diff --git a/letta/server/rest_api/routers/v1/folders.py b/letta/server/rest_api/routers/v1/folders.py
index 2c9a9552..6d3c953b 100644
--- a/letta/server/rest_api/routers/v1/folders.py
+++ b/letta/server/rest_api/routers/v1/folders.py
@@ -238,6 +238,7 @@ async def upload_file_to_folder(
     """
     Upload a file to a data folder.
     """
+
     # NEW: Cloud based file processing
     # Determine file's MIME type
     mimetypes.guess_type(file.filename)[0] or "application/octet-stream"
@@ -271,9 +272,28 @@ async def upload_file_to_folder(
 
     actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
 
-    folder = await server.source_manager.get_source_by_id(source_id=folder_id, actor=actor)
+    # Read file bytes once
+    file_bytes = await file.read()
 
-    content = await file.read()
+    # If enabled, delegate to Temporal workflow (Lettuce) and return its result
+    if settings.use_lettuce_for_file_uploads:
+        from letta.services.lettuce import LettuceClient
+
+        lettuce_client = await LettuceClient.create()
+        result = await lettuce_client.upload_file_to_folder(
+            folder_id=folder_id,
+            actor_id=actor.id,
+            file_name=file.filename,
+            content=file_bytes,
+            content_type=raw_ct or None,
+            duplicate_handling=duplicate_handling,
+            override_name=name,
+        )
+        if result is not None:
+            return result.file_metadata
+
+    folder = await server.source_manager.get_source_by_id(source_id=folder_id, actor=actor)
+    content = file_bytes
     file_size_mb = len(content) / (1024 * 1024)
     from letta.log import get_logger
 
diff --git a/letta/server/rest_api/routers/v1/sources.py b/letta/server/rest_api/routers/v1/sources.py
index f1e2f452..c2cfa290 100644
--- a/letta/server/rest_api/routers/v1/sources.py
+++ b/letta/server/rest_api/routers/v1/sources.py
@@ -251,9 +251,28 @@ async def upload_file_to_source(
 
     actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
 
-    source = await server.source_manager.get_source_by_id(source_id=source_id, actor=actor)
+    # Read file bytes once
+    file_bytes = await file.read()
 
-    content = await file.read()
+    # If enabled, delegate to Temporal workflow (Lettuce) and return its result
+    if settings.use_lettuce_for_file_uploads:
+        from letta.services.lettuce import LettuceClient
+
+        lettuce_client = await LettuceClient.create()
+        result = await lettuce_client.upload_file_to_folder(
+            folder_id=source_id,  # same underlying entity
+            actor_id=actor.id,
+            file_name=file.filename,
+            content=file_bytes,
+            content_type=raw_ct or None,
+            duplicate_handling=duplicate_handling,
+            override_name=name,
+        )
+        if result is not None:
+            return result.file_metadata
+
+    source = await server.source_manager.get_source_by_id(source_id=source_id, actor=actor)
+    content = file_bytes
     file_size_mb = len(content) / (1024 * 1024)
     from letta.log import get_logger
 
diff --git a/letta/services/lettuce/__init__.py b/letta/services/lettuce/__init__.py
index f8e75a73..adabc7eb 100644
--- a/letta/services/lettuce/__init__.py
+++ b/letta/services/lettuce/__init__.py
@@ -1,6 +1,3 @@
-try:
-    from .lettuce_client import LettuceClient
-except ImportError:
-    from .lettuce_client_base import LettuceClient
+from .lettuce_client import LettuceClient
 
 __all__ = ["LettuceClient"]
diff --git a/letta/services/lettuce/lettuce_client_base.py b/letta/services/lettuce/lettuce_client_base.py
index 5d9892e1..b31600b4 100644
--- a/letta/services/lettuce/lettuce_client_base.py
+++ b/letta/services/lettuce/lettuce_client_base.py
@@ -1,5 +1,6 @@
 from letta.constants import DEFAULT_MAX_STEPS
 from letta.schemas.agent import AgentState
+from letta.schemas.enums import DuplicateFileHandling
 from letta.schemas.letta_message import MessageType
 from letta.schemas.message import MessageCreate
 from letta.schemas.user import User
@@ -84,3 +85,17 @@ class LettuceClient:
             str | None: The ID of the run or None if client is not available.
         """
         return None
+
+    async def upload_file_to_folder(
+        self,
+        *,
+        folder_id: str,
+        actor_id: str,
+        file_name: str,
+        content: bytes,
+        content_type: str | None = None,
+        duplicate_handling: DuplicateFileHandling | None = None,
+        override_name: str | None = None,
+    ):
+        """Kick off upload workflow. Base client does nothing and returns None."""
+        return None
diff --git a/letta/settings.py b/letta/settings.py
index 9147f53f..e5061d2a 100644
--- a/letta/settings.py
+++ b/letta/settings.py
@@ -293,6 +293,8 @@ class Settings(BaseSettings):
     # experimental toggle
     use_vertex_structured_outputs_experimental: bool = False
     use_asyncio_shield: bool = True
+    # Gate using Temporal (Lettuce) for file uploads via folders endpoint
+    use_lettuce_for_file_uploads: bool = False
 
     # Database pool monitoring
     enable_db_pool_monitoring: bool = True  # Enable connection pool monitoring