diff --git a/sdk/agentserver/azure-ai-agentserver-core/CHANGELOG.md b/sdk/agentserver/azure-ai-agentserver-core/CHANGELOG.md
index 0327b674ca21..8a74f1a376ae 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/CHANGELOG.md
+++ b/sdk/agentserver/azure-ai-agentserver-core/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### Features Added
 
+- Added a shared `experimental` decorator for marking Agent Server preview feature surfaces with docstring notes and one-time runtime warnings. The resilient task primitive and Foundry storage public APIs are now marked experimental.
 - Added public `MiddlewareFactory` and `StreamContent` typing aliases for host middleware and streaming helpers.
 - Added `set_resilient_tasks_enabled` / `resilient_tasks_enabled` to `azure.ai.agentserver.core.tasks` — a process-global switch (default off) that force-enables the resilient `TaskManager`'s startup recovery scan even before any durable task is declared (useful when tasks are registered lazily after startup).
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/api.md b/sdk/agentserver/azure-ai-agentserver-core/api.md
index 4e174496469d..1bfd57ded9f1 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/api.md
+++ b/sdk/agentserver/azure-ai-agentserver-core/api.md
@@ -29,6 +29,14 @@ namespace azure.ai.agentserver.core
     def azure.ai.agentserver.core.end_span(span: Any, exc: Optional[BaseException] = None) -> None: ...
 
 
+    @overload
+    def azure.ai.agentserver.core.experimental(wrapped: type[T]) -> type[T]: ...
+
+
+    @overload
+    def azure.ai.agentserver.core.experimental(wrapped: Callable[P, T]) -> Callable[P, T]: ...
+
+
     def azure.ai.agentserver.core.flush_spans(timeout_millis: int = 5000) -> None: ...
 
 
@@ -207,6 +215,7 @@ namespace azure.ai.agentserver.core.storage
         def __init__(self, mapping: Mapping[str, Any]) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStateStore(FoundryStorageClient): implements AsyncContextManager 
         property name: str    # Read-only
 
@@ -292,6 +301,7 @@ namespace azure.ai.agentserver.core.storage
             ) -> StateStore: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStorageApiError(FoundryStorageError):
 
         def __init__(
@@ -303,6 +313,7 @@ namespace azure.ai.agentserver.core.storage
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStorageBadRequestError(FoundryStorageError):
 
         def __init__(
@@ -315,6 +326,7 @@ namespace azure.ai.agentserver.core.storage
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStorageClient: implements AsyncContextManager 
 
         def __init__(
@@ -330,6 +342,7 @@ namespace azure.ai.agentserver.core.storage
         async def aclose(self) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStorageConflictError(FoundryStorageBadRequestError):
 
         def __init__(
@@ -342,6 +355,7 @@ namespace azure.ai.agentserver.core.storage
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStorageEndpoint:
 
         def __init__(
@@ -373,6 +387,7 @@ namespace azure.ai.agentserver.core.storage
             ) -> str: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStorageError(Exception):
 
         def __init__(
@@ -384,6 +399,7 @@ namespace azure.ai.agentserver.core.storage
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStorageNotFoundError(FoundryStorageError):
 
         def __init__(
@@ -395,6 +411,7 @@ namespace azure.ai.agentserver.core.storage
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.storage.FoundryStoragePreconditionError(FoundryStorageError):
 
         def __init__(
@@ -591,9 +608,11 @@ namespace azure.ai.agentserver.core.tasks
         ) -> Callable[[Callable[[TaskContext[Input]], Awaitable[Output]]], MultiTurnTask[Input, Output]]: ...
 
 
+    @experimental
     def azure.ai.agentserver.core.tasks.resilient_tasks_enabled() -> bool: ...
 
 
+    @experimental
     def azure.ai.agentserver.core.tasks.set_resilient_tasks_enabled(value: bool = True) -> None: ...
 
 
@@ -618,6 +637,7 @@ namespace azure.ai.agentserver.core.tasks
         ) -> Callable[[Callable[[TaskContext[Input]], Awaitable[Output]]], Task[Input, Output]]: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.InputTooLarge(ValueError):
 
         def __init__(
@@ -627,6 +647,7 @@ namespace azure.ai.agentserver.core.tasks
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.LastInputIdPreconditionFailed(TaskPreconditionFailed):
 
         def __init__(
@@ -639,6 +660,7 @@ namespace azure.ai.agentserver.core.tasks
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.MultiTurnTask(Generic[Input, Output]):
         property name: str    # Read-only
 
@@ -677,6 +699,7 @@ namespace azure.ai.agentserver.core.tasks
             ) -> TaskRun[Output]: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.RetryPolicy:
 
         def __eq__(self, other: object) -> bool: ...
@@ -735,6 +758,7 @@ namespace azure.ai.agentserver.core.tasks
             ) -> bool: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.SteeringQueueFull(RuntimeError):
 
         def __init__(
@@ -744,6 +768,7 @@ namespace azure.ai.agentserver.core.tasks
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.Task(Generic[Input, Output]):
 
         def __init__(
@@ -775,6 +800,7 @@ namespace azure.ai.agentserver.core.tasks
             ) -> TaskRun[Output]: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskCancelled(Exception):
 
         def __init__(
@@ -786,6 +812,7 @@ namespace azure.ai.agentserver.core.tasks
         def __str__(self) -> str: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskConflictError(RuntimeError):
 
         def __init__(
@@ -796,6 +823,7 @@ namespace azure.ai.agentserver.core.tasks
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskContext(Generic[Input]):
         property pending_input_count: int    # Read-only
 
@@ -819,6 +847,7 @@ namespace azure.ai.agentserver.core.tasks
         async def exit_for_recovery(self) -> Any: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskDeferred(Exception):
 
         def __init__(
@@ -842,6 +871,7 @@ namespace azure.ai.agentserver.core.tasks
         key "type": Literal["exhausted_retries"]
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskFailed(Exception):
         error: Union[TaskErrorDict, TaskExhaustedRetriesErrorDict]
 
@@ -853,9 +883,11 @@ namespace azure.ai.agentserver.core.tasks
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskManagerNotInitialized(RuntimeError):
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskMetadata(MutableMapping): implements Collection 
 
         def __call__(self, name: Optional[str] = None) -> TaskMetadata: ...
@@ -922,6 +954,7 @@ namespace azure.ai.agentserver.core.tasks
         def values(self) -> ValuesView[Any]: ...
 
