Merge PR #8 fixes 1 and 2 into experimental

From 0x1f6's robustness PR: survive a malformed control datagram (adapted
to wrap experimental's textfield command too) and plan a layout when the
rows setting exceeds what the screens fill. The PR's third commit, the
volume-key swap rollback, is left out: rolling back a partial remap leaves
every real volume key exposed to gamescope instead of some, and on restore
it turns already-restored keys back into stand-ins.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

input/input-relay.py

@@ -910,6 +910,10 @@ def main():
                 return
             words = data.decode(errors="replace").split()
             cmd = words[0] if words else ""
+            # One malformed datagram must not end the relay: it would drop every grab,
+            # including the volume keys that keep gamescope from aborting. The control
+            # socket is an abstract socket, so any local process can send to it.
+            try:
                 if cmd == "keyboard":
                     # From ft-screens (unbound, no reply): where typing goes, repeated every second.
                     desktop = len(words) > 1 and words[1] == "desktop"
@@ -952,6 +956,8 @@ def main():
                     reply(addr, {"t": "vrcapture", "seconds": seconds})
                 else:
                     reply(addr, {"t": "error", "error": f"unknown command {cmd!r}"})
+            except Exception as e:
+                log(f"bad control datagram {data!r}: {e!r}")
 
     def broadcast(node, etype, code, value, now):
         if not watchers or not node.candidate:

layout/ft_layout.py

@@ -318,6 +318,10 @@ def plan(layout, count, panel_size=None):
     p = layout["preset"]
     rows = max(1, min(int(p.get("rows", 1)), count))
     cols = math.ceil(count / rows)
+    # A row setting above what the screens fill leaves empty grid rows (4 screens,
+    # 3 rows -> cols 2 -> a third row with nothing in it), and max() over an empty
+    # row crashes plan(). Trim rows to what the screens actually fill.
+    rows = max(1, math.ceil(count / cols))
     d = max(0.3, float(p.get("distance", 2.0)))
     gap = max(0.0, float(p.get("gap", 0.05)))
     height = float(p.get("height", 0.0))