fix(tables): handle bare-directory URLs served as default_tool

Visiting `/Project-1/archive/PartyA/mdl` (no trailing slash) errored with
`Unrecognized table URL` because tableNameFromUrl only matched
`…/<rowsdir>/table.html`. The cascade declares `default_tool: tables` at
`archive/<party>/mdl`, so the server serves the tables HTML at the bare
directory URL — a shape the client didn't recognize.

Two coordinated fixes:

- shared/zddc-source.js `pathToDir`: was over-eagerly stripping the last
  segment when the URL didn't end in `/`. Now checks whether the last
  segment contains a dot — file URLs strip to parent (original behavior
  preserved), bare-directory URLs append the missing slash. Only call
  site is detectServerRoot, so blast radius is contained.
- tables/js/context.js `tableNameFromUrl` + `rowEditUrl`: accept both
  legacy `…/<rowsdir>/table.html` and the new bare-directory shape.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

shared/zddc-source.js

@@ -289,13 +289,33 @@
     // Top-level helpers
     // -----------------------------------------------------------------
 
-    // Strip a trailing tool .html (e.g. classifier.html) from a path
+    // Resolve "the directory the tool was opened in" for the current
-    // to land on the "directory the tool was opened in".
+    // page URL. Two URL shapes serve a tool:
+    //
+    //   /…/<tool>.html        — file URL; strip the trailing filename.
+    //   /…/<dir>/             — trailing-slash directory URL; keep it.
+    //   /…/<dir>              — bare-directory URL served by the
+    //                           cascade's `default_tool` (e.g.
+    //                           archive/<party>/mdl serves the tables
+    //                           tool). Treat as the directory itself
+    //                           and append the missing slash.
+    //
+    // Discrimination is "does the last segment contain a dot?" — a dot
+    // is a reliable proxy for "looks like a file with an extension"
+    // since neither directory names nor default_tool paths contain
+    // them in this system.
     function pathToDir(pathname) {
         if (!pathname) return '/';
         if (pathname.endsWith('/')) return pathname;
         var slash = pathname.lastIndexOf('/');
-        return slash >= 0 ? pathname.substring(0, slash + 1) : '/';
+        var lastSeg = slash >= 0 ? pathname.substring(slash + 1) : pathname;
+        if (lastSeg.indexOf('.') !== -1) {
+            // Has an extension → looks like a file URL → strip the
+            // filename to land on the parent directory.
+            return slash >= 0 ? pathname.substring(0, slash + 1) : '/';
+        }
+        // No extension → the URL IS the directory; just close it.
+        return pathname + '/';
     }
 
     // Probe the server-mode root for the current page. Returns:

tables/js/context.js

@@ -117,10 +117,20 @@
     }
 
     function tableNameFromUrl(pathname) {
-        // /<dir>/.../<rowsdir>/table.html → name is the rows-dir's
+        // Two URL shapes resolve to a table page:
-        // basename.
+        //   Form A — /<…>/<rowsdir>/table.html (legacy/explicit
-        const m = String(pathname || '').match(/\/([^\/]+)\/table\.html$/);
+        //            entry-point; the tool was opened via the
-        return m ? m[1] : null;
+        //            literal file URL).
+        //   Form B — /<…>/<rowsdir>  or  /<…>/<rowsdir>/  (served
+        //            by the cascade's `default_tool: tables` at
+        //            archive/<party>/mdl; the URL is the directory
+        //            itself, no trailing filename).
+        // In both cases the table name is the rows-directory basename.
+        const a = String(pathname || '').match(/\/([^\/]+)\/table\.html$/);
+        if (a) return a[1];
+        const trimmed = String(pathname || '').replace(/\/$/, '');
+        const b = trimmed.match(/\/([^\/]+)$/);
+        return b ? b[1] : null;
     }
 
     function stripDotSlash(p) {
@@ -198,11 +208,13 @@
         return rows;
     }
 
-    // Re-edit URL for one row. Page is at /<dir>/table.html; row file
+    // Re-edit URL for one row. The page directory is the same
-    // lives at /<dir>/<basename>.yaml; form re-edit URL is
+    // directory the rows live in, regardless of which URL shape
-    // /<dir>/<basename>.yaml.html — same directory.
+    // (Form A `…/table.html` vs Form B bare `…/<rowsdir>`) we were
+    // opened with — see tableNameFromUrl.
     function rowEditUrl(rowFileName) {
-        const pageDir = location.pathname.replace(/\/table\.html$/, '/');
+        let pageDir = location.pathname.replace(/\/table\.html$/, '/');
+        if (!pageDir.endsWith('/')) pageDir += '/';
         return pageDir + rowFileName + '.html';
     }