 
+    @experimental
     class azure.ai.agentserver.core.tasks.TaskRun(Generic[Output]): implements Awaitable 
         property is_queued: bool    # Read-only
         property metadata: TaskMetadata    # Read-only
diff --git a/sdk/agentserver/azure-ai-agentserver-core/api.metadata.yml b/sdk/agentserver/azure-ai-agentserver-core/api.metadata.yml
index 1ffcb576c382..c51fc2ac00ff 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/api.metadata.yml
+++ b/sdk/agentserver/azure-ai-agentserver-core/api.metadata.yml
@@ -1,3 +1,3 @@
-apiMdSha256: fd3b7bd1ae87d9b18719027594934c55d968973f159fbc8a5b416d227c67282c
+apiMdSha256: 39d46207ea0196162ea0f0969c6a855a2c49ffbb7348d9649db7b0ae1f02ea68
 parserVersion: 0.3.30
-pythonVersion: 3.12.10
+pythonVersion: 3.12.13
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/__init__.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/__init__.py
index 78d21fabd875..10cb683493c7 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/__init__.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/__init__.py
@@ -15,6 +15,7 @@
 from ._base import AgentServerHost
 from ._config import AgentConfig, resolve_state_subdir
 from ._errors import create_error_response
+from ._experimental import experimental
 from ._middleware import InboundRequestLoggingMiddleware
 from ._request_context import (
     FoundryAgentRequestContext,
@@ -49,6 +50,7 @@
     "create_error_response",
     "detach_context",
     "end_span",
+    "experimental",
     "flush_spans",
     "get_request_context",
     "record_error",
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/_experimental.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/_experimental.py
new file mode 100644
index 000000000000..ca8d06fa41c7
--- /dev/null
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/_experimental.py
@@ -0,0 +1,150 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+"""Experimental API marker for Agent Server public preview features."""
+
+from __future__ import annotations
+
+import functools
+import inspect
+import logging
+import os
+import sys
+from collections.abc import Callable
+from contextvars import ContextVar
+from typing import TypeVar, overload
+
+from typing_extensions import ParamSpec, TypeGuard
+
+DOCSTRING_TEMPLATE = ".. note::    {0} {1}\n\n"
+DOCSTRING_DEFAULT_INDENTATION = 8
+EXPERIMENTAL_CLASS_MESSAGE = "This is an experimental class,"
+EXPERIMENTAL_METHOD_MESSAGE = "This is an experimental method,"
+EXPERIMENTAL_LINK_MESSAGE = (
+    "and may change at any time. Please see https://aka.ms/azure-ai-agentserver-experimental "
+    "for more information."
+)
+DISABLE_EXPERIMENTAL_WARNING_ENV_VAR = "AZURE_AI_AGENTSERVER_DISABLE_EXPERIMENTAL_WARNING"
+_EXPERIMENTAL_CACHE_KEY_ATTR = "_azure_agentserver_experimental_cache_key"
+_EXPERIMENTAL_MESSAGE_ATTR = "_azure_agentserver_experimental_message"
+_EXPERIMENTAL_WRAPPED_INIT_ATTR = "_azure_agentserver_experimental_wrapped_init"
+
+_warning_cache: set[str] = set()
+_experimental_init_active: ContextVar[bool] = ContextVar("experimental_init_active", default=False)
+module_logger = logging.getLogger(__name__)
+
+P = ParamSpec("P")
+T = TypeVar("T")
+
+
+@overload
+def experimental(wrapped: type[T]) -> type[T]: ...
+
+
+@overload
+def experimental(wrapped: Callable[P, T]) -> Callable[P, T]: ...
+
+
+def experimental(wrapped: type[T] | Callable[P, T]) -> type[T] | Callable[P, T]:
+    """Add an experimental note and runtime warning to a class or function.
+
+    :param wrapped: Class or callable to mark as experimental.
+    :type wrapped: type[T] | Callable[P, T]
+    :return: The wrapped class or callable.
+    :rtype: type[T] | Callable[P, T]
+    """
+
+    def is_class(value: type[T] | Callable[P, T]) -> TypeGuard[type[T]]:
+        return inspect.isclass(value)
+
+    if is_class(wrapped):
+        return _add_class_docstring(wrapped)
+    if inspect.isfunction(wrapped):
+        return _add_function_docstring(wrapped)
+    return wrapped
+
+
+def _add_class_docstring(cls: type[T]) -> type[T]:
+    cache_key = f"class:{cls.__module__}.{cls.__qualname__}"
+    message = f"Class {cls.__module__}.{cls.__qualname__}: {EXPERIMENTAL_CLASS_MESSAGE} {EXPERIMENTAL_LINK_MESSAGE}"
+    setattr(cls, _EXPERIMENTAL_CACHE_KEY_ATTR, cache_key)
+    setattr(cls, _EXPERIMENTAL_MESSAGE_ATTR, message)
+
+    doc_string = DOCSTRING_TEMPLATE.format(EXPERIMENTAL_CLASS_MESSAGE, EXPERIMENTAL_LINK_MESSAGE)
+    if cls.__doc__:
+        cls.__doc__ = _add_note_to_docstring(cls.__doc__, doc_string)
+    else:
+        cls.__doc__ = doc_string + ">"
+
+    original_init = cls.__init__
+    if "__init__" not in cls.__dict__ or getattr(original_init, _EXPERIMENTAL_WRAPPED_INIT_ATTR, False):
+        return cls
+
+    def wrapped_init(self, *args, **kwargs):  # type: ignore[no-untyped-def]
+        runtime_cls = type(self)
+        runtime_cache_key = getattr(runtime_cls, _EXPERIMENTAL_CACHE_KEY_ATTR, cache_key)
+        runtime_message = getattr(runtime_cls, _EXPERIMENTAL_MESSAGE_ATTR, message)
+        active = _experimental_init_active.get()
+        if not active and not _should_skip_warning() and not _is_warning_cached(runtime_cache_key):
+            module_logger.warning(runtime_message)
+        if active:
+            return original_init(self, *args, **kwargs)
+        token = _experimental_init_active.set(True)
+        try:
+            return original_init(self, *args, **kwargs)
+        finally:
+            _experimental_init_active.reset(token)
+
+    if "__init__" in cls.__dict__ and inspect.isfunction(original_init):
+        wrapped_init = functools.wraps(original_init)(wrapped_init)
+    setattr(wrapped_init, _EXPERIMENTAL_WRAPPED_INIT_ATTR, True)
+
+    cls.__init__ = wrapped_init  # type: ignore[method-assign]
+    return cls
+
+
+def _add_function_docstring(func: Callable[P, T]) -> Callable[P, T]:
+    doc_string = DOCSTRING_TEMPLATE.format(EXPERIMENTAL_METHOD_MESSAGE, EXPERIMENTAL_LINK_MESSAGE)
+    if func.__doc__:
+        func.__doc__ = _add_note_to_docstring(func.__doc__, doc_string)
+    else:
+        func.__doc__ = doc_string + ">"
+
+    @functools.wraps(func)
+    def wrapped(*args: P.args, **kwargs: P.kwargs) -> T:
+        cache_key = f"function:{func.__module__}.{func.__qualname__}"
+        message = (
+            f"Method {func.__module__}.{func.__qualname__}: "
+            f"{EXPERIMENTAL_METHOD_MESSAGE} {EXPERIMENTAL_LINK_MESSAGE}"
+        )
+        if not _should_skip_warning() and not _is_warning_cached(cache_key):
+            module_logger.warning(message)
+        return func(*args, **kwargs)
+
+    return wrapped
+
+
+def _add_note_to_docstring(doc_string: str, note: str) -> str:
+    indent = _get_indentation_size(doc_string)
+    doc_string = doc_string.rjust(len(doc_string) + indent)
+    return note + doc_string
+
+
+def _get_indentation_size(doc_string: str) -> int:
+    lines = doc_string.expandtabs().splitlines()
+    indent = sys.maxsize
+    for line in lines[1:]:
+        stripped = line.lstrip()
+        if stripped:
+            indent = min(indent, len(line) - len(stripped))
+    return indent if indent < sys.maxsize else DOCSTRING_DEFAULT_INDENTATION
+
+
+def _should_skip_warning() -> bool:
+    return os.getenv(DISABLE_EXPERIMENTAL_WARNING_ENV_VAR, "false").lower() == "true"
+
+
+def _is_warning_cached(cache_key: str) -> bool:
+    if cache_key in _warning_cache:
+        return True
+    _warning_cache.add(cache_key)
+    return False
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_client.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_client.py
index bf33c482e752..ae1986f4ec2b 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_client.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_client.py
@@ -21,6 +21,7 @@
 from azure.core.pipeline import policies
 from azure.core.rest import AsyncHttpResponse, HttpRequest
 
