feat: add LoongArch preview download to the website

The Chinese Linux download card now includes a LoongArch processor option and fixes its package type to DEB. It reads a separate strictly validated OSS preview index, while the formal six-target release index and English GitHub downloads remain unchanged.

The page keeps three symmetric platform cards, disables only the LoongArch selection when its index is unavailable, and labels the package as unverified on real LoongArch hardware.

Release note: 官网 Linux 下载新增龙芯 LoongArch 处理器选项，选择后提供独立 DEB 预览包；正式下载与更新索引保持不变。

sites/app.js

@@ -17,6 +17,8 @@
   const isEnglish = root.lang.toLowerCase().startsWith("en");
   const releaseManifestUrl =
     "https://goodbuddy.oss-cn-beijing.aliyuncs.com/releases/latest.json";
+  const loongArchPreviewManifestUrl =
+    "https://goodbuddy.oss-cn-beijing.aliyuncs.com/releases/loongarch-preview/latest.json";
   const releaseFallbackUrl =
     "https://github.com/mesalogo/goodbuddy/releases/latest";
   const releaseRequestTimeoutMs = 10_000;
@@ -24,6 +26,8 @@
   const downloadCards = [
     ...document.querySelectorAll("[data-download-card]"),
   ];
+  let verifiedRelease;
+  let verifiedLoongArchPreview;
   const interfaceCopy = isEnglish
     ? {
         themeDark: "Switch to dark theme",
@@ -65,8 +69,7 @@
     }
   };
 
-  const readBoundedJson = async (response) => {
-    const maximumBytes = releaseIndexApi?.maximumIndexBytes;
+  const readBoundedJson = async (response, maximumBytes) => {
     if (!Number.isSafeInteger(maximumBytes) || maximumBytes < 1) {
       throw new Error("发布索引大小上限无效");
     }
@@ -111,30 +114,165 @@
     return JSON.parse(new TextDecoder().decode(bytes));
   };
 
-  const setReleaseLink = (link, url, visibleText) => {
+  const setLinkText = (link, visibleText) => {
     const newWindowNotice = link.querySelector(".sr-only");
-    link.href = url;
     link.replaceChildren(document.createTextNode(visibleText));
     if (newWindowNotice) {
       link.append(newWindowNotice);
     }
   };
 
