diff --git a/python/PACKAGE_STATUS.md b/python/PACKAGE_STATUS.md
index d14af5d0606..ff95b8368d2 100644
--- a/python/PACKAGE_STATUS.md
+++ b/python/PACKAGE_STATUS.md
@@ -70,9 +70,8 @@ listed below.
   `create_agent_hooks_middleware_from_emitter` from `agent_framework/_agent_hooks.py`,
   the AGENT-HOOKS-0.1 enforcement middleware bundle, and the `MiddlewareBundle`
   container from `agent_framework/_middleware.py` that both factories produce
-  (`MiddlewareBundle` itself needs no extra). Requires the opt-in
-  `agent-framework-core[agent-hooks]` extra (`agent-hooks-sdk`), which is deliberately
-  not part of `agent-framework-core[all]`. Known limitation: service-side (hosted) tool
+  (`MiddlewareBundle` itself needs no optional dependency). Requires installing the
+  `agent-hooks-sdk` package separately. Known limitation: service-side (hosted) tool
   execution never passes through the framework's function-invocation seam, so the
   `pre_tool_call`/`post_tool_call` points cannot intercept it; hosted tool calls and
   outputs are surfaced in the `post_model_call` content projection instead.
diff --git a/python/packages/core/agent_framework/_agent_hooks.py b/python/packages/core/agent_framework/_agent_hooks.py
index ea5ff016e68..ea27801f5aa 100644
--- a/python/packages/core/agent_framework/_agent_hooks.py
+++ b/python/packages/core/agent_framework/_agent_hooks.py
@@ -93,7 +93,7 @@
 
 The ``agent-hooks-sdk`` dependency is optional: importing this module (and the lazy root
 exports) works without it, and the factories raise a descriptive ``ModuleNotFoundError``
-when the SDK is missing. Install it via ``pip install agent-framework-core[agent-hooks]``.
+when the SDK is missing. Install it via ``pip install agent-hooks-sdk``.
 """
 
 from __future__ import annotations
@@ -162,7 +162,7 @@
 
 _SDK_MISSING_MESSAGE = (
     "The agent-hooks middleware requires the optional `agent-hooks-sdk` package. "
-    "Please install `agent-framework-core[agent-hooks]` (or `agent-hooks-sdk`)."
+    "Please install it with `pip install agent-hooks-sdk`."
 )
 
 _TRIO_REQUIRED_MESSAGE = (
@@ -191,7 +191,7 @@ def _require_sdk() -> None:
     """Import the SDK surface this module uses at runtime, with a helpful install hint.
 
     Only a genuinely missing ``agent_hooks`` package is translated into the
-    install-the-extra message; anything else (a broken installation, an incompatible
+    SDK installation message; anything else (a broken installation, an incompatible
     SDK version missing symbols, a failing transitive import) propagates unchanged so
     real breakage is not masked as a missing extra.
     """
diff --git a/python/packages/core/agent_framework/_agents.py b/python/packages/core/agent_framework/_agents.py
index f6224421343..ae594af4915 100644
--- a/python/packages/core/agent_framework/_agents.py
+++ b/python/packages/core/agent_framework/_agents.py
@@ -31,6 +31,7 @@
     FunctionInvocationContext,
     MiddlewareTypes,
     _as_middleware_list,  # pyright: ignore[reportPrivateUsage]
+    _copy_middleware_sequence,  # pyright: ignore[reportPrivateUsage]
     categorize_middleware,
 )
 from ._serialization import SerializationMixin
@@ -439,7 +440,7 @@ def __init__(
         name: str | None = None,
         description: str | None = None,
         context_providers: Sequence[ContextProvider] | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         additional_properties: MutableMapping[str, Any] | None = None,
     ) -> None:
         """Initialize a BaseAgent instance.
@@ -450,10 +451,8 @@ def __init__(
             name: The name of the agent, can be None.
             description: The description of the agent.
             context_providers: Context providers to include during agent invocation.
-            middleware: List of middleware, or a single middleware object (including a
-                ``MiddlewareBundle``) which is treated as a one-element list. The
-                constructor copies the sequence; assign to or mutate the
-                ``middleware`` attribute for post-construction changes.
+            middleware: List of middleware. The constructor copies the sequence; assign
+                to or mutate the ``middleware`` attribute for post-construction changes.
             additional_properties: Additional properties set on the agent.
         """
         if id is None:
@@ -462,11 +461,8 @@ def __init__(
         self.name = name
         self.description = description
         self.context_providers: list[ContextProvider] = list(context_providers or [])
-        # Canonicalize storage: the bare-source rule (a single middleware object or a
-        # MiddlewareBundle is one element) is owned by _as_middleware_list; storing a
-        # normalized list keeps the declared attribute type honest.
         self.middleware: list[MiddlewareTypes] | None = (
-            _as_middleware_list(middleware) if middleware is not None else None
+            _copy_middleware_sequence(middleware) if middleware is not None else None
         )
         self.additional_properties: dict[str, Any] = cast(dict[str, Any], additional_properties or {})
 
