Function find_rrl_ntm_display_window 

pub(super) fn find_rrl_ntm_display_window(
    bases: &[u8],
    peak_locs: &[u16],
) -> Option<(u16, u16, bool, u16)>

Locate the SNP site in a Sanger read and return the scan-coordinate window to display around it.

Returns Some((start_scan, end_scan, is_reverse_complement, snp_base_idx)) or None if the anchor sequence cannot be found or the window falls outside the trace.

How it works

The rrl SNP of interest sits at a fixed position relative to two flanking anchor sequences (RRL_ANCHOR_L on the left, RRL_ANCHOR_R on the right). The function tries both read orientations:

1. Forward — searches bases for RRL_ANCHOR_L. If found, the SNP position is the base immediately after the anchor. A display window of 9 bases to the left and 10 to the right is converted to scan coordinates via super::scan_window, and is_reverse_complement is set to false.

2. Reverse-complement — searches bases for the reverse complement of RRL_ANCHOR_R. If found, the SNP position is again the base immediately after that match (which corresponds to the SNP on the complementary strand). The left/right margins are swapped (10 left, 9 right) so the displayed window covers the same biological region. is_reverse_complement is set to true.

The forward orientation is tried first; the reverse-complement is only attempted if the forward search fails.