feat: add ellipsis when truncating strings and only apply max_len for terminal output

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/modes/common.rs

@@ -46,7 +46,30 @@ pub fn string_column(s: String, column_width: usize) -> String {
     if column_width > 0 {
         match s.char_indices().nth(column_width) {
             None => s.to_string(),
-            Some((idx, _)) => s[..idx].to_string(),
+            Some((idx, _)) => {
+                if column_width > 1 {
+                    // Find where to cut to fit the ellipsis
+                    let mut cut_idx = idx;
+                    // We need to make room for the ellipsis character
+                    // Find the character boundary before the cut index
+                    for i in (0..idx).rev() {
+                        if s.is_char_boundary(i) {
+                            if idx - i >= 3 { // Make sure we have enough room
+                                cut_idx = i;
+                                break;
+                            }
+                        }
+                    }
+                    // If we can't find a good place, just truncate without ellipsis
+                    if cut_idx >= 3 {
+                        format!("{}…", &s[..cut_idx - 1])
+                    } else {
+                        s[..idx].to_string()
+                    }
+                } else {
+                    s[..idx].to_string()
+                }
+            }
         }
     } else {
         s.to_string()

src/modes/list.rs

@@ -62,11 +62,17 @@ pub fn mode_list(
         return show_list_structured(items_with_meta, data_path, settings, output_format);
     }
 
+    // Check if output is a terminal
+    let is_terminal = stdout().is_terminal();
+    debug!("Output is terminal: {}", is_terminal);
+    
     // Get terminal width once, default to 80 if not available
-    let term_width = if let Ok(columns_env) = env::var("COLUMNS") {
+    // Only use max_len when output is a terminal
+    let term_width = if is_terminal {
+        if let Ok(columns_env) = env::var("COLUMNS") {
             debug!("COLUMNS environment variable: {:?}", columns_env);
             columns_env.parse::<usize>().unwrap_or(80)
-    } else if stdout().is_terminal() {
+        } else {
             // Try to get terminal size using termsize
             match termsize::get() {
                 Some(size) => {
@@ -79,9 +85,10 @@ pub fn mode_list(
                     80
                 }
             }
+        }
     } else {
-        debug!("Not a terminal, defaulting to 80");
-        80
+        debug!("Not a terminal, max_len will be ignored");
+        0  // Use 0 to indicate no truncation
     };
     
     debug!("Terminal width: {}", term_width);
@@ -114,7 +121,9 @@ pub fn mode_list(
             let mut meta_name: Option<&str> = None;
             
             // Parse max_len, handling numbers, percentages, and negative values
-            let column_width = if let Some(max_len_str) = &column.max_len {
+            // Only apply max_len when output is a terminal
+            let column_width = if is_terminal {
+                if let Some(max_len_str) = &column.max_len {
                     debug!("Processing max_len for column '{}': {}", column.name, max_len_str);
                     // Check if it's a negative number
                     if max_len_str.starts_with('-') {
@@ -142,6 +151,10 @@ pub fn mode_list(
                 } else {
                     debug!("No max_len specified for column '{}'", column.name);
                     0
+                }
+            } else {
+                debug!("Output is not a terminal, ignoring max_len");
+                0
             };
             
             debug!("Final column width for '{}': {}", column.name, column_width);