From 36206c85f8c57cc901dbf2b1e2f78e3fe0ecc3a9 Mon Sep 17 00:00:00 2001
From: jasonk55 <jasonkuo55@gmail.com>
Date: Wed, 24 Sep 2025 00:17:28 -0400
Subject: [PATCH 01/16]  working fix for start date bug

---
 .../controllers/work-packages.controllers.ts  |  22 +++-
 .../src/services/work-packages.services.ts    | 108 ++++++++++++++++--
 src/frontend/src/apis/work-packages.api.ts    |  12 +-
 3 files changed, 125 insertions(+), 17 deletions(-)

diff --git a/src/backend/src/controllers/work-packages.controllers.ts b/src/backend/src/controllers/work-packages.controllers.ts
index 09981f66ac..f0174cdf1e 100644
--- a/src/backend/src/controllers/work-packages.controllers.ts
+++ b/src/backend/src/controllers/work-packages.controllers.ts
@@ -44,7 +44,8 @@ export default class WorkPackagesController {
   // Create a work package with the given details
   static async createWorkPackage(req: Request, res: Response, next: NextFunction) {
     try {
-      const { name, crId, startDate, duration, blockedBy, descriptionBullets, projectWbsNum } = req.body;
+      const { name, crId, startDate, duration, blockedBy, descriptionBullets, projectWbsNum, clientOffsetMinutes } =
+        req.body;
       let { stage } = req.body;
       if (stage === 'NONE') {
         stage = null;
@@ -59,7 +60,8 @@ export default class WorkPackagesController {
         blockedBy,
         descriptionBullets,
         projectWbsNum,
-        req.organization
+        req.organization,
+        typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
       );
 
       res.status(200).json(workPackage);
@@ -71,7 +73,18 @@ export default class WorkPackagesController {
   // Edit a work package to the given specifications
   static async editWorkPackage(req: Request, res: Response, next: NextFunction) {
     try {
-      const { workPackageId, name, crId, startDate, duration, blockedBy, descriptionBullets, leadId, managerId } = req.body;
+      const {
+        workPackageId,
+        name,
+        crId,
+        startDate,
+        duration,
+        blockedBy,
+        descriptionBullets,
+        leadId,
+        managerId,
+        clientOffsetMinutes
+      } = req.body;
       let { stage } = req.body;
       if (stage === 'NONE') {
         stage = null;
@@ -88,7 +101,8 @@ export default class WorkPackagesController {
         descriptionBullets,
         leadId,
         managerId,
-        req.organization
+        req.organization,
+        typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
       );
       res.status(200).json({ message: 'Work package updated successfully' });
     } catch (error: unknown) {
diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index c804088b06..bdfa931a34 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -37,6 +37,73 @@ import { userHasPermission } from '../utils/users.utils';
 
