From 130ccc0f731a3ca05895a4782a9581ceabe3e859 Mon Sep 17 00:00:00 2001
From: Leo Vasanko <leo@git>
Date: Sun, 24 Aug 2025 21:59:56 -0600
Subject: [PATCH] Simple undo/redo

---
 package.json                         |   2 +-
 src/App.vue                          |  31 ++++-
 src/assets/layout.css                |  83 ++++++++---
 src/components/CalendarView.vue      |  57 +++++++-
 src/components/EventDialog.vue       |  13 ++
 src/components/EventOverlay.vue      |  36 ++++-
 src/main.js                          |   3 +
 src/plugins/calendarHistory.js       | 200 +++++++++++++++++++++++++++
 src/plugins/calendarUndoNormalize.js |  57 ++++++++
 src/stores/CalendarStore.js          |   4 +
 10 files changed, 459 insertions(+), 27 deletions(-)
 create mode 100644 src/plugins/calendarHistory.js
 create mode 100644 src/plugins/calendarUndoNormalize.js

diff --git a/package.json b/package.json
index 7e0f7b7..cca40c0 100644
--- a/package.json
+++ b/package.json
@@ -16,9 +16,9 @@
     "format": "prettier --write src/"
   },
   "dependencies": {
-    "date-holidays": "^3.25.1",
     "date-fns": "^3.6.0",
     "date-fns-tz": "^3.0.0",
+    "date-holidays": "^3.25.1",
     "pinia": "^3.0.3",
     "pinia-plugin-persistedstate": "^4.5.0",
     "vue": "^3.5.18"
diff --git a/src/App.vue b/src/App.vue
index 451c0d9..5836a2c 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -1,5 +1,5 @@
 <script setup>
-import { ref, onMounted } from 'vue'
+import { ref, onMounted, onBeforeUnmount } from 'vue'
 import CalendarView from './components/CalendarView.vue'
 import EventDialog from './components/EventDialog.vue'
 import { useCalendarStore } from './stores/CalendarStore'
@@ -8,8 +8,37 @@ const eventDialog = ref(null)
 const calendarStore = useCalendarStore()
 
 // Initialize holidays when app starts
+function isEditableElement(el) {
+  if (!el) return false
+  const tag = el.tagName
+  if (tag === 'INPUT' || tag === 'TEXTAREA') return true
+  if (el.isContentEditable) return true
+  return false
+}
+
+function handleGlobalKey(e) {
+  // Only consider Ctrl/Meta+Z combos
+  if (!(e.ctrlKey || e.metaKey)) return
+  if (e.key !== 'z' && e.key !== 'Z') return
+  // Don't interfere with native undo/redo inside editable fields
+  const target = e.target
+  if (isEditableElement(target)) return
+  // Decide undo vs redo (Shift = redo)
+  if (e.shiftKey) {
+    calendarStore.$history?.redo()
+  } else {
+    calendarStore.$history?.undo()
+  }
+  e.preventDefault()
+}
+
 onMounted(() => {
   calendarStore.initializeHolidaysFromConfig()
+  document.addEventListener('keydown', handleGlobalKey, { passive: false })
+})
+
+onBeforeUnmount(() => {
+  document.removeEventListener('keydown', handleGlobalKey)
 })
 
 const handleCreateEvent = (eventData) => {
diff --git a/src/assets/layout.css b/src/assets/layout.css
index f9e0cf9..2c3be74 100644
--- a/src/assets/layout.css
+++ b/src/assets/layout.css
@@ -9,13 +9,25 @@
 }
 
 /* Layout & typography */
-* { box-sizing: border-box }
+* {
+  box-sizing: border-box;
+}
 
