simstudioai · icecrasher321 · Feb 10, 2026 · Feb 10, 2026 · Feb 10, 2026 · Feb 10, 2026
diff --git a/apps/sim/app/api/a2a/agents/[agentId]/route.ts b/apps/sim/app/api/a2a/agents/[agentId]/route.ts
@@ -41,7 +41,12 @@ export async function GET(request: NextRequest, { params }: { params: Promise<Ro
 
     if (!agent.agent.isPublished) {
       const auth = await checkSessionOrInternalAuth(request, { requireWorkflowId: false })
-      if (!auth.success) {
+      if (!auth.success || !auth.userId) {
+        return NextResponse.json({ error: 'Agent not published' }, { status: 404 })
+      }
+
+      const workspaceAccess = await checkWorkspaceAccess(agent.agent.workspaceId, auth.userId)
+      if (!workspaceAccess.exists || !workspaceAccess.hasAccess) {
         return NextResponse.json({ error: 'Agent not published' }, { status: 404 })
       }
     }

diff --git a/apps/sim/app/api/a2a/agents/route.ts b/apps/sim/app/api/a2a/agents/route.ts
@@ -16,7 +16,7 @@ import { sanitizeAgentName } from '@/lib/a2a/utils'
 import { checkSessionOrInternalAuth } from '@/lib/auth/hybrid'
 import { loadWorkflowFromNormalizedTables } from '@/lib/workflows/persistence/utils'
 import { hasValidStartBlockInState } from '@/lib/workflows/triggers/trigger-utils'
-import { getWorkspaceById } from '@/lib/workspaces/permissions/utils'
+import { checkWorkspaceAccess } from '@/lib/workspaces/permissions/utils'
 
 const logger = createLogger('A2AAgentsAPI')
 
@@ -39,10 +39,13 @@ export async function GET(request: NextRequest) {
       return NextResponse.json({ error: 'workspaceId is required' }, { status: 400 })
     }
 
-    const ws = await getWorkspaceById(workspaceId)
-    if (!ws) {
+    const workspaceAccess = await checkWorkspaceAccess(workspaceId, auth.userId)
+    if (!workspaceAccess.exists) {
       return NextResponse.json({ error: 'Workspace not found' }, { status: 404 })
     }
+    if (!workspaceAccess.hasAccess) {
+      return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
+    }
 
     const agents = await db
       .select({
@@ -103,6 +106,14 @@ export async function POST(request: NextRequest) {
       )
     }
 
+    const workspaceAccess = await checkWorkspaceAccess(workspaceId, auth.userId)
+    if (!workspaceAccess.exists) {
+      return NextResponse.json({ error: 'Workspace not found' }, { status: 404 })
+    }
+    if (!workspaceAccess.canWrite) {
+      return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
+    }
+
     const [wf] = await db
       .select({
         id: workflow.id,

diff --git a/apps/sim/app/api/a2a/serve/[agentId]/route.ts b/apps/sim/app/api/a2a/serve/[agentId]/route.ts
@@ -19,6 +19,8 @@ import { validateUrlWithDNS } from '@/lib/core/security/input-validation.server'
 import { SSE_HEADERS } from '@/lib/core/utils/sse'
 import { getBaseUrl } from '@/lib/core/utils/urls'
 import { markExecutionCancelled } from '@/lib/execution/cancellation'
+import { checkWorkspaceAccess } from '@/lib/workspaces/permissions/utils'
+import { getWorkspaceBilledAccountUserId } from '@/lib/workspaces/utils'
 import {
   A2A_ERROR_CODES,
   A2A_METHODS,
@@ -191,6 +193,9 @@ export async function POST(request: NextRequest, { params }: { params: Promise<R
 
     const authSchemes = (agent.authentication as { schemes?: string[] })?.schemes || []
     const requiresAuth = !authSchemes.includes('none')
+    let authenticatedUserId: string | null = null
+    let authenticatedAuthType: 'session' | 'api_key' | 'internal_jwt' | undefined
+    let authenticatedApiKeyType: 'personal' | 'workspace' | undefined
 
