Archive Creation Fails with AttributeError on embedding Parameter

[wsargent]

Describe the bug

The /v1/archives POST endpoint (create archive) crashes with an AttributeError when using the embedding parameter. The endpoint code incorrectly tries to access .provider and .model attributes on a string value.

Error:

AttributeError: 'str' object has no attribute 'provider'

Please describe your setup

• How are you running Letta?
  • Docker (letta/letta:0.14.0)
• Describe your setup
  • OS: macOS (Darwin 25.1.0)
  • Docker command: docker compose up with the following configuration:

    letta:
      image: letta/letta:0.14.0
      ports:
        - 8283:8283
      environment:
        LETTA_PG_DB: letta
        LETTA_PG_USER: letta
        LETTA_PG_PASSWORD: letta
        LETTA_PG_HOST: pgvector_db
        LETTA_PG_PORT: 5432
        ANTHROPIC_API_KEY: $ANTHROPIC_API_KEY
        GEMINI_API_KEY: $GEMINI_API_KEY

Screenshots

Full stack trace:

letta-1     | Letta.letta.server.rest_api.middleware.logging - ERROR - Unhandled exception in request: AttributeError: 'str' object has no attribute 'provider'
letta-1     | Traceback (most recent call last):
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/middleware/base.py", line 151, in call_next
letta-1     |     message = await recv_stream.receive()
letta-1     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/anyio/streams/memory.py", line 126, in receive
letta-1     |     raise EndOfStream from None
letta-1     | anyio.EndOfStream
letta-1     |
letta-1     | During handling of the above exception, another exception occurred:
letta-1     |
letta-1     | Traceback (most recent call last):
letta-1     |   File "/app/letta/server/rest_api/middleware/logging.py", line 81, in dispatch
letta-1     |     response = await call_next(request)
letta-1     |                ^^^^^^^^^^^^^^^^^^^^^^^^
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/middleware/base.py", line 159, in call_next
letta-1     |     raise app_exc
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/middleware/base.py", line 144, in coro
letta-1     |     await self.app(scope, receive_or_disconnect, send_no_error)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/middleware/exceptions.py", line 63, in __call__
letta-1     |     await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
letta-1     |     raise exc
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
letta-1     |     await app(scope, receive, sender)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/routing.py", line 716, in __call__
letta-1     |     await self.middleware_stack(scope, receive, send)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/routing.py", line 736, in app
letta-1     |     await route.handle(scope, receive, send)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/routing.py", line 290, in handle
letta-1     |     await self.app(scope, receive, send)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/routing.py", line 78, in app
letta-1     |     await wrap_app_handling_exceptions(app, request)(scope, receive, send)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
letta-1     |     raise exc
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
letta-1     |     await app(scope, receive, sender)
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/starlette/routing.py", line 75, in app
letta-1     |     response = await f(request)
letta-1     |                ^^^^^^^^^^^^^^^^
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/fastapi/routing.py", line 302, in app
letta-1     |     raw_response = await run_endpoint_function(
letta-1     |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
letta-1     |   File "/app/.venv/lib/python3.11/site-packages/fastapi/routing.py", line 213, in run_endpoint_function
letta-1     |     return await dependant.call(**values)
letta-1     |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
letta-1     |   File "/app/letta/server/rest_api/routers/v1/archives.py", line 68, in create_archive
letta-1     |     handle = f"{archive.embedding.provider}/{archive.embedding.model}"
letta-1     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^
letta-1     | AttributeError: 'str' object has no attribute 'provider'

Additional context

• This affects Letta version 0.14.0
• Model used: letta/letta-free (free embedding model)
• The deprecated embedding_config parameter still works but requires constructing a full EmbeddingConfig object
• The bug prevents using the simpler string-based embedding parameter that was intended as the replacement

Root Cause

In letta/server/rest_api/routers/v1/archives.py:

# Line 30: embedding is defined as a string
class ArchiveCreateRequest(BaseModel):
    embedding: Optional[str] = Field(None, description="Embedding model handle for the archive")

# Lines 67-68: Code incorrectly treats it as an object
if embedding_config is None and archive.embedding is not None:
    handle = f"{archive.embedding.provider}/{archive.embedding.model}"  # ❌ Bug!

The embedding field is defined as Optional[str] (line 30), but the code on line 68 tries to access .provider and .model attributes as if it were an object.

Steps to Reproduce

Using the Letta Python client:

from letta_client import Letta

client = Letta(base_url="http://localhost:8283", token="your_token")

# This triggers the bug
archive = client.archives.create(
    name="test-archive",
    description="Test archive",
    embedding="letta/letta-free"
)

Expected Behavior

The archive should be created successfully using the string handle "letta/letta-free".

Suggested Fix

Since archive.embedding is already a string handle in the format "provider/model" (e.g., "letta/letta-free"), the code should use it directly:

Change line 68 in letta/server/rest_api/routers/v1/archives.py from:

handle = f"{archive.embedding.provider}/{archive.embedding.model}"

to:

handle = archive.embedding

Full corrected code block (lines 66-72):

embedding_config = archive.embedding_config
if embedding_config is None and archive.embedding is not None:
    handle = archive.embedding  # ✅ Fix: use the string directly
    embedding_config = await server.get_embedding_config_from_handle_async(
        handle=handle,
        actor=actor,
    )