MeowOS-For-R3P2/patch_v2/meow_audiod/meow_audiod.c

#define _GNU_SOURCE

/* meow_audiod.c — MeowOS 独占音频服务（devdocs/plan/AUDIOD_DESIGN.md）。
 *
 * 定位：把**所有与声卡硬件的交互**收敛到本守护（svcd 托管，板载 /usr/bin/meow_audiod）。
 * App 只经 SDK 客户端 API（meow_ui_audio.c）喂 PCM；audiod 独占持有 hw:0,0。
 *
 * 核心设计（用户定案，勿推翻）：
 *   - 独占 + 抢占（后开流赢，旧流收 MSG_AUDIO_PREEMPTED 并被置 draining，PCM 丢弃）；
 *     软混音已否决（MIPS32 软 SRC 伤音质），留混音器接口位（v1 不实现）。
 *   - 单进程双线程（+路由线程）：IO 线程（accept/读帧/解析/ring 写）、播放线程
 *     （独占 ALSA 直开，从 ring 取数写 DAC，xrun PREPARE 恢复）、路由线程
 *     （轮询 headset/balance 插孔 switch 状态 → amixer cset numid=9）。
 *   - 格式归一 = 协商：grant_rate/ch/fmt 回客户端应产出的格式（SDK 负责 mono→stereo
 *     复制 / S16↔S32 定值升降位）；audiod 只做「硬件最优」格式的字节管道。
 *   - DAC 原生率跟随（无 SRC）；切率 mute-重配-恢复。
 *   - meow_route 已并入（§5）：本进程在=路由在；独立 meow_route 服务退役。
 *
 * 启动门控（红线）：main() 先读 /tmp/meow_boot_mode；非 "meow" → 日志一行 → exit(0)
 *   （HibyOS 模式下 audiod 物理不存在，绝不碰声卡）。测试/宿主用 env MEOW_AUDIO_FORCE=1
 *   跳过门控。
 *
 * 防卡死护栏（2026-09-01，真机长流卡死教训——驱动 wedge 时绝不允许级联冻死全守护）：
 *   - ring 写**有界等待**（MEOW_AUDIO_RING_WAIT_MS，缺省 5000ms）：超时丢弃该 PCM 块并计数
 *     （dropped=），IO 线程永不永久睡眠 → accept/读循环永生；
 *   - 所有 cond 等待均为 timedwait（1s 周期自愈，防丢失唤醒）；
 *   - popen(amixer) 收割有界：WNOHANG + SIGKILL + 仍不死则放弃收割（宁可泄漏不卡线程）；
 *   - ALSA 写改 O_NONBLOCK + poll(POLLOUT,1s)：连续 3 次停摆判定设备 wedge → 关卡进入
 *     丢弃模式（stall=），下一路 OPEN 重开重试；
 *   - server→client 下行帧单发 write，写不全即整帧丢弃（txdrop=），绝不因客户端不读堵 IO 循环；
 *   - 主线程 watchdog：IO/播放线程心跳 10s 无活动即告警日志；
 *   - io 线程 poll 出错只记日志不退出（listener 不丢）。
 *
 * 音频路径双形态：
 *   - 真机/ALSA：env MEOW_AUDIO_SINK 缺省自动检测 /dev/snd/pcmC0D0p ∈ 存在 → open ALSA UAPI
 *     （非 mmap：HW_PARAMS + PREPARE + write）。musl 的 sound/asound.h masks/intervals 是
 *     重索引数组（见 audio_out.c 注释），访问须减 FIRST_MASK/FIRST_INTERVAL。
 *   - 无 ALSA（宿主/qemu）：自动回退 FILE sink（写 WAV）或 NULL（env MEOW_AUDIO_SINK=null）。
 *
 * 编译（mipsel 静态）：build_audiod.sh。宿主编译：build_audiod.sh host。
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <time.h>
#include <poll.h>
#include <pthread.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/wait.h>
#include "meow_ipc.h"
#include "bt_dev.h"               /* P2：DEV 自识别（a2dpsrc 端点 → MAC → alsa.conf 幂等改写） */

#ifdef __linux__
#include <sound/asound.h>
#include <sys/ioctl.h>
#define AUDIOD_HAVE_ALSA 1
#endif

/* ---- 缺省路径 ---- */
#define AUD_SOCK_DEFAULT   "/usr/data/meow_audio.sock"
#define DEV_PCM            "/dev/snd/pcmC0D0p"
#define LOG_DIR_CARD       "/usr/data/mnt/sd_0/MeowOS/logs"
#define BOOT_MODE_PATH     "/tmp/meow_boot_mode"
#define BOOTTS_CACHE       "/tmp/meow_bootts"
#define SETTINGS_CONF      "/usr/data/meow/settings.conf"
#define DEFAULT_OUT_WAV    "/tmp/meow_audiod.wav"

/* ---- 蓝牙 A2DP source（P2 输出目标 OUT_BT） ---- */
#define BT_PCM_DEFAULT     "pcm.bluealsa"   /* alsa.conf `pcm.bluealsa`(plug→bluealsa)；aplay -D bluealsa 等价 */
#define BT_PCM_FALLBACK    "bluealsa"       /* 部分配置只定义别名节点，防打开失败再试一次 */
#define BT_CODEC_AUTO      "auto"
#define BT_VOL_FULL_PCM    "/usr/bin/bluealsa-cli"   /* 一键设 AVRCP 100%（best-effort，不存在则跳过） */

#define CLI_MAX            8          /* 同连客户端上限（防 fd 泄漏） */
#define READ_BUF_MAX       (MEOW_IPC_MAX + MEOW_IPC_HDR_LEN)
#define FRAME_READ_MAX     (MEOW_IPC_MAX + MEOW_IPC_HDR_LEN)
#define READ_CHUNK         8192       /* 播放线程单次从 ring 取出的字节上限（帧对齐裁剪） */
#define VOL_DEFAULT        60         /* settings.conf audio.volume 缺省 */
#define RING_MIN           4096
#define RING_MAX           (1u << 20)
#define RING_WAIT_DEFAULT  5000       /* ring 满时 IO 线程等待上限 ms（超时丢弃，防背压变死锁） */
#define COND_WAIT_MS       1000       /* 播放线程 cond 周期醒（自愈丢失唤醒 + 响应 g_stop） */
#define ALSA_POLL_MS       1000       /* ALSA 可写 poll 超时；连续 ALSA_STALL_MAX 次判定 wedge */
#define ALSA_STALL_MAX     3
#define WD_SILENT_SEC      10         /* watchdog：线程心跳静默上限（> RING_WAIT 余量） */

/* 客户端流状态 */
enum { CLS_OPEN = 0, CLS_PAUSED = 1, CLS_DRAINING = 2 };   /* DRAINING=被抢占，PCM 丢弃 */

/* Sink 枚举 */
enum { SINK_ALSA = 0, SINK_FILE = 1, SINK_NULL = 2 };
static int  g_sink = SINK_ALSA;
static int  g_hw_fmt = AUDIO_FMT_S16;   /* 硬件最优格式（ALSA 探测；FILE/NULL=S16） */
static int  g_hw_probed = 0;

/* 输出目标（BLUETOOTH_FULL_OVERHAUL_PLAN §五）：OUT_DAC=本地 hw:0,0；OUT_BT=蓝牙 A2DP source。
 * **BT 是独立目标，不共用 DAC 逻辑**：period=1024×4/FPGA numid=9/音量反转均不得作用于 BT。 */
static int     g_target = AUDIO_OUT_DAC;
static char    g_bt_codec[24] = BT_CODEC_AUTO;  /* settings.conf `bt.codec`（auto/SBC/AAC/aptX/LDAC…） */
static char    g_settings_path[256] = SETTINGS_CONF;  /* MEOW_AUDIO_SETTINGS 可覆盖（宿主测） */

static char g_sock[108] = AUD_SOCK_DEFAULT;
static char g_out_wav[256] = DEFAULT_OUT_WAV;
static const char *g_amixer = "/usr/bin/amixer";  /* 环境可覆盖 */
static int  g_route_manual = -1;        /* -1=auto；2=3.5；3=4.4 */
static int  g_route_cur = -1;           /* 最近已知路由；-1=未知 */
static int  g_vol_pct = VOL_DEFAULT;    /* 当前音量 0-100（缓存：DAC 音量；BT 时 volctl=avrcp） */
static int  g_force = 0;                /* MEOW_AUDIO_FORCE=1 跳过启动门控（宿主/qemu 测试） */

/* ---- 缓冲状态（+日志） ---- */
static char g_logfile[300] = "";
static int  g_logfd = -1;

static volatile sig_atomic_t g_stop = 0;

/* ---- 共享态（g_mu 保护 + g_cond 唤醒；g_cond 用 CLOCK_MONOTONIC，main 中初始化） ---- */
/* 前向声明（供 cli_free/dispatch/播放线程使用；定义见下） */
static void session_end_locked(void);
static void session_clean_locked(void);
static void _audio_mark_reconfig_needed(void);
static pthread_mutex_t g_mu = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  g_cond;

struct client {
    int         used;
    int         fd;
    char        app_id[MEOW_APP_ID_MAX];
    uint32_t    sid;
    int         state;                /* CLS_* */
    uint8_t     rbuf[READ_BUF_MAX];
    size_t      rlen;
};
static struct client g_cli[CLI_MAX];

/* 当前授权流（喂养 DAC 的唯一流） */
struct stream_info {
    int         active;
    uint32_t    sid;
    char        app_id[MEOW_APP_ID_MAX];
    uint32_t    rate;
    uint16_t    ch;                   /* grant ch（DAC 双声道 → 2） */
    uint16_t    fmt;                  /* grant fmt */
};
static struct stream_info g_st;

static int     g_paused = 0;          /* 当前流被暂停 */
static uint32_t g_next_sid = 1;
static uint64_t g_written_frames = 0; /* 当前流：客户端写入 ring 的帧 */
static uint64_t g_played_frames = 0;  /* 当前流：播放线程写到设备的帧 */
static uint32_t g_underrun = 0;
static uint64_t g_drop_frames = 0;    /* ring 满超时丢弃的帧（背压护栏，QUERY dropped=） */
static uint32_t g_stall = 0;          /* ALSA 可写 poll 超时次数（设备停摆；QUERY stall=） */
static uint32_t g_txdrop = 0;         /* server→client 下行帧丢弃（客户端不读；QUERY txdrop=） */

/* ring 写等待上限（env MEOW_AUDIO_RING_WAIT_MS 覆盖；测试用小值） */
static int     g_ring_wait_ms = RING_WAIT_DEFAULT;

/* 线程心跳（watchdog 用；宽松计数，不加锁） */
static volatile unsigned g_hb_io = 0;
static volatile unsigned g_hb_play = 0;

/* 测试钩子（仅 env 显式开启；MEOW_AUDIO_TEST_WRITE_DELAY_MS / _WEDGE_AFTER_BYTES / _AMIXER_TRACE） */
static int      g_test_write_delay_ms = 0;
static long long g_test_wedge_after = -1;   /* dev_write 累计字节≥此值后模拟设备 wedge（睡到 g_stop） */
static uint64_t g_dev_bytes = 0;
static char     g_amixer_trace_path[256] = "";   /* MEOW_AUDIO_AMIXER_TRACE：记录每次 amixer cset */

/* ring（SPSC：IO 线程写，播放线程读；g_mu + g_cond 保护） */
static uint8_t *g_ring = NULL;
static size_t   g_ring_cap = 0;
static size_t   g_rpos = 0, g_wpos = 0;

/* 播放线程设备状态 */
static int     g_dev_fd = -1;
static int     g_dev_open = 0;
static uint32_t g_dev_rate = 0, g_dev_ch = 0, g_dev_fmt = 0;
static int     g_dev_dsd = 0;            /* 当前打开设备为 DoP DSD（决定 DOP_EN 硬件时序；g_mu 保护） */
static int     g_reconfig_pending = 0;

/* ---- 蓝牙 A2DP source 运行时状态（g_mu 保护；仅 g_target==OUT_BT && g_sink==SINK_ALSA 时用） ----
 * 直接调用 libasound 插件 PCM（pcm.bluealsa）。audiod 以动态 glibc 链接设备 libasound.so.2
 * （见 bt_* 段注释），此处仅存 snd_pcm_t 不透明句柄。 */
static void    *g_bt_hdl = NULL;        /* snd_pcm_t *（libasound 不透明句柄） */
static int      g_bt_open = 0;          /* BT PCM 已打开 */
static int      g_bt_vol_full_done = 0; /* 已对 AVRCP 置 100%（幂等，一次即可） */

/* ---- 数字域电平表（DAC 实时监控；CS43198 无模拟电平回读，播放线程看 PCM 样本） ----
 * 播放线程对从 ring 取出的每块 PCM 做纯整数累加（归一到 16bit 域：S24/S32 >>16），
 * ~100ms 窗口（rate/10 帧）到点才结算一次 RMS/peak 并发布快照——每帧仅几次整数加乘，
 * 不拖慢播放线程；无流时无数据读出即零开销。不用浮点（MIPS 软浮点昂贵）。 */
#define METER_FLOOR_DB10   (-990)    /* 静音地板 -99.0 dBFS */
static uint64_t g_m_sumsq  = 0;      /* 窗口内样本平方和（16bit 域） */
static uint32_t g_m_peak   = 0;      /* 窗口峰值（0..32768） */
static uint32_t g_m_frames = 0;      /* 窗口已计帧 */
static uint32_t g_m_win    = 0;      /* 窗口目标帧数（rate/10；0=未配置/无流） */
/* 发布快照（g_mu 保护；deci-dB，METER_FLOOR_DB10=静音） */
static int      g_lvl_rms_db10  = METER_FLOOR_DB10;
static int      g_lvl_peak_db10 = METER_FLOOR_DB10;
static uint32_t g_lvl_seq = 0;       /* 快照代际（每次结算/开流复位递增） */

/* ---- 全面监控日志（主线程 1s 节拍写；流活跃才写，流停止即停写，无流零开销） ---- */
static int      g_monfd = -1;
static uint64_t g_mon_prev_played = 0;
static int64_t  g_mon_prev_ms = 0;

/* ---- 日志 ---- */
static void logmsg(const char *fmt, ...)
{
    if (g_logfd < 0) return;
    char b[512];
    va_list ap;
    va_start(ap, fmt);
    int n = vsnprintf(b, sizeof b, fmt, ap);
    va_end(ap);
    if (n < 0) return;
    if (n > (int)sizeof b - 1) n = (int)sizeof b - 1;
    if (write(g_logfd, "[audiod] ", 9) < 0) { }
    if (write(g_logfd, b, (size_t)n) < 0) { }
    if (write(g_logfd, "\n", 1) < 0) { }
    /* 同时到 stderr（supervisor/svcd 捕获 + 真机 SSH 直达） */
    fprintf(stderr, "[audiod] %s\n", b);
}

/* ---- bootts 复用（与 launcher 共用 /tmp/meow_bootts 缓存，一次开机一份日志） ---- */
static void get_bootts(char *out, size_t n)
{
    int fd = open(BOOTTS_CACHE, O_RDONLY);
    if (fd >= 0) {
        int r = read(fd, out, (int)n - 1);
        close(fd);
        if (r > 0) { out[r] = 0; return; }
    }
    time_t now = time(NULL), up = 0;
    fd = open("/proc/uptime", O_RDONLY);
    if (fd >= 0) {
        char buf[64];
        int r = read(fd, buf, sizeof buf - 1);
        close(fd);
        if (r > 0) { buf[r] = 0; char *p = strchr(buf, ' '); if (p) *p = 0; up = (time_t)atof(buf); }
    }
    struct tm tm;
    localtime_r(&now - up, &tm);
    strftime(out, n, "meow_%Y%m%d_%H%M%S", &tm);
    fd = open(BOOTTS_CACHE, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (fd >= 0) { if (write(fd, out, strlen(out)) < 0) { } close(fd); }
}

static void log_open(void)
{
    char ts[64];
    get_bootts(ts, sizeof ts);
    if (access(LOG_DIR_CARD, W_OK) == 0)
        snprintf(g_logfile, sizeof g_logfile, "%s/%s.log", LOG_DIR_CARD, ts);
    else
        snprintf(g_logfile, sizeof g_logfile, "/tmp/%s.log", ts);
    g_logfd = open(g_logfile, O_WRONLY | O_CREAT | O_APPEND, 0644);
}

/* ---- 启动门控 ---- */
static int boot_mode_ok(void)
{
    if (g_force) return 1;
    FILE *f = fopen(BOOT_MODE_PATH, "r");
    if (!f) return 0;                 /* 文件缺失=非 meow（未知安全默认） */
    char buf[16] = "";
    if (fscanf(f, "%15s", buf) != 1) { fclose(f); return 0; }
    fclose(f);
    return strcmp(buf, "meow") == 0;
}

/* ---- 帧发送（仅 IO 线程用：OPEN_ACK/STATE/PREEMPTED/ACK） ---- */
/* 单发即丢：客户端 fd 是 O_NONBLOCK；拼装整帧一次 write()，写不全（对端不读/缓冲满）
 * 就整帧丢弃并计数——绝不为慢客户端堵 IO 循环，也绝不写出半个帧让对端协议错位。
 * 丢 OPEN_ACK/ACK 的后果 = 客户端 3s 超时判流死重连（可接受）；丢 PREEMPTED 由 App 侧
 * 播放停摆自检兜底。 */
static int send_frame(int fd, uint16_t type, uint32_t req_id, const void *payload, uint32_t len)
{
    if (len > MEOW_IPC_MAX) return -1;
    uint8_t frame[MEOW_IPC_HDR_LEN + MEOW_IPC_MAX];
    uint32_t magic = MEOW_IPC_MAGIC;
    uint16_t ver = MEOW_IPC_VERSION;
    memcpy(frame + 0, &magic, 4);
    memcpy(frame + 4, &ver, 2);
    memcpy(frame + 6, &type, 2);
    memcpy(frame + 8, &req_id, 4);
    memcpy(frame + 12, &len, 4);
    if (len && payload) memcpy(frame + MEOW_IPC_HDR_LEN, payload, len);
    size_t total = MEOW_IPC_HDR_LEN + len;
    ssize_t w = write(fd, frame, total);
    if (w != (ssize_t)total) {
        g_txdrop++;
        if ((g_txdrop & 63u) == 1u)
            logmsg("tx drop: fd=%d type=0x%04x len=%u wrote=%zd (total x%u, client not reading?)",
                   fd, (unsigned)type, (unsigned)len, w, (unsigned)g_txdrop);
        return -1;
    }
    return 0;
}

/* cond 有界等待（g_cond 为 CLOCK_MONOTONIC；调用方已持 g_mu）。 */
static void cond_wait_tmo(int ms)
{
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    ts.tv_sec += ms / 1000;
    ts.tv_nsec += (long)(ms % 1000) * 1000000L;
    if (ts.tv_nsec >= 1000000000L) { ts.tv_sec++; ts.tv_nsec -= 1000000000L; }
    pthread_cond_timedwait(&g_cond, &g_mu, &ts);
}

/* ---- frame 大小/位深 ---- */
static int fmt_bps(int fmt)
{
    switch (fmt) {
    case AUDIO_FMT_S16: return 2;
    case AUDIO_FMT_S24:
    case AUDIO_FMT_S32:
    case AUDIO_FMT_FLOAT:
    case AUDIO_FMT_DOP: return 4;    /* DOP=32-bit DoP 容器（16bit DSD + 8bit 标记 + 8bit 0），与 S32 同宽 */
    default: return 2;
    }
}
static const char *fmt_name(int fmt)
{
    switch (fmt) {
    case AUDIO_FMT_S16: return "S16";
    case AUDIO_FMT_S24: return "S24";
    case AUDIO_FMT_S32: return "S32";
    case AUDIO_FMT_FLOAT: return "FLOAT";
    case AUDIO_FMT_DOP: return "DoP";
    default: return "?";
    }
}
static int frame_size(void) { return g_st.ch * fmt_bps(g_st.fmt); }

/* 输出目标名（日志/QUERY 用） */
static const char *target_name(void)
{
    return (g_target == AUDIO_OUT_BT) ? "bt" : "dac";
}

/* 授权给客户端的硬件最优格式。native_fmt=客户端请求格式。BT（A2DP source）=S16（codec 基座，
 * pcm.bluealsa 前置 plug 层自动转 codec 协商率）；DAC=hw 探测最优（S32 升位/S16 直通）；
 * FILE/NULL 宿主 sink：S24/S32 按请求**byte-exact 透传**（高清实测保真），S16 缺省，DOP 恒透传。 */
static int target_grant_fmt(int native_fmt)
{
    if (native_fmt == AUDIO_FMT_DOP) return AUDIO_FMT_DOP;          /* DoP 恒透传（audiod 只做管道） */
    if (g_target == AUDIO_OUT_BT) return AUDIO_FMT_S16;
    if (g_sink == SINK_ALSA) return g_hw_fmt;                        /* DAC 探测最优（S32 偏好） */
    if (native_fmt == AUDIO_FMT_S24 || native_fmt == AUDIO_FMT_S32)
        return native_fmt;                                           /* FILE/NULL：高保真记录 */
    return AUDIO_FMT_S16;
}

/* 音量控制归属（QUERY volctl=）：dac=反转控制；avrcp=蓝牙 AVRCP 侧控。 */
static const char *volctl_name(void)
{
    return (g_target == AUDIO_OUT_BT) ? "avrcp" : "dac";
}

/* 整数开平方（uint64→uint32，逐位法；替代软浮点 sqrt） */
static uint32_t isqrt64(uint64_t x)
{
    uint64_t r = 0, bit = 1ULL << 62;
    while (bit > x) bit >>= 2;
    while (bit) {
        if (x >= r + bit) { x -= r + bit; r = (r >> 1) + bit; }
        else r >>= 1;
        bit >>= 2;
    }
    return (uint32_t)r;
}

/* 线性幅度（16bit 域 0..32768）→ deci-dBFS（×10 整数，相对满幅 32768）。
 * log2 = 整数位 +  octave 内线性插值；最大误差 ~0.5dB，电平表/日志足够。 */
static int db10_of_lin(uint32_t v)
{
    if (v == 0) return METER_FLOOR_DB10;
    if (v > 32768) v = 32768;
    int b = 0;
    uint32_t t = v;
    while (t >>= 1) b++;                 /* b = floor(log2(v)) ∈ 0..15 */
    uint32_t frac = v - (1u << b);
    /* 20*log10(2)*10 = 60.206 */
    int64_t db10 = (int64_t)60206 * (b - 15) / 1000;
    db10 += (int64_t)60206 * (int64_t)frac / ((int64_t)1000 << b);
    if (db10 < METER_FLOOR_DB10) db10 = METER_FLOOR_DB10;
    return (int)db10;
}

/* 窗口结算 + 发布快照（调用方已持 g_mu） */
static void meter_window_end(void)
{
    uint64_t samples = (uint64_t)g_m_frames * (g_st.ch ? g_st.ch : 2);
    uint32_t rms = samples ? isqrt64(g_m_sumsq / samples) : 0;
    g_lvl_rms_db10  = db10_of_lin(rms);
    g_lvl_peak_db10 = db10_of_lin(g_m_peak);
    g_lvl_seq++;
    g_m_sumsq = 0; g_m_peak = 0; g_m_frames = 0;
}

/* 喂一块 PCM 进电平表（调用方已持 g_mu，播放线程 ring_read 后紧跟调用）。
 * 逐样本整数累加；**逐帧判窗口边界**（帧循环里一次加+比较，开销可忽略）——
 * 若按块末尾才结算，块越过窗口边界的部分会混进旧窗口（宿主流失真正弦+静音
 * 混合窗口实测 rms 偏差 7dB+）。fmt 为 grant 格式；S24/S32 归一 >>16。 */
static void meter_feed(const uint8_t *buf, size_t n)
{
    if (!g_m_win) return;
    int bps = fmt_bps(g_st.fmt);
    int ch = g_st.ch ? (int)g_st.ch : 2;
    size_t fs = (size_t)ch * (size_t)bps;
    if (fs == 0) return;
    size_t frames = n / fs;
    for (size_t i = 0; i < frames; i++) {
        const uint8_t *p = buf + i * fs;
        for (int c = 0; c < ch; c++, p += bps) {
            int32_t v;
            if (bps == 2) { int16_t s; memcpy(&s, p, 2); v = s; }
            else          { int32_t s; memcpy(&s, p, 4); v = s >> 16; }
            uint32_t a = (v < 0) ? (uint32_t)(-(int64_t)v) : (uint32_t)v;
            g_m_sumsq += (uint64_t)a * a;
            if (a > g_m_peak) g_m_peak = a;
        }
        if (++g_m_frames >= g_m_win) meter_window_end();
    }
}

static size_t ring_bytes(void)          /* 已缓冲字节 */
{
    return (g_wpos >= g_rpos) ? (g_wpos - g_rpos) : (g_ring_cap - g_rpos + g_wpos);
}

/* 播放线程读整块（调用方已持 g_mu；返回实际移动字节，帧对齐裁剪） */
static size_t ring_read_locked(uint8_t *dst, size_t want)
{
    size_t avail = ring_bytes();
    size_t fs = (size_t)frame_size();
    if (fs == 0) fs = 1;
    if (avail > want) avail = want;
    size_t n = (avail / fs) * fs;       /* 帧对齐 */
    if (n == 0) return 0;
    size_t first = g_ring_cap - g_rpos;
    size_t take = n < first ? n : first;
    memcpy(dst, g_ring + g_rpos, take);
    if (take < n) memcpy(dst + take, g_ring, n - take);
    g_rpos = (g_rpos + n) % g_ring_cap;
    pthread_cond_signal(&g_cond);       /* 腾出空间唤醒阻塞的 ring 写入方（IO 线程） */
    return n;
}

/* IO 线程写整块（调用方已持 g_mu）。**有界等待**：ring 满最多等 g_ring_wait_ms，
 * 超时丢弃该块（返回 0）——背压绝不能退化成 IO 线程永久睡眠（真机长流卡死根因：
 * 播放线程堵死 → ring 满 → IO cond_wait 永不醒 → accept 停摆 → 全链冻结）。
 * sid 为写入方开流时的代际：等待期间被抢占（g_st.sid 变化）立即丢弃（返回 0），
 * 防止旧流 PCM 注入新流 ring（ring_rebuild 后错位）。
 * 返回实际写入字节数；0=被丢弃（超时/流死/被抢占）。 */
static size_t ring_write_locked(const uint8_t *src, size_t want, uint32_t sid)
{
    size_t fs = (size_t)frame_size();
    if (fs == 0) fs = 1;
    size_t n = (want / fs) * fs;
    if (n == 0) return 0;
    if (!g_ring || g_ring_cap < n) return 0;        /* ring 未建/异常小：直接丢 */
    struct timespec deadline;
    clock_gettime(CLOCK_MONOTONIC, &deadline);
    deadline.tv_sec += g_ring_wait_ms / 1000;
    deadline.tv_nsec += (long)(g_ring_wait_ms % 1000) * 1000000L;
    if (deadline.tv_nsec >= 1000000000L) { deadline.tv_sec++; deadline.tv_nsec -= 1000000000L; }
    for (;;) {
        if (g_stop) return 0;
        /* 流失效/代际变化：非当前授权、被抢占、被停止 → 丢弃 */
        if (!g_st.active || g_st.sid != sid)
            return 0;
        size_t freeb = g_ring_cap - ring_bytes();
        if (freeb >= n) break;
        int wr = pthread_cond_timedwait(&g_cond, &g_mu, &deadline);
        if (wr == ETIMEDOUT) {
            g_drop_frames += n / fs;
            static unsigned s_droplog = 0;
            if ((s_droplog++ & 63u) == 0)
                logmsg("ring full >%dms: dropped %zu bytes (total dropped=%llu frames, playback stuck?)",
                       g_ring_wait_ms, n, (unsigned long long)g_drop_frames);
            return 0;
        }
    }
    size_t wpos = g_wpos;
    size_t first = g_ring_cap - wpos;
    size_t take = n < first ? n : first;
    memcpy(g_ring + wpos, src, take);
    if (take < n) memcpy(g_ring, src + take, n - take);
    g_wpos = (g_wpos + n) % g_ring_cap;
    pthread_cond_signal(&g_cond);
    return n;
}

/* 重建 ring（调用方已持 g_mu；按当前授权流参数算 ~200ms 容量；重建=清空旧流缓冲） */
static void ring_rebuild(void)
{
    size_t fs = (size_t)frame_size();
    if (fs == 0) fs = 1;
    size_t want = (size_t)((uint64_t)g_st.rate * fs / 5);   /* 0.2s */
    if (want < RING_MIN) want = RING_MIN;
    if (want > RING_MAX) want = RING_MAX;
    size_t cap = (want / fs) * fs;
    if (cap < fs) cap = fs;
    free(g_ring);
    g_ring = malloc(cap);
    g_ring_cap = g_ring ? cap : 0;
    if (!g_ring) g_ring_cap = 0;
    g_rpos = g_wpos = 0;
    logmsg("ring rebuilt: cap=%zu bytes (~%u ms @ %uHz %s x%u)",
           g_ring_cap, (unsigned)(g_ring_cap ? g_ring_cap * 1000 / ((uint64_t)g_st.rate * fs) : 0),
           (unsigned)g_st.rate, fmt_name(g_st.fmt), (unsigned)g_st.ch);
}

