MCP: an agent's folders hold for file loads through the app and for a design's font files (#1112)

doc.open and the STEP/mesh imports run on the file loader's worker with the request's path scope, and a font named by file path in a design is checked against the scope before it is read.

crates/ui-egui/src/file_load.rs

@@ -37,11 +37,13 @@ pub struct Request {
     pub kind: Kind,
     /// A control-channel caller waiting for the command's reply.
     pub reply: Option<Sender<ControlResponse>>,
+    /// The folders that caller's agent may use: the worker reads the file inside them.
+    pub scope: Option<solidcraft_engine::io::vfs::PathScope>,
 }
 
 impl Request {
     pub fn new(path: &str, kind: Kind) -> Self {
-        Request { path: path.into(), kind, reply: None }
+        Request { path: path.into(), kind, reply: None, scope: None }
     }
     fn insert(&self) -> bool {
         self.kind == Kind::Insert
@@ -180,7 +182,14 @@ pub fn control(app: &mut SolveApp, req: crate::control::ControlRequest) -> Optio
         _ => return Some(req),
     };
     let Some(path) = req.params.get("params").and_then(|p| p.get("path")).and_then(Value::as_str) else { return Some(req) };
-    let _ = begin_request(app, Request { path: path.into(), kind, reply: Some(req.reply.clone()) });
+    let scope = match crate::control::request_scope(app, &req.params) {
+        Ok(scope) => scope,
+        Err(e) => {
+            let _ = req.reply.send(json!({"ok": false, "error": e}));
+            return None;
+        }
+    };
+    let _ = begin_request(app, Request { path: path.into(), kind, reply: Some(req.reply.clone()), scope });
     None
 }
 
@@ -238,6 +247,7 @@ fn start(app: &mut SolveApp) {
     let (tx, rx) = std::sync::mpsc::channel();
     let (preview_tx, preview_rx) = std::sync::mpsc::channel();
     let (command, params) = request.command();
+    let scope = request.scope.clone();
     let thumbnail = request.kind == Kind::Open;
     let spawned = std::thread::Builder::new().name("file-load".into()).spawn(move || {
         let preview_began = std::time::Instant::now();
@@ -256,9 +266,10 @@ fn start(app: &mut SolveApp) {
                 }
             }));
         }
-        let result =
-            std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| compute(scratch, command, &params, thumbnail, &worker_phase, &worker_progress)))
-                .unwrap_or_else(|_| Err("the file operation failed; the current design is unchanged".into()));
+        let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+            compute(scratch, command, &params, scope, thumbnail, &worker_phase, &worker_progress)
+        }))
+        .unwrap_or_else(|_| Err("the file operation failed; the current design is unchanged".into()));
         let _ = tx.send(result);
     });
     match spawned {
@@ -364,15 +375,26 @@ fn preview_work_fits(scene: &solidcraft_engine::render::Scene, camera: &solidcra
 }
 
 #[cfg(not(target_arch = "wasm32"))]
-fn compute(mut session: Session, command: &str, params: &Value, thumbnail: bool, phase: &AtomicU8, progress: &Arc<Progress>) -> Job {
+fn compute(
+    mut session: Session,
+    command: &str,
+    params: &Value,
+    scope: Option<solidcraft_engine::io::vfs::PathScope>,
+    thumbnail: bool,
+    phase: &AtomicU8,
+    progress: &Arc<Progress>,
+) -> Job {
     let profile = solidcraft_engine::geom::env::var_os("PROFILE_OPEN").is_some();
     let began = std::time::Instant::now();
     let cancelled = || Err("file operation cancelled".to_string());
     if progress.is_cancelled() {
         return cancelled();
     }
-    // The timeline's rebuild reports each feature and stops at the next one after Cancel.
-    let result = solidcraft_engine::doc::progress::watch(progress.clone(), || session.execute(command, params)).map_err(|e| e.to_string())?;
+    // The timeline's rebuild reports each feature and stops at the next one after Cancel. An
+    // agent's scope is per thread, so it is set again here.
+    let result =
+        solidcraft_engine::io::vfs::scoped(scope, || solidcraft_engine::doc::progress::watch(progress.clone(), || session.execute(command, params)))
+            .map_err(|e| e.to_string())?;
     if progress.is_cancelled() {
         return cancelled();
     }