Agent update

docs/architecture/API_REFERENCE.md

@@ -42,6 +42,7 @@ Panel module
 | `remote_server_status` / `server_status` | Structured server status | `gamemanager` | The preferred source for online/start/stop state. |
 | `remote_restart_server` / `restart_server` | Restart a server | `gamemanager` | Intended to be stop, wait, start. |
 | `remote_query` | Query game metadata | `gamemanager` | Optional metadata only. |
+| `exec` | Execute a constrained agent-side command | `gamemanager` fallback status checks, admin tooling | The Game Monitor currently uses this only as a fallback to test whether the configured game port is listening with `ss`/`netstat`. Customer input must not be passed through this path. |
 | `steam_cmd` / `steam` / `automatic_steam_update` | SteamCMD-based update flows | Update actions, Workshop/install tools | Used by Steam-based server maintenance. |
 | `start_file_download` | Download external content | Update/content tools | Returns a PID or progress handle. |
 | `uncompress_file` | Extract archives | Content installers | Used for zip/tar package installs. |
@@ -76,6 +77,25 @@ Return values differ by method, but common patterns are:
 - `UNRESPONSIVE`
 - `UNKNOWN`
 
+The Panel Game Monitor has a defensive fallback path while the structured status system is still being hardened:
+
+```text
+remote_server_status if available
+  -> is_screen_running fallback
+  -> agent-side port listening check through exec
+  -> LGSL/GameQ only for optional player/map/query metadata
+```
+
+A confirmed managed screen/session, process flag, or listening game port is enough for the Panel to display `ONLINE`. Query failure alone must not produce `OFFLINE` or `UNKNOWN`.
+
+Current compatibility behavior:
+
+- New agents should expose `server_status` / `remote_server_status`.
+- Older agents may only expose `is_screen_running` and generic `exec`.
+- The Panel therefore falls back to `is_screen_running` and an agent-side port check.
+- Agents report `ONLINE` when the configured game port is listening even if the managed screen/session cannot be found, with `last_error` carrying the warning.
+- LGSL/GameQ/Steam query data is optional metadata only.
+
 ## Sequence Diagrams
 
 ### Start
@@ -117,7 +137,7 @@ Panel log page
 Agent
   -> read screen log or console log
 Panel
-  -> refresh textarea via AJAX
+  -> refresh dedicated preformatted log panel via AJAX
 ```
 
 ## Error Handling Notes
@@ -126,4 +146,3 @@ Panel
 - Do not treat marker-file presence as the source of truth.
 - Do not expose raw shell execution to customers through generic RPC routes.
 - When a method returns a payload, record the error text in the Panel UI if the operation fails.
-