-  const setFallbackDownloads = () => {
+  const setReleaseLink = (link, url, visibleText) => {
+    link.href = url;
+    link.target = "_blank";
+    link.rel = "noreferrer";
+    link.removeAttribute("aria-disabled");
+    link.removeAttribute("tabindex");
+    link.classList.remove("is-disabled");
+    setLinkText(link, visibleText);
+  };
+
+  const getDownloadCardControls = (card) => {
+    const platform = card.dataset.downloadCard;
+    const archSelect = card.querySelector("[data-download-arch]");
+    const formatSelect = card.querySelector("[data-download-format]");
+    const container = card.closest(".download-card");
+    const link = container?.querySelector("[data-release-link]");
+    const meta = container?.querySelector("[data-download-meta]");
+    if (
+      !platform ||
+      !(archSelect instanceof HTMLSelectElement) ||
+      !(formatSelect instanceof HTMLSelectElement) ||
+      !(link instanceof HTMLAnchorElement) ||
+      !(meta instanceof HTMLElement)
+    ) {
+      throw new Error("下载卡片结构无效");
+    }
+    return { platform, archSelect, formatSelect, link, meta };
+  };
+
+  const setDownloadUnavailable = (link, meta) => {
+    link.removeAttribute("href");
+    link.removeAttribute("target");
+    link.removeAttribute("rel");
+    link.setAttribute("aria-disabled", "true");
+    link.tabIndex = -1;
+    link.classList.add("is-disabled");
+    setLinkText(link, "龙芯预览包暂不可用");
+    meta.textContent =
+      "实验预览 · 仅 DEB · 索引尚未发布或校验失败；" +
+      "尚未完成真机验证。";
+  };
+
+  const setLoongArchFormat = (formatSelect, selected) => {
+    for (const option of formatSelect.options) {
+      const unavailable = selected && option.value !== "deb";
+      option.hidden = unavailable;
+      option.disabled = unavailable;
+    }
+    if (selected) {
+      formatSelect.value = "deb";
+    }
+    formatSelect.disabled = selected;
+  };
+
+  const updateDownloadCard = (card) => {
+    const {
+      platform,
+      archSelect,
+      formatSelect,
+      link,
+      meta,
+    } = getDownloadCardControls(card);
+    const loongArchSelected =
+      platform === "linux" && archSelect.value === "loong64";
+    setLoongArchFormat(formatSelect, loongArchSelected);
+
+    if (loongArchSelected) {
+      if (!verifiedLoongArchPreview) {
+        setDownloadUnavailable(link, meta);
+        return;
+      }
+      setReleaseLink(
+        link,
+        verifiedLoongArchPreview.artifact.url,
+        "下载 Linux 龙芯 LoongArch DEB 预览版 →",
+      );
+      meta.textContent =
+        `GoodBuddy ${verifiedLoongArchPreview.goodBuddyVersion} · ` +
+        `${formatFileSize(verifiedLoongArchPreview.artifact.size)} · ` +
+        `实验预览 · 未完成龙芯真机验证 · SHA-256 ` +
+        `${verifiedLoongArchPreview.artifact.sha256.slice(0, 12)}…`;
+      return;
+    }
+
+    if (!verifiedRelease) {
+      setReleaseLink(
+        link,
+        releaseFallbackUrl,
+        `前往 GitHub 下载 ${platformNames[platform] ?? platform} →`,
+      );
+      meta.textContent = "请在 GitHub Release 中选择对应的安装文件。";
+      return;
+    }
+
+    const target =
+      verifiedRelease.targets[`${platform}-${archSelect.value}`];
+    const file = target?.files?.[formatSelect.value];
+    if (!file) {
+      throw new Error("下载选项不在已校验的发布索引中");
+    }
+    const platformName = platformNames[platform] ?? platform;
+    const archName =
+      platform === "macos" && archSelect.value === "arm64"
+        ? "Apple 芯片"
+        : archSelect.value === "arm64"
+          ? "ARM64"
+          : "x64";
+    const formatName = formatNames[formatSelect.value] ?? formatSelect.value;
+    setReleaseLink(
+      link,
+      file.url,
+      `下载 ${platformName} ${archName} ${formatName} →`,
+    );
+    meta.textContent =
+      `GoodBuddy ${verifiedRelease.version} · ` +
+      `${formatFileSize(file.size)} · ` +
+      `${archSelect.options[archSelect.selectedIndex]?.text ?? archSelect.value}`;
+  };
+
+  const updateAllDownloadCards = () => {
     for (const card of downloadCards) {
-      const platform = card.dataset.downloadCard;
-      const link = card.closest(".download-card")?.querySelector("[data-release-link]");
-      const meta = card.closest(".download-card")?.querySelector("[data-download-meta]");
-      if (link instanceof HTMLAnchorElement) {
-        setReleaseLink(
-          link,
-          releaseFallbackUrl,
-          `前往 GitHub 下载 ${platformNames[platform] ?? platform ?? ""} →`,
-        );
-      }
-      if (meta instanceof HTMLElement) {
-        meta.textContent = "请在 GitHub Release 中选择对应的安装文件。";
-      }
+      updateDownloadCard(card);
+    }
+  };
+
+  const setFallbackDownloads = () => {
+    verifiedRelease = undefined;
+    updateAllDownloadCards();
+  };
+
+  const setLoongArchPreviewUnavailable = () => {
+    verifiedLoongArchPreview = undefined;
+    const linuxCard = downloadCards.find(
+      (card) => card.dataset.downloadCard === "linux",
+    );
+    if (linuxCard) {
+      updateDownloadCard(linuxCard);
+    }
+  };
+
+  const configureLoongArchPreview = (payload) => {
+    if (!releaseIndexApi?.validateLoongArchPreviewIndex) {
+      throw new Error("龙芯预览索引校验器不可用");
+    }
+    verifiedLoongArchPreview =
+      releaseIndexApi.validateLoongArchPreviewIndex(payload);
+    const linuxCard = downloadCards.find(
+      (card) => card.dataset.downloadCard === "linux",
+    );
+    if (linuxCard) {
+      updateDownloadCard(linuxCard);
     }
   };
 
