feat: ship minecraft theme updates and platform workflow improvements

frontend/src/app/api/image-cache/route.ts

@@ -8,6 +8,16 @@ export const runtime = "nodejs";
 
 const CACHE_DIR = process.env.CSP_IMAGE_CACHE_DIR ?? "/tmp/csp-image-cache";
 const MAX_BYTES = 5 * 1024 * 1024;
+const IMAGE_EXT_TO_TYPE: Record<string, string> = {
+  ".png": "image/png",
+  ".jpg": "image/jpeg",
+  ".jpeg": "image/jpeg",
+  ".webp": "image/webp",
+  ".gif": "image/gif",
+  ".svg": "image/svg+xml",
+  ".bmp": "image/bmp",
+  ".ico": "image/x-icon",
+};
 
 function toArrayBuffer(view: Uint8Array): ArrayBuffer {
   return view.buffer.slice(
@@ -28,6 +38,25 @@ function pickExt(urlObj: URL, contentType: string): string {
   return ".img";
 }
 
+function inferImageType(urlObj: URL, contentType: string): string {
+  const raw = contentType.split(";")[0].trim().toLowerCase();
+  if (raw.startsWith("image/")) return raw;
+  const ext = path.extname(urlObj.pathname || "").toLowerCase();
+  return IMAGE_EXT_TO_TYPE[ext] ?? raw;
+}
+
+function looksLikeImage(urlObj: URL, contentType: string): boolean {
+  if (contentType.startsWith("image/")) return true;
+  const ext = path.extname(urlObj.pathname || "").toLowerCase();
+  return Boolean(IMAGE_EXT_TO_TYPE[ext]);
+}
+
+function redirectToTarget(target: URL): NextResponse {
+  const res = NextResponse.redirect(target.toString(), 307);
+  res.headers.set("Cache-Control", "no-store");
+  return res;
+}
+
 async function readCachedByKey(
   key: string
 ): Promise<{ data: Uint8Array; contentType: string } | null> {
@@ -94,14 +123,12 @@ export async function GET(req: NextRequest) {
     });
 
     if (!resp.ok) {
-      return NextResponse.json(
-        { ok: false, error: `fetch image failed: HTTP ${resp.status}` },
-        { status: 502 }
-      );
+      return redirectToTarget(target);
     }
 
-    const contentType = (resp.headers.get("content-type") ?? "").toLowerCase();
-    if (!contentType.startsWith("image/")) {
+    const headerType = (resp.headers.get("content-type") ?? "").toLowerCase();
+    const contentType = inferImageType(target, headerType);
+    if (!looksLikeImage(target, contentType)) {
       return NextResponse.json({ ok: false, error: "url is not an image" }, { status: 400 });
     }
 
@@ -125,11 +152,8 @@ export async function GET(req: NextRequest) {
         "Cache-Control": "public, max-age=31536000, immutable",
       },
     });
-  } catch (e: unknown) {
-    return NextResponse.json(
-      { ok: false, error: `fetch image failed: ${String(e)}` },
-      { status: 502 }
-    );
+  } catch {
+    return redirectToTarget(target);
   } finally {
     clearTimeout(timer);
   }

frontend/src/app/backend-logs/page.tsx

@@ -59,6 +59,20 @@ type TriggerMissingResp = {
   max_solutions: number;
 };
 
+type AdminUser = {
+  id: number;
+  username: string;
+  rating: number;
+  created_at: number;
+};
+
+type AdminUsersResp = {
+  items: AdminUser[];
+  total_count: number;
+  page: number;
+  page_size: number;
+};
+
 function fmtTs(v: number | null | undefined): string {
   if (!v) return "-";
   return new Date(v * 1000).toLocaleString();
@@ -81,17 +95,24 @@ export default function BackendLogsPage() {
   const [queuedIds, setQueuedIds] = useState<number[]>([]);
   const [triggerLoading, setTriggerLoading] = useState(false);
   const [triggerMsg, setTriggerMsg] = useState("");
+  const [users, setUsers] = useState<AdminUser[]>([]);
+  const [deleteUserId, setDeleteUserId] = useState<number | null>(null);
+  const [userMsg, setUserMsg] = useState("");
 