 /** Service layer containing logic for work package controller functions. */
 export default class WorkPackagesService {
+  /** Lightweight structured logger for date normalization during create/edit. */
+  private static logDateNormalization(
+    context: 'create' | 'edit',
+    details: {
+      userId: string;
+      organizationId: string;
+      rawInput: string;
+      clientOffsetMinutes?: number;
+      normalized: Date;
+      workPackageId?: string;
+      projectRef?: string; // e.g., "car.project.wp#"
+    }
+  ) {
+    try {
+      const { userId, organizationId, rawInput, clientOffsetMinutes, normalized, workPackageId, projectRef } = details;
+      // Keep it concise but useful for debugging timezone issues
+      console.log(
+        `WP ${context} date normalization`,
+        {
+          userId,
+          organizationId,
+          rawInput,
+          clientOffsetMinutes,
+          normalizedISO: normalized.toISOString(),
+          normalizedLocal: normalized.toString(),
+          workPackageId,
+          projectRef
+        }
+      );
+    } catch {
+      // never let logging break the flow
+    }
+  }
+  /**
+   * Normalize an input date string to the user's local midnight converted to UTC.
+   * - If clientOffsetMinutes is provided (minutes from UTC, same sign as Date.getTimezoneOffset), we interpret day boundaries in that local timezone.
+   * - For date-only inputs (YYYY-MM-DD or YYYY/MM/DD): use 00:00 local on that date, then convert to the corresponding UTC instant.
+   * - For timestamp inputs: derive the local calendar day of that instant in user's timezone, then normalize to that day's 00:00 local converted to UTC.
+   * - If clientOffsetMinutes is not provided, default to UTC day boundaries (00:00:00.000Z) for backwards compatibility.
+   */
+  private static toUtcMidnight(input: string, clientOffsetMinutes?: number): Date {
+    const dateOnly = input.match(/^(\d{4})[-/](\d{2})[-/](\d{2})$/);
+    const offsetMs = (clientOffsetMinutes ?? 0) * 60 * 1000;
+
+    // Helper: build a Date for local midnight converted to UTC using the offset
+    const toUtcFromLocalMidnight = (y: number, mZeroIdx: number, d: number) =>
+      new Date(Date.UTC(y, mZeroIdx, d, 0, 0, 0, 0) + offsetMs);
+
+    if (dateOnly) {
+      const y = Number(dateOnly[1]);
+      const m = Number(dateOnly[2]);
+      const d = Number(dateOnly[3]);
+      const normalized = toUtcFromLocalMidnight(y, m - 1, d);
+      return normalized;
+    }
+
+    const parsed = new Date(input);
+    if (isNaN(parsed.getTime())) throw new Error(`Invalid date input: ${input}`);
+
+    // Derive user's local calendar date by shifting the instant by the offset
+    const shifted = new Date(parsed.getTime() - offsetMs);
+    const y = shifted.getUTCFullYear();
+    const m = shifted.getUTCMonth();
+    const d = shifted.getUTCDate();
+    const normalized = toUtcFromLocalMidnight(y, m, d);
+    return normalized;
+  }
   /**
    * Retrieve all work packages, optionally filtered by query parameters.
    *
@@ -157,7 +224,8 @@ export default class WorkPackagesService {
     blockedBy: WbsNumber[],
     descriptionBullets: DescriptionBulletPreview[],
     projectWbsNum: WbsNumber,
-    organization: Organization
+    organization: Organization,
+    clientOffsetMinutes?: number
   ): Promise<WorkPackage> {
     if (await userHasPermission(user.userId, organization.organizationId, isGuest))
       throw new AccessDeniedGuestException('create work packages');
@@ -205,9 +273,17 @@ export default class WorkPackagesService {
         .map((element) => element.wbsElement.workPackageNumber)
         .reduce((prev, curr) => Math.max(prev, curr), 0) + 1;
 
-    // make the date object but add 12 hours so that the time isn't 00:00 to avoid timezone problems
-    const date = new Date(startDate.split('T')[0]);
-    date.setTime(date.getTime() + 12 * 60 * 60 * 1000);
+    // Normalize incoming startDate using user's local midnight converted to UTC when offset provided
+    const date = WorkPackagesService.toUtcMidnight(startDate, clientOffsetMinutes);
+    // Log normalization context for troubleshooting
+    WorkPackagesService.logDateNormalization('create', {
+      userId: user.userId,
+      organizationId: organization.organizationId,
+      rawInput: startDate,
+      clientOffsetMinutes,
+      normalized: date,
+      projectRef: `${carNumber}.${projectNumber}.${newWorkPackageNumber}`
+    });
 
     const changesToCreate = crId
       ? [
@@ -252,7 +328,7 @@ export default class WorkPackagesService {
       null,
       stage,
       null,
-      new Date(startDate),
+      date,
       null,
       duration,
       [],
@@ -307,7 +383,8 @@ export default class WorkPackagesService {
     descriptionBullets: DescriptionBulletPreview[],
     leadId: string | null,
     managerId: string | null,
-    organization: Organization
+    organization: Organization,
+    clientOffsetMinutes?: number
   ): Promise<WorkPackage> {
     const { userId } = user;
     // verify user is allowed to edit work packages
@@ -339,13 +416,24 @@ export default class WorkPackagesService {
 
     const blockedByElems = await validateBlockedBys(blockedBy, organization.organizationId);
 
