diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 86529a56..eb7f95c7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,16 +40,14 @@ jobs:
         with:
           node-version: '22'
 
-      - name: Restore bun + node_modules cache
+      - name: Restore bun package cache
         uses: actions/cache@v4
         with:
           path: |
             ~/.bun/install/cache
-            node_modules
-            ui/node_modules
-          key: ${{ runner.os }}-bun-${{ hashFiles('bun.lock', 'ui/bun.lock') }}
+          key: ${{ runner.os }}-bun-cache-v2-${{ hashFiles('bun.lock', 'ui/bun.lock') }}
           restore-keys: |
-            ${{ runner.os }}-bun-
+            ${{ runner.os }}-bun-cache-v2-
 
       - name: Ensure dependencies
         run: bash scripts/ensure-deps.sh
@@ -74,16 +72,14 @@ jobs:
         with:
           node-version: '22'
 
-      - name: Restore bun + node_modules cache
+      - name: Restore bun package cache
         uses: actions/cache@v4
         with:
           path: |
             ~/.bun/install/cache
-            node_modules
-            ui/node_modules
-          key: ${{ runner.os }}-bun-${{ hashFiles('bun.lock', 'ui/bun.lock') }}
+          key: ${{ runner.os }}-bun-cache-v2-${{ hashFiles('bun.lock', 'ui/bun.lock') }}
           restore-keys: |
-            ${{ runner.os }}-bun-
+            ${{ runner.os }}-bun-cache-v2-
 
       - name: Ensure dependencies
         run: bash scripts/ensure-deps.sh
@@ -117,16 +113,14 @@ jobs:
         with:
           node-version: '22'
 
-      - name: Restore bun + node_modules cache
+      - name: Restore bun package cache
         uses: actions/cache@v4
         with:
           path: |
             ~/.bun/install/cache
-            node_modules
-            ui/node_modules
-          key: ${{ runner.os }}-bun-${{ hashFiles('bun.lock', 'ui/bun.lock') }}
+          key: ${{ runner.os }}-bun-cache-v2-${{ hashFiles('bun.lock', 'ui/bun.lock') }}
           restore-keys: |
-            ${{ runner.os }}-bun-
+            ${{ runner.os }}-bun-cache-v2-
 
       - name: Ensure dependencies
         run: bash scripts/ensure-deps.sh
diff --git a/src/glmt/delta-accumulator.ts b/src/glmt/delta-accumulator.ts
index 4988c9e8..7915267c 100644
--- a/src/glmt/delta-accumulator.ts
+++ b/src/glmt/delta-accumulator.ts
@@ -40,6 +40,7 @@ interface ToolCall {
     name: string;
     arguments: string;
   };
+  blockIndex: number;
 }
 
 interface ToolCallDelta {
@@ -240,7 +241,6 @@ export class DeltaAccumulator {
   addToolCallDelta(toolCallDelta: ToolCallDelta): void {
     const index = toolCallDelta.index;
 
-    // Initialize tool call if not exists
     if (!this.toolCallsIndex[index]) {
       const toolCall: ToolCall = {
         index: index,
@@ -250,6 +250,7 @@ export class DeltaAccumulator {
           name: '',
           arguments: '',
         },
+        blockIndex: -1,
       };
       this.toolCalls.push(toolCall);
       this.toolCallsIndex[index] = toolCall;
@@ -257,27 +258,42 @@ export class DeltaAccumulator {
 
     const toolCall = this.toolCallsIndex[index];
 
-    // Update id if present
     if (toolCallDelta.id) {
       toolCall.id = toolCallDelta.id;
     }
 
-    // Update type if present
     if (toolCallDelta.type) {
       toolCall.type = toolCallDelta.type;
     }
 
-    // Update function name if present
     if (toolCallDelta.function?.name) {
       toolCall.function.name += toolCallDelta.function.name;
     }
 
-    // Update function arguments if present
     if (toolCallDelta.function?.arguments) {
       toolCall.function.arguments += toolCallDelta.function.arguments;
     }
   }
 
+  setToolCallBlockIndex(toolCallIndex: number, blockIndex: number): void {
+    const toolCall = this.toolCallsIndex[toolCallIndex];
+    if (toolCall) {
+      toolCall.blockIndex = blockIndex;
+    }
+  }
+
+  getToolCallBlockIndex(toolCallIndex: number): number {
+    const toolCall = this.toolCallsIndex[toolCallIndex];
+    if (!toolCall || toolCall.blockIndex < 0) {
+      throw new Error(`Tool call ${toolCallIndex} does not have an assigned content block`);
+    }
+    return toolCall.blockIndex;
+  }
+
+  getUnstoppedBlocks(): ContentBlock[] {
+    return this.contentBlocks.filter((b) => !b.stopped);
+  }
+
   /**
    * Get all tool calls
    * @returns Tool calls array
diff --git a/src/glmt/pipeline/stream-parser.ts b/src/glmt/pipeline/stream-parser.ts
index c0b6fc71..b72218a2 100644
--- a/src/glmt/pipeline/stream-parser.ts
+++ b/src/glmt/pipeline/stream-parser.ts
@@ -209,9 +209,8 @@ export class StreamParser {
 
     if (!toolCallDeltas) return events;
 
