diff --git a/plugin/index.ts b/plugin/index.ts
index 2dd9411..1de1e3a 100644
--- a/plugin/index.ts
+++ b/plugin/index.ts
@@ -24,6 +24,8 @@ type DebugConfig = {
 };
 
 const sessionDecision = new Map<string, DecisionRecord>();
+const sessionAllowed = new Map<string, boolean>(); // Track if session was allowed to speak (true) or forced no-reply (false)
+const sessionInjected = new Set<string>(); // Track which sessions have already injected the end marker
 const MAX_SESSION_DECISIONS = 2000;
 const DECISION_TTL_MS = 5 * 60 * 1000;
 function buildEndMarkerInstruction(endSymbols: string[], isGroupChat: boolean): string {
@@ -82,6 +84,7 @@ function extractUntrustedConversationInfo(text: string): Record<string, unknown>
 function deriveDecisionInputFromPrompt(
   prompt: string,
   messageProvider?: string,
+  channelIdFromCtx?: string,
 ): {
   channel: string;
   channelId?: string;
@@ -91,11 +94,17 @@ function deriveDecisionInputFromPrompt(
 } {
   const conv = extractUntrustedConversationInfo(prompt) || {};
   const channel = (messageProvider || "").toLowerCase();
-  const channelId =
-    (typeof conv.channel_id === "string" && conv.channel_id) ||
-    (typeof conv.chat_id === "string" && conv.chat_id.startsWith("channel:")
-      ? conv.chat_id.slice("channel:".length)
-      : undefined);
+
+  // Priority: ctx.channelId > conv.chat_id > conv.channel_id
+  let channelId = channelIdFromCtx;
+  if (!channelId) {
+    channelId =
+      (typeof conv.chat_id === "string" && conv.chat_id.startsWith("channel:")
+        ? conv.chat_id.slice("channel:".length)
+        : typeof conv.channel_id === "string" && conv.channel_id) ||
+      undefined;
+  }
+
   const senderId =
     (typeof conv.sender_id === "string" && conv.sender_id) ||
     (typeof conv.sender === "string" && conv.sender) ||
@@ -576,7 +585,7 @@ export default {
         );
       }
 
-      const derived = deriveDecisionInputFromPrompt(prompt, ctx.messageProvider);
+      const derived = deriveDecisionInputFromPrompt(prompt, ctx.messageProvider, ctx.channelId);
       // Only proceed if: discord channel AND prompt contains untrusted metadata
       const hasConvMarker = prompt.includes("Conversation info (untrusted metadata):");
       if (live.discordOnly !== false && (!hasConvMarker || derived.channel !== "discord")) return;
@@ -615,6 +624,8 @@ export default {
         if (accountId) {
           const turnCheck = checkTurn(derived.channelId, accountId);
           if (!turnCheck.allowed) {
+            // Forced no-reply - record this session as not allowed to speak
+            sessionAllowed.set(key, false);
             api.logger.info(
               `whispergate: turn gate blocked session=${key} accountId=${accountId} currentSpeaker=${turnCheck.currentSpeaker} reason=${turnCheck.reason}`,
             );
@@ -623,6 +634,8 @@ export default {
               modelOverride: live.noReplyModel,
             };
           }
+          // Allowed to speak - record this session as allowed
+          sessionAllowed.set(key, true);
         }
       }
 
@@ -679,7 +692,7 @@ export default {
         if (rec) sessionDecision.delete(key);
 
         const prompt = ((event as Record<string, unknown>).prompt as string) || "";
-        const derived = deriveDecisionInputFromPrompt(prompt, ctx.messageProvider);
+        const derived = deriveDecisionInputFromPrompt(prompt, ctx.messageProvider, ctx.channelId);
 
         const decision = evaluateDecision({
           config: live,
@@ -703,6 +716,17 @@ export default {
       }
 
       sessionDecision.delete(key);
+
+      // Only inject once per session (one-time injection)
+      if (sessionInjected.has(key)) {
+        if (shouldDebugLog(live, undefined)) {
+          api.logger.info(
+            `whispergate: debug before_prompt_build session=${key} inject skipped (already injected)`,
+          );
+        }
+        return;
+      }
+
       if (!rec.decision.shouldInjectEndMarkerPrompt) {
         if (shouldDebugLog(live, undefined)) {
           api.logger.info(
@@ -714,7 +738,7 @@ export default {
 