+    // Normalize new startDate using user's local midnight converted to UTC when offset provided
+    const normalizedEdit = WorkPackagesService.toUtcMidnight(startDate, clientOffsetMinutes);
+    // Log normalization context for troubleshooting
+    WorkPackagesService.logDateNormalization('edit', {
+      userId,
+      organizationId: organization.organizationId,
+      rawInput: startDate,
+      clientOffsetMinutes,
+      normalized: normalizedEdit,
+      workPackageId
+    });
     const changes = await getWorkPackageChanges(
       originalWorkPackage.wbsElement.name,
       name,
       originalWorkPackage.stage,
       stage,
       originalWorkPackage.startDate,
-      new Date(startDate),
+      normalizedEdit,
       originalWorkPackage.duration,
       duration,
       originalWorkPackage.blockedBy,
@@ -360,10 +448,8 @@ export default class WorkPackagesService {
       wbsElementId,
       userId
     );
-
-    // make the date object but add 12 hours so that the time isn't 00:00 to avoid timezone problems
-    const date = new Date(startDate);
-    date.setTime(date.getTime() + 12 * 60 * 60 * 1000);
+    // Store at 00:00 UTC (canonical)
+    const date = normalizedEdit;
 
     // set the status of the wbs element to active if an edit is made to a completed version
     const status =
diff --git a/src/frontend/src/apis/work-packages.api.ts b/src/frontend/src/apis/work-packages.api.ts
index 390aca23b1..1d5ed68441 100644
--- a/src/frontend/src/apis/work-packages.api.ts
+++ b/src/frontend/src/apis/work-packages.api.ts
@@ -17,6 +17,8 @@ export interface WorkPackageApiInputs {
   crId?: string;
   blockedBy: WbsNumber[];
   descriptionBullets: DescriptionBulletPreview[];
+  /** Optional client timezone offset in minutes (same sign as Date.getTimezoneOffset). */
+  clientOffsetMinutes?: number;
 }
 
 export interface WorkPackageCreateArgs extends WorkPackageApiInputs {
@@ -53,8 +55,11 @@ export const getSingleWorkPackage = (wbsNum: WbsNumber) => {
  * @param payload Payload containing all the necessary data to create a work package.
  */
 export const createSingleWorkPackage = (payload: WorkPackageCreateArgs) => {
+  const clientOffsetMinutes =
+    typeof payload.clientOffsetMinutes === 'number' ? payload.clientOffsetMinutes : new Date().getTimezoneOffset();
   return axios.post<WorkPackage>(apiUrls.workPackagesCreate(), {
-    ...payload
+    ...payload,
+    clientOffsetMinutes
   });
 };
 
@@ -65,8 +70,11 @@ export const createSingleWorkPackage = (payload: WorkPackageCreateArgs) => {
  * @returns Promise that will resolve to either a success status code or a fail status code.
  */
 export const editWorkPackage = (payload: WorkPackageEditArgs) => {
+  const clientOffsetMinutes =
+    typeof payload.clientOffsetMinutes === 'number' ? payload.clientOffsetMinutes : new Date().getTimezoneOffset();
   return axios.post<{ message: string }>(apiUrls.workPackagesEdit(), {
-    ...payload
+    ...payload,
+    clientOffsetMinutes
   });
 };
 

From c3f8e64eb920ce18bff2b253a18f05aa23c48226 Mon Sep 17 00:00:00 2001
From: jasonk55 <jasonkuo55@gmail.com>
Date: Wed, 24 Sep 2025 00:24:18 -0400
Subject: [PATCH 02/16] #1192 fixed file versions

---
 .../src/services/work-packages.services.ts    | 51 -------------------
 1 file changed, 51 deletions(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index bdfa931a34..6e9c1c9164 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -37,39 +37,6 @@ import { userHasPermission } from '../utils/users.utils';
 