-html, body { height: 100%; }
+html,
+body {
+  height: 100%;
+}
 
 body {
   margin: 0;
-  font: 500 14px/1.2 ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Inter, Arial;
+  font:
+    500 14px/1.2 ui-sans-serif,
+    system-ui,
+    -apple-system,
+    Segoe UI,
+    Roboto,
+    Inter,
+    Arial;
   background: var(--bg);
   color: var(--ink);
   /* Prevent body scrolling / unwanted scrollbars due to mobile browser UI chrome affecting vh */
@@ -23,38 +35,50 @@ body {
 }
 
 /* Ensure root app container doesn't introduce its own scrollbars */
-#app { height: 100%; width: 100%; overflow: hidden; }
+#app {
+  height: 100%;
+  width: 100%;
+  overflow: hidden;
+}
 
 header {
   display: flex;
   align-items: baseline;
   justify-content: space-between;
-  margin-bottom: .75rem;
+  margin-bottom: 0.75rem;
   flex-shrink: 0;
 }
 
 .header-controls {
   display: flex;
   align-items: center;
-  gap: .75rem;
+  gap: 0.75rem;
 }
 
-.today-date { cursor: pointer }
-.today-date::first-line { color: var(--today) }
-.today-button:hover { opacity: .8 }
+.today-date {
+  cursor: pointer;
+}
+.today-date::first-line {
+  color: var(--today);
+}
+.today-button:hover {
+  opacity: 0.8;
+}
 
 /* Header row */
-.calendar-header, #calendar-header {
+.calendar-header,
+#calendar-header {
   display: grid;
   grid-template-columns: var(--label-w) repeat(7, var(--cell-w)) var(--overlay-w);
-  border-bottom: .2em solid var(--muted);
+  border-bottom: 0.2em solid var(--muted);
   align-items: last baseline;
   flex-shrink: 0;
   width: 100%;
 }
 
 /* Main container */
-.calendar-container, #calendar-container {
+.calendar-container,
+#calendar-container {
   flex: 1;
   overflow: hidden;
   position: relative;
@@ -63,7 +87,8 @@ header {
 }
 
 /* Viewports (support id or class) */
-.calendar-viewport, #calendar-viewport {
+.calendar-viewport,
+#calendar-viewport {
   height: 100%;
   overflow-y: auto;
   overflow-x: hidden;
@@ -72,11 +97,16 @@ header {
   scrollbar-width: none;
 }
 .calendar-viewport::-webkit-scrollbar,
-#calendar-viewport::-webkit-scrollbar { display: none }
+#calendar-viewport::-webkit-scrollbar {
+  display: none;
+}
 
-.jogwheel-viewport, #jogwheel-viewport {
+.jogwheel-viewport,
+#jogwheel-viewport {
   position: absolute;
-  top: 0; right: 0; bottom: 0;
+  top: 0;
+  right: 0;
+  bottom: 0;
   width: var(--overlay-w);
   overflow-y: auto;
   overflow-x: hidden;
@@ -85,10 +115,19 @@ header {
   cursor: ns-resize;
 }
 .jogwheel-viewport::-webkit-scrollbar,
-#jogwheel-viewport::-webkit-scrollbar { display: none }
+#jogwheel-viewport::-webkit-scrollbar {
+  display: none;
+}
 
-.jogwheel-content, #jogwheel-content { position: relative; width: 100% }
-.calendar-content, #calendar-content { position: relative }
+.jogwheel-content,
+#jogwheel-content {
+  position: relative;
+  width: 100%;
+}
+.calendar-content,
+#calendar-content {
+  position: relative;
+}
 
 /* Week row: label + 7-day grid + jogwheel column */
 .week-row {
@@ -102,7 +141,8 @@ header {
 }
 
