feat: 右上角添加软急停滑块（平行四边形风格）

新增 EmergencyStopSlider 组件，水平滑到右侧触发软急停指令，
滑到左侧仅 UI 复位，等待机器人状态上报自动归位。非拖动时
跟随 motionState 状态同步滑块位置。

ControlCommands 新增 softEmergencyStop() 便捷函数。

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

AGENTS.md

@@ -161,7 +161,7 @@ gradlew installDebug
 - **状态管理**: 使用 `StateFlow` 暴露连接状态、机器人状态
 - **生命周期**: 网络连接生命周期绑定到 Activity/Service，前台时活跃
 - **MsgId**: 从 0 递增 u16，循环回绕
-- **断线判定**: 3 秒无任何 UDP 包 → 标记离线
+- **断线判定**: 收到首个有效数据包前为 `CONNECTING`（5 秒无数据 → `TIMEOUT`）；`CONNECTED` 后 3 秒无任何 UDP 包 → `TIMEOUT`
 
 ---
 
@@ -200,8 +200,20 @@ gradlew installDebug
 - [x] UI 布局：连接按钮合并到顶部 StatusBar 的 ConnectionIndicator，删除底部独立连接按钮
 - [x] UI 布局：ConnectionIndicator 改为按钮形态（Surface + 圆角边框），仅指示器区域可点击切换连接
 - [x] UI 布局：隐藏系统状态栏（WindowInsetsControllerCompat），压缩自定义 StatusBar 高度，扩展可视区域
+- [x] UI 布局：功能按钮均布在四周——左上角模式选择+步态切换+起立/趴下，右上角灯光+休眠+充电，充分利用屏幕空间，优化单手操作体验
+- [x] UI 布局：起立/趴下合并为切换按钮（琥珀色=站立时显示"趴下"，暗色=非站立时显示"起立"），移至左上角 StatusBar 下方
+- [x] UI 布局：模式选择器（常规/导航/辅助，3个互斥按钮，无缝隙，底色显示当前模式）移至左上角，位于起立/趴上方
+- [x] UI 布局：步态切换（基础/楼梯/平地敏捷/楼梯敏捷，4个互斥按钮，无缝隙）移至模式选择器下方，始终显示，仅普通模式+RL控制时可点击
+- [x] UI 布局：照明/休眠/充电移至右上角，紧凑排列（前灯后灯无缝隙一行，休眠/唤醒切换，充电/充电中切换）
+- [x] UI 布局：底部控制区移除"更多"展开区域，仅保留左右摇杆
+- [x] UI 布局：所有功能按钮统一使用平行四边形形状（左侧按钮斜边左下→右上，右侧按钮斜边左上→右下）
+- [x] UI 布局：所有控制按钮在未连接时灰色不可点击
+- [x] 连接状态准确性修复：`ProtocolClient` 收到首个有效数据包后才标记 `CONNECTED`，不再 socket 创建后立即标记；`CONNECTING` 状态 5 秒无响应自动超时回退 `TIMEOUT`
+- [x] 连接按钮交互优化：`CONNECTING` 状态下点击连接按钮仅断开回到 `DISCONNECTED`，不再自动重连，由用户手动再次点击发起重试
+- [x] 状态机补充：`RobotConnection` 允许 `CONNECTING → TIMEOUT` 合法转换
+- [x] 心跳启动时机修复：`ProtocolClient.connect()` 立即启动心跳线程，不再等待首次收到数据包后才启动；心跳在 `CONNECTING` 和 `CONNECTED` 状态下均正常运行
+- [x] 软急停滑块：右上角新增平行四边形水平滑块，滑到右侧触发软急停（`MOTION_DAMPING`），跟随机器人状态上报自动归位
 
 ### 待办
 
-- [ ] UI 布局：功能按钮均布在四周，充分利用屏幕空间，优化单手操作体验
 - [ ] 视频进一步延迟优化：探索更激进的低延迟策略（如降低帧率、缩小分辨率、调整 ExoPlayer 缓冲策略等）

app/src/main/java/com/example/m20_gamepad/network/ProtocolClient.kt

@@ -89,9 +89,11 @@ class ProtocolClient(
     /**
      * 建立连接：
      * 1. 创建 UDP socket
-     * 2. 启动接收协程
+     * 2. 启动接收/发送协程
      * 3. 发送订阅请求
-     * 4. 启动心跳和断线检测
+     * 4. 启动断线检测（CONNECTING 5s / CONNECTED 3s 无数据 → TIMEOUT）
+     * 5. 启动心跳 1Hz（立即发送，覆盖 CONNECTING 和 CONNECTED 状态）
+     * 6. 首次收到有效数据包后标记已连接
      */
     fun connect() {
         if (_state.value != State.DISCONNECTED && _state.value != State.ERROR) return
@@ -131,17 +133,15 @@ class ProtocolClient(
             // 发送订阅请求（触发服务端 UDP 推送）
             sendSubscriptionRequests()
 
-            _state.value = State.CONNECTED
+            // 启动断线检测（立即开始，覆盖 CONNECTING 和 CONNECTED 状态）
-
-            // 启动心跳
-            heartbeatJob = scope.launch(Dispatchers.IO) {
-                heartbeatLoop(sock, address)
-            }
-
-            // 启动断线检测
             timeoutJob = scope.launch {
                 timeoutCheckLoop()
             }
+
+            // 启动心跳（立即开始，覆盖 CONNECTING 和 CONNECTED 状态）
+            heartbeatJob = scope.launch(Dispatchers.IO) {
+                heartbeatLoop(sock, address)
+            }
         } catch (e: Exception) {
             _state.value = State.ERROR
             closeSocket()
@@ -232,6 +232,11 @@ class ProtocolClient(
                 if (report != null) {
                     _statusReport.tryEmit(report)
                 }
+
+                // 首次收到有效数据包：标记已连接
+                if (_state.value == State.CONNECTING) {
+                    _state.value = State.CONNECTED
+                }
             } catch (_: SocketTimeoutException) {
                 // 超时正常，继续循环
                 continue
@@ -244,9 +249,11 @@ class ProtocolClient(
         }
     }
 
-    /** 心跳循环（1 Hz） */
+    /** 心跳循环（1 Hz）—— 在 CONNECTING 和 CONNECTED 状态下运行 */
     private suspend fun CoroutineScope.heartbeatLoop(sock: DatagramSocket, address: InetAddress) {
-        while (isActive && _state.value == State.CONNECTED) {
+        while (isActive &&
+            (_state.value == State.CONNECTING || _state.value == State.CONNECTED)
+        ) {
             try {
                 val json = ControlCommands.heartbeat()
                 val packet = encoder.encode(json)
@@ -258,13 +265,23 @@ class ProtocolClient(
         }
     }
 
-    /** 断线检测：3 秒无数据 → 标记 TIMEOUT */
+    /** 断线检测：CONNECTED 状态 3 秒无数据 → TIMEOUT；CONNECTING 状态 5 秒无数据 → TIMEOUT */
     private suspend fun CoroutineScope.timeoutCheckLoop() {
         while (isActive && _state.value != State.DISCONNECTED) {
             val elapsed = System.currentTimeMillis() - lastPacketTimeMs
-            if (elapsed > 3000 && _state.value == State.CONNECTED) {
+            when (_state.value) {
+                State.CONNECTED -> {
+                    if (elapsed > 3000) {
                         _state.value = State.TIMEOUT
                     }
+                }
+                State.CONNECTING -> {
+                    if (elapsed > 5000) {
+                        _state.value = State.TIMEOUT
+                    }
+                }
+                else -> { /* DISCONNECTED/TIMEOUT/ERROR: 无需超时处理 */ }
+            }
             delay(500)
         }
     }

app/src/main/java/com/example/m20_gamepad/network/models/ControlCommands.kt

@@ -107,6 +107,9 @@ object ControlCommands {
         put("Charge", JsonPrimitive(charge))
     }
 
