fix(cli): auto-create conversation on TUI start when no -c flag given

Without --conversation/-c, the TUI was starting with no conversationId,
leaving the session bar showing "No session" and gateway commands
unable to dispatch. Now creates a new conversation via REST before
rendering so the socket is immediately attached to an active session.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/cli/src/cli.ts

@@ -144,6 +144,23 @@ program
         }
       }
 
+      // Auto-create a conversation if none was specified
+      let conversationId = opts.conversation;
+      if (!conversationId) {
+        try {
+          const { createConversation } = await import('./tui/gateway-api.js');
+          const conv = await createConversation(opts.gateway, session.cookie, {
+            ...(projectId ? { projectId } : {}),
+          });
+          conversationId = conv.id;
+        } catch (err) {
+          console.error(
+            `Failed to create conversation: ${err instanceof Error ? err.message : String(err)}`,
+          );
+          process.exit(1);
+        }
+      }
+
       // Dynamic import to avoid loading React/Ink for other commands
       const { render } = await import('ink');
       const React = await import('react');
@@ -152,7 +169,7 @@ program
       render(
         React.createElement(TuiApp, {
           gatewayUrl: opts.gateway,
-          conversationId: opts.conversation,
+          conversationId,
           sessionCookie: session.cookie,
           initialModel: opts.model,
           initialProvider: opts.provider,

packages/cli/src/tui/gateway-api.ts

@@ -110,6 +110,31 @@ async function handleResponse<T>(res: Response, errorPrefix: string): Promise<T>
   return (await res.json()) as T;
 }
 
+// ── Conversation types ──
+
+export interface ConversationInfo {
+  id: string;
+  title: string | null;
+  archived: boolean;
+  createdAt: string;
+  updatedAt: string;
+}
+
+// ── Conversation endpoints ──
+
+export async function createConversation(
+  gatewayUrl: string,
+  sessionCookie: string,
+  data: { title?: string; projectId?: string } = {},
+): Promise<ConversationInfo> {
+  const res = await fetch(`${gatewayUrl}/api/conversations`, {
+    method: 'POST',
+    headers: jsonHeaders(sessionCookie, gatewayUrl),
+    body: JSON.stringify(data),
+  });
+  return handleResponse<ConversationInfo>(res, 'Failed to create conversation');
+}
+
 // ── Provider / Model endpoints ──
 
 export async function fetchAvailableModels(