 /* Label cells */
-.year-label, .week-label {
+.year-label,
+.week-label {
   display: grid;
   place-items: center;
   width: 100%;
@@ -137,7 +177,8 @@ header {
   z-index: 15;
   overflow: visible;
   position: absolute;
-  top: 0; right: 0;
+  top: 0;
+  right: 0;
   width: 100%;
 }
 .month-name-label > span {
diff --git a/src/components/CalendarView.vue b/src/components/CalendarView.vue
index f2b43d2..411a7b7 100644
--- a/src/components/CalendarView.vue
+++ b/src/components/CalendarView.vue
@@ -588,6 +588,27 @@ window.addEventListener('resize', () => {
       <h1>Calendar</h1>
       <div class="header-controls">
         <div class="today-date" @click="goToToday">{{ todayString }}</div>
+        <!-- Reference historyTick to ensure reactivity of canUndo/canRedo -->
+        <button
+          type="button"
+          class="hist-btn"
+          :disabled="!calendarStore.historyCanUndo"
+          @click="calendarStore.$history?.undo()"
+          title="Undo (Ctrl+Z)"
+          aria-label="Undo"
+        >
+          ↶
+        </button>
+        <button
+          type="button"
+          class="hist-btn"
+          :disabled="!calendarStore.historyCanRedo"
+          @click="calendarStore.$history?.redo()"
+          title="Redo (Ctrl+Shift+Z)"
+          aria-label="Redo"
+        >
+          ↷
+        </button>
         <button
           type="button"
           class="settings-btn"
@@ -657,18 +678,21 @@ window.addEventListener('resize', () => {
 
 header {
   display: flex;
-  justify-content: space-between;
   align-items: center;
+  gap: 1.25rem;
+  padding: 0.75rem 0.5rem 0.25rem 0.5rem;
 }
-
 header h1 {
   margin: 0;
   padding: 0;
+  font-size: 1.6rem;
+  font-weight: 600;
 }
 .header-controls {
   display: flex;
-  gap: 1rem;
+  gap: 0.6rem;
   align-items: center;
+  margin-left: auto;
 }
 
 .settings-btn {
@@ -686,6 +710,33 @@ header h1 {
   justify-content: center;
   outline: none;
 }
+.hist-btn {
+  background: transparent;
+  border: none;
+  color: var(--muted);
+  padding: 0;
+  margin: 0;
+  cursor: pointer;
+  font-size: 1.2rem;
+  line-height: 1;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  outline: none;
+  width: 1.9rem;
+  height: 1.9rem;
+}
+.hist-btn:disabled {
+  opacity: 0.35;
+  cursor: default;
+}
+.hist-btn:not(:disabled):hover,
+.hist-btn:not(:disabled):focus-visible {
+  color: var(--strong);
+}
+.hist-btn:active:not(:disabled) {
+  transform: scale(0.88);
+}
 .settings-btn:hover {
   color: var(--strong);
 }
diff --git a/src/components/EventDialog.vue b/src/components/EventDialog.vue
index cd4f60c..d0539e4 100644
--- a/src/components/EventDialog.vue
+++ b/src/components/EventDialog.vue
@@ -37,6 +37,7 @@ const title = computed({
   set(v) {
     if (editingEventId.value && calendarStore.events?.has(editingEventId.value)) {
       calendarStore.events.get(editingEventId.value).title = v
+      calendarStore.touchEvents()
     }
   },
 })
@@ -127,6 +128,7 @@ const selectedColor = computed({
     const n = parseInt(v)
     if (editingEventId.value && calendarStore.events?.has(editingEventId.value)) {
       calendarStore.events.get(editingEventId.value).colorId = n
+      calendarStore.touchEvents()
     }
     colorId.value = n
   },
@@ -144,6 +146,7 @@ const repeatCountBinding = computed({
   set(v) {
     if (editingEventId.value && calendarStore.events?.has(editingEventId.value)) {
       calendarStore.events.get(editingEventId.value).repeatCount = v === 0 ? 'unlimited' : String(v)
+      calendarStore.touchEvents()
     }
     recurrenceOccurrences.value = v
   },
@@ -189,6 +192,7 @@ function loadWeekdayPatternFromStore(storePattern) {
 }
 
