diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 591cf6c..fbfdef5 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -31,6 +31,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: installer release fallback tests
+        run: python3 scripts/test-release-fallback.py
+
       # ---------- Rust 存储 ----------
       - name: Rust toolchain
         uses: dtolnay/rust-toolchain@stable
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 64a1f87..0c02614 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -9,7 +9,7 @@
 # 装的人拿到的就是编好的二进制，不需要 GHC / Rust：
 #   curl -fsSL https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.sh \
 #       | sh -s -- --component web
-# 也可下载 ChuRepo 脚本（发行包仍默认取自 GitHub）：
+# 也可下载 ChuRepo 脚本（发行包下载失败时自动回退）：
 #   curl -fsSL https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.sh -o install.sh
 #   sh install.sh --component web
 # 两站发行包与源码安装入口见 docs/install.md。
diff --git a/README.md b/README.md
index e22932f..87b2df8 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,11 @@ ChuSQL 是采用 Haskell SQL 引擎与 Rust 存储层的数据库项目，提供
 Linux / macOS：
 
 ```sh
-curl -fsSL https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.sh | sh -s -- --component web
+(curl -fsSL --connect-timeout 10 \
+  https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.sh -o install.sh ||
+ curl -fsSL --connect-timeout 10 \
+  https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.sh -o install.sh) &&
+sh install.sh --component web
 ```
 
 也可从 ChuRepo 下载后执行：
@@ -35,7 +39,11 @@ sh install.sh --component web
 Windows（PowerShell 里下下来再跑；也有下载 zip 解压的包内安装）：
 
 ```powershell
-irm https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1"
+try {
+    irm https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1" -TimeoutSec 60 -ErrorAction Stop
+} catch {
+    irm https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1" -TimeoutSec 60 -ErrorAction Stop
+}
 & "$env:TEMP\install.ps1" -Component web
 ```
 
@@ -46,7 +54,7 @@ irm https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.ps1 -
 & "$env:TEMP\install.ps1" -Component web
 ```
 
-以上在线安装脚本默认从 GitHub 获取发行包，脚本下载来源不会改变发行包来源。GitHub 不可用时，参见[包内安装](docs/install.md#包内安装)或[从源码安装](docs/install.md#从源码安装)。
+上述命令下载脚本时优先 GitHub，失败后尝试 ChuRepo。脚本安装和更新时也会自动回退：版本查询或发行包下载失败时尝试 ChuRepo；已选定的版本保持不变，校验失败直接报错。两站均无对应发行包时需使用包内安装或源码安装。显式指定其他仓库或归档 URL 时不会回退到官方仓库。
 
 ### 启动
 
diff --git a/docs/install.md b/docs/install.md
index d03cbed..78dba93 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -13,7 +13,11 @@
 Linux / macOS：
 
 ```sh
-curl -fsSL https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.sh | sh -s -- --component web
+(curl -fsSL --connect-timeout 10 \
+  https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.sh -o install.sh ||
+ curl -fsSL --connect-timeout 10 \
+  https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.sh -o install.sh) &&
+sh install.sh --component web
 ```
 
 也可从 ChuRepo 下载后执行：
@@ -28,7 +32,11 @@ sh install.sh --component web
 Windows PowerShell：
 
 ```powershell
-irm https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1"
+try {
+    irm https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1" -TimeoutSec 60 -ErrorAction Stop
+} catch {
+    irm https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1" -TimeoutSec 60 -ErrorAction Stop
+}
 & "$env:TEMP\install.ps1" -Component web
 ```
 
@@ -39,7 +47,7 @@ irm https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.ps1 -
 & "$env:TEMP\install.ps1" -Component web
 ```
 
-以上在线安装脚本默认从 GitHub 获取发行包，脚本下载来源不会改变发行包来源。GitHub 不可用时，参见[包内安装](#包内安装)或[从源码安装](#从源码安装)。
+上述命令下载脚本时优先 GitHub，失败后尝试 ChuRepo。脚本安装和更新时也会自动回退：版本查询或发行包下载失败时尝试 ChuRepo；已选定的版本保持不变，校验失败直接报错。两站均无对应发行包时需使用包内安装或源码安装。显式指定其他仓库或归档 URL 时不会回退到官方仓库。
 
