displayName
POST /api/v1/sessions/:sessionId/messages
method
POST
path
/api/v1/sessions/:sessionId/messages
responseShape
{ run: RunRecord, session: SessionSummary } | { error: 'not_found' }
authRequired
true
description
Send a new prompt into an existing session (optionally with attachments, agent override, model, approvalMode). Source: packages/agent-mux/gateway/src/server.ts:444-472.