Add configurable state reference to ChatMessageTrigger #3531

devin-ai-integration · 2026-01-06T19:26:49Z

Adds support for configurable chat history state in ChatMessageTrigger using a descriptor-based reference pattern. Users must now specify both output and state in the Config class. The state attribute specifies which state attribute to use for chat history via state = State.messages syntax.

Updates since last revision:

Fixed all runtime tests to use proper List[ArrayChatMessageContentItem] format for message parameter
Updated test assertions to check content with ArrayChatMessageContent instead of text
All tests now pass locally

Requested by: @vincent0426
Session: https://app.devin.ai/sessions/d067d7022ca8434189505a0fba0fe272

devin-ai-integration · 2026-01-06T19:26:54Z

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tests/workflows/chat_message_trigger_custom_state/workflows/custom_state_workflow.py

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src/vellum/workflows/triggers/chat_message.py

vincent0426 · 2026-01-07T05:25:47Z

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src/vellum/workflows/triggers/tests/test_chat_message.py

vincent0426 · 2026-01-07T05:31:41Z

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chatgpt-codex-connector · 2026-01-07T05:41:05Z

Codex Review: Didn't find any major issues. Swish!

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- Add chat_history_key field to ChatMessageTrigger.Config with default 'chat_history' - Update __on_workflow_initiated__ and __on_workflow_fulfilled__ to use configurable key - Update TypeScript types and codegen to support chatHistoryKey in exec_config - Update serialization to include chat_history_key when it differs from default - Add tests for custom chat_history_key functionality Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

- Change chat_history_key: str to state: StateValueReference[List[ChatMessage]] - Update serialization to use state_variable_id format - Update codegen to generate state = State.something syntax - Update tests and snapshots for new API Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

… attribute Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

…licate type Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 · 2026-01-08T01:32:08Z

...ee/workflows/display/tests/workflow_serialization/test_chat_message_trigger_serialization.py

+    # AND the error should be a TriggerValidationError with the expected message
+    error = state_errors[0]
+    assert isinstance(error, TriggerValidationError)
+    assert "Chat Trigger state must be specified" in str(error)


test when state is not specified

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 · 2026-01-08T01:47:17Z

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chatgpt-codex-connector · 2026-01-08T01:57:41Z

ee/vellum_ee/workflows/display/workflows/base_workflow_display.py

+        if state is None:
+            self.display_context.add_validation_error(
+                TriggerValidationError(
+                    message="Chat Trigger state must be specified.",
+                    trigger_class_name=trigger_class.__name__,
+                )
+            )
+
+        if output is None or state is None:
            return None


Preserve default chat_history when Config.state is unset

This serializer now treats Config.state as mandatory and returns None for the entire exec_config when it’s missing. That’s inconsistent with the runtime behavior in ChatMessageTrigger, which still falls back to state.chat_history when Config.state is None. As a result, workflows that rely on the default chat history (no explicit state set, but chat_history present on the workflow state) will suddenly serialize with missing exec_config/state and be flagged as invalid, even though they still execute. Consider defaulting to the workflow’s chat_history state variable during serialization (or at least emitting the default exec_config) so serialization matches runtime behavior.

Useful? React with 👍 / 👎.

DevinAI can we default to chat_history

Done! Updated the serialization to default to "chat_history" when Config.state is not specified. The serializer now looks for a state value with name "chat_history" in the workflow's state class and uses that if found. Updated the test to verify this default behavior works correctly.

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 · 2026-01-08T02:05:21Z

ee/vellum_ee/workflows/display/workflows/base_workflow_display.py

+                    break
+
+        if state is None:
+            return None


DevinAI should we still raise error here if its none?

Yes, added a validation error when state is still None after trying to default to "chat_history". The error message is: "Chat Trigger state must be specified or state class must have 'chat_history' attribute."

DevinAI make the error message only Chat Trigger state must be specified

Done! Simplified the error message to just "Chat Trigger state must be specified."

DevinAI can we just allow state to be none for backward compatibility? or will that break anything?

Yes, we can allow state to be None for backward compatibility. It won't break anything - the serialization will just return None for exec_config, and the runtime already handles this gracefully by returning early without appending to chat history.

Should I remove the validation error so that state can be None without raising an error?

DevinAI yes

Done! Removed the validation error so state can be None for backward compatibility. When state is None (and no "chat_history" exists), the exec_config will still include the output but won't include the state field.

