fix: advance turn in before_message_write to prevent race condition

When a speaker finishes with an end symbol, the turn was only advanced
in the message_sent hook. But by that time, the message had already been
broadcast to other agents, whose before_model_resolve ran with the old
turn state, causing them to be blocked by the turn gate (forced no-reply).

Fix:
- Move turn advance for both NO_REPLY and end-symbol cases to
  before_message_write, which fires before the message is broadcast.
- Only the current speaker's before_message_write advances the turn.
  Other agents (forced no-reply or not in turn) are skipped early.
- Use sessionTurnHandled set to prevent double-advancing in message_sent.

dist/whispergate/index.ts

@@ -960,6 +960,17 @@ export default {
 
         if (!key || !channelId || !accountId) return;
 
+        // Only the current speaker should advance the turn.
+        // Other agents also trigger before_message_write (for incoming messages or forced no-reply),
+        // but they must not affect turn state.
+        const currentTurn = getTurnDebugInfo(channelId);
+        if (currentTurn.currentSpeaker !== accountId) {
+          api.logger.info(
+            `whispergate: before_message_write skipping non-current-speaker session=${key} accountId=${accountId} currentSpeaker=${currentTurn.currentSpeaker}`,
+          );
+          return;
+        }
+
         const live = getLivePluginConfig(api, baseConfig as WhisperGateConfig) as WhisperGateConfig & DebugConfig;
         ensurePolicyStateLoaded(api, live);
         const policy = resolvePolicy(live, channelId, policyState.channelPolicies);

plugin/index.ts

@@ -960,6 +960,17 @@ export default {
 
         if (!key || !channelId || !accountId) return;
 
+        // Only the current speaker should advance the turn.
+        // Other agents also trigger before_message_write (for incoming messages or forced no-reply),
+        // but they must not affect turn state.
+        const currentTurn = getTurnDebugInfo(channelId);
+        if (currentTurn.currentSpeaker !== accountId) {
+          api.logger.info(
+            `whispergate: before_message_write skipping non-current-speaker session=${key} accountId=${accountId} currentSpeaker=${currentTurn.currentSpeaker}`,
+          );
+          return;
+        }
+
         const live = getLivePluginConfig(api, baseConfig as WhisperGateConfig) as WhisperGateConfig & DebugConfig;
         ensurePolicyStateLoaded(api, live);
         const policy = resolvePolicy(live, channelId, policyState.channelPolicies);