feat(assessmentsAverage): fingerprint-based reindex with non-blocking refresh

- Add WEIGHTING_SCHEMA_VERSION constant; bump to force a global lazy reindex
 - Migrate legacy Record<id, string> storage to { weight, fingerprint, pluginVersion }
 - Fingerprint per-assessment on status, graded, availability, score, due, title (sourced from the React fiber)
 - Refetch weighting only when fingerprint or schema version mismatches
 - Preserve previous weight as refreshing placeholder during background refetch
 - Render subject average immediately from cache; run parseAssessments off the critical path
 - Coalesce concurrent renderSubjectAverage calls instead of dropping them
 - Dispatch betterseqta:weightingsChanged on refetch start and completion
 - Show row-level refresh indicator and "Refreshing weightings" notice while refreshing
 - Leave weightingOverrides untouched by all reindex paths

src/plugins/built-in/assessmentsAverage/index.ts

@@ -15,11 +15,12 @@ import {
   letterToNumber,
   parseAssessments,
   processAssessments,
+  type WeightingEntry,
 } from "./utils.ts";
 import { injectRubricCopyButtons } from "./rubricCopy.ts";
 
 interface weightingsStorage {
-  weightings: Record<string, string>;
+  weightings: Record<string, WeightingEntry>;
   assessments: Record<string, string>;
   weightingOverrides: Record<string, string>;
 }
@@ -61,8 +62,8 @@ const assessmentsAveragePlugin: Plugin<typeof settings, weightingsStorage> = {
         1000,
       );
 
-      await parseAssessments(api);
-      await renderSubjectAverage(api);
+      // Wire listeners first so the very first re-render triggered by a
+      // background handleWeightings completion can find them.
       overrideListenerController?.abort();
       overrideListenerController = new AbortController();
       document.addEventListener(
@@ -70,6 +71,21 @@ const assessmentsAveragePlugin: Plugin<typeof settings, weightingsStorage> = {
         () => renderSubjectAverage(api),
         { signal: overrideListenerController.signal },
       );
+      document.addEventListener(
+        "betterseqta:weightingsChanged",
+        () => renderSubjectAverage(api),
+        { signal: overrideListenerController.signal },
+      );
+
+      // Render immediately with whatever is already cached. Fresh entries
+      // and stale-with-previous-value entries both contribute their numeric
+      // weights, so the subject average appears without waiting on any
+      // background PDF refetches.
+      await renderSubjectAverage(api);
+
+      // Kick off indexing in the background. Each completion dispatches
+      // betterseqta:weightingsChanged, which triggers a fresh render.
+      void parseAssessments(api);
       const wrapper = document.querySelector(".assessmentsWrapper");
       if (wrapper) {
         const observer = new MutationObserver(() => {
@@ -87,8 +103,15 @@ const assessmentsAveragePlugin: Plugin<typeof settings, weightingsStorage> = {
 };
 
 let renderInFlight = false;
+let renderQueued = false;
 async function renderSubjectAverage(api: any) {
-  if (renderInFlight) return;
+  if (renderInFlight) {
+    // Coalesce: remember that fresh data arrived during this render and
+    // re-run once the current pass finishes, so the UI catches up to the
+    // latest storage state instead of silently dropping the event.
+    renderQueued = true;
+    return;
+  }
   renderInFlight = true;
 
   try {
@@ -141,8 +164,13 @@ async function renderSubjectAverage(api: any) {
           ?.textContent?.includes("Subject Average"),
     );
 
-    const { weightedTotal, totalWeight, hasInaccurateWeighting, count } =
-      await processAssessments(api, assessmentItems);
+    const {
+      weightedTotal,
+      totalWeight,
+      hasInaccurateWeighting,
+      hasRefreshingWeighting,
+      count,
+    } = await processAssessments(api, assessmentItems);
     if (!count || totalWeight === 0) return;
 
     const thermoscoreElement = document.querySelector(
@@ -176,11 +204,22 @@ async function renderSubjectAverage(api: any) {
     let warningHTML = "";
     if (hasInaccurateWeighting) {
       warningHTML = /* html */ `
-            <div style="margin-top: 4px; font-size: 11px; color: rgba(255, 255, 255, 0.6); opacity: 0.8; line-height: 1.3;">
+            <div style="margin-top: 4px; font-size: 11px; color: rgba(255, 255, 255, 0.6); opacity: 0.8; line-height: 1.3; white-space: nowrap;">
               ⚠ Some weightings unavailable
             </div>
           `;
+    } else if (hasRefreshingWeighting) {
+      warningHTML = /* html */ `
+            <div style="margin-top: 4px; font-size: 11px; color: rgba(255, 255, 255, 0.55); opacity: 0.8; line-height: 1.3; white-space: nowrap;" title="Some weightings are being re-checked; the average may change shortly">
+              ↻ Refreshing weightings
+            </div>
+          `;
     }
+    const thermoscoreTitle = hasInaccurateWeighting
+      ? `${display} (some weightings unavailable)`
+      : hasRefreshingWeighting
+        ? `${display} (re-checking weightings)`
+        : display;
     assessmentsList.insertBefore(
       stringToHTML(/* html */ `
           <div class="${assessmentItemClass}">
@@ -194,7 +233,7 @@ async function renderSubjectAverage(api: any) {
             </div>
             <div class="${thermoscoreClass}">
               <div class="${fillClass}" style="width: ${avg.toFixed(2)}%">
-                <div class="${textClass}" title="${hasInaccurateWeighting ? display + " (some weightings unavailable)" : display}">${display}</div>
+                <div class="${textClass}" title="${thermoscoreTitle}">${display}</div>
               </div>
             </div>
           </div>
@@ -204,6 +243,10 @@ async function renderSubjectAverage(api: any) {
     applySubjectColourToOverallResult();
   } finally {
     renderInFlight = false;
+    if (renderQueued) {
+      renderQueued = false;
+      void renderSubjectAverage(api);
+    }
   }
 }
 function applySubjectColourToOverallResult() {