fix(core): Correct Gemma 4 thought extraction and model features

Fixes an issue where the CLI hangs on 'Thinking...' for models (like Gemma 4) that return thought text in the 'thought' field instead of 'text'. Also updates Gemma 4 model definitions to accurately reflect their 'thinking' capabilities.

packages/core/src/config/defaultModelConfigs.ts

@@ -334,7 +334,7 @@ export const DEFAULT_MODEL_CONFIGS: ModelConfigServiceConfig = {
       family: 'gemma-4',
       isPreview: true,
       isVisible: true,
-      features: { thinking: false, multimodalToolUse: false },
+      features: { thinking: true, multimodalToolUse: false },
     },
     'gemma-4-31b-it': {
       tier: 'pro',

packages/core/src/core/geminiChat.ts

@@ -1072,9 +1072,13 @@ export class GeminiChat {
     }
 
     const thoughtPart = content.parts[0];
-    if (thoughtPart.text) {
+    const rawText =
+      typeof thoughtPart.thought === 'string'
+        ? thoughtPart.thought
+        : (thoughtPart.text ?? '');
+
+    if (rawText) {
       // Extract subject and description using the same logic as turn.ts
-      const rawText = thoughtPart.text;
       const subjectStringMatches = rawText.match(/\*\*(.*?)\*\*/s);
       const subject = subjectStringMatches
         ? subjectStringMatches[1].trim()

packages/core/src/core/turn.test.ts

@@ -733,7 +733,7 @@ describe('Turn', () => {
       },
       {
         description: 'should yield thought events with traceId',
-        part: { text: '[Thought: thinking]', thought: 'thinking' },
+        part: { text: '[Thought: thinking]', thought: true },
         responseId: 'trace-456',
         expectedEvent: {
           type: GeminiEventType.Thought,
@@ -774,7 +774,7 @@ describe('Turn', () => {
               {
                 content: {
                   parts: [
-                    { text: '**Planning** the solution', thought: 'planning' },
+                    { text: '**Planning** the solution', thought: true },
                     { text: 'I will help you with that.' },
                   ],
                 },

packages/core/src/core/turn.ts

@@ -308,7 +308,11 @@ export class Turn {
         const parts = resp.candidates?.[0]?.content?.parts ?? [];
         for (const part of parts) {
           if (part.thought) {
-            const thought = parseThought(part.text ?? '');
+            const rawThought =
+              typeof part.thought === 'string'
+                ? part.thought
+                : (part.text ?? '');
+            const thought = parseThought(rawThought);
             yield {
               type: GeminiEventType.Thought,
               value: thought,