Guard dashboard help panel writes to avoid curses overflow

src/reactor_sim/dashboard.py

@@ -457,18 +457,32 @@ class ReactorDashboard:
         self._draw_health_bars(right_win, right_y)
 
     def _draw_help_panel(self, win: "curses._CursesWindow") -> None:
+        def _add_safe(row: int, col: int, text: str, attr: int = 0) -> bool:
+            max_y, max_x = win.getmaxyx()
+            if row >= max_y - 1 or col >= max_x - 1:
+                return False
+            clipped = text[: max(0, max_x - col - 1)]
+            try:
+                win.addstr(row, col, clipped, attr)
+            except curses.error:
+                return False
+            return True
+
         win.erase()
         win.box()
-        win.addstr(0, 2, " Controls ", curses.color_pair(1) | curses.A_BOLD)
+        _add_safe(0, 2, " Controls ", curses.color_pair(1) | curses.A_BOLD)
         y = 2
         for title, entries in self.help_sections:
-            win.addstr(y, 2, title, curses.color_pair(1) | curses.A_BOLD)
+            if not _add_safe(y, 2, title, curses.color_pair(1) | curses.A_BOLD):
+                return
             y += 1
             for entry in entries:
-                win.addstr(y, 4, f"{entry.key:<8} {entry.description}")
+                if not _add_safe(y, 4, f"{entry.key:<8} {entry.description}"):
+                    return
                 y += 1
             y += 1
-        win.addstr(y, 2, "Tips:", curses.color_pair(2) | curses.A_BOLD)
+        if not _add_safe(y, 2, "Tips:", curses.color_pair(2) | curses.A_BOLD):
+            return
         tips = [
             "Start pumps before withdrawing rods.",
             "Bring turbine and consumer online after thermal stabilization.",
@@ -478,7 +492,8 @@ class ReactorDashboard:
             "Watch component health to avoid automatic trips.",
         ]
         for idx, tip in enumerate(tips, start=y + 2):
-            win.addstr(idx, 4, f"- {tip}")
+            if not _add_safe(idx, 4, f"- {tip}"):
+                break
 
     def _draw_status_panel(self, win: "curses._CursesWindow", state: PlantState) -> None:
         win.erase()