fix(ncm §32): 内存瘦身修 OOM 被杀 —— 封面降采样(8.28MB→0.78MB) + 瞬态 rbuf 缩减 + 线程栈显式

真机 dmesg 实锤：OOM Kill ncm (score 460, anon-rss 26.9MB, 设备 56MB)。
画像：封面全分辨率 RGBA 8.28MB(1448x1448 原生解码驻留) 是最大可控块。

瘦身（按收益排序）：
1. sdk meow_ui_img 新增纯增量 meow_img_downscale + cover.c cover_cap(≤480px)
   → 封面 8.28MB→0.78MB，-7.65MB（mem_sim 实测 PASS）。
2. ncm_api.c 瞬态响应 rbuf：song_url→64KB、lyric/song_detail/cloudsearch/user_playlist→256KB
   （detail/track_all 保 1MB）。
3. ncm_app_internal.h 新增 ncm_thread_create（显式 128KB 栈），替换全部 14 处 pthread_create。
4. 滑动窗口/meta 复核零回退（window_sim：608B/首，6000 首 280KB 恒定）。

验证：mem_sim 封面收益 PASS + host home/player 渲染 OK + stream_sim/player_flow_sim/
window_sim/search_sim/cache_evict_sim 全 PASS + test_ncm_core host+mipsel(qemu) PASS
+ build_ncm.sh -Wall -Wextra 0 warning。真机 scp 播放在跑确认（缓存曲，0 播放请求）。

新 ncm md5 44fa16fe（text 1015150/bss 1362500）。正式部署留主会话。

patch_v2/ncm_app/app/logic/appstate.c

@@ -722,7 +722,7 @@ void autoplay_maybe(void)
     meow_log(MEOW_LOG_INFO, "autoplay: triggered, sel='%s'", buf);
     char *sel = strdup(buf);
     pthread_t t;
-    if (pthread_create(&t, NULL, autoplay_worker, sel) == 0) pthread_detach(t);
+    if (ncm_thread_create(&t, autoplay_worker, sel) == 0) pthread_detach(t);
     else free(sel);
 }
 

patch_v2/ncm_app/app/logic/cover.c

@@ -117,6 +117,19 @@ static void save_cover_raw(const char *path, size_t len)
 
 #define COVER_RETRY_MAX 8       /* 连续失败放弃次数（UI 重进页/切歌会重新提交目标） */
 
+/* 内存瘦身：封面解码后按显示上限降采样驻留。网易云全尺寸封面（如 1448×1448）解码成
+ * RGBA = 8MB，而应用显示只需 ≤480px（播放页黑胶方图+歌词页模糊铺底均 ≤ 屏幕 480 宽）——
+ * 缩到 480×480 = 0.9MB，省 ~7MB anon（设备 RAM 仅 56MB，OOM 真机被杀，最高优先级）。
+ * 若已 ≤上限（小缩略图）则原样保留。返回本函数处理后的图（可能替换/释放旧图）。 */
+#define NCM_COVER_DECODE_MAX 480
+static meow_img *cover_cap(meow_img *im)
+{
+    if (!im) return NULL;
+    meow_img *small = meow_img_downscale(im, NCM_COVER_DECODE_MAX);
+    if (small) { meow_img_free(im); return small; }   /* 已缩放：释放原始大图，换小图驻留 */
+    return im;                                          /* 本就够小：保留原图 */
+}
+
 static void *cover_worker(void *arg)
 {
     (void)arg;
@@ -168,6 +181,8 @@ static void *cover_worker(void *arg)
                 }
             }
         }
+        /* 内存瘦身：全尺寸封面解码后降采样到 ≤480px 驻留（省 ~7MB anon，OOM 修复）。 */
+        if (img) img = cover_cap(img);
         if (!img) {
             /* 失败：指数退避重试，连续 COVER_RETRY_MAX 次放弃（不无声死等；
              * 目标保留期间 UI 每帧重请求由 cover_request 去重挡住）。 */
@@ -218,7 +233,7 @@ void cover_request(const char *url)
     pthread_mutex_unlock(&g_cm);
     if (!g_thr_on) {
         g_thr_on = 1;
-        if (pthread_create(&g_thr, NULL, cover_worker, NULL) == 0)
+        if (ncm_thread_create(&g_thr, cover_worker, NULL) == 0)
             pthread_detach(g_thr);
         else
             g_thr_on = 0;

