More balanced adaptive drill generation, Tab fixes, mouse control tweaks

src/session/drill.rs

@@ -17,6 +17,7 @@ pub struct DrillState {
     pub finished_at: Option<Instant>,
     pub typo_flags: HashSet<usize>,
     pub synthetic_spans: Vec<SyntheticSpan>,
+    pub auto_indent_after_newline: bool,
 }
 
 impl DrillState {
@@ -29,6 +30,7 @@ impl DrillState {
             finished_at: None,
             typo_flags: HashSet::new(),
             synthetic_spans: Vec::new(),
+            auto_indent_after_newline: true,
         }
     }
 
@@ -263,6 +265,18 @@ mod tests {
         assert_eq!(drill.accuracy(), 100.0);
     }
 
+    #[test]
+    fn test_correct_enter_no_auto_indent_when_disabled() {
+        let mut drill = DrillState::new("if x:\n\tpass");
+        drill.auto_indent_after_newline = false;
+        for ch in "if x:".chars() {
+            input::process_char(&mut drill, ch);
+        }
+        input::process_char(&mut drill, '\n');
+        let expected_cursor = "if x:\n".chars().count();
+        assert_eq!(drill.cursor, expected_cursor);
+    }
+
     #[test]
     fn test_nested_synthetic_spans_collapse_to_single_error() {
         let mut drill = DrillState::new("abcd\nefgh");

src/session/input.rs

@@ -47,9 +47,9 @@ pub fn process_char(drill: &mut DrillState, ch: char) -> Option<KeystrokeEvent>
     } else if correct {
         drill.input.push(CharStatus::Correct);
         drill.cursor += 1;
-        // IDE-like behavior: when Enter is correctly typed, auto-consume
+        // Optional IDE-like behavior: when Enter is correctly typed, auto-consume
         // indentation whitespace on the next line.
-        if ch == '\n' {
+        if ch == '\n' && drill.auto_indent_after_newline {
             apply_auto_indent_after_newline(drill);
         }
     } else if ch == '\n' {