fix: tool call cards persist across page reload (#140) (#149)

Tool cards disappeared on page refresh because assistant messages with
only tool_use content (no text) were filtered out of the visible
messages list. Since tool cards anchor to DOM rows via data-msg-idx,
removing the anchor row meant cards had nothing to attach to.

Fix: keep assistant messages in the render list if they contain
tool_use blocks, even when they have no text content. The row renders
with the role label but empty body, providing an anchor point for the
tool card insertion pass.

Fixes #140

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

static/ui.js

@@ -465,6 +465,9 @@ function renderMessages(){
   const inner=$('msgInner');
   const vis=S.messages.filter(m=>{
     if(!m||!m.role||m.role==='tool')return false;
+    // Keep assistant messages with tool_use content even if they have no text,
+    // so tool cards can be anchored to their DOM rows on page reload (#140).
+    if(m.role==='assistant'&&Array.isArray(m.content)&&m.content.some(p=>p&&p.type==='tool_use'))return true;
     return msgContent(m)||m.attachments?.length;
   });
   $('emptyState').style.display=vis.length?'none':'';