diff --git a/core/agent-runtime/src/MessageConverter.ts b/core/agent-runtime/src/MessageConverter.ts
index 2bfc768d..80cbb3fe 100644
--- a/core/agent-runtime/src/MessageConverter.ts
+++ b/core/agent-runtime/src/MessageConverter.ts
@@ -23,6 +23,15 @@ export function isToolResultBlock(block: MessageContentBlock): block is ToolResu
   return block.type === ContentBlockType.ToolResult;
 }
 
+interface ThinkingBlock {
+  type: 'thinking';
+  thinking: string;
+}
+
+export function isThinkingBlock(block: MessageContentBlock): block is ThinkingBlock & MessageContentBlock {
+  return block.type === 'thinking';
+}
+
 import { nowUnix, newMsgId } from './AgentStoreUtils';
 import type { RunUsage } from './RunBuilder';
 
@@ -118,49 +127,71 @@ export class MessageConverter {
     return { output, usage };
   }
 
+  /** Content block types allowed in the final assembled message. */
+  private static readonly ALLOWED_BLOCK_TYPES = new Set([
+    ContentBlockType.Text,
+    ContentBlockType.ToolUse,
+    ContentBlockType.ToolResult,
+    'thinking',
+  ]);
+
   /**
    * Normalize raw SDK streaming event blocks (e.g. Anthropic content_block_start/delta/stop)
    * into standard content blocks that mergeContentBlocks can process.
-   * This allows upstream code to transparently pass through SDK events without format conversion.
+   *
+   * Two-phase approach:
+   * 1. Unwrap streaming protocol events to extract actual content
+   * 2. Whitelist filter — only keep known content block types
    */
   static normalizeContentBlocks(blocks: MessageContentBlock[]): MessageContentBlock[] {
-    const result: MessageContentBlock[] = [];
+    const unwrapped: MessageContentBlock[] = [];
     for (const block of blocks) {
       const b = block as Record<string, any>;
-      // content_block_start[tool_use] → ToolUseContentBlock
-      if (b.type === 'content_block_start' && b.content_block?.type === ContentBlockType.ToolUse) {
-        const cb = b.content_block;
-        result.push({ type: ContentBlockType.ToolUse, id: cb.id, name: cb.name, input: cb.input ?? {} } as ToolUseContentBlock);
-        continue;
-      }
-      // content_block_delta[input_json_delta] → TextContentBlock (merged into tool_use.input later)
-      if (b.type === 'content_block_delta' && b.delta?.type === 'input_json_delta') {
-        const partial: string = b.delta.partial_json || '';
-        if (partial) {
-          result.push({ type: ContentBlockType.Text, text: { value: partial, annotations: [] } } as TextContentBlock);
+
+      // --- Phase 1: Unwrap streaming protocol events ---
+
+      // content_block_start → extract tool_use; discard others (text/thinking start are just markers)
+      if (b.type === 'content_block_start') {
+        if (b.content_block?.type === ContentBlockType.ToolUse) {
+          const cb = b.content_block;
+          unwrapped.push({ type: ContentBlockType.ToolUse, id: cb.id, name: cb.name, input: cb.input ?? {} } as ToolUseContentBlock);
         }
         continue;
       }
-      // content_block_delta[text_delta] → TextContentBlock
-      if (b.type === 'content_block_delta' && b.delta?.type === 'text_delta') {
-        const text: string = b.delta.text || '';
-        if (text) {
-          result.push({ type: ContentBlockType.Text, text: { value: text, annotations: [] } } as TextContentBlock);
+
+      // content_block_delta → extract content from known delta subtypes
+      if (b.type === 'content_block_delta') {
+        if (b.delta?.type === 'text_delta') {
+          const text: string = b.delta.text || '';
+          if (text) {
+            unwrapped.push({ type: ContentBlockType.Text, text: { value: text, annotations: [] } } as TextContentBlock);
+          }
+        } else if (b.delta?.type === 'input_json_delta') {
+          const partial: string = b.delta.partial_json || '';
+          if (partial) {
+            unwrapped.push({ type: ContentBlockType.Text, text: { value: partial, annotations: [] } } as TextContentBlock);
+          }
+        } else if (b.delta?.type === 'thinking_delta') {
+          const thinking: string = b.delta.thinking || '';
+          if (thinking) {
+            unwrapped.push({ type: 'thinking', thinking } as unknown as MessageContentBlock);
+          }
         }
+        // Other deltas (signature_delta, etc.) → discard
         continue;
       }
-      // thinking_delta → discard (not part of final message)
-      if (b.type === 'content_block_delta' && b.delta?.type === 'thinking_delta') {
-        continue;
-      }
-      // content_block_stop / message_stop / message_delta → discard
+
+      // Streaming control signals → discard
       if (b.type === 'content_block_stop' || b.type === 'message_stop' || b.type === 'message_delta') {
         continue;
       }
-      // Standard blocks (text, tool_use, tool_result) and other generic blocks → keep as-is
-      result.push(block);
+
+      // Non-streaming blocks (already standard or generic) → pass to phase 2
+      unwrapped.push(block);
     }
-    return result;
+
+    // --- Phase 2: Whitelist filter ---
+    return unwrapped.filter(b => MessageConverter.ALLOWED_BLOCK_TYPES.has(b.type));
   }
 
