diff --git a/src/app/features/calendar-integration/store/calendar-integration.effects.ts b/src/app/features/calendar-integration/store/calendar-integration.effects.ts
index ac269d201f..7fd23dfe23 100644
--- a/src/app/features/calendar-integration/store/calendar-integration.effects.ts
+++ b/src/app/features/calendar-integration/store/calendar-integration.effects.ts
@@ -55,12 +55,16 @@ export class CalendarIntegrationEffects {
    * Poll external calendar providers for events and auto-import them as tasks.
    *
    * The auto-import branch is gated on `isInitialSyncDoneSync() &&
-   * !isInSyncWindow()`. The `!isInSyncWindow()` half is what
-   * `skipDuringSyncWindow()` would give us; the `isInitialSyncDoneSync()`
-   * half is stricter — it also blocks before the very first sync completes,
-   * which the operator alone does not cover. The combined gate can't be
-   * lifted to the outer pipe because the banner-display branch must keep
-   * firing during sync.
+   * !isInSyncWindow()` — the same predicate as `skipDuringSyncWindow()`
+   * (see `src/app/util/skip-during-sync-window.operator.ts`). We hand-roll
+   * it here rather than using the operator because:
+   *   1. The operator filters emissions on a stream; this effect runs its
+   *      side effects inside `tap(async () => …)`, not on an emission.
+   *   2. The banner-display branch (further down in the same tap) must
+   *      keep firing during sync, so the gate cannot be lifted to the
+   *      outer pipe.
+   * Refactoring the tap into `exhaustMap(...) → skipDuringSyncWindow() →
+   * tap(import)` would let the operator be reused; left as a follow-up.
    *
    * Why the gate matters: calendar task IDs are deterministic across devices
    * (see `generateCalendarTaskId`), so a pre-first-sync import on a second
diff --git a/src/app/features/config/form-cfgs/sync-form.const.ts b/src/app/features/config/form-cfgs/sync-form.const.ts
index d11179ad8d..8bc6f3cdc5 100644
--- a/src/app/features/config/form-cfgs/sync-form.const.ts
+++ b/src/app/features/config/form-cfgs/sync-form.const.ts
@@ -551,10 +551,17 @@ export const SYNC_FORM: ConfigFormSection<SyncConfig> = {
             onClick: async (field: FormlyFieldConfig) => {
               const result = await openEnableEncryptionDialog();
               if (result?.success) {
-                // Sub-model write keeps the SuperSync nested form section in
-                // sync; the root write is what the sibling hideExpressions
-                // (info-panel, ENCRYPTION_ENCOURAGED, this button) read,
-                // mirroring the Disable flow above.
+                // Two writes are needed (asymmetric with the Disable flow,
+                // which only needs the root write):
+                //   - Sub-model: `sync-config.service._deriveEncryptionState
+                //     ForSuperSync` reads `superSync.isEncryptionEnabled`
+                //     first in its fallback chain (privateCfg comes second).
+                //     Writing it here ensures the next form-save derives
+                //     `true` even if `privateCfg` propagation lags.
+                //   - Root: sibling hideExpressions (info-panel,
+                //     ENCRYPTION_ENCOURAGED, this button) read the root
+                //     flag, so it must flip in the current Formly tick to
+                //     hide them immediately.
                 if (field?.model) {
                   field.model.isEncryptionEnabled = true;
                 }