          <span className="font-semibold text-amber-600 dark:text-amber-400">{totalDiffDims}</span>
+          {" / "}
+          {slugs.length} dimensions modifiées
+        </p>
+        <Link
+          href={diffsHref}
+          className={`rounded border px-2.5 py-1 font-mono text-xs transition-colors ${
+            onlyDiffs
+              ? "border-amber-400 bg-amber-50 dark:bg-amber-900/20 text-amber-600 dark:text-amber-400"
+              : "border-zinc-300 dark:border-zinc-600 text-zinc-500 dark:text-zinc-400 hover:border-zinc-400"
+          }`}
+        >
+          △ uniquement les différences
+        </Link>
+      </div>
+
+      {/* Column headers */}
+      <div className="grid grid-cols-2 gap-px mb-1">
+        <div className="rounded-t-lg bg-zinc-100 dark:bg-zinc-700/60 px-4 py-2 font-mono text-xs font-semibold text-zinc-600 dark:text-zinc-300">
+          {leftTemplate?.name ?? "—"}
+        </div>
+        <div className="rounded-t-lg bg-zinc-100 dark:bg-zinc-700/60 px-4 py-2 font-mono text-xs font-semibold text-zinc-600 dark:text-zinc-300">
+          {rightTemplate?.name ?? "—"}
+        </div>
+      </div>
+
+      <div className="space-y-2">
+        {visibleSlugs.map((slug, idx) => {
+          const leftDim = leftTemplate?.dimensions.find((d) => d.slug === slug);
+          const rightDim = rightTemplate?.dimensions.find((d) => d.slug === slug);
+          const leftLabels = leftDim ? parseRubric(leftDim.rubric) : [];
+          const rightLabels = rightDim ? parseRubric(rightDim.rubric) : [];
+          const title = (leftDim ?? rightDim)?.title ?? slug;
+          const diffLevels = diffsBySlugs.get(slug) ?? [];
+          const hasDiff = diffLevels.length > 0;
+
+          return (
+            <div
+              key={slug}
+              className="rounded-lg border border-zinc-200 dark:border-zinc-600 overflow-hidden"
+            >
+              <div className="px-4 py-2 border-b border-zinc-200 dark:border-zinc-600 bg-zinc-50 dark:bg-zinc-700/50 flex items-center justify-between gap-2">
+                <span className="font-medium text-sm text-zinc-800 dark:text-zinc-100">
+                  <span className="font-mono text-xs text-zinc-400 mr-1.5 tabular-nums">{idx + 1}.</span>
+                  {title}
+                </span>
+                {hasDiff && (
+                  <span className="shrink-0 font-mono text-xs px-1.5 py-0.5 rounded bg-zinc-200 dark:bg-zinc-600 text-zinc-500 dark:text-zinc-400">
+                    {diffLevels.length} Δ
+                  </span>
+                )}
+              </div>
+              <div className="grid grid-cols-2 divide-x divide-zinc-200 dark:divide-zinc-600">
+                {[
+                  { dim: leftDim, labels: leftLabels },
+                  { dim: rightDim, labels: rightLabels },
+                ].map(({ dim, labels }, col) => (
+                  <div key={col} className="p-3 font-mono text-xs space-y-1">
+                    {dim ? (
+                      labels.map((label, i) => {
+                        const differs = diffLevels.includes(i);
+                        return (
+                          <div key={i} className="flex gap-2 px-1.5 py-1">
+                            <span className="shrink-0 font-bold tabular-nums text-cyan-600 dark:text-cyan-400">
+                              {i + 1}
+                            </span>
+                            <span className={`text-zinc-600 dark:text-zinc-300 ${differs ? "bg-cyan-100/70 dark:bg-cyan-900/30 rounded px-0.5" : ""}`}>
+                              {label}
+                            </span>
+                          </div>
+                        );
+                      })
+                    ) : (
+                      <span className="text-zinc-400 italic">absent</span>
+                    )}
+                  </div>
+                ))}
+              </div>
+            </div>
+          );
+        })}
+      </div>
+    </div>
+  );
+}
+
+// ── Page ─────────────────────────────────────────────────────────────────────
+
+export default async function TemplatesPage({ searchParams }: PageProps) {
+  const session = await auth();
+  if (!session?.user) redirect("/auth/login");
+
+  const { mode, left, right, diffs } = await searchParams;
+  const templates = await getTemplates();
+
+  const isCompare = mode === "compare";
+  const leftId = left ?? templates[0]?.id ?? "";
+  const rightId = right ?? templates[1]?.id ?? templates[0]?.id ?? "";
+  const onlyDiffs = diffs === "1";
+
+  const compareHref = `?mode=compare&left=${leftId}&right=${rightId}`;
+
+  return (
+    <div>
+      <div className="mb-6 flex flex-wrap items-center justify-between gap-3">
+        <h1 className="font-mono text-lg font-medium text-zinc-800 dark:text-zinc-100">Templates</h1>
+        <div className="inline-flex rounded border border-zinc-200 dark:border-zinc-600 bg-zinc-50 dark:bg-zinc-800/50 p-0.5">
+          <Link
+            href="?mode=list"
+            className={`rounded px-2.5 py-1 font-mono text-xs transition-colors ${
+              !isCompare
+                ? "bg-white dark:bg-zinc-700 text-zinc-800 dark:text-zinc-100 shadow-sm"
+                : "text-zinc-500 dark:text-zinc-400 hover:text-zinc-700 dark:hover:text-zinc-300"
+            }`}
+          >
+            liste
+          </Link>
+          <Link
+            href={compareHref}
+            className={`rounded px-2.5 py-1 font-mono text-xs transition-colors ${
+              isCompare
+                ? "bg-white dark:bg-zinc-700 text-zinc-800 dark:text-zinc-100 shadow-sm"
+                : "text-zinc-500 dark:text-zinc-400 hover:text-zinc-700 dark:hover:text-zinc-300"
+            }`}
+          >
+            comparer
+          </Link>
+        </div>
+      </div>
+
+      {isCompare ? (
+        <CompareView templates={templates} leftId={leftId} rightId={rightId} onlyDiffs={onlyDiffs} />
+      ) : (
+        <ListView templates={templates} />
+      )}
+    </div>
+  );
+}

