Native "Send reply" action in workflow builder for Support conversations

Feature request

The workflow automation docs cover ticket management actions (status changes, SLA, assignment) but there's no native action for posting a reply into a conversation. This is a critical missing piece for AI-assisted support workflows.

Use case:

1. Trigger on $conversation_message_received
2. Call an external LLM via webhook to generate a draft reply
3. Post that reply back into the conversation

Step 3 currently has no supported path – the /compose/ endpoint blocks external API access (see related bug report), and there's no native workflow action for sending replies.

Proposed solution:

Add a native "Send reply" action under the Support section in the workflow builder, which accepts:

content – the message body (supports output variable references like {variables.draft_reply})
conversation – the ticket ID (can be pulled from {event.properties.ticket_id})
Optionally:

is_private – boolean to post as an internal note vs. customer-visible reply
Why this matters:

This closes the loop for AI-assisted support workflows entirely within PostHog, without requiring external API access or workarounds. The trigger, LLM call, and reply can all be orchestrated natively.

Debug info

N/A

Start with the workflow automation docs and the existing /compose/ endpoint behavior described in the issue. Trace how a conversation message trigger, webhook output variable, and ticket ID are represented, then define completion as a Support workflow action that posts content to the selected conversation with the optional private-note setting.