     if (requiresAuth) {
       const auth = await checkHybridAuth(request, { requireWorkflowId: false })
@@ -200,6 +205,17 @@ export async function POST(request: NextRequest, { params }: { params: Promise<R
           { status: 401 }
         )
       }
+      authenticatedUserId = auth.userId
+      authenticatedAuthType = auth.authType
+      authenticatedApiKeyType = auth.apiKeyType
+
+      const workspaceAccess = await checkWorkspaceAccess(agent.workspaceId, authenticatedUserId)
+      if (!workspaceAccess.exists || !workspaceAccess.hasAccess) {
+        return NextResponse.json(
+          createError(null, A2A_ERROR_CODES.AUTHENTICATION_REQUIRED, 'Access denied'),
+          { status: 403 }
+        )
+      }
     }
 
     const [wf] = await db
@@ -225,34 +241,61 @@ export async function POST(request: NextRequest, { params }: { params: Promise<R
     }
 
     const { id, method, params: rpcParams } = body
-    const apiKey = request.headers.get('X-API-Key')
+    const requestApiKey = request.headers.get('X-API-Key')
+    const apiKey = authenticatedAuthType === 'api_key' ? requestApiKey : null
+    const isPersonalApiKeyCaller =
+      authenticatedAuthType === 'api_key' && authenticatedApiKeyType === 'personal'
+    const billedUserId = await getWorkspaceBilledAccountUserId(agent.workspaceId)
+    if (!billedUserId) {
+      logger.error('Unable to resolve workspace billed account for A2A execution', {
+        agentId: agent.id,
+        workspaceId: agent.workspaceId,
+      })
+      return NextResponse.json(
+        createError(
+          id,
+          A2A_ERROR_CODES.INTERNAL_ERROR,
+          'Unable to resolve billing account for this workspace'
+        ),
+        { status: 500 }
+      )
+    }
+    const executionUserId =
+      isPersonalApiKeyCaller && authenticatedUserId ? authenticatedUserId : billedUserId
 
     logger.info(`A2A request: ${method} for agent ${agentId}`)
 
     switch (method) {
       case A2A_METHODS.MESSAGE_SEND:
-        return handleMessageSend(id, agent, rpcParams as MessageSendParams, apiKey)
+        return handleMessageSend(id, agent, rpcParams as MessageSendParams, apiKey, executionUserId)
 
       case A2A_METHODS.MESSAGE_STREAM:
-        return handleMessageStream(request, id, agent, rpcParams as MessageSendParams, apiKey)
+        return handleMessageStream(
+          request,
+          id,
+          agent,
+          rpcParams as MessageSendParams,
+          apiKey,
+          executionUserId
+        )
 
       case A2A_METHODS.TASKS_GET:
-        return handleTaskGet(id, rpcParams as TaskIdParams)
+        return handleTaskGet(id, agent.id, rpcParams as TaskIdParams)
 
       case A2A_METHODS.TASKS_CANCEL:
-        return handleTaskCancel(id, rpcParams as TaskIdParams)
+        return handleTaskCancel(id, agent.id, rpcParams as TaskIdParams)
 
       case A2A_METHODS.TASKS_RESUBSCRIBE:
-        return handleTaskResubscribe(request, id, rpcParams as TaskIdParams)
+        return handleTaskResubscribe(request, id, agent.id, rpcParams as TaskIdParams)
 
       case A2A_METHODS.PUSH_NOTIFICATION_SET:
-        return handlePushNotificationSet(id, rpcParams as PushNotificationSetParams)
+        return handlePushNotificationSet(id, agent.id, rpcParams as PushNotificationSetParams)
 
       case A2A_METHODS.PUSH_NOTIFICATION_GET:
-        return handlePushNotificationGet(id, rpcParams as TaskIdParams)
+        return handlePushNotificationGet(id, agent.id, rpcParams as TaskIdParams)
 
       case A2A_METHODS.PUSH_NOTIFICATION_DELETE:
-        return handlePushNotificationDelete(id, rpcParams as TaskIdParams)
+        return handlePushNotificationDelete(id, agent.id, rpcParams as TaskIdParams)
 
       default:
         return NextResponse.json(
@@ -268,6 +311,14 @@ export async function POST(request: NextRequest, { params }: { params: Promise<R
   }
 }
 