+from azure.ai.agentserver.core._experimental import experimental
 from azure.ai.agentserver.core._platform_headers import PLATFORM_ERROR_TAG
 from azure.ai.agentserver.core._version import VERSION
 
@@ -34,6 +35,7 @@
 JSON_CONTENT_TYPE = "application/json; charset=utf-8"
 
 
+@experimental
 class FoundryStorageClient:
     """Base HTTP client for the Foundry storage API.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_endpoint.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_endpoint.py
index 8d32245a7c6c..8d6b62d93056 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_endpoint.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_endpoint.py
@@ -14,6 +14,7 @@
 
 from urllib.parse import quote as _url_quote
 
+from azure.ai.agentserver.core._experimental import experimental
 from azure.ai.agentserver.core._config import AgentConfig
 
 _DEFAULT_API_VERSION = "v1"
@@ -23,6 +24,7 @@ def _encode(value: str) -> str:
     return _url_quote(value, safe="")
 
 
+@experimental
 class FoundryStorageEndpoint:
     """Immutable Foundry storage endpoint configuration.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_errors.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_errors.py
index 8901cc3624b3..a3868bf76f94 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_errors.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_errors.py
@@ -9,6 +9,7 @@
 import json
 from typing import TYPE_CHECKING, Any, Union
 
+from azure.ai.agentserver.core._experimental import experimental
 from azure.ai.agentserver.core._platform_headers import PLATFORM_ERROR_TAG
 
 if TYPE_CHECKING:
@@ -17,6 +18,7 @@
     _AnyHttpResponse = Union[HttpResponse, AsyncHttpResponse]
 
 
+@experimental
 class FoundryStorageError(Exception):
     """Base class for errors returned by the Foundry storage API."""
 
@@ -33,10 +35,12 @@ def __init__(
         self.status_code = status_code
 
 
+@experimental
 class FoundryStorageNotFoundError(FoundryStorageError):
     """Raised when the requested resource does not exist (HTTP 404)."""
 
 
+@experimental
 class FoundryStorageBadRequestError(FoundryStorageError):
     """Raised for invalid-request errors (HTTP 400)."""
 
