From 9a12b1b1948b4ea6803a2c5e33b4df6388812b4f Mon Sep 17 00:00:00 2001
From: csh <caoshenghui@tinysoft.com.cn>
Date: Sun, 14 Dec 2025 13:43:56 +0800
Subject: [PATCH] :bug: fix(logging): support --log-stderr and clarify stdin
 wait

- Make logs go to stderr by default (keep LSP stdout clean).
- Add --log-stderr/--log-stdout flags and wire config.use_stderr into spdlog.
- Log an explicit message when waiting for LSP input on stdin.
---
 lsp-server/src/core/server.cppm       |  1 +
 lsp-server/src/utils/args_parser.cppm | 19 ++++++++++++-------
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/lsp-server/src/core/server.cppm b/lsp-server/src/core/server.cppm
index 133f5a9..239ab9b 100644
--- a/lsp-server/src/core/server.cppm
+++ b/lsp-server/src/core/server.cppm
@@ -112,6 +112,7 @@ namespace lsp::core
     void LspServer::Run()
     {
         spdlog::info("LSP server starting main loop...");
+        spdlog::info("Waiting for LSP messages on stdin...");
 
 // 设置二进制模式
 #ifdef _WIN32
diff --git a/lsp-server/src/utils/args_parser.cppm b/lsp-server/src/utils/args_parser.cppm
index 77b6e5e..4cc5d95 100644
--- a/lsp-server/src/utils/args_parser.cppm
+++ b/lsp-server/src/utils/args_parser.cppm
@@ -52,7 +52,9 @@ namespace lsp::utils
     const ServerConfig& ArgsParser::Parse(int argc, char* argv[])
     {
         config_ = ServerConfig{};
-        bool use_stdio = false;
+        // Default to stderr so LSP stdio (stdout) stays clean.
+        config_.use_stderr = true;
+
         for (int i = 1; i < argc; ++i)
         {
             std::string arg = argv[i];
@@ -75,10 +77,14 @@ namespace lsp::utils
                 config_.log_level = spdlog::level::err;
             else if (arg == "--log=off")
                 config_.log_level = spdlog::level::off;
+            else if (arg == "--log-stderr")
+                config_.use_stderr = true;
+            else if (arg == "--log-stdout")
+                config_.use_stderr = false;
             else if (arg.find("--log-file=") == 0)
                 config_.log_file = arg.substr(std::strlen("--log-file="));
             else if (arg == "--use-stdio")
-                use_stdio = true;
+                config_.use_stderr = true;
             else if (arg.find("--threads=") == 0)
             {
                 auto value = arg.substr(std::strlen("--threads="));
@@ -90,9 +96,6 @@ namespace lsp::utils
             }
         }
 
-        if (!use_stdio)
-            config_.use_stderr = true;
-
         return config_;
     }
 
@@ -113,7 +116,7 @@ namespace lsp::utils
         }
         else
         {
-            auto console_logger = spdlog::stdout_logger_mt("console_logger");
+            auto console_logger = config.use_stderr ? spdlog::stderr_logger_mt("console_logger") : spdlog::stdout_logger_mt("console_logger");
             console_logger->set_level(config.log_level);
             spdlog::set_default_logger(console_logger);
         }
@@ -127,8 +130,10 @@ namespace lsp::utils
                   << "Options:\\n"
                   << "  --help                Show this help message\\n"
                   << "  --log=<level>         Set log level (trace, debug, info, warn, error, off)\\n"
+                  << "  --log-stderr          Output logs to stderr (default)\\n"
+                  << "  --log-stdout          Output logs to stdout\\n"
                   << "  --log-file=<path>     Output logs to specified file\\n"
-                  << "  --use-stdio           Use stdin/stdout for I/O (default: stderr)\\n"
+                  << "  --use-stdio           Alias for --log-stderr (keep stdout clean for LSP)\\n"
                   << "  --threads=<count>     Number of worker threads\\n"
                   << "  --interpreter=<path>  Custom interpreter path\\n";
     }