feat: split API and provider specs into separate llama-stack-api pkg (#3895)

# What does this PR do?

Extract API definitions and provider specifications into a standalone
llama-stack-api package that can be published to PyPI independently of
the main llama-stack server.


see: https://github.com/llamastack/llama-stack/pull/2978 and
https://github.com/llamastack/llama-stack/pull/2978#issuecomment-3145115942

Motivation

External providers currently import from llama-stack, which overrides
the installed version and causes dependency conflicts. This separation
allows external providers to:

- Install only the type definitions they need without server
dependencies
- Avoid version conflicts with the installed llama-stack package
- Be versioned and released independently

This enables us to re-enable external provider module tests that were
previously blocked by these import conflicts.

Changes

- Created llama-stack-api package with minimal dependencies (pydantic,
jsonschema)
- Moved APIs, providers datatypes, strong_typing, and schema_utils
- Updated all imports from llama_stack.* to llama_stack_api.*
- Configured local editable install for development workflow
- Updated linting and type-checking configuration for both packages

Next Steps

- Publish llama-stack-api to PyPI
- Update external provider dependencies
- Re-enable external provider module tests


Pre-cursor PRs to this one:

- #4093 
- #3954 
- #4064 

These PRs moved key pieces _out_ of the Api pkg, limiting the scope of
change here.


relates to #3237 

## Test Plan

Package builds successfully and can be imported independently. All
pre-commit hooks pass with expected exclusions maintained.

---------

Signed-off-by: Charlie Doern <cdoern@redhat.com>

docs/docs/concepts/apis/external.mdx

@@ -58,7 +58,7 @@ External APIs must expose a `available_providers()` function in their module tha
 
 ```python
 # llama_stack_api_weather/api.py
-from llama_stack.providers.datatypes import Api, InlineProviderSpec, ProviderSpec
+from llama_stack_api import Api, InlineProviderSpec, ProviderSpec
 
 
 def available_providers() -> list[ProviderSpec]:
@@ -79,7 +79,7 @@ A Protocol class like so:
 # llama_stack_api_weather/api.py
 from typing import Protocol
 
-from llama_stack.schema_utils import webmethod
+from llama_stack_api import webmethod
 
 
 class WeatherAPI(Protocol):
@@ -151,13 +151,12 @@ __all__ = ["WeatherAPI", "available_providers"]
 # llama-stack-api-weather/src/llama_stack_api_weather/weather.py
 from typing import Protocol
 
-from llama_stack.providers.datatypes import (
+from llama_stack_api import (
     Api,
     ProviderSpec,
     RemoteProviderSpec,
+    webmethod,
 )
-from llama_stack.schema_utils import webmethod
-
 
 def available_providers() -> list[ProviderSpec]:
     return [

docs/docs/distributions/building_distro.mdx

@@ -65,7 +65,7 @@ external_providers_dir: /workspace/providers.d
 Inside `providers.d/custom_ollama/provider.py`, define `get_provider_spec()` so the CLI can discover dependencies:
 
 ```python
-from llama_stack.providers.datatypes import ProviderSpec
+from llama_stack_api.providers.datatypes import ProviderSpec
 
 
 def get_provider_spec() -> ProviderSpec:

docs/docs/providers/external/external-providers-guide.mdx

@@ -80,7 +80,7 @@ container_image: custom-vector-store:latest  # optional
 All providers must contain a `get_provider_spec` function in their `provider` module. This is a standardized structure that Llama Stack expects and is necessary for getting things such as the config class. The `get_provider_spec` method returns a structure identical to the `adapter`. An example function may look like:
 
 ```python
-from llama_stack.providers.datatypes import (
+from llama_stack_api.providers.datatypes import (
     ProviderSpec,
     Api,
     RemoteProviderSpec,

docs/docs/providers/vector_io/inline_sqlite-vec.mdx

@@ -153,7 +153,7 @@ description: |
   Example using RAGQueryConfig with different search modes:
 
   ```python
-  from llama_stack.apis.tools import RAGQueryConfig, RRFRanker, WeightedRanker
+  from llama_stack_api import RAGQueryConfig, RRFRanker, WeightedRanker
 
