pub fn diff(a: &Tree, b: &Tree) -> Vec<DeltaOp>Expand description
Compute a delta that transforms a into b. apply(a, diff(a, b))
equals b (modulo position resolution; see the property tests).
The diff is structurally faithful but not optimized: it never emits
DeltaOp::Replace for whole-subtree collapse. The 40%-edit-
distance threshold lives at the daemon level (M4) where ref churn
is observable across many snapshots.