feat: enhance command classification and error handling; improve process checks and credential security

src/model/session_lock.rs

@@ -52,12 +52,34 @@ impl SessionLock {
         let _ = fs::remove_file(&self.path);
     }
 
-    /// Check whether a process with the given PID is currently alive.
+    /// Check whether a process with the given PID is currently alive and
+    /// is actually a zesdex process (not a recycled PID from a different
+    /// program).
     fn is_alive(&self, pid: u32) -> bool {
         // SAFETY: `libc::kill(pid, 0)` does not send a signal; it only checks
         // whether the process exists and the caller has permission to signal
         // it. The integer argument is a PID already validated by `try_lock`.
-        unsafe { libc::kill(pid as i32, 0) == 0 }
+        if unsafe { libc::kill(pid as i32, 0) != 0 } {
+            return false;
+        }
+        // Extra check: verify the PID belongs to a zesdex process via
+        // /proc/<pid>/exe to mitigate the PID-reuse race (a recycled PID
+        // from a different program would answer kill but shouldn't hold
+        // our lock). This is best-effort — /proc may not be available
+        // on all platforms.
+        let proc_exe = std::path::PathBuf::from(format!("/proc/{}/exe", pid));
+        match std::fs::read_link(&proc_exe) {
+            Ok(target) => match std::env::current_exe() {
+                Ok(exe) => {
+                    if target != exe {
+                        return false;
+                    }
+                }
+                Err(_) => { /* cannot resolve own exe, trust kill check */ }
+            },
+            Err(_) => { /* /proc unavailable, trust kill check */ }
+        }
+        true
     }
 }