fix: false Connection lost message after settled stream disconnect — v0.50.59

* fix: 避免流结束后误插入 Connection lost 错误

* chore: bump version to v0.50.59, update CHANGELOG

---------

Co-authored-by: fiver <fiver@example.com>
Co-authored-by: Hermes Agent <agent@hermes>

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Hermes Web UI -- Changelog
 
+## [v0.50.59] — 2026-04-16
+
+### Fixed
+- **False "Connection lost" message after settled stream** — the UI no longer injects a fake `**Error:** Connection lost` assistant message when an SSE connection drops after the stream already completed normally. The fix tracks terminal stream states (`done`, `stream_end`, `cancel`, `apperror`) and, on a disconnect, fetches `/api/session` to confirm the session is settled before silently restoring it instead of calling the error path. Real failures still go through the error path as before. (Fixes #561, PR #562 by @halmisen)
+
 ## [v0.50.58] — 2026-04-16
 
 ### Fixed

static/index.html

@@ -553,7 +553,7 @@
                 <div class="settings-section-title">System</div>
                 <div class="settings-section-meta">Instance version and access controls.</div>
               </div>
-              <span class="settings-version-badge">v0.50.58</span>
+              <span class="settings-version-badge">v0.50.59</span>
             </div>
             <div class="settings-field" style="border-top:1px solid var(--border);padding-top:12px;margin-top:8px">
               <label for="settingsPassword" data-i18n="settings_label_password">Access Password</label>

static/messages.js

@@ -213,6 +213,7 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
 
   // ── Shared SSE handler wiring (used for initial connection and reconnect) ──
   let _reconnectAttempted=false;
+  let _terminalStateReached=false;
 
   // rAF-throttled rendering: buffer tokens, render at most once per frame
   let _renderPending=false;
@@ -412,6 +413,7 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
     });
 
     source.addEventListener('done',e=>{
+      _terminalStateReached=true;
       const d=JSON.parse(e.data);
       delete INFLIGHT[activeSid];
       clearInflight();clearInflightState(activeSid);
@@ -454,6 +456,7 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
     });
 
     source.addEventListener('stream_end',e=>{
+      _terminalStateReached=true;
       try{
         const d=JSON.parse(e.data||'{}');
         if((d.session_id||activeSid)!==activeSid) return;
@@ -473,6 +476,7 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
     });
 
     source.addEventListener('apperror',e=>{
+      _terminalStateReached=true;
       // Application-level error sent explicitly by the server (rate limit, crash, etc.)
       // This is distinct from the SSE network 'error' event below.
       source.close();
@@ -514,8 +518,12 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
       }catch(_){}
     });
 
-    source.addEventListener('error',e=>{
+    source.addEventListener('error',async e=>{
       source.close();
+      if(_terminalStateReached){
+        _closeSource();
+        return;
+      }
       // Attempt one reconnect if the stream is still active server-side
       if(!_reconnectAttempted && streamId){
         _reconnectAttempted=true;
@@ -529,14 +537,17 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
               return;
             }
           }catch(_){}
+          if(await _restoreSettledSession()) return;
           _handleStreamError();
         },1500);
         return;
       }
+      if(await _restoreSettledSession()) return;
       _handleStreamError();
     });
 
     source.addEventListener('cancel',e=>{
+      _terminalStateReached=true;
       source.close();
       delete INFLIGHT[activeSid];clearInflight();clearInflightState(activeSid);stopApprovalPolling();stopClarifyPolling();
       if(!_approvalSessionId||_approvalSessionId===activeSid) hideApprovalCard(true);
@@ -553,6 +564,29 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
     });
   }
 
+  async function _restoreSettledSession(){
+    try{
+      const data=await api(`/api/session?session_id=${encodeURIComponent(activeSid)}`);
+      const session=data&&data.session;
+      if(!session) return false;
+      if(session.active_stream_id||session.pending_user_message) return false;
+      delete INFLIGHT[activeSid];clearInflight();clearInflightState(activeSid);stopApprovalPolling();stopClarifyPolling();
+      _closeSource();
+      if(!_approvalSessionId||_approvalSessionId===activeSid) hideApprovalCard(true);
+      if(!_clarifySessionId||_clarifySessionId===activeSid) hideClarifyCard(true);
+      if(S.session&&S.session.session_id===activeSid){
+        S.activeStreamId=null;const _cbe=$('btnCancel');if(_cbe)_cbe.style.display='none';
+        clearLiveToolCards();if(!assistantText)removeThinking();
+        S.session=session;S.messages=session.messages||[];
+        syncTopbar();renderMessages();
+      }
+      renderSessionList();setBusy(false);setComposerStatus('');
+      return true;
+    }catch(_){
+      return false;
+    }
+  }
+
   function _handleStreamError(){
     delete INFLIGHT[activeSid];clearInflight();clearInflightState(activeSid);stopApprovalPolling();stopClarifyPolling();
     _closeSource();