Function apply_hunks

crates/opencode-tool/src/apply_patch.rs:639–727

(original: &str, hunks: &[Hunk])

}

fn apply_hunks(original: &str, hunks: &[Hunk]) -> Result<String, ToolError> {
    let mut lines: Vec<String> = original.lines().map(|s| s.to_string()).collect();
    let mut offset = 0isize;

    for hunk in hunks {
        // Validate hunk line counts against declared counts
        let actual_old = hunk
            .lines
            .iter()
            .filter(|l| matches!(l, PatchLine::Remove(_) | PatchLine::Context(_)))
            .count();
        let actual_new = hunk
            .lines
            .iter()
            .filter(|l| matches!(l, PatchLine::Add(_) | PatchLine::Context(_)))
            .count();

        if hunk.old_count > 0 && actual_old != hunk.old_count {
            tracing::warn!(
                "Hunk old_count mismatch: declared {} but found {} lines",
                hunk.old_count,
                actual_old
            );
        }
        if hunk.new_count > 0 && actual_new != hunk.new_count {
            tracing::warn!(
                "Hunk new_count mismatch: declared {} but found {} lines",
                hunk.new_count,
                actual_new
            );
        }

        let start = (hunk.old_start as isize + offset - 1).max(0) as usize;

        // Cross-check: expected new position should align with new_start
        let expected_new_pos = (hunk.new_start as isize - 1).max(0) as usize;
        if hunk.new_start > 0 && start != expected_new_pos && offset != 0 {
            tracing::debug!(
                "Hunk position drift: old_start={} + offset={} = {}, new_start={}",
                hunk.old_start,
                offset,
                start + 1,
                hunk.new_start
            );
        }

        let mut remove_count = 0;
        let add_lines: Vec<String> = hunk
            .lines
            .iter()
            .filter_map(|l| match l {
                PatchLine::Add(s) => Some(s.clone()),
                _ => None,
            })
            .collect();

        for line in &hunk.lines {
            if matches!(line, PatchLine::Remove(_)) {