/* ---- amixer 封装（popen 限时；无 amixer → 优雅失败） ---- */
/* 读子进程 stdout（非阻塞+poll 限时）。收割**必须有界**：驱动 wedge 时 amixer 可能
 * 挂在内核 ioctl 里，无条件 waitpid 会把调用线程（路由线程持 g_mu / IO 线程）一起拖死
 * ——真机长流卡死的级联路径之一。策略：先 WNOHANG 等 300ms；不死 → SIGKILL 再等 300ms；
 * 仍不死（D 态）→ 放弃收割（泄漏一个子进程，换线程不卡死；已记日志）。 */
static char *popen_read_tmo(int tmo_ms, const char *cmd)
{
    int p[2];
    if (pipe(p) < 0) return NULL;
    pid_t pid = fork();
    if (pid < 0) { close(p[0]); close(p[1]); return NULL; }
    if (pid == 0) { dup2(p[1], 1); close(p[0]); close(p[1]); execl("/bin/sh", "sh", "-c", cmd, (char *)0); _exit(127); }
    close(p[1]);
    fcntl(p[0], F_SETFL, fcntl(p[0], F_GETFL, 0) | O_NONBLOCK);
    static char buf[4096];
    size_t off = 0;
    int remain = tmo_ms;
    while (remain > 0 && off < sizeof buf - 1) {
        struct pollfd pf = { p[0], POLLIN, 0 };
        int r = poll(&pf, 1, remain);
        if (r < 0) { if (errno == EINTR) continue; break; }
        if (r == 0) break;
        ssize_t rd = read(p[0], buf + off, sizeof buf - 1 - off);
        if (rd == 0) break;
        if (rd < 0) { if (errno == EAGAIN || errno == EWOULDBLOCK) continue; break; }
        off += (size_t)rd;
    }
    close(p[0]);
    int reaped = 0;
    for (int i = 0; i < 30; i++) {          /* 300ms 优雅退出窗口 */
        if (waitpid(pid, NULL, WNOHANG) == pid) { reaped = 1; break; }
        struct timespec ts = { 0, 10 * 1000000L };
        nanosleep(&ts, NULL);
    }
    if (!reaped) {
        logmsg("popen: child %ld did not exit in 300ms, SIGKILL (%s)", (long)pid, cmd);
        kill(pid, SIGKILL);
        for (int i = 0; i < 30; i++) {
            if (waitpid(pid, NULL, WNOHANG) == pid) { reaped = 1; break; }
            struct timespec ts = { 0, 10 * 1000000L };
            nanosleep(&ts, NULL);
        }
        if (!reaped)
            logmsg("popen: child %ld unkillable (D-state, driver wedged?) — abandon reap", (long)pid);
    }
    buf[off] = 0;
    return buf;
}

static int amixer_set(int numid, int val, int card)
{
    char cmd[160];
    snprintf(cmd, sizeof cmd, "%s%s cset numid=%d %d >/dev/null 2>&1",
             g_amixer, (card ? " -c 0" : ""), numid, val);
    char *o = popen_read_tmo(1500, cmd);
    if (!o) return -1;
    /* 测试钩子（仅 env MEOW_AUDIO_AMIXER_TRACE=<path>）：把每次 amixer cset 追加到文件，
     * 供宿主断言「音量双组写」PCM+DSD_VOLUME 是否成对下发（真机无 amixer 时不写/不报错）。 */
    if (g_amixer_trace_path[0]) {
        int tfd = open(g_amixer_trace_path, O_WRONLY | O_CREAT | O_APPEND, 0644);
        if (tfd >= 0) {
            char tb[64];
            int tn = snprintf(tb, sizeof tb, "cset numid=%d %d\n", numid, val);
            if (tn > 0) { if (write(tfd, tb, (size_t)tn) < 0) { } }
            close(tfd);
        }
    }
    /* popen_read_tmo 用的是静态缓冲，这里不 free（与 meow_route.c 同权衡） */
    return 0;
}

static int amixer_get(int numid, int card)
{
    char cmd[160];
    snprintf(cmd, sizeof cmd, "%s%s cget numid=%d 2>/dev/null", g_amixer, (card ? " -c 0" : ""), numid);
    char *o = popen_read_tmo(1500, cmd);
    if (!o) return -1;
    const char *ln = o;
    while (ln && *ln) {
        const char *nl = strchr(ln, '\n');
        const char *p = ln;
        while (*p == ' ' || *p == '\t') p++;
        if (p[0] == ':' && strncmp(p, ": values=", 9) == 0) { int v = atoi(p + 9); return v; }
        if (!nl) break;
        ln = nl + 1;
    }
    return -1;
}

/* ---- DSD（DoP）相关常量 + 状态 ----
 * ⚠️ 真机核实项（AUDIOD_A3_DSD_PLAN §五，未做）：DSD_VOLUME_A/B 寄存器地址/control、DoP 标记字节
 * （0x05/0xFA vs 0xA5/0x5A）。下述 numid 为设计定案占位：DOP_EN=numid 10（plan §三「cset numid=10 1」），
 * DSD_VOLUME 单 control 占位 numid 11（真实为 A/B 两路或 write_reg_val，待 DS1039 核实）。
 * 未核实前 DSD_VOLUME 写为 best-effort（amixer 出错仅日志，绝不掩盖；正确地址真机定后再上）。 */
#define DOP_EN_NUMID   10
#define DSD_VOL_NUMID  11
static int g_dsd_active = 0;   /* 当前授权流为 DoP DSD（g_mu 保护；决定 DOP_EN=1 与 DSD 音量作用域） */

static void dac_vol_set(int pct)
{
    int t = 100 - pct, dac;
	if (pct <= 0) dac = 255;                    /* 真静音（DS1039：255=-127.5dB） */
	else dac = t * t * 192 / 10000;             /* 感知平方锥度：dB 衰减=(1-pct)^2×96dB */
	if (dac > 255) dac = 255;
	if (dac < 0) dac = 0;  /* CS43198=衰减量(0最响255静音)+平方锥度(听感线性) */
    /* 音量收编 v2：**泛化双组写**——同刻写 PCM(numid=1/2) 与 DSD_VOLUME，保证 DSD↔PCM 切换
     * 音量连续 + 防爆音闭环（决策①，勿只写 PCM）。锥度沿用平方（决策②）。 */
    amixer_set(1, dac, 1);
    amixer_set(2, dac, 1);
    amixer_set(DSD_VOL_NUMID, dac, 1);
    logmsg("DAC/DSD vol -> %d%% (PCM L/R=%d, DSD=%d)", pct, dac, dac);
}

static void dac_vol_mute(void)
{
    /* CS43198 寄存器=衰减量（0=最响 255=静音）。⚠️ 写 0 是「最大响度」不是静音——
     * 旧版写 0 在闪退/重配瞬间造成满幅炸音（真机事故 2026-09-01）。真静音写 255。 */
    amixer_set(1, 255, 1);
    amixer_set(2, 255, 1);
    amixer_set(DSD_VOL_NUMID, 255, 1);   /* DSD 同步真静音（防爆音闭环：DSD 也 255） */
}

/* ---- DSD（DoP）管道：audiod 只做 DOP_EN 时序 + DSD 音量 + 透传；不引 dsd2pcm（许可未核实，避风险）。
 * 流级判定 vs 设备级判定分拆：
 *   - g_dsd_active：当前授权流为 DoP DSD（dispatch 授 DOP 时置位，session_clean 复位）——供 QUERY/monitor。
 *   - g_dev_dsd：当前**打开的设备**为 DSD（reconfigure/dev_open 后置位）——决定 DOP_EN 硬件时序。
 * 进入 DSD（plan §三时序）由播放线程 reconfigure 执行：mute(PCM+DSD) → DOP_EN=1 → hw_params(容器率)
 * → dac_vol_set(DSD_VOLUME) → unmute。本函数只做「流级可入性」判定：BT 拒（A2DP 不能承载 DoP），
 * 非 ALSA（FILE/NULL）=纯透传管道允许。失败回退=报错关流（案 A：DSD 打不开/不支持→报错并关闭，绝不静默退化）。 */
static int dsd_enter(void)
{
    if (g_target == AUDIO_OUT_BT) {
        logmsg("dsd: enter rejected (BT/A2DP cannot carry DoP) -> close stream");
        return -1;
    }
    if (g_sink != SINK_ALSA) {
        logmsg("dsd: enter ok (sink=%d passthrough, no DOP_EN)", g_sink);
        g_dsd_active = 1;
        return 0;
    }
    g_dsd_active = 1;               /* 流级置位；DOP_EN 硬件时序由播放线程 reconfigure 执行 */
    logmsg("dsd: stream enters DoP DSD (DOP_EN sequenced on device reconfigure)");
    return 0;
}

static const char *port_name(int port)
{
    switch (port) {
    case 2: return "3.5 headset";
    case 3: return "4.4 balance";
    case 4: return "i2s/spdif digital";
    case 5: return "none(disable)";
    default: return "idle";
    }
}

/* 应用路由（numid=9）。port 0=idle；写后 cget 校验，失败记日志不重试风暴。
 * g_route_cur 为 plain int 松散写（路由线程不持 g_mu 调本函数——amixer popen 虽已有界，
 * 仍不该在持锁状态执行外部命令；int 写对 MIPS32 天然原子，竞争最坏是 QUERY 读到上一拍值）。 */
static void apply_route(int port)
{
    if (amixer_set(9, port, 1) < 0) {
        logmsg("route: amixer cset numid=9 %d exec failed", port);
        return;
    }
    int rb = amixer_get(9, 1);
    if (rb == port) logmsg("route: numid=9 -> %d (%s) ok", port, port_name(port));
    else            logmsg("route: verify failed (wanted %d got %d)", port, rb);
    g_route_cur = port;
}

/* 读 switch 文件（0/1 插孔态，-1 读失败） */
static int read_switch(const char *path)
{
    char buf[32];
    int fd = open(path, O_RDONLY);
    if (fd < 0) return -1;
    ssize_t n = read(fd, buf, sizeof buf - 1);
    close(fd);
    if (n <= 0) return -1;
    buf[n] = 0;
    return atoi(buf);
}

/* 路由评估（移植自 meow_route.c）：4.4 优先；都不插不动；写失败不重试风暴。
 * manual：调用方快照的 g_route_manual（本函数不持 g_mu、不读全局）。 */
static void route_evaluate(int manual, int *last_hb, int *last_bal, int *last_target)
{
    if (manual != -1) return;           /* 手动模式：不自动切 */
    int hb = read_switch("/sys/class/switch/headset/state");
    int bal = read_switch("/sys/class/switch/balance/state");
    if (hb < 0 || bal < 0) return;
    int prev_hb = *last_hb, prev_bal = *last_bal;
    *last_hb = hb; *last_bal = bal;
    int target;
    if (bal == 1)      target = 3;      /* 4.4 优先 */
    else if (hb == 1)  target = 2;
    else               target = 0;      /* 都不插：保持上次（0=不动？） 用 -1 表示不动 */
    if (bal == 0 && hb == 0) {
        if (prev_hb != hb || prev_bal != bal)
            logmsg("route: no jack (hs=%d bal=%d), keep last port", hb, bal);
        *last_target = -1;
        return;
    }
    int changed = (prev_hb != hb || prev_bal != bal);
    if (!changed && *last_target == target) return;
    int cur = amixer_get(9, 1);
    if (cur == target) { *last_target = target; if (changed) logmsg("route: %s already", port_name(target)); return; }
    logmsg("route: jack changed -> %s (wanted %d, was %d)", port_name(target), target, cur);
    apply_route(target);
    *last_target = target;
}

/* ---- settings.conf 写 audio.volume（同 launcher 同源同键） ---- */
static void settings_set_volume(int pct)
{
    FILE *f = fopen(g_settings_path, "r");
    char *data = NULL;
    size_t len = 0;
    if (f) {
        fseek(f, 0, SEEK_END);
        long sz = ftell(f);
        if (sz > 0 && sz < 64 * 1024) {
            fseek(f, 0, SEEK_SET);
            data = malloc((size_t)sz + 1);
            if (data) { len = fread(data, 1, (size_t)sz, f); data[len] = 0; }
        }
        fclose(f);
    }
    char val[16];
    snprintf(val, sizeof val, "%d", pct);
    char *out = malloc(len + 64);
    if (!out) { free(data); return; }
    out[0] = 0;
    size_t o = 0;
    int replaced = 0;
    if (data) {
        char *save = NULL;
        char *ln = strtok_r(data, "\n", &save);
        while (ln) {
            char *k = ln;
            while (*k == ' ' || *k == '\t') k++;
            int m = strncmp(k, "audio.volume", 12);
            if (m != 0) {
                int n = snprintf(out + o, len + 64 - o, "%s\n", ln);
                if (n > 0) o += (size_t)n;
            } else {
                int t = snprintf(out + o, len + 64 - o, "audio.volume = %s\n", val);
                if (t > 0) o += (size_t)t;
                replaced = 1;
            }
            ln = strtok_r(NULL, "\n", &save);
        }
        free(data);
    }
    if (!replaced) {
        int n = snprintf(out + o, len + 64 - o, "audio.volume = %s\n", val);
        if (n > 0) o += (size_t)n;
    }
    mkdir("/usr/data/meow", 0755);
    int fd = open(g_settings_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (fd >= 0) {
        /* 若原文件带 "# meow-settings 1" 头则保留——我们已被动保留了内容（含头）。
         * 无头（新文件）补一行头，符合 meow_settings 的解析预期。 */
        if (!replaced && o > 0) {
            /* 检查首行是否已含头 */
            int has_hdr = (strncmp(out, "# meow-settings", 15) == 0);
            if (!has_hdr) {
                char tmp[64];
                int hn = snprintf(tmp, sizeof tmp, "# meow-settings 1\n");
                if (write(fd, tmp, (size_t)hn) < 0) { }
            }
        }
        if (write(fd, out, o) < 0) { }
        close(fd);
    }
    free(out);
    logmsg("audio.volume persisted -> %d (%s)", pct, g_settings_path);
}

/* 通用设置读取：取 `key = value` 的 value（大小写不敏感前缀匹配；返回 0 找到，-1 未找到）。
 * line 缓冲内部复用；仅用于启动时一次性读取 output_bt/codec。 */
static int settings_get(const char *key, char *out, size_t n)
{
    FILE *f = fopen(g_settings_path, "r");
    if (!f) return -1;
    int rc = -1;
    char line[256];
    size_t klen = strlen(key);
    while (fgets(line, sizeof line, f)) {
        char *k = line;
        while (*k == ' ' || *k == '\t') k++;
        if (strncasecmp(k, key, klen) == 0) {
            char *eq = strchr(k, '=');
            if (eq) {
                const char *v = eq + 1;
                while (*v == ' ' || *v == '\t') v++;
                size_t o = 0;
                while (v[o] && v[o] != '\n' && v[o] != '\r' && o < n - 1) { out[o] = v[o]; o++; }
                out[o] = 0;
                rc = 0;
                break;
            }
        }
    }
    fclose(f);
    return rc;
}

/* P2 蓝牙：读 settings.conf `audio.output_bt`(0/1) → 输出目标（0=DAC 1=BT）。缺省 DAC。 */
static int settings_get_output_target(void)
{
    char buf[16];
    if (settings_get("audio.output_bt", buf, sizeof buf) == 0) {
        if (buf[0] == '1') return AUDIO_OUT_BT;
        if (buf[0] == '0') return AUDIO_OUT_DAC;
    }
    return AUDIO_OUT_DAC;
}