   # Vector search
   config = RAGQueryConfig(mode="vector", max_chunks=5)
@@ -358,7 +358,7 @@ Two ranker types are supported:
 Example using RAGQueryConfig with different search modes:
 
 ```python
-from llama_stack.apis.tools import RAGQueryConfig, RRFRanker, WeightedRanker
+from llama_stack_api import RAGQueryConfig, RRFRanker, WeightedRanker
 
 # Vector search
 config = RAGQueryConfig(mode="vector", max_chunks=5)

docs/openapi_generator/generate.py

@@ -16,7 +16,7 @@ import sys
 import fire
 import ruamel.yaml as yaml
 
-from llama_stack.apis.version import LLAMA_STACK_API_V1 # noqa: E402
+from llama_stack_api import LLAMA_STACK_API_V1 # noqa: E402
 from llama_stack.core.stack import LlamaStack  # noqa: E402
 
 from .pyopenapi.options import Options  # noqa: E402

docs/openapi_generator/pyopenapi/generator.py

@@ -16,27 +16,27 @@ from typing import Annotated, Any, Dict, get_args, get_origin, Set, Union
 
 from fastapi import UploadFile
 
-from llama_stack.apis.datatypes import Error
-from llama_stack.strong_typing.core import JsonType
-from llama_stack.strong_typing.docstring import Docstring, parse_type
-from llama_stack.strong_typing.inspection import (
+from llama_stack_api import (
+    Docstring,
+    Error,
+    JsonSchemaGenerator,
+    JsonType,
+    Schema,
+    SchemaOptions,
+    get_schema_identifier,
     is_generic_list,
     is_type_optional,
     is_type_union,
     is_unwrapped_body_param,
+    json_dump_string,
+    object_to_json,
+    parse_type,
+    python_type_to_name,
+    register_schema,
     unwrap_generic_list,
     unwrap_optional_type,
     unwrap_union_types,
 )
-from llama_stack.strong_typing.name import python_type_to_name
-from llama_stack.strong_typing.schema import (
-    get_schema_identifier,
-    JsonSchemaGenerator,
-    register_schema,
-    Schema,
-    SchemaOptions,
-)
-from llama_stack.strong_typing.serialization import json_dump_string, object_to_json
 from pydantic import BaseModel
 
 from .operations import (

docs/openapi_generator/pyopenapi/operations.py

@@ -11,19 +11,21 @@ import typing
 from dataclasses import dataclass
 from typing import Any, Callable, Dict, Iterable, Iterator, List, Optional, Tuple, Union
 
-from llama_stack.apis.version import LLAMA_STACK_API_V1, LLAMA_STACK_API_V1BETA, LLAMA_STACK_API_V1ALPHA
-
 from termcolor import colored
 
-from llama_stack.strong_typing.inspection import get_signature
-
 from typing import get_origin, get_args
 
 from fastapi import UploadFile
 from fastapi.params import File, Form
 from typing import Annotated
 
-from llama_stack.schema_utils import ExtraBodyField
+from llama_stack_api import (
+    ExtraBodyField,
+    LLAMA_STACK_API_V1,
+    LLAMA_STACK_API_V1ALPHA,
+    LLAMA_STACK_API_V1BETA,
+    get_signature,
+)
 
 
 def split_prefix(

docs/openapi_generator/pyopenapi/specification.py

@@ -9,7 +9,7 @@ import enum
 from dataclasses import dataclass
 from typing import Any, ClassVar, Dict, List, Optional, Union
 
-from llama_stack.strong_typing.schema import JsonType, Schema, StrictJsonType
+from llama_stack_api import JsonType, Schema, StrictJsonType
 
 URL = str
 

docs/openapi_generator/pyopenapi/utility.py

@@ -11,8 +11,7 @@ from pathlib import Path
 from typing import Any, List, Optional, TextIO, Union, get_type_hints, get_origin, get_args
 
 from pydantic import BaseModel
-from llama_stack.strong_typing.schema import object_to_json, StrictJsonType
-from llama_stack.strong_typing.inspection import is_unwrapped_body_param
+from llama_stack_api import StrictJsonType, is_unwrapped_body_param, object_to_json
 from llama_stack.core.resolver import api_protocol_map
 
 from .generator import Generator
@@ -165,12 +164,12 @@ def _validate_api_delete_method_returns_none(method) -> str | None:
         return "has no return type annotation"
 
     return_type = hints['return']
-    
+
     # Allow OpenAI endpoints to return response objects since they follow OpenAI specification
     method_name = getattr(method, '__name__', '')
     if method_name.__contains__('openai_'):
         return None
-    
+
     if return_type is not None and return_type is not type(None):
         return "does not return None where None is mandatory"