feat: add vision support validation for image processing

- Introduced a new method in ProviderFactory to check if a model supports vision/image input.
- Updated AgentService and AutoModeService to validate vision support before processing images, throwing an error if the model does not support it.
- Enhanced error messages to guide users on switching models or removing images if necessary.

These changes improve the robustness of image processing by ensuring compatibility with the selected models.

apps/server/src/providers/provider-factory.ts

@@ -156,6 +156,32 @@ export class ProviderFactory {
   static getRegisteredProviderNames(): string[] {
     return Array.from(providerRegistry.keys());
   }
+
+  /**
+   * Check if a specific model supports vision/image input
+   *
+   * @param modelId Model identifier
+   * @returns Whether the model supports vision (defaults to true if model not found)
+   */
+  static modelSupportsVision(modelId: string): boolean {
+    const provider = this.getProviderForModel(modelId);
+    const models = provider.getAvailableModels();
+
+    // Find the model in the available models list
+    for (const model of models) {
+      if (
+        model.id === modelId ||
+        model.modelString === modelId ||
+        model.id.endsWith(`-${modelId}`) ||
+        model.modelString === modelId.replace(/^(claude|cursor|codex)-/, '')
+      ) {
+        return model.supportsVision ?? true;
+      }
+    }
+
+    // Default to true (Claude SDK supports vision by default)
+    return true;
+  }
 }
 
 // =============================================================================

apps/server/src/services/agent-service.ts

@@ -174,6 +174,18 @@ export class AgentService {
       session.thinkingLevel = thinkingLevel;
     }
 
+    // Validate vision support before processing images
+    const effectiveModel = model || session.model;
+    if (imagePaths && imagePaths.length > 0 && effectiveModel) {
+      const supportsVision = ProviderFactory.modelSupportsVision(effectiveModel);
+      if (!supportsVision) {
+        throw new Error(
+          `This model (${effectiveModel}) does not support image input. ` +
+            `Please switch to a model that supports vision, or remove the images and try again.`
+        );
+      }
+    }
+
     // Read images and convert to base64
     const images: Message['images'] = [];
     if (imagePaths && imagePaths.length > 0) {

apps/server/src/services/auto-mode-service.ts

@@ -1989,6 +1989,18 @@ This helps parse your summary correctly in the output logs.`;
     const planningMode = options?.planningMode || 'skip';
     const previousContent = options?.previousContent;
 
+    // Validate vision support before processing images
+    const effectiveModel = model || 'claude-sonnet-4-20250514';
+    if (imagePaths && imagePaths.length > 0) {
+      const supportsVision = ProviderFactory.modelSupportsVision(effectiveModel);
+      if (!supportsVision) {
+        throw new Error(
+          `This model (${effectiveModel}) does not support image input. ` +
+            `Please switch to a model that supports vision (like Claude models), or remove the images and try again.`
+        );
+      }
+    }
+
     // Check if this planning mode can generate a spec/plan that needs approval
     // - spec and full always generate specs
     // - lite only generates approval-ready content when requirePlanApproval is true