Python: Include reasoning messages in MESSAGES_SNAPSHOT events (#4844)

* Include reasoning messages in MESSAGES_SNAPSHOT (#4843)

FlowState now tracks reasoning messages emitted during a run.
_emit_text_reasoning() persists reasoning (including encrypted_value)
into flow.reasoning_messages, and _build_messages_snapshot() appends
them to the final MESSAGES_SNAPSHOT event.

Changes:
- Add reasoning_messages field to FlowState
- Update _emit_text_reasoning() to accept optional flow parameter
- Include reasoning_messages in _build_messages_snapshot()
- Add 'reasoning' to ALLOWED_AGUI_ROLES so normalize_agui_role()
  preserves the role through snapshot round-trips
- Skip reasoning messages in agui_messages_to_agent_framework() since
  they are UI-only state and should not be forwarded to LLM providers
- Add regression tests for snapshot emission, encrypted value
  preservation, and multi-turn round-trip with reasoning

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

* Python: Include reasoning messages in MESSAGES_SNAPSHOT events

Fixes #4843

* Fix PR review feedback for reasoning persistence (#4843)

- Accumulate reasoning text per message_id (append deltas) instead of
  storing only the current chunk, matching flow.accumulated_text pattern
- Use camelCase encryptedValue in snapshot JSON to match AG-UI protocol
  conventions (toolCallId, encryptedValue)
- Normalize snake_case encrypted_value to encryptedValue in
  agui_messages_to_snapshot_format for input compatibility
- Update normalize_agui_role docstring to include reasoning role
- Add tests for incremental reasoning accumulation and key normalization

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

* Address review feedback for #4843: Python: agent-framework-ag-ui: include reasoning messages in MESSAGES_SNAPSHOT

---------

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

python/packages/ag-ui/tests/ag_ui/test_message_adapters.py

@@ -1669,3 +1669,94 @@ def test_agui_fresh_approval_is_still_processed():
     assert len(approval_contents) == 1, "Fresh approval should produce function_approval_response"
     assert approval_contents[0].approved is True
     assert approval_contents[0].function_call.name == "get_datetime"
+
+
+class TestReasoningRoundTrip:
+    """Tests for reasoning message handling in inbound/outbound adapters."""
+
+    def test_reasoning_skipped_on_inbound(self):
+        """Reasoning messages from prior snapshot are not forwarded to the LLM."""
+        messages_input = [
+            {"id": "u1", "role": "user", "content": "Hello"},
+            {"id": "r1", "role": "reasoning", "content": "Thinking..."},
+            {"id": "a1", "role": "assistant", "content": "Hi there"},
+        ]
+
+        result = agui_messages_to_agent_framework(messages_input)
+
+        roles = [m.role if hasattr(m.role, "value") else str(m.role) for m in result]
+        assert "reasoning" not in roles
+        assert len(result) == 2
+
+    def test_reasoning_preserved_in_snapshot_format(self):
+        """Reasoning messages retain their role through snapshot normalization."""
+        messages_input = [
+            {"id": "u1", "role": "user", "content": "Hello"},
+            {"id": "r1", "role": "reasoning", "content": "Thinking about this..."},
+            {"id": "a1", "role": "assistant", "content": "Answer"},
+        ]
+
+        result = agui_messages_to_snapshot_format(messages_input)
+
+        reasoning_msgs = [m for m in result if m.get("role") == "reasoning"]
+        assert len(reasoning_msgs) == 1
+        assert reasoning_msgs[0]["content"] == "Thinking about this..."
+
+    def test_reasoning_with_encrypted_value_in_snapshot_format(self):
+        """Reasoning with encryptedValue passes through snapshot normalization."""
+        messages_input = [
+            {
+                "id": "r1",
+                "role": "reasoning",
+                "content": "visible",
+                "encryptedValue": "secret-data",
+            },
+        ]
+
+        result = agui_messages_to_snapshot_format(messages_input)
+
+        assert len(result) == 1
+        assert result[0]["role"] == "reasoning"
+        assert result[0]["encryptedValue"] == "secret-data"
+
+    def test_reasoning_encrypted_value_snake_case_normalized(self):
+        """Snake-case encrypted_value is normalized to encryptedValue in snapshot format."""
+        messages_input = [
+            {
+                "id": "r1",
+                "role": "reasoning",
+                "content": "visible",
+                "encrypted_value": "snake-case-data",
+            },
+        ]
+
+        result = agui_messages_to_snapshot_format(messages_input)
+
+        assert len(result) == 1
+        assert result[0]["encryptedValue"] == "snake-case-data"
+        assert "encrypted_value" not in result[0]
+
+    def test_multi_turn_with_reasoning_in_prior_snapshot(self):
+        """Second turn with reasoning from prior snapshot does not corrupt messages."""
+        messages_input = [
+            {"id": "u1", "role": "user", "content": "First question"},
+            {"id": "r1", "role": "reasoning", "content": "Prior reasoning"},
+            {"id": "a1", "role": "assistant", "content": "First answer"},
+            {"id": "u2", "role": "user", "content": "Follow-up question"},
+        ]
+
+        result = agui_messages_to_agent_framework(messages_input)
+
+        roles = [m.role if hasattr(m.role, "value") else str(m.role) for m in result]
+        # Reasoning is filtered out, other messages preserved in order
+        assert roles == ["user", "assistant", "user"]
+        # Content not corrupted
+        texts = []
+        for m in result:
+            for c in m.contents or []:
+                if hasattr(c, "text") and c.text:
+                    texts.append(c.text)
+        assert "First question" in texts
+        assert "First answer" in texts
+        assert "Follow-up question" in texts
+        assert "Prior reasoning" not in texts

