fix(chat): continue external-writer conversations through desktop owner

README.md

@@ -107,6 +107,10 @@ adb install -r app/build/outputs/apk/debug/app-debug.apk
 
 ## 连接异常排查
 
+若会话被其他 Codex 客户端占用，Android 会以 external-writer 模式查看并自动更新原会话历史。可选的 [Desktop companion](companion/README.md) 支持将文字交给持有原会话的电脑客户端，避免另建对话；当前为实验功能，需要独立部署伴随代理。
+
+同步时直接更新最新回合的完整处理过程；历史回合的详情按需加载并保留缓存。同一服务端摘要不会因为详情中多了中间回复而反复重置加载状态。
+
 生产版本通过 Logcat 的 `CodexConnection` 标签记录连接失败、非主动断开、请求超时和会话恢复失败，正常连接、消息收发和主动取消不记录
 
 ```bash

app/build.gradle.kts

@@ -1,3 +1,8 @@
+import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.tasks.Classpath
+import org.gradle.api.tasks.testing.Test
+import org.gradle.process.CommandLineArgumentProvider
+
 plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.kotlin.compose)
@@ -6,6 +11,21 @@ plugins {
     alias(libs.plugins.room)
 }
 
+val mockitoAgent = configurations.create("mockitoAgent")
+
+abstract class MockitoAgentProvider : CommandLineArgumentProvider {
+    @get:Classpath
+    abstract val agentJar: ConfigurableFileCollection
+
+    override fun asArguments(): List<String> = listOf("-javaagent:${agentJar.asPath}")
+}
+
+tasks.withType<Test>().configureEach {
+    jvmArgumentProviders.add(objects.newInstance<MockitoAgentProvider>().apply {
+        agentJar.from(mockitoAgent)
+    })
+}
+
 val releaseSigningEnabled = providers.gradleProperty("releaseSigning").orNull == "true"
 
 fun requiredSigningEnvironmentVariable(name: String): String =
@@ -102,6 +122,8 @@ dependencies {
     debugImplementation(libs.androidx.compose.ui.tooling)
 
     testImplementation(libs.junit)
+    testImplementation(libs.mockito.core)
+    mockitoAgent(libs.mockito.core) { isTransitive = false }
     testImplementation(libs.kotlinx.coroutines.test)
 
     ksp(libs.androidx.room.compiler)

app/src/main/java/com/hebo/codex/data/remote/AppServerApi.kt

@@ -160,6 +160,7 @@ class AppServerApi(
         StableRpcMethod.THREAD_READ,
         buildJsonObject {
             put("threadId", threadId)
+            put("includeTurns", false)
         },
     ).jsonObject
 
@@ -213,6 +214,39 @@ class AppServerApi(
         timeoutMillis = input.submissionTimeoutMillis(),
     ).jsonObject
 
+    // Optional codex-android companion extension, separate from Codex CLI RPCs.
+    suspend fun discoverDesktopControl(threadId: String): Boolean = try {
+        val result = connection.request(
+            "codexAndroid/desktop/discover",
+            buildJsonObject { put("threadId", threadId) },
+        ).jsonObject
+        if (result.requiredString("threadId") != threadId || result.requiredInt("protocolVersion") != 1) {
+            throw ProtocolException("电脑伴随服务的会话或协议不匹配")
+        }
+        result.requiredBoolean("available")
+    } catch (error: RpcException) {
+        val unsupported = error.code == -32601 || (error.code == -32600 &&
+            error.message.startsWith("Invalid request: unknown variant `codexAndroid/desktop/discover`"))
+        if (!unsupported) throw error
+        false
+    }
+
+    suspend fun sendDesktopMessage(threadId: String, clientMessageId: String, text: String): JsonObject =
+        connection.request(
+            "codexAndroid/desktop/turn/start",
+            buildJsonObject {
+                put("threadId", threadId)
+                put("clientUserMessageId", clientMessageId)
+                put("text", text)
+            },
+            timeoutMillis = 120_000,
+        ).jsonObject.also { result ->
+            if (result.requiredString("threadId") != threadId ||
+                result.requiredString("clientUserMessageId") != clientMessageId
+            ) throw ProtocolException("电脑端的发送确认与当前消息不一致")
+            result.requiredObject("turn").requiredString("id")
+        }
+
     suspend fun steerTurn(
         threadId: String,
         turnId: String,