fix(compare): reject incomplete and errored SSE responses

2026-11-01 10:42:23 +01:00 · 2026-10-28 13:09:35 +03:00
parent 57a1859f08
commit 5c738a5a8e
4 changed files with 149 additions and 23 deletions
@@ -0,0 +1,65 @@
+function streamError(payload) {
+  const detail = payload?.data ?? payload;
+  const candidates = [detail?.message, detail?.text, detail?.error?.message,
+    detail?.error, payload?.message, payload?.text, payload?.error?.message,
+    payload?.error, typeof payload === 'string' ? payload : null];
+  const message = candidates.find(value => typeof value === 'string' && value.trim());
+  return new Error(message || 'Model request failed.');
+}
+
+/** Decode complete SSE frames, requiring the backend's terminal DONE event. */
+export async function consumeCompareEvents(response, onEvent, onActivity) {
+  const reader = response.body.getReader();
+  const decoder = new TextDecoder();
+  let line = '', event = 'message', data = [], skipLF = false;
+  try {
+    while (true) {
+      const { done, value } = await reader.read();
+      if (!done) onActivity?.();
+      let chunk = decoder.decode(value, { stream: !done });
+      if (skipLF && chunk.length) {
+        if (chunk.startsWith('\n')) chunk = chunk.slice(1);
+        skipLF = false;
+      }
+      const separators = /\r\n|\r|\n/g;
+      let start = 0, separator;
+      while ((separator = separators.exec(chunk))) {
+        line += chunk.slice(start, separator.index);
+        start = separator.index + separator[0].length;
+        skipLF = separator[0] === '\r' && start === chunk.length;
+        if (!line) {
+          if (data.length || event === 'error') {
+            const raw = data.join('\n');
+            if (event !== 'error' && raw === '[DONE]') return;
+            let payload;
+            try { payload = JSON.parse(raw); }
+            catch (_) {
+              if (event === 'error') throw streamError(raw);
+              throw new Error('Invalid model stream data.');
+            }
+            if (event === 'error' || payload?.type === 'error') throw streamError(payload);
+            if (!payload || typeof payload !== 'object' || Array.isArray(payload)) {
+              throw new Error('Invalid model stream data.');
+            }
+            await onEvent(payload);
+          }
+          event = 'message';
+          data = [];
+        } else if (!line.startsWith(':')) {
+          const colon = line.indexOf(':');
+          const field = colon < 0 ? line : line.slice(0, colon);
+          let value = colon < 0 ? '' : line.slice(colon + 1);
+          if (value.startsWith(' ')) value = value.slice(1);
+          if (field === 'data') data.push(value);
+          else if (field === 'event') event = value || 'message';
+        }
+        line = '';
+      }
+      line += chunk.slice(start);
+      if (done) throw new Error('Stream ended before completion.');
+    }
+  } finally {
+    try { await reader.cancel(); } catch (_) {}
+    reader.releaseLock();
+  }
+}