Improve message stream caching and virtualization for large sessions

packages/ui/src/stores/instances.ts

@@ -20,7 +20,7 @@ import { preferences } from "./preferences"
 import { setSessionPendingPermission } from "./session-state"
 import { setHasInstances } from "./ui"
 import { messageStoreBus } from "./message-v2/bus"
-import { clearScrollCacheForInstance } from "../lib/scroll-cache"
+import { clearCacheForInstance } from "../lib/global-cache"
 import type { MessageRecord } from "./message-v2/types"
 
 
@@ -296,7 +296,7 @@ function removeInstance(id: string) {
   }
 
   // Clean up session indexes and drafts for removed instance
-  clearScrollCacheForInstance(id)
+  clearCacheForInstance(id)
   messageStoreBus.unregisterInstance(id)
   clearInstanceDraftPrompts(id)
 }

packages/ui/src/stores/message-v2/bus.ts

@@ -1,8 +1,10 @@
 import { createInstanceMessageStore } from "./instance-store"
 import type { InstanceMessageStore } from "./instance-store"
+import { clearCacheForInstance } from "../../lib/global-cache"
 
 class MessageStoreBus {
   private stores = new Map<string, InstanceMessageStore>()
+  private teardownHandlers = new Set<(instanceId: string) => void>()
 
   registerInstance(instanceId: string, store?: InstanceMessageStore): InstanceMessageStore {
     if (this.stores.has(instanceId)) {
@@ -22,20 +24,41 @@ class MessageStoreBus {
     return this.registerInstance(instanceId)
   }
 
+  onInstanceDestroyed(handler: (instanceId: string) => void): () => void {
+    this.teardownHandlers.add(handler)
+    return () => {
+      this.teardownHandlers.delete(handler)
+    }
+  }
+
   unregisterInstance(instanceId: string) {
     const store = this.stores.get(instanceId)
     if (store) {
       store.clearInstance()
     }
+    clearCacheForInstance(instanceId)
+    this.notifyInstanceDestroyed(instanceId)
     this.stores.delete(instanceId)
   }
 
   clearAll() {
     for (const [instanceId, store] of this.stores.entries()) {
       store.clearInstance()
+      clearCacheForInstance(instanceId)
+      this.notifyInstanceDestroyed(instanceId)
       this.stores.delete(instanceId)
     }
   }
+
+  private notifyInstanceDestroyed(instanceId: string) {
+    for (const handler of this.teardownHandlers) {
+      try {
+        handler(instanceId)
+      } catch (error) {
+        console.error("Failed to run message store teardown handler", error)
+      }
+    }
+  }
 }
 
 export const messageStoreBus = new MessageStoreBus()

packages/ui/src/stores/message-v2/instance-store.ts

@@ -24,6 +24,7 @@ function createInitialState(instanceId: string): InstanceMessageState {
     messages: {},
     messageInfoVersion: {},
     pendingParts: {},
+    sessionRevisions: {},
     permissions: {
       queue: [],
       active: null,
@@ -41,8 +42,52 @@ function ensurePartId(messageId: string, part: ClientPart, index: number): strin
   return `${messageId}-part-${index}`
 }
 
+const PENDING_PART_MAX_AGE_MS = 30_000
+
 function clonePart(part: ClientPart): ClientPart {
-  return JSON.parse(JSON.stringify(part)) as ClientPart
+  if (!part || typeof part !== "object") {
+    return part
+  }
+  const cloned: Record<string, any> = { ...part }
+  if ("renderCache" in cloned) {
+    cloned.renderCache = undefined
+  }
+  if ("text" in cloned) {
+    cloned.text = cloneStructuredValue(cloned.text)
+  }
+  if ("thinking" in cloned && typeof cloned.thinking === "object") {
+    cloned.thinking = cloneStructuredValue(cloned.thinking)
+  }
+  if ("content" in cloned && Array.isArray(cloned.content)) {
+    cloned.content = cloneStructuredValue(cloned.content)
+  }
+  return cloned as ClientPart
+}
+
+function cloneStructuredValue<T>(value: T): T {
+  if (Array.isArray(value)) {
+    return value.map((item) => cloneStructuredValue(item)) as T
+  }
+  if (value && typeof value === "object") {
+    const next: Record<string, any> = {}
+    Object.entries(value as Record<string, any>).forEach(([key, nested]) => {
+      next[key] = cloneStructuredValue(nested)
+    })
+    return next as T
+  }
+  return value
+}
+
+function areMessageIdListsEqual(a: string[], b: string[]): boolean {
+  if (a.length !== b.length) {
+    return false
+  }
+  for (let index = 0; index < a.length; index++) {
+    if (a[index] !== b[index]) {
+      return false
+    }
+  }
+  return true
 }
 
 function createEmptyUsageState(): SessionUsageState {
@@ -158,6 +203,7 @@ export interface InstanceMessageStore {
   getSessionUsage: (sessionId: string) => SessionUsageState | undefined
   setScrollSnapshot: (sessionId: string, scope: string, snapshot: Omit<ScrollSnapshot, "updatedAt">) => void
   getScrollSnapshot: (sessionId: string, scope: string) => ScrollSnapshot | undefined
+  getSessionRevision: (sessionId: string) => number
   getSessionMessageIds: (sessionId: string) => string[]
   getMessage: (messageId: string) => MessageRecord | undefined
   clearInstance: () => void
@@ -167,6 +213,15 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
   const [state, setState] = createStore<InstanceMessageState>(createInitialState(instanceId))
   const messageInfoCache = new Map<string, MessageInfo>()
 