patch_v2/ncm_app/app/ncm_app_internal.h

@@ -18,6 +18,7 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <pthread.h>
+#include <limits.h>
 #include "meow_ui.h"
 #include "meow_ui_view.h"
 #include "ncm.h"          /* 核心库伞头（ctx/api/login/cache/...） */
@@ -81,6 +82,21 @@
 /* active_playlist 哨兵：搜索歌单详情（复用 playlist_open 链路，读 g_st.search_pl_open） */
 #define NCM_PL_SEARCH      (-2)
 
+/* 线程创建：显式小栈（内存瘦身，OOM 修复）。本 App 为 musl 静态二进制，pthread 默认栈
+ * 即 128KB；这里显式声明 128KB（与默认一致、零成本）并防未来 libc/平台默认变化（如
+ * glibc 8MB/thread 的宿主构建）。实测网络/解码调用链栈深 ≤~30KB，128KB 充足。
+ * 返回 pthread_create 结果。 */
+#define NCM_THREAD_STACK   (128 * 1024)
+static inline int ncm_thread_create(pthread_t *t, void *(*fn)(void *), void *arg)
+{
+    pthread_attr_t a;
+    pthread_attr_init(&a);
+    pthread_attr_setstacksize(&a, (size_t)NCM_THREAD_STACK);
+    int r = pthread_create(t, &a, fn, arg);
+    pthread_attr_destroy(&a);
+    return r;
+}
+
 /* ---- 播放/媒体会话状态（play 线程 ↔ UI/IPC 共享，mu 保护）---- */
 enum {
     NCM_PC_STOPPED = 0,

patch_v2/ncm_app/app/play/ipc_media.c

@@ -205,7 +205,7 @@ int ipc_media_start(void)
 {
     if (g_thr_on) return 0;
     g_quit = 0;
-    if (pthread_create(&g_thr, NULL, ipc_thread, NULL) != 0) return -1;
+    if (ncm_thread_create(&g_thr, ipc_thread, NULL) != 0) return -1;
     pthread_detach(g_thr);
     g_thr_on = 1;
     return 0;

patch_v2/ncm_app/app/play/player_manager.c

@@ -369,7 +369,7 @@ static int song_download_attempt(const ncm_song_t *s, int idx, int seq, const ch
     size_t cap = (ext[0] == 'f') ? (1024u << 20) : (64u << 20);
     ss->maxb = (u.size > 0 && (uint64_t)u.size < cap) ? (size_t)u.size : cap;
     ncm_strlcpy(ss->url, u.url, sizeof ss->url);
-    if (pthread_create(&ss->dl_thr, NULL, dl_thread, ss) != 0) {
+    if (ncm_thread_create(&ss->dl_thr, dl_thread, ss) != 0) {
         ncm_cache_abort(ss->w); ss->w = NULL;
         stream_src_close(ss->src); ss->src = NULL;
         return NCM_ERR_IO;
@@ -793,7 +793,7 @@ static void lyric_ensure_worker(void)
     pthread_mutex_lock(&g_lyrmu);
     if (!g_lyr_thr_on) {
         g_lyr_thr_on = 1;
-        if (pthread_create(&g_lyr_thr, NULL, lyric_worker, NULL) == 0) pthread_detach(g_lyr_thr);
+        if (ncm_thread_create(&g_lyr_thr, lyric_worker, NULL) == 0) pthread_detach(g_lyr_thr);
         else g_lyr_thr_on = 0;
     }
     pthread_mutex_unlock(&g_lyrmu);
@@ -825,7 +825,7 @@ int player_manager_start(void)
     g_cache_gb = g_st.cache_limit_gb;
     pthread_mutex_init(&g_play.mu, NULL);
     meow_audio_on_preempt(on_audio_preempt, NULL);   /* 被抢占 → 暂停（SDK 读线程分发） */
-    if (pthread_create(&g_thr, NULL, player_thread, NULL) != 0) return -1;
+    if (ncm_thread_create(&g_thr, player_thread, NULL) != 0) return -1;
     g_thr_on = 1;
     return 0;
 }