 function openCreateDialog(selectionData = null) {
+  calendarStore.$history?.beginCompound()
   if (unsavedCreateId.value && !eventSaved.value) {
     if (calendarStore.events?.has(unsavedCreateId.value)) {
       calendarStore.deleteEvent(unsavedCreateId.value)
@@ -249,6 +253,7 @@ function openCreateDialog(selectionData = null) {
 }
 
 function openEditDialog(payload) {
+  calendarStore.$history?.beginCompound()
   if (
     dialogMode.value === 'create' &&
     unsavedCreateId.value &&
@@ -352,6 +357,7 @@ function openEditDialog(payload) {
 }
 
 function closeDialog() {
+  calendarStore.$history?.endCompound()
   showDialog.value = false
 }
 
@@ -367,6 +373,7 @@ function updateEventInStore() {
     event.repeatCount =
       recurrenceOccurrences.value === 0 ? 'unlimited' : String(recurrenceOccurrences.value)
     event.isRepeating = recurrenceEnabled.value && repeat.value !== 'none'
+    calendarStore.touchEvents()
   }
 }
 
@@ -377,11 +384,13 @@ function saveEvent() {
     unsavedCreateId.value = null
   }
   if (dialogMode.value === 'create') emit('clear-selection')
+  calendarStore.$history?.endCompound()
   closeDialog()
 }
 
 function deleteEventAll() {
   if (editingEventId.value) calendarStore.deleteEvent(editingEventId.value)
+  calendarStore.$history?.endCompound()
   closeDialog()
 }
 
@@ -391,12 +400,14 @@ function deleteEventOne() {
   } else if (isRepeatingBaseEdit.value && editingEventId.value) {
     calendarStore.deleteFirstOccurrence(editingEventId.value)
   }
+  calendarStore.$history?.endCompound()
   closeDialog()
 }
 
 function deleteEventFrom() {
   if (!occurrenceContext.value) return
   calendarStore.deleteFromOccurrence(occurrenceContext.value)
+  calendarStore.$history?.endCompound()
   closeDialog()
 }
 
@@ -412,6 +423,8 @@ watch([recurrenceEnabled, recurrenceInterval, recurrenceFrequency], () => {
 })
 watch(showDialog, (val, oldVal) => {
   if (oldVal && !val) {
+    // Closed (cancel, escape, outside click) -> end compound session
+    calendarStore.$history?.endCompound()
     if (dialogMode.value === 'create' && unsavedCreateId.value && !eventSaved.value) {
       if (calendarStore.events?.has(unsavedCreateId.value)) {
         calendarStore.deleteEvent(unsavedCreateId.value)
diff --git a/src/components/EventOverlay.vue b/src/components/EventOverlay.vue
index 82f5569..2ef3c9f 100644
--- a/src/components/EventOverlay.vue
+++ b/src/components/EventOverlay.vue
@@ -154,8 +154,13 @@ function startLocalDrag(init, evt) {
     anchorOffset,
     originSpanDays: spanDays,
     eventMoved: false,
+    tentativeStart: init.startDate,
+    tentativeEnd: init.endDate,
   }
 
+  // Begin compound history session (single snapshot after drag completes)
+  store.$history?.beginCompound()
+
   // Capture pointer events globally
   if (evt.currentTarget && evt.pointerId !== undefined) {
     try {
@@ -211,7 +216,18 @@ function onDragPointerMove(e) {
 
   const [ns, ne] = computeTentativeRangeFromPointer(st, hit.date)
   if (!ns || !ne) return
-  applyRangeDuringDrag(st, ns, ne)
+  // Only proceed if changed
+  if (ns === st.tentativeStart && ne === st.tentativeEnd) return
+  st.tentativeStart = ns
+  st.tentativeEnd = ne
+  // Real-time update only for non-virtual events (avoid repeated split operations)
+  if (!st.isVirtual) {
+    applyRangeDuringDrag(
+      { id: st.id, isVirtual: st.isVirtual, mode: st.mode, startDate: ns, endDate: ne },
+      ns,
+      ne,
+    )
+  }
 }
 