+  function bumpSessionRevision(sessionId: string) {
+    if (!sessionId) return
+    setState("sessionRevisions", sessionId, (value = 0) => value + 1)
+  }
+
+  function getSessionRevisionValue(sessionId: string) {
+    return state.sessionRevisions[sessionId] ?? 0
+  }
+
   function withUsageState(sessionId: string, updater: (draft: SessionUsageState) => void) {
     setState("usage", sessionId, (current) => {
       const draft = current
@@ -223,6 +278,7 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
 
   function addOrUpdateSession(input: SessionUpsertInput) {
     const session = ensureSessionEntry(input.id)
+    const previousIds = [...session.messageIds]
     const nextMessageIds = Array.isArray(input.messageIds) ? input.messageIds : session.messageIds
 
     setState("sessions", input.id, {
@@ -233,6 +289,10 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
       messageIds: nextMessageIds,
       revert: input.revert ?? session.revert ?? null,
     })
+
+    if (Array.isArray(input.messageIds) && !areMessageIdListsEqual(previousIds, nextMessageIds)) {
+      bumpSessionRevision(input.id)
+    }
   }
 
   function hydrateMessages(sessionId: string, inputs: MessageUpsertInput[], infos?: Iterable<MessageInfo>) {
@@ -303,7 +363,7 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
 
     setState("messages", (prev) => ({ ...prev, ...nextMessages }))
     setState("messageInfoVersion", (prev) => ({ ...prev, ...nextMessageInfoVersion }))
-    setState("pendingParts", (prev) => ({ ...prev, ...nextPendingParts }))
+    setState("pendingParts", () => nextPendingParts)
     setState("permissions", "byMessage", (prev) => ({ ...prev, ...nextPermissionsByMessage }))
 
     if (usageState) {
@@ -315,6 +375,8 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
       messageIds: incomingIds,
       updatedAt: Date.now(),
     }))
+
+    bumpSessionRevision(sessionId)
   }
 
   function insertMessageIntoSession(sessionId: string, messageId: string) {
@@ -374,12 +436,24 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
 
     insertMessageIntoSession(input.sessionId, input.id)
     flushPendingParts(input.id)
+    bumpSessionRevision(input.sessionId)
   }
 
   function bufferPendingPart(entry: PendingPartEntry) {
     setState("pendingParts", entry.messageId, (list = []) => [...list, entry])
   }
 
+  function clearPendingPartsForMessage(messageId: string) {
+    setState("pendingParts", (prev) => {
+      if (!prev[messageId]) {
+        return prev
+      }
+      const next = { ...prev }
+      delete next[messageId]
+      return next
+    })
+  }
+
   function applyPartUpdate(input: PartUpdateInput) {
     const message = state.messages[input.messageId]
     if (!message) {
@@ -417,12 +491,14 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
     if (!pending || pending.length === 0) {
       return
     }
-    pending.forEach((entry) => applyPartUpdate({ messageId, part: entry.part }))
-    setState("pendingParts", (prev) => {
-      const next = { ...prev }
-      delete next[messageId]
-      return next
-    })
+    const now = Date.now()
+    const validEntries = pending.filter((entry) => now - entry.receivedAt <= PENDING_PART_MAX_AGE_MS)
+    if (validEntries.length === 0) {
+      clearPendingPartsForMessage(messageId)
+      return
+    }
+    validEntries.forEach((entry) => applyPartUpdate({ messageId, part: entry.part }))
+    clearPendingPartsForMessage(messageId)
   }
 
   function replaceMessageId(options: ReplaceMessageIdOptions) {
@@ -444,6 +520,8 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
       return next
     })
 
+    const affectedSessions = new Set<string>()
+
     Object.values(state.sessions).forEach((session) => {
       const index = session.messageIds.indexOf(options.oldId)
       if (index === -1) return
@@ -452,8 +530,11 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
         next[index] = options.newId
         return next
       })
+      affectedSessions.add(session.id)
     })
 