 ## 安装方式
 
diff --git a/scripts/install.ps1 b/scripts/install.ps1
index b20c15a..fc71123 100644
--- a/scripts/install.ps1
+++ b/scripts/install.ps1
@@ -37,6 +37,8 @@ function Note([string]$msg) { Write-Host "  note: $msg" }
 
 # ---- 发行站、平台标签 ----
 $githubBase = if ($env:CHUSQL_GITHUB_BASE) { $env:CHUSQL_GITHUB_BASE.TrimEnd('/') } else { 'https://github.com' }
+$churepoBase = if ($env:CHUSQL_CHUREPO_BASE) { $env:CHUSQL_CHUREPO_BASE.TrimEnd('/') } else { 'https://repo.chunana.cn' }
+$churepoRepo = 'ChuNa7a/ChuSQL'
 $apiBase = if ($githubBase -match '^https?://github\.com$') { 'https://api.github.com' } else { "$githubBase/api/v3" }
 # 查版本走 API，未认证只有 60 次/小时；给了 token 就带上（CI 里 GITHUB_TOKEN 一般就有）
 $githubToken = if ($env:CHUSQL_GITHUB_TOKEN) { $env:CHUSQL_GITHUB_TOKEN } elseif ($env:GITHUB_TOKEN) { $env:GITHUB_TOKEN } else { '' }
@@ -69,18 +71,22 @@ function Select-Tag([bool]$stableOnly, [bool]$needPackage, $releases) {
 
 # 取 URL 的文本内容（字节数组先转字符串）。
 function Get-ResponseText([string]$url) {
-    $response = Invoke-WebRequest -Uri $url -Headers $apiHeaders -UseBasicParsing
+    $headers = if ($url.StartsWith("$churepoBase/")) { @{ 'User-Agent' = 'chusql-install' } } else { $apiHeaders }
+    $response = Invoke-WebRequest -Uri $url -Headers $headers -UseBasicParsing -TimeoutSec 300
     if ($response.Content -is [byte[]]) { return [System.Text.Encoding]::UTF8.GetString($response.Content) }
     return [string]$response.Content
 }
 
 # 拉取 release 列表并逐个输出。
 function Get-Releases {
-    try { $text = Get-ResponseText "$apiBase/repos/$Repo/releases?per_page=100" } catch { return }
-    try { $parsed = ConvertFrom-Json -InputObject $text } catch { return }
-    if ($null -eq $parsed) { return }
-    foreach ($release in @($parsed)) {
-        if ($null -ne $release) { Write-Output $release }
+    $urls = @("$apiBase/repos/$Repo/releases?per_page=100")
+    if ($Repo -eq 'TheBadRoger/ChuSQL') { $urls += "$churepoBase/api/v1/repos/$churepoRepo/releases?limit=100" }
+    foreach ($url in $urls) {
+        try {
+            $parsed = @(ConvertFrom-Json -InputObject (Get-ResponseText $url))
+            $releases = @($parsed | Where-Object { $null -ne $_ -and $_.tag_name })
+            if ($releases.Count -gt 0) { return $releases }
+        } catch { Note "release API unavailable: $url" }
     }
 }
 