@@ -52,10 +56,12 @@ def __init__(
         self.param = param
 
 
+@experimental
 class FoundryStorageConflictError(FoundryStorageBadRequestError):
     """Raised when the requested create/update conflicts with an existing resource (HTTP 409)."""
 
 
+@experimental
 class FoundryStoragePreconditionError(FoundryStorageError):
     """Raised when an ``If-Match`` precondition fails on a single-item write."""
 
@@ -71,6 +77,7 @@ def __init__(
         self.current_etag = current_etag
 
 
+@experimental
 class FoundryStorageApiError(FoundryStorageError):
     """Raised for all other non-success HTTP responses."""
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_state.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_state.py
index 9f9ee11522de..c4066fcaa607 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_state.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/storage/_state.py
@@ -14,6 +14,8 @@
 from azure.core.credentials_async import AsyncTokenCredential
 from azure.core.rest import HttpRequest
 
+from azure.ai.agentserver.core._experimental import experimental
+
 from .._request_context import get_request_context
 from ._client import JSON_CONTENT_TYPE, FoundryStorageClient
 from ._endpoint import FoundryStorageEndpoint
@@ -54,6 +56,7 @@ def _validate_key(key: str) -> None:
         raise ValueError("key must be a non-empty string")
 
 
+@experimental
 class FoundryStateStore(FoundryStorageClient):
     """Developer-facing client for one explicit Foundry state store.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_context.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_context.py
index 39354cc84ed8..46112d058568 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_context.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_context.py
@@ -18,6 +18,8 @@
 import asyncio  # pylint: disable=do-not-import-asyncio
 from typing import Any, Callable, Generic, Literal, TypeVar
 
+from azure.ai.agentserver.core._experimental import experimental
+
 from ._metadata import TaskMetadata
 
 Input = TypeVar("Input")
@@ -64,6 +66,7 @@ class _ExitForRecovery:
     __slots__ = ()
 
 
+@experimental
 class TaskContext(Generic[Input]):  # pylint: disable=too-many-instance-attributes
     """The single parameter to a resilient task function.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_decorator.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_decorator.py
index ca9c799ad639..6d8ec9c836c0 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_decorator.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_decorator.py
@@ -34,6 +34,8 @@ async def my_task(ctx: TaskContext[MyInput]) -> MyOutput:
 
 import re
 
+from azure.ai.agentserver.core._experimental import experimental
+
 from ._client import TransportClassifiedError as _TransportClassifiedError
 from ._context import TaskContext
 from ._exceptions_internal import _HostedConflict, _translate_hosted_conflict
@@ -444,6 +446,7 @@ def __repr__(self) -> str:
         )
 
 
+@experimental
 class Task(Generic[Input, Output]):
     """A decorated resilient task function. Not callable directly.
 
@@ -1347,6 +1350,7 @@ def task(
 ]: ...
 
 
+@experimental
 def task(
     fn: Callable[..., Any] | None = None,
     *,
@@ -1551,6 +1555,7 @@ def _validate_multi_turn_task_kwargs(**kwargs: Any) -> None:
         )
 
 
+@experimental
 class MultiTurnTask(Generic[Input, Output]):  # pylint: disable=protected-access
     """A decorated multi-turn resilient task chain.
 
@@ -1775,6 +1780,7 @@ def multi_turn_task(
 ]: ...
 
 
+@experimental
 def multi_turn_task(
     fn: Callable[..., Any] | None = None,
     *,
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_enablement.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_enablement.py
index 892ef5e9f41f..84dae9c48963 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_enablement.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_enablement.py
@@ -25,9 +25,12 @@
     set_resilient_tasks_enabled(True)
 """
 
+from azure.ai.agentserver.core._experimental import experimental
+
 _RESILIENT_TASKS_ENABLED: bool = False
 
 
+@experimental
 def set_resilient_tasks_enabled(value: bool = True) -> None:
     """Force-enable (or clear) the resilient task recovery scan process-wide.
 
@@ -47,6 +50,7 @@ def set_resilient_tasks_enabled(value: bool = True) -> None:
     _RESILIENT_TASKS_ENABLED = bool(value)
 
 
+@experimental
 def resilient_tasks_enabled() -> bool:
     """Return whether the recovery scan was explicitly force-enabled.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_exceptions.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_exceptions.py
index 12204eec1f82..c24416dfe0a9 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_exceptions.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_exceptions.py
@@ -9,10 +9,13 @@
 transition, but discard them (the attribute is never set).
 """
 
-from typing import Any
 import inspect
+from typing import Any
+
+from azure.ai.agentserver.core._experimental import experimental
 
 
+@experimental
 class TaskFailed(Exception):
     """Raised when a resilient task function raises an unhandled exception.
 
@@ -46,6 +49,7 @@ def __init__(self, *args: Any, error: dict[str, Any] | None = None) -> None:
 )
 
 
+@experimental
 class TaskCancelled(Exception):
     """Raised when a resilient task is cancelled (: bare)."""
 
@@ -71,6 +75,7 @@ def __init__(self, task_id: str | None = None) -> None:
         super().__init__(f"Task {task_id!r} not found")
 
 
+@experimental
 class TaskConflictError(RuntimeError):
     """Raised when a task lifecycle conflict cannot be resolved.
 
@@ -101,6 +106,7 @@ def __init__(self, *args: Any, current_status: str | None = None) -> None:
 )
 
 
+@experimental
 class TaskManagerNotInitialized(RuntimeError):
     """Raised when a resilient-task operation is attempted with no installed manager.
 
@@ -123,6 +129,7 @@ def __init__(self, task_id: str, message: str | None = None) -> None:
         super().__init__(msg)
 
 
+@experimental
 class SteeringQueueFull(RuntimeError):
     """Raised when the steering pending-input queue is at capacity (: bare)."""
 
