Recover from a job killed by a deploy, and show when a cut reorders

cuts_state is set before the thread starts and cleared when it finishes, so
a deploy in between left the page waiting forever on work that was no longer
running, with the retry button hidden. Fifteen minutes is longer than the
work can legitimately take.

A cut may reorder as well as drop, which changes what it is - worth saying
rather than leaving the reader to spot it in the id list.

trailer.html

@@ -332,7 +332,7 @@
           + 'Each other model reads ONLY this script - no book - and says what it understood.">'
           + (REVIEWS.length ? "Test it again" : "Does it make sense? Ask " + others + " readers")
           + '</button>');
-      if ((PKG.shots || []).length >= 6 && String(PKG.cuts_state || "") !== "thinking")
+      if ((PKG.shots || []).length >= 6 && !busyCuts())
         out.push('<button type="button" class="btn" data-cuts="' + esc(meta.id)
           + '" title="Several shorter versions of what is already filmed. '
           + 'Costs nothing to propose or to watch.">'
@@ -367,6 +367,14 @@
     return out.join("");
   }
 
+  // A cut may move shots as well as drop them, which makes it a different
+  // film rather than a shorter one. Worth saying out loud.
+  function reordered(ids) {
+    var a = (ids || []).map(String);
+    var b = a.slice().sort();
+    return a.join("") !== b.join("");
+  }
+
   function mmss(n) {
     return Math.floor(n / 60) + ":" + String(Math.round(n % 60)).padStart(2, "0");
   }
@@ -392,6 +400,16 @@
       + (worst && over > 5 ? "<ul>" + worst + "</ul>" : "") + "</div>";
   }
 
+  // A job lives in the worker's memory and dies with it. Every deploy kills
+  // one, and the flag it set stays set, so anything older than this is treated
+  // as gone rather than leaving the page waiting on it for ever.
+  function busyCuts() {
+    if (String(PKG.cuts_state || "") !== "thinking") return false;
+    var t = Date.parse(PKG.cuts_started || "");
+    if (!t) return false;
+    return (Date.now() - t) < 15 * 60 * 1000;
+  }
+
   // A cut is an ordering, not a render. Playing one is free, so all of them
   // can be looked at before anything is joined into a file.
   function cutsHtml(meta) {
@@ -406,7 +424,9 @@
       + 'the question is not “what is the right length” but “which '
       + 'version do people watch to the end”.</p>';
 
-    if (st === "thinking") out += '<p class="busy">Working out what to drop…</p>';
+    if (busyCuts()) out += '<p class="busy">Working out what to drop…</p>';
+    else if (st === "thinking") out += '<p class="cont">The last attempt stopped '
+      + 'before it finished — the server restarted under it. Ask again.</p>';
     else if (/^failed/.test(st)) out += '<p class="cont">' + esc(st) + '</p>';
 
     out += cuts.map(function (c) {
@@ -435,7 +455,8 @@
         + (stat ? '<p class="stat">' + stat.views + ' viewer'
             + (stat.views === 1 ? '' : 's') + ' · median ' + stat.median_percent
             + '% watched · ' + stat.completion_rate + '% reached the end</p>' : '')
-        + '<p class="ids">' + esc((c.shot_ids || []).join(" ")) + '</p>'
+        + '<p class="ids">' + esc((c.shot_ids || []).join(" "))
+        + (reordered(c.shot_ids) ? ' &middot; reordered' : '') + '</p>'
         + '<div class="tools">' + tools + '</div>' + play + '</div>';
     }).join("");