python/packages/ag-ui/tests/ag_ui/test_run.py

@@ -1346,3 +1346,158 @@ class TestEmitContentMcpRouting:
 
         assert len(events) == 5
         assert isinstance(events[0], ReasoningStartEvent)
+
+
+class TestReasoningInSnapshot:
+    """Tests for reasoning message inclusion in MESSAGES_SNAPSHOT."""
+
+    def test_reasoning_persisted_to_flow_state(self):
+        """_emit_text_reasoning with flow persists reasoning into flow.reasoning_messages."""
+        flow = FlowState()
+        content = Content.from_text_reasoning(
+            id="reason_persist",
+            text="Let me think step by step.",
+        )
+
+        _emit_text_reasoning(content, flow)
+
+        assert len(flow.reasoning_messages) == 1
+        assert flow.reasoning_messages[0]["id"] == "reason_persist"
+        assert flow.reasoning_messages[0]["role"] == "reasoning"
+        assert flow.reasoning_messages[0]["content"] == "Let me think step by step."
+        assert "encryptedValue" not in flow.reasoning_messages[0]
+
+    def test_reasoning_with_encrypted_value_persisted(self):
+        """Reasoning with protected_data preserves encryptedValue in flow state."""
+        flow = FlowState()
+        content = Content.from_text_reasoning(
+            id="reason_enc",
+            text="visible reasoning",
+            protected_data="encrypted-data-123",
+        )
+
+        _emit_text_reasoning(content, flow)
+
+        assert len(flow.reasoning_messages) == 1
+        assert flow.reasoning_messages[0]["encryptedValue"] == "encrypted-data-123"
+
+    def test_snapshot_includes_reasoning(self):
+        """_build_messages_snapshot includes reasoning messages from flow state."""
+        from agent_framework_ag_ui._agent_run import _build_messages_snapshot
+
+        flow = FlowState()
+        flow.accumulated_text = "Here is my answer."
+        flow.reasoning_messages = [
+            {"id": "r1", "role": "reasoning", "content": "Thinking..."},
+        ]
+
+        snapshot = _build_messages_snapshot(flow, [])
+
+        roles = [m.get("role") if isinstance(m, dict) else getattr(m, "role", None) for m in snapshot.messages]
+        assert "reasoning" in roles
+
+    def test_snapshot_preserves_reasoning_encrypted_value(self):
+        """Snapshot reasoning with encryptedValue is preserved end-to-end."""
+        from agent_framework_ag_ui._agent_run import _build_messages_snapshot
+
+        flow = FlowState()
+        content = Content.from_text_reasoning(
+            id="reason_e2e",
+            text="visible",
+            protected_data="secret-data",
+        )
+        _emit_text_reasoning(content, flow)
+
+        text_content = Content.from_text("Final answer.")
+        _emit_text(text_content, flow)
+
+        snapshot = _build_messages_snapshot(flow, [])
+
+        reasoning_msgs = [
+            m
+            for m in snapshot.messages
+            if (m.get("role") if isinstance(m, dict) else getattr(m, "role", None)) == "reasoning"
+        ]
+        assert len(reasoning_msgs) == 1
+        msg = reasoning_msgs[0]
+        if isinstance(msg, dict):
+            assert msg["content"] == "visible"
+            assert msg["encryptedValue"] == "secret-data"
+
+    def test_emit_content_routes_reasoning_with_flow(self):
+        """_emit_content passes flow to _emit_text_reasoning for persistence."""
+        flow = FlowState()
+        content = Content.from_text_reasoning(text="routed reasoning")
+
+        _emit_content(content, flow)
+
+        assert len(flow.reasoning_messages) == 1
+        assert flow.reasoning_messages[0]["content"] == "routed reasoning"
