polish(reconcile): throttle back-to-back sweeps, document the sync call site

main.js

@@ -1,5 +1,5 @@
 const { app, BrowserWindow, clipboard, dialog, ipcMain, Menu, screen, shell } = require('electron');
 const { Worker } = require('worker_threads');
 const { execFile } = require('child_process');
 const path = require('path');
 const fs = require('fs');
@@ -16,7 +16,7 @@
 }
 
 // getFolderIndexMtimeMs moved to session-cache.js
 const { startMcpServer, shutdownMcpServer, shutdownAll: shutdownAllMcp, resolvePendingDiff, rekeyMcpServer, cleanStaleLockFiles } = require('./mcp-bridge');
 const { fetchAndTransformUsage } = require('./claude-auth');
 log.transports.file.level = app.isPackaged ? 'info' : 'debug';
 log.transports.console.level = app.isPackaged ? 'info' : 'debug';
@@ -36,7 +36,7 @@
 );
 
 // Shell profiles → shell-profiles.js
 const { discoverShellProfiles, getShellProfiles, resolveShell, isWindows, isWslShell, windowsToWslPath, shellArgs } = require('./shell-profiles');
 const { startScheduler } = require('./schedule-runner');
 const { encodeProjectPath } = require('./encode-project-path');
 
@@ -73,7 +73,7 @@
   getMeta, getAllMeta, toggleStar, setName, setArchived,
   isCachePopulated, getAllCached, getCachedByFolder, getCachedByParent, getCachedFolder, getCachedSession, upsertCachedSessions,
   deleteCachedSession, deleteCachedFolder, replaceSessionMetrics, touchCachedModified,
   getFolderMeta, getAllFolderMeta, setFolderMeta,
   upsertSearchEntries, updateSearchTitle, deleteSearchSession, deleteSearchFolder, deleteSearchType,
   searchByType, isSearchIndexPopulated, searchFtsRecreated,
   getSetting, setSetting, deleteSetting,
@@ -290,8 +290,8 @@
     setFolderMeta, getAllFolderMeta, getAllMeta, getAllCached, getSetting, getMeta, setName,
   },
 });
 const { readSessionFile, readFolderFromFilesystem, refreshFolder, reconcileCacheFromFilesystem,
         buildProjectsFromCache, notifyRendererProjectsChanged, sendStatus, populateCacheViaWorker } = sessionCache;
 const { resolveJsonlPath, enumerateSessionFiles } = require('./read-session-file');
 
 
@@ -648,6 +648,8 @@
       // Cache already populated: pick up folders changed while the app was
       // closed, or never indexed by an older build, so sessions/worktrees don't
       // silently go missing. Stat-gated, so it's cheap when nothing has changed.
+      // Synchronous (readdir/stat sweep) — completes before buildProjectsFromCache
+      // below; no await needed despite the await in the cold-start branch above.
       reconcileCacheFromFilesystem();
     }
 
@@ -1408,7 +1410,7 @@
   // WSL profiles only work for plain terminals — Claude CLI sessions need the
   // Windows shell because session data lives on the Windows filesystem.
   const requestedProfile = resolveShell(effectiveProfileId);
   const useWslProfile = isWslShell(requestedProfile.path) && isPlainTerminal;
   const shellProfile = (isWslShell(requestedProfile.path) && !isPlainTerminal)
     ? resolveShell('auto')
     : requestedProfile;

session-cache.js

@@ -270,8 +270,19 @@ function refreshFolder(folder, opts = {}) {
  * app was closed, or that predates the build which first indexed it, is
  * otherwise never picked up, because the cold-start full scan
  * (populateCacheViaWorker) only runs when the cache is completely empty.
+ *
+ * Throttled: the renderer's loadProjects() fires get-projects twice per sidebar
+ * paint (showArchived false/true via Promise.all), which would run the sweep
+ * back-to-back. The second pass is idempotent but wasted work — and skipping it
+ * keeps a single metaMap snapshot per paint. Changes landing inside the
+ * throttle window are still picked up by the live watcher.
  */
+const RECONCILE_THROTTLE_MS = 1000;
+let lastReconcileAt = 0;
 function reconcileCacheFromFilesystem() {
+  const now = Date.now();
+  if (now - lastReconcileAt < RECONCILE_THROTTLE_MS) return;
+  lastReconcileAt = now;
   try {
     const metaMap = getAllFolderMeta();
     const folders = fs.readdirSync(PROJECTS_DIR, { withFileTypes: true })