diff --git a/tools/ci/chunk_dl.py b/tools/ci/chunk_dl.py
index 9b83c54c..79d6e11d 100644
--- a/tools/ci/chunk_dl.py
+++ b/tools/ci/chunk_dl.py
@@ -19,7 +19,9 @@ MIRRORS = ["", "https://gh-proxy.net/", "https://gh-proxy.com/"]
 
 
 def pick_mirror(url: str):
-    """HEAD 探测取 Content-Length；返回（实际可用 URL, 字节数）或 (None, 0)。"""
+    """HEAD 探测取 Content-Length ＋ 前 4 字节 zip 魔数校验（镜像站会回 200 错误页体，
+    只看 Content-Length 会把 195 字节的假体当真——2026-11-03 gh-proxy.net 实证）。
+    返回（实际可用 URL, 字节数）或 (None, 0)。非 zip 目标禁用本件。"""
     for m in MIRRORS:
         u = m + url
         r = subprocess.run(["curl", "-sIL", "-m", "30", u], capture_output=True, text=True)
@@ -30,8 +32,14 @@ def pick_mirror(url: str):
                     size = int(line.split(":", 1)[1].strip())
                 except ValueError:
                     size = 0
-        if size > 0:
-            return u, size
+        if size <= 65536:
+            continue
+        head = subprocess.run(
+            ["curl", "-sL", "-m", "20", "-r", "0-3", "-o", "-", u],
+            capture_output=True)
+        if head.stdout[:2] != b"PK":
+            continue
+        return u, size
     return None, 0
 
 
diff --git a/tools/ci/mac_setup.sh b/tools/ci/mac_setup.sh
index d479eaf2..802361bf 100644
--- a/tools/ci/mac_setup.sh
+++ b/tools/ci/mac_setup.sh
@@ -116,12 +116,17 @@ if /usr/local/bin/gdstyle --version >/dev/null 2>&1; then
 	log "gdstyle 已在位，跳过"
 else
 	TGZ="$(mktemp "${TMPDIR:-/tmp}/gdstyle_XXXXXX.tar.gz")"
-	_ok=0
-	for m in "${MIRRORS[@]}"; do
-		log "下载 gdstyle v${GDSTYLE_VER} darwin（${m:+经 $m}）"
-		if curl -fL --retry 2 -m 600 -o "$TGZ" "${m}${GDSTYLE_URL}"; then _ok=1; break; fi
-	done
-	[ "$_ok" = 1 ] || die "gdstyle 下载失败——手动下载 ${GDSTYLE_URL} 解压放 /usr/local/bin/gdstyle 后重跑"
+	SRC_TGZ="/Users/${INVOKER}/godot-linux/gdstyle-x86_64-apple-darwin.tar.gz"
+	if [ -s "$SRC_TGZ" ] && tar -tzf "$SRC_TGZ" >/dev/null 2>&1; then
+		TGZ="$SRC_TGZ"; log "复用已下载 gdstyle 包: $TGZ"
+	else
+		_ok=0
+		for m in "${MIRRORS[@]}"; do
+			log "下载 gdstyle v${GDSTYLE_VER} darwin（${m:+经 $m}）"
+			if curl -fL --retry 2 -m 600 -o "$TGZ" "${m}${GDSTYLE_URL}" && tar -tzf "$TGZ" >/dev/null 2>&1; then _ok=1; break; fi
+		done
+		[ "$_ok" = 1 ] || die "gdstyle 下载失败——手动下载 ${GDSTYLE_URL} 解压放 /usr/local/bin/gdstyle 后重跑"
+	fi
 	TMPD="$(mktemp -d)"
 	tar -xzf "$TGZ" -C "$TMPD"
 	BIN="$(find "$TMPD" -type f -name 'gdstyle*' | head -1)"