ocs_doc_api: layer CRUD, per-curve layer assignment, XDATA/XRECORD support, and bulk SetXDataMany

crates/ocs_doc_api/ARCHITECTURE.md

@@ -4,6 +4,12 @@
 `Transport::apply` carries one operation or a read-only query batch to the
 executor. The native adapter binds each request to its existing `HostSession`.
 
+For out-of-process / worker-thread plugins, `doc_api_for_host(host)` constructs a
+`DocApi` backed by `OcsPluginApiIpc`, which sends `PluginRequest::DocApiRequest`
+through the host's `PluginRequestSender` and deserializes
+`PluginResponse::DocApiResponse`. This keeps plugin code free of manual envelope
+serialization while reusing the same executor that the in-process transport uses.
+
 The executor validates inputs and dispatches through `DocApiBackend`. Backends
 must prepare fallible geometry and serialization before changing the document.
 Bulk writes prepare all entities, begin one undo record, apply the prepared
@@ -22,14 +28,18 @@ do not reorder them. The consistency tests verify their bincode discriminants.
 generates the API reference and binding schema. The layout snapshot is curated
 vocabulary, not a reflected binary codec schema.
 
+Layer CRUD is a document-table family, not an entity family. The API carries
+layer properties in the plain-data `LayerInfo` DTO and the host translates them
+to/from `acadrust::tables::Layer`. Layer names are case-insensitive. The host
+rejects duplicate names, deletion of layer "0" or the current layer, and removal
+of a layer that still has entities assigned.
+
+XDATA and XRECORD are serialization roundtrip families: the API carries their
+payloads as plain-data DTOs and the host stores/retrieves them without semantic
+interpretation. XDATA records are keyed by registered application name on any
+entity; XRECORD objects are standalone named dictionaries of group-code/value
+entries. Both preserve exact bytes/values across save and reload.
+
 To extend the API, update the DTO, backend, executor, facade and spec together,
 add a native behavior test, and rebuild the generated reference/schema. New
 backend methods must reject unsupported behavior explicitly.
-
-Extension workflow:
-
-1. Add the operation/query DTO and its name mapping, then update `spec/entities.toml`.
-2. Implement validation, backend preparation, executor dispatch and facade methods.
-3. Preserve each profile's plane and use cadkernel for geometry.
-4. Test native behavior, failed-operation atomicity and the binding transport payload.
-5. Run `cargo test -p ocs_doc_api --all-features` and rebuild the generated snapshots.