pub fn document_signature(doc_json: &str) -> StringExpand description
A STABLE content signature of a document: a sorted-key JSON walk hashed
with the (fixed-key, cross-process-deterministic) std SipHash. The ONE
signature fn, at the ENGINE altitude so app-side and engine-side writers
share one copy: the app’s insert flow (panels::file), the edit-in-place
Finish (panels::assembly_edit::refresh_library_entry) and the
update-components comparison (panels::update_components) all write/compare
a parts-library sourceSignature with THIS function — a freshly inserted,
unchanged part must always compare up-to-date, which a second copy would
break the moment either drifted.
(Distinct from the kernel’s parts_library::stable_json_hash, which is an
in-memory doc_hash for the per-feature fingerprint hook.)