@@ -143,6 +150,7 @@ def __init__(self, task_id: str = "", message: str = "") -> None:
         super().__init__(message or "task precondition failed")
 
 
+@experimental
 class LastInputIdPreconditionFailed(TaskPreconditionFailed):
     """Raised when ``Task.start``'s ``if_last_input_id`` precondition is not met.
 
@@ -178,6 +186,7 @@ def __init__(  # pylint: disable=super-init-not-called,unused-argument
 )
 
 
+@experimental
 class InputTooLarge(ValueError):
     """Raised when an input's serialized size exceeds the per-input cap (: bare)."""
 
@@ -254,6 +263,7 @@ def __init__(self, task_id: str, current_count: int, max_count: int) -> None:
     from typing_extensions import Literal, TypedDict  # type: ignore[assignment]
 
 
+@experimental
 class TaskDeferred(Exception):
     """Raised when handler called ``ctx.exit_for_recovery``.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_metadata.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_metadata.py
index 3de256cab037..85d4b04da2d5 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_metadata.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_metadata.py
@@ -33,7 +33,9 @@
 import collections.abc
 import logging
 from collections.abc import Iterator
-from typing import Any, Awaitable, Callable, Optional
+from typing import Any, Awaitable, Callable, Dict, List, Optional, TypeAlias, Union
+
+from azure.ai.agentserver.core._experimental import experimental
 
 logger = logging.getLogger("azure.ai.agentserver.tasks")
 
@@ -46,6 +48,7 @@
 NamespaceFlushCallback = Callable[[Optional[str], dict[str, Any]], Awaitable[None]]
 
 
+@experimental
 class TaskMetadata(collections.abc.MutableMapping):
     """Mutable progress dict persisted to the task record's payload.
 
@@ -331,13 +334,6 @@ async def _do_flush_one(self) -> None:
 # Public type alias exported via tasks.__init__. TaskMetadata values
 # SHOULD be JSON-serializable; this alias documents the value space.
 
-from typing import Union, List, Dict  # pylint: disable=wrong-import-position
-
-try:
-    from typing import TypeAlias  # Python 3.10+
-except ImportError:  # pragma: no cover
-    from typing_extensions import TypeAlias  # type: ignore[assignment]
-
 # Recursive JSON type alias. Forward refs allow self-recursion.
 # Use ForwardRef-via-string for the recursive arms so this type-checks
 # on all Python versions, and the test's ForwardRef-detection logic
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_retry.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_retry.py
index 0ff49d1e58c4..f388825cbd67 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_retry.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_retry.py
@@ -13,6 +13,8 @@
 import random
 from datetime import timedelta
 
+from azure.ai.agentserver.core._experimental import experimental
+
 #: Spec 037 #11 — hard caps on the retry knobs. A misconfiguration must not
 # let a task turn retry unboundedly, so values outside these ranges are
 # rejected at construction (fail-fast, not clamped). A developer may still
@@ -23,6 +25,7 @@
 _MAX_RETRY_DELAY = timedelta(hours=1)
 
 
+@experimental
 class RetryPolicy:
     """Retry configuration for resilient tasks.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_run.py b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_run.py
index 8d9b1fae9414..c7d0a0c61cdc 100644
--- a/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_run.py
+++ b/sdk/agentserver/azure-ai-agentserver-core/azure/ai/agentserver/core/tasks/_run.py
@@ -23,6 +23,8 @@
 import asyncio  # pylint: disable=do-not-import-asyncio
 from typing import Any, Generic, TypeVar
 
+from azure.ai.agentserver.core._experimental import experimental
+
 from ._metadata import TaskMetadata
 
 Output = TypeVar("Output")
@@ -42,6 +44,7 @@ def _unwrap_result(res: Any) -> Any:
     return res
 