@@ -142,71 +280,37 @@
     if (!releaseIndexApi?.validateReleaseIndex) {
       throw new Error("发布索引校验器不可用");
     }
-    const release = releaseIndexApi.validateReleaseIndex(payload);
-
-    const updateCard = (card) => {
-      const platform = card.dataset.downloadCard;
-      const archSelect = card.querySelector("[data-download-arch]");
-      const formatSelect = card.querySelector("[data-download-format]");
-      const link = card.closest(".download-card")?.querySelector("[data-release-link]");
-      const meta = card.closest(".download-card")?.querySelector("[data-download-meta]");
-      if (
-        !platform ||
-        !(archSelect instanceof HTMLSelectElement) ||
-        !(formatSelect instanceof HTMLSelectElement) ||
-        !(link instanceof HTMLAnchorElement) ||
-        !(meta instanceof HTMLElement)
-      ) {
-        throw new Error("下载卡片结构无效");
-      }
-
-      const target = release.targets[`${platform}-${archSelect.value}`];
-      const file = target?.files?.[formatSelect.value];
-      if (!file) {
-        throw new Error("下载选项不在已校验的发布索引中");
-      }
-
-      const platformName = platformNames[platform] ?? platform;
-      const archName =
-        platform === "macos" && archSelect.value === "arm64"
-          ? "Apple 芯片"
-          : archSelect.value === "arm64"
-            ? "ARM64"
-            : "x64";
-      const formatName = formatNames[formatSelect.value] ?? formatSelect.value;
-      setReleaseLink(
-        link,
-        file.url,
-        `下载 ${platformName} ${archName} ${formatName} →`,
-      );
-      meta.textContent =
-        `GoodBuddy ${release.version} · ${formatFileSize(file.size)} · ` +
-        `${archSelect.options[archSelect.selectedIndex]?.text ?? archSelect.value}`;
-    };
+    verifiedRelease = releaseIndexApi.validateReleaseIndex(payload);
+    updateAllDownloadCards();
+  };
 
+  const initializeDownloadCards = () => {
     for (const card of downloadCards) {
-      const selects = card.querySelectorAll("select");
-      for (const select of selects) {
+      for (const select of card.querySelectorAll("select")) {
         select.addEventListener("change", () => {
           try {
-            updateCard(card);
+            updateDownloadCard(card);
           } catch {
             setFallbackDownloads();
           }
         });
       }
-      updateCard(card);
+      updateDownloadCard(card);
     }
   };
 
-  const loadRelease = async () => {
+  const fetchBoundedIndex = async (
+    url,
+    maximumBytes,
+    errorLabel,
+  ) => {
     const controller = new AbortController();
     const timeout = window.setTimeout(
       () => controller.abort(),
       releaseRequestTimeoutMs,
     );
     try {
-      const response = await fetch(releaseManifestUrl, {
+      const response = await fetch(url, {
         cache: "no-store",
         credentials: "omit",
         redirect: "error",
@@ -214,16 +318,42 @@
         signal: controller.signal,
       });
       if (!response.ok) {
-        throw new Error(`发布索引请求失败：${response.status}`);
+        throw new Error(`${errorLabel}请求失败：${response.status}`);
       }
-      configureDownloads(await readBoundedJson(response));
-    } catch {
-      setFallbackDownloads();
+      return await readBoundedJson(response, maximumBytes);
     } finally {
       window.clearTimeout(timeout);
     }
   };
 
+  const loadRelease = async () => {
+    try {
+      configureDownloads(
+        await fetchBoundedIndex(
+          releaseManifestUrl,
+          releaseIndexApi?.maximumIndexBytes,
+          "发布索引",
+        ),
+      );
+    } catch {
+      setFallbackDownloads();
+    }
+  };
+
+  const loadLoongArchPreview = async () => {
+    try {
+      configureLoongArchPreview(
+        await fetchBoundedIndex(
+          loongArchPreviewManifestUrl,
+          releaseIndexApi?.maximumPreviewIndexBytes,
+          "龙芯预览索引",
+        ),
+      );
+    } catch {
+      setLoongArchPreviewUnavailable();
+    }
+  };
+
   const getSavedTheme = () => {
     try {
       const savedTheme = localStorage.getItem("goodbuddy-site-theme");
@@ -311,8 +441,10 @@
 
   applyTheme(getSavedTheme() ?? (systemTheme.matches ? "dark" : "light"));
   setHeaderState();
+  initializeDownloadCards();
   if (!isEnglish) {
     void loadRelease();
+    void loadLoongArchPreview();
   }
 
   themeToggle?.addEventListener("click", () => {