Docs: Add documentation for fold command

documents/docs/networking/commands/protocol-document.md

@@ -64,6 +64,7 @@ This document describes the protocol for client-server communication in our appl
     - [Example Response](#example-response)
   - [RAISE command](#raise-command)
   - [CALL command](#call-command)
+  - [FOLD command](#fold-command)
   - [BET command](#bet-command)
   - [SEND_MESSAGE command](#send_message-command)
     - [Required pre-execution checks](#required-pre-execution-checks)
@@ -835,6 +836,222 @@ END
 END
 ```
 
+## FOLD command
+
+The `FOLD` command lets the currently logged-in player leave the current hand (fold) in the ongoing game for their lobby.
+
+### Required pre-execution checks
+
+- [`UserLoggedInCheck`](#userloggedincheck)
+
+### Request Parameters
+
+| Parameter Name | Type | Optional | Description |
+| :------------- | :--- | :------: | :---------- |
+| `GAME_ID` | `int` | yes | Numeric id of the lobby/game to target. If omitted the server resolves the lobby by the requesting session's user. |
+
+### Implementation notes
+
+- Parser: `PlayerFoldParser` — accepts optional `GAME_ID`.
+- Handler: `PlayerFoldHandler` — validates the session, resolves the lobby by id when provided or by session otherwise and forwards to `GameController`.
+
+### Success Response
+
+No additional response fields. Server replies with `+OK` on success.
+
+### Error Response
+
+| Code | Description |
+| :--- | :---------- |
+| `NOT_YOUR_TURN` | The player attempted to fold when not their turn |
+| `GAME_NOT_STARTED` | No game is running in the lobby |
+| `NOT_IN_LOBBY` | Requesting user is not a member of the lobby |
+| `LOBBY_NOT_FOUND` | The specified `GAME_ID` does not exist |
+
+### Example Request
+
+```
+FOLD GAME_ID=1
+```
+
+### Example Response (success)
+
+```
++OK
+END
+```
+
+### Example Response (error)
+
+```
+-ERR
+  CODE=NOT_YOUR_TURN
+  MSG=It is not your turn
+END
+```
+
+## FOLD command
+
+The `FOLD` command lets the currently logged-in player leave the current hand (fold) in the ongoing game for their lobby.
+
+### Required pre-execution checks
+
+- [`UserLoggedInCheck`](#userloggedincheck)
+
+### Request Parameters
+
+| Parameter Name | Type | Optional | Description |
+| :------------- | :--- | :------: | :---------- |
+| `GAME_ID` | `int` | yes | Numeric id of the lobby/game to target. If omitted the server resolves the lobby by the requesting session's user. |
+
+### Implementation notes
+
+- Parser: `PlayerFoldParser` — accepts optional `GAME_ID`.
+- Handler: `PlayerFoldHandler` — validates the session, resolves the lobby by id when provided or by session otherwise and forwards to `GameController`.
+
+### Success Response
+
+No additional response fields. Server replies with `+OK` on success.
+
+### Error Response
+
+| Code | Description |
+| :--- | :---------- |
+| `NOT_YOUR_TURN` | The player attempted to fold when not their turn |
+| `GAME_NOT_STARTED` | No game is running in the lobby |
+| `NOT_IN_LOBBY` | Requesting user is not a member of the lobby |
+| `LOBBY_NOT_FOUND` | The specified `GAME_ID` does not exist |
+
+### Example Request
+
+```
+FOLD GAME_ID=1
+```
+
+### Example Response (success)
+
+```
++OK
+END
+```
+
+### Example Response (error)
+
+```
+-ERR
+  CODE=NOT_YOUR_TURN
+  MSG=It is not your turn
+END
+```
+
+## FOLD command
+
+The `FOLD` command lets the currently logged-in player leave the current hand (fold) in the ongoing game for their lobby.
+
+### Required pre-execution checks
+
+- [`UserLoggedInCheck`](#userloggedincheck)
+
+### Request Parameters
+
+| Parameter Name | Type | Optional | Description |
+| :------------- | :--- | :------: | :---------- |
+| `GAME_ID` | `int` | yes | Numeric id of the lobby/game to target. If omitted the server resolves the lobby by the requesting session's user. |
+
+### Implementation notes
+
+- Parser: `PlayerFoldParser` — accepts optional `GAME_ID`.
+- Handler: `PlayerFoldHandler` — validates the session, resolves the lobby by id when provided or by session otherwise and forwards to `GameController`.
+
+### Success Response
+
+No additional response fields. Server replies with `+OK` on success.
+
+### Error Response
+
+| Code | Description |
+| :--- | :---------- |
+| `NOT_YOUR_TURN` | The player attempted to fold when not their turn |
+| `GAME_NOT_STARTED` | No game is running in the lobby |
+| `NOT_IN_LOBBY` | Requesting user is not a member of the lobby |
+| `LOBBY_NOT_FOUND` | The specified `GAME_ID` does not exist |
+
+### Example Request
+
+```
+FOLD GAME_ID=1
+```
+
+### Example Response (success)
+
+```
++OK
+END
+```
+
+### Example Response (error)
+
+```
+-ERR
+  CODE=NOT_YOUR_TURN
+  MSG=It is not your turn
+END
+```
+
+## FOLD command
+
+The `FOLD` command lets the currently logged-in player leave the current hand (fold) in the ongoing game for their lobby.
+
+### Required pre-execution checks
+
+- [`UserLoggedInCheck`](#userloggedincheck)
+
+### Request Parameters
+
+| Parameter Name | Type | Optional | Description |
+| :------------- | :--- | :------: | :---------- |
+| `GAME_ID` | `int` | yes | Numeric id of the lobby/game to target. If omitted the server resolves the lobby by the requesting session's user. |
+
+### Implementation notes
+
+- Parser: `PlayerFoldParser` — accepts optional `GAME_ID`.
+- Handler: `PlayerFoldHandler` — validates the session, resolves the lobby by id when provided or by session otherwise and forwards to `GameController`.
+
+### Success Response
+
+No additional response fields. Server replies with `+OK` on success.
+
+### Error Response
+
+| Code | Description |
+| :--- | :---------- |
+| `NOT_YOUR_TURN` | The player attempted to fold when not their turn |
+| `GAME_NOT_STARTED` | No game is running in the lobby |
+| `NOT_IN_LOBBY` | Requesting user is not a member of the lobby |
+| `LOBBY_NOT_FOUND` | The specified `GAME_ID` does not exist |
+
+### Example Request
+
+```
+FOLD GAME_ID=1
+```
+
+### Example Response (success)
+
+```
++OK
+END
+```
+
+### Example Response (error)
+
+```
+-ERR
+  CODE=NOT_YOUR_TURN
+  MSG=It is not your turn
+END
+```
+
 ## GET_LOBBY_STATUS command
 
 The `GET_LOBBY_STATUS` command requests the server to return the current state of a lobby, including the list of players and their ready state.