+async function getTaskForAgent(taskId: string, agentId: string) {
+  const [task] = await db.select().from(a2aTask).where(eq(a2aTask.id, taskId)).limit(1)
+  if (!task || task.agentId !== agentId) {
+    return null
+  }
+  return task
+}
+
 /**
  * Handle message/send - Send a message (v0.3)
  */
@@ -280,7 +331,8 @@ async function handleMessageSend(
     workspaceId: string
   },
   params: MessageSendParams,
-  apiKey?: string | null
+  apiKey?: string | null,
+  executionUserId?: string
 ): Promise<NextResponse> {
   if (!params?.message) {
     return NextResponse.json(
@@ -318,6 +370,13 @@ async function handleMessageSend(
         )
       }
 
+      if (existingTask.agentId !== agent.id) {
+        return NextResponse.json(
+          createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'),
+          { status: 404 }
+        )
+      }
+
       if (isTerminalState(existingTask.status as TaskState)) {
         return NextResponse.json(
           createError(id, A2A_ERROR_CODES.TASK_ALREADY_COMPLETE, 'Task already in terminal state'),
@@ -363,6 +422,7 @@ async function handleMessageSend(
     } = await buildExecuteRequest({
       workflowId: agent.workflowId,
       apiKey,
+      userId: executionUserId,
     })
 
     logger.info(`Executing workflow ${agent.workflowId} for A2A task ${taskId}`)
@@ -475,7 +535,8 @@ async function handleMessageStream(
     workspaceId: string
   },
   params: MessageSendParams,
-  apiKey?: string | null
+  apiKey?: string | null,
+  executionUserId?: string
 ): Promise<NextResponse> {
   if (!params?.message) {
     return NextResponse.json(
@@ -522,6 +583,13 @@ async function handleMessageStream(
       })
     }
 
+    if (existingTask.agentId !== agent.id) {
+      await releaseLock(lockKey, lockValue)
+      return NextResponse.json(createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'), {
+        status: 404,
+      })
+    }
+
     if (isTerminalState(existingTask.status as TaskState)) {
       await releaseLock(lockKey, lockValue)
       return NextResponse.json(
@@ -595,6 +663,7 @@ async function handleMessageStream(
         } = await buildExecuteRequest({
           workflowId: agent.workflowId,
           apiKey,
+          userId: executionUserId,
           stream: true,
         })
 
@@ -788,7 +857,11 @@ async function handleMessageStream(
 /**
  * Handle tasks/get - Query task status
  */
-async function handleTaskGet(id: string | number, params: TaskIdParams): Promise<NextResponse> {
+async function handleTaskGet(
+  id: string | number,
+  agentId: string,
+  params: TaskIdParams
+): Promise<NextResponse> {
   if (!params?.id) {
     return NextResponse.json(
       createError(id, A2A_ERROR_CODES.INVALID_PARAMS, 'Task ID is required'),
@@ -801,7 +874,7 @@ async function handleTaskGet(id: string | number, params: TaskIdParams): Promise
       ? params.historyLength
       : undefined
 
-  const [task] = await db.select().from(a2aTask).where(eq(a2aTask.id, params.id)).limit(1)
+  const task = await getTaskForAgent(params.id, agentId)
 
   if (!task) {
     return NextResponse.json(createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'), {
@@ -825,15 +898,19 @@ async function handleTaskGet(id: string | number, params: TaskIdParams): Promise
 /**
  * Handle tasks/cancel - Cancel a running task
  */
-async function handleTaskCancel(id: string | number, params: TaskIdParams): Promise<NextResponse> {
+async function handleTaskCancel(
+  id: string | number,
+  agentId: string,
+  params: TaskIdParams
+): Promise<NextResponse> {
   if (!params?.id) {
     return NextResponse.json(
       createError(id, A2A_ERROR_CODES.INVALID_PARAMS, 'Task ID is required'),
       { status: 400 }
     )
   }
 
