refactor: Improve change navigation with block-based approach and context scrolling

gtm

@@ -134,25 +134,47 @@ class AppState:
     wrap_lines: bool = True
     
     # Change navigation
-    change_positions: List[int] = field(default_factory=list)
+    change_blocks: List[Tuple[int, int]] = field(default_factory=list)  # (start_line, end_line) of each change block
     current_change_idx: int = -1  # -1 means no change is selected
 
 # --- Actions (Controller) ---
 
-def calculate_change_positions(state: AppState) -> AppState:
+def calculate_change_blocks(state: AppState) -> AppState:
-    """Calculate positions of all changes (additions and deletions) in the file."""
+    """Calculate positions of change blocks (consecutive changes) in the file."""
-    positions = []
+    if not state.added_lines and not state.deleted_lines:
-    # Add positions of added lines
+        return replace(state, change_blocks=[], current_change_idx=-1)
+        
+    # Collect all change positions
+    all_changes = []
     for line_num, _ in state.added_lines:
-        if line_num not in positions:
+        all_changes.append(line_num)
-            positions.append(line_num)
-    # Add positions of deleted lines
     for line_num, _ in state.deleted_lines:
-        if line_num not in positions:
+        all_changes.append(line_num)
-            positions.append(line_num)
+    
-    # Sort positions
+    # Sort all positions
-    positions.sort()
+    all_changes.sort()
-    return replace(state, change_positions=positions, current_change_idx=-1)
+    
+    if not all_changes:
+        return replace(state, change_blocks=[], current_change_idx=-1)
+    
+    # Group into blocks (changes within 3 lines of each other are considered one block)
+    blocks = []
+    current_block_start = all_changes[0]
+    current_block_end = all_changes[0]
+    
+    for pos in all_changes[1:]:
+        if pos <= current_block_end + 3:  # Within 3 lines of previous change
+            current_block_end = pos
+        else:
+            # Start a new block
+            blocks.append((current_block_start, current_block_end))
+            current_block_start = pos
+            current_block_end = pos
+    
+    # Add the last block
+    blocks.append((current_block_start, current_block_end))
+    
+    return replace(state, change_blocks=blocks, current_change_idx=-1)
 
 def load_commit_content(state: AppState) -> AppState:
     if not state.commits:
@@ -199,8 +221,8 @@ def load_commit_content(state: AppState) -> AppState:
         right_scroll_offset=right_scroll_offset
     )
     
-    # Calculate change positions for navigation
+    # Calculate change blocks for navigation
-    return calculate_change_positions(new_state)
+    return calculate_change_blocks(new_state)
 
 def update_dimensions(state: AppState, height: int, width: int) -> AppState:
     return replace(state, height=height, width=width)
@@ -263,52 +285,54 @@ def draw_left_pane(stdscr, state):
             stdscr.attroff(curses.A_REVERSE)
 
 def jump_to_next_change(state: AppState) -> AppState:
-    """Jump to the next change after the current scroll position."""
+    """Jump to the next change block after the current scroll position."""
-    if not state.change_positions:
+    if not state.change_blocks:
         return state
     
-    # Find the next change after current position
+    # Find the next change block after current position
     current_pos = state.right_scroll_offset
     next_idx = -1
-    for i, pos in enumerate(state.change_positions):
+    for i, (start_pos, _) in enumerate(state.change_blocks):
-        if pos > current_pos:
+        if start_pos > current_pos:
             next_idx = i
             break
     
     # If no next change found, wrap to the first change
-    if next_idx == -1 and state.change_positions:
+    if next_idx == -1 and state.change_blocks:
         next_idx = 0
     
     if next_idx != -1:
-        new_scroll = state.change_positions[next_idx]
+        # Get the start position of the change block
+        new_scroll = max(0, state.change_blocks[next_idx][0] - 3)  # Show 3 lines of context above
         return replace(state, right_scroll_offset=new_scroll, current_change_idx=next_idx)
     return state
 
 def jump_to_prev_change(state: AppState) -> AppState:
-    """Jump to the previous change before the current scroll position."""
+    """Jump to the previous change block before the current scroll position."""
-    if not state.change_positions:
+    if not state.change_blocks:
         return state
     
