Co-Op Multiplayer: Up to 4 players can now work the same facility together. Each player keeps fully independent progression - own ore/ingot inventory, upgrades, prestige, weapons, save file - while sharing the world itself: hangout space, base expansions, and NPC crew stay shared. Player spawning runs on s&box's built-in networking.

Per-World Co-Op Saves: Co-op progress is stored separately from single-player AND separately for every host you play with (`<hostSteamId>-co-op.dat`). Joining a friend resumes your progress in that friend's world; hosting resumes your own. Progress in one friend's world is never affected by another's. Any pre-existing single shared co-op save is migrated into the first world that needs one, with the original kept as a `.migrated` backup.

Co-Op Facilities List: The co-op menu lists every world you have progress in - host name, time worked, and ingots banked - so it's clear which save each action will open. CONTINUE SHIFT now only appears when the world you would host actually has a save, instead of appearing because any co-op save existed anywhere.

Fresh Shift Propagation: When the host starts a NEW shift, joining players start clean in that world too (their progress in other worlds is untouched). Joining resolves the host's choice instantly rather than pausing on join.

Public Lobby Browser: JOIN A SHIFT lists open co-op sessions and lets you join one directly from the main menu - no invite or connect string needed.

Proper First-Person Tool Models: Every tool - Hammer, Pickaxe, Gold Pickaxe, Clay Pickaxe, Smelter's Pickaxe, Sledgehammer, Shockwave Hammer - now shows a real held first-person model (actual gripping hands, tuned per tool) instead of nothing or a disconnected floating prop.

Visible Swinging: Other players see you actually swing your tool when mining, instead of watching you stand motionless while ore breaks.

Synced Radio & Extraction Progress: The courtyard/vault radios and the TIER progress badge update correctly for every connected player.

Host Admin Panel: A new ADMIN tab (host-only, visible while a session is active) shows connected players with avatars and lets the host kick anyone; a session card tracks player/worker counts, session time, current tier, and host name; and server controls can clear all dropped ore/ingots or force-respawn every ore node, with an activity log tracking recent admin actions.