-  const [task] = await db.select().from(a2aTask).where(eq(a2aTask.id, params.id)).limit(1)
+  const task = await getTaskForAgent(params.id, agentId)
 
   if (!task) {
     return NextResponse.json(createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'), {
@@ -897,6 +974,7 @@ async function handleTaskCancel(id: string | number, params: TaskIdParams): Prom
 async function handleTaskResubscribe(
   request: NextRequest,
   id: string | number,
+  agentId: string,
   params: TaskIdParams
 ): Promise<NextResponse> {
   if (!params?.id) {
@@ -906,7 +984,7 @@ async function handleTaskResubscribe(
     )
   }
 
-  const [task] = await db.select().from(a2aTask).where(eq(a2aTask.id, params.id)).limit(1)
+  const task = await getTaskForAgent(params.id, agentId)
 
   if (!task) {
     return NextResponse.json(createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'), {
@@ -1103,6 +1181,7 @@ async function handleTaskResubscribe(
  */
 async function handlePushNotificationSet(
   id: string | number,
+  agentId: string,
   params: PushNotificationSetParams
 ): Promise<NextResponse> {
   if (!params?.id) {
@@ -1130,7 +1209,7 @@ async function handlePushNotificationSet(
     )
   }
 
-  const [task] = await db.select().from(a2aTask).where(eq(a2aTask.id, params.id)).limit(1)
+  const task = await getTaskForAgent(params.id, agentId)
 
   if (!task) {
     return NextResponse.json(createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'), {
@@ -1181,6 +1260,7 @@ async function handlePushNotificationSet(
  */
 async function handlePushNotificationGet(
   id: string | number,
+  agentId: string,
   params: TaskIdParams
 ): Promise<NextResponse> {
   if (!params?.id) {
@@ -1190,7 +1270,7 @@ async function handlePushNotificationGet(
     )
   }
 
-  const [task] = await db.select().from(a2aTask).where(eq(a2aTask.id, params.id)).limit(1)
+  const task = await getTaskForAgent(params.id, agentId)
 
   if (!task) {
     return NextResponse.json(createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'), {
@@ -1224,6 +1304,7 @@ async function handlePushNotificationGet(
  */
 async function handlePushNotificationDelete(
   id: string | number,
+  agentId: string,
   params: TaskIdParams
 ): Promise<NextResponse> {
   if (!params?.id) {
@@ -1233,7 +1314,7 @@ async function handlePushNotificationDelete(
     )
   }
 
-  const [task] = await db.select().from(a2aTask).where(eq(a2aTask.id, params.id)).limit(1)
+  const task = await getTaskForAgent(params.id, agentId)
 
   if (!task) {
     return NextResponse.json(createError(id, A2A_ERROR_CODES.TASK_NOT_FOUND, 'Task not found'), {

diff --git a/apps/sim/app/api/a2a/serve/[agentId]/utils.ts b/apps/sim/app/api/a2a/serve/[agentId]/utils.ts
@@ -105,6 +105,7 @@ export function formatTaskResponse(task: Task, historyLength?: number): Task {
 export interface ExecuteRequestConfig {
   workflowId: string
   apiKey?: string | null
+  userId?: string
   stream?: boolean
 }
 
@@ -124,7 +125,7 @@ export async function buildExecuteRequest(
   if (config.apiKey) {
     headers['X-API-Key'] = config.apiKey
   } else {
-    const internalToken = await generateInternalToken()
+    const internalToken = await generateInternalToken(config.userId)
     headers.Authorization = `Bearer ${internalToken}`
     useInternalAuth = true
   }