From 65e489059a34d8a2ff9497f1a913dd5dd2df5b58 Mon Sep 17 00:00:00 2001 From: Chiranjeet Mishra Date: Wed, 14 Oct 2026 03:45:48 +0000 Subject: [PATCH] docs: handoff carries only the destination's first system message On handoff the destination's system prompt is its first system message; additional system messages in model.messages are dropped. --- fern/squads/handoff/context-and-variables.mdx | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fern/squads/handoff/context-and-variables.mdx b/fern/squads/handoff/context-and-variables.mdx index 5fdf696d6..4536719b4 100644 --- a/fern/squads/handoff/context-and-variables.mdx +++ b/fern/squads/handoff/context-and-variables.mdx @@ -9,6 +9,10 @@ A handoff carries **conversation messages** and **variable values** separately. Values already collected in the call remain available to later assistants even if the destination receives no earlier messages. + + The destination's system prompt is the first `system` message in its `model.messages`. On a handoff, any additional `system` messages in that array are dropped, so combine all destination instructions into a single system message. + + ## Context engineering Set `contextEngineeringPlan` on an assistant or squad destination. It filters the messages sent to that destination; it does not clear saved variables.