web: send startup output to browser Tcl console

Move WebServer::serve() before showSplash() so the WebLogSink
captures all Logger output from the start.  Buffer pending log
lines when no browser is connected yet, then flush the accumulated
output when the first WebSocket session accepts.

Signed-off-by: Matt Liberty <mliberty@precisioninno.com>

Author: maliberty

src/Main.cc

@@ -381,22 +381,8 @@ static int tclAppInit(int& argc,
     ord::initOpenRoad(
         interp, log_filename, metrics_filename, exit_after_cmd_file);
 
-    bool no_splash = findCmdLineFlag(argc, argv, "-no_splash");
-    if (!no_splash) {
-      showSplash();
-    }
-
-    const char* threads = findCmdLineKey(argc, argv, "-threads");
-    if (threads) {
-      ord::OpenRoad::openRoad()->setThreadCount(threads, !no_splash);
-    } else {
-      // set to default number of threads
-      ord::OpenRoad::openRoad()->setThreadCount(
-          ord::OpenRoad::openRoad()->getThreadCount(), false);
-    }
-
-    // Start the web server before sourcing the script so the user can
-    // watch execution in real-time (analogous to -gui).
+    // Start the web server before splash/thread output so the
+    // WebLogSink captures all startup messages for the browser console.
     if (web_enabled) {
       int port = 0;
       if (web_port_arg) {
@@ -411,6 +397,20 @@ static int tclAppInit(int& argc,
       ord::OpenRoad::openRoad()->getWebServer()->serve(port);
     }
 
+    bool no_splash = findCmdLineFlag(argc, argv, "-no_splash");
+    if (!no_splash) {
+      showSplash();
+    }
+
+    const char* threads = findCmdLineKey(argc, argv, "-threads");
+    if (threads) {
+      ord::OpenRoad::openRoad()->setThreadCount(threads, !no_splash);
+    } else {
+      // set to default number of threads
+      ord::OpenRoad::openRoad()->setThreadCount(
+          ord::OpenRoad::openRoad()->getThreadCount(), false);
+    }
+
     // gui::Gui::enabled() is true when a HeadlessViewer is installed
     // (which the web server does).  But addRestoreStateCommand() only
     // works with the Qt event loop — the web server executes scripts

src/web/src/web.cpp

@@ -445,6 +445,10 @@ void WebSocketSession::on_accept(beast::error_code ec)
           }
           net::post(self->strand_, std::move(fn));
         });
+
+    // Flush any log output that accumulated before this client
+    // connected (splash screen, script output, etc.).
+    viewer_hook_->drainLogs();
   }
 
   // Build search indices in the background; tiles render without shapes

src/web/src/web_serve.cpp

@@ -86,6 +86,11 @@ class WebLogSink : public spdlog::sinks::base_sink<std::mutex>
     if (pending_.empty()) {
       return;
     }
+    // Keep accumulating when nobody is listening so the first
+    // client that connects receives the full startup output.
+    if (!hook_->sessions().hasClients()) {
+      return;
+    }
     while (!pending_.empty()
            && (pending_.back() == '\n' || pending_.back() == '\r')) {
       pending_.pop_back();

src/web/src/web_viewer_hook.cpp

@@ -262,6 +262,13 @@ bool WebViewerHook::isPaused() const
   return paused_.load(std::memory_order_acquire);
 }
 
+void WebViewerHook::drainLogs()
+{
+  if (drain_logs_) {
+    drain_logs_();
+  }
+}
+
 void WebViewerHook::setDrainLogsFn(DrainLogsFn fn)
 {
   drain_logs_ = std::move(fn);

src/web/src/web_viewer_hook.h

@@ -86,6 +86,9 @@ class WebViewerHook : public gui::HeadlessViewer
 
   SessionRegistry& sessions() { return sessions_; }
 
+  // Flush accumulated log output to all connected clients.
+  void drainLogs();
+
   // --- gui::HeadlessViewer ---
   void redraw() override;
   void pause(int timeout_ms) override;