Restore referrer URL on lightbox close

Save location.href before pushState when opening lightbox from a
grid page, and navigate back to it on close. Direct single-post
page loads still return to the issue page.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/js/app.js

@@ -204,6 +204,7 @@
   let lbList     = [];    // current scoped post list
   let lbIdx      = -1;   // index into lbList
   let lbBuilt    = false;
+  let lbReferrer = null; // URL to return to on close
 
   function lbOpen(slug, scopedList) {
     lbList = scopedList || POSTS;
@@ -223,9 +224,15 @@
     lb.dataset.open = 'false';
     document.body.style.overflow = '';
     if (window.__ROUX_OPEN_SLUG) {
+      // Direct load of a single-post URL — go back to the issue page
       const cur = lbList[lbIdx];
       const issueId = (cur && cur.issue) || '01';
       navigate(`/issues/${issueId}/`);
+    } else if (lbReferrer) {
+      // Opened from a grid page — return to it
+      const ref = lbReferrer;
+      lbReferrer = null;
+      navigate(ref);
     }
   }
 
@@ -361,7 +368,7 @@
     const clicked = POSTS.find(p => p.slug === slug);
     const issueId = clicked ? clicked.issue : null;
     const scopedList = issueId ? POSTS.filter(p => p.issue === issueId) : POSTS;
-    // Update URL without page reload
+    lbReferrer = location.href;
     history.pushState({ slug }, '', card.href);
     lbOpen(slug, scopedList.length ? scopedList : POSTS);
   });

static/js/app.js

@@ -204,6 +204,7 @@
   let lbList     = [];    // current scoped post list
   let lbIdx      = -1;   // index into lbList
   let lbBuilt    = false;
+  let lbReferrer = null; // URL to return to on close
 
   function lbOpen(slug, scopedList) {
     lbList = scopedList || POSTS;
@@ -223,9 +224,15 @@
     lb.dataset.open = 'false';
     document.body.style.overflow = '';
     if (window.__ROUX_OPEN_SLUG) {
+      // Direct load of a single-post URL — go back to the issue page
       const cur = lbList[lbIdx];
       const issueId = (cur && cur.issue) || '01';
       navigate(`/issues/${issueId}/`);
+    } else if (lbReferrer) {
+      // Opened from a grid page — return to it
+      const ref = lbReferrer;
+      lbReferrer = null;
+      navigate(ref);
     }
   }
 
@@ -361,7 +368,7 @@
     const clicked = POSTS.find(p => p.slug === slug);
     const issueId = clicked ? clicked.issue : null;
     const scopedList = issueId ? POSTS.filter(p => p.issue === issueId) : POSTS;
-    // Update URL without page reload
+    lbReferrer = location.href;
     history.pushState({ slug }, '', card.href);
     lbOpen(slug, scopedList.length ? scopedList : POSTS);
   });