diff --git a/app/src/main/java/com/ai/assistance/operit/core/tools/defaultTool/standard/StandardChatManagerTool.kt b/app/src/main/java/com/ai/assistance/operit/core/tools/defaultTool/standard/StandardChatManagerTool.kt
index 9b5a01a745..26ee644999 100644
--- a/app/src/main/java/com/ai/assistance/operit/core/tools/defaultTool/standard/StandardChatManagerTool.kt
+++ b/app/src/main/java/com/ai/assistance/operit/core/tools/defaultTool/standard/StandardChatManagerTool.kt
@@ -88,6 +88,26 @@ sealed class MessageSendStreamStartResult {
     data class Failed(val result: ToolResult) : MessageSendStreamStartResult()
 }
 
+/**
+ * 定向发送时，决定悬浮窗应跟随哪个对话显示。
+ *
+ * FLOATING runtime 的 currentChatId 由 ChatRuntimeHolder 从主界面同步而来，只用 chatIdOverride
+ * 发送会让消息进到目标对话、窗口却停在前台对话上。MAIN runtime 不做切换，否则后台发送会把用户
+ * 正在看的对话顶掉。
+ */
+internal object FloatingDisplayChatSelector {
+    fun select(
+        runtimeSlot: ChatRuntimeSlot,
+        targetChatId: String?,
+        displayedChatId: String?
+    ): String? {
+        if (runtimeSlot != ChatRuntimeSlot.FLOATING) return null
+        if (targetChatId.isNullOrBlank()) return null
+        if (targetChatId == displayedChatId) return null
+        return targetChatId
+    }
+}
+
 /**
  * 对话管理工具
  * 负责管理对话、浮窗服务，以及按指定 runtime 发送消息
@@ -1733,7 +1753,8 @@ class StandardChatManagerTool(private val context: Context) {
                 )
             }
 
-            val core = chatRuntimeHolder.getCore(runtimeSlot ?: ChatRuntimeSlot.FLOATING)
+            val effectiveSlot = runtimeSlot ?: ChatRuntimeSlot.FLOATING
+            val core = chatRuntimeHolder.getCore(effectiveSlot)
 
             val message = tool.parameters.find { it.name == "message" }?.value
             if (message.isNullOrBlank()) {
@@ -1892,7 +1913,18 @@ class StandardChatManagerTool(private val context: Context) {
                 }
 
                 if (hasTargetChat) {
-                    // 后台发送到指定对话，不切换 UI
+                    // 悬浮窗跟随目标对话：chatIdOverride 只路由消息，FLOATING runtime 的
+                    // currentChatId 仍停在前台对话上，窗口会显示错误的会话（#555）。
+                    // switchChatLocal 只改悬浮窗本地状态，不写回全局，主界面不受影响。
+                    FloatingDisplayChatSelector.select(
+                        runtimeSlot = effectiveSlot,
+                        targetChatId = targetChatId,
+                        displayedChatId = core.currentChatId.value
+                    )?.let { chatToFollow ->
+                        core.switchChatLocal(chatToFollow)
+                    }
+
+                    // 后台发送到指定对话，不切换主界面
                     core.sendUserMessage(
                         promptFunctionType = PromptFunctionType.CHAT,
                         roleCardIdOverride = roleCardId,
diff --git a/app/src/test/java/com/ai/assistance/operit/core/tools/defaultTool/standard/FloatingDisplayChatSelectorTest.kt b/app/src/test/java/com/ai/assistance/operit/core/tools/defaultTool/standard/FloatingDisplayChatSelectorTest.kt
new file mode 100644
index 0000000000..1c79311b8c
--- /dev/null
+++ b/app/src/test/java/com/ai/assistance/operit/core/tools/defaultTool/standard/FloatingDisplayChatSelectorTest.kt
@@ -0,0 +1,96 @@
+package com.ai.assistance.operit.core.tools.defaultTool.standard
+
+import com.ai.assistance.operit.api.chat.ChatRuntimeSlot
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class FloatingDisplayChatSelectorTest {
+
+    @Test
+    fun select_floatingRuntimeFollowsWorkflowTargetChatInsteadOfForegroundChat() {
+        // #555: a workflow sends to chat B while the user is looking at chat A.
+        val result =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.FLOATING,
+                targetChatId = "chat-b",
+                displayedChatId = "chat-a"
+            )
+
+        assertEquals("chat-b", result)
+    }
+
+    @Test
+    fun select_floatingRuntimeFollowsTargetWhenNothingIsDisplayedYet() {
+        val result =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.FLOATING,
+                targetChatId = "chat-b",
+                displayedChatId = null
+            )
+
+        assertEquals("chat-b", result)
+    }
+
+    @Test
+    fun select_mainRuntimeNeverSwitchesAwayFromForegroundChat() {
+        val result =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.MAIN,
+                targetChatId = "chat-b",
+                displayedChatId = "chat-a"
+            )
+
+        assertNull(result)
+    }
+
+    @Test
+    fun select_returnsNullWhenTargetAlreadyDisplayed() {
+        val result =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.FLOATING,
+                targetChatId = "chat-a",
+                displayedChatId = "chat-a"
+            )
+
+        assertNull(result)
+    }
+
+    @Test
+    fun select_returnsNullWhenNoTargetChatIsGiven() {
+        val floating =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.FLOATING,
+                targetChatId = null,
+                displayedChatId = "chat-a"
+            )
+        val main =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.MAIN,
+                targetChatId = null,
+                displayedChatId = "chat-a"
+            )
+
+        assertNull(floating)
+        assertNull(main)
+    }
+
+    @Test
+    fun select_returnsNullWhenTargetChatIsBlank() {
+        val blank =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.FLOATING,
+                targetChatId = "   ",
+                displayedChatId = "chat-a"
+            )
+        val empty =
+            FloatingDisplayChatSelector.select(
+                runtimeSlot = ChatRuntimeSlot.FLOATING,
+                targetChatId = "",
+                displayedChatId = "chat-a"
+            )
+
+        assertNull(blank)
+        assertNull(empty)
+    }
+}
diff --git a/docs/doc-src/package-dev/chat.md b/docs/doc-src/package-dev/chat.md
index 6171a72880..2c45912505 100644
--- a/docs/doc-src/package-dev/chat.md
+++ b/docs/doc-src/package-dev/chat.md
@@ -103,6 +103,7 @@ findChat({ query, match?, index? }): Promise<ChatFindResultData>
 其中：
 
 - `runtime` 用于指定本次消息发送到哪个 chat runtime，未指定时默认走 `floating`
+- 传入 `chatId` 时消息只投递到该对话，走 `floating` 时悬浮窗会一并切到该对话显示，走 `main` 时不切换用户正在看的对话
 - `timeout_ms` 用于控制本次发送的最长等待时间，单位毫秒
 
 ### `call(options)`