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 · 2026-01-08T02:08:23Z

ee/vellum_ee/workflows/display/workflows/base_workflow_display.py

+                    break
+
+        if state is None:
+            return None


DevinAI make the error message only Chat Trigger state must be specified

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 · 2026-01-08T02:10:15Z

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chatgpt-codex-connector · 2026-01-08T02:13:55Z

ee/vellum_ee/workflows/display/workflows/base_workflow_display.py

+        # If state is not specified, default to "chat_history" state value
+        if state is None:
+            for state_value in self.display_context.global_state_value_displays:
+                if state_value.name == "chat_history":
+                    state = state_value


Default to local chat_history state before global

The defaulting logic iterates global_state_value_displays and picks the first state named chat_history. In nested workflows, that dict is built by copying the parent’s state values and then adding the child’s, so a parent chat_history will be chosen first. This means a ChatMessageTrigger in a nested workflow that omits Config.state will serialize its exec_config to the parent state_variable_id even though runtime defaults to the nested workflow’s state, causing a mismatch in serialized workflow displays and state tracking. This only occurs when both parent and child define chat_history and Config.state is omitted, but in that case it should prefer the local state_value_displays or explicitly prioritize the current workflow’s state class.

Useful? React with 👍 / 👎.

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

devin-ai-integration bot assigned vincent0426 Jan 6, 2026

devin-ai-integration bot requested a review from vincent0426 January 6, 2026 19:26

devin-ai-integration bot changed the title ~~Add configurable chat_history_key to ChatMessageTrigger~~ Add configurable state reference to ChatMessageTrigger Jan 6, 2026

devin-ai-integration bot force-pushed the devin/1767727073-chat-history-key-config branch 2 times, most recently from bc2b18d to b31409a Compare January 7, 2026 03:14

vincent0426 reviewed Jan 7, 2026

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vincent0426 marked this pull request as ready for review January 7, 2026 05:09

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src/vellum/workflows/triggers/chat_message.py Show resolved Hide resolved

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src/vellum/workflows/triggers/tests/test_chat_message.py Outdated Show resolved Hide resolved

devin-ai-integration bot and others added 16 commits January 8, 2026 01:05

Fix codegen: use camelCase stateVariableId and skip inherited message…

0abd5cd

… attribute Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Fix mypy error: use direct type narrowing for state variable

624f294

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Fix prettier formatting in chat-message-trigger.ts

18318dc

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Rename _get_chat_history_key to get_state_key

a5718a8

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Rename get_state_key to _get_state_key (private method)

27f1a0e

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Refactor: reuse WorkflowStateVariableWorkflowReference instead of dup…

4735fe4

…licate type Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Regenerate entire snapshot file

e942689

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Update snapshot after rebase

22615fc

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Move custom state tests to e2e test under tests/workflows

c857e73

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Use string-based LazyReference instead of lambda

5e42b37

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Move custom state serialization test to workflow_serialization directory

695bacd

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Update test to assert full trigger structure directly

8d92bb8

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Add assertion to verify state_variable_id matches state_variables

5de5ff9

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Use StateValueReference.resolve() for proper parent state walking

181a14a

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Update test to use _resolve_state() instead of removed _get_state_key()

47b38e2

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

devin-ai-integration bot force-pushed the devin/1767727073-chat-history-key-config branch from 3bf419e to 47b38e2 Compare January 8, 2026 01:14

devin-ai-integration bot and others added 4 commits January 8, 2026 01:22

Fix: return None when output is None regardless of state

ca13c0f

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Add validation error when state is not specified and add test

251dd00

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Update test to use full assertion format for triggers

17104b7

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Keep original output validation test, add separate state validation test

afed886

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 reviewed Jan 8, 2026

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devin-ai-integration bot and others added 2 commits January 8, 2026 01:33

Fix test: update expected attribute type from JSON to ARRAY

165dc83

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Fix tests: use list format for message parameter and update assertions

a219b8d

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

chatgpt-codex-connector bot reviewed Jan 8, 2026

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Default to chat_history state when Config.state is not specified

b06cf53

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 reviewed Jan 8, 2026

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Add validation error when state is None and no chat_history exists

7766383

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

vincent0426 approved these changes Jan 8, 2026

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Simplify error message to 'Chat Trigger state must be specified'

d4583bb

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

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Allow state to be None for backward compatibility

66c6937

Co-Authored-By: vincent@vellum.ai <0426vincent@gmail.com>

Add configurable state reference to ChatMessageTrigger #3531

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