story-kit: merge 162_story_colored_server_terminal_log_output

server/src/log_buffer.rs

@@ -53,6 +53,17 @@ impl LogEntry {
     pub fn formatted(&self) -> String {
         format!("{} [{}] {}", self.timestamp, self.level.as_str(), self.message)
     }
+
+    /// Format with ANSI color codes for terminal output.
+    /// WARN is yellow, ERROR is red, INFO has no color.
+    fn colored_formatted(&self) -> String {
+        let line = self.formatted();
+        match self.level {
+            LogLevel::Warn => format!("\x1b[33m{line}\x1b[0m"),
+            LogLevel::Error => format!("\x1b[31m{line}\x1b[0m"),
+            LogLevel::Info => line,
+        }
+    }
 }
 
 pub struct LogBuffer {
@@ -74,8 +85,7 @@ impl LogBuffer {
             timestamp,
             message,
         };
-        let line = entry.formatted();
+        eprintln!("{}", entry.colored_formatted());
-        eprintln!("{line}");
         if let Ok(mut buf) = self.entries.lock() {
             if buf.len() >= CAPACITY {
                 buf.pop_front();
@@ -295,4 +305,62 @@ mod tests {
         assert_eq!(LogLevel::from_str_ci("info"), Some(LogLevel::Info));
         assert_eq!(LogLevel::from_str_ci("DEBUG"), None);
     }
+
+    #[test]
+    fn colored_formatted_warn_has_yellow_ansi() {
+        let entry = LogEntry {
+            level: LogLevel::Warn,
+            timestamp: "2026-01-01T00:00:00Z".into(),
+            message: "test warning".into(),
+        };
+        let colored = entry.colored_formatted();
+        assert!(colored.starts_with("\x1b[33m"), "WARN should start with yellow ANSI code");
+        assert!(colored.ends_with("\x1b[0m"), "WARN should end with ANSI reset");
+        assert!(colored.contains("[WARN]"));
+        assert!(colored.contains("test warning"));
+    }
+
+    #[test]
+    fn colored_formatted_error_has_red_ansi() {
+        let entry = LogEntry {
+            level: LogLevel::Error,
+            timestamp: "2026-01-01T00:00:00Z".into(),
+            message: "test error".into(),
+        };
+        let colored = entry.colored_formatted();
+        assert!(colored.starts_with("\x1b[31m"), "ERROR should start with red ANSI code");
+        assert!(colored.ends_with("\x1b[0m"), "ERROR should end with ANSI reset");
+        assert!(colored.contains("[ERROR]"));
+        assert!(colored.contains("test error"));
+    }
+
+    #[test]
+    fn colored_formatted_info_has_no_ansi() {
+        let entry = LogEntry {
+            level: LogLevel::Info,
+            timestamp: "2026-01-01T00:00:00Z".into(),
+            message: "test info".into(),
+        };
+        let colored = entry.colored_formatted();
+        assert!(!colored.contains("\x1b["), "INFO should have no ANSI escape codes");
+        assert!(colored.contains("[INFO]"));
+        assert!(colored.contains("test info"));
+    }
+
+    #[test]
+    fn ring_buffer_entries_have_no_ansi_codes() {
+        let buf = fresh_buffer();
+        buf.push_entry(LogLevel::Info, "info msg".into());
+        buf.push_entry(LogLevel::Warn, "warn msg".into());
+        buf.push_entry(LogLevel::Error, "error msg".into());
+
+        let recent = buf.get_recent(10, None, None);
+        assert_eq!(recent.len(), 3);
+        for line in &recent {
+            assert!(
+                !line.contains("\x1b["),
+                "Ring buffer entry should not contain ANSI codes: {line}"
+            );
+        }
+    }
 }