fix(api_server): report hermes version on /health and /health/detailed (#40620)

Salvaged from #40479; re-verified on main, tightened, tested.

Co-authored-by: tfournet <tfournet@users.noreply.github.com>

gateway/platforms/api_server.py

@@ -61,6 +61,29 @@ from gateway.platforms.base import (
 
 logger = logging.getLogger(__name__)
 
+
+def _hermes_version() -> str:
+    """Return the hermes-agent version string, or "dev" if it can't be resolved.
+
+    Tries the installed package metadata first (authoritative for a pip/uv
+    install), then the in-tree ``hermes_cli.__version__`` (covers editable /
+    source checkouts where metadata may be stale or absent). Never raises —
+    a version probe must not be able to break the health endpoint.
+    """
+    try:
+        from importlib.metadata import version
+
+        return version("hermes-agent")
+    except Exception:
+        pass
+    try:
+        from hermes_cli import __version__
+
+        return __version__
+    except Exception:
+        return "dev"
+
+
 # Default settings
 DEFAULT_HOST = "127.0.0.1"
 DEFAULT_PORT = 8642
@@ -1047,7 +1070,9 @@ class APIServerAdapter(BasePlatformAdapter):
 
     async def _handle_health(self, request: "web.Request") -> "web.Response":
         """GET /health — simple health check."""
-        return web.json_response({"status": "ok", "platform": "hermes-agent"})
+        return web.json_response(
+            {"status": "ok", "platform": "hermes-agent", "version": _hermes_version()}
+        )
 
     async def _handle_health_detailed(self, request: "web.Request") -> "web.Response":
         """GET /health/detailed — rich status for cross-container dashboard probing.
@@ -1062,6 +1087,7 @@ class APIServerAdapter(BasePlatformAdapter):
         return web.json_response({
             "status": "ok",
             "platform": "hermes-agent",
+            "version": _hermes_version(),
             "gateway_state": runtime.get("gateway_state"),
             "platforms": runtime.get("platforms", {}),
             "active_agents": runtime.get("active_agents", 0),