diff --git a/apps/sim/hooks/queries/kb/connectors.ts b/apps/sim/hooks/queries/kb/connectors.ts
index fd86f306e0a..1b737d8f2a5 100644
--- a/apps/sim/hooks/queries/kb/connectors.ts
+++ b/apps/sim/hooks/queries/kb/connectors.ts
@@ -88,6 +88,21 @@ async function fetchConnectorDetail(
   return result.data
 }
 
+/** Stop polling for initial sync after 2 minutes */
+const PENDING_SYNC_WINDOW_MS = 2 * 60 * 1000
+
+/**
+ * Checks if a connector is syncing or awaiting its first sync within the allowed window
+ */
+export function isConnectorSyncingOrPending(connector: ConnectorData): boolean {
+  if (connector.status === 'syncing') return true
+  return (
+    connector.status === 'active' &&
+    !connector.lastSyncAt &&
+    Date.now() - new Date(connector.createdAt).getTime() < PENDING_SYNC_WINDOW_MS
+  )
+}
+
 export function useConnectorList(knowledgeBaseId?: string) {
   return useQuery({
     queryKey: connectorKeys.list(knowledgeBaseId),
@@ -97,8 +112,8 @@ export function useConnectorList(knowledgeBaseId?: string) {
     placeholderData: keepPreviousData,
     refetchInterval: (query) => {
       const connectors = query.state.data
-      const hasSyncing = connectors?.some((c) => c.status === 'syncing')
-      return hasSyncing ? 3000 : false
+      if (!connectors?.length) return false
+      return connectors.some(isConnectorSyncingOrPending) ? 3000 : false
     },
   })
 }
diff --git a/apps/sim/lib/knowledge/connectors/sync-engine.ts b/apps/sim/lib/knowledge/connectors/sync-engine.ts
index a07005a95d9..efef605f52c 100644
--- a/apps/sim/lib/knowledge/connectors/sync-engine.ts
+++ b/apps/sim/lib/knowledge/connectors/sync-engine.ts
@@ -6,7 +6,7 @@ import {
   knowledgeConnectorSyncLog,
 } from '@sim/db/schema'
 import { createLogger } from '@sim/logger'
-import { and, eq, inArray, isNull, ne, sql } from 'drizzle-orm'
+import { and, eq, inArray, isNull, lt, ne, sql } from 'drizzle-orm'
 import { decryptApiKey } from '@/lib/api-key/crypto'
 import { getInternalApiBaseUrl } from '@/lib/core/utils/urls'
 import {
@@ -272,11 +272,12 @@ export async function executeSync(
   }
 
   const syncLogId = crypto.randomUUID()
+  const syncStartedAt = new Date()
   await db.insert(knowledgeConnectorSyncLog).values({
     id: syncLogId,
     connectorId,
     status: 'started',
-    startedAt: new Date(),
+    startedAt: syncStartedAt,
   })
 
   let syncExitedCleanly = false
@@ -536,19 +537,23 @@ export async function executeSync(
       throw new Error(`Knowledge base ${connector.knowledgeBaseId} was deleted during sync`)
     }
 
-    // Retry stuck documents that failed or never completed processing
+    // Retry stuck documents that failed or never completed processing.
+    // Only retry docs uploaded BEFORE this sync — docs added in the current sync
+    // are still processing asynchronously and would cause a duplicate processing race.
     const stuckDocs = await db
       .select({
         id: document.id,
         fileUrl: document.fileUrl,
         filename: document.filename,
         fileSize: document.fileSize,
+        mimeType: document.mimeType,
       })
       .from(document)
       .where(
         and(
           eq(document.connectorId, connectorId),
           inArray(document.processingStatus, ['pending', 'failed']),
+          lt(document.uploadedAt, syncStartedAt),
           eq(document.userExcluded, false),
           isNull(document.archivedAt),
           isNull(document.deletedAt)
@@ -565,7 +570,7 @@ export async function executeSync(
             filename: doc.filename ?? 'document.txt',
             fileUrl: doc.fileUrl ?? '',
             fileSize: doc.fileSize ?? 0,
-            mimeType: 'text/plain',
+            mimeType: doc.mimeType ?? 'text/plain',
           },
           {}
         ).catch((error) => {
diff --git a/apps/sim/lib/knowledge/documents/document-processor.ts b/apps/sim/lib/knowledge/documents/document-processor.ts
index 0185de495b1..72bf9007c9d 100644
--- a/apps/sim/lib/knowledge/documents/document-processor.ts
+++ b/apps/sim/lib/knowledge/documents/document-processor.ts
@@ -7,7 +7,7 @@ import { parseBuffer, parseFile } from '@/lib/file-parsers'
 import type { FileParseMetadata } from '@/lib/file-parsers/types'
 import { retryWithExponentialBackoff } from '@/lib/knowledge/documents/utils'
 import { StorageService } from '@/lib/uploads'
-import { isInternalFileUrl } from '@/lib/uploads/utils/file-utils'
+import { getExtensionFromMimeType, isInternalFileUrl } from '@/lib/uploads/utils/file-utils'
 import { downloadFileFromUrl } from '@/lib/uploads/utils/file-utils.server'
 import { mistralParserTool } from '@/tools/mistral/parser'
 
@@ -727,7 +727,7 @@ async function parseWithFileParser(fileUrl: string, filename: string, mimeType:
     if (fileUrl.startsWith('data:')) {
       content = await parseDataURI(fileUrl, filename, mimeType)
     } else if (fileUrl.startsWith('http')) {
-      const result = await parseHttpFile(fileUrl, filename)
+      const result = await parseHttpFile(fileUrl, filename, mimeType)
       content = result.content
       metadata = result.metadata || {}
     } else {
@@ -759,7 +759,10 @@ async function parseDataURI(fileUrl: string, filename: string, mimeType: string)
       : decodeURIComponent(base64Data)
   }
 
-  const extension = filename.split('.').pop()?.toLowerCase() || 'txt'
+  const extension =
+    (filename.includes('.') ? filename.split('.').pop()?.toLowerCase() : undefined) ||
+    getExtensionFromMimeType(mimeType) ||
+    'txt'
   const buffer = Buffer.from(base64Data, 'base64')
   const result = await parseBuffer(buffer, extension)
   return result.content
@@ -767,13 +770,17 @@ async function parseDataURI(fileUrl: string, filename: string, mimeType: string)
 
 async function parseHttpFile(
   fileUrl: string,
-  filename: string
+  filename: string,
+  mimeType?: string
 ): Promise<{ content: string; metadata?: FileParseMetadata }> {
   const buffer = await downloadFileWithTimeout(fileUrl)
 
-  const extension = filename.split('.').pop()?.toLowerCase()
+  let extension = filename.includes('.') ? filename.split('.').pop()?.toLowerCase() : undefined
+  if (!extension && mimeType) {
+    extension = getExtensionFromMimeType(mimeType) ?? undefined
+  }
   if (!extension) {
-    throw new Error(`Could not determine file extension: ${filename}`)
+    throw new Error(`Could not determine file type for: ${filename}`)
   }
 
   const result = await parseBuffer(buffer, extension)