/* P2 蓝牙：读 settings.conf `bt.codec`（auto/SBC/AAC/aptX/LDAC…）→ g_bt_codec。缺省 auto。
 * codec 经 /usr/data/alsa.conf 的 `pcm.bluealsa` codec 参数生效（audiod BT 打开前 best-effort sync）。 */
static const char *settings_get_bt_codec(void)
{
    char buf[24];
    if (settings_get("bt.codec", buf, sizeof buf) == 0 && buf[0]) {
        snprintf(g_bt_codec, sizeof g_bt_codec, "%s", buf);
    } else {
        snprintf(g_bt_codec, sizeof g_bt_codec, "%s", BT_CODEC_AUTO);
    }
    return g_bt_codec;
}

static int settings_get_volume(void)
{
    FILE *f = fopen(g_settings_path, "r");
    if (!f) return g_vol_pct;
    char line[128];
    int v = g_vol_pct;
    while (fgets(line, sizeof line, f)) {
        char *k = line;
        while (*k == ' ' || *k == '\t') k++;
        if (strncmp(k, "audio.volume", 12) == 0) {
            char *eq = strchr(k, '=');
            if (eq) { v = atoi(eq + 1); break; }
        }
    }
    fclose(f);
    return v;
}

/* ============================================================================
 * 蓝牙 A2DP source（输出目标 OUT_BT，PLAN §三/§五）
 * ----------------------------------------------------------------------------
 * audiod **直接调用 libasound** 连 `pcm.bluealsa`（plug→bluealsa，播放向，A2DP），
 * 把播放器解码输出透传过去。BT 是**独立目标**：
 *   - 不开 hw:0,0（不 period=1024×4、不 FPGA numid=9 武装、不 DAC 音量反转）；
 *   - 保留音频流透传 + 格式归一（grant_fmt=S16，plug 层转 codec 协商率）；
 *   - 音量走 AVRCP/耳机侧（音量隔离：绝不下发 DAC numid=1/2 反转，见 vol_apply）。
 * 链接说明（2026-09-03 真机定案）：`pcm.bluealsa` 的 bluealsa 是**独立 pcm 插件**，libasound
 * 在运行时以 dlopen 加载 /usr/lib/alsa-lib/libasound_module_pcm_bluealsa.so（glibc，依赖
 * libdbus-1.so.3）——故 audiod 必须以**动态 glibc** 形态链接设备现有 libasound.so.2
 * （build_audiod.sh：zig --target=mipsel-linux-gnueabihf.2.22，删 -static）。musl-static 不可行
 * （实测 "Dynamic loading not supported"，无 dlopen 无法加载插件）；musl-dynamic 亦不可行（设备
 * 无 musl ld.so）。libasound 原型在此内联声明（避免依赖 asoundlib.h；工具链不提供）。
 * 禁止旁路：不跑 bluealsa-aplay/bluealsa-cli open（D-Bus/新建 daemon），audiod 内换目标 PCM 唯一最简。
 * ========================================================================== */
#define SND_PCM_STREAM_PLAYBACK      0
#define SND_PCM_ACCESS_RW_INTERLEAVED 3
#define SND_PCM_FORMAT_S16_LE        2
#define SND_PCM_NONBLOCK             1

/* libasound 相关函数原型（内联声明，避免依赖 asoundlib.h；snd_pcm_t 不透明 → void*） */
int  snd_pcm_open(void **pcm, const char *name, int stream, int mode);
int  snd_pcm_set_params(void *pcm, int format, int access, unsigned channels,
                        unsigned rate, int soft_resample, unsigned latency_us);
int  snd_pcm_nonblock(void *pcm, int nonblock);
long snd_pcm_writei(void *pcm, const void *buffer, unsigned long size);
int  snd_pcm_wait(void *pcm, int timeout);
int  snd_pcm_recover(void *pcm, int err, int silent);
int  snd_pcm_drain(void *pcm);
int  snd_pcm_close(void *pcm);
const char *snd_strerror(int errnum);

static void bt_close(void);     /* 前向：bt_write 判死路径要用 */
static void bt_vol_full(void);  /* 前向：bt_open 成功时促成 AVRCP 100% */

/* bt.codec 生效：bluealsa 的 codec 是 config-time 参数（/usr/data/alsa.conf `pcm.bluealsa` 块的
 * `codec "X"`）。audiod 在 BT 打开前做一次**幂等且外科式**的 token 替换：只把 bluealsa 块内的
 * `codec "..."` 改成 `codec "<g_bt_codec>"`（其余字符不动）。仅真机且文件可写时执行；
 * 宿主/只读/找不到 codec token → 跳过（绝不破坏 alsa.conf——audiod 只调整既有 token，不新建结构）。 */
static void bt_apply_codec_conf(void)
{
    if (!g_bt_codec[0] || !strcmp(g_bt_codec, BT_CODEC_AUTO) || !strcmp(g_bt_codec, "unchanged")) return;
    const char *path = "/usr/data/alsa.conf";
    /* 先探测是否已有 codec token：无则不动（避免误建/无权写） */
    {
        FILE *pf = fopen(path, "r");
        if (!pf) return;
        int hit = 0; char l[160];
        while (fgets(l, sizeof l, pf)) {
            char *k = l; while (*k==' '||*k=='\t') k++;
            if (strncmp(k, "codec", 5) == 0) { hit = 1; break; }
        }
        fclose(pf);
        if (!hit) return;
    }
    FILE *f = fopen(path, "r");
    if (!f) return;
    char *data = NULL; size_t len = 0;
    fseek(f, 0, SEEK_END); long sz = ftell(f);
    if (sz <= 0 || sz > 64 * 1024) { fclose(f); return; }
    fseek(f, 0, SEEK_SET);
    data = malloc((size_t)sz + 1);
    if (!data) { fclose(f); return; }
    len = fread(data, 1, (size_t)sz, f); data[len] = 0;
    fclose(f);
    char *out = malloc(len + 64);
    if (!out) { free(data); return; }
    out[0] = 0; size_t o = 0; int changed = 0;
    char *save = NULL;
    char *ln = strtok_r(data, "\n", &save);
    while (ln) {
        char *k = ln; while (*k==' '||*k=='\t') k++;
        int is_codec = (strncmp(k, "codec", 5) == 0);
        if (is_codec && !changed) {
            int n = snprintf(out + o, len + 64 - o, "codec \"%s\"\n", g_bt_codec);
            if (n > 0) o += (size_t)n;
            changed = 1;
        } else {
            int n = snprintf(out + o, len + 64 - o, "%s\n", ln);
            if (n > 0) o += (size_t)n;
        }
        ln = strtok_r(NULL, "\n", &save);
    }
    free(data);
    if (changed) {
        int fd = open(path, O_WRONLY | O_TRUNC, 0644);
        if (fd >= 0) { if (write(fd, out, o) < 0) { } close(fd); logmsg("bt: codec conf %s -> %s", path, g_bt_codec); }
        else logmsg("bt: codec conf %s not writable, skip", path);
    }
    free(out);
}

/* P2 BT DEV 自识别：把 /usr/data/alsa.conf 的 `pcm.bluealsa` DEV/device 自动改为**当前连接的
 * A2DP sink 设备** MAC（bluealsa-cli list-pcms 的 a2dpsrc 端点）。幂等（设备未变不重写）、
 * 无设备/失败跳过；只改 DEV/device 两处、保留 codec/其余 token。BT 打开前调用，实现
 * 「连哪个设备就播哪个」。跟 bt_apply_codec_conf 同构（外科式 token 替换，绝不建结构）。 */
static void bt_apply_device_conf(void)
{
    char mac[32] = "";
    char *o = popen_read_tmo(1500, "bluealsa-cli list-pcms 2>/dev/null");
    if (!o) { logmsg("bt: dev conf skipped (no bluealsa-cli)"); return; }
    if (bt_dev_detect_mac(o, mac, sizeof mac) != 0) {
        logmsg("bt: dev conf skipped (no a2dpsrc pcm)");
        return;
    }
    logmsg("bt: current a2dp dev %s", mac);
    const char *path = "/usr/data/alsa.conf";
    FILE *f = fopen(path, "r");
    if (!f) return;
    fseek(f, 0, SEEK_END); long sz = ftell(f);
    if (sz <= 0 || sz > 64 * 1024) { fclose(f); return; }
    fseek(f, 0, SEEK_SET);
    char *data = malloc((size_t)sz + 1);
    if (!data) { fclose(f); return; }
    size_t rl = fread(data, 1, (size_t)sz, f); data[rl] = 0;
    fclose(f);
    char *outdata = NULL; size_t outlen = 0;
    int rc = bt_dev_rewrite(data, rl, mac, &outdata, &outlen);
    free(data);
    if (rc == 0) {
        int fd = open(path, O_WRONLY | O_TRUNC, 0644);
        if (fd >= 0) {
            if (write(fd, outdata, outlen) < 0) { }
            close(fd);
            logmsg("bt: dev conf auto-updated %s -> %s", path, mac);
        } else {
            logmsg("bt: dev conf %s not writable, skip", path);
        }
    } else if (rc == 1) {
        logmsg("bt: dev conf ok (already %s)", mac);
    } else {
        logmsg("bt: dev conf skip (no pcm.bluealsa/no DEV token)");
    }
    if (outdata) free(outdata);
}

/* BT 打开：libasound → snd_pcm_open(pcm.bluealsa/bluealsa, PLAYBACK, NONBLOCK) →
 * set_params(S16_LE, RW, ch, rate, soft_resample, 100ms)。返回 0=ok。失败置 g_bt_open=0。 */
static int bt_open(void)
{
    void *pcm = NULL;
    const char *names[2] = { BT_PCM_DEFAULT, BT_PCM_FALLBACK };
    int r = -1;
    for (int i = 0; i < 2; i++) {
        r = snd_pcm_open(&pcm, names[i], SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
        if (r == 0) { logmsg("bt: opened %s", names[i]); break; }
        logmsg("bt: snd_pcm_open %s: %s", names[i], snd_strerror(r));
        pcm = NULL;
    }
    if (r != 0) return -1;
    g_bt_hdl = pcm;
    snd_pcm_nonblock(pcm, 1);
    unsigned rate = g_st.rate ? g_st.rate : 44100;
    unsigned ch   = g_st.ch ? g_st.ch : 2;
    r = snd_pcm_set_params(pcm, SND_PCM_FORMAT_S16_LE, SND_PCM_ACCESS_RW_INTERLEAVED,
                           ch, rate, 1, 100000);
    if (r < 0) {
        logmsg("bt: set_params %u/%u/S16: %s", rate, ch, snd_strerror(r));
        snd_pcm_close(pcm); g_bt_hdl = NULL; return -1;
    }
    g_bt_open = 1;
    logmsg("bt: PCM ready rate=%u ch=%u fmt=S16 codec=%s", rate, ch, g_bt_codec);
    bt_vol_full();                  /* best-effort AVRCP 100%（一次性；失败仅日志） */
    return 0;
}

/* BT 写：非阻塞 writei + wait 超时（镜像 DAC O_NONBLOCK+poll 护栏），xrun recover。
 * 设备停摆/无连接 → 丢帧（g_played_frames 照记），绝不把播放线程永久压进 libasound。 */
static void bt_write(uint8_t *buf, size_t n)
{
    if (!g_bt_open || !g_bt_hdl) {
        static unsigned s_drop = 0;
        if ((s_drop++ % 256) == 0)
            logmsg("bt_write dropped %zu bytes (bt not open, x%u)", n, s_drop);
        g_played_frames += n / (size_t)frame_size();
        return;
    }
    size_t fs = (size_t)frame_size();
    if (!fs) return;
    unsigned long left = (unsigned long)(n / fs);
    if (!left) return;
    const uint8_t *off = buf;
    int stalls = 0;
    while (left > 0 && !g_stop) {
        long w = snd_pcm_writei(g_bt_hdl, off, left);
        if (w > 0) { off += (size_t)w * fs; left -= (unsigned long)w; stalls = 0; continue; }
        if (w < 0) {
            int err = (int)(-w);
            if (err == EAGAIN || err == EWOULDBLOCK) {
                int pr = snd_pcm_wait(g_bt_hdl, ALSA_POLL_MS);
                if (pr == 0) {          /* 无空间超时 → 停摆计数（镜像 DAC stall） */
                    g_stall++; stalls++;
                    if (stalls >= ALSA_STALL_MAX) {
                        logmsg("bt WEDGED: %d consecutive waits, close + drop until next OPEN", stalls);
                        bt_close(); g_bt_open = 0; g_dev_open = 0;
                        g_played_frames += n / fs; return;
                    }
                    continue;
                }
                if (pr < 0 && errno != EINTR) { logmsg("bt wait err: %s", strerror(errno)); break; }
                continue;
            }
            if (err == EPIPE || err == ESTRPIPE) {   /* xrun：recover 后继续 */
                g_underrun++;
                logmsg("bt xrun #%u -> recover", (unsigned)g_underrun);
                snd_pcm_recover(g_bt_hdl, err, 1);
                continue;
            }
            logmsg("bt writei err: %s", snd_strerror(err));
            break;
        }
        if (w == 0) break;
    }
    unsigned long done = (unsigned long)(n / fs) - left;
    g_played_frames += done;
}

static void bt_close(void)
{
    if (g_bt_hdl) {
        snd_pcm_drain(g_bt_hdl);
        snd_pcm_close(g_bt_hdl);
        g_bt_hdl = NULL;
    }
    g_bt_open = 0;
}

/* 音量隔离（PLAN §五）：路由=BT 时**不下发 DAC 音量反转**（音量由 AVRCP/耳机侧控）。
 * 仅记录 DAC 音量（g_vol_pct 语义=本地 DAC 音量）；BT 侧 best-effort 促成 AVRCP 100%
 * （避免"窃听音量误解"——耳机侧音量钉到最响，设备侧滑块即绝对控制）。 */
static void bt_vol_full(void)
{
    if (g_bt_vol_full_done) return;
    g_bt_vol_full_done = 1;
    char *o = popen_read_tmo(1500, "bluealsa-cli list-pcms 2>/dev/null");
    if (!o) { logmsg("bt: avrcp set-100 skipped (no bluealsa-cli)"); return; }
    char pcm[128] = "";
    const char *ln = o;
    while (ln && *ln) {
        const char *nl = strchr(ln, '\n');
        const char *p = ln;
        while (*p == ' ' || *p == '\t') p++;
        if (strstr(p, "a2dpsrc") || strstr(p, "a2dp_source")) {
            const char *tok = p;
            while (*tok && *tok != ' ' && *tok != '\t') tok++;
            size_t tlen = (size_t)(tok - p);
            if (tlen && tlen < sizeof pcm) { memcpy(pcm, p, tlen); pcm[tlen] = 0; }
            break;
        }
        if (!nl) break;
        ln = nl + 1;
    }
    if (!pcm[0]) { logmsg("bt: avrcp set-100 skipped (no a2dpsrc pcm found)"); return; }
    char cmd[256];
    snprintf(cmd, sizeof cmd, "%s volume %s 100 >/dev/null 2>&1", BT_VOL_FULL_PCM, pcm);
    char *r = popen_read_tmo(1500, cmd);
    logmsg("bt: avrcp volume set 100%% (%s)%s", pcm, r ? " ok" : " (exec failed; AVRCP still controls)");
}

