fix(amazon-bedrock): preserve empty text blocks when reasoning content is present

.changeset/friendly-schools-drum.md

@@ -0,0 +1,5 @@
+---
+"@ai-sdk/amazon-bedrock": patch
+---
+
+fix(amazon-bedrock): preserve empty text blocks when reasoning content is present

packages/amazon-bedrock/src/bedrock-chat-language-model.test.ts

@@ -4628,6 +4628,76 @@ describe('doGenerate', () => {
     `);
   });
 
+  it('should preserve empty text blocks between reasoning blocks', async () => {
+    server.urls[generateUrl].response = {
+      type: 'json-value',
+      body: {
+        output: {
+          message: {
+            role: 'assistant',
+            content: [
+              {
+                reasoningContent: {
+                  reasoningText: {
+                    text: 'thinking...',
+                    signature: 'sig-1',
+                  },
+                },
+              },
+              { text: '' },
+              {
+                reasoningContent: {
+                  reasoningText: {
+                    text: 'more thinking...',
+                    signature: 'sig-2',
+                  },
+                },
+              },
+              { text: 'The answer is 42.' },
+            ],
+          },
+        },
+        usage: { inputTokens: 4, outputTokens: 34, totalTokens: 38 },
+        stopReason: 'stop_sequence',
+      },
+    };
+
+    const result = await model.doGenerate({
+      prompt: TEST_PROMPT,
+    });
+
+    expect(result.content).toMatchInlineSnapshot(`
+      [
+        {
+          "providerMetadata": {
+            "bedrock": {
+              "signature": "sig-1",
+            },
+          },
+          "text": "thinking...",
+          "type": "reasoning",
+        },
+        {
+          "text": "",
+          "type": "text",
+        },
+        {
+          "providerMetadata": {
+            "bedrock": {
+              "signature": "sig-2",
+            },
+          },
+          "text": "more thinking...",
+          "type": "reasoning",
+        },
+        {
+          "text": "The answer is 42.",
+          "type": "text",
+        },
+      ]
+    `);
+  });
+
   it('should extract reasoning text without signature', async () => {
     server.urls[generateUrl].response = {
       type: 'json-value',

packages/amazon-bedrock/src/bedrock-chat-language-model.ts

@@ -462,7 +462,7 @@ export class BedrockChatLanguageModel implements LanguageModelV4 {
     // map response content to content array
     for (const part of response.output.message.content) {
       // text
-      if (part.text) {
+      if (part.text != null) {
         content.push({ type: 'text', text: part.text });
       }
 

packages/amazon-bedrock/src/convert-to-bedrock-chat-messages.test.ts

@@ -1037,6 +1037,70 @@ describe('assistant messages', () => {
       system: [],
     });
   });
+
+  it('should preserve empty text blocks when reasoning blocks are present', async () => {
+    const result = await convertToBedrockChatMessages([
+      {
+        role: 'user',
+        content: [{ type: 'text', text: 'Hello' }],
+      },
+      {
+        role: 'assistant',
+        content: [
+          {
+            type: 'reasoning',
+            text: 'thinking...',
+            providerOptions: {
+              bedrock: { signature: 'sig-1' },
+            },
+          },
+          { type: 'text', text: '' },
+          {
+            type: 'reasoning',
+            text: 'more thinking...',
+            providerOptions: {
+              bedrock: { signature: 'sig-2' },
+            },
+          },
+          { type: 'text', text: 'response text' },
+          {
+            type: 'tool-call',
+            toolCallId: 'call-123',
+            toolName: 'test',
+            input: {},
+          },
+        ],
+      },
+    ]);
+
+    expect(result).toEqual({
+      messages: [
+        {
+          role: 'user',
+          content: [{ text: 'Hello' }],
+        },
+        {
+          role: 'assistant',
+          content: [
+            {
+              reasoningContent: {
+                reasoningText: { text: 'thinking...', signature: 'sig-1' },
+              },
+            },
+            { text: '' },
+            {
+              reasoningContent: {
+                reasoningText: { text: 'more thinking...', signature: 'sig-2' },
+              },
+            },
+            { text: 'response text' },
+            { toolUse: { toolUseId: 'call-123', name: 'test', input: {} } },
+          ],
+        },
+      ],
+      system: [],
+    });
+  });
 });
 
 describe('tool messages', () => {

packages/amazon-bedrock/src/convert-to-bedrock-chat-messages.ts

@@ -260,15 +260,18 @@ export async function convertToBedrockChatMessages(
           const message = block.messages[j];
           const isLastMessage = j === block.messages.length - 1;
           const { content } = message;
+          const hasReasoningBlocks = content.some(
+            part => part.type === 'reasoning',
+          );
 
           for (let k = 0; k < content.length; k++) {
             const part = content[k];
             const isLastContentPart = k === content.length - 1;
 
             switch (part.type) {
               case 'text': {
-                // Skip empty text blocks
-                if (!part.text.trim()) {
+                // Skip empty text blocks unless reasoning blocks are present
+                if (!part.text.trim() && !hasReasoningBlocks) {
                   break;
                 }