Merge pull request #1423 from felixriestra:pr/python-host-model

The bundled `opencad.python` plugin drives OCS through plugin API v7: all
43 canvas entity kinds, the drawing tables, and OCS's own commands run
step by step. RustPython stays in the plugin process — the plugin crate is
outside the workspace with its own lock file, so the application's own
dependencies are unchanged.

Reconciled with the plugin command work that landed as #1425, which the
branch was written before:

- Both added `impl Drop for PluginProcessInteractiveAdapter`, which git
  merges silently into two impls that do not compile. One body now
  cancels the command and then drops it from the runner, in that order: a
  plugin waiting on a step has to be released before the runner forgets
  the command.
- `execute_command` (#1425) and `run_command` (#1423) are both routes from
  a script to the command line, and only the second was guarded. The
  SCRIPTCOMMANDS switch and the denylist are shared now, so neither route
  is the unguarded one.
- `run_command` dispatched with plugin dispatch still enabled, so a script
  naming a plugin command re-entered the plugin that was blocked waiting
  for it. It sets the suppression flag for the length of the dispatch, as
  `execute_command` does.

The denylist read the command as typed, while the dispatcher resolves
aliases: a user-defined `Q` for `QUIT` (ALIASEDIT writes those) walked
past it. It resolves the alias first.

Also: the active-command comparison ran on every message, a mouse move
included, allocating two strings for names that are already `&'static
str`; SCRIPTCOMMANDS' own messages go through the translation macros; and
`docs/.DS_Store` (now ignored) and an unrelated RTF note about constraint
commands are out of the tree.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

crates/ocs_plugin_api/src/ipc/protocol.rs

@@ -17,7 +17,7 @@
 
 use serde::{Deserialize, Serialize};
 
-use crate::host::{CommandSource, CommandStep};
+use crate::host::{CommandSource, CommandStep, HostSettingValue};
 use crate::manifest::ApiVersion;
 use crate::ribbon::owned::{OwnedPluginManifest, OwnedRibbonGroup};
 
@@ -81,6 +81,8 @@ pub enum HostRequest {
         code: String,
         tab_index: usize,
     },
+    /// V7: release an interactive command after completion or cancellation.
+    DropInteractive { command_id: u64 },
 }
 
 /// Responses the plugin runner sends back for `HostRequest`.
@@ -149,6 +151,21 @@ pub enum PluginRequest {
     ModifyLayer(crate::host::LayerConfig),
     /// Run a command on the active document tab's command line (AutoLISP style).
     ExecuteCommand(String),
+    /// Read a host-managed setting without nested command dispatch.
+    GetSystemVariable { name: String },
+    /// Change a host-managed setting without nested command dispatch.
+    SetSystemVariable { name: String, value: HostSettingValue },
+    /// V7: validate and replace existing entities in a single undo step.
+    UpdateEntitiesTransaction { label: String, entities: Vec<EntityType> },
+    /// V7: synchronous selection read/write for the dispatch tab.
+    GetSelection,
+    SetSelection { handles: Vec<Handle> },
+    /// V7 (additive): kernel-backed solid create or transform.
+    SolidOperation { operation: crate::host::SolidOperation },
+    /// V7 (additive): drawing table record create/modify/rename/delete.
+    TableOperation { operation: crate::host::TableOperation },
+    /// V7 (additive): drive an OCS command.
+    RunCommand { request: crate::host::CommandRequest },
 }
 
 /// Responses the host sends back for `PluginRequest`.
@@ -177,6 +194,14 @@ pub enum PluginResponse {
     DocumentPath(Option<std::ffi::OsString>),
     /// Optional entity handle (e.g. from AddLayer).
     OptHandle(Option<Handle>),
+    SystemVariable(Option<HostSettingValue>),
+    SystemVariableResult(Result<HostSettingValue, String>),
+    EntityTransactionResult(Result<(), String>),
+    Selection(Vec<Handle>),
+    SelectionResult(Result<(), String>),
+    SolidResult(Result<Handle, String>),
+    TableResult(Result<Handle, String>),
+    CommandResult(Result<crate::host::CommandOutcome, String>),
 }
 
 /// Messages sent from the host to the plugin runner.