fix: close alignment review races and preserve local conversation state

scripts/session-composer-alignment-regression.tsx

@@ -141,7 +141,7 @@ async function main() {
   // Automatic invalid-model repair is unrelated to a failed permission choice.
   useChatStore.setState(state => ({ sessions: state.sessions.map(item => item.id === 'a' ? { ...item, modelId:'deleted' } : item) }))
   await assert.rejects(useChatStore.getState().send('automatic model fallback must not clear permission failure'), /cannot save downgrade/)
-  assert.equal(useChatStore.getState().sessions.find(item => item.id === 'a')?.modelId, model.id)
+  assert.equal(useChatStore.getState().sessions.find(item => item.id === 'a')?.modelId, 'deleted', 'failed settings block automatic repair as well as submission')
   await useChatStore.getState().selectAgentMode('plan')
   await assert.rejects(useChatStore.getState().send('mode save must not clear permission failure'), /cannot save downgrade/)
   await useChatStore.getState().selectAgentMode('craft')
@@ -184,6 +184,35 @@ async function main() {
   assert.equal(useChatStore.getState().currentSessionId, null)
   assert.equal(useChatStore.getState().draftContext.permissionMode, 'default-sandbox', 'pending creation cannot overwrite newer draft preference')
 
+  for (const initialModel of [undefined, 'deleted']) {
+    for (const queued of [false, true]) {
+      setup()
+      const owner = `pending-model-${initialModel}-${queued}`
+      const chosen = { ...model, id: 'chosen', name: 'Chosen' }
+      useSettingsStore.setState({ models: [model, chosen], selectedModelId: model.id })
+      useChatStore.setState({ currentSessionId: owner, sessions: [{ ...session(owner), modelId: initialModel }],
+        ...(queued ? { runs: { existing: { runId: 'existing', assistantId: 'assistant', sessionId: owner } } } : {}) })
+      const choice = deferred<SessionMeta>()
+      const writes: Array<{ id: string; modelId?: string }> = []
+      window.ycode.session.updateContext = async (id, patch) => {
+        writes.push({ id, modelId: patch.modelId })
+        if (writes.length === 1) return choice.promise
+        return { ...session(id), ...patch }
+      }
+      if (queued) window.ycode.chat.queue = { enqueue: async (payload: SendPayload) => { sent = payload; return {} } } as any
+      const choosing = useChatStore.getState().selectModel(chosen.id)
+      const nextSend = useChatStore.getState().send('explicit pending choice wins')
+      assert.equal(sent, undefined)
+      // Switching views while the save is pending must not repair the new owner.
+      useChatStore.setState({ currentSessionId: 'b' })
+      choice.resolve({ ...session(owner), modelId: chosen.id })
+      await choosing; await nextSend
+      assert.deepEqual(writes, [{ id: owner, modelId: chosen.id }], 'fallback cannot overwrite a pending explicit choice')
+      assert.equal(sent?.sessionId, owner)
+      assert.equal(useChatStore.getState().sessions.find(item => item.id === owner)?.modelId, chosen.id)
+    }
+  }
+
   assert.equal(renderToStaticMarkup(<ModeChip mode="craft" onClear={() => {}} />), '')
   assert.match(renderToStaticMarkup(<ModeChip mode="plan" onClear={() => {}} />), /退出计划模式/)
   assert.doesNotMatch(renderToStaticMarkup(<ModeChip mode="ask" disabled onClear={() => {}} />), /<button/)