fix(userscript): keep download buttons working after result re-renders

Site handlers observed a replaceable container node (e.g. the pack table's
parent on xdcc.info). When a filter such as "language" re-rendered the
results, the observer kept watching a detached node and injected buttons
never came back until a full reload.

Observe document.body in all dynamic-site handlers so the observer
survives container replacement, re-query .results inside processRocksTable
for the same reason, and guard observer callbacks against firing during
page teardown.

Bump userscript version to 2026-09-20-1.

Author: luni

tests/js/userscript/xdcc-info.test.js

@@ -79,6 +79,32 @@ describe("userscript on www.xdcc.info", () => {
     });
   });
 
+  test("re-injects buttons when the results container is replaced", async () => {
+    // The language filter re-renders the whole results container, detaching
+    // the node the observer was watching.
+    document.body.innerHTML = `
+      <div class="results"><table class="pack-table"><tbody>
+        ${ROW("BotA", "1", "irc.rizon.net", "#chan")}
+      </tbody></table></div>`;
+    loadScript();
+    expect(dccbotButtons()).toHaveLength(1);
+
+    document.querySelector(".results").outerHTML = `
+      <div class="results"><table class="pack-table"><tbody>
+        ${ROW("NewBot", "42", "irc.abjects.net", "#beast-xdcc")}
+      </tbody></table></div>`;
+    await new Promise((r) => setTimeout(r, 0));
+
+    const buttons = dccbotButtons();
+    expect(buttons).toHaveLength(1);
+    expect(buttons[0].dataset).toMatchObject({
+      server: "irc.abjects.net",
+      channel: "#beast-xdcc",
+      bot: "NewBot",
+      pack: "42",
+    });
+  });
+
   test("runs on the bare xdcc.info domain too", () => {
     // hostname is fixed by the environment URL; covered by the dispatch table
     // indirectly — see hostHandlers for 'xdcc.info'.

userscript/add-dccbot-btn.js

@@ -2,7 +2,7 @@
 // @name         add-dccbot-btn
 // @namespace    https://github.com/luni/dccbot/
 // @website      https://github.com/luni/dccbot/
-// @version      2026-09-20
+// @version      2026-09-20-1
 // @description  Add button for DCCbot to automate downloads.
 // @author       luni
 // @match        https://www.xdcc.eu/search.php*
@@ -139,7 +139,11 @@
 
     function observeMutations(target, onMutation, options) {
         if (!target) return null;
-        const observer = new MutationObserver(onMutation);
+        const observer = new MutationObserver(function () {
+            // Queued callbacks can fire during page unload/teardown.
+            if (typeof document === "undefined" || !document.body) return;
+            onMutation();
+        });
         observer.observe(target, options || { childList: true, subtree: true });
         return observer;
     }
@@ -891,7 +895,9 @@
                 return;
             }
 
-            observeMutations(tableBody, scheduleProcess);
+            // Observe <body>: the results table may be replaced on re-render,
+            // which would leave an observer on a detached node dead.
+            observeMutations(document.body, scheduleProcess);
             scheduleProcess();
         }
 
@@ -945,11 +951,11 @@
     }
 
     function add_button_xdcc_rocks() {
-        const resultsRoot = document.querySelector('.results');
-        if (!resultsRoot) return;
-
-        observeMutations(resultsRoot, function () {
-            if (resultsRoot.querySelector('tr.font2_bg0_bg1')) {
+        // Observe <body>: the results container may be replaced on re-render,
+        // which would leave an observer on a detached node dead.
+        observeMutations(document.body, function () {
+            const resultsRoot = document.querySelector('.results');
+            if (resultsRoot && resultsRoot.querySelector('tr.font2_bg0_bg1')) {
                 processRocksTable();
             }
         });
@@ -992,7 +998,8 @@
         }
 
         function processRocksTable() {
-            const table = resultsRoot.querySelector('table');
+            const resultsRoot = document.querySelector('.results');
+            const table = resultsRoot ? resultsRoot.querySelector('table') : null;
             if (!table) return;
 
             let currentServer = null;
@@ -1107,8 +1114,9 @@
 
         processCards();
 
-        const resultsContainer = document.querySelector(".results-container");
-        observeMutations(resultsContainer || document.body, processCards);
+        // Observe <body>: the results container may be replaced on re-render,
+        // which would leave an observer on a detached node dead.
+        observeMutations(document.body, processCards);
     }
 
     function add_button_xdcc_info() {
@@ -1129,8 +1137,10 @@
 
         processInfoRows();
 
-        const table = document.querySelector('table.pack-table');
-        observeMutations((table && table.parentElement) || document.body, processInfoRows);
+        // Observe <body>: the pack table is replaced when filters (e.g.
+        // language) re-render, which would leave an observer on a detached
+        // node dead.
+        observeMutations(document.body, processInfoRows);
     }
 
     function add_button_skullxdcc() {
@@ -1170,8 +1180,9 @@
         }
 
         processSkullRows();
-        const wrapper = document.querySelector('.results-wrapper');
-        observeMutations(wrapper || document.body, processSkullRows);
+        // Observe <body>: the results wrapper may be replaced on re-render,
+        // which would leave an observer on a detached node dead.
+        observeMutations(document.body, processSkullRows);
     }
 
     const hostHandlers = {