+    // ---- 2.8b 软急停 ----
+    fun softEmergencyStop(time: String = now()): String = motionControl(MOTION_DAMPING, time)
+
     // ---- 2.9 休眠模式设置 ----
     fun sleepSettings(sleep: Boolean, auto: Boolean, timeMinutes: Int, time: String = now()): String = buildAsdu(
         type = 1101, command = 6, time = time

app/src/main/java/com/example/m20_gamepad/service/RobotConnection.kt

@@ -50,6 +50,7 @@ class RobotConnection {
             ProtocolClient.State.CONNECTING ->
                 to == ProtocolClient.State.CONNECTED ||
                 to == ProtocolClient.State.ERROR ||
+                to == ProtocolClient.State.TIMEOUT ||
                 to == ProtocolClient.State.DISCONNECTED
             ProtocolClient.State.CONNECTED ->
                 to == ProtocolClient.State.TIMEOUT ||

app/src/main/java/com/example/m20_gamepad/ui/MainScreen.kt

@@ -3,6 +3,7 @@ package com.example.m20_gamepad.ui
 import androidx.compose.foundation.Image
 import androidx.compose.foundation.background
 import androidx.compose.foundation.BorderStroke
+import androidx.compose.foundation.gestures.detectHorizontalDragGestures
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -13,14 +14,13 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.navigationBars
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.layout.windowInsetsPadding
-import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Info
 import androidx.compose.material.icons.filled.Settings
@@ -40,12 +40,21 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.Outline
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.Shape
+import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.sp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
@@ -66,6 +75,38 @@ import com.example.m20_gamepad.video.RtspVideoPlayer
 private val OverlayBg = Color(0x88000000)
 private val OverlayText = Color.White
 
+/** 平行四边形形状，用于功能按钮。skewLeft=true → 左下-右上斜边（左侧按钮）；
+ *  skewLeft=false → 左上-右下斜边（右侧按钮）。 */
+private class ParallelogramShape(
+    private val skewDp: Dp = 10.dp,
+    private val skewLeft: Boolean = true
+) : Shape {
+    override fun createOutline(
+        size: Size,
+        layoutDirection: LayoutDirection,
+        density: Density
+    ): Outline {
+        val skewPx = with(density) { skewDp.toPx() }
+        val path = Path().apply {
+            if (skewLeft) {
+                // 左下 → 右上 斜边（平行四边形向右倾斜）
+                moveTo(skewPx, 0f)
+                lineTo(size.width, 0f)
+                lineTo(size.width - skewPx, size.height)
+                lineTo(0f, size.height)
+            } else {
+                // 左上 → 右下 斜边（平行四边形向左倾斜）
+                moveTo(0f, 0f)
+                lineTo(size.width - skewPx, 0f)
+                lineTo(size.width, size.height)
+                lineTo(skewPx, size.height)
+            }
+            close()
+        }
+        return Outline.Generic(path)
+    }
+}
+
 /**
  * 主界面：RTSP 视频背景 + 双摇杆覆盖层 + 状态栏 + 控制按钮。
  *
@@ -135,7 +176,9 @@ fun MainScreen(
             onStatusClick = { statusPanelVisible = true },
             onSettingsClick = onSettingsClick,
             onConnectToggle = {
-                if (connectionState == ProtocolClient.State.CONNECTED) {
+                if (connectionState == ProtocolClient.State.CONNECTED ||
+                    connectionState == ProtocolClient.State.CONNECTING
+                ) {
                     viewModel.disconnect()
                 } else {
                     viewModel.connect()
@@ -144,12 +187,95 @@ fun MainScreen(
             modifier = Modifier.align(Alignment.TopCenter)
         )
 