   const refresh = async () => {
     if (!isAdmin || !token) return;
     setLoading(true);
     setError("");
     try {
-      const data = await apiFetch<BackendLogsResp>(
-        `/api/v1/backend/logs?limit=${limit}&running_limit=20&queued_limit=100`,
-        {},
-        token
-      );
+      const [data, usersData] = await Promise.all([
+        apiFetch<BackendLogsResp>(
+          `/api/v1/backend/logs?limit=${limit}&running_limit=20&queued_limit=100`,
+          {},
+          token
+        ),
+        apiFetch<AdminUsersResp>("/api/v1/admin/users?page=1&page_size=200", {}, token),
+      ]);
+
       setPendingJobs(data.pending_jobs ?? 0);
       setMissingProblems(data.missing_problems ?? 0);
       setItems(data.items ?? []);
@@ -99,6 +120,7 @@ export default function BackendLogsPage() {
       setQueuedJobs(data.queued_jobs ?? []);
       setRunningIds(data.running_problem_ids ?? []);
       setQueuedIds(data.queued_problem_ids ?? []);
+      setUsers(usersData.items ?? []);
     } catch (e: unknown) {
       setError(String(e));
     } finally {
@@ -185,6 +207,45 @@ export default function BackendLogsPage() {
     }
   };
 
+  const deleteUser = async (user: AdminUser) => {
+    if (!isAdmin || !token) return;
+    if (user.username === "admin") {
+      setError(tx("保留管理员账号不可删除", "Reserved admin account cannot be deleted"));
+      return;
+    }
+    const ok = window.confirm(
+      tx(
+        `确认删除用户 ${user.username}(#${user.id})？该用户提交记录、错题本、草稿、积分记录会被级联删除。`,
+        `Delete user ${user.username}(#${user.id})? Submissions, wrong-book, drafts, and points records will be removed by cascade.`
+      )
+    );
+    if (!ok) return;
+
+    setDeleteUserId(user.id);
+    setError("");
+    setUserMsg("");
+    try {
+      await apiFetch(
+        `/api/v1/admin/users/${user.id}`,
+        {
+          method: "DELETE",
+        },
+        token
+      );
+      setUserMsg(
+        tx(
+          `已删除用户 ${user.username}(#${user.id})`,
+          `Deleted user ${user.username}(#${user.id}).`
+        )
+      );
+      await refresh();
+    } catch (e: unknown) {
+      setError(String(e));
+    } finally {
+      setDeleteUserId(null);
+    }
+  };
+
   useEffect(() => {
     if (!isAdmin || !token) return;
     const timer = setInterval(() => {
@@ -250,12 +311,94 @@ export default function BackendLogsPage() {
 
       {error && <p className="mt-3 text-sm text-red-600">{error}</p>}
       {triggerMsg && <p className="mt-3 text-sm text-emerald-700">{triggerMsg}</p>}
+      {userMsg && <p className="mt-3 text-sm text-emerald-700">{userMsg}</p>}
       <p className="mt-3 text-xs text-zinc-500">
         {tx(
           "系统已自动单线程异步处理待队列任务，无需手工点击；上方按钮仅用于立即手动补全。",
           "System auto-processes queued jobs in single-thread async mode; the button above is only for manual trigger."
         )}
       </p>
+
+      <section className="mt-4 rounded-xl border bg-white p-3">
+        <div className="flex flex-wrap items-center justify-between gap-2">
+          <h2 className="text-sm font-medium">{tx("用户管理（可删除）", "User Management (Delete Supported)")}</h2>
+          <p className="text-xs text-zinc-600">
+            {tx("总用户", "Total users")} {users.length}
+          </p>
+        </div>
+
+        <div className="mt-3 divide-y md:hidden">
+          {users.map((user) => (
+            <article key={user.id} className="space-y-1 py-2 text-xs">
+              <p className="font-medium">
+                #{user.id} · {user.username}
+              </p>
+              <p className="text-zinc-600">
+                Rating {user.rating} · {tx("创建", "Created")} {fmtTs(user.created_at)}
+              </p>
+              <button
+                className="rounded border px-2 py-1 text-xs text-red-700 hover:bg-red-50 disabled:opacity-60"
+                disabled={deleteUserId === user.id || user.username === "admin"}
+                onClick={() => void deleteUser(user)}
+              >
+                {user.username === "admin"
+                  ? tx("保留账号", "Reserved")
+                  : deleteUserId === user.id
+                    ? tx("删除中...", "Deleting...")
+                    : tx("删除用户", "Delete User")}
+              </button>
+            </article>
+          ))}
+          {!loading && users.length === 0 && (
+            <p className="py-4 text-center text-sm text-zinc-500">{tx("暂无用户数据", "No users found")}</p>
+          )}
+        </div>
+
+        <div className="mt-2 hidden overflow-x-auto md:block">
+          <table className="min-w-full text-xs">
+            <thead className="bg-zinc-100 text-left">
+              <tr>
+                <th className="px-2 py-2">ID</th>
+                <th className="px-2 py-2">{tx("用户名", "Username")}</th>
+                <th className="px-2 py-2">Rating</th>
+                <th className="px-2 py-2">{tx("创建时间", "Created At")}</th>
+                <th className="px-2 py-2">{tx("操作", "Action")}</th>
+              </tr>
+            </thead>
+            <tbody>
+              {users.map((user) => (
+                <tr key={user.id} className="border-t">
+                  <td className="px-2 py-2">{user.id}</td>
+                  <td className="px-2 py-2">{user.username}</td>
+                  <td className="px-2 py-2">{user.rating}</td>
+                  <td className="px-2 py-2 text-zinc-600">{fmtTs(user.created_at)}</td>
+                  <td className="px-2 py-2">
+                    <button
+                      className="rounded border px-2 py-1 text-xs text-red-700 hover:bg-red-50 disabled:opacity-60"
+                      disabled={deleteUserId === user.id || user.username === "admin"}
+                      onClick={() => void deleteUser(user)}
+                    >
+                      {user.username === "admin"
+                        ? tx("保留账号", "Reserved")
+                        : deleteUserId === user.id
+                          ? tx("删除中...", "Deleting...")
+                          : tx("删除用户", "Delete User")}
+                    </button>
+                  </td>
+                </tr>
+              ))}
+              {!loading && users.length === 0 && (
+                <tr>
+                  <td className="px-2 py-4 text-center text-zinc-500" colSpan={5}>
+                    {tx("暂无用户数据", "No users found")}
+                  </td>
+                </tr>
+              )}
+            </tbody>
+          </table>
+        </div>
+      </section>
+
       <section className="mt-4 grid gap-3 md:grid-cols-2">
         <article className="rounded-xl border bg-white p-3">
           <h2 className="text-sm font-medium">{tx("正在处理（Running）", "Running Jobs")}</h2>