+    affectedSessions.forEach((sessionId) => bumpSessionRevision(sessionId))
+
     const infoEntry = messageInfoCache.get(options.oldId)
     if (infoEntry) {
       messageInfoCache.set(options.newId, infoEntry)
@@ -482,12 +563,8 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
     const pending = state.pendingParts[options.oldId]
     if (pending) {
       setState("pendingParts", options.newId, pending)
-      setState("pendingParts", (prev) => {
-        const next = { ...prev }
-        delete next[options.oldId]
-        return next
-      })
     }
+    clearPendingPartsForMessage(options.oldId)
   }
 
   function setMessageInfo(messageId: string, info: MessageInfo) {
@@ -608,6 +685,7 @@ export function createInstanceMessageStore(instanceId: string): InstanceMessageS
     getSessionUsage,
     setScrollSnapshot,
     getScrollSnapshot,
+    getSessionRevision: getSessionRevisionValue,
     getSessionMessageIds: (sessionId: string) => state.sessions[sessionId]?.messageIds ?? [],
     getMessage: (messageId: string) => state.messages[messageId],
     clearInstance,

packages/ui/src/stores/message-v2/normalizers.ts

@@ -1,6 +1,4 @@
 import { decodeHtmlEntities } from "../../lib/markdown"
-import { partHasRenderableText } from "../../types/message"
-import type { MessageDisplayParts, Message } from "../../types/message"
 
 function decodeTextSegment(segment: any): any {
   if (typeof segment === "string") {
@@ -74,23 +72,3 @@ export function normalizeMessagePart(part: any): any {
   return normalized
 }
 
-export function computeDisplayParts(message: Message, showThinking: boolean): MessageDisplayParts {
-  const text: any[] = []
-  const tool: any[] = []
-  const reasoning: any[] = []
-
-  for (const part of message.parts) {
-    if (part.type === "text" && !part.synthetic && partHasRenderableText(part)) {
-      text.push(part)
-    } else if (part.type === "tool") {
-      tool.push(part)
-    } else if (part.type === "reasoning" && showThinking && partHasRenderableText(part)) {
-      reasoning.push(part)
-    }
-  }
-
-  const combined = reasoning.length > 0 ? [...text, ...reasoning] : [...text]
-  const version = typeof message.version === "number" ? message.version : 0
-
-  return { text, tool, reasoning, combined, showThinking, version }
-}

packages/ui/src/stores/message-v2/record-display-cache.ts

@@ -0,0 +1,72 @@
+import type { ClientPart } from "../../types/message"
+import { partHasRenderableText } from "../../types/message"
+import type { MessageRecord } from "./types"
+
+export type ToolCallPart = Extract<ClientPart, { type: "tool" }>
+
+export interface RecordDisplayData {
+  orderedParts: ClientPart[]
+  textAndReasoningParts: ClientPart[]
+  toolParts: ToolCallPart[]
+}
+
+interface RecordDisplayCacheEntry {
+  revision: number
+  data: RecordDisplayData
+}
+
+const recordDisplayCache = new Map<string, RecordDisplayCacheEntry>()
+
+function makeCacheKey(instanceId: string, messageId: string, showThinking: boolean) {
+  return `${instanceId}:${messageId}:${showThinking ? 1 : 0}`
+}
+
+function isToolPart(part: ClientPart): part is ToolCallPart {
+  return part.type === "tool"
+}
+
+export function buildRecordDisplayData(instanceId: string, record: MessageRecord, showThinking: boolean): RecordDisplayData {
+  const cacheKey = makeCacheKey(instanceId, record.id, showThinking)
+  const cached = recordDisplayCache.get(cacheKey)
+  if (cached && cached.revision === record.revision) {
+    return cached.data
+  }
+
+  const orderedParts: ClientPart[] = []
+  const textAndReasoningParts: ClientPart[] = []
+  const toolParts: ToolCallPart[] = []
+
+  for (const partId of record.partIds) {
+    const entry = record.parts[partId]
+    if (!entry?.data) continue
+    const part = entry.data
+    orderedParts.push(part)
+
+    if (isToolPart(part)) {
+      toolParts.push(part)
+      continue
+    }
+
+    if (part.type === "text" && !part.synthetic && partHasRenderableText(part)) {
+      textAndReasoningParts.push(part)
+      continue
+    }
+
+    if (part.type === "reasoning" && showThinking && partHasRenderableText(part)) {
+      textAndReasoningParts.push(part)
+    }
+  }
+
+  const data = { orderedParts, textAndReasoningParts, toolParts }
+  recordDisplayCache.set(cacheKey, { revision: record.revision, data })
+  return data
+}
+
+export function clearRecordDisplayCacheForInstance(instanceId: string) {
+  const prefix = `${instanceId}:`
+  for (const key of recordDisplayCache.keys()) {
+    if (key.startsWith(prefix)) {
+      recordDisplayCache.delete(key)
+    }
+  }
+}

packages/ui/src/stores/message-v2/types.ts

@@ -95,8 +95,7 @@ export interface InstanceMessageState {
   messages: Record<string, MessageRecord>
   messageInfoVersion: Record<string, number>
   pendingParts: Record<string, PendingPartEntry[]>
-
-
+  sessionRevisions: Record<string, number>
   permissions: InstancePermissionState
   usage: Record<string, SessionUsageState>
   scrollState: Record<string, ScrollSnapshot>