Hosted declarative (#5530)

* Fix declarative Workflow.as_agent() by accepting list[Message] in start executor

The declarative start executor (JoinExecutor) only advertised dict and str
in its input_types, so WorkflowAgent.__init__ rejected it with
'Workflow's start executor cannot handle list[Message]'.

Add list[Message] to the JoinExecutor handler annotation and add a
matching branch in DeclarativeActionExecutor._ensure_state_initialized
that extracts the last user-message text and falls through to the
string-input initialization path, so =System.LastMessageText works
end-to-end via as_agent().

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Populate Conversation.messages from list[Message] trigger

When Workflow.as_agent() is invoked with a list[Message], the start executor now populates Conversation.messages / Conversation.history / System.conversations.{id}.messages with prior turns only (excluding the latest user message), and surfaces the latest user message via Inputs.input and System.LastMessage*. This matches InvokeAzureAgent's contract that the messages binding holds prior turns and the executor itself appends the new user input before invoking, avoiding double-append of the trailing user turn while preserving full history (incl. assistant/system/tool roles and multi-modal content) for downstream actions.

* Coerce Enum values when serializing PowerFx symbols

MessageRole and other str-subclass Enums passed isinstance(v, str) and were forwarded to pythonnet unchanged. pythonnet then raised 'MessageRole value cannot be converted to System.String' for every PowerFx primitive when ConditionGroup/Expr eval walked the symbol table containing Conversation.messages. Reduce Enum members to their underlying value before the primitive check so eval sees plain strings/ints.

* Foundry hosting: pass full conversation history to workflow agents

_handle_inner_workflow only forwarded the latest user turn to WorkflowAgent.run, even though _handle_inner_agent already prepends history fetched from Foundry storage to the messages it sends a regular agent. Declarative workflows reset Conversation.messages on every run (state.initialize), so checkpoint replay alone does not give them prior turns - the host has to pass them in, the same way it does for non-workflow agents. Mirror that contract: fetch context.get_history() and pass [*history, *input_messages] to the workflow agent.

---------

Co-authored-by: alliscode <bentho@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people

python/packages/declarative/agent_framework_declarative/_workflows/_declarative_base.py

@@ -29,6 +29,7 @@
 import logging
 import sys
 import uuid
+from enum import Enum
 from collections.abc import Mapping
 from dataclasses import dataclass
 from decimal import Decimal as _Decimal
@@ -121,7 +122,20 @@ def _make_powerfx_safe(value: Any) -> Any:
     Returns:
         A PowerFx-safe representation of the value
     """
-    if value is None or isinstance(value, _POWERFX_SAFE_TYPES):
+    if value is None:
+        return value
+
+    # Enum coercion must run BEFORE the primitive type check: many MAF
+    # enums (e.g. MessageRole) are ``str``-subclass enums, so they pass
+    # ``isinstance(v, str)`` but pythonnet refuses to convert them to
+    # ``System.String`` and raises ``'MessageRole' value cannot be
+    # converted to System.<X>'`` for every PowerFx primitive type. Reduce
+    # to the underlying value (or its string form) so PowerFx sees a
+    # plain ``str``/``int``.
+    if isinstance(value, Enum):
+        return _make_powerfx_safe(value.value)
+
+    if isinstance(value, _POWERFX_SAFE_TYPES):
         return value
 
     if isinstance(value, dict):

python/packages/foundry_hosting/agent_framework_foundry_hosting/_responses.py

@@ -256,6 +256,19 @@ async def _handle_inner_workflow(
         input_messages = _items_to_messages(input_items)
         is_streaming_request = request.stream is not None and request.stream is True
 
+        # Fetch prior conversation history from Foundry storage so workflow
+        # agents see the same history their non-workflow counterparts get
+        # (see _handle_inner_agent which builds messages from history +
+        # current input). Without this, declarative workflows triggered via
+        # WorkflowAgent.as_agent only ever see the latest user turn, even
+        # though the host's checkpoint replay restores the workflow's
+        # internal state - declarative workflows reset Conversation.messages
+        # on every new run, so cross-turn context has to come from the
+        # message list passed in, not from checkpointed workflow state.
+        history = await context.get_history()
+        history_messages = _output_items_to_messages(history)
+        full_messages = [*history_messages, *input_messages]
+
         _, are_options_set = _to_chat_options(request)
         if are_options_set:
             logger.warning("Workflow agent doesn't support runtime options. They will be ignored.")
@@ -307,7 +320,7 @@ async def _handle_inner_workflow(
 
         if not is_streaming_request:
             # Run the agent in non-streaming mode
-            response = await self._agent.run(input_messages, stream=False, checkpoint_storage=checkpoint_storage)
+            response = await self._agent.run(full_messages, stream=False, checkpoint_storage=checkpoint_storage)
 
             for message in response.messages:
                 for content in message.contents:
@@ -323,7 +336,7 @@ async def _handle_inner_workflow(
         tracker = _OutputItemTracker(response_event_stream)
 
         # Run the workflow agent in streaming mode
-        async for update in self._agent.run(input_messages, stream=True, checkpoint_storage=checkpoint_storage):
+        async for update in self._agent.run(full_messages, stream=True, checkpoint_storage=checkpoint_storage):
             for content in update.contents:
                 for event in tracker.handle(content):
                     yield event