 
+@experimental
 class TaskRun(Generic[Output]):  # pylint: disable=too-many-instance-attributes
     """Handle to a running or completed resilient task.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-core/tests/test_experimental.py b/sdk/agentserver/azure-ai-agentserver-core/tests/test_experimental.py
new file mode 100644
index 000000000000..6d196af790f4
--- /dev/null
+++ b/sdk/agentserver/azure-ai-agentserver-core/tests/test_experimental.py
@@ -0,0 +1,145 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+import logging
+
+from azure.ai.agentserver.core import experimental
+from azure.ai.agentserver.core._experimental import (
+    DISABLE_EXPERIMENTAL_WARNING_ENV_VAR,
+    EXPERIMENTAL_CLASS_MESSAGE,
+    EXPERIMENTAL_LINK_MESSAGE,
+    EXPERIMENTAL_METHOD_MESSAGE,
+    _warning_cache,
+)
+from azure.ai.agentserver.core.tasks import multi_turn_task, resilient_tasks_enabled, task
+
+
+@experimental
+class ExperimentalClass:
+    """A test class."""
+
+    def __init__(self) -> None:
+        self.value = 1
+
+
+@experimental
+def experimental_function() -> bool:
+    """A test function."""
+    return True
+
+
+def _duplicate_init(self) -> None:
+    self.value = 1
+
+
+ExperimentalDuplicateA = experimental(
+    type("ExperimentalDuplicate", (), {"__module__": "test.module_a", "__init__": _duplicate_init})
+)
+ExperimentalDuplicateB = experimental(
+    type("ExperimentalDuplicate", (), {"__module__": "test.module_b", "__init__": _duplicate_init})
+)
+
+
+@experimental
+class ExperimentalBase:
+    """A test base class."""
+
+    def __init__(self) -> None:
+        self.value = 1
+
+
+@experimental
+class ExperimentalChild(ExperimentalBase):
+    """A test child class."""
+
+
+def test_experimental_decorator_on_class(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        ExperimentalClass()
+
+    assert ExperimentalClass.__doc__.startswith(".. note::")
+    assert EXPERIMENTAL_CLASS_MESSAGE in ExperimentalClass.__doc__
+    assert EXPERIMENTAL_LINK_MESSAGE in ExperimentalClass.__doc__
+    assert len(caplog.records) == 1
+    assert EXPERIMENTAL_CLASS_MESSAGE in caplog.records[0].message
+
+
+def test_experimental_decorator_on_function(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        assert experimental_function() is True
+
+    assert experimental_function.__doc__.startswith(".. note::")
+    assert EXPERIMENTAL_METHOD_MESSAGE in experimental_function.__doc__
+    assert EXPERIMENTAL_LINK_MESSAGE in experimental_function.__doc__
+    assert len(caplog.records) == 1
+    assert EXPERIMENTAL_METHOD_MESSAGE in caplog.records[0].message
+
+
+def test_experimental_decorator_no_duplicate_warnings(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        experimental_function()
+        experimental_function()
+
+    assert len(caplog.records) == 1
+
+
+def test_experimental_decorator_uses_qualified_cache_keys(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        ExperimentalDuplicateA()
+        ExperimentalDuplicateB()
+
+    assert len(caplog.records) == 2
+    assert "test.module_a.ExperimentalDuplicate" in caplog.records[0].message
+    assert "test.module_b.ExperimentalDuplicate" in caplog.records[1].message
+
+
+def test_experimental_decorator_only_warns_for_outermost_class(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        ExperimentalChild()
+
+    assert len(caplog.records) == 1
+    assert "ExperimentalChild" in caplog.records[0].message
+    assert "ExperimentalBase" not in caplog.records[0].message
+
+
+def test_experimental_decorator_env_var_suppresses_warning(monkeypatch, caplog) -> None:
+    _warning_cache.clear()
+    monkeypatch.setenv(DISABLE_EXPERIMENTAL_WARNING_ENV_VAR, "true")
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        experimental_function()
+
+    assert len(caplog.records) == 0
+
+
+def test_resilient_task_public_api_is_experimental(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        resilient_tasks_enabled()
+
+    assert resilient_tasks_enabled.__doc__.startswith(".. note::")
+    assert EXPERIMENTAL_METHOD_MESSAGE in resilient_tasks_enabled.__doc__
+    assert len(caplog.records) == 1
+
+
+def test_resilient_task_decorator_factories_are_experimental(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        task(name="test-task")
+        multi_turn_task(name="test-multi-turn-task")
+
+    assert task.__doc__.startswith(".. note::")
+    assert multi_turn_task.__doc__.startswith(".. note::")
+    assert len(caplog.records) == 2
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/CHANGELOG.md b/sdk/agentserver/azure-ai-agentserver-responses/CHANGELOG.md
index e38c86ddb51a..c0c301ae1804 100644
--- a/sdk/agentserver/azure-ai-agentserver-responses/CHANGELOG.md
+++ b/sdk/agentserver/azure-ai-agentserver-responses/CHANGELOG.md
@@ -10,6 +10,8 @@
 
 ### Features Added
 
+- Marked Foundry storage public APIs as experimental.
+- Raised the minimum `azure-ai-agentserver-core` dependency to `>=2.0.0b10` so the shared experimental decorator is always available.
 - Added the `azure.ai.agentserver.responses.aio` namespace with async `ResponseEventStream` convenience generators that use the same method names as the sync stream, such as `output_item_message()` and `output_item_compaction()`.
 - Added local `TypedDict` model contract generation for the Responses protocol, including generated type aliases, union aliases, and `py.typed` packaging support.
 - Added dict-native wire payload helpers and request validators for validating protocol payloads without depending on generated model internals.
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/api.md b/sdk/agentserver/azure-ai-agentserver-responses/api.md
index 3dea894ec80b..bd552e867886 100644
--- a/sdk/agentserver/azure-ai-agentserver-responses/api.md
+++ b/sdk/agentserver/azure-ai-agentserver-responses/api.md
@@ -186,6 +186,7 @@ namespace azure.ai.agentserver.responses
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.responses.FoundryApiError(FoundryStorageError):
 
         def __init__(
@@ -196,6 +197,7 @@ namespace azure.ai.agentserver.responses
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.responses.FoundryBadRequestError(FoundryStorageError):
 
         def __init__(
@@ -206,6 +208,7 @@ namespace azure.ai.agentserver.responses
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.responses.FoundryResourceNotFoundError(FoundryStorageError):
 
         def __init__(
@@ -216,6 +219,7 @@ namespace azure.ai.agentserver.responses
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.responses.FoundryStorageError(Exception):
 
         def __init__(
@@ -226,6 +230,7 @@ namespace azure.ai.agentserver.responses
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.responses.FoundryStorageProvider: implements AsyncContextManager 
 
         def __init__(
@@ -295,6 +300,7 @@ namespace azure.ai.agentserver.responses
             ) -> None: ...
 
 
+    @experimental
     class azure.ai.agentserver.responses.FoundryStorageSettings:
 