+        // ---- 左上角控制区：模式选择 + 步态切换 + 起立/趴下 ----
+        Column(
+            modifier = Modifier
+                .align(Alignment.TopStart)
+                .padding(top = 56.dp, start = 12.dp),
+            verticalArrangement = Arrangement.spacedBy(6.dp)
+        ) {
+            ModeSelector(
+                currentMode = status?.basicStatus?.controlUsageMode ?: 0,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onSelectMode = { mode -> viewModel.sendSwitchMode(mode) }
+            )
+            // 步态切换——始终显示，仅普通模式 + RL 控制时可点击
+            GaitSelector(
+                currentGait = status?.basicStatus?.gait ?: 0,
+                enabled = connectionState == ProtocolClient.State.CONNECTED &&
+                        motionState == ControlCommands.MOTION_RL_CONTROL &&
+                        status?.basicStatus?.controlUsageMode == ControlCommands.MODE_NORMAL,
+                onSelectGait = { gait -> viewModel.sendSwitchGait(gait) }
+            )
+            StandToggleButton(
+                motionState = motionState,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onToggle = {
+                    if (motionState == ControlCommands.MOTION_IDLE ||
+                        motionState == ControlCommands.MOTION_LIE_DOWN
+                    ) {
+                        viewModel.sendMotionControl(ControlCommands.MOTION_STAND)
+                    } else {
+                        viewModel.sendMotionControl(ControlCommands.MOTION_LIE_DOWN)
+                    }
+                }
+            )
+        }
+
+        // ---- 右上角控制区：软急停滑块 + 照明 + 休眠 + 充电 ----
+        Column(
+            modifier = Modifier
+                .align(Alignment.TopEnd)
+                .padding(top = 56.dp, end = 12.dp),
+            horizontalAlignment = Alignment.End,
+            verticalArrangement = Arrangement.spacedBy(6.dp)
+        ) {
+            // 软急停滑块
+            EmergencyStopSlider(
+                isEmergencyStop = motionState == ControlCommands.MOTION_DAMPING,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onEmergencyStop = { viewModel.sendEmergencyStop() }
+            )
+            // 照明：前灯+后灯，无缝隙
+            val frontOn = ledStatus?.front == 1
+            val backOn = ledStatus?.back == 1
+            Row(horizontalArrangement = Arrangement.spacedBy(0.dp)) {
+                LightToggleButton(
+                    text = "前灯",
+                    isOn = frontOn,
+                    enabled = connectionState == ProtocolClient.State.CONNECTED
+                ) {
+                    viewModel.sendLightControl(if (frontOn) 0 else 1, ledStatus?.back ?: 0)
+                }
+                LightToggleButton(
+                    text = "后灯",
+                    isOn = backOn,
+                    enabled = connectionState == ProtocolClient.State.CONNECTED
+                ) {
+                    viewModel.sendLightControl(ledStatus?.front ?: 0, if (backOn) 0 else 1)
+                }
+            }
+            // 休眠/唤醒
+            val isSleeping = status?.basicStatus?.sleep == 1
+            SleepToggleButton(
+                isSleeping = isSleeping,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onToggle = { viewModel.sendSleepSettings(!isSleeping) }
+            )
+            // 充电/结束充电
+            val isCharging = status?.basicStatus?.charge == 1
+            ChargeToggleButton(
+                isCharging = isCharging,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onToggle = { viewModel.sendChargeControl(if (isCharging) 0 else 1) }
+            )
+        }
+
         // ---- 底部控制区 ----
         BottomControls(
             viewModel = viewModel,
             connectionState = connectionState,
             motionState = motionState,
-            ledStatus = ledStatus,
             modifier = Modifier
                 .align(Alignment.BottomCenter)
                 .windowInsetsPadding(WindowInsets.navigationBars)
@@ -336,7 +462,6 @@ private fun BottomControls(
     viewModel: MainViewModel,
     connectionState: ProtocolClient.State,
     motionState: Int,
-    ledStatus: LedStatus?,
     modifier: Modifier = Modifier
 ) {
     Row(
@@ -357,14 +482,6 @@ private fun BottomControls(
             }
         )
 
