fix: the server's own folders under a short-named temp path are expanded, not refused (#1055)

On Windows the temporary folder often has an 8.3 short name, which the path scope refuses. vfs::long_names spells folders SolidCraft derives from the environment with long names, and the MCP scratch folder and the recovery folder use it, so screenshot without a path and the recovery commands work there again.

crates/engine/src/cmd/motion_tests.rs

@@ -130,7 +130,7 @@ fn motion_study_plays_and_exports() {
     // The B occurrence's origin moves by the slider value (it starts at 0 offset with value 0 at 10 mm… so 10 → −5).
     assert!((bx(&rows[1]) - bx(&rows[0]) + 3.75).abs() < 1e-6, "{e}");
     assert!(rows[4]["stopped_by_contact"].is_object());
-    let dir = std::env::temp_dir().join(format!("solidcraft-motion-{}", std::process::id()));
+    let dir = solidcraft_io::vfs::temp_dir().join(format!("solidcraft-motion-{}", std::process::id()));
     std::fs::create_dir_all(&dir).unwrap();
     let csv = dir.join("push.csv");
     run(&mut s, "motion.export", json!({"study": "Push", "samples": 3, "path": csv.to_string_lossy()}));

crates/engine/src/cmd/urdf_tests.rs

@@ -96,7 +96,7 @@ fn assert_fk(m: &UrdfModel, s: &Session, what: &str) {
 }
 
 fn temp(tag: &str) -> PathBuf {
-    let d = std::env::temp_dir().join(format!("solidcraft-urdf-{tag}-{}", std::process::id()));
+    let d = solidcraft_io::vfs::temp_dir().join(format!("solidcraft-urdf-{tag}-{}", std::process::id()));
     let _ = std::fs::remove_dir_all(&d);
     let _ = std::fs::create_dir_all(&d);
     d

crates/engine/src/recovery.rs

@@ -18,13 +18,16 @@ use solidcraft_doc::Document;
 use crate::{EngineError, Result, Session};
 
 /// The recovery folder: `SOLIDCRAFT_RECOVERY_DIR`, else the platform's per-user data folder.
+/// Spelled with long names (`vfs::long_names`): an agent's commands reach it by this path, and
+/// short (8.3) names are refused there.
 pub fn default_dir() -> Option<PathBuf> {
+    use solidcraft_io::vfs::long_names;
     // Tests never touch the user's real recovery folder.
     if cfg!(test) {
-        return Some(std::env::temp_dir().join(format!("solidcraft-test-recovery-{}", std::process::id())));
+        return Some(solidcraft_io::vfs::temp_dir().join(format!("solidcraft-test-recovery-{}", std::process::id())));
     }
     if let Some(d) = solidcraft_geom::env::var_os("RECOVERY_DIR").filter(|d| !d.is_empty()) {
-        return Some(PathBuf::from(d));
+        return Some(long_names(Path::new(&d)));
     }
     let env = |k: &str| std::env::var_os(k).filter(|d| !d.is_empty()).map(PathBuf::from);
     let root = if cfg!(windows) {
@@ -34,7 +37,7 @@ pub fn default_dir() -> Option<PathBuf> {
     } else {
         env("XDG_DATA_HOME").or_else(|| env("HOME").map(|h| h.join(".local/share")))?
     };
-    let (dir, legacy) = dirs_under(&root, cfg!(windows) || cfg!(target_os = "macos"));
+    let (dir, legacy) = dirs_under(&long_names(&root), cfg!(windows) || cfg!(target_os = "macos"));
     // Compatibility shim (docs/compatibility.md): autosaves made before the rename (or, in the
     // Flatpak sandbox, under the old app id) are copied to the new folder on first launch; the
     // old folder is left as it was.

crates/engine/src/tests/path_scope.rs

@@ -8,7 +8,7 @@ use crate::*;
 
 #[test]
 fn file_commands_stay_inside_the_agents_folders() {
-    let base = std::env::temp_dir().join(format!("solidcraft-path-scope-{}", std::process::id()));
+    let base = solidcraft_io::vfs::temp_dir().join(format!("solidcraft-path-scope-{}", std::process::id()));
     let _ = std::fs::remove_dir_all(&base);
     let (root, out) = (base.join("root"), base.join("out"));
     std::fs::create_dir_all(&root).unwrap();