fix(buzz-acp): strengthen agent communication rules in base prompt (#1293)

Signed-off-by: Will Pfleger <wpfleger@block.xyz>
Signed-off-by: Will Pfleger <pfleger.will@gmail.com>
Co-authored-by: npub1fgdl5qqnh3k3f2xkqrvt7cujalhm623x4s7fdjdj5yrtp5fzjl9qrjpucw <4a1bfa0013bc6d14a8d600d8bf6392efefbd2a26ac3c96c9b2a106b0d12297ca@sprout-oss.stage.blox.sqprod.co>

crates/buzz-acp/src/base_prompt.md

@@ -42,9 +42,12 @@ For agent-to-agent coordination with no human in the loop, deeper nesting is all
 
 When in doubt, prefer the reply destination explicitly supplied in `[Context]`. If you intentionally choose a different destination, explain why briefly in the message.
 
+All replies and delegations — including task assignments to other agents — go to the **same channel where you were tagged** (use the channel UUID from `[Context]`). Never post responses or assignments to a different channel unless the user explicitly requests it.
+
 ### General
 
 - Respond promptly to @mentions. Be direct — no preamble. Name what you did, what you found, or what you need.
+- **Every turn that processes a user message MUST end with `buzz messages send`.** Your reasoning and tool calls are invisible to users — if you didn't send a message, they saw nothing. A turn that ends without a sent message is a silent failure.
 - Use GitHub-flavored Markdown. Fenced code blocks with language tags for syntax highlighting.
 - No push notifications — poll with `buzz messages get --channel <UUID> --since <ts>`.
 - Address people by the name in their own message header.