feat: enhance subagent context with abort flag and implement tool call timeout

src/model/session.rs

@@ -78,9 +78,20 @@ impl Session {
 
     /// Load a session's metadata by id from `<base_dir>/sessions/<id>/session.json`.
     ///
+    /// Security: the session id is validated to prevent directory traversal
+    /// (e.g. `../../etc/passwd`). Only alphanumeric, hyphens, underscores,
+    /// and dots are allowed — no path separators.
+    ///
     /// Return: the parsed `Session`, or an `io::Error` if the file is
     /// missing or malformed.
     pub fn load(id: &str, base_dir: &Path) -> std::io::Result<Self> {
+        // Reject session ids that contain path separators or parent dir refs
+        if id.contains('/') || id.contains('\\') || id.contains("..") {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidInput,
+                format!("invalid session id '{}': must not contain path separators", id),
+            ));
+        }
         let path = base_dir.join("sessions").join(id).join("session.json");
         let data = std::fs::read_to_string(path)?;
         let session: Session = serde_json::from_str(&data)?;