feat: enable interleaved thinking for Claude 4 models (#323)

*Issue #, if available:*

closes #322 

*Description of changes:*



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Author: tmokmss

packages/agent-core/src/lib/converse.ts

@@ -144,6 +144,10 @@ const preProcessInput = (
       ...input.inferenceConfig,
       maxTokens: Math.max(adjustedMaxToken, Math.min(budget * 2, modelConfig.maxOutputTokens)),
     };
+
+    if (modelConfig.interleavedThinkingSupport) {
+      input.additionalModelRequestFields.anthropic_beta = ['interleaved-thinking-2025-05-14'];
+    }
   } else {
     // when we disable reasoning, we have to remove
     // reasoningContent blocks from all the previous message contents

packages/agent-core/src/schema/model.ts

@@ -22,6 +22,7 @@ const modelConfigSchema = z.object({
   reasoningSupport: z.boolean(),
   toolChoiceSupport: z.array(z.enum(['any', 'auto', 'tool'])),
   isHidden: z.boolean().optional(),
+  interleavedThinkingSupport: z.boolean().optional(),
   pricing: z.object({
     input: z.number(),
     output: z.number(),
@@ -92,6 +93,7 @@ export const modelConfigs: Record<ModelType, z.infer<typeof modelConfigSchema>>
     reasoningSupport: true,
     toolChoiceSupport: ['any', 'auto', 'tool'],
     isHidden: true,
+    interleavedThinkingSupport: true,
     pricing: { input: 0.015, output: 0.075, cacheRead: 0.0015, cacheWrite: 0.01875 },
   },
   'opus4.1': {
@@ -102,6 +104,7 @@ export const modelConfigs: Record<ModelType, z.infer<typeof modelConfigSchema>>
     cacheSupport: ['system', 'message', 'tool'],
     reasoningSupport: true,
     toolChoiceSupport: ['any', 'auto', 'tool'],
+    interleavedThinkingSupport: true,
     pricing: { input: 0.015, output: 0.075, cacheRead: 0.0015, cacheWrite: 0.01875 },
   },
   sonnet4: {
@@ -112,6 +115,7 @@ export const modelConfigs: Record<ModelType, z.infer<typeof modelConfigSchema>>
     cacheSupport: ['system', 'message', 'tool'],
     reasoningSupport: true,
     toolChoiceSupport: ['any', 'auto', 'tool'],
+    interleavedThinkingSupport: true,
     pricing: { input: 0.003, output: 0.015, cacheRead: 0.0003, cacheWrite: 0.00375 },
   },
 };