server content features improved

docs/features/SERVER_CONTENT_APPLICATION_HOOKS.md

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+# Server Content Application Hooks
+
+Server Content Application Hooks let installed server content manage companion
+applications such as BEC, Big Brother Bot, Discord bridges, RCON tools, and log
+watchers as part of the game server lifecycle.
+
+The application files may live wherever the game requires them. GSP lifecycle
+metadata lives under each server home:
+
+```text
+_gsp_content/
+  hooks/
+  generated/
+  runtime/
+```
+
+## Content Type
+
+The Server Content Manager includes the `Server-side Application` content type.
+When this type is installed, the Panel writes a JSON hook manifest to:
+
+```text
+_gsp_content/hooks/<app>.json
+```
+
+The agents read these manifests during server startup.
+
+## Hook Manifest
+
+```json
+{
+  "name": "BEC",
+  "enabled": true,
+  "platform": "windows",
+  "working_dir": "bec",
+  "start_command": "BEC.exe -f Config.cfg",
+  "stop_command": "",
+  "start_timing": "before_server",
+  "stop_with_server": true,
+  "watch": true,
+  "critical": true,
+  "kill_game_if_app_exits": false,
+  "restart_app_if_exits": true,
+  "pid_name": "bec",
+  "app_name": "BEC.exe",
+  "description": "Battleye Extended Controls watchdog for DayZ/Arma servers"
+}
+```
+
+Supported `platform` values are `windows`, `linux`, and `both`.
+Supported `start_timing` values are `before_server` and `after_server`.
+
+## Runtime PID File
+
+Agents write hook runtime PIDs to:
+
+```text
+_gsp_content/runtime/server_content.pids
+```
+
+Format:
+
+```text
+watchdog|BEC|12345
+app|BEC|12346
+```
+
+The main game server watchdog PID is not stored in this file.
+
+## Lifecycle
+
+On server start, the agent:
+
+1. Creates `_gsp_content/hooks`, `_gsp_content/generated`, and `_gsp_content/runtime`.
+2. Reads enabled hook manifests matching the agent platform.
+3. Generates platform-specific hook watchdog scripts.
+4. Starts `before_server` hooks.
+5. Starts the game server.
+6. Starts `after_server` hooks.
+7. Cleans up hook watchdogs and apps when the game server exits.
+
+On Panel Stop or Restart, agents kill hook watchdog PIDs first and hook app PIDs
+second, then continue normal game process and screen/session cleanup.
+
+## Legacy `_alsoRun.bat`
+
+Windows `_alsoRun.bat` support remains for compatibility, but it is deprecated.
+New companion applications should be installed as `Server-side Application`
+content so both Linux and Windows agents can manage them through the same hook
+contract.