fix(compare): reject incomplete and errored SSE responses

tests/test_compare_stream_contract_browser.py

@@ -0,0 +1,70 @@
+"""Compare's actual stream consumer must preserve evidence and terminal state."""
+import json
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[1]
+
+CASES = [
+    ("lf", 'data: {"delta":"Hello"}\n\ndata: [DONE]\n\n', False, True, "Hello"),
+    ("crlf", 'data:{"delta":"Héllö"}\r\n\r\ndata:[DONE]\r\n\r\n', False, True, "Héllö"),
+    ("multiline", 'data: {"delta":\ndata: "Hello"}\n\ndata: [DONE]\n\n', False, True, "Hello"),
+    ("eof", 'data: {"delta":"Partial"}\n\n', False, False, "ended before completion"),
+    ("named-error", 'event: error\ndata: {"text":"Provider Z private-model failed"}\n\n', False, False, "Provider Z private-model failed"),
+    ("typed-error", 'data: {"type":"error","data":{"message":"Provider Z <img src=x onerror=alert(1)>"}}\n\ndata: [DONE]\n\n', False, False, "Provider Z <img"),
+    ("blind-error", 'event:error\ndata:{"message":"Provider Z private-model failed"}\n\n', True, False, "request failed"),
+    ("empty-error", 'event:error\ndata:\n\n', False, False, "request failed"),
+    ("done-open", 'data: {"delta":"Hello"}\n\ndata: [DONE]\n\n', False, True, "Hello"),
+    ("heartbeat", 'data: {"delta":"Hello"}\n\ndata: [DONE]\n\n', False, True, "Hello"),
+    ("cr", 'data: {"delta":"Hello"}\r\rdata:[DONE]\r\r', False, True, "Hello"),
+    ("invalid", 'data: not-json\n\ndata: [DONE]\n\n', False, False, "Invalid model stream data"),
+]
+
+
+@pytest.mark.parametrize("kind,wire,blind,success,text", CASES)
+def test_compare_stream_contract(kind, wire, blind, success, text):
+    if not shutil.which("node"):
+        pytest.skip("node not installed")
+    script = r"""
+const assert=require('node:assert/strict');
+let chromium;try{({chromium}=require('playwright'));}catch(e){if(e.code==='MODULE_NOT_FOUND')process.exit(77);throw e;}
+(async()=>{
+ const browser=await chromium.launch({headless:true});
+ try{
+  const page=await browser.newPage();
+  await page.goto(process.env.ODYSSEUS_TEST_STATIC_ORIGIN+'/static/js/storage.js');
+  await page.setContent('<div class="compare-pane" data-pane="0"><div id="cmp-badge-0"></div><div id="cmp-history-0"><div class="msg msg-ai"><div class="body"></div></div></div></div>');
+  const result=await page.evaluate(async(data)=>{
+   const {default:state}=await import('/static/js/compare/state.js');
+   const {streamToPane}=await import('/static/js/compare/stream.js');
+   Object.assign(state,{isActive:true,_selectedModels:[{model:'fixture',name:'Fixture'}],_paneSessionIds:['session'],_compareMode:'chat',_parallel:true,_blindMode:data.blind,_timeout:data.kind==='heartbeat'?1:5});
+   const nativeFetch=window.fetch,bytes=new TextEncoder().encode(data.wire);let index=0,cancelled=false,context=null;
+   window.fetch=async(url,options)=>{
+    if(!String(url).endsWith('/api/chat_stream'))return nativeFetch(url,options);
+    context=options.body.get('search_context');
+    const heartbeats=[...Array(6).fill(': ping\n\n'),data.wire];
+    return new Response(new ReadableStream({start(controller){options.signal.addEventListener('abort',()=>controller.error(new DOMException('Stopped','AbortError')),{once:true});},async pull(controller){if(data.kind==='heartbeat'){if(index<heartbeats.length){await new Promise(r=>setTimeout(r,200));controller.enqueue(new TextEncoder().encode(heartbeats[index++]));}else controller.close();}else if(index<bytes.length)controller.enqueue(bytes.slice(index,index+=1));else if(data.kind!=='done-open')controller.close();},cancel(){cancelled=true;}}),{headers:{'Content-Type':'text/event-stream'}});
+   };
+   const message=document.querySelector('.msg-ai'),spinner=document.createElement('span');let spinnerDestroyed=false;spinner.textContent='Loading';message.querySelector('.body').appendChild(spinner);message._spinner={element:spinner,destroy(){spinnerDestroyed=true;spinner.remove();}};
+   await Promise.race([streamToPane(0,'session','Prompt',message,{skipBadge:true}),new Promise((_,reject)=>setTimeout(()=>reject(Error('Consumer did not finish at DONE')),data.kind==='heartbeat'?6000:1500))]);
+   const pane=document.querySelector('.compare-pane');
+   return {done:pane.classList.contains('is-done'),failed:pane.classList.contains('is-failed'),text:pane.innerText,images:pane.querySelectorAll('img').length,cancelled,spinnerDestroyed,spinnerOwned:!!message._spinner};
+  },JSON.parse(process.argv[1]));
+  const expected=JSON.parse(process.argv[1]);
+  assert.equal(result.done,expected.success);assert.equal(result.failed,!expected.success);assert(result.text.includes(expected.text),JSON.stringify(result));assert.equal(result.images,0);
+  assert(result.spinnerDestroyed);assert(!result.spinnerOwned);
+  if(expected.blind)assert(!/Provider Z|private-model/.test(result.text),JSON.stringify(result));
+  if(expected.kind==='done-open')assert(result.cancelled);
+  console.log(JSON.stringify(result));
+ }finally{await browser.close();}
+})().catch(e=>{console.error(e);process.exitCode=1;});
+"""
+    data = dict(kind=kind, wire=wire, blind=blind, success=success, text=text)
+    result = subprocess.run(["node", "-e", script, json.dumps(data)], cwd=ROOT,
+                            capture_output=True, text=True, timeout=30)
+    if result.returncode == 77:
+        pytest.skip("playwright not installed")
+    assert result.returncode == 0, result.stdout + result.stderr