/* 音量应用（含 BT 隔离）：BT → 只通知 AVRCP（best-effort），绝不动 DAC numid=1/2、不持久化
 * audio.volume（那是 DAC 音量键）；DAC → 原感知锥度反转 + 持久化。 */
static void vol_apply(int pct)
{
    if (pct < 0) pct = 0;
    if (pct > 100) pct = 100;
    if (g_target == AUDIO_OUT_BT) {
        logmsg("vol -> %d%% (BT/AVRCP, DAC numid=1/2 NOT written)", pct);
        return;
    }
    g_vol_pct = pct;
    dac_vol_set(pct);
    settings_set_volume(pct);
}

/* 输出目标切换（g_mu 已持）。target 改变 → 有流则标重配（重启 PCM 到新目标）。 */
static void target_set(int target)
{
    if (target != AUDIO_OUT_DAC && target != AUDIO_OUT_BT) {
        logmsg("output: invalid target %d", target); return;
    }
    if (g_target == target) { logmsg("output: target already %d", target); return; }
    logmsg("output: target %d -> %d (%s)", g_target, target, target == AUDIO_OUT_BT ? "BT" : "DAC");
    g_target = target;
    if (g_st.active) g_reconfig_pending = 1;
    pthread_cond_signal(&g_cond);
}

/* ---- ALSA UAPI ---- */
#ifdef AUDIOD_HAVE_ALSA
static void pmask(struct snd_mask *m, unsigned bit) { m->bits[bit / 32] |= 1u << (bit % 32); }
static void pivset(struct snd_interval *iv, unsigned val)
{
    iv->min = iv->max = val;
    iv->integer = 1;
    iv->openmin = iv->openmax = 0;
    iv->empty = 0;
}
/* 初始化为「全放行」（libasound snd_pcm_hw_params_any 语义）：所有 mask 全 1、所有 interval
 * [0, UINT_MAX]。**必须**：memset 0 的 interval（min=max=0）等价于「只能取 0」，内核 refine
 * 与设备真实约束求交必为空 → HW_PARAMS 恒 EINVAL（真机踩过，agent-244 probe_alsa 全灭定位）。 */
static void alsa_params_any(struct snd_pcm_hw_params *p)
{
    memset(p, 0, sizeof *p);
    unsigned nm = SNDRV_PCM_HW_PARAM_LAST_MASK - SNDRV_PCM_HW_PARAM_FIRST_MASK + 1;
    for (unsigned i = 0; i < nm; i++)
        for (unsigned b = 0; b < sizeof p->masks[i].bits / sizeof p->masks[i].bits[0]; b++)
            p->masks[i].bits[b] = ~0u;
    unsigned ni = SNDRV_PCM_HW_PARAM_LAST_INTERVAL - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL + 1;
    for (unsigned i = 0; i < ni; i++) {
        p->intervals[i].min = 0;
        p->intervals[i].max = ~0u;
    }
}
static int alsa_hw_params(int fd, unsigned rate, unsigned ch, unsigned fmt)
{
    struct snd_pcm_hw_params p;
    alsa_params_any(&p);
    p.flags = 0;
    /* mask 必须「先清零再单点」：params_any 已把 mask 置全 1，pmask 只 OR 不清位——
     * 若 access 留全 1，内核 choose 取最低 bit=MMAP_INTERLEAVED，runtime->access≠RW_INTERLEAVED
     * → 之后 write() 恒 EINVAL（真机踩过第二坑；libasound 靠 plug 层自动转 mmap 掩盖了它）。 */
    struct snd_mask *am = &p.masks[SNDRV_PCM_HW_PARAM_ACCESS - SNDRV_PCM_HW_PARAM_FIRST_MASK];
    memset(am, 0, sizeof *am); pmask(am, SNDRV_PCM_ACCESS_RW_INTERLEAVED);
    struct snd_mask *fm = &p.masks[SNDRV_PCM_HW_PARAM_FORMAT - SNDRV_PCM_HW_PARAM_FIRST_MASK];
    memset(fm, 0, sizeof *fm); pmask(fm, fmt);
    struct snd_mask *sm = &p.masks[SNDRV_PCM_HW_PARAM_SUBFORMAT - SNDRV_PCM_HW_PARAM_FIRST_MASK];
    memset(sm, 0, sizeof *sm); pmask(sm, SNDRV_PCM_SUBFORMAT_STD);
    pivset(&p.intervals[SNDRV_PCM_HW_PARAM_CHANNELS - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL], ch);
    pivset(&p.intervals[SNDRV_PCM_HW_PARAM_RATE - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL], rate);
    /* M2.94 长流停摆根治（真机实证 60s 零 stall）：显式收窄周期几何到 tiny_alsa 惯例
     * period=1024 frames × 4。否则驱动默认 buffer 巨大（上限 1048576 帧 ≈23s），
     * hbc3000 桥靠周期中断驱动，中断稀缺 → 桥时钟域 wedge → 播 12s 左右停摆。
     * （tonepcm2 几何矩阵实测：1024×4 连续 60s 实时消费零 stall。） */
    pivset(&p.intervals[SNDRV_PCM_HW_PARAM_PERIOD_SIZE - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL], 1024);
    pivset(&p.intervals[SNDRV_PCM_HW_PARAM_PERIODS - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL], 4);
    p.rmask = ~0u; p.info = 0; p.msbits = 0; p.rate_num = 0; p.rate_den = 0;
    return ioctl(fd, SNDRV_PCM_IOCTL_HW_PARAMS, &p);
}
#endif

static int alsa_fmt_to_snd(int fmt)
{
    switch (fmt) {
    case AUDIO_FMT_S16: return SNDRV_PCM_FORMAT_S16_LE;
    case AUDIO_FMT_S24: return SNDRV_PCM_FORMAT_S24_LE;
    case AUDIO_FMT_S32: return SNDRV_PCM_FORMAT_S32_LE;
    case AUDIO_FMT_DOP: return SNDRV_PCM_FORMAT_S32_LE;   /* DoP 走 32-bit 容器（16bit DSD + 标记 + 0） */
    case AUDIO_FMT_FLOAT: return SNDRV_PCM_FORMAT_FLOAT_LE;
    default: return SNDRV_PCM_FORMAT_S16_LE;
    }
}

/* 探测硬件最优格式（设备空闲时调用；缓存 g_hw_fmt）。返回 0=确定，-1=无法探测。
 * A3（24/32bit 高清流）：**偏好 S32**——CS43198 为 32bit DAC，S32 可顺带把 16bit 内容做无损升位、
 * 24/32bit 直通不降位（plan §一「S16 直通/S32 升位」）。按高清率优先探测 S32（192k→176.4k→44.1k），
 * 全失败再退 S16。旧实现只在 44.1k 试 S16 并**立即返回**（永远拿不到 S32，高清降位）。
 * ⚠️ 探测只 open+hw_params（非 start），与 FPGA 武装无关；真机此路径仍需 AUDIO 实测复核。 */
static int hw_probe(void)
{
    if (g_sink != SINK_ALSA) { g_hw_fmt = AUDIO_FMT_S16; g_hw_probed = 1; return 0; }
    if (g_hw_probed) return 0;
#ifdef AUDIOD_HAVE_ALSA
    static const unsigned rates[3] = { 192000u, 176400u, 44100u };
    for (int r = 0; r < 3 && !g_hw_probed; r++) {
        int fd = open(DEV_PCM, O_RDWR | O_NONBLOCK);
        if (fd >= 0) {
            if (alsa_hw_params(fd, rates[r], 2, SNDRV_PCM_FORMAT_S32_LE) == 0)
                { g_hw_fmt = AUDIO_FMT_S32; g_hw_probed = 1; }
            close(fd);
        }
    }
    for (int r = 0; r < 3 && !g_hw_probed; r++) {
        int fd = open(DEV_PCM, O_RDWR | O_NONBLOCK);
        if (fd >= 0) {
            if (alsa_hw_params(fd, rates[r], 2, SNDRV_PCM_FORMAT_S16_LE) == 0)
                { g_hw_fmt = AUDIO_FMT_S16; g_hw_probed = 1; }
            close(fd);
        }
    }
#endif
    if (!g_hw_probed) { g_hw_fmt = AUDIO_FMT_S16; g_hw_probed = 1; }
    logmsg("hw probe: optimal fmt=%s", fmt_name(g_hw_fmt));
    return 0;
}

/* ---- FILE/NULL sink ---- */
static void wav_header(int fd, int rate, int ch, int bits, uint32_t data_len)
{
    unsigned char h[44];
    memset(h, 0, sizeof h);
    memcpy(h + 0, "RIFF", 4);
    uint32_t le = 36 + data_len; memcpy(h + 4, &le, 4);
    memcpy(h + 8, "WAVE", 4);
    memcpy(h + 12, "fmt ", 4);
    le = 16; memcpy(h + 16, &le, 4);
    uint16_t s16 = 1; memcpy(h + 20, &s16, 2);
    s16 = (uint16_t)ch; memcpy(h + 22, &s16, 2);
    le = (uint32_t)rate; memcpy(h + 24, &le, 4);
    le = (uint32_t)(rate * ch * bits / 8); memcpy(h + 28, &le, 4);
    s16 = (uint16_t)(ch * bits / 8); memcpy(h + 32, &s16, 2);
    s16 = (uint16_t)bits; memcpy(h + 34, &s16, 2);
    memcpy(h + 36, "data", 4);
    le = data_len; memcpy(h + 40, &le, 4);
    if (write(fd, h, 44) != 44) { }
}

/* ---- 播放线程设备管理（dev_open/close/write 皆在播放线程调用） ---- */
static void dev_close(void);    /* 前向：dev_write 的 wedge 判死路径要用 */

static int dev_open(void)
{
    /* 输出目标=BT 且走真机 ALSA：打开 libasound 的 pcm.bluealsa（不开 hw:0,0）。
     * 宿主即 FILE/NULL sink 时不走此支——因此宿主可测「目标选择/音量隔离/格式归一」逻辑，
     * 真实 bluealsa 传输留给真机（见 bt_* 注释）。失败 → 降级丢帧（自感知兜底 §五）。 */
    if (g_target == AUDIO_OUT_BT && g_sink == SINK_ALSA) {
        bt_apply_device_conf();   /* P2：DEV 幂等自更新到当前连接 A2DP 设备（连哪台播哪台） */
        bt_apply_codec_conf();
        if (bt_open() == 0) return 0;      /* g_bt_open=1；返回 0=逻辑已开（真实句柄在 g_bt_hdl） */
        logmsg("bt: open failed (degrade: drop PCM until next OPEN)");
        return -1;
    }
    uint32_t rate = g_st.rate, ch = g_st.ch, fmt = g_st.fmt;
    int bits = fmt_bps((int)fmt) * 8;
    if (g_sink == SINK_ALSA) {
#ifdef AUDIOD_HAVE_ALSA
        /* O_NONBLOCK：写路径走 poll(POLLOUT)+限时（dev_write），write 本身永不睡眠——
         * 驱动 wedge 时绝不能把播放线程永久压进内核（真机长流卡死根因防线）。 */
        int fd = open(DEV_PCM, O_RDWR | O_NONBLOCK);
        if (fd < 0) { logmsg("dev open %s: %s", DEV_PCM, strerror(errno)); return -1; }
        if (alsa_hw_params(fd, rate, ch, alsa_fmt_to_snd((int)fmt)) != 0) {
            logmsg("dev hw_params %u/%u/%s failed", (unsigned)rate, (unsigned)ch, fmt_name((int)fmt));
            close(fd);
            return -1;
        }
        ioctl(fd, SNDRV_PCM_IOCTL_PREPARE, 0);
        return fd;
#else
        return -1;
#endif
    }
    if (g_sink == SINK_FILE) {
        int fd = open(g_out_wav, O_WRONLY | O_CREAT | O_TRUNC, 0644);
        if (fd < 0) { logmsg("dev open wav %s: %s", g_out_wav, strerror(errno)); return -1; }
        wav_header(fd, (int)rate, (int)ch, bits, 0);
        return fd;
    }
    return -2;   /* NULL sink */
}

static void dev_write(uint8_t *buf, size_t n)
{
    /* 测试钩子（仅 env 开启）：写延迟（模拟慢设备/实时 pacing）与 wedge（模拟驱动卡死——
     * 睡到 g_stop，复现真机「播放线程永不返回」故障注入，验证 IO 线程/ring 不死锁）。 */
    if (g_test_write_delay_ms > 0) {
        struct timespec ts = { g_test_write_delay_ms / 1000, (long)(g_test_write_delay_ms % 1000) * 1000000L };
        nanosleep(&ts, NULL);
    }
    if (g_test_wedge_after >= 0) {
        if (g_dev_bytes >= (uint64_t)g_test_wedge_after) {
            static int s_wedged = 0;
            if (!s_wedged) { s_wedged = 1; logmsg("TEST: device wedged (simulated after %llu bytes)", (unsigned long long)g_dev_bytes); }
            while (!g_stop) {
                struct timespec ts = { 0, 100 * 1000000L };
                nanosleep(&ts, NULL);
            }
            return;
        }
        g_dev_bytes += n;
    }
    if (g_target == AUDIO_OUT_BT && g_sink == SINK_ALSA) { bt_write(buf, n); return; }
    if (g_sink == SINK_NULL) { g_played_frames += n / (size_t)frame_size(); return; }
    if (g_sink == SINK_ALSA) {
#ifdef AUDIOD_HAVE_ALSA
        if (g_dev_fd < 0) {
            /* 设备开失败（hw_params 拒/无卡/wedge 后被判死）：丢弃 PCM 防 ring 堵死 + 背压卡死客户端；
             * 日志限频（每 256 次一记），避免 write(-1) 错误风暴（真机踩过）。 */
            static unsigned s_drop = 0;
            if ((s_drop++ % 256) == 0)
                logmsg("dev_write dropped %zu bytes (device not open, x%u)", n, s_drop);
            g_played_frames += n / (size_t)frame_size();
            return;
        }
        /* O_NONBLOCK + poll(POLLOUT) 模式：写前等可写（上限 ALSA_POLL_MS）。
         * 连续 ALSA_STALL_MAX 次超时 = 设备停摆（驱动 wedge 特征）→ PREPARE 自救仍无效
         * 则关卡进入丢弃模式（g_dev_open=0），下一路 OPEN 重开重试——播放线程绝不永久
         * 堵在内核 write 里（真机长流卡死的级联源头）。 */
        int stalls = 0;
        size_t off = 0;
        while (off < n) {
            if (g_stop) break;
            struct pollfd pf;
            pf.fd = g_dev_fd; pf.events = POLLOUT; pf.revents = 0;
            int pr = poll(&pf, 1, ALSA_POLL_MS);
            if (pr == 0) {
                g_stall++;
                stalls++;
                logmsg("alsa stall #%u (poll %dms no space, xrun-ish) -> PREPARE",
                       (unsigned)g_stall, ALSA_POLL_MS);
                ioctl(g_dev_fd, SNDRV_PCM_IOCTL_PREPARE, 0);
                if (stalls >= ALSA_STALL_MAX) {
                    logmsg("alsa WEDGED: %d consecutive stalls, close device + drop PCM until next OPEN", stalls);
                    dev_close();
                    return;
                }
                continue;
            }
            if (pr < 0) { if (errno == EINTR) continue; logmsg("alsa poll err: %s", strerror(errno)); break; }
            ssize_t w = write(g_dev_fd, buf + off, n - off);
            if (w > 0) { off += (size_t)w; stalls = 0; continue; }
            if (w < 0) {
                if (errno == EINTR || errno == EAGAIN) continue;
                if (errno == EPIPE) {   /* xrun：重备 + 恢复（设计 §2） */
                    g_underrun++;
                    logmsg("xrun #%u -> PREPARE", (unsigned)g_underrun);
                    ioctl(g_dev_fd, SNDRV_PCM_IOCTL_PREPARE, 0);
                    continue;
                }
                logmsg("alsa write err: %s", strerror(errno));
                break;
            }
            break;
        }
        size_t done = (off / (size_t)frame_size()) * (size_t)frame_size();
        g_played_frames += done / (size_t)frame_size();
#endif
        return;
    }
    if (g_sink == SINK_FILE) {
        if (write(g_dev_fd, buf, n) > 0)
            g_played_frames += n / (size_t)frame_size();
    }
}