-        // 中间控制按钮组
-        ControlButtons(
-            viewModel = viewModel,
-            connectionState = connectionState,
-            motionState = motionState,
-            ledStatus = ledStatus
-        )
-
         // 右摇杆（Yaw 旋转）
         Joystick(
             modifier = Modifier.size(180.dp),
@@ -378,170 +495,6 @@ private fun BottomControls(
     }
 }
 
-@Composable
-private fun ControlButtons(
-    viewModel: MainViewModel,
-    connectionState: ProtocolClient.State,
-    motionState: Int,
-    ledStatus: LedStatus?
-) {
-    val connected = connectionState == ProtocolClient.State.CONNECTED
-    val isRlControl = motionState == ControlCommands.MOTION_RL_CONTROL
-    var showMore by remember { mutableStateOf(false) }
-    val scrollState = rememberScrollState()
-
-    Column(
-        horizontalAlignment = Alignment.CenterHorizontally,
-        verticalArrangement = Arrangement.spacedBy(6.dp),
-        modifier = Modifier
-            .verticalScroll(scrollState)
-            .padding(top = 4.dp, bottom = 4.dp)
-    ) {
-        // 运动状态转换
-        ControlButton(
-            "起立",
-            enabled = connected && (motionState == ControlCommands.MOTION_IDLE ||
-                    motionState == ControlCommands.MOTION_LIE_DOWN)
-        ) {
-            viewModel.sendMotionControl(ControlCommands.MOTION_STAND)
-        }
-        ControlButton(
-            "RL控制",
-            enabled = connected && motionState == ControlCommands.MOTION_STAND
-        ) {
-            viewModel.sendMotionControl(ControlCommands.MOTION_RL_CONTROL)
-        }
-        ControlButton(
-            "趴下",
-            enabled = connected && motionState != ControlCommands.MOTION_LIE_DOWN
-        ) {
-            viewModel.sendMotionControl(ControlCommands.MOTION_LIE_DOWN)
-        }
-
-        // 步态切换——仅 RL 控制
-        if (isRlControl) {
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("基础", enabled = isRlControl) {
-                    viewModel.sendSwitchGait(ControlCommands.GAIT_BASIC)
-                }
-                MiniButton("楼梯", enabled = isRlControl) {
-                    viewModel.sendSwitchGait(ControlCommands.GAIT_STAIRS)
-                }
-                MiniButton("平地敏捷", enabled = isRlControl) {
-                    viewModel.sendSwitchGait(ControlCommands.GAIT_FLAT_AGILE)
-                }
-            }
-            MiniButton("楼梯敏捷", enabled = isRlControl) {
-                viewModel.sendSwitchGait(ControlCommands.GAIT_STAIRS_AGILE)
-            }
-        }
-
-        // 更多/收起切换
-        if (connected) {
-            ControlButton(if (showMore) "收起" else "更多", enabled = connected) {
-                showMore = !showMore
-            }
-        }
-
-        // ---- 更多控制（可展开） ----
-        if (showMore) {
-            Separator()
-
-            // 使用模式
-            SectionLabel("使用模式")
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("常规") {
-                    viewModel.sendSwitchMode(ControlCommands.MODE_NORMAL)
-                }
-                MiniButton("导航") {
-                    viewModel.sendSwitchMode(ControlCommands.MODE_NAVIGATION)
-                }
-                MiniButton("辅助") {
-                    viewModel.sendSwitchMode(ControlCommands.MODE_ASSIST)
-                }
-            }
-            Spacer(Modifier.height(4.dp))
-
-            // 照明
-            SectionLabel("照明")
-            val frontOn = ledStatus?.front == 1
-            val backOn = ledStatus?.back == 1
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                LightToggleButton(
-                    text = "前灯",
-                    isOn = frontOn,
-                    enabled = connected
-                ) {
-                    viewModel.sendLightControl(if (frontOn) 0 else 1, ledStatus?.back ?: 0)
-                }
-                LightToggleButton(
-                    text = "后灯",
-                    isOn = backOn,
-                    enabled = connected
-                ) {
-                    viewModel.sendLightControl(ledStatus?.front ?: 0, if (backOn) 0 else 1)
-                }
-            }
-            Spacer(Modifier.height(4.dp))
-
-            // 充电
-            SectionLabel("充电")
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("开始充电") { viewModel.sendChargeControl(1) }
-                MiniButton("结束充电") { viewModel.sendChargeControl(0) }
-            }
-            Spacer(Modifier.height(4.dp))
-
-            // 休眠
-            SectionLabel("休眠")
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("进入休眠") { viewModel.sendSleepSettings(true) }
-                MiniButton("唤醒") { viewModel.sendSleepSettings(false) }
-            }
-        }
-    }
-}
-
-@Composable
-private fun ControlButton(
-    text: String,
-    enabled: Boolean = true,
-    onClick: () -> Unit
-) {
-    Button(
-        onClick = onClick,
-        enabled = enabled,
-        colors = ButtonDefaults.buttonColors(
-            containerColor = Color(0x66333333),
-            disabledContainerColor = Color(0x33222222)
-        ),
-        modifier = Modifier.width(110.dp)
-    ) {
-        Text(text, color = if (enabled) OverlayText else Color(0x88FFFFFF), fontWeight = FontWeight.Medium)
-    }
-}
-
-@Composable
-private fun MiniButton(text: String, enabled: Boolean = true, onClick: () -> Unit) {
-    Button(
-        onClick = onClick,
-        enabled = enabled,
-        colors = ButtonDefaults.buttonColors(
-            containerColor = Color(0x66333333),
-            disabledContainerColor = Color(0x33222222)
-        ),
-        contentPadding = ButtonDefaults.TextButtonContentPadding,
-        modifier = Modifier.height(32.dp)
-    ) {
-        Text(
-            text,
-            color = if (enabled) OverlayText else Color(0x88FFFFFF),
-            fontSize = 12.sp,
-            fontWeight = FontWeight.Normal
-        )
-    }
-}
-
 @Composable
 private fun LightToggleButton(
     text: String,
@@ -552,40 +505,309 @@ private fun LightToggleButton(
     Button(
         onClick = onClick,
         enabled = enabled,
+        shape = ParallelogramShape(skewLeft = false),
         colors = ButtonDefaults.buttonColors(
             containerColor = if (isOn) Color(0xCCFFC107) else Color(0x66333333),
             disabledContainerColor = Color(0x33222222)
         ),
-        modifier = Modifier.width(110.dp)
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = Modifier.height(32.dp)
     ) {
         Text(
             "$text ${if (isOn) "开" else "关"}",
             color = if (enabled) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
             fontWeight = FontWeight.Medium
         )
     }
 }
 
