diff --git a/hermes_cli/models.py b/hermes_cli/models.py
index 5556da9fdbc..3a8107ed1b4 100644
--- a/hermes_cli/models.py
+++ b/hermes_cli/models.py
@@ -575,6 +575,19 @@ _PROVIDER_MODELS: dict[str, list[str]] = {
         "deepseek/deepseek-r1-0528",
         "qwen/qwen3-235b-a22b-fp8",
     ],
+    # Google Vertex AI — OpenAI-compatible endpoint
+    # (aiplatform.googleapis.com/v1beta1/projects/<proj>/locations/global/endpoints/openapi)
+    # IDs must use the "google/" prefix exactly as returned by the API.
+    # All entries below have been validated live against the antse-tooling GCP
+    # project (global region) and returned HTTP 200 as of 2026-07-21.
+    "vertex": [
+        "google/gemini-3.5-flash",           # frontier Flash; strong agentic + coding
+        "google/gemini-3.6-flash",           # incremental over 3.5-flash (newer)
+        "google/gemini-3.5-flash-lite",      # lighter/cheaper 3.5 Flash variant
+        "google/gemini-3.1-pro-preview",     # 3.1 Pro preview
+        "google/gemini-3-flash-preview",     # 3.0 Flash preview
+        "google/gemini-3.1-flash-lite",      # most cost-efficient Gemini 3.x
+    ],
 }
 
 # ---------------------------------------------------------------------------