fix(major::pr): re-architect instrumentation library

llama_stack/core/instrumentation.py

@@ -0,0 +1,33 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+"""Protocol for instrumentation providers."""
+
+from abc import abstractmethod
+
+from fastapi import FastAPI
+from pydantic import BaseModel, Field
+
+
+class InstrumentationProvider(BaseModel):
+    """
+    Base class for instrumentation providers.
+
+    Instrumentation providers add observability (tracing, metrics, logs) to the
+    application but don't expose API endpoints.
+    """
+
+    provider: str = Field(description="Provider identifier for discriminated unions")
+    config: BaseModel
+
+    @abstractmethod
+    def fastapi_middleware(self, app: FastAPI) -> None:
+        """
+        Inject middleware into the FastAPI application.
+
+        :param app: The FastAPI application to instrument
+        """
+        ...