frontend/src/app/globals.css

@@ -35,6 +35,11 @@ body {
   font-size: 1em;
 }
 
+.solution-code-block {
+  font-size: calc(0.875rem * 0.7) !important;
+  line-height: 1.05rem !important;
+}
+
 .print-only {
   display: none;
 }

frontend/src/app/me/page.tsx

@@ -2,6 +2,7 @@
 
 import { useEffect, useMemo, useState } from "react";
 
+import { PixelAvatar } from "@/components/pixel-avatar";
 import { apiFetch } from "@/lib/api";
 import { readToken } from "@/lib/auth";
 import { useI18nText } from "@/lib/i18n";
@@ -218,10 +219,23 @@ export default function MePage() {
 
       {profile && (
         <section className="mt-4 rounded-xl border bg-white p-4 text-sm">
-          <p>ID: {profile.id}</p>
-          <p>{tx("用户名", "Username")}: {profile.username}</p>
-          <p>Rating: {profile.rating}</p>
-          <p>{tx("创建时间", "Created At")}: {fmtTs(profile.created_at)}</p>
+          <div className="flex flex-wrap items-center gap-4">
+            <PixelAvatar
+              seed={`${profile.username}-${profile.id}`}
+              size={72}
+              className="border-zinc-700"
+              alt={`${profile.username} avatar`}
+            />
+            <div className="space-y-1">
+              <p>ID: {profile.id}</p>
+              <p>{tx("用户名", "Username")}: {profile.username}</p>
+              <p>Rating: {profile.rating}</p>
+              <p>{tx("创建时间", "Created At")}: {fmtTs(profile.created_at)}</p>
+              <p className="text-xs text-zinc-500">
+                {tx("默认像素头像按账号随机生成，可作为主题角色形象。", "Default pixel avatar is randomly generated by account as your theme character.")}
+              </p>
+            </div>
+          </div>
         </section>
       )}
 

frontend/src/app/problems/[id]/page.tsx

@@ -2,7 +2,7 @@
 
 import Link from "next/link";
 import { useParams } from "next/navigation";
-import { useEffect, useMemo, useState } from "react";
+import { useEffect, useMemo, useRef, useState } from "react";
 
 import { CodeEditor } from "@/components/code-editor";
 import { MarkdownRenderer } from "@/components/markdown-renderer";
@@ -100,6 +100,12 @@ function scoreRatio(score: number): number {
   return Math.max(0, Math.min(100, score));
 }
 
+function buildDraftSignature(code: string, stdinText: string): string {
+  const normCode = normalizeCodeText(code);
+  const normStdin = (stdinText ?? "").replace(/\r\n?/g, "\n");
+  return `${normCode}\n__STDIN__\n${normStdin}`;
+}
+
 type ResultTone = {
   title: string;
   icon: string;
@@ -154,7 +160,8 @@ type DraftResp = {
   language: string;
   code: string;
   stdin: string;
-  updated_at: number;
+  updated_at: number | null;
+  exists?: boolean;
 };
 