   /**
@@ -213,6 +244,16 @@ export class MessageConverter {
           type: ContentBlockType.Text,
           text: { value: parts.join(''), annotations: [] },
         });
+      } else if (isThinkingBlock(block)) {
+        // Merge consecutive thinking blocks
+        const parts: string[] = [ (block as unknown as ThinkingBlock).thinking ];
+        let next = blocks[i + 1];
+        while (next && isThinkingBlock(next)) {
+          i++;
+          parts.push((next as unknown as ThinkingBlock).thinking);
+          next = blocks[i + 1];
+        }
+        merged.push({ type: 'thinking', thinking: parts.join('') } as unknown as MessageContentBlock);
       } else {
         merged.push(block);
       }
diff --git a/core/agent-runtime/test/MessageConverter.test.ts b/core/agent-runtime/test/MessageConverter.test.ts
index 3b466608..8283fcca 100644
--- a/core/agent-runtime/test/MessageConverter.test.ts
+++ b/core/agent-runtime/test/MessageConverter.test.ts
@@ -13,7 +13,7 @@ import {
   ContentBlockType,
 } from '@eggjs/tegg-types/agent-runtime';
 
-import { MessageConverter, isTextBlock, isToolUseBlock, isToolResultBlock } from '../src/MessageConverter';
+import { MessageConverter, isTextBlock, isToolUseBlock, isToolResultBlock, isThinkingBlock } from '../src/MessageConverter';
 
 describe('test/MessageConverter.test.ts', () => {
   describe('toContentBlocks', () => {
@@ -381,11 +381,40 @@ describe('test/MessageConverter.test.ts', () => {
       assert.equal(result[0].text.value, 'Hello');
     });
 
-    it('should discard thinking_delta blocks', () => {
+    it('should discard content_block_start for non-tool_use types (thinking, text)', () => {
+      const blocks = [
+        { type: 'content_block_start', index: 0, content_block: { type: 'thinking', thinking: '' } },
+        { type: 'content_block_start', index: 1, content_block: { type: 'text', text: '' } },
+      ] as any;
+      const result = MessageConverter.normalizeContentBlocks(blocks);
+      assert.equal(result.length, 0);
+    });
+
+    it('should extract thinking_delta as thinking block', () => {
       const blocks = [
         { type: 'content_block_delta', delta: { type: 'thinking_delta', thinking: 'let me think...' } },
       ] as any;
       const result = MessageConverter.normalizeContentBlocks(blocks);
+      assert.equal(result.length, 1);
+      assert.equal(result[0].type, 'thinking');
+      assert.equal((result[0] as any).thinking, 'let me think...');
+    });
+
+    it('should discard signature_delta and other unknown delta subtypes', () => {
+      const blocks = [
+        { type: 'content_block_delta', delta: { type: 'signature_delta', signature: 'sig-theta' } },
+        { type: 'content_block_delta', delta: { type: 'some_future_delta', data: 'xxx' } },
+      ] as any;
+      const result = MessageConverter.normalizeContentBlocks(blocks);
+      assert.equal(result.length, 0);
+    });
+
+    it('should discard unknown block types via whitelist', () => {
+      const blocks = [
+        { type: 'ping' },
+        { type: 'some_unknown_event', data: 'xxx' },
+      ] as any;
+      const result = MessageConverter.normalizeContentBlocks(blocks);
       assert.equal(result.length, 0);
     });
 
@@ -531,9 +560,11 @@ describe('test/MessageConverter.test.ts', () => {
       assert.equal(result[3].text.value, 'Here are the results.');
     });
 
