fix that the cli still used the DEFAULT_SOCKET Const, give better error message when no browser found adding test for client and update cli test, and update version and readme

browser_cli/client.py

@@ -6,7 +6,7 @@ Profile selection order:
   1. Explicit `profile` argument to send_command()
   2. BROWSER_CLI_PROFILE environment variable
   3. First entry in /tmp/.browser_cli/registry.json
-  4. Fallback: /tmp/.browser_cli/default.sock
+  4. Otherwise, no browser can be resolved automatically
 """
 import json
 import os
@@ -18,7 +18,6 @@ from typing import Any
 
 SOCKET_DIR = Path("/tmp/.browser_cli")
 REGISTRY_PATH = SOCKET_DIR / "registry.json"
-DEFAULT_SOCKET = str(SOCKET_DIR / "default.sock")
 
 
 class BrowserNotConnected(Exception):
@@ -64,7 +63,11 @@ def _resolve_socket(profile: str | None = None) -> str:
         except Exception:
             pass
 
-    return DEFAULT_SOCKET
+    raise BrowserNotConnected(
+        "Cannot resolve a browser socket automatically.\n"
+        "Make sure the browser is running with the browser-cli extension enabled,\n"
+        "or pass --browser <alias> / set BROWSER_CLI_PROFILE to a known alias."
+    )
 
 
 def send_command(command: str, args: dict | None = None, profile: str | None = None) -> Any: