fix(app): 停止实例按实例 id 找 pid，并发启动不再杀错进程树

reviewer-guiwire r1 的 P2-1：`running_pid` 只记「最近一次启动」的单槽 pid，
并发启动 A、B 后点 A 的停止键会 tree_kill 掉 B；且实时尾随在 B 启动时被抢占，
A 的日志再也没人跟。兜底分支也永远不命中（`game::instances` 每次重建都把
runtime 置 Idle）。

改法：
- 单槽 `launch_pid` → `launches: Vec<LiveLaunch{instance, session, pid}>`，
  停止/收尾/尾随判定都按实例 id 或会话 id 精确匹配；
- 同一实例重复点启动直接拒绝（「已经在启动/运行中」），不再起第二个进程；
- 收尾只拆自己那场的尾随，并发时另一实例的实时日志不被掐断；
- 实时尾随仍是单窗口（一次只跟一场，另一场收尾后可从 JSONL 回放）——这是
  有意的 UI 取舍，不是漏判。

crates/app/src/host/handle.rs

@@ -0,0 +1,134 @@
+//! `HostTask` → `CoreEvent` 的翻译（从 `host/mod.rs` 拆出，守 400 行硬限）。
+//!
+//! 父模块的私有字段对子模块可见，所以这里直接读写 `self.tx` / `self.launches` 等。
+
+use crate::dto::{AppEvent, CoreEvent, InstanceRuntime, LogOutcome};
+use crate::toast::ToastKind;
+
+use super::{logs, CoreHost, HostTask, LiveLaunch};
+
+impl CoreHost {
+    /// 后台消息 → 事件。
+    pub(super) fn handle(&mut self, task: HostTask) {
+        match task {
+            HostTask::Versions(Ok(versions)) => self.send(CoreEvent::VersionListChanged(versions)),
+            HostTask::Versions(Err(reason)) => {
+                self.toast(ToastKind::Warn, format!("拉取版本清单失败：{reason}"));
+            }
+            HostTask::Install(progress) => {
+                self.install = Some(*progress.clone());
+                self.send(CoreEvent::InstallProgress(Some(*progress)));
+            }
+            HostTask::InstallDone { progress, result } => {
+                self.install_cancel = None;
+                self.install = Some(*progress.clone());
+                self.send(CoreEvent::InstallProgress(Some(*progress)));
+                match result {
+                    Ok(_) => {
+                        self.refresh_instances();
+                        self.send(CoreEvent::LogSessionsChanged(logs::sessions(&self.env)));
+                    }
+                    Err(reason) => self.toast(ToastKind::Error, reason),
+                }
+            }
+            HostTask::Accounts(accounts) => {
+                self.accounts = accounts.clone();
+                self.send(CoreEvent::AccountsChanged(accounts));
+                self.refresh_instances();
+            }
+            HostTask::Login(view) => self.send(CoreEvent::DeviceLoginChanged(*view)),
+            HostTask::Java(page) => self.send(CoreEvent::JavaChanged(*page)),
+            HostTask::Logs {
+                sessions,
+                lines,
+                diagnosis,
+            } => {
+                self.send(CoreEvent::LogSessionsChanged(sessions));
+                self.send(CoreEvent::LogLinesChanged(lines));
+                if let Some(report) = diagnosis {
+                    self.send(CoreEvent::DiagnosisReady(report));
+                }
+            }
+            HostTask::Sessions(sessions) => self.send(CoreEvent::LogSessionsChanged(sessions)),
+            HostTask::Tail(batch) => {
+                if batch.running {
+                    self.send(CoreEvent::LogLinesChanged(batch.lines));
+                } else {
+                    self.send(CoreEvent::LogAppended(*batch));
+                }
+            }
+            HostTask::LaunchStarted {
+                id,
+                session_id,
+                pid,
+            } => {
+                self.launches.retain(|live| live.instance != id);
+                self.launches.push(LiveLaunch {
+                    instance: id.clone(),
+                    session: session_id.clone(),
+                    pid,
+                });
+                // 实时尾随一次只跟一场（下载页/日志页共用一个滚动窗口）；
+                // 已有别的实例在尾随时不抢占——它的日志仍在 JSONL 里，收尾后可回放。
+                if self.tail.session().is_none() {
+                    self.tail.attach(
+                        self.env
+                            .sessions_root()
+                            .join("game")
+                            .join(format!("{session_id}.jsonl")),
+                        &session_id,
+                    );
+                }
+                self.send(CoreEvent::InstanceRuntimeChanged {
+                    id,
+                    runtime: InstanceRuntime::Running { pid },
+                });
+            }
+            HostTask::Runtime { id, runtime } => {
+                self.send(CoreEvent::InstanceRuntimeChanged { id, runtime });
+            }
+            HostTask::LaunchEnd(finished) => {
+                self.launches.retain(|live| live.instance != finished.id);
+                let runtime = if finished.outcome == LogOutcome::Ok {
+                    InstanceRuntime::Idle
+                } else {
+                    InstanceRuntime::Failed {
+                        reason: finished.summary.clone(),
+                    }
+                };
+                self.send(CoreEvent::InstanceRuntimeChanged {
+                    id: finished.id.clone(),
+                    runtime,
+                });
+                self.send(CoreEvent::LaunchFinished((*finished).clone()));
+                // 只拆自己那场的尾随：并发时另一实例的实时日志不该被这次收尾掐掉。
+                if self.tail.session() == Some(finished.session.as_str()) {
+                    self.tail.detach();
+                }
+                self.send(CoreEvent::LogSessionsChanged(logs::sessions(&self.env)));
+                self.refresh_instances();
+            }
+            HostTask::Crash(report) => {
+                self.send(CoreEvent::DiagnosisReady(*report));
+            }
+            HostTask::Notice(notice) => self.push_notice(*notice),
+            HostTask::Toast(toast) => self.events.push_back(AppEvent::Toast(*toast)),
+        }
+    }
+
+    /// 尾随运行中会话（每 `TAIL_POLL_TICKS` 拍一次）。
+    pub(super) fn poll_tail(&mut self) {
+        let Some((session, lines)) = self.tail.poll() else {
+            return;
+        };
+        if lines.is_empty() {
+            return;
+        }
+        let running = self.launches.iter().any(|live| live.session == session);
+        self.send(CoreEvent::LogAppended(crate::dto::LiveLogBatch {
+            session,
+            lines,
+            running,
+        }));
+    }
+}

