Add timeline engine size routing

assets/js/tools.js

@@ -755,6 +755,21 @@ function currentTimelineEngine() {
   return document.querySelector('input[name="timelineEngine"]:checked')?.value || 'azure_mini';
 }
 
+function timelineEngineLabel(engine) {
+  return {
+    nova_lite: 'Quick',
+    azure_mini: 'Standard',
+    azure_full: 'Deep',
+  }[engine] || 'Timeline';
+}
+
+function timelineClientRoute(engine, charCount) {
+  let effective = engine;
+  if (charCount > 55000) effective = 'azure_full';
+  else if (charCount > 25000 && effective === 'nova_lite') effective = 'azure_mini';
+  return { effective, upgraded: effective !== engine };
+}
+
 function currentTimelineFocus() {
   return document.querySelector('input[name="timelineFocus"]:checked')?.value || 'all';
 }
@@ -1104,14 +1119,19 @@ async function runTool(event) {
     payload.redact_types   = currentRedactTypes();
     lastRedactPayload = { ...payload };
   }
+  let timelineRouteNotice = '';
   if (state.activeTool === 'timeline') {
     payload.engine             = currentTimelineEngine();
+    const clientRoute          = timelineClientRoute(payload.engine, text.length);
     payload.focus              = currentTimelineFocus();
     payload.confidence_filter  = currentConfidenceFilter();
     payload.include_relative   = currentIncludeRelative();
     payload.include_background = currentIncludeBackground();
     payload.user_notes         = (document.getElementById('timelineNotes')?.value || '').trim();
     payload.use_my_case        = (typeof window.dbnGetUseMyCase === 'function') ? window.dbnGetUseMyCase() : false;
+    timelineRouteNotice = clientRoute.upgraded
+      ? `This input is ${text.length.toLocaleString()} characters, so Timeline will use ${timelineEngineLabel(clientRoute.effective)} for reliability.`
+      : '';
   }
 
   lastToolPayload = { ...payload };
@@ -1121,7 +1141,8 @@ async function runTool(event) {
     els.results.innerHTML = '<div class="redact-working" role="status" aria-live="polite"><span class="redact-working__spinner" aria-hidden="true"></span><p>Redacting document…</p></div>';
   }
   if (state.activeTool === 'timeline') {
-    els.results.innerHTML = '<div class="redact-working" id="timelineWorkingState" role="status" aria-live="polite"><span class="redact-working__spinner" aria-hidden="true"></span><p id="timelineStatusMsg">Building timeline…</p></div>';
+    const routeNotice = timelineRouteNotice ? `<p class="upload-hint">${escapeHtml(timelineRouteNotice)}</p>` : '';
+    els.results.innerHTML = `<div class="redact-working" id="timelineWorkingState" role="status" aria-live="polite"><span class="redact-working__spinner" aria-hidden="true"></span><p id="timelineStatusMsg">Building timeline…</p>${routeNotice}</div>`;
   }
   renderTrace([
     { label: 'Query interpretation', detail: 'Preparing request.', status: 'running' },
@@ -1172,7 +1193,11 @@ async function runTool(event) {
     }
     renderResults(data);
     renderTrace(data.trace || []);
-    els.status.textContent = `Done in ${data.latency_ms || 0} ms.`;
+    const routeMeta = data.trace_metadata || {};
+    const serverRouteNotice = state.activeTool === 'timeline' && routeMeta.auto_upgraded_engine
+      ? ` Used ${timelineEngineLabel(routeMeta.effective_engine)} for ${Number(routeMeta.input_char_count || 0).toLocaleString()} characters.`
+      : '';
+    els.status.textContent = `Done in ${data.latency_ms || 0} ms.${serverRouteNotice}`;
     if (['ask', 'redact', 'timeline'].includes(state.activeTool)) {
       showSaveResultButton(state.activeTool, lastToolPayload, data, {
         model: data.trace_metadata?.deployment || null,