static void dev_close(void)
{
    if (g_bt_open) { bt_close(); g_dev_fd = -1; g_dev_open = 0; return; }
    if (g_sink == SINK_FILE && g_dev_fd >= 0 && g_dev_fd != -2) {
        off_t end = lseek(g_dev_fd, 0, SEEK_END);
        if (end > 44) {
            uint32_t data_len = (uint32_t)(end - 44);
            lseek(g_dev_fd, 4, SEEK_SET);         /* RIFF 总长（36 + data） */
            uint32_t le = 36 + data_len; if (write(g_dev_fd, &le, 4) != 4) { }
            lseek(g_dev_fd, 40, SEEK_SET);        /* data 块长（rate/ch/bits 头已由 wav_header 写入） */
            if (write(g_dev_fd, &data_len, 4) != 4) { }
        }
        close(g_dev_fd);
    } else if (g_dev_fd >= 0 && g_dev_fd != -2) {
        close(g_dev_fd);
    }
    g_dev_fd = -1;
    g_dev_open = 0;
}

/* 播放线程：处理一次重配（静音 → 关旧 → 开新 → 复原）。调用方已持 g_mu。
 * DSD（audiod 只透传）：DoP 时序「mute(PCM+DSD) → DOP_EN=1 → hw_params(容器率) → DSD_VOLUME → unmute」。
 * DOP_EN 必须早于 dev_open 的 hw_params（plan §三），离开 DSD 时 DOP_EN=0 须早于关设备。 */
static void reconfigure_locked(void)
{
    uint32_t rate = g_st.rate, ch = g_st.ch, fmt = g_st.fmt;
    const char *tgt = (g_target == AUDIO_OUT_BT) ? "bt" : "dac";
    logmsg("reconfigure device: %u/%u/%s target=%s", (unsigned)rate, (unsigned)ch, fmt_name((int)fmt), tgt);
    int saved_vol = g_vol_pct;
    int new_dsd = (fmt == AUDIO_FMT_DOP);
    int do_dsd_seq = (g_target == AUDIO_OUT_DAC && g_sink == SINK_ALSA);   /* DOP_EN 仅 DAC 物理路径 */
    if (do_dsd_seq) {
        if (new_dsd) {
            dac_vol_mute();                                     /* ① mute（PCM+DSD 双组） */
            /* ② DOP_EN 写后校验：**DSD 打不开/不支持→报错关流（案 A，不静默退化）**——DOP_EN 未确认
             * 为 1 则丢弃本流（active=0→播放线程不再喂 DAC），客户端经 STATE active=0 感知并重开/换目标。 */
            if (amixer_set(DOP_EN_NUMID, 1, 1) < 0 || amixer_get(DOP_EN_NUMID, 1) != 1) {
                logmsg("dsd: DOP_EN (numid=%d) not confirmed -> close stream (no silent degrade)", DOP_EN_NUMID);
                dac_vol_mute();
                amixer_set(DOP_EN_NUMID, 0, 1);   /* 确保离开 DOP（兼容旧 DSD 设备残留） */
                session_end_locked();
                g_dev_dsd = 0;
                g_reconfig_pending = 0;
                return;
            }
            logmsg("dsd: DOP_EN -> 1 (DoP container)");
        } else if (g_dev_dsd) {
            logmsg("dsd: DOP_EN -> 0 (leave DoP)");             /* 离开 DSD：DOP_EN=0 后关设备 */
            amixer_set(DOP_EN_NUMID, 0, 1);
        }
    }
    dev_close();
    g_dev_fd = dev_open();
    if (g_dev_fd >= 0 || (g_sink == SINK_NULL && g_dev_fd == -2)) {
        g_dev_open = 1;
        g_dev_rate = rate; g_dev_ch = ch; g_dev_fmt = fmt;
        if (g_dev_fd == -2) g_dev_fd = -1;       /* NULL sink：无真实 fd */
        g_dev_dsd = (do_dsd_seq && new_dsd);
        if (g_target == AUDIO_OUT_DAC && g_sink == SINK_ALSA) dac_vol_set(saved_vol);  /* 复原（含 DSD_VOLUME） */
        logmsg("device open ok: %u/%u/%s sink=%d target=%s%s", (unsigned)rate, (unsigned)ch,
               fmt_name((int)fmt), g_sink, tgt, g_dev_dsd ? " dsd" : "");
    } else {
        logmsg("device open FAILED !!");
        g_dev_dsd = 0;
    }
    g_reconfig_pending = 0;
}

/* 播放线程主体。
 * 语义：只有当前授权流（g_st.active）喂 DAC；暂停时不读 ring（保留已缓冲）；
 * 停止/EOF 时不丢尾——先排空 ring 再关设备（否则 tone 末尾/缓冲尾被截断）。
 * 所有等待为 COND_WAIT_MS 周期 timedwait：丢失唤醒最多迟 1s 自愈，SIGTERM 也能及时退。 */
static void *playback_thread(void *arg)
{
    (void)arg;
    static uint8_t buf[READ_CHUNK];
    for (;;) {
        g_hb_play++;
        int have = 0;
        pthread_mutex_lock(&g_mu);
        for (;;) {
            g_hb_play++;
            if (g_stop) { have = -1; break; }
            int fs = frame_size();
            if (fs <= 0) { cond_wait_tmo(COND_WAIT_MS); continue; }  /* 无流 param → 等 */
            if (g_reconfig_pending) { have = 1; break; } /* 重配 */
            int draining = !g_st.active;
            int paused = g_st.active && g_paused;
            size_t av = ring_bytes();
            if ((draining && av < (size_t)fs) || paused) {
                /* 排空完毕（或暂停）：若设备仍开且已排空 → 关；否则等待 */
                if (draining && g_dev_open) dev_close();
                if (draining && g_dev_dsd && g_sink == SINK_ALSA && g_target == AUDIO_OUT_DAC) {
                    logmsg("dsd: DOP_EN -> 0 (stream drained)");
                    amixer_set(DOP_EN_NUMID, 0, 1);
                    g_dev_dsd = 0;
                }
                if (draining) session_clean_locked();  /* 流已死且排空完成：会话统计彻底归零 */
                cond_wait_tmo(COND_WAIT_MS);
                continue;
            }
            if (draining || av >= (size_t)fs) { have = 2; break; } /* 有数据可读（或排空态） */
            cond_wait_tmo(COND_WAIT_MS);
        }
        if (have == -1) { pthread_mutex_unlock(&g_mu); break; }
        if (have == 1) { reconfigure_locked(); pthread_mutex_unlock(&g_mu); continue; }
        if (have == 0) { if (g_dev_open) dev_close(); pthread_mutex_unlock(&g_mu); continue; }
        size_t want = READ_CHUNK;
        size_t fs = (size_t)frame_size();
        if (fs > 0) want = (want / fs) * fs;
        size_t n = ring_read_locked(buf, want);
        if (n) meter_feed(buf, n);      /* 电平表：整数累加，窗口到点才结算 */
        pthread_mutex_unlock(&g_mu);
        if (n == 0) continue;
        dev_write(buf, n);
    }
    pthread_mutex_lock(&g_mu);
    if (g_dev_open) dev_close();
    pthread_mutex_unlock(&g_mu);
    return NULL;
}

/* ---- 客户端管理 ---- */
static struct client *cli_by_fd(int fd)
{
    for (int i = 0; i < CLI_MAX; i++)
        if (g_cli[i].used && g_cli[i].fd == fd) return &g_cli[i];
    return NULL;
}
static struct client *cli_alloc(int fd)
{
    struct client *freec = NULL;
    for (int i = 0; i < CLI_MAX; i++) {
        if (g_cli[i].used) continue;
        freec = &g_cli[i];
        break;
    }
    if (!freec) return NULL;
    memset(freec, 0, sizeof *freec);
    freec->used = 1;
    freec->fd = fd;
    freec->state = CLS_OPEN;
    freec->sid = 0;
    return freec;
}
static void cli_free(struct client *c)
{
    if (!c || !c->used) return;
    if (c->fd >= 0) close(c->fd);
    c->used = 0;
    c->fd = -1;
    if (g_st.active && g_st.sid == c->sid) {
        logmsg("client EOF: stream %u recycled (app=%s)", (unsigned)c->sid, g_st.app_id);
        session_end_locked();
    }
}
/* ---- 流结束/会话回收（客户端死亡或显式 STOP 后，STATE 须回到干净无流基线） ----
 * 两段式：
 *  - session_end_locked()：流结束标记（停止/EOF 即时调用）。置 inactive + 清会话身份
 *    （sid/app_id）+ 唤醒播放线程排空 ring。**不清空 ring、不清 rate/ch/fmt**：未播完的缓冲
 *    要写完（排空）才关设备，否则 tone/播放末尾被截断；排空期间 frame_size() 仍依赖 rate/ch/fmt。
 *    ring 的重置只发生在 OPEN 授予新流时（ring_rebuild）。
 *  - session_clean_locked()：会话统计彻底清零（流已结束且 ring 排空完毕的迟后调用）——
 *    STATE 归零：rate/ch/fmt=0、written=played=0、underrun/drop/stall=0、rms/peak=-inf、lvlseq=0。
 *    此刻 rate/ch/fmt 已不再被排空引用，可安全清零。txdrop 为全局客户端级（不随流清），不动。 */
static void session_end_locked(void)
{
    g_st.active = 0;
    g_st.sid = 0;
    g_st.app_id[0] = 0;
    g_paused = 0;
    g_reconfig_pending = 0;
    pthread_cond_signal(&g_cond);
}
static void session_clean_locked(void)
{
    g_st.rate = 0;
    g_st.ch = 0;
    g_st.fmt = 0;
    g_dsd_active = 0;            /* 流级 DSD 位归零（DOP_EN 设备位由 drain/reconfigure 时序负责） */
    g_dev_dsd = 0;
    g_written_frames = 0;
    g_played_frames = 0;
    g_underrun = 0;
    g_drop_frames = 0;
    g_stall = 0;
    g_m_sumsq = 0;
    g_m_peak = 0;
    g_m_frames = 0;
    g_m_win = 0;
    g_lvl_rms_db10 = g_lvl_peak_db10 = METER_FLOOR_DB10;
    g_lvl_seq = 0;
}