 /** Service layer containing logic for work package controller functions. */
 export default class WorkPackagesService {
-  /** Lightweight structured logger for date normalization during create/edit. */
-  private static logDateNormalization(
-    context: 'create' | 'edit',
-    details: {
-      userId: string;
-      organizationId: string;
-      rawInput: string;
-      clientOffsetMinutes?: number;
-      normalized: Date;
-      workPackageId?: string;
-      projectRef?: string; // e.g., "car.project.wp#"
-    }
-  ) {
-    try {
-      const { userId, organizationId, rawInput, clientOffsetMinutes, normalized, workPackageId, projectRef } = details;
-      // Keep it concise but useful for debugging timezone issues
-      console.log(
-        `WP ${context} date normalization`,
-        {
-          userId,
-          organizationId,
-          rawInput,
-          clientOffsetMinutes,
-          normalizedISO: normalized.toISOString(),
-          normalizedLocal: normalized.toString(),
-          workPackageId,
-          projectRef
-        }
-      );
-    } catch {
-      // never let logging break the flow
-    }
-  }
   /**
    * Normalize an input date string to the user's local midnight converted to UTC.
    * - If clientOffsetMinutes is provided (minutes from UTC, same sign as Date.getTimezoneOffset), we interpret day boundaries in that local timezone.
@@ -275,15 +242,6 @@ export default class WorkPackagesService {
 
     // Normalize incoming startDate using user's local midnight converted to UTC when offset provided
     const date = WorkPackagesService.toUtcMidnight(startDate, clientOffsetMinutes);
-    // Log normalization context for troubleshooting
-    WorkPackagesService.logDateNormalization('create', {
-      userId: user.userId,
-      organizationId: organization.organizationId,
-      rawInput: startDate,
-      clientOffsetMinutes,
-      normalized: date,
-      projectRef: `${carNumber}.${projectNumber}.${newWorkPackageNumber}`
-    });
 
     const changesToCreate = crId
       ? [
@@ -418,15 +376,6 @@ export default class WorkPackagesService {
 
     // Normalize new startDate using user's local midnight converted to UTC when offset provided
     const normalizedEdit = WorkPackagesService.toUtcMidnight(startDate, clientOffsetMinutes);
-    // Log normalization context for troubleshooting
-    WorkPackagesService.logDateNormalization('edit', {
-      userId,
-      organizationId: organization.organizationId,
-      rawInput: startDate,
-      clientOffsetMinutes,
-      normalized: normalizedEdit,
-      workPackageId
-    });
     const changes = await getWorkPackageChanges(
       originalWorkPackage.wbsElement.name,
       name,

From af942d8edf0268d17803054423e5e26838fbc8d8 Mon Sep 17 00:00:00 2001
From: jasonk55 <jasonkuo55@gmail.com>
Date: Wed, 24 Sep 2025 21:25:38 -0400
Subject: [PATCH 03/16] 1192 Date is the same anywhere

---
 .../src/services/work-packages.services.ts        | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index 6e9c1c9164..230a497bc1 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -40,28 +40,17 @@ export default class WorkPackagesService {
   /**
    * Normalize an input date string to the user's local midnight converted to UTC.
    * - If clientOffsetMinutes is provided (minutes from UTC, same sign as Date.getTimezoneOffset), we interpret day boundaries in that local timezone.
-   * - For date-only inputs (YYYY-MM-DD or YYYY/MM/DD): use 00:00 local on that date, then convert to the corresponding UTC instant.
-   * - For timestamp inputs: derive the local calendar day of that instant in user's timezone, then normalize to that day's 00:00 local converted to UTC.
+   * - Derive the local calendar day of that instant in user's timezone, then normalize to that day's 00:00 local converted to UTC.
    * - If clientOffsetMinutes is not provided, default to UTC day boundaries (00:00:00.000Z) for backwards compatibility.
    */
   private static toUtcMidnight(input: string, clientOffsetMinutes?: number): Date {
-    const dateOnly = input.match(/^(\d{4})[-/](\d{2})[-/](\d{2})$/);
     const offsetMs = (clientOffsetMinutes ?? 0) * 60 * 1000;
 
