[Gemma x Gemini CLI] Add an Experimental Gemma Router that uses a LiteRT-LM shim into the Composite Model Classifier Strategy (#17231)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Allen Hutchison <adh@google.com>

docs/cli/settings.md

@@ -140,6 +140,7 @@ they appear in the UI.
 | Plan                       | `experimental.plan`                      | Enable planning features (Plan Mode and tools).                                                                                                           | `false` |
 | Model Steering             | `experimental.modelSteering`             | Enable model steering (user hints) to guide the model during tool execution.                                                                              | `false` |
 | Direct Web Fetch           | `experimental.directWebFetch`            | Enable web fetch behavior that bypasses LLM summarization.                                                                                                | `false` |
+| Enable Gemma Model Router  | `experimental.gemmaModelRouter.enabled`  | Enable the Gemma Model Router. Requires a local endpoint serving Gemma via the Gemini API using LiteRT-LM shim.                                           | `false` |
 
 ### Skills
 

docs/reference/configuration.md

@@ -1014,6 +1014,23 @@ their corresponding top-level category object in your `settings.json` file.
   - **Default:** `false`
   - **Requires restart:** Yes
 
+- **`experimental.gemmaModelRouter.enabled`** (boolean):
+  - **Description:** Enable the Gemma Model Router. Requires a local endpoint
+    serving Gemma via the Gemini API using LiteRT-LM shim.
+  - **Default:** `false`
+  - **Requires restart:** Yes
+
+- **`experimental.gemmaModelRouter.classifier.host`** (string):
+  - **Description:** The host of the classifier.
+  - **Default:** `"http://localhost:9379"`
+  - **Requires restart:** Yes
+
+- **`experimental.gemmaModelRouter.classifier.model`** (string):
+  - **Description:** The model to use for the classifier. Only tested on
+    `gemma3-1b-gpu-custom`.
+  - **Default:** `"gemma3-1b-gpu-custom"`
+  - **Requires restart:** Yes
+
 #### `skills`
 
 - **`skills.enabled`** (boolean):