fix(claude-cli): --resume for continuing turns (reusing --session-id errored on turn 2)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/api/routes/companion.js

@@ -52,6 +52,11 @@ spacesScopedRouter.post('/turn',
     const { agent, convo } = await resolveConversation(req.params.space_id);
     const { text, view } = req.body;
 
+    // Resume the claude session if this conversation already had turns (the CLI
+    // keys session history by --session-id; first turn creates it, rest --resume).
+    const priorTurns = (await messages.listByConversation(convo.id)).length;
+    const resume = priorTurns > 0;
+
     await messages.append(convo.id, { role: 'user', body: text });
 
     res.writeHead(200, {
@@ -105,6 +110,7 @@ spacesScopedRouter.post('/turn',
     try {
       result = await runClaudeTurn({
         sessionId: convo.id,
+        resume,
         systemPrompt: SYSTEM,
         userText: text,
         mcpConfigPath,