@@ -819,7 +815,7 @@ def __init__(
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         default_options: OptionsCoT | None = None,
         context_providers: Sequence[ContextProvider] | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         require_per_service_call_history_persistence: bool = False,
         compaction_strategy: CompactionStrategy | None = None,
         tokenizer: TokenizerProtocol | None = None,
@@ -838,8 +834,6 @@ def __init__(
             description: A brief description of the agent's purpose.
             context_providers: Context providers to include during agent invocation.
             middleware: List of middleware to intercept agent and function invocations.
-                A single middleware object (including a ``MiddlewareBundle``) is
-                treated as a one-element list.
             require_per_service_call_history_persistence: When True (and a HistoryProvider is
                 present), the provider always persists history via per-service-call middleware,
                 regardless of whether the client stores history server-side. If the client does
@@ -1808,7 +1802,7 @@ def run(
         *,
         stream: Literal[False] = ...,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[ResponseModelBoundT],
         compaction_strategy: CompactionStrategy | None = None,
@@ -1824,7 +1818,7 @@ def run(
         *,
         stream: Literal[False] = ...,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: OptionsCoT | ChatOptions[None] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -1840,7 +1834,7 @@ def run(
         *,
         stream: Literal[True],
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: OptionsCoT | ChatOptions[Any] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -1855,7 +1849,7 @@ def run(
         *,
         stream: bool = False,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: OptionsCoT | ChatOptions[Any] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -1893,7 +1887,7 @@ def __init__(
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         default_options: OptionsCoT | None = None,
         context_providers: Sequence[ContextProvider] | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         require_per_service_call_history_persistence: bool = False,
         compaction_strategy: CompactionStrategy | None = None,
         tokenizer: TokenizerProtocol | None = None,
diff --git a/python/packages/core/agent_framework/_clients.py b/python/packages/core/agent_framework/_clients.py
index d4b758af26f..6119d3dcd3e 100644
--- a/python/packages/core/agent_framework/_clients.py
+++ b/python/packages/core/agent_framework/_clients.py
@@ -578,7 +578,7 @@ def as_agent(
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         default_options: OptionsCoT | Mapping[str, Any] | None = None,
         context_providers: Sequence[Any] | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         require_per_service_call_history_persistence: bool = False,
         compaction_strategy: CompactionStrategy | None = None,
         tokenizer: TokenizerProtocol | None = None,
diff --git a/python/packages/core/agent_framework/_harness/_agent.py b/python/packages/core/agent_framework/_harness/_agent.py
index c3cdea84b26..36c3fcbc2d8 100644
--- a/python/packages/core/agent_framework/_harness/_agent.py
+++ b/python/packages/core/agent_framework/_harness/_agent.py
@@ -20,6 +20,7 @@
 from .._clients import SupportsShellTool, SupportsWebSearchTool
 from .._compaction import CompactionProvider, ContextWindowCompactionStrategy
 from .._feature_stage import ExperimentalFeature, warn_experimental_feature
+from .._middleware import _copy_middleware_sequence  # pyright: ignore[reportPrivateUsage]
 from .._sessions import ContextProvider, HistoryProvider, InMemoryHistoryProvider, MessageInjectionMiddleware
 from .._skills import SkillsProvider
 from .._telemetry import FeatureIndex, mark_feature_used
@@ -347,7 +348,7 @@ def create_harness_agent(
     loop_max_iterations: int | None = DEFAULT_MAX_ITERATIONS,
     otel_provider_name: str | None = None,
     context_providers: Sequence[ContextProvider] | None = None,
-    middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+    middleware: Sequence[MiddlewareTypes] | None = None,
     default_options: Mapping[str, Any] | None = None,
 ) -> Agent[OptionsCoT]:
     """Create a pre-configured agent with batteries included.
@@ -669,11 +670,8 @@ def create_harness_agent(
     # Message injection is always on. It is a no-op when no messages are queued for the session,
     # so there is no opt-out.
     assembled_middleware.append(MessageInjectionMiddleware())
-    # Bare-source normalization (a single middleware object or a MiddlewareBundle is
-    # one element) is owned by _as_middleware_list.
-    from .._middleware import _as_middleware_list  # pyright: ignore[reportPrivateUsage]
-
-    assembled_middleware.extend(_as_middleware_list(middleware))
+    if middleware is not None:
+        assembled_middleware.extend(_copy_middleware_sequence(middleware))
 
