fix: dedupe silent reply prompt guidance

docs/channels/groups.md

@@ -289,6 +289,7 @@ Replying to a bot message counts as an implicit mention when the channel support
     - Surfaces that provide explicit mentions still pass; patterns are a fallback.
     - Per-agent override: `agents.list[].groupChat.mentionPatterns` (useful when multiple agents share a group).
     - Mention gating is only enforced when mention detection is possible (native mentions or `mentionPatterns` are configured).
+    - Group chat prompt context carries the resolved silent-reply instruction every turn; workspace files should not duplicate `NO_REPLY` mechanics.
     - Groups where silent replies are allowed treat clean empty or reasoning-only model turns as silent, equivalent to `NO_REPLY`. Direct chats still treat empty replies as a failed agent turn.
     - Discord defaults live in `channels.discord.guilds."*"` (overridable per guild/channel).
     - Group history context is wrapped uniformly across channels and is **pending-only** (messages skipped due to mention gating); use `messages.groupChat.historyLimit` for the global default and `channels.<channel>.historyLimit` (or `channels.<channel>.accounts.*.historyLimit`) for overrides. Set `0` to disable.

docs/concepts/system-prompt.md

@@ -96,6 +96,11 @@ OpenClaw can render smaller system prompts for sub-agents. The runtime sets a
 When `promptMode=minimal`, extra injected prompts are labeled **Subagent
 Context** instead of **Group Chat Context**.
 
+For channel auto-reply runs, OpenClaw can omit the generic **Silent Replies**
+section when the direct/group chat context already includes the resolved
+conversation-specific `NO_REPLY` behavior. This avoids repeating token mechanics
+in both the global system prompt and channel context.
+
 ## Workspace bootstrap injection
 
 Bootstrap files are trimmed and appended under **Project Context** so the model sees identity and profile context without needing explicit reads:

docs/reference/templates/AGENTS.md

@@ -94,7 +94,7 @@ In group chats where you receive every message, be **smart about when to contrib
 - Correcting important misinformation
 - Summarizing when asked
 
-**Stay silent (HEARTBEAT_OK) when:**
+**Stay silent when:**
 
 - It's just casual banter between humans
 - Someone already answered the question