-    // Helper: build a Date for local midnight converted to UTC using the offset
+    // Build a Date for local midnight converted to UTC using the offset
     const toUtcFromLocalMidnight = (y: number, mZeroIdx: number, d: number) =>
       new Date(Date.UTC(y, mZeroIdx, d, 0, 0, 0, 0) + offsetMs);
 
-    if (dateOnly) {
-      const y = Number(dateOnly[1]);
-      const m = Number(dateOnly[2]);
-      const d = Number(dateOnly[3]);
-      const normalized = toUtcFromLocalMidnight(y, m - 1, d);
-      return normalized;
-    }
-
     const parsed = new Date(input);
-    if (isNaN(parsed.getTime())) throw new Error(`Invalid date input: ${input}`);
 
     // Derive user's local calendar date by shifting the instant by the offset
     const shifted = new Date(parsed.getTime() - offsetMs);

From e53ee7dde4e45eb6c33be9f2ea309ac14215b9dd Mon Sep 17 00:00:00 2001
From: jasonk55 <jasonkuo55@gmail.com>
Date: Wed, 24 Sep 2025 21:25:38 -0400
Subject: [PATCH 04/16] #1192 Date stays the same in all timezones

---
 .../src/services/work-packages.services.ts    | 49 ++++++++-----------
 1 file changed, 20 insertions(+), 29 deletions(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index 6e9c1c9164..0c69973c66 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -38,38 +38,29 @@ import { userHasPermission } from '../utils/users.utils';
 /** Service layer containing logic for work package controller functions. */
 export default class WorkPackagesService {
   /**
-   * Normalize an input date string to the user's local midnight converted to UTC.
-   * - If clientOffsetMinutes is provided (minutes from UTC, same sign as Date.getTimezoneOffset), we interpret day boundaries in that local timezone.
-   * - For date-only inputs (YYYY-MM-DD or YYYY/MM/DD): use 00:00 local on that date, then convert to the corresponding UTC instant.
-   * - For timestamp inputs: derive the local calendar day of that instant in user's timezone, then normalize to that day's 00:00 local converted to UTC.
-   * - If clientOffsetMinutes is not provided, default to UTC day boundaries (00:00:00.000Z) for backwards compatibility.
+   * Normalize an input date string to the canonical calendar day at UTC midnight.
+   *
+   * Behavior:
+   * - Treat the provided startDate as a calendar date (the date the user selected), not a moment-in-time.
+   * - Persist that calendar date at 00:00:00.000Z (UTC midnight) regardless of the user's timezone.
+   * - When viewed in a different timezone, this may render as the previous/next local day (expected by design).
+   *
+   * Notes:
+   * - clientOffsetMinutes is accepted for backward compatibility but intentionally ignored.
+   * - Supports common formats like YYYY-MM-DD (preferred), YYYY/MM/DD, and M/D/(YY|YYYY).
    */
-  private static toUtcMidnight(input: string, clientOffsetMinutes?: number): Date {
-    const dateOnly = input.match(/^(\d{4})[-/](\d{2})[-/](\d{2})$/);
-    const offsetMs = (clientOffsetMinutes ?? 0) * 60 * 1000;
-
-    // Helper: build a Date for local midnight converted to UTC using the offset
-    const toUtcFromLocalMidnight = (y: number, mZeroIdx: number, d: number) =>
-      new Date(Date.UTC(y, mZeroIdx, d, 0, 0, 0, 0) + offsetMs);
-
-    if (dateOnly) {
-      const y = Number(dateOnly[1]);
-      const m = Number(dateOnly[2]);
-      const d = Number(dateOnly[3]);
-      const normalized = toUtcFromLocalMidnight(y, m - 1, d);
-      return normalized;
-    }
+  private static toUtcMidnight(input: string, _clientOffsetMinutes?: number): Date {
+    // Helpers
+    const toUtcMidnight = (y: number, mZeroIdx: number, d: number) => new Date(Date.UTC(y, mZeroIdx, d, 0, 0, 0, 0));
 