         def __init__(
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/api.metadata.yml b/sdk/agentserver/azure-ai-agentserver-responses/api.metadata.yml
index 6c892122a747..7d064563d670 100644
--- a/sdk/agentserver/azure-ai-agentserver-responses/api.metadata.yml
+++ b/sdk/agentserver/azure-ai-agentserver-responses/api.metadata.yml
@@ -1,3 +1,3 @@
-apiMdSha256: 2c3ff121746e6028ece71257bcd47d7421233e6f92f2d3f6612a03a5ca34735a
+apiMdSha256: 895b7475f68870f634124632b0bf1e85fcf9d04a7162da9f1d12b2c40c33d78c
 parserVersion: 0.3.30
-pythonVersion: 3.12.10
+pythonVersion: 3.11.15
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/_experimental.py b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/_experimental.py
new file mode 100644
index 000000000000..19d141fda5ef
--- /dev/null
+++ b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/_experimental.py
@@ -0,0 +1,153 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+"""Compatibility shim for the shared Agent Server experimental decorator."""
+
+from __future__ import annotations
+
+import functools
+import importlib
+import inspect
+import logging
+import os
+import sys
+from collections.abc import Callable
+from contextvars import ContextVar
+from typing import Any, TypeVar, overload
+
+from typing_extensions import ParamSpec, TypeGuard
+
+try:
+    _core_experimental_module: Any | None = importlib.import_module("azure.ai.agentserver.core._experimental")
+except ImportError:
+    _core_experimental_module = None
+
+P = ParamSpec("P")
+T = TypeVar("T")
+
+if _core_experimental_module is not None:
+    _core_experimental: Any = _core_experimental_module
+    DOCSTRING_TEMPLATE = _core_experimental.DOCSTRING_TEMPLATE
+    DOCSTRING_DEFAULT_INDENTATION = _core_experimental.DOCSTRING_DEFAULT_INDENTATION
+    EXPERIMENTAL_CLASS_MESSAGE = _core_experimental.EXPERIMENTAL_CLASS_MESSAGE
+    EXPERIMENTAL_METHOD_MESSAGE = _core_experimental.EXPERIMENTAL_METHOD_MESSAGE
+    EXPERIMENTAL_LINK_MESSAGE = _core_experimental.EXPERIMENTAL_LINK_MESSAGE
+    DISABLE_EXPERIMENTAL_WARNING_ENV_VAR = _core_experimental.DISABLE_EXPERIMENTAL_WARNING_ENV_VAR
+    _warning_cache = getattr(_core_experimental, "_warning_cache")
+    experimental = _core_experimental.experimental
+else:
+    DOCSTRING_TEMPLATE = ".. note::    {0} {1}\n\n"
+    DOCSTRING_DEFAULT_INDENTATION = 8
+    EXPERIMENTAL_CLASS_MESSAGE = "This is an experimental class,"
+    EXPERIMENTAL_METHOD_MESSAGE = "This is an experimental method,"
+    EXPERIMENTAL_LINK_MESSAGE = (
+        "and may change at any time. Please see https://aka.ms/azure-ai-agentserver-experimental "
+        "for more information."
+    )
+    DISABLE_EXPERIMENTAL_WARNING_ENV_VAR = "AZURE_AI_AGENTSERVER_DISABLE_EXPERIMENTAL_WARNING"
+    _EXPERIMENTAL_CACHE_KEY_ATTR = "_azure_agentserver_experimental_cache_key"
+    _EXPERIMENTAL_MESSAGE_ATTR = "_azure_agentserver_experimental_message"
+    _EXPERIMENTAL_WRAPPED_INIT_ATTR = "_azure_agentserver_experimental_wrapped_init"
+
+    _fallback_warning_cache: set[str] = set()
+    _experimental_init_active: ContextVar[bool] = ContextVar("experimental_init_active", default=False)
+    module_logger = logging.getLogger(__name__)
+
+    @overload
+    def _fallback_experimental(wrapped: type[T]) -> type[T]: ...
+
+    @overload
+    def _fallback_experimental(wrapped: Callable[P, T]) -> Callable[P, T]: ...
+
+    def _fallback_experimental(wrapped: type[T] | Callable[P, T]) -> type[T] | Callable[P, T]:
+        def is_class(value: type[T] | Callable[P, T]) -> TypeGuard[type[T]]:
+            return inspect.isclass(value)
+
+        if is_class(wrapped):
+            return _add_class_docstring(wrapped)
+        if inspect.isfunction(wrapped):
+            return _add_function_docstring(wrapped)
+        return wrapped
+
+    def _add_class_docstring(cls: type[T]) -> type[T]:
+        cache_key = f"class:{cls.__module__}.{cls.__qualname__}"
+        message = f"Class {cls.__module__}.{cls.__qualname__}: {EXPERIMENTAL_CLASS_MESSAGE} {EXPERIMENTAL_LINK_MESSAGE}"
+        setattr(cls, _EXPERIMENTAL_CACHE_KEY_ATTR, cache_key)
+        setattr(cls, _EXPERIMENTAL_MESSAGE_ATTR, message)
+
+        doc_string = DOCSTRING_TEMPLATE.format(EXPERIMENTAL_CLASS_MESSAGE, EXPERIMENTAL_LINK_MESSAGE)
+        if cls.__doc__:
+            cls.__doc__ = _add_note_to_docstring(cls.__doc__, doc_string)
+        else:
+            cls.__doc__ = doc_string + ">"
+
+        original_init = cls.__init__
+        if "__init__" not in cls.__dict__ or getattr(original_init, _EXPERIMENTAL_WRAPPED_INIT_ATTR, False):
+            return cls
+
+        def wrapped_init(self, *args, **kwargs):  # type: ignore[no-untyped-def]
+            runtime_cls = type(self)
+            runtime_cache_key = getattr(runtime_cls, _EXPERIMENTAL_CACHE_KEY_ATTR, cache_key)
+            runtime_message = getattr(runtime_cls, _EXPERIMENTAL_MESSAGE_ATTR, message)
+            active = _experimental_init_active.get()
+            if not active and not _should_skip_warning() and not _is_warning_cached(runtime_cache_key):
+                module_logger.warning(runtime_message)
+            if active:
+                return original_init(self, *args, **kwargs)
+            token = _experimental_init_active.set(True)
+            try:
+                return original_init(self, *args, **kwargs)
+            finally:
+                _experimental_init_active.reset(token)
+
+        if "__init__" in cls.__dict__ and inspect.isfunction(original_init):
+            wrapped_init = functools.wraps(original_init)(wrapped_init)
+        setattr(wrapped_init, _EXPERIMENTAL_WRAPPED_INIT_ATTR, True)
+
+        cls.__init__ = wrapped_init  # type: ignore[method-assign]
+        return cls
+
+    def _add_function_docstring(func: Callable[P, T]) -> Callable[P, T]:
+        doc_string = DOCSTRING_TEMPLATE.format(EXPERIMENTAL_METHOD_MESSAGE, EXPERIMENTAL_LINK_MESSAGE)
+        if func.__doc__:
+            func.__doc__ = _add_note_to_docstring(func.__doc__, doc_string)
+        else:
+            func.__doc__ = doc_string + ">"
+
+        @functools.wraps(func)
+        def wrapped(*args: P.args, **kwargs: P.kwargs) -> T:
+            cache_key = f"function:{func.__module__}.{func.__qualname__}"
+            message = (
+                f"Method {func.__module__}.{func.__qualname__}: "
+                f"{EXPERIMENTAL_METHOD_MESSAGE} {EXPERIMENTAL_LINK_MESSAGE}"
+            )
+            if not _should_skip_warning() and not _is_warning_cached(cache_key):
+                module_logger.warning(message)
+            return func(*args, **kwargs)
+
+        return wrapped
+
+    def _add_note_to_docstring(doc_string: str, note: str) -> str:
+        indent = _get_indentation_size(doc_string)
+        doc_string = doc_string.rjust(len(doc_string) + indent)
+        return note + doc_string
+
+    def _get_indentation_size(doc_string: str) -> int:
+        lines = doc_string.expandtabs().splitlines()
+        indent = sys.maxsize
+        for line in lines[1:]:
+            stripped = line.lstrip()
+            if stripped:
+                indent = min(indent, len(line) - len(stripped))
+        return indent if indent < sys.maxsize else DOCSTRING_DEFAULT_INDENTATION
+
+    def _should_skip_warning() -> bool:
+        return os.getenv(DISABLE_EXPERIMENTAL_WARNING_ENV_VAR, "false").lower() == "true"
+
+    def _is_warning_cached(cache_key: str) -> bool:
+        if cache_key in _fallback_warning_cache:
+            return True
+        _fallback_warning_cache.add(cache_key)
+        return False
+
+    _warning_cache = _fallback_warning_cache
+    experimental = _fallback_experimental
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_errors.py b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_errors.py
index 62972d8ca9d3..32bac6788d58 100644
--- a/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_errors.py
+++ b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_errors.py
@@ -11,10 +11,13 @@
     PLATFORM_ERROR_TAG,
 )
 
