Make inline region dropdown keyboard-operable and harden role parser

region-selector.js: the inline dropdown was mouse-only — every option
had tabIndex=-1 and only a click handler. Add a standard listbox
keyboard contract:

  - Tab focuses the trigger; ArrowDown / Enter / Space opens the menu
    and focuses the active option (ArrowUp opens at the last option)
  - Inside the open menu: ArrowDown/ArrowUp move focus, Home/End jump
    to first/last, Enter/Space select, Escape closes and returns
    focus to the trigger, Tab closes and lets the browser advance
  - Roving tabindex: the focused option holds tabIndex=0, the rest -1,
    so the menu participates correctly in the page's tab order
  - Selection closes the menu, restores focus to the trigger, and
    flows through the existing syncAll() so every other region
    selector updates in lock-step

region_box.py: defensive fallback in robusta_url_role so an
empty-after-strip label can never produce an empty anchor — if the
label half ends up blank, fall back to the URL as link text. Today's
regex can't actually emit an empty label, but the guard makes a
future regex tweak safe.

Author: claude

docs/_ext/region_box.py

@@ -116,6 +116,8 @@ def robusta_url_role(name, rawtext, text, lineno, inliner, options=None, content
     else:
         url = raw_text.strip()
         label = url
+    if not label:
+        label = url
     if not url:
         msg = inliner.reporter.error(
             "robusta-url role requires a URL", line=lineno

docs/_static/region-selector.js

@@ -144,34 +144,103 @@
     menu.setAttribute("role", "listbox");
 
     const items = [];
+
+    function focusItem(idx) {
+      if (idx < 0) idx = items.length - 1;
+      if (idx >= items.length) idx = 0;
+      items.forEach(function (it, i) { it.tabIndex = i === idx ? 0 : -1; });
+      items[idx].focus();
+    }
+
+    function selectItem(key) {
+      syncAll(key);
+      picker.classList.remove("is-open");
+      trigger.setAttribute("aria-expanded", "false");
+      trigger.focus();
+    }
+
     Object.keys(REGIONS).forEach(function (key) {
       const item = document.createElement("li");
       item.setAttribute("role", "option");
       item.setAttribute("data-region", key);
       item.className = "robusta-region-inline__option";
-      item.tabIndex = -1;
       const isActive = key === currentRegion;
       item.setAttribute("aria-selected", String(isActive));
+      item.tabIndex = isActive ? 0 : -1;
       if (isActive) item.classList.add("is-active");
       item.textContent = REGIONS[key].label;
       item.addEventListener("click", function (e) {
         e.preventDefault();
-        syncAll(key);
-        picker.classList.remove("is-open");
-        trigger.setAttribute("aria-expanded", "false");
-        trigger.focus();
+        selectItem(key);
+      });
+      item.addEventListener("keydown", function (e) {
+        const idx = items.indexOf(item);
+        switch (e.key) {
+          case "Enter":
+          case " ":
+            e.preventDefault();
+            selectItem(key);
+            break;
+          case "ArrowDown":
+            e.preventDefault();
+            focusItem(idx + 1);
+            break;
+          case "ArrowUp":
+            e.preventDefault();
+            focusItem(idx - 1);
+            break;
+          case "Home":
+            e.preventDefault();
+            focusItem(0);
+            break;
+          case "End":
+            e.preventDefault();
+            focusItem(items.length - 1);
+            break;
+          case "Tab":
+            picker.classList.remove("is-open");
+            trigger.setAttribute("aria-expanded", "false");
+            break;
+          case "Escape":
+            e.preventDefault();
+            picker.classList.remove("is-open");
+            trigger.setAttribute("aria-expanded", "false");
+            trigger.focus();
+            break;
+        }
       });
       menu.appendChild(item);
       items.push(item);
     });
 
+    function openMenu() {
+      closeAllInlineMenus(picker);
+      picker.classList.add("is-open");
+      trigger.setAttribute("aria-expanded", "true");
+      const activeIdx = items.findIndex(function (it) { return it.classList.contains("is-active"); });
+      focusItem(activeIdx >= 0 ? activeIdx : 0);
+    }
+
     trigger.addEventListener("click", function (e) {
       e.preventDefault();
       e.stopPropagation();
-      const willOpen = !picker.classList.contains("is-open");
-      closeAllInlineMenus(willOpen ? picker : null);
-      picker.classList.toggle("is-open", willOpen);
-      trigger.setAttribute("aria-expanded", String(willOpen));
+      if (picker.classList.contains("is-open")) {
+        picker.classList.remove("is-open");
+        trigger.setAttribute("aria-expanded", "false");
+      } else {
+        openMenu();
+      }
+    });
+
+    trigger.addEventListener("keydown", function (e) {
+      if (e.key === "ArrowDown" || e.key === "Enter" || e.key === " ") {
+        e.preventDefault();
+        openMenu();
+      } else if (e.key === "ArrowUp") {
+        e.preventDefault();
+        openMenu();
+        focusItem(items.length - 1);
+      }
     });
 
     picker.appendChild(trigger);