- Change `rope_tell()` return type from Option<usize> to usize, always returning cursor's absolute position (offset if unmoved).
- Update all call sites to remove `.unwrap_or(...)` around `rope_tell()`.
- Add new method `<Rope>::truncate(pos)`, replacing `split_off(...).map(|_| ())`.
- Refactor FASTA/FASTQ normalizers to use a single mutable write cursor (`wc`) and document the protocol.
- Simplify `end_segment()` logic: commit segment with 0x00 if length ≥ k, else reset.
- Improve documentation for write-cursor protocol and rope truncation semantics.
- Introduce SeekMode::Rope for absolute rope-index positioning
- Add CursorState.offset field to support local coordinate systems per cursor
- Implement ForwardCursor.cursor() and BackwardCursor(cursor()) to create sub-cursors with independent offsets
- Update tell(), get(i), set i, len() to use local coordinates (relative offset)
- Add rope_tell(), reset()—deprecate old absolute behavior in favor of offset-aware API
- Add comprehensive tests for sub-cursor semantics, including write/reset and bounds checking
Eric Coissac