Function group_entries 

pub fn group_entries(
    entries: &[HistoryEntry],
    named: &[NamedRange],
    cfg: &GroupingConfig,
) -> Vec<HistoryGroup>

Group entries (oldest first, in the producer’s causal order).

Concurrent naming

Two people naming ranges at the same time resolves here, at read time, identically on every peer — the inputs are the document and nothing else.

• The same range, twice. Both writes land on the same document key (derived from the range’s first change), so automerge’s map-conflict rule picks one deterministically; the other stays recoverable in the change graph.
• One range inside another. The inner one becomes a child of the outer, up to MAX_GROUP_DEPTH. Deeper than that, it is not rendered as a group but reappears once an enclosing name is removed.
• Ranges that partly overlap. The earlier-starting range keeps its whole span; the later one is clipped to what’s left — clipping rather than dropping means neither user loses their name to a race.

A named range whose first change is not in entries is skipped: the surface cannot show a band whose contents it does not have.