Diagnostics: pre-launch readiness warning + named friend logs (join.log)

Two additions after the live-session troubleshooting:

1. LAUNCH-SHORT is now VISIBLE (btconsole).  Pressing LAUNCH with an
   empty roster seat previously did NOTHING (eggs_done_at only sets when
   ALL seats ACK, so the manual-launch arming silently no-op'd -- the
   'I pressed launch and nothing happened' confusion).  Now the relay
   logs 'LAUNCH pressed but NOT all seats are filled' + a per-seat
   readiness line + a WARNING naming the empty seat(s) and the fix
   (reduce the roster).  When all seats DO fill it auto-arms (launch
   request persists).  Verified: 2/3 filled -> clear warning naming
   seat3.

2. Friend logs are now retrievable (btoperator exporter).  join.bat /
   join_lan.bat set BT_LOG=join.log and their exit message tells the
   player to send content\join.log to the operator if the game closed
   unexpectedly -- closes the friend-side-crash blind spot (their log
   was the generic btl4.log, un-named, easy to miss).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

players/join.bat

@@ -2,10 +2,12 @@
 rem BT411 -- join 107.202.218.169's game (internet).  Your seat/mech
 rem is assigned automatically by the operator console.
 set BT_RELAY=107.202.218.169:1500
+set BT_LOG=join.log
 cd /d %~dp0content
 ..\build\Release\btl4.exe -egg OPERATOR.EGG -net 1501
 echo.
-echo The game has exited.  If you did NOT quit on purpose,
-echo the session may not be running yet or the server was
-echo unreachable -- check with the operator and try again.
+echo The game has exited.  If you did NOT quit on purpose
+echo (crash, or it never connected), send the operator the
+echo file  content\join.log  so they can see what happened.
+echo Otherwise the session may not be up yet -- try again.
 pause

players/join_lan.bat

@@ -3,10 +3,12 @@ rem BT411 -- join the game from the operator's OWN
 rem network (LAN) -- finds the console automatically.
 rem Joining over the INTERNET?  Use join.bat instead.
 set BT_RELAY=auto
+set BT_LOG=join.log
 cd /d %~dp0content
 ..\build\Release\btl4.exe -egg OPERATOR.EGG -net 1501
 echo.
-echo The game has exited.  If you did NOT quit on purpose,
-echo the session may not be running yet or the server was
-echo unreachable -- check with the operator and try again.
+echo The game has exited.  If you did NOT quit on purpose
+echo (crash, or it never connected), send the operator the
+echo file  content\join.log  so they can see what happened.
+echo Otherwise the session may not be up yet -- try again.
 pause

tools/btconsole.py

@@ -284,6 +284,7 @@ class Relay:
         self.manual_launch = manual_launch
         self._reserved_tags = set(reserved_tags or ())
         self.launch_requested = False            # set by the operator (stdin)
+        self._launch_blocked_warned = False      # warned once about empty seats
         self.stop_requested = False              # operator 'stop' (End Mission)
         self.mission_length = parse_egg_mission_length(egg_path)
         self.mission_started_at = None           # set when RunMission #2 fires
@@ -463,18 +464,46 @@ class Relay:
         if conn in self.console_conns:
             self.console_conns.remove(conn)
 
+    def _log_launch_readiness(self):
+        # PRE-LAUNCH READINESS (2026-07-18): make the "launching short" footgun
+        # VISIBLE.  A roster seat with no registered pod means the mission will
+        # STALL -- every pod waits on that empty seat's connection and the
+        # All-connections-completed gate never fires.  Log filled vs empty
+        # seats so the operator sees it BEFORE the confusion.
+        filled, empty = [], []
+        for i, tag in enumerate(self.roster):
+            host_id = FIRST_GAME_HOST_ID + i
+            (filled if host_id in self.by_host else empty).append(
+                f"seat{i + 1}({tag})")
+        print(f"[relay] LAUNCH readiness: {len(filled)}/{len(self.roster)} "
+              f"seats filled -- {', '.join(filled) or 'NONE'}", flush=True)
+        if empty:
+            print(f"[relay] *** WARNING: {len(empty)} EMPTY seat(s): "
+                  f"{', '.join(empty)} -- the mission will STALL (every pod "
+                  f"waits on the empty seat).  Stop, reduce the roster to the "
+                  f"players present, and re-launch.", flush=True)
+
     def _tick_launch(self):
         # Manual mode: the operator's 'launch' arms the timer, still honouring
         # the settle window (pods must reach WaitingForLaunch or the handler
         # Fail()s -- the same reason the auto timer waits).
         if (self.manual_launch and self.launch_requested
-                and self.launch_at is None and self.eggs_done_at is not None
-                and self.launches_sent == 0):
-            self.launch_at = max(time.time(),
-                                 self.eggs_done_at + LAUNCH_SETTLE_SECONDS)
-            wait = max(0.0, self.launch_at - time.time())
-            print(f"[relay] operator LAUNCH received; firing in {wait:.0f}s",
-                  flush=True)
+                and self.launch_at is None and self.launches_sent == 0):
+            if self.eggs_done_at is not None:
+                self.launch_at = max(time.time(),
+                                     self.eggs_done_at + LAUNCH_SETTLE_SECONDS)
+                wait = max(0.0, self.launch_at - time.time())
+                print(f"[relay] operator LAUNCH received; firing in "
+                      f"{wait:.0f}s", flush=True)
+                self._log_launch_readiness()
+            elif not self._launch_blocked_warned:
+                # Operator pressed LAUNCH but the gate is NOT ready (not every
+                # roster seat has ACKed its egg) -- previously this did NOTHING
+                # visible ("I pressed launch and nothing happened").  Say WHY.
+                self._launch_blocked_warned = True
+                print("[relay] LAUNCH pressed but NOT all seats are filled:",
+                      flush=True)
+                self._log_launch_readiness()
         if self.launch_at is None or self.launches_sent >= 2:
             return
         if time.time() < self.launch_at:

tools/btoperator.py

@@ -756,15 +756,17 @@ class Operator(QMainWindow):
         # file -- who flies which mech is whoever sits down first, exactly
         # like walking up to a pod.
         tail = ("echo.\n"
-                "echo The game has exited.  If you did NOT quit on purpose,\n"
-                "echo the session may not be running yet or the server was\n"
-                "echo unreachable -- check with the operator and try again.\n"
+                "echo The game has exited.  If you did NOT quit on purpose\n"
+                "echo (crash, or it never connected), send the operator the\n"
+                "echo file  content\\join.log  so they can see what happened.\n"
+                "echo Otherwise the session may not be up yet -- try again.\n"
                 "pause\n")
         with open(os.path.join(out_dir, "join.bat"), "w", newline="\r\n") as f:
             f.write("@echo off\n"
                     "rem BT411 -- join %s's game (internet).  Your seat/mech\n"
                     "rem is assigned automatically by the operator console.\n"
                     "set BT_RELAY=%s:%d\n"
+                    "set BT_LOG=join.log\n"
                     "cd /d %%~dp0content\n"
                     "..\\build\\Release\\btl4.exe -egg %s -net 1501\n"
                     % (host, host, self.f_port.value(), egg_name) + tail)
@@ -775,6 +777,7 @@ class Operator(QMainWindow):
                     "rem network (LAN) -- finds the console automatically.\n"
                     "rem Joining over the INTERNET?  Use join.bat instead.\n"
                     "set BT_RELAY=auto\n"
+                    "set BT_LOG=join.log\n"
                     "cd /d %%~dp0content\n"
                     "..\\build\\Release\\btl4.exe -egg %s -net 1501\n"
                     % egg_name + tail)