     const parsed = new Date(input);
-    if (isNaN(parsed.getTime())) throw new Error(`Invalid date input: ${input}`);
-
-    // Derive user's local calendar date by shifting the instant by the offset
-    const shifted = new Date(parsed.getTime() - offsetMs);
-    const y = shifted.getUTCFullYear();
-    const m = shifted.getUTCMonth();
-    const d = shifted.getUTCDate();
-    const normalized = toUtcFromLocalMidnight(y, m, d);
-    return normalized;
+    if (!isNaN(parsed.getTime())) {
+      return toUtcMidnight(parsed.getUTCFullYear(), parsed.getUTCMonth(), parsed.getUTCDate());
+    }
+
+    // 6) If all parsing fails, default to "today" at UTC midnight
+    const now = new Date();
+    return toUtcMidnight(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate());
   }
   /**
    * Retrieve all work packages, optionally filtered by query parameters.

From ce10efba398ea70ef0be32057b1403ad1a38cec1 Mon Sep 17 00:00:00 2001
From: jasonk55 <jasonkuo55@gmail.com>
Date: Wed, 24 Sep 2025 16:42:57 -0400
Subject: [PATCH 05/16] #1192 Cleaned up controller methods

---
 .../src/services/work-packages.services.ts    | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index 230a497bc1..8f1107efcd 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -47,19 +47,16 @@ export default class WorkPackagesService {
     const offsetMs = (clientOffsetMinutes ?? 0) * 60 * 1000;
 
     // Build a Date for local midnight converted to UTC using the offset
-    const toUtcFromLocalMidnight = (y: number, mZeroIdx: number, d: number) =>
-      new Date(Date.UTC(y, mZeroIdx, d, 0, 0, 0, 0) + offsetMs);
+    const toUtcFromLocalMidnight = (y: number, m: number, d: number) => new Date(Date.UTC(y, m, d, 0, 0, 0, 0) + offsetMs);
 
     const parsed = new Date(input);
 
     // Derive user's local calendar date by shifting the instant by the offset
     const shifted = new Date(parsed.getTime() - offsetMs);
-    const y = shifted.getUTCFullYear();
-    const m = shifted.getUTCMonth();
-    const d = shifted.getUTCDate();
-    const normalized = toUtcFromLocalMidnight(y, m, d);
+    const normalized = toUtcFromLocalMidnight(shifted.getUTCFullYear(), shifted.getUTCMonth(), shifted.getUTCDate());
     return normalized;
   }
+
   /**
    * Retrieve all work packages, optionally filtered by query parameters.
    *
@@ -230,7 +227,10 @@ export default class WorkPackagesService {
         .reduce((prev, curr) => Math.max(prev, curr), 0) + 1;
 
     // Normalize incoming startDate using user's local midnight converted to UTC when offset provided
-    const date = WorkPackagesService.toUtcMidnight(startDate, clientOffsetMinutes);
+    const date = WorkPackagesService.toUtcMidnight(
+      startDate,
+      typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
+    );
 
     const changesToCreate = crId
       ? [
@@ -364,7 +364,10 @@ export default class WorkPackagesService {
     const blockedByElems = await validateBlockedBys(blockedBy, organization.organizationId);
 
     // Normalize new startDate using user's local midnight converted to UTC when offset provided
-    const normalizedEdit = WorkPackagesService.toUtcMidnight(startDate, clientOffsetMinutes);
+    const normalizedEdit = WorkPackagesService.toUtcMidnight(
+      startDate,
+      typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
+    );
     const changes = await getWorkPackageChanges(
       originalWorkPackage.wbsElement.name,
       name,

From 57e484032bb4647aefbc0a0e6983376f20ab6294 Mon Sep 17 00:00:00 2001
From: jasonk55 <jasonkuo55@gmail.com>
Date: Wed, 24 Sep 2025 19:01:07 -0400
Subject: [PATCH 06/16] #1192 Fixed controllers file