/* 处理一个客户端帧（调用方已持 g_mu） */
static void dispatch(struct client *c, uint16_t type, uint32_t req_id, const uint8_t *pl, uint32_t len)
{
    switch (type) {
    case MSG_AUDIO_OPEN: {
        if (len < sizeof(m_audio_open_t)) { m_audio_open_ack_t a; memset(&a, 0, sizeof a); a.err = MEOW_ERR_INVAL; send_frame(c->fd, MSG_AUDIO_OPEN_ACK, req_id, &a, sizeof a); return; }
        m_audio_open_t o;
        memcpy(&o, pl, sizeof o);
        /* 合法 fmt：S16/S24/S32/DOP；FLOAT 拒（v1 未支持）。DOP 须带 AUDIO_FLAG_DSD（DoP 独立格式值）。 */
        int fmt_inval = (o.fmt != AUDIO_FMT_S16 && o.fmt != AUDIO_FMT_S24 &&
                         o.fmt != AUDIO_FMT_S32 && o.fmt != AUDIO_FMT_DOP);
        if (o.ch > 2 || o.ch < 1 || fmt_inval || (o.fmt == AUDIO_FMT_DOP && !(o.flags & AUDIO_FLAG_DSD)) || o.rate == 0) {
            m_audio_open_ack_t a; memset(&a, 0, sizeof a); a.err = MEOW_ERR_INVAL;
            send_frame(c->fd, MSG_AUDIO_OPEN_ACK, req_id, &a, sizeof a);
            logmsg("open rejected: ch=%u fmt=%d rate=%u flags=0x%x", (unsigned)o.ch, o.fmt, (unsigned)o.rate, (unsigned)o.flags);
            return;
        }
        /* DSD 可入性判定（BT 拒 / FILE-NULL 透传允许）；失败=报错关流（案 A，绝不静默退化） */
        if (o.fmt == AUDIO_FMT_DOP && dsd_enter() != 0) {
            m_audio_open_ack_t a; memset(&a, 0, sizeof a); a.err = MEOW_ERR_NODEV;
            send_frame(c->fd, MSG_AUDIO_OPEN_ACK, req_id, &a, sizeof a);
            logmsg("open rejected: DoP DSD not supported (target=%s sink=%d)", target_name(), g_sink);
            return;
        }
        /* 输出目标=BT：不依赖 DAC hw 探测（BT 走 pcm.bluealsa，与 hw:0,0/FGA numid=9 解耦）——
         * 探测只对 DAC 有意义；BT 打开失败在播放线程降级丢帧（plan §五自感知兜底）。 */
        if (g_target == AUDIO_OUT_DAC) {
            hw_probe();
            if (g_sink == SINK_ALSA && !g_hw_probed) {
                m_audio_open_ack_t a; memset(&a, 0, sizeof a); a.err = MEOW_ERR_NODEV;
                send_frame(c->fd, MSG_AUDIO_OPEN_ACK, req_id, &a, sizeof a);
                logmsg("open rejected: no usable PCM device (DAC)");
                return;
            }
        }
        int grant_fmt = target_grant_fmt(o.fmt);   /* DAC=hw 最优；BT=S16（plug 层转 codec 协商率）；FILE/NULL=保真透传 */
        uint32_t sid = g_next_sid++;
        /* 抢占：已有当前流 → 旧客户端收 PREEMPTED */
        if (g_st.active) {
            struct client *old = NULL;
            for (int i = 0; i < CLI_MAX; i++)
                if (g_cli[i].used && g_cli[i].sid == g_st.sid) { old = &g_cli[i]; break; }
            if (old && old != c) {
                m_audio_preempted_t p;
                memset(&p, 0, sizeof p);
                p.stream_id = g_st.sid;
                snprintf(p.by_app, sizeof p.by_app, "%s", o.app_id);
                send_frame(old->fd, MSG_AUDIO_PREEMPTED, 0, &p, sizeof p);
                old->state = CLS_DRAINING;
                logmsg("PREEMPTED stream %u by %s", (unsigned)g_st.sid, o.app_id);
            }
        }
        /* 授权新流 */
        c->sid = sid;
        c->state = CLS_OPEN;
        snprintf(c->app_id, sizeof c->app_id, "%s", o.app_id);
        g_st.active = 1;
        g_st.sid = sid;
        snprintf(g_st.app_id, sizeof g_st.app_id, "%s", o.app_id);
        g_st.rate = o.rate;
        g_st.ch = 2;                    /* DAC 双声道：mCh→stereo 由 SDK 复制 */
        g_st.fmt = (uint16_t)grant_fmt;
        g_paused = 0;
        g_written_frames = g_played_frames = 0;
        g_underrun = 0;
        g_drop_frames = 0;              /* 每流计数（txdrop 为全局客户端级，不随流清） */
        g_stall = 0;
        g_dev_bytes = 0;                /* 测试钩子计数随新流归零 */
        /* 电平表复位 + 窗口目标（~100ms；DoP DSD 无 PCM 意义，窗口=0 即跳过——meter_feed early-return） */
        g_m_win = (grant_fmt == AUDIO_FMT_DOP) ? 0 : (g_st.rate / 10);
        if (!g_m_win && grant_fmt != AUDIO_FMT_DOP) g_m_win = 1;
        g_m_sumsq = 0; g_m_peak = 0; g_m_frames = 0;
        g_lvl_rms_db10 = g_lvl_peak_db10 = METER_FLOOR_DB10;
        g_lvl_seq++;
        /* 重建 ring + 标记重配 */
        ring_rebuild();
        _audio_mark_reconfig_needed();
        m_audio_open_ack_t a;
        memset(&a, 0, sizeof a);
        a.stream_id = sid;
        a.grant_rate = o.rate;
        a.grant_ch = g_st.ch;
        a.grant_fmt = g_st.fmt;
        a.err = MEOW_OK;
        send_frame(c->fd, MSG_AUDIO_OPEN_ACK, req_id, &a, sizeof a);
        logmsg("OPEN grant: sid=%u app=%s rate=%u ch=%u fmt=%s target=%s codec=%s",
               (unsigned)sid, g_st.app_id, (unsigned)o.rate, (unsigned)g_st.ch,
               fmt_name((int)g_st.fmt), target_name(), g_bt_codec);
        break;
    }
    case MSG_AUDIO_WRITE: {
        /* 仅当前授权流、非 draining、非 paused 才入 ring；否则丢弃 */
        if (g_st.active && c->sid == g_st.sid && c->state != CLS_DRAINING && !g_paused && c->state != CLS_PAUSED) {
            size_t wn = ring_write_locked(pl, len, g_st.sid);
            int fs = frame_size();
            if (wn && fs > 0)
                g_written_frames += wn / (uint32_t)fs;
        }
        break;
    }
    case MSG_AUDIO_PAUSE:
    case MSG_AUDIO_RESUME:
    case MSG_AUDIO_STOP: {
        uint32_t sid = 0;
        if (len >= sizeof(uint32_t)) memcpy(&sid, pl, sizeof sid);
        if (sid == g_st.sid && g_st.active) {
            if (type == MSG_AUDIO_PAUSE)      { g_paused = 1; c->state = CLS_PAUSED; logmsg("pause sid=%u", (unsigned)sid); }
            else if (type == MSG_AUDIO_RESUME){ g_paused = 0; c->state = CLS_OPEN;   logmsg("resume sid=%u", (unsigned)sid); }
            /* PAUSE/RESUME 必须唤醒播放线程（它可能正 timedwait 在 paused 分支；
             * 旧代码 RESUME 不 signal，恢复后要等下一块 WRITE 才醒） */
            if (type != MSG_AUDIO_STOP)
                pthread_cond_signal(&g_cond);
            else /* STOP */ {
                logmsg("STOP sid=%u (app=%s)", (unsigned)sid, g_st.app_id);
                c->sid = 0;
                c->state = CLS_OPEN;
                session_end_locked();
            }
        } else if (type == MSG_AUDIO_STOP) {
            /* 非当前/已 draining 流：仅清客户端绑定 */
            if (c->sid == sid) { c->sid = 0; }
        }
        m_ack_t a; a.code = MEOW_OK; a.status = 0;
        send_frame(c->fd, MSG_ACK, req_id, &a, sizeof a);
        break;
    }
    case MSG_AUDIO_QUERY: {
        char txt[1024];
        /* 路由口用缓存值 g_route_cur（路由线程维护），不在 IO 热路径 popen amixer——
         * 驱动 wedge 时 amixer 虽有界但仍会拖慢 IO 循环 1.5s/次。 */
        int rb = g_route_cur;
        int vol = g_vol_pct;
        snprintf(txt, sizeof txt,
                 "active=%d app=%s sid=%u rate=%u ch=%u fmt=%s dsd=%d "
                 "written=%llu played=%llu underrun=%u dropped=%llu stall=%u txdrop=%u paused=%d "
                 "route_mode=%s port=%d vol=%d volctl=%s rms=%d peak=%d lvlseq=%u "
                 "target=%s codec=%s\n",
                 g_st.active ? 1 : 0,
                 g_st.active ? g_st.app_id : "-",
                 (unsigned)g_st.sid, (unsigned)g_st.rate, (unsigned)g_st.ch,
                 g_st.active ? fmt_name((int)g_st.fmt) : "-",
                 g_dsd_active ? 1 : 0,
                 (unsigned long long)g_written_frames,
                 (unsigned long long)g_played_frames,
                 (unsigned)g_underrun,
                 (unsigned long long)g_drop_frames,
                 (unsigned)g_stall, (unsigned)g_txdrop, g_paused,
                 g_route_manual == -1 ? "auto" : "manual",
                 (g_route_manual != -1 ? g_route_manual : rb),
                 vol, volctl_name(),
                 g_lvl_rms_db10, g_lvl_peak_db10, (unsigned)g_lvl_seq,
                 target_name(), g_bt_codec);
        send_frame(c->fd, MSG_AUDIO_STATE, req_id, txt, (uint32_t)strlen(txt) + 1);
        break;
    }
    case MSG_AUDIO_ROUTE: {
        uint32_t port = 0;
        if (len >= sizeof(uint32_t)) memcpy(&port, pl, sizeof port);
        if (port == 0) { g_route_manual = -1; logmsg("route manual -> auto"); }
        else if (port == 2 || port == 3) { g_route_manual = (int)port; apply_route((int)port); }
        else { logmsg("route: invalid port %u", (unsigned)port); }
        m_ack_t a; a.code = MEOW_OK; a.status = 0;
        send_frame(c->fd, MSG_ACK, req_id, &a, sizeof a);
        break;
    }
    case MSG_AUDIO_VOLUME: {
        int32_t pct = -1;
        if (len >= sizeof(int32_t)) memcpy(&pct, pl, sizeof pct);
        if (pct >= 0) {
            /* 音量应用含 BT 隔离：target=BT 时绝不下发 DAC 反转（vol_apply 内判断） */
            vol_apply((int)pct);
        } else {
            g_vol_pct = settings_get_volume();
        }
        m_ack_t a; a.code = MEOW_OK; a.status = (uint32_t)g_vol_pct;
        send_frame(c->fd, MSG_ACK, req_id, &a, sizeof a);
        break;
    }
    case MSG_AUDIO_OUTPUT: {
        uint32_t target = AUDIO_OUT_DAC;
        if (len >= sizeof(uint32_t)) memcpy(&target, pl, sizeof target);
        target_set((int)target);
        m_ack_t a; a.code = MEOW_OK; a.status = (uint32_t)g_target;
        send_frame(c->fd, MSG_ACK, req_id, &a, sizeof a);
        break;
    }
    default:
        break;
    }
}

/* 需要时标着重配：参数与当前设备不同才重开 */
static void _audio_mark_reconfig_needed(void)
{
    if (!g_dev_open || g_dev_rate != g_st.rate || g_dev_ch != g_st.ch || g_dev_fmt != g_st.fmt)
        g_reconfig_pending = 1;
    pthread_cond_signal(&g_cond);
}

/* 读客户端帧（调用方已持 g_mu）。读失败（EOF/错）→ 回收。 */
static void cx_read_frames(struct client *c)
{
    ssize_t r = read(c->fd, c->rbuf + c->rlen, sizeof c->rbuf - c->rlen);
    if (r <= 0) {
        if (r < 0 && (errno == EAGAIN || errno == EWOULDBLOCK)) return;
        cli_free(c);
        return;
    }
    c->rlen += (size_t)r;
    /* 处理所有完整帧 */
    while (c->rlen >= MEOW_IPC_HDR_LEN) {
        uint32_t magic, len;
        uint16_t ver, type;
        memcpy(&magic, c->rbuf, 4);
        memcpy(&ver, c->rbuf + 4, 2);
        memcpy(&type, c->rbuf + 6, 2);
        memcpy(&len, c->rbuf + 12, 4);
        if (magic != MEOW_IPC_MAGIC || ver != MEOW_IPC_VERSION) {
            logmsg("bad frame from client (magic=%08x ver=%u) -> drop conn", (unsigned)magic, (unsigned)ver);
            cli_free(c);
            return;
        }
        if (len > MEOW_IPC_MAX) {
            logmsg("frame too long (%u) -> drop conn", (unsigned)len);
            cli_free(c);
            return;
        }
        size_t total = MEOW_IPC_HDR_LEN + len;
        if (c->rlen < total) break;
        uint32_t req_id;
        memcpy(&req_id, c->rbuf + 8, 4);
        dispatch(c, type, req_id, c->rbuf + MEOW_IPC_HDR_LEN, len);
        memmove(c->rbuf, c->rbuf + total, c->rlen - total);
        c->rlen -= total;
    }
}

/* ---- IO 线程主体 ---- */
static void *io_thread(void *arg)
{
    (void)arg;
    int lfd = socket(AF_UNIX, SOCK_STREAM, 0);
    if (lfd < 0) { logmsg("io: socket: %s", strerror(errno)); return NULL; }
    struct sockaddr_un a;
    memset(&a, 0, sizeof a);
    a.sun_family = AF_UNIX;
    snprintf(a.sun_path, sizeof a.sun_path, "%s", g_sock);
    unlink(g_sock);
    if (bind(lfd, (struct sockaddr *)&a, sizeof a) != 0) {
        logmsg("io: bind %s: %s", g_sock, strerror(errno));
        close(lfd);
        return NULL;
    }
    chmod(g_sock, 0666);
    if (listen(lfd, 8) != 0) { logmsg("io: listen: %s", strerror(errno)); close(lfd); return NULL; }
    logmsg("io thread listening on %s", g_sock);

    for (;;) {
        g_hb_io++;
        if (g_stop) break;
        struct pollfd pfds[CLI_MAX + 1];
        int n = 1;
        pfds[0].fd = lfd; pfds[0].events = POLLIN; pfds[0].revents = 0;
        for (int i = 0; i < CLI_MAX; i++) {
            if (!g_cli[i].used) continue;
            pfds[n].fd = g_cli[i].fd; pfds[n].events = POLLIN; pfds[n].revents = 0;
            n++;
        }
        int pr = poll(pfds, (nfds_t)n, 200);
        if (pr < 0) {
            if (errno == EINTR) continue;
            /* poll 出错绝不退出线程（listener 一丢就是全守护失联，CLI ECONNREFUSED）；
             * 记日志（限频）+ 短睡后继续。 */
            static unsigned s_pollerr = 0;
            if ((s_pollerr++ & 15u) == 0) logmsg("io: poll err: %s (x%u, keep going)", strerror(errno), s_pollerr);
            struct timespec ts = { 0, 100 * 1000000L };
            nanosleep(&ts, NULL);
            continue;
        }
        /* pfds 是本轮新数组（revents 本轮清零），直接以 revents 为准（238 教训：每圈重建，
         * 杜绝陈旧 revents。勿在此清零）。 */
        struct pollfd snaps[CLI_MAX + 1];
        memcpy(snaps, pfds, sizeof snaps);
        pthread_mutex_lock(&g_mu);
        (void)pr;
        /* 处理 listen：一次 poll 收 1 个连接。**不可改用「while accept 排空积压」**——在连接
         * 风暴下（对端持续 connect）accept 永不 EAGAIN → 持 g_mu 无限循环 → IO 线程卡死、
         * 播放/路由/QUERY 全部被 g_mu 阻塞（宿主 T10 实测：drain 版风暴下 probe/OPEN 全 FAIL）。
         * 单次 accept + 下一轮 poll 再收，既有界又保持 listener/IO 可服务（原版行为即正确，
         * fd=N 反复 accept 是**对端短连接**所致，非本循环缺陷）。 */
        if ((snaps[0].revents & POLLIN)) {
            int cfd = accept(lfd, NULL, NULL);
            if (cfd >= 0) {
                fcntl(cfd, F_SETFL, fcntl(cfd, F_GETFL, 0) | O_NONBLOCK);
                int one = 1;
                setsockopt(cfd, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
                struct client *c = cli_alloc(cfd);
                if (!c) { close(cfd); logmsg("io: client limit reached, drop"); }
                else logmsg("io: client connected (fd=%d)", cfd);
            }
        }
        /* 处理客户读数（用本轮 revents 快照，避免连接被 cli_free 后误用） */
        for (int i = 1; i < n; i++) {
            if (snaps[i].revents == 0) continue;
            struct client *c = cli_by_fd(snaps[i].fd);
            if (!c) continue;
            if (snaps[i].revents & (POLLHUP | POLLERR | POLLNVAL)) { cli_free(c); continue; }
            if (snaps[i].revents & POLLIN) cx_read_frames(c);
        }
        pthread_mutex_unlock(&g_mu);
        /* 路由线程与播放线程独立；此处不再做 */
    }
    pthread_mutex_lock(&g_mu);
    for (int i = 0; i < CLI_MAX; i++) if (g_cli[i].used) cli_free(&g_cli[i]);
    pthread_mutex_unlock(&g_mu);
    close(lfd);
    return NULL;
}

