fixed share link bug

index.html

@@ -1333,10 +1333,13 @@
                 onclick: () => exportSolve({token, n, solution: s, problem, maxTime,
                     name: solveLabel(token, n)}),
             }, "Export"));
-            if (problem) {
+            // The problem may be on hand (a solve queued from this tab) or, for a
+            // solve opened via a share link, fetched from the server by token on
+            // click — the same lazy lookup exportSolve uses.
+            if (problem || token) {
                 actions.append(" ", el("button", {
                     class: "mini", type: "button",
-                    onclick: () => applyProblem(problem, maxTime),
+                    onclick: () => loadParamsIntoForm(problem, maxTime, token),
                 }, "Load parameters into form"));
             }
             out.append(actions);
@@ -1647,8 +1650,27 @@
             reader.readAsText(file);
         }
 
+        // Backs the "Load parameters into form" button. Uses the problem we
+        // already hold for a locally-queued solve, otherwise fetches it from the
+        // server by token (a share-link viewer never had it locally).
+        async function loadParamsIntoForm(problem, maxTime, token) {
+            let prob = problem, mt = maxTime;
+            if (!prob && token) {
+                try {
+                    const r = await fetch("/solve/" + encodeURIComponent(token));
+                    if (r.ok) prob = (await r.json()).problem;
+                } catch (e) {/* fall through: nothing to load */}
+            }
+            if (!prob) {
+                document.getElementById("error").textContent =
+                    "Could not load this solve's parameters (it may have been evicted).";
+                return;
+            }
+            applyProblem(prob, mt);
+        }
+
         // Load a problem's input parameters back into the form, replacing the
-        // current inputs. Backs the "Load parameters into form" button.
+        // current inputs.
         function applyProblem(problem, maxTime) {
             if (!problem) return;
             const setVal = (id, v) => {