Bundle the first-party Python scripting plugin

plugins/opencad-python/src/selection_cache.rs

@@ -0,0 +1,33 @@
+//! Process-wide cache of the most recently observed selection.
+//!
+//! `HostApi` has no synchronous "give me the current selection" call — only
+//! the best-effort `SelectionChanged` / `SelectionChangedV4` notification.
+//! Naively calling `HostApi::try_recv_notification()` from inside `dispatch`
+//! doesn't work: `ocs_plugin_api::runner`'s own V4 event loop
+//! (`run_v4` in `runner.rs`) drains that queue itself on every iteration,
+//! forwarding each notification to `BuiltinPlugin::on_notification` *before*
+//! a `Dispatch` request ever reaches `dispatch()` — so by the time `dispatch`
+//! runs, the queue is always empty. The only way to observe notifications is
+//! to override `on_notification` and stash what's needed here; `dispatch`
+//! (and the `ocs.selection()` pyfunction) then just reads this cache.
+//!
+//! A plain process-wide static is fine here: one plugin process hosts exactly
+//! one `PythonPlugin`, so this is equivalent to an instance field, but a
+//! static is far simpler to reach from the `#[pymodule]` native functions in
+//! `ocs_module.rs`, which have no path back to the `BuiltinPlugin` instance.
+
+use std::sync::Mutex;
+
+use ocs_plugin_api::host::Handle;
+
+static CACHE: Mutex<Vec<Handle>> = Mutex::new(Vec::new());
+
+pub(crate) fn set(handles: Vec<Handle>) {
+    if let Ok(mut cache) = CACHE.lock() {
+        *cache = handles;
+    }
+}
+
+pub(crate) fn get() -> Vec<Handle> {
+    CACHE.lock().map(|cache| cache.clone()).unwrap_or_default()
+}