 @Composable
-private fun SectionLabel(text: String) {
+private fun StandToggleButton(
+    motionState: Int,
+    connected: Boolean,
+    onToggle: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    val isStanding = motionState == ControlCommands.MOTION_STAND ||
+            motionState == ControlCommands.MOTION_RL_CONTROL
+    Button(
+        onClick = onToggle,
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = true),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isStanding) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = modifier.height(32.dp)
+    ) {
         Text(
-        text,
+            text = if (isStanding) "趴下" else "起立",
-        color = Color(0xFFB0B0B0),
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
-        fontSize = 11.sp,
+            fontSize = 12.sp,
-        modifier = Modifier.fillMaxWidth()
+            fontWeight = FontWeight.Medium
         )
     }
+}
+
+// ==================== 模式选择器（3个互斥无缝隙） ====================
+
+@Composable
+private fun ModeSelector(
+    currentMode: Int,
+    connected: Boolean,
+    onSelectMode: (Int) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Row(
+        modifier = modifier,
+        horizontalArrangement = Arrangement.spacedBy(4.dp)
+    ) {
+        ModeButton("常规", ControlCommands.MODE_NORMAL, currentMode, connected, onSelectMode)
+        ModeButton("导航", ControlCommands.MODE_NAVIGATION, currentMode, connected, onSelectMode)
+        ModeButton("辅助", ControlCommands.MODE_ASSIST, currentMode, connected, onSelectMode)
+    }
+}
 
