Harden viewer flow around paid synopses and series picker

- LLM Settings Save now closes the modal and, if the user has no saved
  results, routes to welcome so the Analyze form is visible instead of
  leaving them on the BB demo grid with no obvious next step.
- Series picker: selecting "+ Analyze another…" resets the select value
  to the current series so clicking it again re-fires change (otherwise
  it was a no-op when it had been the prior selection).
- Analyze: if a paid synopses draft is pending for a different show,
  confirm before overwriting rather than silently discarding work the
  user has already paid the LLM for.
- Analyze failure path: return to welcome and re-render the resume
  banner instead of stranding the user on an empty grid.
- Review cancel: ask before discarding the draft (safe-by-default —
  accidental Enter preserves synopses rather than throwing them away).

Author: BirdInTheTree

src/tvplot/html/parts/app.js

@@ -783,7 +783,14 @@ function _initApp() {
   if (btnTabAnalytics) btnTabAnalytics.addEventListener('click', () => _setTab('analytics'));
 
   if (seriesSelect) {
-    seriesSelect.addEventListener('change', () => _switchSeries(seriesSelect.value));
+    // "+ Analyze another…" is a one-shot action, not a selection — when the
+    // user picks it we reset the value so the next pick always fires `change`
+    // (fixes the case where it was the only option and clicking it was a no-op).
+    seriesSelect.addEventListener('change', () => {
+      const v = seriesSelect.value;
+      if (v === '__add__') seriesSelect.value = _currentSeriesName || '';
+      _switchSeries(v);
+    });
   }
 
   // Export dropdown — all .btn-export-trigger buttons open the shared menu

src/tvplot/html/parts/pipeline.js

@@ -726,6 +726,18 @@ async function _analyzeSeries(show, season) {
     return;
   }
 
+  // Protect existing draft — starting a new analysis would silently overwrite
+  // synopses the user already paid for. Ask first.
+  const existingDraft = Store.getSynopsesDraft();
+  if (existingDraft && existingDraft.show && existingDraft.synopses && existingDraft.synopses.length > 0) {
+    const draftLabel = `${existingDraft.show} S${String(existingDraft.season).padStart(2, '0')}`;
+    const replace = window.confirm(
+      `You have unfinished synopses for ${draftLabel} (generated previously at API cost).\n\n` +
+      `Starting a new analysis for ${show} S${String(season).padStart(2, '0')} will replace them. Continue?`,
+    );
+    if (!replace) return;
+  }
+
   // Move from welcome screen into the viewer shell so the progress overlay
   // fits the normal layout. The grid may be empty (no data yet) — that's
   // fine, the progress overlay covers it until the pipeline finishes.
@@ -744,6 +756,11 @@ async function _analyzeSeries(show, season) {
     if (synopses.length === 0) throw new Error('All returned synopses were empty.');
   } catch (err) {
     _hidePipelineProgress();
+    // Return to welcome so the user isn't stranded on an empty grid with a
+    // dropdown whose only option is "+ Analyze another…" (which, being the
+    // current value, no longer fires a `change` event on re-selection).
+    showScreen('welcome');
+    _renderResumeBanner && _renderResumeBanner();
     alert(`Couldn't fetch synopses: ${err.message}`);
     return;
   }
@@ -769,7 +786,13 @@ async function _analyzeSeries(show, season) {
 async function _reviewAndRun(show, season, synopses, provider, apiKey) {
   const confirmed = await _confirmSynopses(show, season, synopses);
   if (!confirmed) {
-    Store.clearSynopsesDraft();
+    // Synopses were generated at API cost — ask to keep by default (OK = save,
+    // Cancel = discard). Safe-by-default: accidental Enter preserves the draft.
+    const save = window.confirm(
+      `Save the generated synopses for ${show} S${String(season).padStart(2, '0')}?\n\n` +
+      `They were produced by a paid LLM call. Saving lets you resume later without regenerating.`,
+    );
+    if (!save) Store.clearSynopsesDraft();
     return;
   }