     agent = Agent(
         client,
diff --git a/python/packages/core/agent_framework/_harness/_agent.pyi b/python/packages/core/agent_framework/_harness/_agent.pyi
index c5a1bf00298..0c561f92358 100644
--- a/python/packages/core/agent_framework/_harness/_agent.pyi
+++ b/python/packages/core/agent_framework/_harness/_agent.pyi
@@ -89,6 +89,6 @@ def create_harness_agent(
     loop_max_iterations: int | None = DEFAULT_MAX_ITERATIONS,
     otel_provider_name: str | None = None,
     context_providers: Sequence[ContextProvider] | None = None,
-    middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+    middleware: Sequence[MiddlewareTypes] | None = None,
     default_options: Mapping[str, Any] | None = None,
 ) -> Agent[OptionsCoT]: ...
diff --git a/python/packages/core/agent_framework/_middleware.py b/python/packages/core/agent_framework/_middleware.py
index 45a3dcbf823..64c82104f5f 100644
--- a/python/packages/core/agent_framework/_middleware.py
+++ b/python/packages/core/agent_framework/_middleware.py
@@ -828,6 +828,15 @@ def __repr__(self) -> str:
 )
 
 
+def _copy_middleware_sequence(source: object | None) -> list[MiddlewareTypes]:
+    """Validate and copy a middleware sequence."""
+    if source is None:
+        return []
+    if isinstance(source, (str, bytes)) or not isinstance(source, Sequence):
+        raise TypeError("middleware must be a non-string sequence of middleware.")
+    return list(cast("Sequence[MiddlewareTypes]", source))
+
+
 def agent_middleware(func: AgentMiddlewareCallable) -> AgentMiddlewareCallable:
     """Decorator to mark a function as agent middleware.
 
@@ -1425,14 +1434,15 @@ class AgentMiddlewareLayer:
     def __init__(
         self,
         *args: Any,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         **kwargs: Any,
     ) -> None:
-        middleware_list = categorize_middleware(middleware)
+        middleware_sequence = _copy_middleware_sequence(middleware) if middleware is not None else None
+        middleware_list = categorize_middleware(middleware_sequence)
         self.agent_middleware = middleware_list["agent"]
         self._cached_agent_middleware_pipeline: AgentMiddlewarePipeline | None = None
         # Pass middleware to super so BaseAgent can store it for dynamic rebuild
-        super().__init__(*args, middleware=middleware, **kwargs)  # type: ignore[call-arg]
+        super().__init__(*args, middleware=middleware_sequence, **kwargs)  # type: ignore[call-arg]
         # Note: We intentionally don't extend client's middleware lists here.
         # Chat and function middleware is passed to the chat client at runtime via kwargs
         # in AgentMiddlewareLayer.run(), where it's properly combined with run-level middleware.
@@ -1456,7 +1466,7 @@ def run(
         *,
         stream: Literal[False] = ...,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[ResponseModelBoundT],
         compaction_strategy: CompactionStrategy | None = None,
@@ -1472,7 +1482,7 @@ def run(
         *,
         stream: Literal[False] = ...,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[None] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -1488,7 +1498,7 @@ def run(
         *,
         stream: Literal[True],
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[Any] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -1503,7 +1513,7 @@ def run(
         *,
         stream: bool = False,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[Any] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -1512,14 +1522,13 @@ def run(
         client_kwargs: Mapping[str, Any] | None = None,
     ) -> Awaitable[AgentResponse[Any]] | ResponseStream[AgentResponseUpdate, AgentResponse[Any]]:
         """MiddlewareTypes-enabled unified run method."""
-        # Re-categorize self.middleware at runtime to support dynamic changes. The raw
-        # attribute is passed straight through: categorize_middleware owns the rule
-        # that a bare single source (one middleware object or a MiddlewareBundle
-        # assigned directly to the attribute) is one element — never silently dropped.
+        base_middleware = getattr(self, "middleware", None)
         base_middleware_list = categorize_middleware(
-            cast("MiddlewareTypes | Sequence[MiddlewareTypes] | None", getattr(self, "middleware", None))
+            _copy_middleware_sequence(base_middleware) if base_middleware is not None else None
+        )
+        run_middleware_list = categorize_middleware(
+            _copy_middleware_sequence(middleware) if middleware is not None else None
         )
-        run_middleware_list = categorize_middleware(middleware)
         pipeline = self._get_agent_middleware_pipeline([*base_middleware_list["agent"], *run_middleware_list["agent"]])
 
         # Combine base and run-level function/chat middleware for forwarding to chat client
diff --git a/python/packages/core/agent_framework/observability.py b/python/packages/core/agent_framework/observability.py
index acfe8019c3a..9cecdc57fca 100644
--- a/python/packages/core/agent_framework/observability.py
+++ b/python/packages/core/agent_framework/observability.py
@@ -2542,7 +2542,7 @@ def run(
         *,
         stream: Literal[False] = ...,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[ResponseModelBoundT],
         compaction_strategy: CompactionStrategy | None = None,
@@ -2558,7 +2558,7 @@ def run(
         *,
         stream: Literal[False] = ...,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[None] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -2574,7 +2574,7 @@ def run(
         *,
         stream: Literal[True],
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[Any] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -2589,7 +2589,7 @@ def run(
         *,
         stream: bool = False,
         session: AgentSession | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         options: ChatOptions[Any] | None = None,
         compaction_strategy: CompactionStrategy | None = None,
diff --git a/python/packages/core/pyproject.toml b/python/packages/core/pyproject.toml
index d3b28c529d6..0b8e00c0602 100644
--- a/python/packages/core/pyproject.toml
+++ b/python/packages/core/pyproject.toml
@@ -31,11 +31,6 @@ dependencies = [
 ]
 
 [project.optional-dependencies]
-# Deliberately NOT part of `all`: the agent-hooks enforcement middleware is an
-# explicitly opt-in experimental feature.
-agent-hooks = [
-    "agent-hooks-sdk>=0.1.0a4,<0.2",
-]
 all = [
     "mcp>=1.24.0,<2",
     "agent-framework-a2a",
diff --git a/python/packages/core/tests/core/test_agent_hooks.py b/python/packages/core/tests/core/test_agent_hooks.py
index ef6a7b3ed20..4d5815ac544 100644
--- a/python/packages/core/tests/core/test_agent_hooks.py
+++ b/python/packages/core/tests/core/test_agent_hooks.py
@@ -191,15 +191,12 @@ async def test_from_emitter_factory_requires_both_arguments() -> None:
 
