fix(knowledge): address review comments on upsert document

- Reorder create-then-delete to prevent data loss if creation fails
- Move Zod validation before workflow authorization for validated input
- Fix btoa stack overflow for large content using loop-based encoding

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: waleedlatif1

apps/sim/app/api/knowledge/[id]/documents/upsert/route.ts

@@ -55,9 +55,11 @@ export async function POST(req: NextRequest, { params }: { params: Promise<{ id:
     }
     const userId = auth.userId
 
-    if (body.workflowId) {
+    const validatedData = UpsertDocumentSchema.parse(body)
+
+    if (validatedData.workflowId) {
       const authorization = await authorizeWorkflowByWorkspacePermission({
-        workflowId: body.workflowId,
+        workflowId: validatedData.workflowId,
         userId,
         action: 'write',
       })
@@ -82,8 +84,6 @@ export async function POST(req: NextRequest, { params }: { params: Promise<{ id:
       return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
     }
 
-    const validatedData = UpsertDocumentSchema.parse(body)
-
     let existingDocumentId: string | null = null
     let isUpdate = false
 
@@ -126,9 +126,8 @@ export async function POST(req: NextRequest, { params }: { params: Promise<{ id:
     if (existingDocumentId) {
       isUpdate = true
       logger.info(
-        `[${requestId}] Found existing document ${existingDocumentId}, deleting before re-creation`
+        `[${requestId}] Found existing document ${existingDocumentId}, creating replacement before deleting old`
       )
-      await deleteDocument(existingDocumentId, requestId)
     }
 
     const createdDocuments = await createDocumentRecords(
@@ -147,6 +146,10 @@ export async function POST(req: NextRequest, { params }: { params: Promise<{ id:
       requestId
     )
 
+    if (existingDocumentId) {
+      await deleteDocument(existingDocumentId, requestId)
+    }
+
     const firstDocument = createdDocuments[0]
 
     processDocumentsWithQueue(

apps/sim/tools/knowledge/upsert_document.ts

@@ -81,12 +81,18 @@ export const knowledgeUpsertDocumentTool: ToolConfig<
         throw new Error('Document content exceeds maximum size of 1MB')
       }
 
-      const contentBytes = new TextEncoder().encode(textContent).length
-
-      const base64Content =
-        typeof Buffer !== 'undefined'
-          ? Buffer.from(textContent, 'utf8').toString('base64')
-          : btoa(String.fromCharCode(...new TextEncoder().encode(textContent)))
+      const utf8Bytes = new TextEncoder().encode(textContent)
+      const contentBytes = utf8Bytes.length
+      let base64Content: string
+      if (typeof Buffer !== 'undefined') {
+        base64Content = Buffer.from(textContent, 'utf8').toString('base64')
+      } else {
+        let binary = ''
+        for (let i = 0; i < utf8Bytes.length; i++) {
+          binary += String.fromCharCode(utf8Bytes[i])
+        }
+        base64Content = btoa(binary)
+      }
 
       const dataUri = `data:text/plain;base64,${base64Content}`