fix(session): keep panel ids distinct from session ids so restore rebinds panes

面板 id 曾直接复用 pty 会话 id（`addPanel({ id: sessionId })`），而
`updateParameters` 只能换会话、不能改面板 id。于是恢复时面板 id 指向一个
已不存在的会话：分屏少一个、剩下的 pane 背后没有 pty，界面看起来是空白，
也无法输入。

- 新增 `panelId()`，面板 id 与会话 id 彻底分离，并用于所有建面板处
  （新建终端、SSH 连接、分屏复制）
- 新增 `breakIdCoincidence()`：旧快照仍带 `panelId === sessionId`，
  在 `fromJSON` 之前重写 grid/panels/views/activeView 中的 id，
  返回 old→new 映射
- `rebindSessionPanels` 用该映射回查快照，恢复每个 pane 自己的目录
  （否则新 id 查不到记录，cwd 会静默退回 home）

验证（重启恢复 E2E，legacy 快照 + 2 分屏）：
  2/2 pane 挂载、2 个独立存活会话、输入可回环、
  cwd 分别回到 D:/AIGC/OpenTerminal 与 C:/Windows、回写快照无 id 冲突；
  restoreSession=false 时正确忽略快照只建 1 个终端。

src/shared/api.ts

@@ -5,7 +5,8 @@ import type {
   PtyCreateResult,
   PtyDataEvent,
   PtyExitEvent,
-  SessionOpenResult
+  SessionOpenResult,
+  SessionSnapshot
 } from './ipc'
 import type { AppSettings } from './settings'
 import type { ReleaseNote, UpdateState } from './ipc'
@@ -113,4 +114,12 @@ export interface AppApi {
   updateInstall(): Promise<void>
   updateChangelog(): Promise<ReleaseNote[]>
   onUpdateState(cb: (s: UpdateState) => void): () => void
+
+  // ---- session snapshot (restore last layout + per-pane cwd) ----
+  getSessionState(): Promise<SessionSnapshot | null>
+  saveSessionState(snapshot: SessionSnapshot): Promise<SessionSnapshot | null>
+  /** resolve a cd-style argument against the current cwd (platform-aware) */
+  resolveCwd(current: string | undefined, arg: string): Promise<string | null>
+  /** normalize a shell-reported cwd payload (OSC 7 / OSC 9;9) */
+  reportCwd(payload: string): Promise<string | null>
 }

src/shared/ipc.ts

@@ -98,13 +98,23 @@ export const Ipc = {
   UPDATE_INSTALL: 'update:install',
   UPDATE_CHANGELOG: 'update:changelog',
   /** main -> renderer broadcast: UpdateState */
-  UPDATE_STATE: 'update:state'
+  UPDATE_STATE: 'update:state',
+
+  // ---- session snapshot (last layout + per-pane cwd) ----
+  SESSION_STATE_GET: 'session:stateGet',
+  SESSION_STATE_SET: 'session:stateSet',
+  /** resolve a cd-style argument against the current cwd, platform-aware */
+  CWD_RESOLVE: 'session:cwdResolve',
+  /** normalize a cwd reported by the shell (OSC 7 / OSC 9;9) */
+  CWD_REPORT: 'session:cwdReport'
 } as const
 
 export interface PtyCreateOptions {
   cwd?: string
   /** executable; omit for platform default shell */
   shell?: string
+  /** extra argv for the shell (shell-integration adapters use this) */
+  shellArgs?: string[]
   env?: Record<string, string>
 }
 
@@ -114,6 +124,33 @@ export interface PtyCreateResult {
   cwd: string
 }
 
+/** One dockview panel as remembered between runs. */
+export interface SessionPanelState {
+  panelId: string
+  title: string
+  kind: 'local' | 'ssh'
+  /** last known working directory (local panels; also recorded for ssh panes
+   *  so a reconnected pane starts somewhere sensible) */
+  cwd?: string
+  /** ssh only: bookmark to offer a reconnect for */
+  connectionId?: string
+  hostLabel?: string
+}
+
+/**
+ * The automatic "pick up where you left off" snapshot: the dockview layouts
+ * plus a per-panel record. Distinct from the user-managed layout templates.
+ */
+export interface SessionSnapshot {
+  version: 1
+  savedAt: number
+  mode: 'terminal' | 'ssh'
+  layouts: { terminal?: unknown; ssh?: unknown }
+  panels: SessionPanelState[]
+  /** newest cwd among local panes — seeds brand-new terminals */
+  lastLocalCwd?: string
+}
+
 export interface PtyDataEvent {
   id: string
   data: string

src/shared/settings.ts

@@ -51,6 +51,17 @@ export interface SystemSettings {
   closeAction?: 'ask' | 'tray' | 'exit'
   /** check for updates shortly after startup (manual check always available) */
   autoCheckUpdate?: boolean
+  /**
+   * Restore the previous layout and each pane's working directory on launch
+   * (see the session snapshot). On by default — that is the point of it.
+   */
+  restoreSession?: boolean
+  /**
+   * Let the shell announce its cwd over OSC 7 (shell integration). Exact, but
+   * it wraps the user's prompt, so it is opt-in; without it the app falls back
+   * to parsing typed `cd` commands.
+   */
+  shellIntegration?: boolean
 }
 
 export interface AppSettings {
@@ -107,5 +118,5 @@ export const DEFAULT_SETTINGS: AppSettings = {
   },
   customThemes: [],
   highlightRules: DEFAULT_HIGHLIGHT_RULES,
-  system: { launchAtLogin: false, preventSleep: false, globalShowHide: '', closeAction: 'tray', autoCheckUpdate: true }
+  system: { launchAtLogin: false, preventSleep: false, globalShowHide: '', closeAction: 'tray', autoCheckUpdate: true, restoreSession: true, shellIntegration: false }
 }