zed-industries/zed · error

relative marker maps before first marker

Error message

relative marker maps before first marker

What it means

In the v0317 relative-marker scheme, the cursor's anchor block index plus the model-supplied negative delta resolved to an index before the first marker (below zero), so the start boundary would fall outside the editable region.

Source

Thrown at crates/zeta_prompt/src/multi_region.rs:841

            .context("end marker number out of range")?;
        Ok((start_byte, end_byte))
    })
}

pub fn apply_marker_span_v0317(
    old_editable: &str,
    output: &str,
    cursor_offset_in_old: Option<usize>,
) -> Result<String> {
    let tags = collect_relative_marker_tags(output);
    let marker_offsets = compute_marker_offsets(old_editable);
    let anchor_idx = cursor_block_index(cursor_offset_in_old, &marker_offsets);

    apply_marker_span_impl(old_editable, &tags, output, |start_delta, end_delta| {
        let start_idx_signed = anchor_idx as isize + start_delta;
        let end_idx_signed = anchor_idx as isize + end_delta;
        if start_idx_signed < 0 || end_idx_signed < 0 {
            return Err(anyhow!("relative marker maps before first marker"));
        }
        let start_idx = usize::try_from(start_idx_signed).context("invalid start marker index")?;
        let end_idx = usize::try_from(end_idx_signed).context("invalid end marker index")?;
        let start_byte = *marker_offsets
            .get(start_idx)
            .context("start marker number out of range")?;
        let end_byte = *marker_offsets
            .get(end_idx)
            .context("end marker number out of range")?;
        Ok((start_byte, end_byte))
    })
}

pub fn apply_marker_span_v0318(old_editable: &str, output: &str) -> Result<String> {
    let tags = collect_marker_tags(output);

    if tags.len() >= 2 {
        let start_num = tags[0].value;

View on GitHub (pinned to f4178619ac)

Solutions

1. Clamp the resolved index to the first marker instead of erroring, if the intended span is the region start
2. Reject the output and re-prompt, since the relative offset is inconsistent with the cursor anchor
3. Ensure the cursor offset passed in actually lies inside the editable region's marker blocks

When it happens

Trigger: Thrown at crates/zeta_prompt/src/multi_region.rs:841 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/a68951adc68bcf79. Report an issue: GitHub.