fix: correct download error message + fall back to /dists for legacy /packages base

- msg.err.download-failed now reads generic '下载 %s 失败' (was wrongly '下载语言包...'),
  so a failed .pdm download no longer claims it's a language pack. Synced zh/en packs.
- registry lookup (install_from_registry + registry_fetch) now also tries the /dists
  subpath when a mirror base ends with .../mirror/packages, so a stale mirror.ini keeps
  working after the mirror was reformed to dists/+files/.

src/i18n.c

@@ -58,7 +58,7 @@ static const char *kBuiltinZh =
 "\"msg.path-exists\":\"PATH 已包含 PMM 目录\",\"msg.err.registry-not-found\":\"找不到软件包 '%s'\","
 "\"msg.pmm-self-replaced\":\"pmm 已更新到 %s\",\"msg.pmm-self-hint\":\"无法覆盖 %s（需 root/管理员）;新版本在 %s。请将其加入 PATH 并在当前 shell 运行 hash -r\","
 "\"msg.err.usage\":\"用法\",\"msg.err.unknown-cmd\":\"未知命令 '%s' (试试 'pmm help')\","
-"\"msg.err.download-failed\":\"下载语言包 %s 失败\",\"msg.err.invalid-locale\":\"无效语言 %s\","
+"\"msg.err.download-failed\":\"下载 %s 失败\",\"msg.err.invalid-locale\":\"无效语言 %s\","
 "\"msg.err.not-found\":\"找不到软件包 '%s'\",\"msg.err.failed-install\":\"安装 %s 失败\",\"msg.err.conflict\":\"无法安装 %s:与已装的 %s 冲突\","
 "\"msg.err.no-registry-mirror\":\"没有配置注册表镜像\",\"msg.err.cannot-write\":\"无法写入 %s\","
 "\"desc.install\":\"安装\",\"desc.remove\":\"卸载\",\"desc.update\":\"刷新索引\","

src/install.c

@@ -814,16 +814,28 @@ int install_from_registry(const char *name, const char *spec, const char *mirror
     char *body = NULL;
     char *used_base = NULL;
     for (int i = 0; i < nb; i++) {
-        snprintf(url, sizeof(url), "%s/%s.json", bases[i], name);
-        pmm_info("%s", pmm_tr_fmt("msg.looking-up", name, bases[i]));
-        body = http_get(url, &status);
-        if (getenv("PMM_DEBUG")) fprintf(stderr, "[reg] %s -> body=%s status=%d\n",
-                                         bases[i], body ? "set" : "NULL", status);
-        /* accept any body that isn't an explicit not-found/server error; some
-         * curl builds don't emit the status marker the way we expect, so a
-         * non-NULL body with an indeterminate status should still be parsed */
-        if (body && status != 404 && status != 403 && status != 503) { used_base = bases[i]; break; }
-        free(body); body = NULL;
+        char used = 0;
+        /* layout migration: an old .../mirror/packages base also falls back to
+         * .../mirror/dists, so stale mirror.ini keeps working after the reform. */
+        char distsbase[2048];
+        snprintf(distsbase, sizeof(distsbase), "%s", bases[i]);
+        size_t dbl = strlen(distsbase);
+        static const char *pkgsuf = "/packages";
+        size_t dpl = strlen(pkgsuf);
+        int isold = (dbl >= dpl && strcmp(distsbase + dbl - dpl, pkgsuf) == 0);
+        if (isold) snprintf(distsbase + dbl - dpl, sizeof(distsbase) - (dbl - dpl), "/dists");
+
+        for (int attempt = 0; attempt < (isold ? 2 : 1); attempt++) {
+            const char *use = (attempt == 0) ? bases[i] : distsbase;
+            snprintf(url, sizeof(url), "%s/%s.json", use, name);
+            pmm_info("%s", pmm_tr_fmt("msg.looking-up", name, use));
+            body = http_get(url, &status);
+            if (getenv("PMM_DEBUG")) fprintf(stderr, "[reg] %s -> body=%s status=%d\n",
+                                             use, body ? "set" : "NULL", status);
+            if (body && status != 404 && status != 403 && status != 503) { used_base = bases[i]; used = 1; break; }
+            free(body); body = NULL;
+        }
+        if (used) break;
     }
     if (!body) {
         pmm_error("%s", pmm_tr_fmt("msg.err.registry-not-found", name));

src/main.c

@@ -197,10 +197,24 @@ static char *registry_fetch(const char *rel, int *outstatus) {
             bases[nb++] = ml->items[i].registry;
     char url[2048]; int status = 0; char *body = NULL;
     for (int i = 0; i < nb; i++) {
-        snprintf(url, sizeof(url), "%s/%s", bases[i], rel);
-        body = http_get(url, &status);
-        if (body && status != 404 && status != 403 && status != 503) break;
-        free(body); body = NULL;
+        /* layout migration: an old .../mirror/packages base also falls back to
+         * .../mirror/dists, so a stale mirror.ini keeps working after the reform. */
+        char distsbase[2048];
+        snprintf(distsbase, sizeof(distsbase), "%s", bases[i]);
+        size_t dbl = strlen(distsbase);
+        static const char *pkgsuf = "/packages";
+        size_t dpl = strlen(pkgsuf);
+        int isold = (dbl >= dpl && strcmp(distsbase + dbl - dpl, pkgsuf) == 0);
+        if (isold) snprintf(distsbase + dbl - dpl, sizeof(distsbase) - (dbl - dpl), "/dists");
+
+        for (int attempt = 0; attempt < (isold ? 2 : 1); attempt++) {
+            const char *use = (attempt == 0) ? bases[i] : distsbase;
+            snprintf(url, sizeof(url), "%s/%s", use, rel);
+            body = http_get(url, &status);
+            if (body && status != 404 && status != 403 && status != 503) break;
+            free(body); body = NULL;
+        }
+        if (body) break;
     }
     mirrors_free(ml);
     if (outstatus) *outstatus = status;

web/mirror/lang/en-US.pjson

@@ -86,7 +86,7 @@
   "msg.err.cannot-read": "cannot read %s",
   "msg.err.cannot-open": "cannot open file: %s",
   "msg.err.invalid-locale": "invalid language pack: %s",
-  "msg.err.download-failed": "failed to download language pack %s",
+  "msg.err.download-failed": "failed to download %s",
   "msg.err.no-registry-mirror": "no registry mirror configured. Add to ~/.pmm/mirror.ini",
   "msg.err.no-mirror": "no mirrors configured (use: pmm mirror add)",
   "msg.err.no-mirror-file": "no mirror file",

web/mirror/lang/zh-CN.pjson

@@ -86,7 +86,7 @@
   "msg.err.cannot-read": "无法读取 %s",
   "msg.err.cannot-open": "无法打开文件: %s",
   "msg.err.invalid-locale": "无效的语言包: %s",
-  "msg.err.download-failed": "下载语言包 %s 失败",
+  "msg.err.download-failed": "下载 %s 失败",
   "msg.err.no-registry-mirror": "没有配置注册表镜像。请添加到 ~/.pmm/mirror.ini",
   "msg.err.no-mirror": "没有配置镜像源（使用: pmm mirror add）",
   "msg.err.no-mirror-file": "没有镜像配置文件",