fix(period): [ and ] snap odd ranges to calendar months, fresh visit opens the current period

src/lib/period.svelte.ts

@@ -5,7 +5,7 @@ import {
   isDynamic,
   periodOf,
   type Range,
-  shiftPeriod,
+  stepPeriod,
   today,
   type ViewRange,
 } from "#lib/dates.js";
@@ -23,7 +23,7 @@ export interface Preset {
 
 function stored(): Range | null {
   try {
-    const value = JSON.parse(localStorage.getItem(STORAGE_KEY) ?? "null");
+    const value = JSON.parse(sessionStorage.getItem(STORAGE_KEY) ?? "null");
     return ISO_DATE.test(value?.start) && ISO_DATE.test(value?.end)
       ? value
       : null;
@@ -71,7 +71,7 @@ class Period {
     const range = rangeFromUrl(url) ?? stored() ?? periodOf(today(), view);
     this.start = range.start;
     this.end = range.end;
-    localStorage.setItem(STORAGE_KEY, JSON.stringify(range));
+    sessionStorage.setItem(STORAGE_KEY, JSON.stringify(range));
     this.ready = true;
   }
 
@@ -97,11 +97,11 @@ class Period {
     }
     this.start = range.start;
     this.end = range.end;
-    localStorage.setItem(STORAGE_KEY, JSON.stringify(range));
+    sessionStorage.setItem(STORAGE_KEY, JSON.stringify(range));
   }
 
   shift(dir: 1 | -1) {
-    this.set(shiftPeriod(this.range, this.view, dir));
+    this.set(stepPeriod(this.range, this.view, dir));
   }
 
   reset() {
@@ -113,8 +113,8 @@ class Period {
     const { view } = this;
     const presets: Preset[] = [];
     if (!isDynamic(view)) {
-      const prev = shiftPeriod(this.range, view, -1);
-      const next = shiftPeriod(this.range, view, 1);
+      const prev = stepPeriod(this.range, view, -1);
+      const next = stepPeriod(this.range, view, 1);
       presets.push({ hint: "[", label: periodLabel(prev, view), range: prev });
       presets.push({ hint: "]", label: periodLabel(next, view), range: next });
     }