feat(gemini): improve request context for support and compatibility

Include the Hermes client name and version with Gemini inference, model and tier checks, and TTS requests. Add focused coverage for the request headers and keep the Gemini-specific context scoped to Google Gemini endpoints.

agent/gemini_native_adapter.py

@@ -32,6 +32,13 @@ from agent.gemini_schema import sanitize_gemini_tool_parameters
 
 logger = logging.getLogger(__name__)
 
+try:
+    import hermes_cli as _hermes_cli
+
+    _HERMES_VERSION = str(_hermes_cli.__version__)
+except Exception:
+    _HERMES_VERSION = "0.0.0"
+
 DEFAULT_GEMINI_BASE_URL = "https://generativelanguage.googleapis.com/v1beta"
 
 # Published max output-token ceiling shared by every current Gemini text model
@@ -99,7 +106,10 @@ def probe_gemini_tier(
                 url,
                 params={"key": key},
                 json=payload,
-                headers={"Content-Type": "application/json"},
+                headers={
+                    "Content-Type": "application/json",
+                    "X-Goog-Api-Client": f"hermes-agent/{_HERMES_VERSION}",
+                },
             )
     except Exception as exc:
         logger.debug("probe_gemini_tier: network error: %s", exc)
@@ -901,7 +911,11 @@ class GeminiNativeClient:
             "Content-Type": "application/json",
             "Accept": "application/json",
             "x-goog-api-key": self.api_key,
-            "User-Agent": "hermes-agent (gemini-native)",
+            # Include Hermes client context following Gemini's partner
+            # integration guidance.
+            # See https://ai.google.dev/gemini-api/docs/partner-integration
+            "User-Agent": f"hermes-agent/{_HERMES_VERSION} (gemini-native)",
+            "X-Goog-Api-Client": f"hermes-agent/{_HERMES_VERSION}",
         }
         headers.update(self._default_headers)
         return headers