diff --git a/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt b/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt
index 9e91a1b2..60342471 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt
@@ -38,6 +38,7 @@ import androidx.compose.material.icons.filled.Add
 import androidx.compose.material.icons.filled.Close
 import androidx.compose.material.icons.filled.Search
 import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Button
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -911,6 +912,25 @@ fun ChatScreen(
             )
         }
 
+        // Expensive / Data-policy model confirmation dialog (issue #589 follow-up)
+        if (state.modelSwitchConfirmMessage != null) {
+            AlertDialog(
+                onDismissRequest = { viewModel.dismissModelSwitchConfirm() },
+                title = { Text(stringResource(R.string.model_expensive_title)) },
+                text = { Text(state.modelSwitchConfirmMessage!!) },
+                confirmButton = {
+                    Button(onClick = { viewModel.confirmModelSwitchExpensive() }) {
+                        Text(stringResource(R.string.model_confirm_continue))
+                    }
+                },
+                dismissButton = {
+                    TextButton(onClick = { viewModel.dismissModelSwitchConfirm() }) {
+                        Text(stringResource(R.string.common_cancel))
+                    }
+                },
+            )
+        }
+
         if (showContextSheet && state.contextBreakdown != null) {
             ContextDetailSheet(
                 breakdown = state.contextBreakdown!!,
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt b/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt
index 19a29724..10d63fa8 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt
@@ -327,6 +327,7 @@ data class ChatUiState(
     val modelPickerProviders: List<ModelProvider> = emptyList(),
     val modelPickerPinned: List<PinnedModel> = emptyList(),
     val modelPickerLoading: Boolean = false,
+    val modelSwitchConfirmMessage: String? = null,
     // Current session's active model label (provider/model), shown in the chip
     val currentSessionModel: String? = null,
     // Per-model reasoning capabilities for the current session's model
@@ -463,6 +464,15 @@ class ChatViewModel(
 
     private val sessionRequestById = ConcurrentHashMap<String, SessionRequest>()
     private var sessionGeneration = 0L
+
+    private data class ActiveModelSwitch(
+        val spec: String,
+        val previousModel: String?,
+    )
+
+    private val pendingModelSwitchRequests = ConcurrentHashMap<String, ActiveModelSwitch>()
+    private var activeModelSwitchConfirmation: ActiveModelSwitch? = null
+    private var optimisticPreviousModel: String? = null
     private var resumeRequestSequence = 0L
     private var activeResumeRequestSequence = 0L
     private var hydrationRequestSequence = 0L
@@ -1208,6 +1218,25 @@ class ChatViewModel(
                     addSystemMessage("Approval submitted")
                 }
             }
+
+            WsMethods.CONFIG_SET -> {
+                val pending = pendingModelSwitchRequests.remove(id)
+                val map = result as? Map<*, *> ?: return
+                val key = map["key"] as? String
+                if (key == "model") {
+                    val confirmRequired = map["confirm_required"] as? Boolean ?: false
+                    if (confirmRequired) {
+                        val confirmMessage =
+                            (map["confirm_message"] as? String)
+                                ?: (map["warning"] as? String)
+                                ?: "This model requires confirmation to switch. Continue?"
+                        activeModelSwitchConfirmation = pending
+                        _uiState.update {
+                            it.copy(modelSwitchConfirmMessage = confirmMessage)
+                        }
+                    }
+                }
+            }
         }
     }
 
@@ -1889,7 +1918,10 @@ class ChatViewModel(
      *   `<model> --provider <slug> --session`
      * (matching the TUI client's `modelValueForConfigSet`).
      */
-    private fun handleModelSwitch(command: String) {
+    private fun handleModelSwitch(
+        command: String,
+        confirmExpensive: Boolean = false,
+    ) {
         val sessionId = runtimeSessionId
         if (sessionId == null) {
             addAssistantMessage("No active session. Use `/new` to create one.")
@@ -1906,11 +1938,25 @@ class ChatViewModel(
             } else {
                 command.trim()
             }
+        val previousModel = optimisticPreviousModel ?: _uiState.value.currentSessionModel
+        optimisticPreviousModel = null
+        val params =
+            mutableMapOf<String, Any>(
+                "key" to "model",
+                "value" to spec,
+                "session_id" to sessionId,
+            )
+        if (confirmExpensive) {
+            params["confirm_expensive_model"] = true
+        }
         viewModelScope.launch(ioDispatcher) {
             wsClient.send(
                 WsMethods.CONFIG_SET,
-                mapOf("key" to "model", "value" to spec, "session_id" to sessionId),
-                onSent = { id -> trackRequest(id, WsMethods.CONFIG_SET) },
+                params,
+                onSent = { id ->
+                    trackRequest(id, WsMethods.CONFIG_SET)
+                    pendingModelSwitchRequests[id] = ActiveModelSwitch(spec, previousModel)
+                },
             )
         }
     }
@@ -2265,6 +2311,7 @@ class ChatViewModel(
         provider: String,
         model: String,
     ) {
+        optimisticPreviousModel = _uiState.value.currentSessionModel
         _uiState.update {
             it.copy(
                 showModelPicker = false,
@@ -2280,6 +2327,28 @@ class ChatViewModel(
         handleSlashCommand("/model $model --provider $provider --session")
     }
 