patch_v2/ncm_app/app/ui/home.c

@@ -233,7 +233,7 @@ void home_reload(void)
         g_home_loading = 1;
     }
     g_home_thr_on = 1;
-    if (pthread_create(&g_home_thr, NULL, home_worker, NULL) != 0) {
+    if (ncm_thread_create(&g_home_thr, home_worker, NULL) != 0) {
         g_home_thr_on = 0; g_home_loading = 0; g_load_err = NCM_ERR_IO;
     }
     home_apply();

patch_v2/ncm_app/app/ui/login.c

@@ -176,7 +176,7 @@ int login_start(void)
     g_polling = 1;
     g_done = 0;
     g_err = 0;
-    if (pthread_create(&g_thread, NULL, login_worker, NULL) != 0) {
+    if (ncm_thread_create(&g_thread, login_worker, NULL) != 0) {
         g_polling = 0;
         return -1;
     }

patch_v2/ncm_app/app/ui/playlist.c

@@ -306,7 +306,7 @@ static void pl_maybe_ensure(void)
     g_ens_first = 0;
     g_plloading = 1;
     g_plthr_on = 1;
-    if (pthread_create(&g_plthr, NULL, playlist_worker, NULL) != 0) {
+    if (ncm_thread_create(&g_plthr, playlist_worker, NULL) != 0) {
         g_plthr_on = 0; g_plloading = 0; ncm_snack("加载失败");
     }
 }
@@ -340,7 +340,7 @@ void playlist_refresh(void)
     g_pl_stale = 0;
     g_plloading = 1;
     g_plthr_on = 1;
-    if (pthread_create(&g_plthr, NULL, playlist_worker, NULL) != 0) {
+    if (ncm_thread_create(&g_plthr, playlist_worker, NULL) != 0) {
         g_plthr_on = 0; g_plloading = 0; g_load_err = NCM_ERR_IO;
     }
     pl_apply(1);

patch_v2/ncm_app/app/ui/search.c

@@ -211,7 +211,7 @@ static void sr_maybe_load_more(void)
     g_req_tab = g_tab; g_req_offset = n; g_req_replace = 0;
     /* 单飞：无 worker 才发（search_worker 尾部解锁） */
     g_thr_on = 1; g_loading = 1; g_more_err = 0;
-    if (pthread_create(&g_thr, NULL, search_worker, NULL) != 0) {
+    if (ncm_thread_create(&g_thr, search_worker, NULL) != 0) {
         g_thr_on = 0; g_loading = 0; g_more_err = 1;
     }
 }
@@ -270,7 +270,7 @@ void search_submit(const char *kw)
     g_st.search_err = 0;
     g_loading = 1; g_more_err = 0;
     g_thr_on = 1;
-    if (pthread_create(&g_thr, NULL, search_worker, NULL) != 0) {
+    if (ncm_thread_create(&g_thr, search_worker, NULL) != 0) {
         g_thr_on = 0; g_loading = 0; g_st.search_err = NCM_ERR_IO;
     }
     sr_apply();
@@ -290,7 +290,7 @@ static void sr_set_tab(int t)
         g_req_tab = g_tab; g_req_offset = 0; g_req_replace = 1;
         g_loading = 1; g_more_err = 0;
         g_thr_on = 1;
-        if (pthread_create(&g_thr, NULL, search_worker, NULL) != 0) {
+        if (ncm_thread_create(&g_thr, search_worker, NULL) != 0) {
             g_thr_on = 0; g_loading = 0;
         }
     }
@@ -354,7 +354,7 @@ int search_on_tap(int x, int y)
                     g_req_tab = g_tab; g_req_offset = 0; g_req_replace = 1;
                     g_loading = 1;
                     g_thr_on = 1;
-                    if (pthread_create(&g_thr, NULL, search_worker, NULL) != 0) {
+                    if (ncm_thread_create(&g_thr, search_worker, NULL) != 0) {
                         g_thr_on = 0; g_loading = 0; g_st.search_err = NCM_ERR_IO;
                     }
                 }