Warn about missing media when opening a session (#57)

apps/soundcraft-cli/src/main.rs

@@ -76,8 +76,9 @@ fn info(args: &[String]) -> ExitCode {
     let Some(path) = args.first() else { return fail("info FILE") };
     if path.ends_with(".scraft") {
         let mut e = Engine::default();
-        if let Err(err) = soundcraft_engine::io::open_session(&mut e, path) {
-            return fail(err);
+        match soundcraft_engine::io::open_session(&mut e, path) {
+            Ok(missing) => warn_missing(&missing),
+            Err(err) => return fail(err),
         }
         outln!("{}", soundcraft_engine::inspect::session_text(&e));
         return ExitCode::SUCCESS;
@@ -135,10 +136,22 @@ fn convert(args: &[String]) -> ExitCode {
     }
 }
 
+/// One stderr line per media file a session refers to but could not load (the exit code is unchanged).
+fn missing_warnings(missing: &[String]) -> Vec<String> {
+    missing.iter().map(|m| format!("warning: missing media: {m}")).collect()
+}
+
+fn warn_missing(missing: &[String]) {
+    for line in missing_warnings(missing) {
+        eprintln!("{line}");
+    }
+}
+
 fn load_engine(args: &[String]) -> Result<Engine, String> {
     if let Some(p) = arg_value(args, "--in") {
         let mut e = Engine::default();
-        soundcraft_engine::io::open_session(&mut e, &p).map_err(|e| e.to_string())?;
+        let missing = soundcraft_engine::io::open_session(&mut e, &p).map_err(|e| e.to_string())?;
+        warn_missing(&missing);
         Ok(e)
     } else if args.iter().any(|a| a == "--demo" || a == "--sample") {
         Ok(soundcraft_engine::demo::demo_engine())
@@ -336,3 +349,15 @@ fn parity(args: &[String]) -> ExitCode {
     }
     ExitCode::SUCCESS
 }
+
+#[cfg(test)]
+mod tests {
+    use super::missing_warnings;
+
+    #[test]
+    fn missing_media_gets_one_warning_each() {
+        assert!(missing_warnings(&[]).is_empty());
+        let w = missing_warnings(&["a.wav".to_string(), "b.wav: decode failed".to_string()]);
+        assert_eq!(w, vec!["warning: missing media: a.wav", "warning: missing media: b.wav: decode failed"]);
+    }
+}

crates/engine/src/cmd/file.rs

@@ -11,8 +11,8 @@ pub fn specs() -> Vec<CommandSpec> {
         cmd!(noundo "session.new", "New...", ["File"], Some("Cmd+N"), "{name?: 'Untitled', sample_rate?: 48000, bit_depth?: 24, template?: blank|demo}", always, new_session),
         cmd!(noundo "session.open", "Open Session...", ["File"], Some("Cmd+O"), "{path}", always, |e, p| {
             let path = str_param(p, "path").ok_or_else(|| bad("session.open", "`path` required"))?.to_string();
-            crate::io::open_session(e, &path)?;
-            Ok(json!({"name": e.session().name, "tracks": e.session().tracks.len()}))
+            let missing = crate::io::open_session(e, &path)?;
+            Ok(json!({"name": e.session().name, "tracks": e.session().tracks.len(), "missing": missing}))
         }),
         cmd!(noundo "session.close", "Close Session", ["File"], Some("Cmd+Shift+W"), "{}", always, |e, _| { e.replace_session(Session::default()); e.path = None; Ok(json!({})) }),
         cmd!(noundo "session.save", "Save Session", ["File"], Some("Cmd+S"), "{path?}", always, |e, p| {
@@ -270,3 +270,34 @@ fn write_score(e: &mut Engine, p: &Value, id: &str, svg: bool) -> Result<Value>
     let measures = parts.iter().map(|p| p.measures.len()).max().unwrap_or(0);
     Ok(json!({"path": path, "parts": parts.len(), "measures": measures}))
 }
+
+#[cfg(test)]
+mod open_tests {
+    use super::*;
+
+    fn remove_media(dir: &std::path::Path) {
+        for entry in std::fs::read_dir(dir).into_iter().flatten().flatten() {
+            let p = entry.path();
+            if p.is_dir() {
+                remove_media(&p);
+            } else if p.extension().is_some_and(|x| x != "scraft") {
+                let _ = std::fs::remove_file(&p);
+            }
+        }
+    }
+
+    #[test]
+    fn session_open_reports_missing_media() {
+        let mut e = crate::demo::demo_engine();
+        let dir = std::env::temp_dir().join(format!("soundcraft-open-missing-{}", std::process::id()));
+        let path = dir.join("Gone.scraft").to_string_lossy().into_owned();
+        e.execute("session.save_as", &json!({"path": path})).unwrap();
+        let mut ok = Engine::default();
+        assert!(ok.execute("session.open", &json!({"path": path})).unwrap()["missing"].as_array().is_some_and(Vec::is_empty));
+        remove_media(&dir);
+        let mut r = Engine::default();
+        let res = r.execute("session.open", &json!({"path": path})).unwrap();
+        assert!(res["missing"].as_array().is_some_and(|m| !m.is_empty()), "{res}");
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}

docs/mcp.md

@@ -24,7 +24,7 @@ claude mcp add soundcraft -- soundcraft-cli mcp --demo
 | `execute` | Run one command with JSON params. |
 | `batch` | Run several commands in order (`keep_going` optional). |
 | `inspect_session` | Verify work: tracks, clips, mixer, plugins, sends, automation, markers, selection. |
-| `new_session`, `open_session`, `save_session` | Session files (`.scraft`, audio in `Audio Files/`). |
+| `new_session`, `open_session`, `save_session` | Session files (`.scraft`, audio in `Audio Files/`). `open_session` returns `missing`: the media files that could not be loaded (empty when all are found). |
 | `import_audio` | WAV, AIFF, FLAC, MP3, OGG, AAC/M4A, ALAC, CAF onto a new or existing track. |
 | `bounce_mix` | Render to WAV/AIFF/FLAC; returns peak dBFS and integrated LUFS. |
 | `parity` | Feature-parity report. |