-    it('should pass through generic blocks unchanged', () => {
+    it('should merge consecutive thinking blocks into one', () => {
       const blocks = [
-        { type: 'thinking', thinking: 'let me think...' },
+        { type: 'thinking', thinking: 'let ' },
+        { type: 'thinking', thinking: 'me ' },
+        { type: 'thinking', thinking: 'think...' },
       ] as any;
       const result = MessageConverter.mergeContentBlocks(blocks);
       assert.equal(result.length, 1);
@@ -541,14 +572,32 @@ describe('test/MessageConverter.test.ts', () => {
       assert.equal((result[0] as any).thinking, 'let me think...');
     });
 
+    it('should not merge thinking blocks separated by other blocks', () => {
+      const blocks = [
+        { type: 'thinking', thinking: 'first thought' },
+        { type: ContentBlockType.Text, text: { value: 'hello', annotations: [] } },
+        { type: 'thinking', thinking: 'second thought' },
+      ] as any;
+      const result = MessageConverter.mergeContentBlocks(blocks);
+      assert.equal(result.length, 3);
+      assert.equal(result[0].type, 'thinking');
+      assert.equal((result[0] as any).thinking, 'first thought');
+      assert(isTextBlock(result[1]));
+      assert.equal(result[2].type, 'thinking');
+      assert.equal((result[2] as any).thinking, 'second thought');
+    });
+
     it('should handle raw Anthropic SDK stream events end-to-end', () => {
       const blocks = [
         // text deltas
         { type: 'content_block_delta', delta: { type: 'text_delta', text: 'I will ' } },
         { type: 'content_block_delta', delta: { type: 'text_delta', text: 'help you.' } },
         { type: 'content_block_stop' },
-        // thinking (should be discarded)
-        { type: 'content_block_delta', delta: { type: 'thinking_delta', thinking: 'let me think...' } },
+        // thinking deltas (should be merged into one thinking block)
+        { type: 'content_block_delta', delta: { type: 'thinking_delta', thinking: 'let me ' } },
+        { type: 'content_block_delta', delta: { type: 'thinking_delta', thinking: 'think...' } },
+        // signature (should be discarded)
+        { type: 'content_block_delta', delta: { type: 'signature_delta', signature: 'sig-theta' } },
         // tool_use start + input deltas + stop
         { type: 'content_block_start', content_block: { type: 'tool_use', id: 'fc-1', name: 'Bash', input: {} } },
         { type: 'content_block_delta', delta: { type: 'input_json_delta', partial_json: '{"command":' } },
@@ -563,20 +612,23 @@ describe('test/MessageConverter.test.ts', () => {
         { type: 'message_stop' },
       ] as any;
       const result = MessageConverter.mergeContentBlocks(blocks);
-      assert.equal(result.length, 4);
+      assert.equal(result.length, 5);
       // merged text
       assert(isTextBlock(result[0]));
       assert.equal(result[0].text.value, 'I will help you.');
+      // thinking block
+      assert.equal(result[1].type, 'thinking');
+      assert.equal((result[1] as any).thinking, 'let me think...');
       // tool_use with parsed input
-      assert(isToolUseBlock(result[1]));
-      assert.equal(result[1].name, 'Bash');
-      assert.deepStrictEqual(result[1].input, { command: 'ls -la' });
+      assert(isToolUseBlock(result[2]));
+      assert.equal(result[2].name, 'Bash');
+      assert.deepStrictEqual(result[2].input, { command: 'ls -la' });
       // tool_result
-      assert(isToolResultBlock(result[2]));
-      assert.equal(result[2].tool_use_id, 'fc-1');
+      assert(isToolResultBlock(result[3]));
+      assert.equal(result[3].tool_use_id, 'fc-1');
       // merged trailing text
-      assert(isTextBlock(result[3]));
-      assert.equal(result[3].text.value, 'Here are the results.');
+      assert(isTextBlock(result[4]));
+      assert.equal(result[4].text.value, 'Here are the results.');
     });
   });
 
@@ -599,6 +651,12 @@ describe('test/MessageConverter.test.ts', () => {
       assert.equal(block.tool_use_id, 'toolu_1');
     });
 
+    it('isThinkingBlock should identify thinking blocks', () => {
+      const block = { type: 'thinking', thinking: 'hmm...' };
+      assert(isThinkingBlock(block as any));
+      assert(!isThinkingBlock({ type: ContentBlockType.Text, text: { value: 'hi', annotations: [] } } as any));
+    });
+
     it('type guards should return false for non-matching blocks', () => {
       const textBlock = { type: ContentBlockType.Text, text: { value: 'hi', annotations: [] } };
       const toolUseBlock = { type: ContentBlockType.ToolUse, id: 'id', name: 'n', input: {} };