InputMessageNode HITL state not propagated to calling agent in multi-agent orchestration

[groganz]

Summary

When a WayFlow flow containing an InputMessageNode is called as a child agent by an orchestrator via the A2A protocol, the input-required state produced by the InputMessageNode is never surfaced to the calling orchestrator. The orchestrator's send_message always returns completed (or failed), bypassing the HITL gate entirely.

Expected behaviour (per A2A spec)

The A2A specification defines input-required as a first-class task state. An orchestrator calling a child agent via send_message should receive input-required when the child hits an InputMessageNode, allowing the orchestrator to surface the HITL to the end user before resuming the child with the collected input.

Actual behaviour

In wayflowcore/agentserver/a2a/_worker.py, when a task starts (needs_new_conv = True) and the flow contains an InputMessageStep, the worker:

1. Pre-executes the conversation to reach the InputMessageStep (flow pauses internally)
2. Immediately appends the caller's incoming message to the conversation
3. Executes again — the InputMessageStep consumes the caller's message as its input
4. The flow continues past the gate and eventually returns completed

The input-required state exists only transiently in memory between steps 1 and 2. It is never persisted or returned to the calling agent; the HTTP response only arrives after full execution.

Minimal reproduction

Orchestrator (WayFlow flow with AgentNode)
  └─▶ Child Agent (WayFlow flow: StartNode → OutputMessageNode → InputMessageNode → ApiNode → EndNode)

1. Orchestrator calls child via AgentNode / A2A send_message
2. Child flow pre-executes to InputMessageNode → internally input-required
3. Caller's resume message (e.g. "Approved") is appended and immediately consumed by the InputMessageNode
4. ApiNode executes with "Approved" as the collected input — not the actual user response
5. Child returns completed; orchestrator never sees input-required

Impact

Multi-agent workflows that rely on InputMessageNode for scoped human-in-the-loop data collection (e.g. asking the user to confirm a parameter before a long-running step) cannot function when the flow is invoked as a child agent. The gate is silently bypassed, and the caller's generic resume acknowledgment is used as the HITL input.

Suggested fix

When needs_new_conv = True and the flow contains an InputMessageStep, _worker.py should:

• Pre-execute to the InputMessageStep
• Persist the input-required state
• Return the input-required response to the caller without processing the incoming message
• Only on the next send_message call (when needs_new_conv = False and the conversation is in UserMessageRequestStatus) should the incoming message be forwarded to the InputMessageStep

This aligns with the prioritize_task / needs_new_conv = False path that already handles subsequent messages correctly.

Environment

• wayflowcore 26.1.x
• A2A blocking mode
• Multi-agent orchestration (parent Flow with AgentNode calling a child Flow containing InputMessageNode)

[groganz]

Cross-linking the spec-level companion at oracle/agent-spec#183. The runtime fix proposed in this issue is concrete and needed, but the spec is silent on what FlowNode is contractually expected to do when its child returns input-required. Without normative language, different adapters will diverge on parent-propagation semantics — even if wayflowcore lands the fix here, OAS files won't have portable HITL-propagation behavior across other runtimes.

The spec-level issue is filed to push for that normative contract so wayflowcore's fix becomes the canonical behavior rather than implementation-defined.