 function onDragPointerUp(e) {
@@ -228,6 +244,8 @@ function onDragPointerUp(e) {
   }
 
   const moved = !!st.eventMoved
+  const finalStart = st.tentativeStart
+  const finalEnd = st.tentativeEnd
   dragState.value = null
 
   window.removeEventListener('pointermove', onDragPointerMove)
@@ -235,11 +253,27 @@ function onDragPointerUp(e) {
   window.removeEventListener('pointercancel', onDragPointerUp)
 
   if (moved) {
+    // Apply final mutation if virtual (we deferred) or if non-virtual no further change (rare)
+    if (st.isVirtual) {
+      applyRangeDuringDrag(
+        {
+          id: st.id,
+          isVirtual: st.isVirtual,
+          mode: st.mode,
+          startDate: finalStart,
+          endDate: finalEnd,
+        },
+        finalStart,
+        finalEnd,
+      )
+    }
     justDragged.value = true
     setTimeout(() => {
       justDragged.value = false
     }, 120)
   }
+  // End compound session (snapshot if changed)
+  store.$history?.endCompound()
 }
 
 function computeTentativeRangeFromPointer(st, dropDateStr) {
diff --git a/src/main.js b/src/main.js
index c74fed5..82ac165 100644
--- a/src/main.js
+++ b/src/main.js
@@ -3,13 +3,16 @@ import './assets/calendar.css'
 import { createApp } from 'vue'
 import { createPinia } from 'pinia'
 import piniaPluginPersistedstate from 'pinia-plugin-persistedstate'
+import { calendarHistory } from '@/plugins/calendarHistory'
 
 import App from './App.vue'
 
 const app = createApp(App)
 
 const pinia = createPinia()
+// Order: persistence first so snapshots recorded by undo reflect already-hydrated state
 pinia.use(piniaPluginPersistedstate)
+pinia.use(calendarHistory)
 app.use(pinia)
 