@@ -241,13 +247,27 @@ if (-not (Test-Path (Join-Path $pack 'bin\chusql_core_storage.dll'))) {
         $tryUrl = if ($Version -eq 'latest') { "$githubBase/$Repo/releases/latest/download/$candidate" }
         else { "$githubBase/$Repo/releases/download/$Version/$candidate" }
         try {
-            Invoke-WebRequest -Uri $tryUrl -Headers $apiHeaders -OutFile $zip -UseBasicParsing
+            Invoke-WebRequest -Uri $tryUrl -Headers $apiHeaders -OutFile $zip -UseBasicParsing -TimeoutSec 300
             $asset = $candidate
             $assetUrl = $tryUrl
             break
-        } catch {
-            continue
-        }
+        } catch { Note "asset unavailable: $tryUrl" }
+        if ($Repo -ne 'TheBadRoger/ChuSQL') { continue }
+        try {
+            $fallbackVersion = $Version
+            if ($fallbackVersion -eq 'latest') {
+                $latest = ConvertFrom-Json -InputObject (Get-ResponseText "$churepoBase/api/v1/repos/$churepoRepo/releases/latest")
+                $fallbackVersion = $latest.tag_name
+                if (-not $fallbackVersion) { throw 'ChuRepo returned no release tag' }
+            }
+            $tryUrl = "$churepoBase/$churepoRepo/releases/download/$fallbackVersion/$candidate"
+            Note "trying ChuRepo: $candidate ($fallbackVersion)"
+            Invoke-WebRequest -Uri $tryUrl -OutFile $zip -UseBasicParsing -TimeoutSec 300
+            $asset = $candidate
+            $assetUrl = $tryUrl
+            $Version = $fallbackVersion
+            break
+        } catch { Note "ChuRepo asset unavailable: $candidate" }
     }
     if (-not $asset) {
         Fail "no package for windows-$arch in $Repo ($Version); try -ListVersions, or install from an archive you downloaded yourself"
diff --git a/scripts/install.sh b/scripts/install.sh
index e7e3a29..c046af1 100644
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -17,6 +17,9 @@ esac
 
 # 查版本走 API，未认证只有 60 次/小时；给了 token 就带上（CI 里 GITHUB_TOKEN 一般就有）
 github_token="${CHUSQL_GITHUB_TOKEN:-${GITHUB_TOKEN:-}}"
+churepo_base="${CHUSQL_CHUREPO_BASE:-https://repo.chunana.cn}"
+churepo_base="${churepo_base%/}"
+churepo_repo='ChuNa7a/ChuSQL'
 
 # 打印用法、选项与环境变量说明。
 usage() {
@@ -44,7 +47,7 @@ usage: ./install.sh [--component web|cli|both] [options]
   --no-service            skip Linux systemd registration and boot autostart
 
 where the files come from:
-  (default)               a package next to this script, else the newest GitHub release
+  (default)               a local package, else GitHub releases with ChuRepo fallback
   --url URL|PATH          install from this archive (URL, file:// URL or local path)
   --repo OWNER/NAME       GitHub repository (default: TheBadRoger/ChuSQL)
   --version TAG           release tag to download / git ref to build
@@ -59,6 +62,8 @@ environment:
                           --password
   CHUSQL_GITHUB_BASE      GitHub base URL: GitHub Enterprise, a mirror, or a
                           local test fixture (default: https://github.com)
+  CHUSQL_CHUREPO_BASE     fallback base URL (default: https://repo.chunana.cn)
+                          fallback only applies to the default repository
   CHUSQL_GITHUB_TOKEN     token for the version API (or GITHUB_TOKEN); without
                           one the API allows 60 requests per hour
 EOF
@@ -276,15 +281,15 @@ new_tmp() {
 download() {
     if command -v curl >/dev/null 2>&1; then
         if [ -n "${3:-}" ]; then
-            curl -fsSL -H "$3" -H 'Accept: application/vnd.github+json' -o "$2" "$1" || return 1
+            curl -fsSL --connect-timeout 10 --max-time 300 -H "$3" -H 'Accept: application/vnd.github+json' -o "$2" "$1" || return 1
         else
-            curl -fsSL -o "$2" "$1" || return 1
+            curl -fsSL --connect-timeout 10 --max-time 300 -o "$2" "$1" || return 1
         fi
     elif command -v wget >/dev/null 2>&1; then
         if [ -n "${3:-}" ]; then
-            wget -q --header="$3" --header='Accept: application/vnd.github+json' -O "$2" "$1" || return 1
+            wget -q --timeout=30 --tries=1 --header="$3" --header='Accept: application/vnd.github+json' -O "$2" "$1" || return 1
         else
-            wget -q -O "$2" "$1" || return 1
+            wget -q --timeout=30 --tries=1 -O "$2" "$1" || return 1
         fi
     else
         fail 'need curl or wget to download the package'
@@ -342,18 +347,41 @@ detect_platform() {
 }
 