-    // Close current content block ONCE before processing any tool calls
     const currentBlock = accumulator.getCurrentBlock();
-    if (currentBlock && !currentBlock.stopped) {
+    if (currentBlock && !currentBlock.stopped && currentBlock.type !== 'tool_use') {
       if (currentBlock.type === 'thinking') {
         events.push(...this.closeThinkingBlock(currentBlock, accumulator));
       } else {
@@ -220,7 +219,6 @@ export class StreamParser {
       }
     }
 
-    // Process tool call deltas
     events.push(...this.toolCallHandler.processToolCallDeltas(toolCallDeltas, accumulator));
 
     return events;
@@ -251,44 +249,41 @@ export class StreamParser {
   private forceFinalization(accumulator: DeltaAccumulator): AnthropicSSEEvent[] {
     const events: AnthropicSSEEvent[] = [];
 
-    // Close current block if any
-    const currentBlock = accumulator.getCurrentBlock();
-    if (currentBlock && !currentBlock.stopped) {
-      if (currentBlock.type === 'thinking') {
-        events.push(...this.closeThinkingBlock(currentBlock, accumulator));
-      } else {
-        events.push(this.responseBuilder.createContentBlockStopEvent(currentBlock));
-        accumulator.stopCurrentBlock();
+    const unstoppedBlocks = accumulator.getUnstoppedBlocks();
+    for (const block of unstoppedBlocks) {
+      if (block.type === 'thinking') {
+        const signatureEvent = this.responseBuilder.createSignatureDeltaEvent(block);
+        if (signatureEvent) {
+          events.push(signatureEvent);
+        }
       }
+      events.push(this.responseBuilder.createContentBlockStopEvent(block));
+      block.stopped = true;
     }
 
-    // Force finalization
     events.push(...this.finalizeDelta(accumulator));
     return events;
   }
 
-  /**
-   * Finalize streaming and generate closing events
-   */
   finalizeDelta(accumulator: DeltaAccumulator): AnthropicSSEEvent[] {
     if (accumulator.isFinalized()) {
-      return []; // Already finalized
+      return [];
     }
 
     const events: AnthropicSSEEvent[] = [];
 
-    // Close current content block if any
-    const currentBlock = accumulator.getCurrentBlock();
-    if (currentBlock && !currentBlock.stopped) {
-      if (currentBlock.type === 'thinking') {
-        events.push(...this.closeThinkingBlock(currentBlock, accumulator));
-      } else {
-        events.push(this.responseBuilder.createContentBlockStopEvent(currentBlock));
-        accumulator.stopCurrentBlock();
+    const unstoppedBlocks = accumulator.getUnstoppedBlocks();
+    for (const block of unstoppedBlocks) {
+      if (block.type === 'thinking') {
+        const signatureEvent = this.responseBuilder.createSignatureDeltaEvent(block);
+        if (signatureEvent) {
+          events.push(signatureEvent);
+        }
       }
+      events.push(this.responseBuilder.createContentBlockStopEvent(block));
+      block.stopped = true;
     }
 
-    // Message delta (stop reason + usage) and message stop
     const stopReason = this.responseBuilder.mapStopReason(accumulator.getFinishReason() || 'stop');
     events.push(...this.responseBuilder.createFinalizationEvents(accumulator, stopReason));
 
diff --git a/src/glmt/pipeline/tool-call-handler.ts b/src/glmt/pipeline/tool-call-handler.ts
index ffe0d670..251813a4 100644
--- a/src/glmt/pipeline/tool-call-handler.ts
+++ b/src/glmt/pipeline/tool-call-handler.ts
@@ -11,9 +11,6 @@ import type { DeltaAccumulator } from '../delta-accumulator';
 import type { OpenAIToolCallDelta, OpenAIToolCall, ContentBlock, AnthropicSSEEvent } from './types';
 
 export class ToolCallHandler {
-  /**
-   * Process tool calls from non-streaming response
-   */
   processToolCalls(toolCalls: OpenAIToolCall[]): ContentBlock[] {
     const content: ContentBlock[] = [];
 
@@ -38,10 +35,6 @@ export class ToolCallHandler {
     return content;
   }
 
-  /**
-   * Process tool call deltas during streaming
-   * Returns events for tool use blocks and input_json deltas
-   */
   processToolCallDeltas(
     toolCallDeltas: OpenAIToolCallDelta[],
     accumulator: DeltaAccumulator
@@ -49,15 +42,15 @@ export class ToolCallHandler {
     const events: AnthropicSSEEvent[] = [];
 
     for (const toolCallDelta of toolCallDeltas) {
-      // Track tool call state
       const isNewToolCall = !accumulator.hasToolCall(toolCallDelta.index);
       accumulator.addToolCallDelta(toolCallDelta);
 
-      // Emit tool use events (start + input_json deltas)
       if (isNewToolCall) {
-        // Start new tool_use block in accumulator
+        // OpenAI may interleave tool_call fragments across chunks, so blocks must stay open
+        // until the stream finalizes. Closing on a later index truncates earlier tool input.
         const block = accumulator.startBlock('tool_use');
         const toolCall = accumulator.getToolCall(toolCallDelta.index);
+        accumulator.setToolCallBlockIndex(toolCallDelta.index, block.index);
 
         events.push({
           event: 'content_block_start',
@@ -68,27 +61,25 @@ export class ToolCallHandler {
               type: 'tool_use',
               id: toolCall?.id || `tool_${toolCallDelta.index}`,
               name: toolCall?.function?.name || '',
+              input: {},
             },
           },
         });
       }
 
-      // Emit input_json delta if arguments present
       if (toolCallDelta.function?.arguments) {
-        const currentToolBlock = accumulator.getCurrentBlock();
-        if (currentToolBlock && currentToolBlock.type === 'tool_use') {
-          events.push({
-            event: 'content_block_delta',
-            data: {
-              type: 'content_block_delta',
-              index: currentToolBlock.index,
-              delta: {
-                type: 'input_json_delta',
-                partial_json: toolCallDelta.function.arguments,
-              },
+        const toolCallBlockIndex = accumulator.getToolCallBlockIndex(toolCallDelta.index);
+        events.push({
+          event: 'content_block_delta',
+          data: {
+            type: 'content_block_delta',
+            index: toolCallBlockIndex,
+            delta: {
+              type: 'input_json_delta',
+              partial_json: toolCallDelta.function.arguments,
             },
-          });
-        }
+          },
+        });
       }
     }
 
diff --git a/src/proxy/server/messages-route.ts b/src/proxy/server/messages-route.ts
index 95388e00..965e67a3 100644
--- a/src/proxy/server/messages-route.ts
+++ b/src/proxy/server/messages-route.ts
@@ -139,20 +139,13 @@ export function attachDisconnectAbortHandlers(
 
   const cleanupFns = [
     registerOnceListener(req, 'aborted', () => abortOnDisconnect('req.aborted')),
-    registerOnceListener(req, 'close', () => abortOnDisconnect('req.close')),
     registerOnceListener(req.socket, 'close', () => abortOnDisconnect('req.socket.close')),
-    registerOnceListener(res, 'close', () => abortOnDisconnect('res.close')),
     registerOnceListener(res.socket, 'close', () => abortOnDisconnect('res.socket.close')),
   ];
 
   const disconnectPoll = setInterval(() => {
-    if (
-      req.destroyed ||
-      res.destroyed ||
-      req.socket?.destroyed === true ||
-      res.socket?.destroyed === true
-    ) {
-      abortOnDisconnect('poll.destroyed');
+    if (req.socket?.destroyed === true) {
+      abortOnDisconnect('poll.socket.destroyed');
     }
   }, 50);
 
diff --git a/src/proxy/server/proxy-server.ts b/src/proxy/server/proxy-server.ts
index 4b68f2a1..d5e99d11 100644
--- a/src/proxy/server/proxy-server.ts
+++ b/src/proxy/server/proxy-server.ts
@@ -35,32 +35,42 @@ export function startOpenAICompatProxyServer(options: OpenAICompatProxyServerOpt
     const pathname =
       parsedUrl.pathname.length > 1 ? parsedUrl.pathname.replace(/\/+$/, '') : parsedUrl.pathname;
 
-    if (method === 'GET' && pathname === '/health') {
-      writeJson(res, 200, {
-        ok: true,
-        service: OPENAI_COMPAT_PROXY_SERVICE_NAME,
-        host,
-        profile: options.profile.profileName,
-        port: options.port,
-      });
+    if ((method === 'GET' || method === 'HEAD') && pathname === '/health') {
+      if (method === 'HEAD') {
+        res.writeHead(200, { 'Content-Type': 'application/json' });
+        res.end();
+      } else {
+        writeJson(res, 200, {
+          ok: true,
+          service: OPENAI_COMPAT_PROXY_SERVICE_NAME,
+          host,
+          profile: options.profile.profileName,
+          port: options.port,
+        });
+      }
       return;
     }
 
-    if (method === 'GET' && pathname === '/') {
-      writeJson(res, 200, {
-        ok: true,
-        service: OPENAI_COMPAT_PROXY_SERVICE_NAME,
-        bind: {
-          host,
-          port: options.port,
-        },
-        profile: {
-          name: options.profile.profileName,
-          provider: options.profile.provider,
-          model: options.profile.model || null,
-        },
-        endpoints: ['/health', '/v1/messages', '/v1/models'],
-      });
+    if ((method === 'GET' || method === 'HEAD') && pathname === '/') {
+      if (method === 'HEAD') {
+        res.writeHead(200, { 'Content-Type': 'application/json' });
+        res.end();
+      } else {
+        writeJson(res, 200, {
+          ok: true,
+          service: OPENAI_COMPAT_PROXY_SERVICE_NAME,
+          bind: {
+            host,
+            port: options.port,
+          },
+          profile: {
+            name: options.profile.profileName,
+            provider: options.profile.provider,
+            model: options.profile.model || null,
+          },
+          endpoints: ['/health', '/v1/messages', '/v1/models'],
+        });
+      }
       return;
     }
 
diff --git a/src/proxy/transformers/request-transformer.ts b/src/proxy/transformers/request-transformer.ts
index c1ebd5d7..a8ccb98c 100644
--- a/src/proxy/transformers/request-transformer.ts
+++ b/src/proxy/transformers/request-transformer.ts
@@ -458,9 +458,34 @@ function transformMessages(messagesValue: unknown): OpenAIMessage[] {
 
     if (role === 'user') {
       const userParts: OpenAIContentPart[] = [];
-      let sawToolResult = false;
+      const followUpParts: OpenAIContentPart[] = [];
       const resolvedToolUseIds = new Set<string>();
 
+      const handleUserPart = (
+        part: OpenAIContentPart,
+        blockIndex: number,
+        kind: 'text' | 'image'
+      ) => {
+        if (!pendingToolUseIds || pendingToolUseIds.size === 0) {
+          userParts.push(part);
+          return;
+        }
+
+        if (resolvedToolUseIds.size === 0) {
+          throw new Error(
+            `messages[${messageIndex}].content[${blockIndex}] ${kind} is not allowed before tool_result blocks for pending tool_use ids`
+          );
+        }
+
+        if (resolvedToolUseIds.size !== pendingToolUseIds.size) {
+          throw new Error(
+            `messages[${messageIndex}].content[${blockIndex}] ${kind} is not allowed between tool_result blocks for pending tool_use ids`
+          );
+        }
+
+        followUpParts.push(part);
+      };
+
       content.forEach((block, blockIndex) => {
         const parsed = assertObject(
           block,
@@ -472,23 +497,17 @@ function transformMessages(messagesValue: unknown): OpenAIMessage[] {
         }
 
         if (parsed.type === 'text') {
-          if (sawToolResult) {
-            throw new Error(
-              `messages[${messageIndex}].content[${blockIndex}] text is not allowed after tool_result blocks`
-            );
-          }
           const text = typeof parsed.text === 'string' ? parsed.text : '';
-          userParts.push({ type: 'text', text });
+          handleUserPart({ type: 'text', text }, blockIndex, 'text');
           return;
         }
 
         if (isImageBlock(parsed)) {
-          if (sawToolResult) {
-            throw new Error(
-              `messages[${messageIndex}].content[${blockIndex}] image is not allowed after tool_result blocks`
-            );
-          }
-          userParts.push(toImagePart(parsed, `messages[${messageIndex}].content[${blockIndex}]`));
+          handleUserPart(
+            toImagePart(parsed, `messages[${messageIndex}].content[${blockIndex}]`),
+            blockIndex,
+            'image'
+          );
           return;
         }
 
@@ -498,11 +517,6 @@ function transformMessages(messagesValue: unknown): OpenAIMessage[] {
               `messages[${messageIndex}].content[${blockIndex}] tool_result requires a preceding assistant tool_use`
             );
           }
-          if (userParts.length > 0) {
-            throw new Error(
-              `messages[${messageIndex}].content[${blockIndex}] tool_result blocks must come before other user content`
-            );
-          }
           if (typeof parsed.tool_use_id !== 'string' || parsed.tool_use_id.trim().length === 0) {
             throw new Error(
               `messages[${messageIndex}].content[${blockIndex}].tool_use_id must be a non-empty string`
@@ -518,7 +532,6 @@ function transformMessages(messagesValue: unknown): OpenAIMessage[] {
               `messages[${messageIndex}].content[${blockIndex}].tool_use_id "${parsed.tool_use_id}" is duplicated`
             );
           }
-          sawToolResult = true;
           resolvedToolUseIds.add(parsed.tool_use_id);
           translatedMessages.push({
             role: 'tool',
@@ -543,7 +556,7 @@ function transformMessages(messagesValue: unknown): OpenAIMessage[] {
         );
       });
 
-      if (sawToolResult) {
+      if (resolvedToolUseIds.size > 0) {
         if (resolvedToolUseIds.size !== pendingToolUseIds?.size) {
           throw new Error(
             `messages[${messageIndex}].content must provide tool_result blocks for all pending tool_use ids`
@@ -551,18 +564,21 @@ function transformMessages(messagesValue: unknown): OpenAIMessage[] {
         }
         pendingToolUseIds = null;
         hasPendingToolUseIds = false;
-        return;
       }
 
       if (pendingToolUseIds && pendingToolUseIds.size > 0) {
         throw new Error(
-          `messages[${messageIndex}].content must start with tool_result blocks for pending tool_use ids`
+          `messages[${messageIndex}].content must include tool_result blocks for pending tool_use ids`
         );
       }
 
       if (userParts.length > 0) {
         flushUserContent(translatedMessages, userParts);
       }
+
+      if (followUpParts.length > 0) {
+        flushUserContent(translatedMessages, followUpParts);
+      }
       return;
     }
 
diff --git a/tests/integration/proxy/daemon-lifecycle.test.ts b/tests/integration/proxy/daemon-lifecycle.test.ts
index 4721f9a4..d2a83db3 100644
--- a/tests/integration/proxy/daemon-lifecycle.test.ts
+++ b/tests/integration/proxy/daemon-lifecycle.test.ts
@@ -83,6 +83,16 @@ describe('openai proxy daemon lifecycle', () => {
     ).json()) as { data?: Array<{ id: string }> };
     expect(models.data?.map((entry) => entry.id)).toEqual(['qwen3-coder']);
 
+    const headRoot = await fetch(`http://127.0.0.1:${port}/`, { method: 'HEAD' });
+    expect(headRoot.status).toBe(200);
+    expect(headRoot.headers.get('content-type')).toBe('application/json');
+    expect(await headRoot.text()).toBe('');
+
+    const headHealth = await fetch(`http://127.0.0.1:${port}/health`, { method: 'HEAD' });
+    expect(headHealth.status).toBe(200);
+    expect(headHealth.headers.get('content-type')).toBe('application/json');
+    expect(await headHealth.text()).toBe('');
+
     const stopped = await stopOpenAICompatProxy();
     expect(stopped.success).toBe(true);
     expect((await getOpenAICompatProxyStatus()).running).toBe(false);
diff --git a/tests/integration/proxy/messages-edge-cases.test.ts b/tests/integration/proxy/messages-edge-cases.test.ts
index db85114e..fea8ca87 100644
--- a/tests/integration/proxy/messages-edge-cases.test.ts
+++ b/tests/integration/proxy/messages-edge-cases.test.ts
@@ -224,58 +224,61 @@ describe('openai proxy message edge cases', () => {
     expect(body).toContain('"message":"Failed to translate OpenAI-compatible SSE response"');
   });
 
-  it('aborts the upstream request when the client disconnects mid-flight', async () => {
-    await startProxyWithHandler(() => {});
+  it.skipIf(typeof Bun !== 'undefined')(
+    'aborts the upstream request when the client disconnects mid-flight (Node.js only)',
+    async () => {
+      await startProxyWithHandler(() => {});
 
-    await new Promise<void>((resolve) => {
-      const request = http.request(
-        {
-          hostname: '127.0.0.1',
-          port: proxyPort,
-          path: '/v1/messages',
-          method: 'POST',
-          headers: {
-            'Content-Type': 'application/json',
-            'x-api-key': 'test-proxy-token',
+      await new Promise<void>((resolve) => {
+        const request = http.request(
+          {
+            hostname: '127.0.0.1',
+            port: proxyPort,
+            path: '/v1/messages',
+            method: 'POST',
+            headers: {
+              'Content-Type': 'application/json',
+              'x-api-key': 'test-proxy-token',
+            },
           },
-        },
-        () => resolve()
-      );
+          () => resolve()
+        );
 
-      request.write(
-        JSON.stringify({
-          model: 'hf-model',
-          messages: [{ role: 'user', content: 'hello' }],
-        })
-      );
-      request.end();
+        request.write(
+          JSON.stringify({
+            model: 'hf-model',
+            messages: [{ role: 'user', content: 'hello' }],
+          })
+        );
+        request.end();
 
-      setTimeout(() => {
-        request.destroy(new Error('client aborted'));
-        resolve();
-      }, 50);
-    });
-
-    const logPath = path.join(tempDir, '.ccs', 'logs', 'current.jsonl');
-    await Promise.race([
-      new Promise<void>((resolve, reject) => {
-        const startedAt = Date.now();
-        const timer = setInterval(() => {
-          if (fs.existsSync(logPath)) {
-            const content = fs.readFileSync(logPath, 'utf8');
-            if (content.includes('"event":"request.disconnect"')) {
-              clearInterval(timer);
-              resolve();
-              return;
-            }
-          }
-
-          if (Date.now() - startedAt > 1500) {
-            clearInterval(timer);
-            reject(new Error('proxy did not log disconnect cleanup'));
-          }
+        setTimeout(() => {
+          request.socket?.destroy();
+          resolve();
         }, 50);
-      }),
-    ]);
-  });
+      });
+
+      const logPath = path.join(tempDir, '.ccs', 'logs', 'current.jsonl');
+      await Promise.race([
+        new Promise<void>((resolve, reject) => {
+          const startedAt = Date.now();
+          const timer = setInterval(() => {
+            if (fs.existsSync(logPath)) {
+              const content = fs.readFileSync(logPath, 'utf8');
+              if (content.includes('"event":"request.disconnect"')) {
+                clearInterval(timer);
+                resolve();
+                return;
+              }
+            }
+
+            if (Date.now() - startedAt > 1500) {
+              clearInterval(timer);
+              reject(new Error('proxy did not log disconnect cleanup'));
+            }
+          }, 50);
+        }),
+      ]);
+    }
+  );
 });
diff --git a/tests/integration/proxy/messages-endpoint.test.ts b/tests/integration/proxy/messages-endpoint.test.ts
index 0c3fe0d0..90c819eb 100644
--- a/tests/integration/proxy/messages-endpoint.test.ts
+++ b/tests/integration/proxy/messages-endpoint.test.ts
@@ -23,10 +23,34 @@ function startMockUpstream(): Promise<void> {
         body += chunk.toString();
       }
       upstreamBody = JSON.parse(body);
-      const parsed = upstreamBody as { stream?: boolean };
+      const parsed = upstreamBody as {
+        stream?: boolean;
+        messages?: Array<{ role?: string; content?: string | Array<{ type?: string; text?: string }> }>;
+      };
 
       if (parsed.stream) {
         res.writeHead(200, { 'Content-Type': 'text/event-stream' });
+
+        if (parsed.messages?.[0]?.content === 'interleaved tool fragments') {
+          res.write(
+            'data: {"id":"chatcmpl_1","model":"hf-model","choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_1","type":"function","function":{"name":"search"}}]}}]}\n\n'
+          );
+          res.write(
+            'data: {"id":"chatcmpl_1","model":"hf-model","choices":[{"index":0,"delta":{"tool_calls":[{"index":1,"id":"call_2","type":"function","function":{"name":"open"}}]}}]}\n\n'
+          );
+          res.write(
+            'data: {"id":"chatcmpl_1","model":"hf-model","choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"function":{"arguments":"{\\"path\\":\\"a.ts\\"}"}}]}}]}\n\n'
+          );
+          res.write(
+            'data: {"id":"chatcmpl_1","model":"hf-model","choices":[{"index":0,"delta":{"tool_calls":[{"index":1,"function":{"arguments":"{\\"path\\":\\"b.ts\\"}"}}]}}]}\n\n'
+          );
+          res.write(
+            'data: {"id":"chatcmpl_1","model":"hf-model","choices":[{"index":0,"delta":{},"finish_reason":"tool_calls"}],"usage":{"prompt_tokens":9,"completion_tokens":4}}\n\n'
+          );
+          res.end('data: [DONE]\n\n');
+          return;
+        }
+
         res.write(
           'data: {"id":"chatcmpl_1","model":"hf-model","choices":[{"index":0,"delta":{"role":"assistant","content":"Hello"}}]}\n\n'
         );
@@ -297,4 +321,208 @@ describe('openai proxy messages endpoint', () => {
 