 app.mount('#app')
diff --git a/src/plugins/calendarHistory.js b/src/plugins/calendarHistory.js
new file mode 100644
index 0000000..e74c544
--- /dev/null
+++ b/src/plugins/calendarHistory.js
@@ -0,0 +1,200 @@
+// Custom lightweight undo/redo specifically for calendar store with Map support
+// Adds store.$history = { undo(), redo(), canUndo, canRedo, clear(), pushManual() }
+// Wraps action calls to create history entries only for meaningful mutations.
+
+function deepCloneCalendarState(raw) {
+  // We only need to snapshot keys we care about; omit volatile fields
+  const { today, events, config, weekend } = raw
+  return {
+    today,
+    weekend: Array.isArray(weekend) ? [...weekend] : weekend,
+    config: JSON.parse(JSON.stringify(config)),
+    events: new Map([...events].map(([k, v]) => [k, { ...v }])),
+  }
+}
+
+function restoreCalendarState(store, snap) {
+  store.today = snap.today
+  store.weekend = Array.isArray(snap.weekend) ? [...snap.weekend] : snap.weekend
+  store.config = JSON.parse(JSON.stringify(snap.config))
+  store.events = new Map([...snap.events].map(([k, v]) => [k, { ...v }]))
+  store.eventsMutation = (store.eventsMutation + 1) % 1_000_000_000
+}
+
+export function calendarHistory({ store }) {
+  if (store.$id !== 'calendar') return
+
+  const max = 100 // history depth limit
+  const history = [] // past states
+  let pointer = -1 // index of current state in history
+  let isRestoring = false
+  let lastSerialized = null
+  // Compound editing session (e.g. event dialog) flags
+  let compoundActive = false
+  let compoundBaseSig = null
+  let compoundChanged = false
+
+  function serializeForComparison() {
+    const evCount = store.events instanceof Map ? store.events.size : 0
+    const em = store.eventsMutation || 0
+    return `${em}|${evCount}|${store.today}|${JSON.stringify(store.config)}`
+  }
+
+  function pushSnapshot() {
+    if (isRestoring) return
+    const sig = serializeForComparison()
+    if (sig === lastSerialized) return
+    // Drop any redo branch
+    if (pointer < history.length - 1) history.splice(pointer + 1)
+    history.push(deepCloneCalendarState(store))
+    if (history.length > max) history.shift()
+    pointer = history.length - 1
+    lastSerialized = sig
+    bumpIndicators()
+    // console.log('[history] pushed', pointer, sig)
+  }
+
+  function bumpIndicators() {
+    if (typeof store.historyTick === 'number') {
+      store.historyTick = (store.historyTick + 1) % 1_000_000_000
+    }
+    if (typeof store.historyCanUndo === 'boolean') {
+      store.historyCanUndo = pointer > 0
+    }
+    if (typeof store.historyCanRedo === 'boolean') {
+      store.historyCanRedo = pointer >= 0 && pointer < history.length - 1
+    }
+  }
+
+  function markPotentialChange() {
+    if (isRestoring) return
+    if (compoundActive) {
+      const sig = serializeForComparison()
+      if (sig !== compoundBaseSig) compoundChanged = true
+      return
+    }
+    pushSnapshot()
+  }
+
+  function beginCompound() {
+    if (compoundActive) return
+    compoundActive = true
+    compoundBaseSig = serializeForComparison()
+    compoundChanged = false
+  }
+  function endCompound() {
+    if (!compoundActive) return
+    const finalSig = serializeForComparison()
+    const changed = compoundChanged || finalSig !== compoundBaseSig
+    compoundActive = false
+    compoundBaseSig = null
+    if (changed) pushSnapshot()
+    else bumpIndicators() // session ended without change – still refresh flags
+  }
+
+  function undo() {
+    // Ensure any active compound changes are finalized before moving back
+    if (compoundActive) endCompound()
+    else {
+      // If current state differs from last snapshot, push it so redo can restore it
+      const curSig = serializeForComparison()
+      if (curSig !== lastSerialized) pushSnapshot()
+    }
+    if (pointer <= 0) return
+    pointer--
+    isRestoring = true
+    try {
+      restoreCalendarState(store, history[pointer])
+      lastSerialized = serializeForComparison()
+    } finally {
+      isRestoring = false
+    }
+    bumpIndicators()
+  }
+
+  function redo() {
+    if (compoundActive) endCompound()
+    else {
+      const curSig = serializeForComparison()
+      if (curSig !== lastSerialized) pushSnapshot()
+    }
+    if (pointer >= history.length - 1) return
+    pointer++
+    isRestoring = true
+    try {
+      restoreCalendarState(store, history[pointer])
+      lastSerialized = serializeForComparison()
+    } finally {
+      isRestoring = false
+    }
+    bumpIndicators()
+  }
+
+  function clear() {
+    history.length = 0
+    pointer = -1
