feat: add TUI session orchestrator

Add a first-class active-session orchestrator for the Ink TUI:

- list, activate, close, and launch live process-local TUI sessions
- hydrate committed and in-flight output when switching sessions
- dispatch a new prompt session from the +new row with session-scoped model picks
- expose a clickable live-session count in the status chrome
- preserve stable row order while initially focusing the current session
- support mouse hit-testing for floating orchestrator overlays
- add backend and frontend regression coverage for the lifecycle and UI helpers

ui-tui/src/app/interfaces.ts

@@ -3,7 +3,7 @@ import type { MutableRefObject, ReactNode, RefObject, SetStateAction } from 'rea
 
 import type { PasteEvent } from '../components/textInput.js'
 import type { GatewayClient } from '../gatewayClient.js'
-import type { ImageAttachResponse } from '../gatewayTypes.js'
+import type { ImageAttachResponse, SessionCloseResponse } from '../gatewayTypes.js'
 import type { ParsedVoiceRecordKey } from '../lib/platform.js'
 import type { RpcResult } from '../lib/rpc.js'
 import type { Theme } from '../theme.js'
@@ -79,6 +79,7 @@ export interface OverlayState {
   pager: null | PagerState
   picker: boolean
   secret: null | SecretReq
+  sessions: boolean
   skillsHub: boolean
   sudo: null | SudoReq
 }
@@ -103,6 +104,7 @@ export interface UiState {
   detailsMode: DetailsMode
   detailsModeCommandOverride: boolean
   info: null | SessionInfo
+  liveSessionCount: number
   inlineDiffs: boolean
   mouseTracking: MouseTrackingMode
   pasteCollapseLines: number
@@ -284,6 +286,7 @@ export interface SlashHandlerContext {
     die: () => void
     dieWithCode: (code: number) => void
     guardBusySessionSwitch: (what?: string) => boolean
+    newLiveSession: (msg?: string, title?: string) => void
     newSession: (msg?: string, title?: string) => void
     resetVisibleHistory: (info?: null | SessionInfo) => void
     resumeById: (id: string) => void
@@ -311,6 +314,10 @@ export interface AppLayoutActions {
   answerSecret: (value: string) => void
   answerSudo: (pw: string) => void
   clearSelection: () => void
+  activateLiveSession: (id: string) => void
+  closeLiveSession: (id: string) => Promise<null | SessionCloseResponse>
+  newLiveSession: () => void
+  newPromptSession: (prompt: string, modelArg?: string) => void
   onModelSelect: (value: string) => void
   resumeById: (id: string) => void
   setStickyPrompt: (value: string) => void
@@ -369,7 +376,11 @@ export interface AppOverlaysProps {
   completions: CompletionItem[]
   onApprovalChoice: (choice: string) => void
   onClarifyAnswer: (value: string) => void
+  onActiveSessionSelect: (sessionId: string) => void
+  onActiveSessionClose: (sessionId: string) => Promise<null | SessionCloseResponse>
   onModelSelect: (value: string) => void
+  onNewLiveSession: () => void
+  onNewPromptSession: (prompt: string, modelArg?: string) => void
   onPickerSelect: (sessionId: string) => void
   onSecretSubmit: (value: string) => void
   onSudoSubmit: (pw: string) => void