fix(pr-to-video): enforce offline frame contract (#2383)

* fix(pr-to-video): enforce offline frame contract * fix(pr-to-video): tighten frame attribute contract
2026-09-12 15:20:13 +00:00 · 2026-07-13 22:39:32 -04:00
parent fba5cb9c93
commit 852d1891d3
16 changed files with 588 additions and 8 deletions
@@ -0,0 +1,54 @@
+function fail(message) {
+  throw new Error(`frame contract: ${message}`);
+}
+
+function attrValue(attrs, name) {
+  const match = attrs.match(
+    new RegExp(`(?:^|\\s)${name}\\s*=\\s*(?:"([^"]*)"|'([^']*)'|([^\\s"'=<>\`]+))`, "i"),
+  );
+  return match ? (match[1] ?? match[2] ?? match[3]) : null;
+}
+
+export function validateFrameHtml(html, { expectedId, expectedDuration } = {}) {
+  const source = String(html ?? "");
+  const trimmed = source.trim();
+  if (/<!doctype|<\/?(?:html|head|body)\b/i.test(trimmed)) {
+    fail("worker output must be one bare <template> fragment, not a full HTML document");
+  }
+  const opens = trimmed.match(/<template\b/gi) ?? [];
+  const closes = trimmed.match(/<\/template\s*>/gi) ?? [];
+  if (opens.length !== 1 || closes.length !== 1 || !/^<template\b/i.test(trimmed)) {
+    fail("worker output must contain exactly one bare <template> fragment");
+  }
+  if (!/<\/template\s*>$/i.test(trimmed)) {
+    fail("markup outside the closing </template> is not allowed");
+  }
+
+  const templateOpen = trimmed.match(/^<template\b[^>]*>/i)?.[0];
+  if (!templateOpen) fail("template opening tag is malformed");
+  const inner = trimmed.slice(
+    templateOpen.length,
+    trimmed.toLowerCase().lastIndexOf("</template>"),
+  );
+  const root = inner.match(/^\s*<([A-Za-z][\w:-]*)\b((?:[^>"']|"[^"]*"|'[^']*')*)>/);
+  if (!root) fail("template must begin with one composition root element");
+  const attrs = root[2];
+  const compositionId = attrValue(attrs, "data-composition-id");
+  if (!compositionId) fail("composition id is missing on the template root");
+  if (expectedId && compositionId !== expectedId) {
+    fail(`composition id ${JSON.stringify(compositionId)} does not match expected ${expectedId}`);
+  }
+
+  const durationRaw = attrValue(attrs, "data-duration");
+  const decimalDuration = /^(?:\d+(?:\.\d+)?|\.\d+)$/.test(durationRaw ?? "");
+  const duration = Number(durationRaw);
+  if (!decimalDuration || !Number.isFinite(duration) || duration <= 0) {
+    fail("root must declare a positive data-duration");
+  }
+  // Transition injection may extend an outgoing frame beyond its storyboard duration.
+  // A shorter root is always invalid; a longer root remains safe to reassemble.
+  if (Number.isFinite(expectedDuration) && duration < Number(expectedDuration) - 0.001) {
+    fail(`root duration ${duration}s is shorter than expected ${expectedDuration}s`);
+  }
+  return { compositionId, duration };
+}