-    # Find the previous change before current position
+    # Find the previous change block before current position
     current_pos = state.right_scroll_offset
     prev_idx = -1
-    for i in range(len(state.change_positions) - 1, -1, -1):
+    for i in range(len(state.change_blocks) - 1, -1, -1):
-        if state.change_positions[i] < current_pos:
+        if state.change_blocks[i][0] < current_pos:
             prev_idx = i
             break
     
     # If no previous change found, wrap to the last change
-    if prev_idx == -1 and state.change_positions:
+    if prev_idx == -1 and state.change_blocks:
-        prev_idx = len(state.change_positions) - 1
+        prev_idx = len(state.change_blocks) - 1
     
     if prev_idx != -1:
-        new_scroll = state.change_positions[prev_idx]
+        # Get the start position of the change block
+        new_scroll = max(0, state.change_blocks[prev_idx][0] - 3)  # Show 3 lines of context above
         return replace(state, right_scroll_offset=new_scroll, current_change_idx=prev_idx)
     return state
 
 def draw_change_markers(stdscr, state):
     """Draw markers in the scrollbar area to indicate where changes are located."""
-    if not state.change_positions or not (state.show_whole_diff or state.show_additions or state.show_deletions):
+    if not state.change_blocks or not (state.show_whole_diff or state.show_additions or state.show_deletions):
         return
     
     right_start = 0 if not state.show_sidebar else state.divider_col + 2
@@ -323,14 +347,11 @@ def draw_change_markers(stdscr, state):
     scale_factor = (state.height - 1) / total_lines
     
     # Draw markers
-    for i, pos in enumerate(state.change_positions):
+    for i, (start_pos, _) in enumerate(state.change_blocks):
-        marker_y = int(pos * scale_factor)
+        marker_y = int(start_pos * scale_factor)
         if 0 <= marker_y < state.height - 1:
-            # Determine marker color based on change type
+            # Use a single color for change blocks
-            is_addition = any(added_line_num == pos for added_line_num, _ in state.added_lines)
+            attr = curses.color_pair(5)  # New color pair for change blocks
-            is_deletion = any(del_line_num == pos for del_line_num, _ in state.deleted_lines)
-            
-            attr = curses.color_pair(3) if is_addition else curses.color_pair(4)
             marker_char = '>' if i == state.current_change_idx else '|'
             
             try:
@@ -516,8 +537,8 @@ def draw_status_bars(stdscr, state):
     # Add wrap indicator and change position to commit message
     wrap_indicator = " [W] " if state.wrap_lines else " [NW] "
     change_indicator = ""
-    if state.change_positions and state.current_change_idx != -1:
+    if state.change_blocks and state.current_change_idx != -1:
-        change_indicator = f" [Change {state.current_change_idx + 1}/{len(state.change_positions)}] "
+        change_indicator = f" [Block {state.current_change_idx + 1}/{len(state.change_blocks)}] "
     
     commit_message = wrap_indicator + change_indicator + commit_message
     
@@ -594,7 +615,9 @@ def draw_ui(stdscr, state):
     draw_left_pane(stdscr, state)
     draw_right_pane(stdscr, state)
     draw_divider(stdscr, state)
-    draw_change_markers(stdscr, state)
+    # Only draw change markers in the right pane
+    if state.focus == "right":
+        draw_change_markers(stdscr, state)
     draw_status_bars(stdscr, state)
     draw_selection(stdscr, state)
     stdscr.refresh()
@@ -795,8 +818,9 @@ def main(stdscr, filename, show_diff, show_add, show_del, mouse, wrap_lines=True
         # Use a safe background color (7 or less) to avoid "Color number is greater than COLORS-1" error
         curses.init_pair(1, curses.COLOR_BLACK, 7)  # Active pane: black on white
         curses.init_pair(2, curses.COLOR_WHITE, 0)  # Inactive pane: white on black
-        curses.init_pair(3, curses.COLOR_GREEN, -1)
+        curses.init_pair(3, curses.COLOR_GREEN, -1)  # Added lines
-        curses.init_pair(4, curses.COLOR_RED, -1)
+        curses.init_pair(4, curses.COLOR_RED, -1)    # Deleted lines
+        curses.init_pair(5, curses.COLOR_YELLOW, -1) # Change block markers
 
     height, width = stdscr.getmaxyx()
     state = AppState(