JsonTraversal

.at(i) sugar — extend the suffix by an array index.

.field(_.x) sugar — extend the suffix by a named field.

.fields(_.a, _.b, ...) — focus a NamedTuple per element.

Read every focus. String input is parsed first; a prefix-walk miss (or non-array terminal) is Ior.Left(chain), per-element failures accumulate — elements that fail drop out of the Vector while their failures join the chain (Ior.Both).

Silent read — prefix miss yields Vector.empty; undecodable elements are dropped.

Dynamic field sugar — traversal.name lowers to traversal.field(_.name). Compile-time checked against A's case fields; codecs for the field type are summoned at the call site.

Decode each focus, apply f, re-encode in place. String input is parsed first; failures accumulate as Chain[JsonFailure], with the input Json preserved on the Ior.Both side.

Silent modify — any parse / navigation / decode failure passes the input through unchanged (an unparseable String becomes Json.Null first).

Replace each focus with the encoding of a. Same parse / failure-accumulation behaviour as modify.

Silent place — input pass-through on any failure.

place from a foreign source: replace each focus with the encoding of f(c).

Silent transfer — input pass-through on any failure.

Rewrite the raw Json at each focus — no decode of the focus, so f sees (and must return) plain Json. Same parse / failure-accumulation behaviour as modify.

Silent transform — input pass-through on any failure.