+
+    def test_reasoning_without_flow_does_not_error(self):
+        """Calling _emit_text_reasoning without flow still works (backward compat)."""
+        content = Content.from_text_reasoning(text="no flow")
+
+        events = _emit_text_reasoning(content)
+
+        assert len(events) == 5
+        assert isinstance(events[0], ReasoningStartEvent)
+
+    def test_snapshot_reasoning_ordering(self):
+        """Reasoning messages appear after assistant text in snapshot."""
+        from agent_framework_ag_ui._agent_run import _build_messages_snapshot
+
+        flow = FlowState()
+        reasoning_content = Content.from_text_reasoning(id="r1", text="Thinking...")
+        _emit_text_reasoning(reasoning_content, flow)
+
+        text_content = Content.from_text("Answer")
+        _emit_text(text_content, flow)
+
+        snapshot = _build_messages_snapshot(flow, [{"id": "u1", "role": "user", "content": "Hi"}])
+
+        # user -> assistant text -> reasoning
+        assert len(snapshot.messages) == 3
+        roles = [m.get("role") if isinstance(m, dict) else getattr(m, "role", None) for m in snapshot.messages]
+        assert roles == ["user", "assistant", "reasoning"]
+
+    def test_reasoning_accumulates_incremental_deltas(self):
+        """Multiple reasoning deltas with the same id accumulate into one entry."""
+        flow = FlowState()
+        content1 = Content.from_text_reasoning(id="reason_inc", text="First ")
+        content2 = Content.from_text_reasoning(id="reason_inc", text="second ")
+        content3 = Content.from_text_reasoning(id="reason_inc", text="third.")
+
+        _emit_text_reasoning(content1, flow)
+        _emit_text_reasoning(content2, flow)
+        _emit_text_reasoning(content3, flow)
+
+        assert len(flow.reasoning_messages) == 1
+        assert flow.reasoning_messages[0]["id"] == "reason_inc"
+        assert flow.reasoning_messages[0]["content"] == "First second third."
+
+    def test_reasoning_accumulates_distinct_message_ids(self):
+        """Reasoning entries with different ids are stored separately."""
+        flow = FlowState()
+        content_a = Content.from_text_reasoning(id="a", text="alpha")
+        content_b = Content.from_text_reasoning(id="b", text="beta")
+
+        _emit_text_reasoning(content_a, flow)
+        _emit_text_reasoning(content_b, flow)
+
+        assert len(flow.reasoning_messages) == 2
+        assert flow.reasoning_messages[0]["content"] == "alpha"
+        assert flow.reasoning_messages[1]["content"] == "beta"
+
+    def test_reasoning_encrypted_value_updated_on_later_delta(self):
+        """encryptedValue is set even when it arrives with a later delta."""
+        flow = FlowState()
+        content1 = Content.from_text_reasoning(id="enc_late", text="part1 ")
+        content2 = Content.from_text_reasoning(id="enc_late", text="part2", protected_data="encrypted-payload")
+
+        _emit_text_reasoning(content1, flow)
+        _emit_text_reasoning(content2, flow)
+
+        assert len(flow.reasoning_messages) == 1
+        assert flow.reasoning_messages[0]["content"] == "part1 part2"
+        assert flow.reasoning_messages[0]["encryptedValue"] == "encrypted-payload"

python/packages/ag-ui/tests/ag_ui/test_utils.py

@@ -450,6 +450,7 @@ def test_normalize_agui_role_valid():
     assert normalize_agui_role("assistant") == "assistant"
     assert normalize_agui_role("system") == "system"
     assert normalize_agui_role("tool") == "tool"
+    assert normalize_agui_role("reasoning") == "reasoning"
 
 
 def test_normalize_agui_role_invalid():