fix(config-backup): a restore after a reset keeps the retention, the mode probe cannot write through a planted symlink, the form shows the retention in use

src/web/public/settings-ui.js

@@ -1388,6 +1388,13 @@ Object.assign(CodemanApp.prototype, {
     const data = body.data;
     const dirInput = this.$('appSettingsConfigBackupDir') || document.getElementById('appSettingsConfigBackupDir');
     if (dirInput && data.defaultDir) dirInput.placeholder = `default: ${data.defaultDir}`;
+    // A reset settings.json has none of the four keys, but the passes keep the retention the newest backup
+    // recorded: show that, or a Save would write 20 / 30 over it.
+    const saved = this.loadAppSettingsFromStorage();
+    const countInput = document.getElementById('appSettingsConfigBackupKeepCount');
+    const daysInput = document.getElementById('appSettingsConfigBackupKeepDays');
+    if (countInput && saved.configBackupKeepCount === undefined && data.settings) countInput.value = data.settings.keepCount;
+    if (daysInput && saved.configBackupKeepDays === undefined && data.settings) daysInput.value = data.settings.keepDays;
     if (!data.backups.length) {
       out.innerHTML = `No backups yet in <code>${escapeHtml(data.dir)}</code>.`;
       return;

src/web/routes/config-backup-routes.ts

@@ -40,8 +40,7 @@ import {
   resolveConfigBackupDir,
   restoreConfigBackup,
   configBackupOrigin,
-  hasConfigBackupSettings,
-  latestBackupRetention,
+  withRecordedRetention,
   readConfigBackupOrigin,
   sweepConfigBackupTemps,
   type ConfigBackupResult,
@@ -73,8 +72,10 @@ export interface ConfigBackupStatus {
 
 export async function readEffectiveBackupSettings(): Promise<{ settings: ConfigBackupSettings; dir: string }> {
   const raw = await readJsonConfig<Record<string, unknown>>(SETTINGS_PATH, 'settings.json', {});
-  const settings = readConfigBackupSettings(raw);
-  return { settings, dir: resolveConfigBackupDir(settings, getDataDir()) };
+  const base = readConfigBackupSettings(raw);
+  const dir = resolveConfigBackupDir(base, getDataDir());
+  // The same fallback the timer pass uses, so the form never shows 20 / 30 while a pass keeps 100 / 0.
+  return { settings: withRecordedRetention(base, raw, dir, readConfigBackupOrigin(getDataDir())), dir };
 }
 
 /** A user-chosen backup folder that is not safe to touch (bounded probe, as for case paths, #516). */
@@ -128,10 +129,7 @@ export async function runConfigBackup(
   sweepConfigBackupTemps(dir);
   const origin = configBackupOrigin(getDataDir());
   // No backup settings in the file (reset, or unreadable): keep the retention the newest snapshot recorded.
-  const settings =
-    unreadable || !hasConfigBackupSettings(raw)
-      ? { ...fromFile, ...(latestBackupRetention(dir, origin) ?? {}) }
-      : fromFile;
+  const settings = withRecordedRetention(fromFile, unreadable ? {} : raw, dir, origin);
   const result = createConfigBackup({
     dataDir: getDataDir(),
     backupDir: dir,