feat: add yolo mode support to auto vision model switch (#652)

* feat: add yolo mode support to auto vision model switch

* feat: add cli args & env variables for switch behavoir

* fix: use dedicated model names and settings

* docs: add vision model instructions

* fix: failed test case

* fix: setModel failure

README.md

@@ -54,6 +54,7 @@ For detailed setup instructions, see [Authorization](#authorization).
 - **Code Understanding & Editing** - Query and edit large codebases beyond traditional context window limits
 - **Workflow Automation** - Automate operational tasks like handling pull requests and complex rebases
 - **Enhanced Parser** - Adapted parser specifically optimized for Qwen-Coder models
+- **Vision Model Support** - Automatically detect images in your input and seamlessly switch to vision-capable models for multimodal analysis
 
 ## Installation
 
@@ -121,6 +122,58 @@ Create or edit `.qwen/settings.json` in your home directory:
 
 > 📝 **Note**: Session token limit applies to a single conversation, not cumulative API calls.
 
+### Vision Model Configuration
+
+Qwen Code includes intelligent vision model auto-switching that detects images in your input and can automatically switch to vision-capable models for multimodal analysis. **This feature is enabled by default** - when you include images in your queries, you'll see a dialog asking how you'd like to handle the vision model switch.
+
+#### Skip the Switch Dialog (Optional)
+
+If you don't want to see the interactive dialog each time, configure the default behavior in your `.qwen/settings.json`:
+
+```json
+{
+  "experimental": {
+    "vlmSwitchMode": "once"
+  }
+}
+```
+
+**Available modes:**
+
+- **`"once"`** - Switch to vision model for this query only, then revert
+- **`"session"`** - Switch to vision model for the entire session
+- **`"persist"`** - Continue with current model (no switching)
+- **Not set** - Show interactive dialog each time (default)
+
+#### Command Line Override
+
+You can also set the behavior via command line:
+
+```bash
+# Switch once per query
+qwen --vlm-switch-mode once
+
+# Switch for entire session
+qwen --vlm-switch-mode session
+
+# Never switch automatically
+qwen --vlm-switch-mode persist
+```
+
+#### Disable Vision Models (Optional)
+
+To completely disable vision model support, add to your `.qwen/settings.json`:
+
+```json
+{
+  "experimental": {
+    "visionModelPreview": false
+  }
+}
+```
+
+> 💡 **Tip**: In YOLO mode (`--yolo`), vision switching happens automatically without prompts when images are detected.
+
 ### Authorization
 
 Choose your preferred authentication method based on your needs: