refactor(proxy): internalize sse translation and cleanup handlers

tests/unit/proxy/messages-route.test.ts

@@ -0,0 +1,72 @@
+import { describe, expect, it } from 'bun:test';
+import { EventEmitter } from 'events';
+import { attachDisconnectAbortHandlers } from '../../../src/proxy/server/messages-route';
+
+class FakeSocket extends EventEmitter {
+  destroyed = false;
+}
+
+class FakeRequest extends EventEmitter {
+  destroyed = false;
+  socket = new FakeSocket();
+}
+
+class FakeResponse extends EventEmitter {
+  destroyed = false;
+  writableEnded = false;
+  socket = new FakeSocket();
+}
+
+describe('attachDisconnectAbortHandlers', () => {
+  it('cleans up registered listeners after the request completes', () => {
+    const req = new FakeRequest();
+    const res = new FakeResponse();
+    const controller = new AbortController();
+
+    const cleanup = attachDisconnectAbortHandlers(
+      req as never,
+      res as never,
+      controller,
+      () => {}
+    );
+
+    expect(req.listenerCount('aborted')).toBe(1);
+    expect(req.listenerCount('close')).toBe(1);
+    expect(req.socket.listenerCount('close')).toBe(1);
+    expect(res.listenerCount('close')).toBe(1);
+    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);
+  });
+
+  it('aborts at most once when disconnect signals race each other', () => {
+    const req = new FakeRequest();
+    const res = new FakeResponse();
+    const controller = new AbortController();
+    let disconnectCount = 0;
+
+    const cleanup = attachDisconnectAbortHandlers(
+      req as never,
+      res as never,
+      controller,
+      () => {
+        disconnectCount += 1;
+      }
+    );
+
+    req.emit('close');
+    req.socket.emit('close');
+    res.emit('close');
+
+    expect(controller.signal.aborted).toBe(true);
+    expect(disconnectCount).toBe(1);
+
+    cleanup();
+  });
+});

tests/unit/proxy/transformers/sse-stream-transformer.test.ts

@@ -0,0 +1,70 @@
+import { describe, expect, it } from 'bun:test';
+import { createAnthropicProxyResponse } from '../../../../src/proxy/transformers/sse-stream-transformer';
+
+describe('proxy SSE stream transformer', () => {
+  it('converts OpenAI JSON into Anthropic message JSON', async () => {
+    const response = new Response(
+      JSON.stringify({
+        id: 'chatcmpl_1',
+        model: 'claude-sonnet-4.5',
+        choices: [
+          {
+            index: 0,
+            message: {
+              role: 'assistant',
+              content: 'Here is the result.',
+              reasoning_content: 'Need to call the tool first.',
+              tool_calls: [
+                {
+                  id: 'toolu_2',
+                  type: 'function',
+                  function: { name: 'search', arguments: '{"q":"proxy"}' },
+                },
+              ],
+            },
+            finish_reason: 'tool_calls',
+          },
+        ],
+        usage: { prompt_tokens: 12, completion_tokens: 4, total_tokens: 16 },
+      }),
+      {
+        status: 200,
+        headers: { 'Content-Type': 'application/json' },
+      }
+    );
+
+    const transformed = await createAnthropicProxyResponse(response);
+    const body = (await transformed.json()) as {
+      type: string;
+      stop_reason: string;
+      content: Array<{ type: string; thinking?: string; name?: string }>;
+    };
+
+    expect(body.type).toBe('message');
+    expect(body.stop_reason).toBe('tool_use');
+    expect(body.content.map((block) => block.type)).toEqual(['thinking', 'text', 'tool_use']);
+    expect(body.content[0]?.thinking).toContain('Need to call the tool first');
+    expect(body.content[2]?.name).toBe('search');
+  });
+
+  it('converts OpenAI SSE chunks into Anthropic SSE events', async () => {
+    const openAISse = [
+      'data: {"id":"chatcmpl_2","object":"chat.completion.chunk","created":1,"model":"claude-sonnet-4.5","choices":[{"index":0,"delta":{"role":"assistant","content":"Hello"},"finish_reason":null}]}\n\n',
+      'data: {"id":"chatcmpl_2","object":"chat.completion.chunk","created":1,"model":"claude-sonnet-4.5","choices":[{"index":0,"delta":{},"finish_reason":"stop"}],"usage":{"prompt_tokens":5,"completion_tokens":1,"total_tokens":6}}\n\n',
+      'data: [DONE]\n\n',
+    ].join('');
+
+    const transformed = await createAnthropicProxyResponse(
+      new Response(openAISse, {
+        status: 200,
+        headers: { 'Content-Type': 'text/event-stream' },
+      })
+    );
+
+    const body = await transformed.text();
+    expect(body).toContain('event: message_start');
+    expect(body).toContain('event: content_block_start');
+    expect(body).toContain('"type":"text_delta"');
+    expect(body).toContain('event: message_stop');
+  });
+});