chore: import upstream snapshot with attribution

evals/src/source.ts

@@ -0,0 +1,34 @@
+export function extractZeroSource(text: string): string {
+  const fenced = text.match(/```(?:zero|0)?\s*([\s\S]*?)```/i);
+  const source = fenced ? fenced[1] : extractUnfencedZeroSource(text);
+  return `${source.trim()}\n`;
+}
+
+export function sourcePatternFailures(
+  source: string,
+  patterns: RegExp[],
+): string[] {
+  return patterns
+    .filter((pattern) => !pattern.test(source))
+    .map((pattern) => pattern.toString());
+}
+
+const ZERO_SOURCE_START_PATTERN =
+  /^\s*(?:(?:pub\s+)?(?:export\s+c\s+fn|extern\s+(?:c|type)|packed\s+type|fn|const|type|enum|choice|alias|interface)\s+|use\s+|test\s+)/;
+
+export function finalSourceResponseFailures(
+  responseText: string,
+  source: string,
+): string[] {
+  if (!ZERO_SOURCE_START_PATTERN.test(source.trim())) {
+    return ["final response did not include Zero source"];
+  }
+  return [];
+}
+
+function extractUnfencedZeroSource(text: string) {
+  const lines = text.split(/\r?\n/);
+  const start = lines.findIndex((line) => ZERO_SOURCE_START_PATTERN.test(line));
+  if (start === -1) return text;
+  return lines.slice(start).join("\n");
+}