v0.3.3: highlight folders by name (weak yellow)

src/main/resources/web/browser.js

@@ -317,25 +317,36 @@ function dualBrowser() {
         },
 
         /**
-         * Cross-panel file-match indicator for row highlighting (v0.3.2). Returns one of:
-         *   'match-same'       — file with the same (name, size, mtime) exists on the
-         *                        OTHER panel's current view  → subtle green tint
-         *   'match-mtime-diff' — same (name, size) but different mtime → subtle yellow
-         *                        tint (might still be the same content, but copy time
-         *                        differed; hash check would settle it definitively)
-         *   null               — no useful match, no highlight
+         * Cross-panel match indicator for row highlighting. Returns one of:
+         *   'match-same'       — file: same (name, size, mtime) exists on the OTHER
+         *                        panel's current view → subtle green
+         *   'match-mtime-diff' — file: same (name, size) but different mtime → subtle
+         *                        yellow (might be the same content with drifted mtime)
+         *                      — dir:  a directory with the same name exists on the
+         *                        other side → subtle yellow (we can't compare recursive
+         *                        size/mtime cheaply, so name-only is the strongest
+         *                        signal we offer here; v0.3.3+)
+         *   null               — no useful match
          *
-         * Only same-directory comparison: a file at /share/Movies/big.mkv on the left
-         * is NOT matched against /incoming/big.mkv on the right unless both panels are
-         * navigated to the matching directory. Dirs are never highlighted.
+         * Same-directory comparison only: navigate both panels into the matching folder
+         * to see tints. Hash-based comparison stays out of scope.
          *
          * @param side  'local' | 'peer' — which panel the row belongs to
          * @param e     entry being rendered
          */
         matchClass(side, e) {
-            if (!e || e.type !== 'file') return null;
+            if (!e) return null;
             const other = side === 'local' ? this.peer : this.local;
             if (!other) return null;
+            if (e.type === 'dir') {
+                // Dir mtime is non-recursive (only triggers on add/remove of immediate
+                // children) and the listing has no recursive size, so any "deeper" check
+                // would require a fs-walk we don't want to fire on every browse. Yellow
+                // tint = "a folder with this name exists on the other side; open both
+                // to compare contents."
+                return other.dirMatch(e.name) ? 'match-mtime-diff' : null;
+            }
+            if (e.type !== 'file') return null;
             const m = other.fileMatch(e.name);
             if (!m) return null;
             if (m.size !== e.size) return null;
@@ -610,24 +621,34 @@ function makePanel(side) {
             return this.entries.length > 0 && this.selection.length === this.entries.length;
         },
 
-        // Lazy index over file-type entries by name, used by dualBrowser.matchClass
-        // to highlight cross-panel matches (v0.3.2). Rebuilt on the first lookup
-        // after this.entries is replaced — `_indexedEntries` is the identity guard.
+        // Lazy by-type index over the panel's entries, used by dualBrowser.matchClass
+        // to highlight cross-panel matches. Rebuilt on the first lookup after
+        // this.entries is replaced — `_indexedEntries` is the identity guard.
         // O(N) build, O(1) lookups thereafter; a typical render with 200 files in
         // each panel does one rebuild per panel and 200 lookups per side, so
-        // sub-millisecond.
-        _fileIndex: null,
+        // sub-millisecond. Files and dirs live in separate maps because the match
+        // rules differ (dirs match by name only, files by name+size+mtime).
+        _entryIndex: null,
         _indexedEntries: null,
-        fileMatch(name) {
-            if (this._fileIndex == null || this._indexedEntries !== this.entries) {
-                const idx = new Map();
+        _ensureIndex() {
+            if (this._entryIndex == null || this._indexedEntries !== this.entries) {
+                const files = new Map();
+                const dirs = new Map();
                 for (const e of this.entries) {
-                    if (e && e.type === 'file') idx.set(e.name, e);
+                    if (!e) continue;
+                    if (e.type === 'file') files.set(e.name, e);
+                    else if (e.type === 'dir') dirs.set(e.name, e);
                 }
-                this._fileIndex = idx;
+                this._entryIndex = { files, dirs };
                 this._indexedEntries = this.entries;
             }
-            return this._fileIndex.get(name) || null;
+            return this._entryIndex;
+        },
+        fileMatch(name) {
+            return this._ensureIndex().files.get(name) || null;
+        },
+        dirMatch(name) {
+            return this._ensureIndex().dirs.get(name) || null;
         },
 
         selectedRelPaths() {