 # ---- 发行 tag：问 GitHub API（不依赖 jq，用 awk 读 JSON）----
-# 请求 GitHub API 并落盘。
+# 请求发行列表，默认仓库失败或无版本时回退。
 api_get() {
     if [ -n "$github_token" ]; then
-        download "$api_base$1" "$2" "Authorization: Bearer $github_token"
+        download "$api_base$1" "$2" "Authorization: Bearer $github_token" &&
+            grep -q '"tag_name"' "$2" && return 0
     else
-        download "$api_base$1" "$2"
+        download "$api_base$1" "$2" && grep -q '"tag_name"' "$2" && return 0
     fi
+    [ "$repo" = "$default_repo" ] || return 1
+    note 'release API unavailable or empty; trying ChuRepo' >&2
+    download "$churepo_base/api/v1/repos/$churepo_repo/releases?limit=100" "$2"
+}
+
+# 将紧凑 JSON 按字符串外的分隔符换行。
+json_lines() {
+    awk '
+        {
+            for (i = 1; i <= length($0); i++) {
+                c = substr($0, i, 1)
+                printf "%s", c
+                if (quoted) {
+                    if (escaped) escaped = 0
+                    else if (c == "\\") escaped = 1
+                    else if (c == "\"") quoted = 0
+                } else if (c == "\"") quoted = 1
+                else if (c ~ /[][{},]/) printf "\n"
+            }
+            printf "\n"
+        }
+    ' "$1"
 }
 
 # 把 release JSON 解析成 tag 与资源行。
 parse_releases() {
-    awk '
+    json_lines "$1" | awk '
         in_assets {
             if ($0 ~ /^[[:space:]]*\]/) { in_assets = 0; next }
             if ($0 ~ /"name":/) {
@@ -372,7 +400,7 @@ parse_releases() {
         }
         /"prerelease":/ { pre = ($0 ~ /true/) ? 1 : 0; next }
         END { if (tag != "") { print tag "\t" pre "\t" assets } }
-    ' "$1"
+    '
 }
 
 # 这份 release 里有没有本平台的包。
@@ -468,6 +496,19 @@ fetch_asset() {
         note "asset      $asset"
         return 0
     fi
+    [ "$repo" = "$default_repo" ] || return 1
+    fallback_version="$version"
+    if [ "$fallback_version" = 'latest' ]; then
+        download "$churepo_base/api/v1/repos/$churepo_repo/releases/latest" "$tmp/latest.json" 2>/dev/null || return 1
+        fallback_version=$(parse_releases "$tmp/latest.json" | cut -f1)
+        [ -n "$fallback_version" ] || return 1
+    fi
+    url="$churepo_base/$churepo_repo/releases/download/$fallback_version/$asset"
+    note "trying ChuRepo: $asset ($fallback_version)"
+    if download "$url" "$archive" 2>/dev/null; then
+        version="$fallback_version"
+        return 0
+    fi
     return 1
 }
 