+    lastSerialized = null
+    bumpIndicators()
+  }
+
+  // Wrap selected mutating actions to push snapshot AFTER they run if state changed.
+  const actionNames = [
+    'createEvent',
+    'deleteEvent',
+    'deleteFirstOccurrence',
+    'deleteSingleOccurrence',
+    'deleteFromOccurrence',
+    'setEventRange',
+    'splitMoveVirtualOccurrence',
+    'splitRepeatSeries',
+    '_terminateRepeatSeriesAtIndex',
+    'toggleHolidays',
+    'initializeHolidays',
+  ]
+
+  for (const name of actionNames) {
+    if (typeof store[name] === 'function') {
+      const original = store[name].bind(store)
+      store[name] = (...args) => {
+        const beforeSig = serializeForComparison()
+        const result = original(...args)
+        const afterSig = serializeForComparison()
+        if (afterSig !== beforeSig) markPotentialChange()
+        return result
+      }
+    }
+  }
+
+  // Capture direct property edits (e.g., deep field edits signaled via touchEvents())
+  store.$subscribe((mutation, _state) => {
+    if (mutation.storeId !== 'calendar') return
+    markPotentialChange()
+  })
+
+  // Initial snapshot after hydration (next microtask to let persistence load)
+  Promise.resolve().then(() => pushSnapshot())
+
+  store.$history = {
+    undo,
+    redo,
+    clear,
+    pushManual: pushSnapshot,
+    beginCompound,
+    endCompound,
+    flush() {
+      pushSnapshot()
+    },
+    get canUndo() {
+      return pointer > 0
+    },
+    get canRedo() {
+      return pointer >= 0 && pointer < history.length - 1
+    },
+    get compoundActive() {
+      return compoundActive
+    },
+    _debug() {
+      return { pointer, length: history.length }
+    },
+  }
+}
diff --git a/src/plugins/calendarUndoNormalize.js b/src/plugins/calendarUndoNormalize.js
new file mode 100644
index 0000000..af72c75
--- /dev/null
+++ b/src/plugins/calendarUndoNormalize.js
@@ -0,0 +1,57 @@
+// Pinia plugin to ensure calendar store keeps Map for events after undo/redo snapshots
+export function calendarUndoNormalize({ store }) {
+  if (store.$id !== 'calendar') return
+
+  function fixEvents() {
+    const evs = store.events
+    if (evs instanceof Map) return
+    // If serialized form { __map: true, data: [...] }
+    if (evs && evs.__map && Array.isArray(evs.data)) {
+      store.events = new Map(evs.data)
+      return
+    }
+    // If an array of [k,v]
+    if (Array.isArray(evs) && evs.every((x) => Array.isArray(x) && x.length === 2)) {
+      store.events = new Map(evs)
+      return
+    }
+    // If plain object, convert own enumerable props
+    if (evs && typeof evs === 'object') {
+      store.events = new Map(Object.entries(evs))
+    }
+  }
+
+  // Patch undo/redo if present (after pinia-undo is installed)
+  const patchFns = ['undo', 'redo']
+  for (const fn of patchFns) {
+    if (typeof store[fn] === 'function') {
+      const original = store[fn].bind(store)
+      store[fn] = (...args) => {
+        console.log(`[calendar history] ${fn} invoked`)
+        const beforeType = store.events && store.events.constructor && store.events.constructor.name
+        const out = original(...args)
+        const afterRawType =
+          store.events && store.events.constructor && store.events.constructor.name
+        fixEvents()
+        const finalType = store.events && store.events.constructor && store.events.constructor.name
+        let size = null
+        try {
+          if (store.events instanceof Map) size = store.events.size
+          else if (Array.isArray(store.events)) size = store.events.length
+        } catch {}
+        console.log(
+          `[calendar history] ${fn} types: before=${beforeType} afterRaw=${afterRawType} final=${finalType} size=${size}`,
+        )
+        return out
+      }
+    }
+  }
+
+  // Also watch all mutations (includes direct assigns and action commits)
+  store.$subscribe(() => {
+    fixEvents()
+  })
+
+  // Initial sanity
+  fixEvents()
+}
diff --git a/src/stores/CalendarStore.js b/src/stores/CalendarStore.js
index e5232f5..1884a46 100644
--- a/src/stores/CalendarStore.js
+++ b/src/stores/CalendarStore.js
@@ -18,6 +18,10 @@ export const useCalendarStore = defineStore('calendar', {
     // Lightweight mutation counter so views can rebuild in a throttled / idle way
     // without tracking deep reactivity on every event object.
     eventsMutation: 0,
+    // Incremented internally by history plugin to force reactive updates for canUndo/canRedo
+    historyTick: 0,
+    historyCanUndo: false,
+    historyCanRedo: false,
     weekend: getLocaleWeekendDays(),
     _holidayConfigSignature: null,
     _holidaysInitialized: false,