Add host-authoritative world-state sync

Implement host-authoritative time/weather sync across server and clients. Adds a new worldState packet (and worldStateHost for host assignment) and server-side host tracking/reassignment to the lowest remaining playerId when the host disconnects. Plugin-side changes introduce F4T::WorldStateSync (new header + implementation), polling/apply hooks in the game-thread main loop, and Networking support to send/receive/parse worldState/worldStateHost packets. The server validates host-only sends, relays worldState to peers, broadcasts worldStateHost on host handoff, and augments logging/stats. Protocol and documentation files updated (protocol/world-state.md, docs/*) and server/fake_client.py extended to track/print host world-state snapshots.

protocol/README.md

@@ -8,6 +8,7 @@ The first protocol should be simple and focused on player transform sync.
 
 - Welcome packet
 - Transform packet
+- World state packet (host time and weather) — see [`world-state.md`](world-state.md)
 - Disconnect packet
 
 ## Future Packet Types

protocol/message-types.md

@@ -9,6 +9,8 @@ These message types are currently implemented:
 ```text
 welcome
 transform
+worldState
+worldStateHost
 disconnect
 ```
 
@@ -17,11 +19,16 @@ Current behavior:
 - `welcome` is sent by the server after assigning a `playerId`.
 - `transform` is sent by the Fallout 4 plugin, processed by the server, and
   broadcast to other connected clients.
+- `worldState` is sent by the current world-state host, validated by the
+  server, and broadcast to other connected clients.
+- `worldStateHost` is sent in `welcome` and when the host disconnects to
+  reassign host to the lowest remaining `playerId`.
 - `disconnect` is sent by the server when a client disconnects.
 
 The Fallout 4 plugin sends transform packets and receives `welcome`,
-`transform`, and `disconnect` packets. Received transforms are stored as plain
-remote-player state only.
+`transform`, `worldState`, and `disconnect` packets. Received transforms are
+stored as plain remote-player state. Non-host clients apply received world state
+on the game thread.
 
 ## Current Receivers
 
@@ -30,11 +37,14 @@ The Fallout 4 plugin and `server/fake_client.py` currently receive:
 ```text
 welcome
 transform
+worldState
+worldStateHost
 disconnect
 ```
 
 The plugin and fake client store broadcast transform packets in in-memory remote
-player state tables and remove entries when disconnect packets arrive.
+player state tables and remove entries when disconnect packets arrive. The fake
+client also tracks the latest host world-state snapshot.
 
 ## Planned Later
 

protocol/world-state.md

@@ -0,0 +1,77 @@
+# World State Packet
+
+Host-authoritative time and weather sync for the Commonwealth Online prototype.
+
+## Authority
+
+- The server tracks a `worldStateHostPlayerId` for the session.
+- The first connected client becomes host. When the host disconnects, the server
+  reassigns host to the lowest remaining `playerId` and broadcasts `worldStateHost`.
+- Only the current host sends `worldState` packets.
+- The Python relay validates the sender and broadcasts to all other clients.
+
+Promoted hosts keep their already-synced local time and weather; reassignment should
+not change world state for remaining clients.
+
+## worldStateHost Packet
+
+Sent in `welcome` (initial host) and broadcast when the host disconnects:
+
+```json
+{
+  "type": "worldStateHost",
+  "worldStateHostPlayerId": 2,
+  "serverTime": 1780212128.301
+}
+```
+
+| Field | Type | Required | Description |
+|-------|------|----------|-------------|
+| `type` | string | yes | Must be `"worldStateHost"` |
+| `worldStateHostPlayerId` | integer | yes | Connected player ID that is now world-state host |
+| `serverTime` | number (double) | no | Relay timestamp |
+
+The `welcome` packet also includes optional `worldStateHostPlayerId` so new joiners
+know the current host immediately.
+
+## Packet Format
+
+```json
+{
+  "type": "worldState",
+  "playerId": 1,
+  "gameHour": 14.25,
+  "gameDaysPassed": 12.5,
+  "weatherFormId": "00123456",
+  "clientTime": 1780212128.301,
+  "serverTime": 1780212128.301
+}
+```
+
+## Field Definitions
+
+| Field | Type | Required | Description |
+|-------|------|----------|-------------|
+| `type` | string | yes | Must be `"worldState"` |
+| `playerId` | integer | yes (server) | Injected by server; identifies the sending host |
+| `gameHour` | number (float) | yes | In-game hour of day, `0.0`–`24.0` |
+| `gameDaysPassed` | number (float) | yes | In-game days passed global |
+| `weatherFormId` | string | no | 8-character hex `TESWeather` form ID; omitted or `""` when host is indoors |
+| `clientTime` | number (double) | no | Sender Unix epoch seconds |
+| `serverTime` | number (double) | no | Relay timestamp added by server |
+
+## Send Cadence (Host)
+
+- About 1 Hz heartbeat while connected
+- Immediate send when `weatherFormId` changes
+- Immediate send when `gameHour` or `gameDaysPassed` jumps beyond a small threshold (wait, sleep, console time changes)
+
+## Client Apply Rules
+
+- **Time:** non-host clients snap local calendar globals when host values differ beyond threshold.
+- **Weather:** non-host clients apply forced weather only when the local player is in an exterior cell.
+- Missing optional fields use safe defaults on receive.
+
+## Backward Compatibility
+
+Older clients that do not send or parse `worldState` continue to work. Transform sync is unchanged.

protocol/world-sync.md

@@ -1,9 +1,17 @@
 # World Sync
 
-World synchronization is a long-term problem and is not part of the first prototype.
-
 Fallout 4 assumes a single player owns the world state. Multiplayer requires deciding which client or server controls each piece of world state.
 
+## Implemented (MVP)
+
+Host-authoritative time and weather sync is implemented via the `worldState`
+packet. See [`world-state.md`](world-state.md) for the field spec.
+
+- Host: tracked by `worldStateHostPlayerId` (first connected client; reassigned to lowest remaining `playerId` on host disconnect)
+- Synced fields: `gameHour`, `gameDaysPassed`, optional `weatherFormId`
+- Weather apply: exterior cells only on non-host clients
+- Server: pass-through relay with host-only send guard
+
 ## World State Examples
 
 World state can include: