🎨 Palette: Improve score readability and UI consistency

.Jules/palette.md

@@ -29,3 +29,7 @@
 ## 2025-01-24 - Real-time Achievement Feedback in CLI
 **Learning:** In terminal-based games, displaying achievement progress (like a live high score) in real-time provides immediate tactile reward and engagement. Furthermore, inclusive UX means ensuring first-time players also receive "New Best" feedback, even when their initial record is zero.
 **Action:** Update session-high-score variables immediately upon record-breaking and display them in the live HUD. Ensure achievement conditions (`score > highscore`) don't exclude the first-time user experience.
+
+## 2026-05-24 - Preventing Visual Artifacts in CLI
+**Learning:** Using carriage returns (`\r`) for in-place terminal updates can leave "ghost characters" if the new line is shorter than the previous one. The ANSI 'Erase in Line' sequence (`\033[K`), or `CLR_EOL`, is a more robust solution than space-padding as it guarantees a clean line regardless of terminal width or previous content.
+**Action:** Use `CLR_EOL` at the end of every `\r` update line to ensure a clean visual transition, especially during state changes like countdowns or score magnitude shifts.

src/main.cpp

@@ -20,6 +20,7 @@
 #define CLR_HARD  "\033[1;31m"
 #define CLR_NORM  "\033[1;32m"
 #define CLR_CTRL  "\033[1;33m"
+#define CLR_EOL   "\033[K"
 #define CLR_RESET "\033[0m"
 
 struct termios oldt;
@@ -50,6 +51,17 @@ void save_highscore(long long score) {
     }
 }
 
+std::string formatWithCommas(long long value) {
+    std::string s = std::to_string(value);
+    int insertPosition = static_cast<int>(s.length()) - 3;
+    int limit = (value < 0) ? 1 : 0;
+    while (insertPosition > limit) {
+        s.insert(insertPosition, ",");
+        insertPosition -= 3;
+    }
+    return s;
+}
+
 int main() {
     struct termios newt;
     if (tcgetattr(STDIN_FILENO, &oldt) == -1) {
@@ -77,7 +89,7 @@ int main() {
     std::cout << CLR_CTRL << "==========================\n      SPEED CLICKER\n==========================\n" << CLR_RESET;
 
     if (highscore > 0) {
-        std::cout << " Personal Best: " << CLR_SCORE << highscore << CLR_RESET << "\n\n";
+        std::cout << " Personal Best: " << CLR_SCORE << formatWithCommas(highscore) << CLR_RESET << "\n\n";
     }
 
     std::cout << "Controls:\n " << CLR_CTRL << "[h]" << CLR_RESET << " Toggle Hard Mode (10x Speed!)\n "
@@ -94,7 +106,7 @@ int main() {
     }
 
     for (int i = 3; i > 0; --i) {
-        std::cout << "\rStarting in " << CLR_CTRL << i << CLR_RESET << "... " << std::flush;
+        std::cout << "\rStarting in " << CLR_CTRL << i << CLR_RESET << "... " << CLR_EOL << std::flush;
         auto start_wait = std::chrono::steady_clock::now();
         while (std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - start_wait).count() < 1000) {
             int elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - start_wait).count();
@@ -108,7 +120,7 @@ int main() {
             }
         }
     }
-    std::cout << "\r" << CLR_NORM << "GO!             " << CLR_RESET << "\n" << std::flush;
+    std::cout << "\r" << CLR_NORM << "GO!             " << CLR_RESET << CLR_EOL << "\n" << std::flush;
     std::this_thread::sleep_for(std::chrono::milliseconds(200));
     tcflush(STDIN_FILENO, TCIFLUSH);
 
@@ -141,10 +153,11 @@ int main() {
         }
 
         if (updateUI) {
-            std::cout << "\r" << CLR_SCORE << "Score: " << score << CLR_RESET << " | High: " << highscore << " "
+            std::cout << "\r" << CLR_SCORE << "Score: " << formatWithCommas(score)
+                      << CLR_RESET << " | " << CLR_SCORE << "High: " << formatWithCommas(highscore) << CLR_RESET << " "
                       << (hardMode ? CLR_HARD "[HARD MODE]" : CLR_NORM "[NORMAL MODE]")
                       << (score > initialHighscore ? " NEW BEST! 🥳" : "")
-                      << "           " << std::flush;
+                      << CLR_EOL << std::flush;
             updateUI = false;
         }
     }
@@ -154,9 +167,13 @@ int main() {
     }
 
     tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
-    std::cout << "\n\n" << CLR_SCORE << "Final Score: " << score << CLR_RESET << "\n";
+    std::cout << "\n\n" << CLR_SCORE << "Final Score: " << formatWithCommas(score) << CLR_RESET << "\n";
     if (score > initialHighscore) {
-        std::cout << "Congratulations! A new personal best!\n";
+        std::cout << CLR_NORM << "Congratulations! A new personal best!" << CLR_RESET;
+        if (initialHighscore > 0) {
+            std::cout << " (Previous: " << CLR_SCORE << formatWithCommas(initialHighscore) << CLR_RESET << ")";
+        }
+        std::cout << "\n";
     }
     std::cout << "Thanks for playing!\n";
     std::cout << "\033[?25h" << std::flush;