Class ZoneApi

Nearest Zone-class template ancestor of zone, or null at universe-root (or when zone has no templatePath, e.g., a fixture built via makeStuff without a path stamp). Skips non-Zone path segments. Lazy-clones the ancestor via StuffApi.singleton (cache-or-clone; subsequent calls are O(1)).

The orchestration step Zone.lookupAncestorField (the polymorphic field-inheritance hook in lib/zone/Zone.ts) delegates to this helper. Lives here, not on Zone, because the walk is pure plumbing — no override seam needed, no Stuff subclass should reshape it.

Does the class at classPath extend Zone? Folder classes (the folder/leaf invariant's "may have descendants" set) are exactly the Zone subclasses; this predicate is what Template.findByPath and TemplateApi.validateFolderLeaf* consult.

Result is cached per classPath. Returns false when the class fails to import or has no prototype chain (e.g. a typoed path) — the caller's path validation surfaces those errors separately.

Does the class at classPath extend SpatialZone? The strict subset of folder classes that stamp Stuff.zone. Non-spatial Zones (Clade) return false here even though isFolderClass returns true for them.

Resolve the nearest spatial zone for a template path.

Walks ancestor paths from nearest to root; returns the singleton SpatialZone at the first ancestor whose template's class extends SpatialZone. Non-spatial zone ancestors (Clades, future permission/rule scopes) are skipped — they're folders for the template-tree invariant, but not the spatial zone for the descendant.

Returns null when:

• The template at templatePath is itself a spatial Zone (a zone isn't inside itself).
• No ancestor resolves to a spatial Zone template.

Calls StuffApi.singleton(ancestor) so the second resolution for the same zone path is an O(1) cache hit; first resolution clones.