 @Composable
-private fun Separator() {
+private fun ModeButton(
-    Spacer(Modifier.height(2.dp))
+    text: String,
-    Box(
+    mode: Int,
-        modifier = Modifier
+    currentMode: Int,
-            .width(80.dp)
+    connected: Boolean,
-            .height(1.dp)
+    onClick: (Int) -> Unit
-            .background(Color(0x44FFFFFF))
+) {
+    val isActive = currentMode == mode
+    Button(
+        onClick = { onClick(mode) },
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = true),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isActive) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = Modifier.height(32.dp)
+    ) {
+        Text(
+            text,
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = if (isActive) FontWeight.Bold else FontWeight.Normal
         )
-    Spacer(Modifier.height(2.dp))
+    }
+}
+
+// ==================== 步态切换（4个互斥无缝隙，仅普通模式可用） ====================
+
+@Composable
+private fun GaitSelector(
+    currentGait: Int,
+    enabled: Boolean,
+    onSelectGait: (Int) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Row(
+        modifier = modifier,
+        horizontalArrangement = Arrangement.spacedBy(4.dp)
+    ) {
+        GaitButton("基础", ControlCommands.GAIT_BASIC, currentGait, enabled, onSelectGait)
+        GaitButton("楼梯", ControlCommands.GAIT_STAIRS, currentGait, enabled, onSelectGait)
+        GaitButton("平地敏捷", ControlCommands.GAIT_FLAT_AGILE, currentGait, enabled, onSelectGait)
+        GaitButton("楼梯敏捷", ControlCommands.GAIT_STAIRS_AGILE, currentGait, enabled, onSelectGait)
+    }
+}
+
+@Composable
+private fun GaitButton(
+    text: String,
+    gait: Int,
+    currentGait: Int,
+    enabled: Boolean,
+    onClick: (Int) -> Unit
+) {
+    val isActive = currentGait == gait
+    Button(
+        onClick = { onClick(gait) },
+        enabled = enabled,
+        shape = ParallelogramShape(skewLeft = true),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isActive) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = Modifier.height(32.dp)
+    ) {
+        Text(
+            text,
+            color = if (enabled) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = if (isActive) FontWeight.Bold else FontWeight.Normal
+        )
+    }
+}
+
+// ==================== 休眠/唤醒切换 ====================
+
+@Composable
+private fun SleepToggleButton(
+    isSleeping: Boolean,
+    connected: Boolean,
+    onToggle: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Button(
+        onClick = onToggle,
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = false),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isSleeping) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = modifier.height(32.dp)
+    ) {
+        Text(
+            text = if (isSleeping) "唤醒" else "休眠",
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = FontWeight.Medium
+        )
+    }
+}
+
+// ==================== 充电/结束充电切换 ====================
+
+@Composable
+private fun ChargeToggleButton(
+    isCharging: Boolean,
+    connected: Boolean,
+    onToggle: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Button(
+        onClick = onToggle,
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = false),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isCharging) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = modifier.height(32.dp)
+    ) {
+        Text(
+            text = if (isCharging) "充电中" else "充电",
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = FontWeight.Medium
+        )
+    }
+}
+
+// ==================== 软急停滑块 ====================
+
+/**
+ * 水平滑块，平行四边形风格。用于触发软急停。
+ *
+ * 滑到右侧 → 发送软急停指令；滑到左侧 → 仅 UI 复位，不发指令。
+ * 机器人收到软急停后 3 秒自动切回空闲，状态上报会驱动滑块自动归位。
+ *
