A separate statement doesn't compose with complex patterns. I'd prefer always requiring the walrus operator to capture:

    match response:
      case (not_found, msg := _):
        return f"Not found: {msg}"
      case (error, "No swizzle available"):
        return "We lack swizzle. :-("
      case pair := (_, "Swizzle"):
        log(f"Unexpected swizzle: {pair}")
        return f"Swizzle?"
      case ((code := _), _):
        return f"Success: {code}"