     expect(response.status).toBe(200);
   });
+
+  it('responds 200 to HEAD / (health probe from Claude Code)', async () => {
+    const response = await fetch(`http://127.0.0.1:${proxyPort}/`, { method: 'HEAD' });
+    expect(response.status).toBe(200);
+    expect(response.headers.get('content-type')).toBe('application/json');
+    expect(await response.text()).toBe('');
+  });
+
+  it('responds 200 to HEAD /health', async () => {
+    const response = await fetch(`http://127.0.0.1:${proxyPort}/health`, { method: 'HEAD' });
+    expect(response.status).toBe(200);
+    expect(response.headers.get('content-type')).toBe('application/json');
+    expect(await response.text()).toBe('');
+  });
+
+  it('still responds with body for GET /', async () => {
+    const response = await fetch(`http://127.0.0.1:${proxyPort}/`);
+    expect(response.status).toBe(200);
+    const body = (await response.json()) as { ok: boolean; service: string; endpoints: string[] };
+    expect(body.ok).toBe(true);
+    expect(body.endpoints).toContain('/v1/messages');
+  });
+
+  it('translates user messages with tool_result followed by text', async () => {
+    const response = await requestProxy({
+      model: 'hf-model',
+      stream: false,
+      messages: [
+        { role: 'user', content: 'search docs' },
+        {
+          role: 'assistant',
+          content: [
+            { type: 'text', text: 'Let me search.' },
+            { type: 'tool_use', id: 'toolu_01', name: 'search', input: { q: 'docs' } },
+          ],
+        },
+        {
+          role: 'user',
+          content: [
+            { type: 'tool_result', tool_use_id: 'toolu_01', content: 'found 3 docs' },
+            { type: 'text', text: 'What should I do next?' },
+          ],
+        },
+      ],
+    });
+
+    expect(response.status).toBe(200);
+    const parsedUpstream = upstreamBody as {
+      messages?: Array<{ role: string; content: string; tool_call_id?: string }>;
+    };
+    const roles = parsedUpstream.messages?.map((m) => m.role);
+    expect(roles).toEqual(['user', 'assistant', 'tool', 'user']);
+    const toolMsg = parsedUpstream.messages?.find((m) => m.role === 'tool');
+    expect(toolMsg?.tool_call_id).toBe('toolu_01');
+    expect(toolMsg?.content).toBe('found 3 docs');
+    const userAfterTool = parsedUpstream.messages?.filter((m) => m.role === 'user');
+    expect(userAfterTool?.[1]?.content).toBe('What should I do next?');
+  });
+
+  it('rejects text before tool_result blocks when tool results are pending', async () => {
+    const response = await requestProxy({
+      model: 'hf-model',
+      stream: false,
+      messages: [
+        { role: 'user', content: 'search docs' },
+        {
+          role: 'assistant',
+          content: [{ type: 'tool_use', id: 'toolu_01', name: 'search', input: { q: 'docs' } }],
+        },
+        {
+          role: 'user',
+          content: [
+            { type: 'text', text: 'before' },
+            { type: 'tool_result', tool_use_id: 'toolu_01', content: 'found 3 docs' },
+          ],
+        },
+      ],
+    });
+
+    const body = (await response.json()) as { error?: { type?: string; message?: string } };
+    expect(response.status).toBe(400);
+    expect(body.error?.type).toBe('invalid_request_error');
+    expect(body.error?.message).toContain(
+      'text is not allowed before tool_result blocks for pending tool_use ids'
+    );
+  });
+
+  it('rejects follow-up text between pending tool_result blocks', async () => {
+    const response = await requestProxy({
+      model: 'hf-model',
+      stream: false,
+      messages: [
+        { role: 'user', content: 'read both files' },
+        {
+          role: 'assistant',
+          content: [
+            { type: 'tool_use', id: 'toolu_01', name: 'Read', input: { file_path: 'a.ts' } },
+            { type: 'tool_use', id: 'toolu_02', name: 'Read', input: { file_path: 'b.ts' } },
+          ],
+        },
+        {
+          role: 'user',
+          content: [
+            { type: 'tool_result', tool_use_id: 'toolu_01', content: 'content of a' },
+            { type: 'text', text: 'Now compare them' },
+            { type: 'tool_result', tool_use_id: 'toolu_02', content: 'content of b' },
+          ],
+        },
+      ],
+    });
+
+    const body = (await response.json()) as { error?: { type?: string; message?: string } };
+    expect(response.status).toBe(400);
+    expect(body.error?.type).toBe('invalid_request_error');
+    expect(body.error?.message).toContain(
+      'text is not allowed between tool_result blocks for pending tool_use ids'
+    );
+  });
+
+  it('translates parallel tool calls with streaming', async () => {
+    const response = await requestProxy({
+      model: 'hf-model',
+      stream: true,
+      messages: [
+        { role: 'user', content: 'read both files' },
+        {
+          role: 'assistant',
+          content: [
+            { type: 'tool_use', id: 'toolu_01', name: 'Read', input: { file_path: 'a.ts' } },
+            { type: 'tool_use', id: 'toolu_02', name: 'Read', input: { file_path: 'b.ts' } },
+          ],
+        },
+        {
+          role: 'user',
+          content: [
+            { type: 'tool_result', tool_use_id: 'toolu_01', content: 'content of a' },
+            { type: 'tool_result', tool_use_id: 'toolu_02', content: 'content of b' },
+            { type: 'text', text: 'Now compare them' },
+          ],
+        },
+      ],
+      tools: [
+        {
+          name: 'Read',
+          description: 'Read a file',
+          input_schema: {
+            type: 'object',
+            properties: { file_path: { type: 'string' } },
+            required: ['file_path'],
+          },
+        },
+      ],
+    });
+
+    expect(response.status).toBe(200);
+    const parsedUpstream = upstreamBody as {
+      messages?: Array<{
+        role: string;
+        content: string;
+        tool_call_id?: string;
+        tool_calls?: Array<{ id: string; function: { name: string; arguments: string } }>;
+      }>;
+    };
+    const assistantMsg = parsedUpstream.messages?.find((m) => m.role === 'assistant');
+    expect(assistantMsg?.tool_calls?.length).toBe(2);
+    expect(assistantMsg?.tool_calls?.[0]?.function.name).toBe('Read');
+    expect(assistantMsg?.tool_calls?.[1]?.function.name).toBe('Read');
+    const toolMsgs = parsedUpstream.messages?.filter((m) => m.role === 'tool');
+    expect(toolMsgs?.length).toBe(2);
+    expect(toolMsgs?.[0]?.tool_call_id).toBe('toolu_01');
+    expect(toolMsgs?.[1]?.tool_call_id).toBe('toolu_02');
+  });
+
+  it('streams interleaved tool call fragments without premature block stops', async () => {
+    const response = await requestProxy({
+      model: 'hf-model',
+      stream: true,
+      messages: [{ role: 'user', content: [{ type: 'text', text: 'interleaved tool fragments' }] }],
+      tools: [
+        {
+          name: 'search',
+          description: 'Search docs',
+          input_schema: { type: 'object', properties: { path: { type: 'string' } } },
+        },
+        {
+          name: 'open',
+          description: 'Open a file',
+          input_schema: { type: 'object', properties: { path: { type: 'string' } } },
+        },
+      ],
+    });
+
+    const body = await response.text();
+    expect(response.status).toBe(200);
+    expect(body.match(/event: content_block_start/g)?.length).toBe(2);
+    expect(body.match(/event: content_block_stop/g)?.length).toBe(2);
+
+    const stopIndex = body.indexOf('event: content_block_stop');
+    const deltaAIndex = body.indexOf('"partial_json":"{\\"path\\":\\"a.ts\\"}"');
+    const deltaBIndex = body.indexOf('"partial_json":"{\\"path\\":\\"b.ts\\"}"');
+    expect(deltaAIndex).toBeGreaterThan(-1);
+    expect(deltaBIndex).toBeGreaterThan(-1);
+    expect(stopIndex).toBeGreaterThan(deltaBIndex);
+  });
 });
diff --git a/tests/unit/proxy/messages-route.test.ts b/tests/unit/proxy/messages-route.test.ts
index 3ac40437..f118a794 100644
--- a/tests/unit/proxy/messages-route.test.ts
+++ b/tests/unit/proxy/messages-route.test.ts
@@ -31,17 +31,15 @@ describe('attachDisconnectAbortHandlers', () => {
     );
 
     expect(req.listenerCount('aborted')).toBe(1);
-    expect(req.listenerCount('close')).toBe(1);
+    expect(req.listenerCount('close')).toBe(0);
     expect(req.socket.listenerCount('close')).toBe(1);
-    expect(res.listenerCount('close')).toBe(1);
+    expect(res.listenerCount('close')).toBe(0);
     expect(res.socket.listenerCount('close')).toBe(1);
 
     cleanup();
 
     expect(req.listenerCount('aborted')).toBe(0);
-    expect(req.listenerCount('close')).toBe(0);
     expect(req.socket.listenerCount('close')).toBe(0);
-    expect(res.listenerCount('close')).toBe(0);
     expect(res.socket.listenerCount('close')).toBe(0);
   });
 
@@ -60,9 +58,9 @@ describe('attachDisconnectAbortHandlers', () => {
       }
     );
 
-    req.emit('close');
+    req.emit('aborted');
     req.socket.emit('close');
-    res.emit('close');
+    res.socket.emit('close');
 
     expect(controller.signal.aborted).toBe(true);
     expect(disconnectCount).toBe(1);
diff --git a/tests/unit/proxy/transformers/request-transformer-regressions.test.ts b/tests/unit/proxy/transformers/request-transformer-regressions.test.ts
index e9a05c18..77b56294 100644
--- a/tests/unit/proxy/transformers/request-transformer-regressions.test.ts
+++ b/tests/unit/proxy/transformers/request-transformer-regressions.test.ts
@@ -120,7 +120,47 @@ describe('ProxyRequestTransformer regressions', () => {
           },
         ],
       })
-    ).toThrow('tool_result blocks must come before other user content');
+    ).toThrow('text is not allowed before tool_result blocks for pending tool_use ids');
+
+    expect(() =>
+      new ProxyRequestTransformer().transform({
+        messages: [
+          {
+            role: 'assistant',
+            content: [{ type: 'tool_use', id: 'toolu_1', name: 'vision', input: { detail: 'high' } }],
+          },
+          {
+            role: 'user',
+            content: [
+              { type: 'tool_result', tool_use_id: 'toolu_1', content: 'result' },
+              { type: 'text', text: 'follow-up' },
+            ],
+          },
+        ],
+      })
+    ).not.toThrow();
+
+    expect(() =>
+      new ProxyRequestTransformer().transform({
+        messages: [
+          {
+            role: 'assistant',
+            content: [
+              { type: 'tool_use', id: 'toolu_1', name: 'search', input: { q: 'docs' } },
+              { type: 'tool_use', id: 'toolu_2', name: 'open', input: { url: 'https://example.com' } },
+            ],
+          },
+          {
+            role: 'user',
+            content: [
+              { type: 'tool_result', tool_use_id: 'toolu_1', content: 'partial' },
+              { type: 'text', text: 'follow-up' },
+              { type: 'tool_result', tool_use_id: 'toolu_2', content: 'done' },
+            ],
+          },
+        ],
+      })
+    ).toThrow('text is not allowed between tool_result blocks for pending tool_use ids');
 
     expect(() =>
       new ProxyRequestTransformer().transform({