+from .._experimental import experimental
+
 if TYPE_CHECKING:
     from azure.core.rest import HttpResponse
 
 
+@experimental
 class FoundryStorageError(Exception):
     """Base class for errors returned by the Foundry storage API."""
 
@@ -29,14 +32,17 @@ def __init__(
         self.response_body = response_body
 
 
+@experimental
 class FoundryResourceNotFoundError(FoundryStorageError):
     """Raised when the requested resource does not exist (HTTP 404)."""
 
 
+@experimental
 class FoundryBadRequestError(FoundryStorageError):
     """Raised for invalid-request or conflict errors (HTTP 400, 409)."""
 
 
+@experimental
 class FoundryApiError(FoundryStorageError):
     """Raised for all other non-success HTTP responses."""
 
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_provider.py b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_provider.py
index 0675f33f0843..7199bd0f265f 100644
--- a/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_provider.py
+++ b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_provider.py
@@ -30,6 +30,7 @@
     serialize_response,
 )
 from ._foundry_settings import FoundryStorageSettings
+from .._experimental import experimental
 
 if TYPE_CHECKING:
     from .._response_context import PlatformContext
@@ -134,6 +135,7 @@ def _apply_platform_headers(request: HttpRequest, context: PlatformContext | Non
         request.headers[FOUNDRY_CALL_ID] = context.call_id
 
 
+@experimental
 class FoundryStorageProvider:
     """An HTTP-backed response storage provider that persists data via the Foundry storage API.
 
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_settings.py b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_settings.py
index 1923b9a63e91..7dff3e79bf12 100644
--- a/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_settings.py
+++ b/sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/store/_foundry_settings.py
@@ -8,6 +8,8 @@
 
 from azure.ai.agentserver.core import AgentConfig
 
+from .._experimental import experimental
+
 _API_VERSION = "v1"
 
 
@@ -15,6 +17,7 @@ def _encode(value: str) -> str:
     return _url_quote(value, safe="")
 
 
+@experimental
 class FoundryStorageSettings:
     """Immutable runtime configuration for :class:`FoundryStorageProvider`."""
 
diff --git a/sdk/agentserver/azure-ai-agentserver-responses/tests/test_experimental.py b/sdk/agentserver/azure-ai-agentserver-responses/tests/test_experimental.py
new file mode 100644
index 000000000000..4c389306ba13
--- /dev/null
+++ b/sdk/agentserver/azure-ai-agentserver-responses/tests/test_experimental.py
@@ -0,0 +1,23 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+import logging
+
+from azure.ai.agentserver.responses import FoundryStorageSettings, ResponsesAgentServerHost
+from azure.ai.agentserver.responses._experimental import EXPERIMENTAL_CLASS_MESSAGE, _warning_cache, experimental
+
+
+def test_foundry_storage_settings_is_experimental(caplog) -> None:
+    _warning_cache.clear()
+
+    with caplog.at_level(logging.WARNING, logger=experimental.__module__):
+        FoundryStorageSettings.from_endpoint("https://example.foundry.azure.com")
+
+    assert FoundryStorageSettings.__doc__.startswith(".. note::")
+    assert EXPERIMENTAL_CLASS_MESSAGE in FoundryStorageSettings.__doc__
+    assert len(caplog.records) == 1
+    assert EXPERIMENTAL_CLASS_MESSAGE in caplog.records[0].message
+
+
+def test_protocol_hosts_are_not_marked_experimental() -> None:
+    assert not ResponsesAgentServerHost.__doc__.startswith(".. note::")