ui: name a sample's document after it until saved (#334); "Solve cancelled"

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/engine/src/cmd/file.rs

@@ -106,6 +106,7 @@ fn open_sample(s: &mut Session, p: &Value) -> Result<Value> {
     // A sample just opened has nothing to save: it opens again the same way.
     opened.saved_revision = Some(opened.revision);
     opened.saved_view = opened.view.clone();
+    opened.sample = Some(sample.label);
     s.replace_with(opened);
     let mut reply = summary(s, &[]);
     reply["sample"] = json!(sample.name);

crates/engine/src/lib.rs

@@ -224,6 +224,9 @@ pub struct Session {
     pub journal: Vec<(String, Value)>,
     /// The `.fieldcraft` file the session was opened from or last saved to.
     pub path: Option<String>,
+    /// The sample the session was opened as (`file.sample`), by its label; the document is named
+    /// after it until it is saved under a name of its own.
+    pub sample: Option<&'static str>,
     history: History,
     /// Identifies the current state: it changes with every edit, undo and redo, and comes back
     /// when an undo returns to an earlier state.

crates/ui-egui/src/files.rs

@@ -352,8 +352,12 @@ pub enum Answer {
 }
 
 /// The file name a model is saved under by default.
+/// The document's name: its file's, else the sample it was opened as ("Cantilever (sample)").
 fn model_name(session: &Session) -> String {
-    session.path.as_deref().and_then(|p| Path::new(p).file_stem()).and_then(|s| s.to_str()).map_or_else(|| "Untitled".to_string(), str::to_string)
+    match session.path.as_deref().and_then(|p| Path::new(p).file_stem()).and_then(|s| s.to_str()) {
+        Some(stem) => stem.to_string(),
+        None => session.sample.map_or_else(|| "Untitled".to_string(), |label| format!("{label} (sample)")),
+    }
 }
 
 /// `path` with `ext` added when it has no extension of that name (some pickers leave it off).
@@ -406,7 +410,7 @@ fn spawn(session: Session, command: &'static str, params: Value) -> (Receiver<(B
 }
 
 impl ModelApp {
-    /// The model's name: its file's stem, or "Untitled".
+    /// The model's name: its file's stem, the sample it was opened as, or "Untitled".
     pub fn model_name(&self) -> String {
         model_name(&self.session)
     }
@@ -579,7 +583,8 @@ impl ModelApp {
     pub fn cancel_loading(&mut self) {
         if let Some(l) = self.loading.take() {
             self.queued.clear();
-            self.set_status(format!("Cancelled: {}", l.title), false);
+            let line = if l.title == "Solving" { "Solve cancelled".to_string() } else { format!("{} cancelled", l.title) };
+            self.set_status(line, false);
         }
     }