+    fun dismissModelSwitchConfirm() {
+        val pending = activeModelSwitchConfirmation
+        activeModelSwitchConfirmation = null
+        _uiState.update {
+            it.copy(
+                modelSwitchConfirmMessage = null,
+                currentSessionModel = pending?.previousModel ?: it.currentSessionModel,
+            )
+        }
+        syncCurrentModelCapabilities()
+        fetchContextUsage()
+    }
+
+    fun confirmModelSwitchExpensive() {
+        val pending = activeModelSwitchConfirmation
+        activeModelSwitchConfirmation = null
+        _uiState.update { it.copy(modelSwitchConfirmMessage = null) }
+        if (pending != null) {
+            handleModelSwitch(pending.spec, confirmExpensive = true)
+        }
+    }
+
     /**
      * Set the reasoning effort level for the current session.
      *
@@ -2575,6 +2644,7 @@ class ChatViewModel(
                 showSessionPicker = false,
                 showModelPicker = false,
                 modelPickerLoading = false,
+                modelSwitchConfirmMessage = null,
                 currentSessionModel = null,
                 currentModelCapabilities = null,
                 reasoningLevel = null,
diff --git a/app/src/main/res/values-ar/strings.xml b/app/src/main/res/values-ar/strings.xml
index 6a82b593..431a54a4 100644
--- a/app/src/main/res/values-ar/strings.xml
+++ b/app/src/main/res/values-ar/strings.xml
@@ -1078,7 +1078,8 @@
 <string name="moa_title">مزيج الوكلاء (Mixture of Agents)</string>
 <string name="model_aux_tasks_label">المهام المساعدة</string>
 <string name="model_aux_tasks_title">المهام المساعدة</string>
-<string name="model_expensive_title">نموذج عالي التكلفة</string>
+<string name="model_expensive_title">نموذج مرتفع التكلفة</string>
+<string name="model_confirm_continue">متابعة</string>
 <string name="model_main_label">النموذج الرئيسي</string>
 <string name="model_moa_label">مزيج الوكلاء (Mixture of Agents)</string>
 <string name="model_new_sessions">ينطبق على الجلسات الجديدة</string>
diff --git a/app/src/main/res/values-ko/strings.xml b/app/src/main/res/values-ko/strings.xml
index 9dd5cf74..ba813670 100644
--- a/app/src/main/res/values-ko/strings.xml
+++ b/app/src/main/res/values-ko/strings.xml
@@ -387,6 +387,7 @@
     <string name="model_no_models">보고된 모델이 없거나 인증이 필요합니다.</string>
     <string name="content_desc_active_model">활성 모델</string>
     <string name="model_section_pinned">고정된 모델</string>
+    <string name="model_confirm_continue">계속</string>
     <string name="content_desc_unpin_model">모델 고정 해제</string>
     <string name="content_desc_pinned_section_toggle">고정 섹션 표시 전환</string>
 
diff --git a/app/src/main/res/values-zh/strings.xml b/app/src/main/res/values-zh/strings.xml
index bdff2ba1..ebd07c23 100644
--- a/app/src/main/res/values-zh/strings.xml
+++ b/app/src/main/res/values-zh/strings.xml
@@ -1069,6 +1069,7 @@
     <string name="moa_title">多 Agent 混合</string>
     <string name="model_aux_tasks_label">辅助任务</string>
     <string name="model_aux_tasks_title">辅助任务</string>
+    <string name="model_confirm_continue">继续</string>
     <string name="model_expensive_title">高成本模型</string>
     <string name="model_main_label">主模型</string>
     <string name="model_moa_label">多 Agent 混合</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index a3113b56..6930444a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1198,6 +1198,7 @@
     <string name="moa_title">Mixture of Agents</string>
     <string name="model_aux_tasks_label">Auxiliary tasks</string>
     <string name="model_aux_tasks_title">Auxiliary Tasks</string>
+    <string name="model_confirm_continue">Continue</string>
     <string name="model_expensive_title">Expensive Model</string>
     <string name="model_main_label">Main model</string>
     <string name="model_moa_label">Mixture of Agents</string>
diff --git a/app/src/test/java/com/m57/hermescontrol/ui/chat/ChatViewModelTest.kt b/app/src/test/java/com/m57/hermescontrol/ui/chat/ChatViewModelTest.kt
index 3df66a2b..c6c3f9ea 100644
--- a/app/src/test/java/com/m57/hermescontrol/ui/chat/ChatViewModelTest.kt
+++ b/app/src/test/java/com/m57/hermescontrol/ui/chat/ChatViewModelTest.kt
@@ -793,6 +793,109 @@ class ChatViewModelTest {
             assertEquals(sessionId, call.third)
         }
 
+    @Test
+    fun testModelSwitch_confirmRequired_triggersConfirmationDialogAndReSends() =
+        runTest {
+            val (viewModel, sessionId) = createViewModelWithSession()
+
+            var lastReqId = ""
+            val capturedParams = mutableListOf<Map<String, Any>>()
+            every { HermesWsClient.send(WsMethods.CONFIG_SET, any(), any()) } answers {
+                val params = arg<Map<String, Any>>(1)
+                capturedParams.add(params)
+                val id = "req-confirm-${capturedParams.size}"
+                lastReqId = id
+                arg<((String) -> Unit)?>(2)?.invoke(id)
+                id
+            }
+
+            // User sends model switch command that triggers privacy/expensive guard
+            viewModel.sendMessage("/model muse-spark-1.3-contributor-free --provider opencode-free --session")
+            advanceUntilIdle()
+
+            assertEquals(1, capturedParams.size)
+            assertNull(capturedParams[0]["confirm_expensive_model"])
+
+            // Backend returns confirm_required = true
+            mockEventsFlow.emit(
+                WsEvent.RpcResult(
+                    id = lastReqId,
+                    result =
+                        mapOf(
+                            "key" to "model",
+                            "value" to "muse-spark-1.3-contributor-free",
+                            "confirm_required" to true,
+                            "confirm_message" to "Meta training warning",
+                        ),
+                ),
+            )
+            advanceUntilIdle()
+
+            // UI state now shows confirmation dialog message
+            assertEquals("Meta training warning", viewModel.uiState.value.modelSwitchConfirmMessage)
+
+            // User confirms
+            viewModel.confirmModelSwitchExpensive()
+            advanceUntilIdle()
+
+            assertNull(viewModel.uiState.value.modelSwitchConfirmMessage)
+            assertEquals(2, capturedParams.size)
+            assertEquals(true, capturedParams[1]["confirm_expensive_model"])
+            assertEquals(
+                "muse-spark-1.3-contributor-free --provider opencode-free --session",
+                capturedParams[1]["value"],
+            )
+            assertEquals(sessionId, capturedParams[1]["session_id"])
+        }
+
+    @Test
+    fun testModelSwitch_dismissConfirmation_revertsModel() =
+        runTest {
+            val (viewModel, _) = createViewModelWithSession()
+
+            var lastReqId = ""
+            every { HermesWsClient.send(WsMethods.CONFIG_SET, any(), any()) } answers {
+                val id = "req-cfg-dismiss"
+                lastReqId = id
+                arg<((String) -> Unit)?>(2)?.invoke(id)
+                id
+            }
+
+            // Set an initial model
+            viewModel.sendSlashModel("openai", "gpt-4o")
+            advanceUntilIdle()
+            assertEquals("openai/gpt-4o", viewModel.uiState.value.currentSessionModel)
+
+            // Switch to expensive model
+            viewModel.sendSlashModel("opencode-free", "muse-spark-1.3-contributor-free")
+            advanceUntilIdle()
+            assertEquals("opencode-free/muse-spark-1.3-contributor-free", viewModel.uiState.value.currentSessionModel)
+
+            // Backend requires confirmation
+            mockEventsFlow.emit(
+                WsEvent.RpcResult(
+                    id = lastReqId,
+                    result =
+                        mapOf(
+                            "key" to "model",
+                            "value" to "muse-spark-1.3-contributor-free",
+                            "confirm_required" to true,
+                            "confirm_message" to "Meta training warning",
+                        ),
+                ),
+            )
+            advanceUntilIdle()
+            assertEquals("Meta training warning", viewModel.uiState.value.modelSwitchConfirmMessage)
+
+            // User dismisses/cancels
+            viewModel.dismissModelSwitchConfirm()
+            advanceUntilIdle()
+
+            assertNull(viewModel.uiState.value.modelSwitchConfirmMessage)
+            // Reverted back to previous model
+            assertEquals("openai/gpt-4o", viewModel.uiState.value.currentSessionModel)
+        }
+
     // ── Connection / init tests ──────────────────────────────────────────────
 
     @Test