diff --git a/scripts/test-release-fallback.py b/scripts/test-release-fallback.py
new file mode 100644
index 0000000..d095a5c
--- /dev/null
+++ b/scripts/test-release-fallback.py
@@ -0,0 +1,187 @@
+#!/usr/bin/env python3
+import hashlib
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+import json
+from pathlib import Path
+import re
+import shutil
+import subprocess
+import tempfile
+import threading
+import unittest
+
+# 用本机 HTTP 夹具验证发行源回退、版本固定与令牌隔离。
+
+
+class ReleaseFallback(unittest.TestCase):
+    # 启动只响应测试路由的发行站。
+    def setUp(self):
+        self.routes = {}
+        self.requests = []
+        fixture = self
+
+        class Handler(BaseHTTPRequestHandler):
+            # 按夹具返回响应并记录认证头。
+            def do_GET(self):
+                fixture.requests.append((self.path, self.headers.get("Authorization")))
+                status, body = fixture.routes.get(self.path, (404, b"missing"))
+                self.send_response(status)
+                self.end_headers()
+                self.wfile.write(body)
+
+            # 隐藏 HTTP 访问日志。
+            def log_message(self, *args):
+                pass
+
+        self.server = ThreadingHTTPServer(("127.0.0.1", 0), Handler)
+        self.thread = threading.Thread(target=self.server.serve_forever, daemon=True)
+        self.thread.start()
+        self.base = f"http://127.0.0.1:{self.server.server_port}"
+        self.temp = tempfile.TemporaryDirectory()
+        self.root = Path(self.temp.name)
+        source = (Path(__file__).parent / "install.sh").read_text()
+        self.functions = "\n".join(re.findall(r"^[a-z_]+\(\) \{[^\n]*\}$|^[a-z_]+\(\) \{\n.*?^\}", source, re.M | re.S))
+        self.setup = f"""set -eu
+{self.functions}
+default_repo=TheBadRoger/ChuSQL
+repo=$default_repo
+github_base={self.base}/github
+api_base=$github_base/api/v3
+churepo_base={self.base}/churepo
+churepo_repo=ChuNa7a/ChuSQL
+github_token=secret-test-token
+tmp={self.root}
+version=v-test
+labels=linux-x86_64
+os=linux
+arch=x86_64
+ext=tar.gz
+"""
+
+    # 停止夹具并清理临时文件。
+    def tearDown(self):
+        self.server.shutdown()
+        self.server.server_close()
+        self.thread.join()
+        self.temp.cleanup()
+
+    # 执行真实安装脚本中的发行函数。
+    def shell(self, command):
+        return subprocess.run(["sh", "-c", self.setup + command], capture_output=True, text=True, timeout=15)
+
+    # 验证紧凑 API、附件回退、同站校验与认证隔离。
+    def test_api_and_asset_fallback(self):
+        releases = [{"tag_name": "v-test", "prerelease": False,
+                     "body": 'text with [brackets], \"quotes\"',
+                     "assets": [{"name": "chusql-linux-x86_64.tar.gz"}]}]
+        api = "/churepo/api/v1/repos/ChuNa7a/ChuSQL/releases?limit=100"
+        self.routes[api] = (200, json.dumps(releases).encode())
+        asset = "/churepo/ChuNa7a/ChuSQL/releases/download/v-test/chusql-linux-x86_64.tar.gz"
+        self.routes[asset] = (200, b"release-package")
+        digest = hashlib.sha256(b"release-package").hexdigest()
+        self.routes[asset + ".sha256"] = (200, digest.encode())
+        result = self.shell('version=latest; resolve_version; [ "$version" = v-test ]; fetch_asset chusql-linux-x86_64.tar.gz; verify_checksum "$url" "$archive"')
+        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+        self.assertIn("(ok)", result.stdout)
+        self.assertEqual((self.root / "chusql-linux-x86_64.tar.gz").read_bytes(), b"release-package")
+        self.assertTrue(any(auth for path, auth in self.requests if path.startswith("/github/")))
+        self.assertTrue(all(auth is None for path, auth in self.requests if path.startswith("/churepo/")))
+
+    # 列表不可用时从备用站解析 latest 的具体标签。
+    def test_latest_redirect_fallback(self):
+        self.routes["/churepo/api/v1/repos/ChuNa7a/ChuSQL/releases/latest"] = (
+            200, json.dumps({"tag_name": "v-latest", "assets": []}).encode())
+        asset = "/churepo/ChuNa7a/ChuSQL/releases/download/v-latest/package.tar.gz"
+        self.routes[asset] = (200, b"latest-package")
+        result = self.shell('version=latest; fetch_asset package.tar.gz; [ "$version" = v-latest ]')
+        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+
+    # 两站缺少指定版本时不得静默换版。
+    def test_missing_pinned_version_fails(self):
+        result = self.shell('fetch_asset chusql-linux-x86_64.tar.gz')
+        self.assertNotEqual(result.returncode, 0)