src/components/Header.tsx

@@ -28,6 +28,12 @@ export function Header({ session }: { session: Session | null }) {
               >
                 /new
               </Link>
+              <Link
+                href="/templates"
+                className="text-zinc-500 hover:text-cyan-600 dark:text-zinc-400 dark:hover:text-cyan-400 transition-colors"
+              >
+                /templates
+              </Link>
               {session.user.role === "admin" && (
                 <Link
                   href="/admin"

src/components/TemplateCompareSelects.tsx

@@ -0,0 +1,52 @@
+"use client";
+
+import { useRouter } from "next/navigation";
+
+interface TemplateOption {
+  id: string;
+  name: string;
+}
+
+const selectClass =
+  "rounded border border-zinc-300 dark:border-zinc-600 bg-white dark:bg-zinc-800 px-2 py-1 font-mono text-xs text-zinc-800 dark:text-zinc-100 focus:border-cyan-500 focus:outline-none";
+
+export function TemplateCompareSelects({
+  templates,
+  leftId,
+  rightId,
+  onlyDiffs,
+}: {
+  templates: TemplateOption[];
+  leftId: string;
+  rightId: string;
+  onlyDiffs: boolean;
+}) {
+  const router = useRouter();
+
+  const push = (left: string, right: string) => {
+    const params = new URLSearchParams({ mode: "compare", left, right });
+    if (onlyDiffs) params.set("diffs", "1");
+    router.push(`/templates?${params.toString()}`);
+  };
+
+  return (
+    <div className="mb-4 flex flex-wrap items-center gap-4">
+      <div className="flex items-center gap-2">
+        <span className="font-mono text-xs text-zinc-500">Gauche :</span>
+        <select value={leftId} onChange={(e) => push(e.target.value, rightId)} className={selectClass}>
+          {templates.map((t) => (
+            <option key={t.id} value={t.id}>{t.name}</option>
+          ))}
+        </select>
+      </div>
+      <div className="flex items-center gap-2">
+        <span className="font-mono text-xs text-zinc-500">Droite :</span>
+        <select value={rightId} onChange={(e) => push(leftId, e.target.value)} className={selectClass}>
+          {templates.map((t) => (
+            <option key={t.id} value={t.id}>{t.name}</option>
+          ))}
+        </select>
+      </div>
+    </div>
+  );
+}