       // Resolve end symbols from config/policy for dynamic instruction
       const prompt = ((event as Record<string, unknown>).prompt as string) || "";
-      const derived = deriveDecisionInputFromPrompt(prompt, ctx.messageProvider);
+      const derived = deriveDecisionInputFromPrompt(prompt, ctx.messageProvider, ctx.channelId);
       const policy = resolvePolicy(live, derived.channelId, policyState.channelPolicies);
       const isGroupChat = derived.conv.is_group_chat === true || derived.conv.is_group_chat === "true";
       const instruction = buildEndMarkerInstruction(policy.endSymbols, isGroupChat);
@@ -726,6 +750,9 @@ export default {
         if (idStr) identity = idStr + "\n\n";
       }
 
+      // Mark session as injected (one-time injection)
+      sessionInjected.add(key);
+
       api.logger.info(`whispergate: prepend end marker instruction for session=${key}, reason=${rec.decision.reason} isGroupChat=${isGroupChat}`);
       return { prependContext: identity + instruction };
     });
@@ -776,6 +803,77 @@ export default {
       },
     });
 
+    // Handle NO_REPLY detection before message write
+    // This is where we detect if agent output is NO_REPLY and handle turn advancement
+    api.on("before_message_write", async (event, ctx) => {
+      try {
+        const key = ctx.sessionKey;
+        const channelId = ctx.channelId as string | undefined;
+        const accountId = ctx.accountId as string | undefined;
+
+        if (!key || !channelId || !accountId) return;
+
+        const live = getLivePluginConfig(api, baseConfig as WhisperGateConfig) as WhisperGateConfig & DebugConfig;
+
+        // Get the agent's output content
+        const content = (event.content as string) || "";
+        const trimmed = content.trim();
+        const isNoReply = /^NO_REPLY$/i.test(trimmed);
+
+        if (!isNoReply) return;
+
+        // Check if this session was forced no-reply or allowed to speak
+        const wasAllowed = sessionAllowed.get(key);
+        if (wasAllowed === undefined) return; // No record, skip
+
+        if (wasAllowed === false) {
+          // Forced no-reply - do not advance turn
+          sessionAllowed.delete(key);
+          if (shouldDebugLog(live, channelId)) {
+            api.logger.info(
+              `whispergate: before_message_write forced no-reply session=${key} channel=${channelId} - not advancing turn`,
+            );
+          }
+          return;
+        }
+
+        // Allowed to speak (current speaker) but chose NO_REPLY - advance turn
+        ensureTurnOrder(api, channelId);
+        const nextSpeaker = onSpeakerDone(channelId, accountId, true);
+
+        sessionAllowed.delete(key);
+
+        if (shouldDebugLog(live, channelId)) {
+          api.logger.info(
+            `whispergate: before_message_write real no-reply session=${key} channel=${channelId} nextSpeaker=${nextSpeaker ?? "dormant"}`,
+          );
+        }
+
+        // If all agents NO_REPLY'd (dormant), don't trigger handoff
+        if (!nextSpeaker) {
+          if (shouldDebugLog(live, channelId)) {
+            api.logger.info(
+              `whispergate: before_message_write all agents no-reply, going dormant - no handoff`,
+            );
+          }
+          return;
+        }
+
+        // Trigger moderator handoff message
+        if (live.moderatorBotToken) {
+          const nextUserId = resolveDiscordUserId(api, nextSpeaker);
+          if (nextUserId) {
+            const handoffMsg = `轮到（<@${nextUserId}>）了，如果没有想说的请直接回复NO_REPLY`;
+            sendModeratorMessage(live.moderatorBotToken, channelId, handoffMsg, api.logger);
+          } else {
+            api.logger.warn(`whispergate: cannot resolve Discord userId for next speaker accountId=${nextSpeaker}`);
+          }
+        }
+      } catch (err) {
+        api.logger.warn(`whispergate: before_message_write hook failed: ${String(err)}`);
+      }
+    });
+
     // Turn advance: when an agent sends a message, check if it signals end of turn
     api.on("message_sent", async (event, ctx) => {
       try {