feat: persist context snapshots and defer permission changes to next messages

scripts/context-usage-regression.ts

@@ -1,5 +1,6 @@
 import assert from 'node:assert/strict'
-import { createContextUsageService, type ContextUsageDependencies } from '../src/main/context-usage-service'
+import { createContextUsageService, contextSnapshotMatches, type ContextUsageDependencies } from '../src/main/context-usage-service'
+import { contextBreakdownMethodLabel } from '../src/shared/context-usage'
 import type { ChatMessage, ContextUsageBreakdown } from '../src/shared/types'
 
 const sample = {
@@ -35,12 +36,16 @@ const breakdown: ContextUsageBreakdown = {
 }
 
 function service(overrides: Partial<ContextUsageDependencies> = {}) {
+  const messages = [assistant()]
   const dependencies: ContextUsageDependencies = {
-    messages: async () => [assistant()],
+    messages: async () => messages,
     modelId: async () => 'model-a',
     running: () => false,
     summary: async () => undefined,
-    persistIfCurrent: async () => undefined,
+    persistIfCurrent: async (_id, guard, summary) => {
+      const current = await dependencies.messages(_id)
+      if(contextSnapshotMatches(current, guard, summary))current.findLast(message=>message.role==='assistant')!.contextBreakdown=summary
+    },
     ...overrides
   }
   return createContextUsageService(dependencies)
@@ -71,3 +76,37 @@ const summaryFailure = await service({ summary: async () => { throw new Error('q
 assert.equal(summaryFailure.sample?.usage.inputTokens, 1200, 'summary failures retain the real streamed usage sample')
 
 console.log('context-usage-regression: latest, previous, active-run, summary identity and failure cases passed')
+
+const cachedMessages = [assistant()]
+const originalUsage = JSON.stringify(cachedMessages[0].contextUsage)
+await service({messages:async()=>cachedMessages,summary:async()=>breakdown}).get('save')
+assert.deepEqual(cachedMessages[0].contextBreakdown,breakdown)
+assert.equal(JSON.stringify(cachedMessages[0].contextUsage),originalUsage,'saving categories never overwrites actual upstream usage')
+const coldMessages=JSON.parse(JSON.stringify(cachedMessages)) as ChatMessage[]
+for(const summary of [async()=>undefined,async()=>{throw new Error('kernel shut down')}]) {
+  const offline=await service({messages:async()=>coldMessages,summary}).get('offline')
+  assert.deepEqual(offline.breakdown,breakdown,'persisted categories survive cold/offline/no-instance queries')
+  assert.equal(offline.sample?.contextWindow,10_000)
+}
+const oldModel=await service({messages:async()=>coldMessages,modelId:async()=>'model-b'}).get('switch')
+assert.equal(oldModel.status,'previous')
+assert.equal(oldModel.sample?.contextWindow,10_000,'never combine old sample with the new selected model window')
+assert.equal((await service({summary:async()=>({...breakdown,modelId:'wrong'})}).get('wrong-model')).breakdown,undefined)
+for(const change of ['assistant','rewind','pending-user'] as const) {
+  let current=[assistant()]
+  const result=await service({messages:async()=>current,summary:async()=>{
+    if(change==='assistant')current.push(assistant({id:'new',requestId:'new-request',contextUsage:undefined}))
+    if(change==='rewind')current=[{id:'different-user',role:'user',content:'fork',createdAt:0},assistant()]
+    if(change==='pending-user')current.push({id:'pending',role:'user',content:'next',createdAt:2})
+    return breakdown
+  }}).get(change)
+  assert.equal(result.breakdown,undefined,`${change} while summary awaits cannot pollute the active branch`)
+}
+const pending=[assistant({contextBreakdown:breakdown}),{id:'pending',role:'user',content:'next',createdAt:2} as ChatMessage]
+assert.equal((await service({messages:async()=>pending,summary:async()=>breakdown}).get('pending')).status,'previous','refresh must not erase pending-user previous status')
+const categoriesOnly=await service({messages:async()=>[assistant({contextUsage:undefined,contextBreakdown:breakdown})]}).get('categories-only')
+assert.equal(categoriesOnly.status,'latest','categories without upstream usage remain available, not fake zero usage')
+assert.equal(categoriesOnly.sample,undefined)
+assert.equal(contextBreakdownMethodLabel('native-summary'),'内核 summary 本地估计')
+assert.equal(contextBreakdownMethodLabel('utf8-estimate'),'UTF-8 字节估计')
+console.log('context-usage persistence: offline, shutdown, identity races, usage preservation, category provenance passed')