 
 @requires_sdk
-async def test_bare_bundle_at_construction_is_fully_enforced(chat_client_base: MockBaseChatClient) -> None:
-    # Passing the bundle bare (instead of inside a list) at construction must install
-    # it exactly like `middleware=[bundle]` — previously it was silently dropped and
-    # the run executed fully unhooked.
+async def test_bundle_at_construction_is_fully_enforced(chat_client_base: MockBaseChatClient) -> None:
     records: list[InterceptionRecord] = []
     guard = PointGuard("output", Verdict.deny(reason="egress_blocked"))
     agent = Agent(
         client=chat_client_base,
-        middleware=create_agent_hooks_middleware([guard], record_sink=records.append),
+        middleware=[create_agent_hooks_middleware([guard], record_sink=records.append)],
     )
 
     with pytest.raises(InterceptionBlocked) as exc_info:
@@ -2736,16 +2733,16 @@ def test_agent_hooks_middleware_importable_without_sdk(monkeypatch: pytest.Monke
         is agent_hooks_module.create_agent_hooks_middleware_from_emitter
     )
 
-    with pytest.raises(ModuleNotFoundError, match=r"agent-framework-core\[agent-hooks\]"):
+    with pytest.raises(ModuleNotFoundError, match="pip install agent-hooks-sdk"):
         agent_framework.create_agent_hooks_middleware([cast("Any", object())])
-    with pytest.raises(ModuleNotFoundError, match=r"agent-framework-core\[agent-hooks\]"):
+    with pytest.raises(ModuleNotFoundError, match="pip install agent-hooks-sdk"):
         agent_framework.create_agent_hooks_middleware_from_emitter(cast("Any", object()), cast("Any", object()))
 
 
-def test_broken_sdk_installation_is_not_masked_as_missing_extra(monkeypatch: pytest.MonkeyPatch) -> None:
+def test_broken_sdk_installation_is_not_masked_as_missing_sdk(monkeypatch: pytest.MonkeyPatch) -> None:
     # A transitively missing dependency (or any other breakage inside the SDK) must
-    # propagate unchanged — only a genuinely absent `agent_hooks` package gets the
-    # install-the-extra hint.
+    # propagate unchanged; only a genuinely absent `agent_hooks` package gets the
+    # SDK installation hint.
     _hide_agent_hooks(
         monkeypatch, error=ModuleNotFoundError("No module named 'some_native_dep'", name="some_native_dep")
     )
diff --git a/python/packages/core/tests/core/test_harness_agent.py b/python/packages/core/tests/core/test_harness_agent.py
index 04f6488e7cf..6535a6fc68f 100644
--- a/python/packages/core/tests/core/test_harness_agent.py
+++ b/python/packages/core/tests/core/test_harness_agent.py
@@ -6,7 +6,7 @@
 import warnings
 from collections.abc import AsyncIterable, Awaitable, Mapping, Sequence
 from pathlib import Path
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, cast
 from unittest.mock import patch
 
 import pytest
@@ -1132,6 +1132,25 @@ async def process(self, context: Any, call_next: Any) -> None:
     assert [type(mw) for mw in agent.middleware] == [MessageInjectionMiddleware, _CustomMiddleware]
 
 
+def test_create_harness_agent_rejects_generator_middleware() -> None:
+    """Harness middleware rejects iterables that are not sequences."""
+    from agent_framework import AgentMiddleware
+
+    class _CustomMiddleware(AgentMiddleware):
+        async def process(self, context: Any, call_next: Any) -> None:
+            await call_next()
+
+    middleware = (item for item in [_CustomMiddleware()])
+
+    with pytest.raises(TypeError):
+        create_harness_agent(
+            client=_FakeChatClient(),  # type: ignore[arg-type]
+            max_context_window_tokens=128_000,
+            max_output_tokens=16_384,
+            middleware=cast("Any", middleware),
+        )
+
+
 def test_create_harness_agent_no_middleware_when_tool_approval_disabled_and_none() -> None:
     """Only the always-on message injection middleware remains when tool approval is disabled."""
     from agent_framework import MessageInjectionMiddleware
diff --git a/python/packages/core/tests/core/test_middleware_with_agent.py b/python/packages/core/tests/core/test_middleware_with_agent.py
index ee2ba7b204d..3fcfe49400a 100644
--- a/python/packages/core/tests/core/test_middleware_with_agent.py
+++ b/python/packages/core/tests/core/test_middleware_with_agent.py
@@ -2,7 +2,7 @@
 
 import asyncio
 import threading
-from collections.abc import Awaitable, Callable
+from collections.abc import Awaitable, Callable, Iterator
 from typing import Any, cast
 
 import pytest
@@ -38,6 +38,14 @@
 # region Agent Tests
 
 
+class _IterableAgentMiddleware(AgentMiddleware):
+    def __iter__(self) -> Iterator[Any]:
+        return iter(())
+
+    async def process(self, context: AgentContext, call_next: Callable[[], Awaitable[None]]) -> None:
+        await call_next()
+
+
 class TestChatAgentClassBasedMiddleware:
     """Test cases for class-based middleware integration with Agent."""
 
