fix(core): pass config to supportsModernFeatures to respect model definition flags

packages/core/src/agents/codebase-investigator.ts

@@ -53,7 +53,7 @@ export const CodebaseInvestigatorAgent = (
 ): LocalAgentDefinition<typeof CodebaseInvestigationReportSchema> => {
   // Use Preview Flash model if the main model supports modern features.
   // If the main model is not a modern model, use the default pro model.
-  const model = supportsModernFeatures(config.getModel())
+  const model = supportsModernFeatures(config.getModel(), config)
     ? PREVIEW_GEMINI_FLASH_MODEL
     : DEFAULT_GEMINI_MODEL;
 
@@ -97,7 +97,7 @@ export const CodebaseInvestigatorAgent = (
       generateContentConfig: {
         temperature: 0.1,
         topP: 0.95,
-        thinkingConfig: supportsModernFeatures(model)
+        thinkingConfig: supportsModernFeatures(model, config)
           ? {
               includeThoughts: true,
               thinkingLevel: ThinkingLevel.HIGH,

packages/core/src/config/models.ts

@@ -397,11 +397,21 @@ export function isCustomModel(
  * This includes Gemini 3 models and any custom models.
  *
  * @param model The model name to check.
+ * @param config Optional config object for dynamic model configuration.
  * @returns True if the model supports modern features like thoughts.
  */
-export function supportsModernFeatures(model: string): boolean {
+export function supportsModernFeatures(
+  model: string,
+  config?: ModelCapabilityContext,
+): boolean {
+  if (config?.getExperimentalDynamicModelConfiguration?.() === true) {
+    const definition = config.modelConfigService.getModelDefinition(model);
+    if (definition?.features?.thinking !== undefined) {
+      return definition.features.thinking;
+    }
+  }
   if (isGemini3Model(model)) return true;
-  return isCustomModel(model);
+  return isCustomModel(model, config);
 }
 
 /**

packages/core/src/core/geminiChat.ts

@@ -569,7 +569,10 @@ export class GeminiChat {
         abortSignal,
       };
 
-      let contentsToUse: Content[] = supportsModernFeatures(modelToUse)
+      let contentsToUse: Content[] = supportsModernFeatures(
+        modelToUse,
+        this.context.config,
+      )
         ? [...contentsForPreviewModel]
         : [...requestContents];
 
@@ -613,7 +616,10 @@ export class GeminiChat {
           );
           lastModelToUse = modelToUse;
           // Re-evaluate contentsToUse based on the new model's feature support
-          contentsToUse = supportsModernFeatures(modelToUse)
+          contentsToUse = supportsModernFeatures(
+            modelToUse,
+            this.context.config,
+          )
             ? [...contentsForPreviewModel]
             : [...requestContents];
         }

packages/core/src/prompts/promptProvider.ts

@@ -69,7 +69,7 @@ export class PromptProvider {
       context.config.getHasAccessToPreviewModel?.() ?? true,
       context.config,
     );
-    const isModernModel = supportsModernFeatures(desiredModel);
+    const isModernModel = supportsModernFeatures(desiredModel, context.config);
     const activeSnippets = isModernModel ? snippets : legacySnippets;
     const contextFilenames = getAllGeminiMdFilenames();
 
@@ -280,7 +280,7 @@ export class PromptProvider {
       context.config.getHasAccessToPreviewModel?.() ?? true,
       context.config,
     );
-    const isModernModel = supportsModernFeatures(desiredModel);
+    const isModernModel = supportsModernFeatures(desiredModel, context.config);
     const activeSnippets = isModernModel ? snippets : legacySnippets;
     return activeSnippets.getCompressionPrompt(
       context.config.getApprovedPlanPath(),