crates/app/src/host/mod.rs

@@ -17,6 +17,7 @@ mod dispatch;
 mod engine;
 pub mod env;
 mod game;
+mod handle;
 mod identity;
 mod install;
 mod java;
@@ -32,7 +33,7 @@ use std::time::Duration;
 
 use crate::dto::{
     AccountView, AppCommand, AppEvent, Backend, CoreEvent, DiagnosisReport, InstallProgressView,
-    InstanceRuntime, JavaChainStep, LogOutcome, NoticeView,
+    InstanceRuntime, JavaChainStep, NoticeView,
 };
 use crate::mock::MockBackend;
 use crate::toast::{Toast, ToastKind};
@@ -47,6 +48,14 @@ const MAX_TASKS_PER_TICK: usize = 64;
 /// 实时日志尾随间隔（拍数，33ms/拍 → 约 600ms 一次）。
 const TAIL_POLL_TICKS: u64 = 18;
 
+/// 一次在跑的启动（并发启动时按实例 id 区分，停止/尾随都不会串到别的实例）。
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct LiveLaunch {
+    instance: String,
+    session: String,
+    pid: u32,
+}
+
 /// 真实 host。
 pub struct CoreHost {
     env: HostEnv,
@@ -63,8 +72,8 @@ pub struct CoreHost {
     java_message: String,
     install: Option<InstallProgressView>,
     notices: Vec<NoticeView>,
-    /// 最近一次启动的 pid（停止按钮用）
-    launch_pid: Option<u32>,
+    /// 在跑的启动（实例 → 会话 → pid；支持多个实例同时启动，停止按 id 找正确的 pid）
+    launches: Vec<LiveLaunch>,
     /// 实时日志尾随器
     tail: logs::Tail,
     /// AI 对话的临时后端（agent GUI host 落地前的占位）
@@ -97,7 +106,7 @@ impl CoreHost {
             java_message: String::new(),
             install: None,
             notices: Vec::new(),
-            launch_pid: None,
+            launches: Vec::new(),
             tail: logs::Tail::default(),
             chat: MockBackend::default(),
             install_cancel: None,
@@ -202,6 +211,14 @@ impl CoreHost {
             return;
         };
         let instance_id = target.id.clone();
+        if self
+            .launches
+            .iter()
+            .any(|live| live.instance == instance_id)
+        {
+            self.toast(ToastKind::Warn, "这个实例已经在启动/运行中");
+            return;
+        }
         if let Some(notice) = game::mode_change_notice(&self.env, &instance_id) {
             self.push_notice(notice);
         }
@@ -215,10 +232,13 @@ impl CoreHost {
         launch::start(self.env.clone(), self.tx.clone(), target);
     }
 