+ * @param isEmergencyStop 当前是否处于软急停状态（motionState == MOTION_DAMPING）
+ * @param connected 是否已连接（未连接时禁用交互）
+ * @param onEmergencyStop 滑块滑到右侧触发
+ */
+@Composable
+private fun EmergencyStopSlider(
+    isEmergencyStop: Boolean,
+    connected: Boolean,
+    onEmergencyStop: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    val sliderWidth = 150.dp
+    val sliderHeight = 32.dp
+    val thumbSize = 28.dp
+
+    // 0f = 左侧（正常），1f = 右侧（急停触发）
+    var fraction by remember { mutableStateOf(if (isEmergencyStop) 1f else 0f) }
+    var isDragging by remember { mutableStateOf(false) }
+
+    // 非拖动时跟随外部状态回调
+    LaunchedEffect(isEmergencyStop) {
+        if (!isDragging) {
+            fraction = if (isEmergencyStop) 1f else 0f
+        }
+    }
+
+    // 拖动结束后吸附：滑到右侧触发急停，滑到左侧仅复位 UI
+    fun snapAndFire() {
+        isDragging = false
+        if (fraction > 0.5f) {
+            fraction = 1f
+            onEmergencyStop()
+        } else {
+            fraction = 0f
+            // 不发送复位指令，等机器人状态上报自动同步
+        }
+    }
+
+    // 滑轨：遵循其他按钮的 containerColor 逻辑
+    val trackColor = if (connected) Color(0x66333333) else Color(0x33222222)
+    // 拇指：75% 红色
+    val thumbColor = Color(0xBFFF4444)
+    val skew = 3.dp
+
+    Box(
+        modifier = modifier
+            .width(sliderWidth)
+            .height(sliderHeight)
+    ) {
+        // 滑轨 — 平行四边形外框
+        Surface(
+            modifier = Modifier
+                .fillMaxSize(),
+            shape = ParallelogramShape(skewDp = skew, skewLeft = false),
+            color = trackColor
+        ) {}
+
+        // 文字显示在滑轨上
+        Text(
+            text = "急停",
+            modifier = Modifier.align(Alignment.Center),
+            color = Color(0xAAFFFFFF),
+            fontSize = 12.sp,
+            fontWeight = FontWeight.Medium
+        )
+
+        // 滑块拇指
+        val maxOffsetDp = sliderWidth - thumbSize
+        val density = LocalDensity.current
+        val maxOffsetPx = with(density) { maxOffsetDp.toPx() }
+        val thumbOffset = maxOffsetDp * fraction
+        // fraction=0 → offset=0 (左侧)
+        // fraction=1 → offset=maxOffsetDp (右侧)
+
+        Surface(
+            modifier = Modifier
+                .size(thumbSize, sliderHeight)
+                .offset(x = thumbOffset)
+                .pointerInput(connected) {
+                    if (!connected) return@pointerInput
+                    detectHorizontalDragGestures(
+                        onDragStart = { isDragging = true },
+                        onDragEnd = { snapAndFire() },
+                        onDragCancel = { snapAndFire() },
+                        onHorizontalDrag = { change, dragAmount ->
+                            change.consume()
+                            fraction = (fraction + dragAmount / maxOffsetPx).coerceIn(0f, 1f)
+                        }
+                    )
+                },
+            shape = ParallelogramShape(skewDp = skew, skewLeft = false),
+            color = thumbColor
+        ) {}
+    }
 }
 
 // ==================== 辅助函数 ====================

app/src/main/java/com/example/m20_gamepad/ui/MainViewModel.kt

@@ -292,6 +292,15 @@ class MainViewModel(
         client?.sendCommandBlocking(ControlCommands.chargeControl(charge))
     }
 
+    /** 软急停：进入关节阻尼状态。 */
+    fun sendEmergencyStop() {
+        if (robot.canSendMotionControl) {
+            client?.sendCommandBlocking(ControlCommands.softEmergencyStop())
+        } else {
+            _actionFeedback.value = "未连接，无法发送软急停"
+        }
+    }
+
     fun sendSleepSettings(sleep: Boolean, auto: Boolean = false, timeMinutes: Int = 5) {
         client?.sendCommandBlocking(
             ControlCommands.sleepSettings(sleep, auto, timeMinutes)