+        self.assertTrue(all("latest" not in path for path, _ in self.requests))
+
+    # 主站可用时无需访问备用站。
+    def test_primary_success(self):
+        path = "/github/TheBadRoger/ChuSQL/releases/download/v-test/package.tar.gz"
+        self.routes[path] = (200, b"primary")
+        result = self.shell('fetch_asset package.tar.gz')
+        self.assertEqual(result.returncode, 0, result.stderr)
+        self.assertEqual(self.requests, [(path, None)])
+
+    # 显式仓库不回退至官方仓库。
+    def test_custom_repo_does_not_fallback(self):
+        result = self.shell('repo=custom/project; fetch_asset package.tar.gz')
+        self.assertNotEqual(result.returncode, 0)
+        self.assertTrue(all(path.startswith("/github/") for path, _ in self.requests))
+
+    # 校验失败须中止，不能当作网络失败。
+    def test_corrupt_checksum_fails(self):
+        path = "/churepo/ChuNa7a/ChuSQL/releases/download/v-test/package.tar.gz"
+        self.routes[path] = (200, b"corrupt")
+        self.routes[path + ".sha256"] = (200, b"0" * 64)
+        result = self.shell('fetch_asset package.tar.gz; verify_checksum "$url" "$archive"')
+        self.assertNotEqual(result.returncode, 0)
+        self.assertIn("checksum mismatch", result.stderr)
+
+    # 执行 PowerShell 的真实版本查询和下载校验代码。
+    def powershell(self, command, download=False):
+        if not shutil.which("pwsh"):
+            self.skipTest("pwsh is required for PowerShell fallback tests")
+        source = (Path(__file__).parent / "install.ps1").resolve()
+        script = f"""$ErrorActionPreference = 'Stop'
+$tokens = $null; $errors = $null
+$ast = [System.Management.Automation.Language.Parser]::ParseFile('{source}', [ref]$tokens, [ref]$errors)
+if ($errors.Count) {{ throw ($errors | Out-String) }}
+$ast.FindAll({{ param($node) $node -is [System.Management.Automation.Language.FunctionDefinitionAst] }}, $true) | ForEach-Object {{ Invoke-Expression $_.Extent.Text }}
+$Repo = 'TheBadRoger/ChuSQL'
+$githubBase = '{self.base}/github'
+$apiBase = \"$githubBase/api/v3\"
+$churepoBase = '{self.base}/churepo'
+$churepoRepo = 'ChuNa7a/ChuSQL'
+$apiHeaders = @{{ Authorization = 'Bearer secret-test-token' }}
+$Version = 'v-test'
+$arch = 'x86_64'
+$labels = @('windows-x86_64')
+$tempDir = '{self.root}'
+"""
+        if download:
+            text = source.read_text()
+            script += text[text.index('    # 一个平台一个包：'):text.index("    Step 'Unpacking the package'")]
+        script += "\n" + command
+        self.root.mkdir(exist_ok=True)
+        path = self.root / "test.ps1"
+        path.write_text(script)
+        return subprocess.run(["pwsh", "-NoProfile", "-File", str(path)], capture_output=True, text=True, timeout=20)
+
+    # Windows 下载回退并校验，备用站不接收主站令牌。
+    def test_powershell_fallback(self):
+        api = "/churepo/api/v1/repos/ChuNa7a/ChuSQL/releases?limit=100"
+        self.routes[api] = (200, json.dumps([{"tag_name": "v-test", "assets": []}]).encode())
+        asset = "/churepo/ChuNa7a/ChuSQL/releases/download/v-test/chusql-windows-x86_64.zip"
+        self.routes[asset] = (200, b"windows-package")
+        digest = hashlib.sha256(b"windows-package").hexdigest()
+        self.routes[asset + ".sha256"] = (200, digest.encode())
+        result = self.powershell('if (@(Get-Releases)[0].tag_name -ne "v-test") { throw "wrong release" }')
+        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+        result = self.powershell('if ($Version -ne "v-test") { throw "version changed" }', download=True)
+        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+        self.assertIn("(ok)", result.stdout)
+        self.assertTrue(all(auth is None for path, auth in self.requests if path.startswith("/churepo/")))
+
+    # Windows 双站缺包与校验错误均须失败。
+    def test_powershell_errors(self):
+        result = self.powershell('', download=True)
+        self.assertNotEqual(result.returncode, 0)
+        self.assertTrue(all("latest" not in path for path, _ in self.requests))
+        asset = "/churepo/ChuNa7a/ChuSQL/releases/download/v-test/chusql-windows-x86_64.zip"
+        self.routes[asset] = (200, b"corrupt")
+        self.routes[asset + ".sha256"] = (200, b"0" * 64)
+        result = self.powershell('', download=True)
+        self.assertNotEqual(result.returncode, 0)
+        self.assertIn("checksum mismatch", result.stdout)
+
+
+if __name__ == "__main__":
+    unittest.main()