 type SolutionItem = {
@@ -292,6 +299,14 @@ export default function ProblemDetailPage() {
   const [solutionData, setSolutionData] = useState<SolutionResp | null>(null);
   const [solutionMsg, setSolutionMsg] = useState("");
   const [printAnswerMarkdown, setPrintAnswerMarkdown] = useState("");
+  const draftLatestRef = useRef<{ code: string; stdin: string }>({
+    code: starterCode,
+    stdin: defaultRunInput,
+  });
+  const draftLastSavedSigRef = useRef<string>(
+    buildDraftSignature(starterCode, defaultRunInput)
+  );
+  const draftAutoSavingRef = useRef(false);
 
   const llmProfile = useMemo<LlmProfile | null>(() => {
     if (!problem?.llm_profile_json) return null;
@@ -392,8 +407,14 @@ export default function ProblemDetailPage() {
     setShowSolutions(false);
     setSolutionData(null);
     setSolutionMsg("");
+    draftLatestRef.current = { code: starterCode, stdin: defaultRunInput };
+    draftLastSavedSigRef.current = buildDraftSignature(starterCode, defaultRunInput);
   }, [id]);
 
+  useEffect(() => {
+    draftLatestRef.current = { code, stdin: runInput };
+  }, [code, runInput]);
+
   useEffect(() => {
     const clearPrintCache = () => setPrintAnswerMarkdown("");
     window.addEventListener("afterprint", clearPrintCache);
@@ -477,9 +498,21 @@ export default function ProblemDetailPage() {
       if (!token) return;
       try {
         const draft = await apiFetch<DraftResp>(`/api/v1/problems/${id}/draft`, undefined, token);
-        if (draft.code) setCode(draft.code);
-        if (draft.stdin) setRunInput(draft.stdin);
-        setDraftMsg(tx("已自动加载草稿", "Draft auto-loaded"));
+        const hasDraft = Boolean(draft.exists) || Boolean(draft.code) || Boolean(draft.stdin);
+        let nextCode = draftLatestRef.current.code;
+        let nextStdin = draftLatestRef.current.stdin;
+        if (draft.code) {
+          nextCode = draft.code;
+          setCode(draft.code);
+        }
+        if (typeof draft.stdin === "string" && draft.stdin.length > 0) {
+          nextStdin = draft.stdin;
+          setRunInput(draft.stdin);
+        }
+        draftLastSavedSigRef.current = buildDraftSignature(nextCode, nextStdin);
+        if (hasDraft) {
+          setDraftMsg(tx("已自动加载草稿", "Draft auto-loaded"));
+        }
       } catch {
         // ignore empty draft / unauthorized
       }
@@ -487,6 +520,39 @@ export default function ProblemDetailPage() {
     void loadDraft();
   }, [id, tx]);
 
+  useEffect(() => {
+    if (!Number.isFinite(id) || id <= 0) return;
+    const timer = window.setInterval(() => {
+      const token = readToken();
+      if (!token || draftAutoSavingRef.current) return;
+
+      const payload = draftLatestRef.current;
+      const nextSig = buildDraftSignature(payload.code, payload.stdin);
+      if (nextSig === draftLastSavedSigRef.current) return;
+
+      draftAutoSavingRef.current = true;
+      void apiFetch<{ saved: boolean }>(
+        `/api/v1/problems/${id}/draft`,
+        {
+          method: "PUT",
+          body: JSON.stringify({ language: "cpp", code: payload.code, stdin: payload.stdin }),
+        },
+        token
+      )
+        .then(() => {
+          draftLastSavedSigRef.current = nextSig;
+          setDraftMsg(tx("草稿已自动保存（每60秒）", "Draft auto-saved (every 60s)"));
+        })
+        .catch(() => {
+          // Keep silent to avoid noisy notifications on transient network errors.
+        })
+        .finally(() => {
+          draftAutoSavingRef.current = false;
+        });
+    }, 60000);
+    return () => window.clearInterval(timer);
+  }, [id, tx]);
+
   useEffect(() => {
     if (!problemId) return;
     setRunInput((prev) => (prev.trim().length > 0 ? prev : sampleInput || defaultRunInput));
@@ -555,6 +621,7 @@ export default function ProblemDetailPage() {
         },
         token
       );
+      draftLastSavedSigRef.current = buildDraftSignature(code, runInput);
       setDraftMsg(tx("草稿已保存", "Draft saved"));
     } catch (e: unknown) {
       setError(String(e));
@@ -1084,7 +1151,7 @@ export default function ProblemDetailPage() {
                               {tx("写入并试运行", "Insert & Run")}
                             </button>
                           </div>
-                          <pre className="overflow-x-auto whitespace-pre p-3 text-sm leading-6 text-zinc-100">
+                          <pre className="solution-code-block overflow-x-auto whitespace-pre p-3 text-sm leading-6 text-zinc-100">
                             {normalizeCodeText(item.code_cpp)}
                           </pre>
                         </div>