@@ -72,50 +80,32 @@ async def process(self, context: AgentContext, call_next: Callable[[], Awaitable
         # Verify middleware execution order
         assert execution_order == ["agent_middleware_before", "agent_middleware_after"]
 
-    async def test_bare_middleware_at_construction_is_installed(self, client: SupportsChatGetResponse) -> None:
-        """A single middleware object passed bare (not in a list) at construction is installed.
-
-        Construction-time middleware mirrors categorize_middleware's single-source
-        handling, matching the run-level ``middleware=`` behavior instead of silently
-        dropping the middleware.
-        """
-        execution_order: list[str] = []
-
-        class TrackingAgentMiddleware(AgentMiddleware):
-            async def process(self, context: AgentContext, call_next: Callable[[], Awaitable[None]]) -> None:
-                execution_order.append("before")
-                await call_next()
-                execution_order.append("after")
-
-        agent = Agent(client=client, middleware=TrackingAgentMiddleware())
-
-        response = await agent.run([Message(role="user", contents=["test message"])])
-
-        assert response is not None
-        assert execution_order == ["before", "after"]
-
-    async def test_bare_middleware_assigned_to_attribute_is_installed(self, client: SupportsChatGetResponse) -> None:
-        """A single middleware object assigned bare to ``agent.middleware`` executes.
+    @pytest.mark.parametrize("middleware", [_IterableAgentMiddleware(), "middleware", b"middleware"])
+    def test_non_sequence_middleware_at_construction_is_rejected(
+        self, client: SupportsChatGetResponse, middleware: object
+    ) -> None:
+        """Construction rejects iterable middleware objects and string sequences."""
+        with pytest.raises(TypeError):
+            Agent(client=client, middleware=cast("Any", middleware))
 
-        categorize_middleware owns the bare-source rule (a non-sequence source is a
-        one-element list) and ``run()`` passes the raw attribute straight to it, so a
-        bare attribute assignment — which used to be silently ignored — now executes.
-        """
-        execution_order: list[str] = []
+    async def test_iterable_middleware_assigned_to_attribute_is_rejected(self, client: SupportsChatGetResponse) -> None:
+        """An iterable middleware object assigned to ``agent.middleware`` is rejected."""
+        agent = Agent(client=client)
+        agent.middleware = cast("Any", _IterableAgentMiddleware())
 
-        class TrackingAgentMiddleware(AgentMiddleware):
-            async def process(self, context: AgentContext, call_next: Callable[[], Awaitable[None]]) -> None:
-                execution_order.append("before")
-                await call_next()
-                execution_order.append("after")
+        with pytest.raises(TypeError):
+            await agent.run([Message(role="user", contents=["test message"])])
 
+    async def test_generator_run_middleware_is_rejected(self, client: SupportsChatGetResponse) -> None:
+        """Per-run middleware rejects iterables that are not sequences."""
         agent = Agent(client=client)
-        agent.middleware = cast("Any", TrackingAgentMiddleware())
+        middleware = (item for item in [_IterableAgentMiddleware()])
 
