refactor(browse): remove dead code, document state shape

Pure cleanup, no behavior change:

- tree.js: drop the unused setSort() method (only setSortExplicit is wired,
  via the toolbar dropdown) and its doubly-stale comment (claimed there was
  no sort UI — there is).
- app.js: remove the augmentRoot/passThroughEntries identity stub. It was a
  leftover from when browse merged virtual canonical folders client-side;
  zddc-server emits them now and nothing reads window.app.modules.augmentRoot.
- loader.js: splitExt now delegates to window.zddc.splitExtension (identical
  behavior — lowercased, dotfile/trailing-dot → '') per the CLAUDE.md rule
  that extension handling goes through window.zddc; drop the unused export.
- upload.js: remove the dead `else if (refreshUrl)` comment-only branch (and
  the unused refreshUrl var) — refreshListing is always present since it was
  exported.
- init.js: declare scopeCanonicalFolder, scopeOnPlanReview, and showHidden in
  the state initializer. They were read/written across modules but never
  listed in the canonical state shape (implicit undefined).

All 6 browse Playwright specs pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

browse/js/app.js

@@ -8,17 +8,6 @@
     var tree = window.app.modules.tree;
     var events = window.app.modules.events;
 
-    // Virtual canonical folder injection used to live here (browse
-    // appended archive/working/staging/reviewing entries at a project
-    // root when missing). zddc-server now emits them in the listing
-    // directly so the .zddc `display:` map can override their labels
-    // the same as real entries. This pass-through stub keeps the
-    // events.js rescope contract intact without doing any merging.
-    function passThroughEntries(entries) { return entries; }
-
-    // Expose for events.js's client-side rescope on dblclick.
-    window.app.modules.augmentRoot = passThroughEntries;
-
     // Walk a `?file=` path segment-by-segment from the current root.
     // Each non-leaf segment is matched against the parent's children
     // by name; if found and it's a folder, expand+load it (so its

browse/js/init.js

@@ -69,8 +69,19 @@
         //   scopeDropTarget: cascade's drop_target at currentPath
         //   scopeDefaultTool: cascade's default_tool at currentPath
         //                     (empty when no default declared)
+        //   scopeCanonicalFolder: cascade's canonical-folder slot
+        //                     ('incoming'|'received'|'working'|'staging'|…),
+        //                     drives scope-aware menu items
+        //   scopeOnPlanReview: cascade above has an on_plan_review block
+        // All refreshed by loader.js from response headers on each fetch.
         scopeDropTarget: false,
         scopeDefaultTool: '',
+        scopeCanonicalFolder: '',
+        scopeOnPlanReview: false,
+
+        // Whether the listing includes dotfiles. Toggled by the
+        // "Show hidden files" menu item; URL-persisted via ?hidden=1.
+        showHidden: false,
 
         // Autofilter — when non-empty, the tree hides files that
         // don't match and folders whose subtree has no matches.

browse/js/loader.js

@@ -11,10 +11,12 @@
 
     var state = window.app.state;
 
+    // Lowercased extension (no leading dot), '' for dotfiles / no-ext /
+    // trailing-dot names. Delegates to the shared parser so the rule
+    // stays in one place (CLAUDE.md: all extension handling goes through
+    // window.zddc).
     function splitExt(name) {
-        var i = name.lastIndexOf('.');
-        if (i <= 0 || i === name.length - 1) return '';
-        return name.substring(i + 1).toLowerCase();
+        return window.zddc.splitExtension(name).extension;
     }
 
     // Build a raw entry from the server's FileInfo shape.
@@ -222,7 +224,6 @@
         fetchServerChildren: fetchServerChildren,
         fetchFsChildren: fetchFsChildren,
         autoDetectServerMode: autoDetectServerMode,
-        splitExt: splitExt,
         ensureJSZip: ensureJSZip
     };
 })();

browse/js/tree.js

@@ -460,10 +460,6 @@
         el.innerHTML = html;
     }
 
-    // Sort headers no longer exist in the DOM (the tree replaced the
-    // table); the tree.setSort() method still works but only via
-    // programmatic callers — there's no UI for changing sort yet.
-
     // True when this .zip node lives inside another zip, so its bytes
     // can't be fetched as a standalone server resource: we read them
     // through the containing handle (offline / nested) or by fetching
@@ -690,15 +686,6 @@
         loadChildren: loadChildren,
         snapshotState: snapshotState,
         restoreState: restoreState,
-        setSort: function (key) {
-            if (state.sort.key === key) {
-                state.sort.dir = -state.sort.dir;
-            } else {
-                state.sort.key = key;
-                state.sort.dir = 1;
-            }
-            render();
-        },
         // Set both key and direction explicitly. dir: 1 (asc) or -1 (desc).
         // Used by the toolbar's sort dropdown.
         setSortExplicit: function (key, dir) {

browse/js/upload.js

@@ -286,20 +286,11 @@
             if (lastResolved) msg += ' — last at ' + lastResolved;
             note(msg, 'success');
         }
-        // Reload the listing of the workflow folder so the new +Cn file
-        // appears in the tree. The workflow folder is the parent of the
-        // virtual `received/` (i.e., the URL with one `/received/<file>`
-        // suffix stripped).
-        var refreshUrl = targetURL.replace(/\/received\/[^/]+\/?$/, '/');
+        // Reload the current listing so the new +Cn file appears in the
+        // tree. Best-effort.
         try {
             var ev = window.app.modules.events;
-            if (ev && typeof ev.refreshListing === 'function') {
-                ev.refreshListing();
-            } else if (refreshUrl) {
-                // Best-effort fallback: re-navigate to the workflow folder
-                // so its listing is refreshed.
-                // (No action — refreshListing absence implies older browse.)
-            }
+            if (ev && typeof ev.refreshListing === 'function') ev.refreshListing();
         } catch (_e) { /* refresh is best-effort */ }
     }