fix(dev): use globalThis for singleton state to prevent HMR memory leaks (#4869)

* fix(dev): use globalThis for singleton state to prevent HMR memory leaks

* fix(dev): apply globalThis guard to rate-limiter storage factory to prevent listener accumulation

* fix(types): resolve McpConnectionManager globalThis undefined type error

Author: waleedlatif1

apps/sim/lib/copilot/persistence/tool-confirm/index.ts

@@ -9,16 +9,24 @@ import {
 import { getAsyncToolCalls } from '@/lib/copilot/async-runs/repository'
 import { MothershipStreamV1ToolOutcome } from '@/lib/copilot/generated/mothership-stream-v1'
 import { getRedisClient } from '@/lib/core/config/redis'
-import { createPubSubChannel } from '@/lib/events/pubsub'
+import { createPubSubChannel, type PubSubChannel } from '@/lib/events/pubsub'
 
 const logger = createLogger('CopilotOrchestratorPersistence')
 const TOOL_CONFIRMATION_TTL_SECONDS = 60 * 10
 const toolConfirmationKey = (toolCallId: string) => `copilot:tool-confirmation:${toolCallId}`
 
-const toolConfirmationChannel = createPubSubChannel<AsyncCompletionEnvelope>({
-  channel: 'copilot:tool-confirmation',
-  label: 'CopilotToolConfirmation',
-})
+type ToolConfirmGlobal = typeof globalThis & {
+  _toolConfirmationChannel?: PubSubChannel<AsyncCompletionEnvelope>
+}
+
+const _g = globalThis as ToolConfirmGlobal
+if (!_g._toolConfirmationChannel) {
+  _g._toolConfirmationChannel = createPubSubChannel<AsyncCompletionEnvelope>({
+    channel: 'copilot:tool-confirmation',
+    label: 'CopilotToolConfirmation',
+  })
+}
+const toolConfirmationChannel = _g._toolConfirmationChannel
 
 /**
  * Get a tool call confirmation state from the durable async tool row.

apps/sim/lib/copilot/tasks.ts

@@ -7,7 +7,7 @@
  * Channel: `task:status_changed`
  */
 
-import { createPubSubChannel } from '@/lib/events/pubsub'
+import { createPubSubChannel, type PubSubChannel } from '@/lib/events/pubsub'
 
 interface TaskStatusEvent {
   workspaceId: string
@@ -16,10 +16,20 @@ interface TaskStatusEvent {
   streamId?: string
 }
 
-const channel =
-  typeof window !== 'undefined'
-    ? null
-    : createPubSubChannel<TaskStatusEvent>({ channel: 'task:status_changed', label: 'task' })
+type TaskPubSubGlobal = typeof globalThis & {
+  _taskStatusChannel?: PubSubChannel<TaskStatusEvent> | null
+}
+
+const g = globalThis as TaskPubSubGlobal
+
+if (!('_taskStatusChannel' in g)) {
+  g._taskStatusChannel =
+    typeof window !== 'undefined'
+      ? null
+      : createPubSubChannel<TaskStatusEvent>({ channel: 'task:status_changed', label: 'task' })
+}
+
+const channel = g._taskStatusChannel
 
 export const taskPubSub = channel
   ? {

apps/sim/lib/core/config/redis.ts

@@ -54,55 +54,65 @@ export function getRedisConnectionDefaults(
   }
 }
 
-let globalRedisClient: Redis | null = null
-let pingFailures = 0
-let pingInterval: NodeJS.Timeout | null = null
-let pingInFlight = false
+interface RedisState {
+  client: Redis | null
+  pingFailures: number
+  pingInterval: NodeJS.Timeout | null
+  pingInFlight: boolean
+  reconnectListeners: Array<() => void>
+}
+
+const g = globalThis as typeof globalThis & { _redisState?: RedisState }
+if (!g._redisState) {
+  g._redisState = {
+    client: null,
+    pingFailures: 0,
+    pingInterval: null,
+    pingInFlight: false,
+    reconnectListeners: [],
+  }
+}
+const state = g._redisState
 
 const PING_INTERVAL_MS = 15_000
 const MAX_PING_FAILURES = 2
 
-/** Callbacks invoked when the PING health check forces a reconnect. */
-const reconnectListeners: Array<() => void> = []
-
 /**
  * Register a callback that fires when the PING health check forces a reconnect.
  * Useful for resetting cached adapters that hold a stale Redis reference.
  */
 export function onRedisReconnect(cb: () => void): void {
-  reconnectListeners.push(cb)
+  state.reconnectListeners.push(cb)
 }
 
 function startPingHealthCheck(redis: Redis): void {
-  if (pingInterval) return
+  if (state.pingInterval) return
 
-  pingInterval = setInterval(async () => {
-    if (pingInFlight) return
-    pingInFlight = true
+  state.pingInterval = setInterval(async () => {
+    if (state.pingInFlight) return
+    state.pingInFlight = true
     try {
       await redis.ping()
-      pingFailures = 0
+      state.pingFailures = 0
     } catch (error) {
-      pingFailures++
+      state.pingFailures++
       logger.warn('Redis PING failed', {
-        consecutiveFailures: pingFailures,
+        consecutiveFailures: state.pingFailures,
         error: toError(error).message,
       })
 
-      if (pingFailures >= MAX_PING_FAILURES) {
+      if (state.pingFailures >= MAX_PING_FAILURES) {
         logger.error('Redis PING failed consecutive times — forcing reconnect', {
-          consecutiveFailures: pingFailures,
+          consecutiveFailures: state.pingFailures,
         })
-        pingFailures = 0
-        // Drop the cached client and stop this health check before disconnecting,
-        // so the next getRedisClient() builds a fresh client and a fresh PING loop.
-        // Listeners may call getRedisClient() and must observe the cleared global.
-        globalRedisClient = null
-        if (pingInterval) {
-          clearInterval(pingInterval)
-          pingInterval = null
+        state.pingFailures = 0
+        // Clear before notifying listeners — they may call getRedisClient() and must see the reset state.
+        state.client = null
+        if (state.pingInterval) {
+          clearInterval(state.pingInterval)
+          state.pingInterval = null
         }
-        for (const cb of reconnectListeners) {
+        for (const cb of state.reconnectListeners) {
           try {
             cb()
           } catch (cbError) {
@@ -116,7 +126,7 @@ function startPingHealthCheck(redis: Redis): void {
         }
       }
     } finally {
-      pingInFlight = false
+      state.pingInFlight = false
     }
   }, PING_INTERVAL_MS)
 }
@@ -131,15 +141,15 @@ function startPingHealthCheck(redis: Redis): void {
 export function getRedisClient(): Redis | null {
   if (typeof window !== 'undefined') return null
   if (!redisUrl) return null
-  if (globalRedisClient) return globalRedisClient
+  if (state.client) return state.client
 
   // Outside the try/catch so config errors aren't silently swallowed.
   const defaults = getRedisConnectionDefaults(redisUrl)
 
   try {
     logger.info('Initializing Redis client')
 
-    globalRedisClient = new Redis(redisUrl, {
+    state.client = new Redis(redisUrl, {
       ...defaults,
       commandTimeout: 5000,
       maxRetriesPerRequest: 5,
@@ -162,17 +172,17 @@ export function getRedisClient(): Redis | null {
       },
     })
 
-    globalRedisClient.on('connect', () => logger.info('Redis connected'))
-    globalRedisClient.on('ready', () => logger.info('Redis ready'))
-    globalRedisClient.on('error', (err: Error) => {
+    state.client.on('connect', () => logger.info('Redis connected'))
+    state.client.on('ready', () => logger.info('Redis ready'))
+    state.client.on('error', (err: Error) => {
       logger.error('Redis error', { error: err.message, code: (err as any).code })
     })
-    globalRedisClient.on('close', () => logger.warn('Redis connection closed'))
-    globalRedisClient.on('end', () => logger.error('Redis connection ended'))
+    state.client.on('close', () => logger.warn('Redis connection closed'))
+    state.client.on('end', () => logger.error('Redis connection ended'))
 
-    startPingHealthCheck(globalRedisClient)
+    startPingHealthCheck(state.client)
 
-    return globalRedisClient
+    return state.client
   } catch (error) {
     logger.error('Failed to initialize Redis client', { error })
     return null
@@ -274,18 +284,18 @@ export async function extendLock(
  * Use for graceful shutdown.
  */
 export async function closeRedisConnection(): Promise<void> {
-  if (pingInterval) {
-    clearInterval(pingInterval)
-    pingInterval = null
+  if (state.pingInterval) {
+    clearInterval(state.pingInterval)
+    state.pingInterval = null
   }
 
-  if (globalRedisClient) {
+  if (state.client) {
     try {
-      await globalRedisClient.quit()
+      await state.client.quit()
     } catch (error) {
       logger.error('Error closing Redis connection', { error })
     } finally {
-      globalRedisClient = null
+      state.client = null
     }
   }
 }
@@ -294,12 +304,12 @@ export async function closeRedisConnection(): Promise<void> {
  * Reset all module-level state. Only intended for use in tests.
  */
 export function resetForTesting(): void {
-  if (pingInterval) {
-    clearInterval(pingInterval)
-    pingInterval = null
+  if (state.pingInterval) {
+    clearInterval(state.pingInterval)
+    state.pingInterval = null
   }
-  globalRedisClient = null
-  pingFailures = 0
-  pingInFlight = false
-  reconnectListeners.length = 0
+  state.client = null
+  state.pingFailures = 0
+  state.pingInFlight = false
+  state.reconnectListeners.length = 0
 }

apps/sim/lib/core/rate-limiter/storage/factory.ts

@@ -7,19 +7,27 @@ import { RedisTokenBucket } from './redis-token-bucket'
 
 const logger = createLogger('RateLimitStorage')
 
-let cachedAdapter: RateLimitStorageAdapter | null = null
-let reconnectListenerRegistered = false
+type FactoryGlobal = typeof globalThis & {
+  _rlCachedAdapter?: RateLimitStorageAdapter | null
+  _rlReconnectListenerRegistered?: boolean
+}
+
+const g = globalThis as FactoryGlobal
+if (!('_rlCachedAdapter' in g)) {
+  g._rlCachedAdapter = null
+  g._rlReconnectListenerRegistered = false
+}
 
 export function createStorageAdapter(): RateLimitStorageAdapter {
-  if (cachedAdapter) {
-    return cachedAdapter
+  if (g._rlCachedAdapter) {
+    return g._rlCachedAdapter
   }
 
-  if (!reconnectListenerRegistered) {
+  if (!g._rlReconnectListenerRegistered) {
     onRedisReconnect(() => {
-      cachedAdapter = null
+      g._rlCachedAdapter = null
     })
-    reconnectListenerRegistered = true
+    g._rlReconnectListenerRegistered = true
   }
 
   const storageMethod = getStorageMethod()
@@ -30,27 +38,27 @@ export function createStorageAdapter(): RateLimitStorageAdapter {
       logger.warn(
         'Redis configured but client unavailable - falling back to PostgreSQL for rate limiting'
       )
-      cachedAdapter = new DbTokenBucket()
+      g._rlCachedAdapter = new DbTokenBucket()
     } else {
       logger.info('Rate limiting: Using Redis')
-      cachedAdapter = new RedisTokenBucket(redis)
+      g._rlCachedAdapter = new RedisTokenBucket(redis)
     }
   } else {
     logger.info('Rate limiting: Using PostgreSQL')
-    cachedAdapter = new DbTokenBucket()
+    g._rlCachedAdapter = new DbTokenBucket()
   }
 
-  return cachedAdapter
+  return g._rlCachedAdapter!
 }
 
 export function getAdapterType(): StorageMethod {
   return getStorageMethod()
 }
 
 export function resetStorageAdapter(): void {
-  cachedAdapter = null
+  g._rlCachedAdapter = null
 }
 
 export function setStorageAdapter(adapter: RateLimitStorageAdapter): void {
-  cachedAdapter = adapter
+  g._rlCachedAdapter = adapter
 }

apps/sim/lib/execution/cancellation.ts

@@ -19,16 +19,20 @@ export type ExecutionCancellationRecordResult =
       reason: 'redis_unavailable' | 'redis_write_failed'
     }
 
-let sharedChannel: PubSubChannel<ExecutionCancelEvent> | null = null
+type CancellationGlobal = typeof globalThis & {
+  _executionCancelChannel?: PubSubChannel<ExecutionCancelEvent>
+}
+
+const _g = globalThis as CancellationGlobal
 
 export function getCancellationChannel(): PubSubChannel<ExecutionCancelEvent> {
-  if (!sharedChannel) {
-    sharedChannel = createPubSubChannel<ExecutionCancelEvent>({
+  if (!_g._executionCancelChannel) {
+    _g._executionCancelChannel = createPubSubChannel<ExecutionCancelEvent>({
       channel: EXECUTION_CANCEL_CHANNEL,
       label: 'execution-cancel',
     })
   }
-  return sharedChannel
+  return _g._executionCancelChannel
 }
 
 export function isRedisCancellationEnabled(): boolean {

apps/sim/lib/mcp/connection-manager.ts

@@ -461,6 +461,13 @@ export class McpConnectionManager {
   }
 }
 
-export const mcpConnectionManager: McpConnectionManager | null = isTest
-  ? null
-  : new McpConnectionManager()
+type McpManagerGlobal = typeof globalThis & {
+  _mcpConnectionManager?: McpConnectionManager | null
+}
+
+const _g = globalThis as McpManagerGlobal
+if (!('_mcpConnectionManager' in _g)) {
+  _g._mcpConnectionManager = isTest ? null : new McpConnectionManager()
+}
+
+export const mcpConnectionManager: McpConnectionManager | null = _g._mcpConnectionManager ?? null