-    /// 一台在跑的实例的 pid（从快照或最近一次启动里取）。
+    /// 某实例在跑的 pid（按实例 id 查启动表；不再有「最近一次启动」这种单槽）。
+    ///
+    /// 兜底分支读实例快照的 `Running { pid }`：host 自己发的运行时事件会写回快照，
+    /// 但快照是重建的（`game::instances` 每次 Idle），所以这层只是给将来留的口。
     fn running_pid(&self, id: &str) -> Option<u32> {
-        if let Some(pid) = self.launch_pid {
-            return Some(pid);
+        if let Some(live) = self.launches.iter().find(|live| live.instance == id) {
+            return Some(live.pid);
         }
         game::instances(&self.env)
             .into_iter()
@@ -228,118 +248,6 @@ impl CoreHost {
                 _ => None,
             })
     }
-
-    /// 后台消息 → 事件。
-    fn handle(&mut self, task: HostTask) {
-        match task {
-            HostTask::Versions(Ok(versions)) => self.send(CoreEvent::VersionListChanged(versions)),
-            HostTask::Versions(Err(reason)) => {
-                self.toast(ToastKind::Warn, format!("拉取版本清单失败：{reason}"));
-            }
-            HostTask::Install(progress) => {
-                self.install = Some(*progress.clone());
-                self.send(CoreEvent::InstallProgress(Some(*progress)));
-            }
-            HostTask::InstallDone { progress, result } => {
-                self.install_cancel = None;
-                self.install = Some(*progress.clone());
-                self.send(CoreEvent::InstallProgress(Some(*progress)));
-                match result {
-                    Ok(_) => {
-                        self.refresh_instances();
-                        self.send(CoreEvent::LogSessionsChanged(logs::sessions(&self.env)));
-                    }
-                    Err(reason) => self.toast(ToastKind::Error, reason),
-                }
-            }
-            HostTask::Accounts(accounts) => {
-                self.accounts = accounts.clone();
-                self.send(CoreEvent::AccountsChanged(accounts));
-                self.refresh_instances();
-            }
-            HostTask::Login(view) => self.send(CoreEvent::DeviceLoginChanged(*view)),
-            HostTask::Java(page) => self.send(CoreEvent::JavaChanged(*page)),
-            HostTask::Logs {
-                sessions,
-                lines,
-                diagnosis,
-            } => {
-                self.send(CoreEvent::LogSessionsChanged(sessions));
-                self.send(CoreEvent::LogLinesChanged(lines));
-                if let Some(report) = diagnosis {
-                    self.send(CoreEvent::DiagnosisReady(report));
-                }
-            }
-            HostTask::Sessions(sessions) => self.send(CoreEvent::LogSessionsChanged(sessions)),
-            HostTask::Tail(batch) => {
-                if batch.running {
-                    self.send(CoreEvent::LogLinesChanged(batch.lines));
-                } else {
-                    self.send(CoreEvent::LogAppended(*batch));
-                }
-            }
-            HostTask::LaunchStarted {
-                id,
-                session_id,
-                pid,
-            } => {
-                self.launch_pid = Some(pid);
-                self.tail.attach(
-                    self.env
-                        .sessions_root()
-                        .join("game")
-                        .join(format!("{session_id}.jsonl")),
-                    &session_id,
-                );
-                self.send(CoreEvent::InstanceRuntimeChanged {
-                    id,
-                    runtime: InstanceRuntime::Running { pid },
-                });
-            }
-            HostTask::Runtime { id, runtime } => {
-                self.send(CoreEvent::InstanceRuntimeChanged { id, runtime });
-            }
-            HostTask::LaunchEnd(finished) => {
-                self.launch_pid = None;
-                let runtime = if finished.outcome == LogOutcome::Ok {
-                    InstanceRuntime::Idle
-                } else {
-                    InstanceRuntime::Failed {
-                        reason: finished.summary.clone(),
-                    }
-                };
-                self.send(CoreEvent::InstanceRuntimeChanged {
-                    id: finished.id.clone(),
-                    runtime,
-                });
-                self.send(CoreEvent::LaunchFinished((*finished).clone()));
-                self.tail.detach();
-                self.send(CoreEvent::LogSessionsChanged(logs::sessions(&self.env)));
-                self.refresh_instances();
-            }
-            HostTask::Crash(report) => {
-                self.send(CoreEvent::DiagnosisReady(*report));
-            }
-            HostTask::Notice(notice) => self.push_notice(*notice),
-            HostTask::Toast(toast) => self.events.push_back(AppEvent::Toast(*toast)),
-        }
-    }
-
-    /// 尾随运行中会话（每 `TAIL_POLL_TICKS` 拍一次）。
-    fn poll_tail(&mut self) {
-        let Some((session, lines)) = self.tail.poll() else {
-            return;
-        };
-        if lines.is_empty() {
-            return;
-        }
-        let running = self.launch_pid.is_some();
-        self.send(CoreEvent::LogAppended(crate::dto::LiveLogBatch {
-            session,
-            lines,
-            running,
-        }));
-    }
 }
 
 impl Backend for CoreHost {