fix(fs_write): suppress spurious trailing-newline diff lines

When the only difference between the old and new file content is a
trailing newline, similar::TextDiff produces a Delete/Insert pair for
the last line that clutters the diff output shown to the user.

Normalize both sides with trim_end_matches('\n') before diffing so
that a trailing-newline-only change is not shown as a modification.

Fixes #923

Author: sandikodev

crates/chat-cli/src/cli/chat/tools/fs_write.rs

@@ -641,7 +641,11 @@ fn print_diff(
     new_str: &StylizedFile,
     start_line: usize,
 ) -> Result<()> {
-    let diff = similar::TextDiff::from_lines(&old_str.content, &new_str.content);
+    // Normalize trailing newlines so that a file ending with "\n" vs without one does not
+    // produce a spurious diff line. See: #923
+    let old_content = old_str.content.trim_end_matches('\n');
+    let new_content = new_str.content.trim_end_matches('\n');
+    let diff = similar::TextDiff::from_lines(old_content, new_content);
 
     // First, get the gutter width required for both the old and new lines.
     let (mut max_old_i, mut max_new_i) = (1, 1);