重构: aichat 双轨状态机收口 + AiCompressed 事件拆分

- generating bool + CONV_STATE_ENABLED 开关双轨退役,ConvState enum 单一真相源
- can_accept_request 接入 chat 域入口(覆盖 Stopping 竞态,严谨于 is_active)
- AiCompressed 拆 AiManualCompressed/AiAutoCompressed(治自动压缩误触桌面toast+刷新)
- convStates/getConvState 下沉 aiShared.ts 破循环依赖

src/composables/ai/useAiConversations.ts

@@ -10,7 +10,7 @@ import { state } from '@/stores/ai'
 import { notifyConversationChanged } from './useAiEvents'
 import { persistUiState } from './useAiPanel'
 import { setStreaming } from './streamingGuard'
-import { nextMsgId } from './aiShared'
+import { nextMsgId, getConvState } from './aiShared'
 import { t } from '@/i18n/i18n-helpers'
 import type { AiMessage, AiToolCallInfo } from '@/api/types'
 
@@ -101,8 +101,11 @@ export async function switchConversation(id: string) {
   // 否则残留 stop 按钮(ChatInput.vue:88 v-if=streaming)→ 点击 store.stopChat 传 activeConversationId
   // 发错会话。对齐 newConversation 复位语义;目标在后台生成时保留 true(stop/流式显示正确)。
   // 根治归 F-09 B 路线:streaming 改 per-conv 态。此处为 A 路线过渡补丁。
-  // 走 setStreaming guard 收敛写入口(convId=id 联动幂等——has(id) 决定值,add/delete 幂等无副作用)。
-  setStreaming(state.generatingConvs.has(id), { convId: id, reason: 'switchConversation-recompute' })
+  // 批4 双轨收口:读 getConvState(enum 真相源)派生,替代旧 generatingConvs.has。
+  // 桥接语义:has(id)=true 等价于 conv_state∈{generating,stopping,compressed}(非终止三态)。
+  const targetCs = getConvState(id)
+  const targetGen = targetCs === 'generating' || targetCs === 'stopping' || targetCs === 'compressed'
+  setStreaming(targetGen, { convId: id, reason: 'switchConversation-recompute' })
 
   try {
     const rawMsgs = typeof detail.messages === 'string'