/* ---- 路由线程主体 ---- */
static void *route_thread(void *arg)
{
    (void)arg;
    int last_hb = -1, last_bal = -1, last_target = -1;
    logmsg("route thread init (numid=9, %s)", g_amixer);
    /* M2.91 挂死根治（AUDIO_HANG_INVESTIGATION.md）：hbc3000 FPGA 未烧录+enable 时
     * 启动 PCM 会在第二次 hbc3000_start 死锁整机。写 Output Port Switch 是烧录触发器
     * （驱动 put：set_spdif_mode→program_ram→enabled）。开机端口恒 0=未烧，故启动时
     * 无条件写一次：4.4 在→3，3.5 在→2，都没→4（官方播放器拔插孔后的选择，保 FPGA 已烧）。
     * 端口已是目标值（audiod 重启场景，驱动同值短路不写）→ 先写 5(disable) 强制重烧。
     * ⚠️ P2 蓝牙：numnid=9/FPGA 武装只作用于 **DAC 物理路径**（plan §五解耦）；target=BT 时
     * 不开 hw:0,0，无 hbc3000 start 死锁风险，故 BT 期间跳过 numid=9/FPGA（切回 DAC 再武装）。 */
    int need_arm = 1;   /* 启动（DAC 起点）武装一次；BT 期间置 1（回 DAC 再武装） */
    while (!g_stop) {
        pthread_mutex_lock(&g_mu);
        int manual = g_route_manual;    /* 快照后放锁：amixer popen 不持 g_mu（防 wedge 级联） */
        int tgt = g_target;             /* 输出目标快照（决定是否武装 FPGA） */
        pthread_mutex_unlock(&g_mu);
        if (tgt == AUDIO_OUT_BT) {
            static int s_logged = 0;
            if (!s_logged) { s_logged = 1; logmsg("route: output=BT, numid=9/FPGA not armed (DAC dormant)"); }
            need_arm = 1;               /* 回 DAC 后补一次武装 */
            last_target = -1;
        } else {
            if (need_arm) {             /* 启动 or BT→DAC：一次性武装（同原 boot-arm） */
                int hb = read_switch("/sys/class/switch/headset/state");
                int bal = read_switch("/sys/class/switch/balance/state");
                int target = (bal == 1) ? 3 : (hb == 1) ? 2 : 4;
                int cur = amixer_get(9, 1);
                if (cur == target) { logmsg("route: port already %d, force re-arm via 5", target); apply_route(5); }
                apply_route(target);
                last_hb = hb; last_bal = bal; last_target = (hb == 0 && bal == 0) ? -1 : target;
                logmsg("route: boot/DAC-return arm done (port %d %s)", target, port_name(target));
                need_arm = 0;
            } else {
                route_evaluate(manual, &last_hb, &last_bal, &last_target);
            }
        }
        int naps = 5;   /* 1000ms / 200ms 分段，即时响应 SIGTERM */
        for (int k = 0; k < naps && !g_stop; k++) {
            struct timespec ts = { 0, 200 * 1000000L };
            nanosleep(&ts, NULL);
        }
    }
    return NULL;
}

/* ---- 全面监控日志（§8 扩展：流活跃时每 1s 一行；主线程节拍驱动，不碰播放线程） ---- */
/* deci-dB → "-13.1" 文本（静音地板显 "-inf"） */
static void fmt_db10(char *out, size_t n, int v)
{
    if (v <= METER_FLOOR_DB10) { snprintf(out, n, "-inf"); return; }
    int neg = v < 0;
    int a = neg ? -v : v;
    snprintf(out, n, "%s%d.%d", neg ? "-" : "", a / 10, a % 10);
}

static void mon_close(void)
{
    if (g_monfd >= 0) { close(g_monfd); g_monfd = -1; }
}

/* 主线程 1s 节拍调用。流活跃 → 懒打开 TF 卡 MeowOS/logs/audio_monitor_<bootts>.log
 * （无卡降级 /tmp）并写一行（时间戳+app+参数+rms/peak dBFS+帧计数+underrun/stall/
 * dropped/txdrop+路由口+FPGA 状态+音量%+hw 消费速率帧/s）；流停止即停写关文件。
 * 快照先取后写：文件 IO 不持 g_mu。 */
static void mon_tick(void)
{
    pthread_mutex_lock(&g_mu);
    int active = g_st.active;
    char app[MEOW_APP_ID_MAX]; snprintf(app, sizeof app, "%s", g_st.app_id);
    uint32_t sid = g_st.sid, rate = g_st.rate;
    unsigned ch = g_st.ch, fmt = g_st.fmt;
    uint64_t wr = g_written_frames, pl = g_played_frames, dr = g_drop_frames;
    unsigned ur = g_underrun, st = g_stall, tx = g_txdrop;
    int paused = g_paused, vol = g_vol_pct, rmanual = g_route_manual, rcur = g_route_cur;
    int rms = g_lvl_rms_db10, pk = g_lvl_peak_db10;
    pthread_mutex_unlock(&g_mu);

    if (!active) {                          /* 流停止即停写 */
        if (g_monfd >= 0) {
            mon_close();
            logmsg("monitor log closed (stream ended)");
        }
        g_mon_prev_ms = 0;
        return;
    }
    struct timespec tp;
    clock_gettime(CLOCK_MONOTONIC, &tp);
    int64_t now_ms = (int64_t)tp.tv_sec * 1000 + tp.tv_nsec / 1000000;
    if (g_monfd < 0) {                      /* 懒打开（流开始才建文件） */
        char ts[64];
        get_bootts(ts, sizeof ts);
        char path[368];
        if (access(LOG_DIR_CARD, W_OK) == 0)
            snprintf(path, sizeof path, "%s/audio_monitor_%s.log", LOG_DIR_CARD, ts);
        else
            snprintf(path, sizeof path, "/tmp/audio_monitor_%s.log", ts);
        g_monfd = open(path, O_WRONLY | O_CREAT | O_APPEND, 0644);
        if (g_monfd < 0) return;            /* 打不开就静默降级（下拍再试） */
        logmsg("monitor log -> %s", path);
        const char *hdr = "# meow_audiod monitor: time | app sid rate/ch/fmt | rms/peak dBFS | written played underrun stall dropped txdrop | route fpga vol hwrate\n";
        if (write(g_monfd, hdr, strlen(hdr)) < 0) { }
        g_mon_prev_played = pl;
        g_mon_prev_ms = now_ms;
    }
    int64_t dt = now_ms - g_mon_prev_ms;
    uint64_t hwrate = (dt > 0 && pl >= g_mon_prev_played)
                      ? (pl - g_mon_prev_played) * 1000 / (uint64_t)dt : 0;
    g_mon_prev_played = pl;
    g_mon_prev_ms = now_ms;
    struct tm tm;
    time_t now = time(NULL);
    localtime_r(&now, &tm);
    char tbuf[32];
    strftime(tbuf, sizeof tbuf, "%Y-%m-%d %H:%M:%S", &tm);
    char rmsb[16], pkb[16];
    fmt_db10(rmsb, sizeof rmsb, rms);
    fmt_db10(pkb, sizeof pkb, pk);
    int port = (rmanual != -1) ? rmanual : rcur;
    char line[512];
    int n = snprintf(line, sizeof line,
                     "%s app=%s sid=%u %uHz/%uch/%s dsd=%d "
                     "rms=%sdBFS peak=%sdBFS "
                     "written=%llu played=%llu underrun=%u stall=%u dropped=%llu txdrop=%u "
                     "route=%d(%s) fpga=%s vol=%d%% hwrate=%lluf/s%s\n",
                     tbuf, app, (unsigned)sid, (unsigned)rate, ch, fmt_name((int)fmt),
                     (fmt == AUDIO_FMT_DOP ? 1 : 0),
                     rmsb, pkb,
                     (unsigned long long)wr, (unsigned long long)pl,
                     ur, st, (unsigned long long)dr, tx,
                     port, port_name(port),
                     rcur >= 0 ? "armed" : "unknown",
                     vol, (unsigned long long)hwrate,
                     paused ? " paused" : "");
    if (n > 0 && write(g_monfd, line, (size_t)n) < 0) { }
}

static void on_sig(int sig)
{
    (void)sig;
    /* 只置标志（async-signal-safe）：所有等待均为有界 timedwait（播放 1s / IO poll 200ms /
     * 路由 200ms 分段 / ring 写 ≤g_ring_wait_ms），线程自行看到 g_stop 退出——
     * 不在信号处理器里调 pthread_cond_signal（非 async-signal-safe）。 */
    g_stop = 1;
}

int main(int argc, char **argv)
{
    const char *e;
    /* 参数/env 覆盖 */
    for (int i = 1; i < argc; i++) {
        if (!strcmp(argv[i], "--sock") && i + 1 < argc) snprintf(g_sock, sizeof g_sock, "%s", argv[++i]);
        else if (!strcmp(argv[i], "--out") && i + 1 < argc) snprintf(g_out_wav, sizeof g_out_wav, "%s", argv[++i]);
        else if (!strcmp(argv[i], "-h") || !strcmp(argv[i], "--help")) {
            printf("meow_audiod [--sock <path>] [--out <wav>]\n"
                   "  env: MEOW_AUDIO_SOCK/MEOW_AUDIO_OUT/MEOW_AUDIO_SINK(alsa|file|null)/MEOW_AUDIO_AMIXER/MEOW_AUDIO_FORCE=1\n"
                   "       MEOW_AUDIO_SETTINGS (settings.conf 路径, 缺省 %s; 宿主测覆盖)\n"
                   "       MEOW_AUDIO_TARGET (0=dac 1=bt, 覆盖 settings audio.output_bt)\n"
                   "       MEOW_AUDIO_RING_WAIT_MS (ring 满写等待上限, 缺省 5000)\n"
                   "       MEOW_AUDIO_TEST_WRITE_DELAY_MS / MEOW_AUDIO_TEST_WEDGE_AFTER_BYTES / MEOW_AUDIO_AMIXER_TRACE (故障注入/amixer 轨迹, 仅测试)\n",
                   SETTINGS_CONF);
            return 0;
        }
    }
    if ((e = getenv("MEOW_AUDIO_SOCK")) && e[0]) snprintf(g_sock, sizeof g_sock, "%s", e);
    if ((e = getenv("MEOW_AUDIO_OUT")) && e[0]) snprintf(g_out_wav, sizeof g_out_wav, "%s", e);
    if ((e = getenv("MEOW_AUDIO_AMIXER")) && e[0]) g_amixer = e;
    if ((e = getenv("MEOW_AUDIO_FORCE")) && e[0] == '1') g_force = 1;
    if ((e = getenv("MEOW_AUDIO_RING_WAIT_MS")) && atoi(e) > 0) g_ring_wait_ms = atoi(e);
    if ((e = getenv("MEOW_AUDIO_TEST_WRITE_DELAY_MS")) && atoi(e) > 0) g_test_write_delay_ms = atoi(e);
    if ((e = getenv("MEOW_AUDIO_TEST_WEDGE_AFTER_BYTES")) && atoll(e) > 0) g_test_wedge_after = atoll(e);
    if ((e = getenv("MEOW_AUDIO_AMIXER_TRACE")) && e[0]) snprintf(g_amixer_trace_path, sizeof g_amixer_trace_path, "%s", e);
    if ((e = getenv("MEOW_AUDIO_SETTINGS")) && e[0]) snprintf(g_settings_path, sizeof g_settings_path, "%s", e);
    const char *sink = getenv("MEOW_AUDIO_SINK");
    if (sink && sink[0]) {
        if (!strcmp(sink, "file")) g_sink = SINK_FILE;
        else if (!strcmp(sink, "null")) g_sink = SINK_NULL;
        else if (!strcmp(sink, "alsa")) g_sink = SINK_ALSA;
    } else {
        /* 自动：/dev/snd/pcmC0D0p 存在 → ALSA；否则 FILE */
        if (access(DEV_PCM, F_OK) == 0) g_sink = SINK_ALSA;
        else g_sink = SINK_FILE;
    }

    signal(SIGPIPE, SIG_IGN);
    signal(SIGTERM, on_sig);
    signal(SIGINT, on_sig);

    /* --- 启动门控（红线） --- */
    if (!boot_mode_ok()) {
        fprintf(stderr, "[audiod] not MeowOS mode (/tmp/meow_boot_mode != meow), exit\n");
        return 0;
    }

    log_open();
    logmsg("meow_audiod start: sock=%s sink=%d wav=%s force=%d ring_wait=%dms%s%s",
           g_sock, g_sink, g_out_wav, g_force, g_ring_wait_ms,
           g_test_write_delay_ms > 0 ? " TEST-DELAY" : "",
           g_test_wedge_after >= 0 ? " TEST-WEDGE" : "");
    /* P2 蓝牙：读 settings.conf（可经 env 覆盖）→ 输出目标 + codec。env MEOW_AUDIO_TARGET
     * 优先级最高（宿主测/调试用），否则 `audio.output_bt`。 */
    settings_get_bt_codec();
    g_target = settings_get_output_target();
    if ((e = getenv("MEOW_AUDIO_TARGET")) && e[0]) {
        int t = atoi(e);
        if (t == AUDIO_OUT_BT) g_target = AUDIO_OUT_BT;
        else if (t == AUDIO_OUT_DAC) g_target = AUDIO_OUT_DAC;
    }
    if (g_sink == SINK_ALSA && g_target == AUDIO_OUT_DAC) hw_probe();
    g_vol_pct = settings_get_volume();
    logmsg("volume init = %d%% target=%s codec=%s volctl=%s",
           g_vol_pct, target_name(), g_bt_codec, volctl_name());

    /* g_cond 用 CLOCK_MONOTONIC（所有 timedwait 的基准；防系统时间跳变影响护栏超时） */
    {
        pthread_condattr_t ca;
        pthread_condattr_init(&ca);
        pthread_condattr_setclock(&ca, CLOCK_MONOTONIC);
        pthread_cond_init(&g_cond, &ca);
        pthread_condattr_destroy(&ca);
    }

    pthread_t ti, tp, tr;
    pthread_create(&ti, NULL, io_thread, NULL);
    pthread_create(&tp, NULL, playback_thread, NULL);
    pthread_create(&tr, NULL, route_thread, NULL);

    /* 主线程 = watchdog：心跳静默 >WD_SILENT_SEC 秒即告警（只告警不强杀——
     * 对卡在内核的线程任何外部干预都不安全；护栏保证其它线程/连接继续服务）。 */
    unsigned last_io = 0, last_play = 0;
    int io_silent = 0, play_silent = 0;
    while (!g_stop) {
        struct timespec ts = { 1, 0 };
        nanosleep(&ts, NULL);
        if (g_stop) break;
        unsigned io = g_hb_io, pl = g_hb_play;
        io_silent   = (io == last_io)   ? io_silent + 1   : 0;  last_io = io;
        play_silent = (pl == last_play) ? play_silent + 1 : 0;  last_play = pl;
        if (io_silent == WD_SILENT_SEC || (io_silent > WD_SILENT_SEC && io_silent % 30 == 0))
            logmsg("WATCHDOG: io thread silent %ds (accept/read loop stuck?)", io_silent);
        if (play_silent == WD_SILENT_SEC || (play_silent > WD_SILENT_SEC && play_silent % 30 == 0)) {
            pthread_mutex_lock(&g_mu);
            int act = g_st.active;
            uint64_t wr = g_written_frames, plf = g_played_frames;
            pthread_mutex_unlock(&g_mu);
            logmsg("WATCHDOG: playback thread silent %ds (active=%d written=%llu played=%llu, device wedged?)",
                   play_silent, act, (unsigned long long)wr, (unsigned long long)plf);
        }
        mon_tick();                         /* 流活跃才写监控日志（无流零开销） */
    }
    logmsg("meow_audiod shutdown");
    mon_close();
    pthread_join(ti, NULL);
    pthread_join(tp, NULL);
    pthread_join(tr, NULL);
    unlink(g_sock);
    if (g_logfd >= 0) close(g_logfd);
    return 0;
}