feat: introduce API leveling, post_training, eval to v1alpha (#3449)

# What does this PR do?

Rather than have a single `LLAMA_STACK_VERSION`, we need to have a
`_V1`, `_V1ALPHA`, and `_V1BETA` constant.

This also necessitated addition of `level` to the `WebMethod` so that
routing can be handeled properly.


For backwards compat, the `v1` routes are being kept around and marked
as `deprecated`. When used, the server will log a deprecation warning.

Deprecation log:

<img width="1224" height="134" alt="Screenshot 2025-09-25 at 2 43 36 PM"
src="https://github.com/user-attachments/assets/0cc7c245-dafc-48f0-be99-269fb9a686f9"
/>

move:
1. post_training to `v1alpha` as it is under heavy development and not
near its final state
2. eval: job scheduling is not implemented. Relies heavily on the
datasetio API which is under development missing implementations of
specific routes indicating the structure of those routes might change.
Additionally eval depends on the `inference` API which is going to be
deprecated, eval will likely need a major API surface change to conform
to using completions properly

implements leveling in #3317 

note: integration tests will fail until the SDK is regenerated with
v1alpha/inference as opposed to v1/inference

## Test Plan

existing tests should pass with newly generated schema. Conformance will
also pass as these routes are not the ones we currently test for
stability

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

llama_stack/apis/agents/agents.py

@@ -27,6 +27,7 @@ from llama_stack.apis.inference import (
 )
 from llama_stack.apis.safety import SafetyViolation
 from llama_stack.apis.tools import ToolDef
+from llama_stack.apis.version import LLAMA_STACK_API_V1
 from llama_stack.schema_utils import json_schema_type, register_schema, webmethod
 
 from .openai_responses import (
@@ -481,7 +482,7 @@ class Agents(Protocol):
     - Agents can also use Memory to retrieve information from knowledge bases. See the RAG Tool and Vector IO APIs for more details.
     """
 
-    @webmethod(route="/agents", method="POST", descriptive_name="create_agent")
+    @webmethod(route="/agents", method="POST", descriptive_name="create_agent", level=LLAMA_STACK_API_V1)
     async def create_agent(
         self,
         agent_config: AgentConfig,
@@ -494,7 +495,10 @@ class Agents(Protocol):
         ...
 
     @webmethod(
-        route="/agents/{agent_id}/session/{session_id}/turn", method="POST", descriptive_name="create_agent_turn"
+        route="/agents/{agent_id}/session/{session_id}/turn",
+        method="POST",
+        descriptive_name="create_agent_turn",
+        level=LLAMA_STACK_API_V1,
     )
     async def create_agent_turn(
         self,
@@ -524,6 +528,7 @@ class Agents(Protocol):
         route="/agents/{agent_id}/session/{session_id}/turn/{turn_id}/resume",
         method="POST",
         descriptive_name="resume_agent_turn",
+        level=LLAMA_STACK_API_V1,
     )
     async def resume_agent_turn(
         self,
@@ -549,6 +554,7 @@ class Agents(Protocol):
     @webmethod(
         route="/agents/{agent_id}/session/{session_id}/turn/{turn_id}",
         method="GET",
+        level=LLAMA_STACK_API_V1,
     )
     async def get_agents_turn(
         self,
@@ -568,6 +574,7 @@ class Agents(Protocol):
     @webmethod(
         route="/agents/{agent_id}/session/{session_id}/turn/{turn_id}/step/{step_id}",
         method="GET",
+        level=LLAMA_STACK_API_V1,
     )
     async def get_agents_step(
         self,
@@ -586,7 +593,12 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/agents/{agent_id}/session", method="POST", descriptive_name="create_agent_session")
+    @webmethod(
+        route="/agents/{agent_id}/session",
+        method="POST",
+        descriptive_name="create_agent_session",
+        level=LLAMA_STACK_API_V1,
+    )
     async def create_agent_session(
         self,
         agent_id: str,
@@ -600,7 +612,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/agents/{agent_id}/session/{session_id}", method="GET")
+    @webmethod(route="/agents/{agent_id}/session/{session_id}", method="GET", level=LLAMA_STACK_API_V1)
     async def get_agents_session(
         self,
         session_id: str,
@@ -616,7 +628,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/agents/{agent_id}/session/{session_id}", method="DELETE")
+    @webmethod(route="/agents/{agent_id}/session/{session_id}", method="DELETE", level=LLAMA_STACK_API_V1)
     async def delete_agents_session(
         self,
         session_id: str,
@@ -629,7 +641,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/agents/{agent_id}", method="DELETE")
+    @webmethod(route="/agents/{agent_id}", method="DELETE", level=LLAMA_STACK_API_V1)
     async def delete_agent(
         self,
         agent_id: str,
@@ -640,7 +652,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/agents", method="GET")
+    @webmethod(route="/agents", method="GET", level=LLAMA_STACK_API_V1)
     async def list_agents(self, start_index: int | None = None, limit: int | None = None) -> PaginatedResponse:
         """List all agents.
 
@@ -650,7 +662,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/agents/{agent_id}", method="GET")
+    @webmethod(route="/agents/{agent_id}", method="GET", level=LLAMA_STACK_API_V1)
     async def get_agent(self, agent_id: str) -> Agent:
         """Describe an agent by its ID.
 
@@ -659,7 +671,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/agents/{agent_id}/sessions", method="GET")
+    @webmethod(route="/agents/{agent_id}/sessions", method="GET", level=LLAMA_STACK_API_V1)
     async def list_agent_sessions(
         self,
         agent_id: str,
@@ -682,7 +694,7 @@ class Agents(Protocol):
     #
     # Both of these APIs are inherently stateful.
 
-    @webmethod(route="/openai/v1/responses/{response_id}", method="GET")
+    @webmethod(route="/openai/v1/responses/{response_id}", method="GET", level=LLAMA_STACK_API_V1)
     async def get_openai_response(
         self,
         response_id: str,
@@ -694,7 +706,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/openai/v1/responses", method="POST")
+    @webmethod(route="/openai/v1/responses", method="POST", level=LLAMA_STACK_API_V1)
     async def create_openai_response(
         self,
         input: str | list[OpenAIResponseInput],
@@ -719,7 +731,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/openai/v1/responses", method="GET")
+    @webmethod(route="/openai/v1/responses", method="GET", level=LLAMA_STACK_API_V1)
     async def list_openai_responses(
         self,
         after: str | None = None,
@@ -737,7 +749,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/openai/v1/responses/{response_id}/input_items", method="GET")
+    @webmethod(route="/openai/v1/responses/{response_id}/input_items", method="GET", level=LLAMA_STACK_API_V1)
     async def list_openai_response_input_items(
         self,
         response_id: str,
@@ -759,7 +771,7 @@ class Agents(Protocol):
         """
         ...
 
-    @webmethod(route="/openai/v1/responses/{response_id}", method="DELETE")
+    @webmethod(route="/openai/v1/responses/{response_id}", method="DELETE", level=LLAMA_STACK_API_V1)
     async def delete_openai_response(self, response_id: str) -> OpenAIDeleteResponseObject:
         """Delete an OpenAI response by its ID.