mindspace: close authority boundaries

mindspace-public-page-context.mjs

@@ -19,13 +19,19 @@ export function buildPublishedHtmlViewContext({
   origin = '',
   requestPath = '',
   filePath = '',
+  servedName = '',
+  fallbackImageName = '',
   thumbnailPngPathForSvg = (value) => value,
   fileExists = fs.existsSync,
 } = {}) {
   const cleanPath = String(requestPath ?? '').split('?')[0].split('#')[0];
-  const servedName = path.basename(String(filePath ?? ''));
+  const resolvedServedName =
+    String(servedName ?? '').trim() ||
+    path.basename(String(filePath ?? ''));
   const urlLast = decodeURIComponent(cleanPath.split('/').filter(Boolean).pop() ?? '');
-  const isImplicitIndex = urlLast.toLowerCase() !== servedName.toLowerCase();
+  const isImplicitIndex =
+    urlLast.toLowerCase() !==
+    resolvedServedName.toLowerCase();
   const pageUrl = !origin
     ? ''
     : `${origin}${isImplicitIndex && !cleanPath.endsWith('/') ? `${cleanPath}/` : cleanPath}`;
@@ -36,8 +42,12 @@ export function buildPublishedHtmlViewContext({
       : `${origin}${cleanPath.slice(0, cleanPath.lastIndexOf('/') + 1)}`;
 
   let fallbackImageUrl = '';
+  const logicalFallbackName =
+    String(fallbackImageName ?? '').trim();
   const svgSibling = String(filePath ?? '').replace(/\.[^./]+$/, '.thumbnail.svg');
-  if (pageDirUrl && fileExists(svgSibling)) {
+  if (pageDirUrl && logicalFallbackName) {
+    fallbackImageUrl = `${pageDirUrl}${encodeURIComponent(logicalFallbackName)}`;
+  } else if (pageDirUrl && fileExists(svgSibling)) {
     const pngName = path.basename(thumbnailPngPathForSvg(svgSibling));
     fallbackImageUrl = `${pageDirUrl}${pngName}`;
   }