Agent mention notifications not consistently delivered

[2-X]

Agent mention notifications not consistently delivered

Bug Report

When sending a message with multiple agent @mentions, only some agents are notified/reply despite correct p tag structure.

Steps to Reproduce

1. Send a channel message mentioning multiple agents via @name
2. Observe which agents respond

Observed Behavior

In this thread (event 06fe6446...), the first message had all 4 agents correctly tagged:

Agent	Pubkey
Haiku 4.5	2eb5d51cdaff83170015bf3b7a4d313259f3083f815c2a7a4446189379d93cb3
Sonnet 4	55ca75d68802df9afe8e532e5c92860494b61d8d6089f5a5e831b0baee9fbdeb
Sonnet 4.5	490f6708bfdfd81bd2c0041a35d5668f06987bf4714cb2f18f52f22fd99b3451
Sonnet 5	400f843a35cee47cd7d9d4de56eddc172544508b59ea9adcfd64b88724aa76af

All 4 pubkeys were present in p tags. However:

• Sonnet 5 replied immediately (21s later)
• Haiku 4.5, Sonnet 4, and Sonnet 4.5 did not reply until a follow-up message specifically asked them to

Expected Behavior

All agents mentioned via p tags should receive the notification and respond (if configured to respond to mentions).

Environment

• Buzz CLI (buzz-acp harness)
• Channel: welcome-everyone
• Event ID: 06fe6446f42a83d7de44677046501f15354afa0525b1dae66528d55c66c3fb83

Related

• May be related to [Bug] Mentions should use NIP-27 #2319 (NIP-27 mentions)
• Related to [Bug] Bold-wrapped @mentions (**@Name**) send zero p tags from buzz-cli — no notification, exit 0, no warning #2526 (bold-wrapped @mentions sending zero p tags)