From 0928b4cd7f6f2a99e99302440dfff7f1dad5a00e Mon Sep 17 00:00:00 2001
From: vkpdeveloper <vaibhavpathak9984@gmail.com>
Date: Fri, 6 Nov 2026 01:24:30 +0530
Subject: [PATCH 1/2] fix(provider-utils): read offset-less event times in
 their own time zone

eventTimeToInstant parsed a dateTime without an offset with Date.parse,
so it used the host's zone and ignored timeZone. The mock calendar
then reported busy times hours off wherever the host zone differed
from the event's.
---
 .changeset/local-event-times.md                |  6 ++++++
 packages/provider-utils/src/time/event-time.ts | 11 ++++++++---
 packages/provider-utils/src/time/time.test.ts  | 10 ++++++++++
 3 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/local-event-times.md

diff --git a/.changeset/local-event-times.md b/.changeset/local-event-times.md
new file mode 100644
index 0000000..07c72c2
--- /dev/null
+++ b/.changeset/local-event-times.md
@@ -0,0 +1,6 @@
+---
+'@cal-sdk/provider-utils': patch
+'@cal-sdk/mock': patch
+---
+
+Event times without an offset, such as `{ dateTime: '2026-11-09T10:00:00', timeZone: 'Europe/Berlin' }`, are read in their own time zone instead of the machine's. This fixes busy times, listing windows and recurrence expansion in the mock calendar.
diff --git a/packages/provider-utils/src/time/event-time.ts b/packages/provider-utils/src/time/event-time.ts
index 644c21b..f44edcc 100644
--- a/packages/provider-utils/src/time/event-time.ts
+++ b/packages/provider-utils/src/time/event-time.ts
@@ -10,11 +10,16 @@ export function isAllDay(time: EventTimeV1): time is Extract<EventTimeV1, { date
 /**
  * The instant an event time refers to, in epoch milliseconds.
  *
- * All-day dates have no instant of their own: they start at midnight in
- * `allDayTimeZone` (usually the calendar's zone), UTC when omitted.
+ * A `dateTime` without an offset is a wall-clock time in its `timeZone`, never in the
+ * zone of the machine running the code. All-day dates have no instant of their own:
+ * they start at midnight in `allDayTimeZone` (usually the calendar's zone), UTC when
+ * omitted.
  */
 export function eventTimeToInstant(time: EventTimeV1, allDayTimeZone = 'UTC'): number {
-  if (!isAllDay(time)) return Date.parse(time.dateTime);
+  if (!isAllDay(time)) {
+    const wallClock = parseLocalDateTime(time.dateTime);
+    return wallClock ? localToInstant(wallClock, time.timeZone) : Date.parse(time.dateTime);
+  }
   const local = parseLocalDateTime(time.date);
   if (!local) return Number.NaN;
   return localToInstant(local, allDayTimeZone);
diff --git a/packages/provider-utils/src/time/time.test.ts b/packages/provider-utils/src/time/time.test.ts
index a0aa6d1..ffc45cc 100644
--- a/packages/provider-utils/src/time/time.test.ts
+++ b/packages/provider-utils/src/time/time.test.ts
@@ -115,6 +115,16 @@ describe('event time', () => {
     expect(eventTimeToInstant({ date: '2026-11-03' })).toBe(Date.parse('2026-11-03T00:00:00Z'));
   });
 
+  it('reads a date-time without an offset in its own time zone, not the host zone', () => {
+    expect(
+      eventTimeToInstant({ dateTime: '2026-11-09T10:00:00', timeZone: 'Europe/Berlin' }),
+    ).toBe(Date.parse('2026-11-09T09:00:00Z'));
+    // Daylight saving time in New York.
+    expect(
+      eventTimeToInstant({ dateTime: '2026-07-01T09:30', timeZone: 'America/New_York' }),
+    ).toBe(Date.parse('2026-07-01T13:30:00Z'));
+  });
+
   it('adds days across month and year ends', () => {
     expect(addDaysToDate('2026-12-31', 1)).toBe('2027-01-01');
     expect(addDaysToDate('2028-03-01', -1)).toBe('2028-02-29');

From 34020f6446e014eabd147b1fec05376de8638f18 Mon Sep 17 00:00:00 2001
From: vkpdeveloper <vaibhavpathak9984@gmail.com>
Date: Fri, 6 Nov 2026 01:29:12 +0530
Subject: [PATCH 2/2] style: format the local time test

---
 packages/provider-utils/src/time/time.test.ts | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/packages/provider-utils/src/time/time.test.ts b/packages/provider-utils/src/time/time.test.ts
index ffc45cc..784d467 100644
--- a/packages/provider-utils/src/time/time.test.ts
+++ b/packages/provider-utils/src/time/time.test.ts
@@ -116,13 +116,13 @@ describe('event time', () => {
   });
 
   it('reads a date-time without an offset in its own time zone, not the host zone', () => {
-    expect(
-      eventTimeToInstant({ dateTime: '2026-11-09T10:00:00', timeZone: 'Europe/Berlin' }),
-    ).toBe(Date.parse('2026-11-09T09:00:00Z'));
+    expect(eventTimeToInstant({ dateTime: '2026-11-09T10:00:00', timeZone: 'Europe/Berlin' })).toBe(
+      Date.parse('2026-11-09T09:00:00Z'),
+    );
     // Daylight saving time in New York.
-    expect(
-      eventTimeToInstant({ dateTime: '2026-07-01T09:30', timeZone: 'America/New_York' }),
-    ).toBe(Date.parse('2026-07-01T13:30:00Z'));
+    expect(eventTimeToInstant({ dateTime: '2026-07-01T09:30', timeZone: 'America/New_York' })).toBe(
+      Date.parse('2026-07-01T13:30:00Z'),
+    );
   });
 
   it('adds days across month and year ends', () => {