-        response = await agent.run([Message(role="user", contents=["test message"])])
-
-        assert response is not None
-        assert execution_order == ["before", "after"]
+        with pytest.raises(TypeError):
+            await agent.run(
+                [Message(role="user", contents=["test message"])],
+                middleware=cast("Any", middleware),
+            )
 
     async def test_class_based_function_middleware_with_chat_agent(self, client: "MockChatClient") -> None:
         """Test class-based function middleware with Agent."""
diff --git a/python/packages/foundry/agent_framework_foundry/_agent.py b/python/packages/foundry/agent_framework_foundry/_agent.py
index 862c54a2a99..0407f9c48fa 100644
--- a/python/packages/foundry/agent_framework_foundry/_agent.py
+++ b/python/packages/foundry/agent_framework_foundry/_agent.py
@@ -299,7 +299,7 @@ def as_agent(
         tools: ToolTypes | Callable[..., Any] | Sequence[ToolTypes | Callable[..., Any]] | None = None,
         default_options: FoundryAgentOptionsT | Mapping[str, Any] | None = None,
         context_providers: Sequence[ContextProvider] | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         require_per_service_call_history_persistence: bool = False,
         function_invocation_configuration: FunctionInvocationConfiguration | None = None,
         compaction_strategy: CompactionStrategy | None = None,
@@ -671,7 +671,7 @@ def __init__(
         default_headers: Mapping[str, str] | None = None,
         tools: FunctionTool | Callable[..., Any] | Sequence[FunctionTool | Callable[..., Any]] | None = None,
         context_providers: Sequence[ContextProvider] | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         client_type: type[RawFoundryAgentChatClient] | None = None,
         env_file_path: str | None = None,
         env_file_encoding: str | None = None,
@@ -961,7 +961,7 @@ def __init__(
         default_headers: Mapping[str, str] | None = None,
         tools: FunctionTool | Callable[..., Any] | Sequence[FunctionTool | Callable[..., Any]] | None = None,
         context_providers: Sequence[ContextProvider] | None = None,
-        middleware: MiddlewareTypes | Sequence[MiddlewareTypes] | None = None,
+        middleware: Sequence[MiddlewareTypes] | None = None,
         client_type: type[RawFoundryAgentChatClient] | None = None,
         env_file_path: str | None = None,
         env_file_encoding: str | None = None,
diff --git a/python/pyproject.toml b/python/pyproject.toml
index 144126b8613..11cb932d5d9 100644
--- a/python/pyproject.toml
+++ b/python/pyproject.toml
@@ -52,8 +52,7 @@ dev = [
 test = [
     "azure-monitor-opentelemetry",
     "mcp[ws]",
-    # Optional SDK behind core's `agent-hooks` extra; declared here (like mcp[ws]) so
-    # isolated source checks (dependency-pyright) can resolve its API.
+    # Optional SDK used by the agent-hooks tests and isolated source checks.
     "agent-hooks-sdk>=0.1.0a4,<0.2",
 ]
 
diff --git a/python/uv.lock b/python/uv.lock
index 5aa816032c6..c6e5a8ed284 100644
--- a/python/uv.lock
+++ b/python/uv.lock
@@ -439,9 +439,6 @@ dependencies = [
 ]
 
 [package.optional-dependencies]
-agent-hooks = [
-    { name = "agent-hooks-sdk" },
-]
 all = [
     { name = "agent-framework-a2a" },
     { name = "agent-framework-ag-ui" },
@@ -513,7 +510,6 @@ requires-dist = [
     { name = "agent-framework-purview", marker = "extra == 'all'", editable = "packages/purview" },
     { name = "agent-framework-redis", marker = "extra == 'all'", editable = "packages/redis" },
     { name = "agent-framework-tools", marker = "extra == 'all'", editable = "packages/tools" },
-    { name = "agent-hooks-sdk", marker = "extra == 'agent-hooks'", specifier = ">=0.1.0a4,<0.2" },
     { name = "mcp", marker = "extra == 'all'", specifier = ">=1.24.0,<2" },
     { name = "msgspec", specifier = ">=0.20.0,<0.22" },
     { name = "opentelemetry-api", specifier = ">=1.39.0,<2" },
@@ -521,7 +517,7 @@ requires-dist = [
     { name = "python-dotenv", specifier = ">=1,<2" },
     { name = "typing-extensions", specifier = ">=4.15.0,<5" },
 ]
-provides-extras = ["agent-hooks", "all"]
+provides-extras = ["all"]
 
 [package.metadata.requires-dev]
 dev = [{ name = "azure-ai-agentserver-core", specifier = ">=2.0.0b7,<3" }]