---
 src/backend/src/controllers/work-packages.controllers.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/src/controllers/work-packages.controllers.ts b/src/backend/src/controllers/work-packages.controllers.ts
index f0174cdf1e..2f4cde41d1 100644
--- a/src/backend/src/controllers/work-packages.controllers.ts
+++ b/src/backend/src/controllers/work-packages.controllers.ts
@@ -61,7 +61,7 @@ export default class WorkPackagesController {
         descriptionBullets,
         projectWbsNum,
         req.organization,
-        typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
+        clientOffsetMinutes
       );
 
       res.status(200).json(workPackage);
@@ -102,7 +102,7 @@ export default class WorkPackagesController {
         leadId,
         managerId,
         req.organization,
-        typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
+        clientOffsetMinutes
       );
       res.status(200).json({ message: 'Work package updated successfully' });
     } catch (error: unknown) {

From 1a9095c3b200c5717246521f236a2b1501d6ec64 Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Thu, 16 Oct 2025 19:38:15 -0400
Subject: [PATCH 07/16] dayjs

---
 src/backend/package.json                      |  1 +
 .../src/services/work-packages.services.ts    | 30 +++++++++++--------
 yarn.lock                                     |  8 +++++
 3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/backend/package.json b/src/backend/package.json
index 92ec84d984..698e42e182 100644
--- a/src/backend/package.json
+++ b/src/backend/package.json
@@ -22,6 +22,7 @@
     "concat-stream": "^2.0.0",
     "cookie-parser": "^1.4.5",
     "cors": "^2.8.5",
+    "dayjs": "^1.11.18",
     "decimal.js": "^10.4.3",
     "dotenv": "^16.0.1",
     "express": "^5.0.0",
diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index 8f1107efcd..a9fb6b68c5 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -26,6 +26,8 @@ import workPackageTransformer from '../transformers/work-packages.transformer';
 import { updateBlocking, validateChangeRequestAccepted } from '../utils/change-requests.utils';
 import { sendSlackUpcomingDeadlineNotification } from '../utils/slack.utils';
 import { getWorkPackageChanges } from '../utils/changes.utils';
+import dayjs from 'dayjs';
+import utc from 'dayjs/plugin/utc';
 import {
   DescriptionBulletDestination,
   addRawDescriptionBullets,
@@ -35,26 +37,30 @@ import { getBlockingWorkPackages, validateBlockedBys } from '../utils/work-packa
 import { getDescriptionBulletQueryArgs } from '../prisma-query-args/description-bullets.query-args';
 import { userHasPermission } from '../utils/users.utils';
 
+// Initialize Day.js plugins for timezone handling
+dayjs.extend(utc);
+
 /** Service layer containing logic for work package controller functions. */
 export default class WorkPackagesService {
   /**
-   * Normalize an input date string to the user's local midnight converted to UTC.
-   * - If clientOffsetMinutes is provided (minutes from UTC, same sign as Date.getTimezoneOffset), we interpret day boundaries in that local timezone.
-   * - Derive the local calendar day of that instant in user's timezone, then normalize to that day's 00:00 local converted to UTC.
-   * - If clientOffsetMinutes is not provided, default to UTC day boundaries (00:00:00.000Z) for backwards compatibility.
+   * Normalize an input date string to the user's local midnight converted to UTC
+   *
+   * @param input - The date string to normalize
+   * @param clientOffsetMinutes - client timezone offset in minutes
+   * @returns date representing midnight
    */
   private static toUtcMidnight(input: string, clientOffsetMinutes?: number): Date {
-    const offsetMs = (clientOffsetMinutes ?? 0) * 60 * 1000;
+    if (clientOffsetMinutes === undefined) {
+      return dayjs(input).utc().startOf('day').toDate();
+    }
 
-    // Build a Date for local midnight converted to UTC using the offset
-    const toUtcFromLocalMidnight = (y: number, m: number, d: number) => new Date(Date.UTC(y, m, d, 0, 0, 0, 0) + offsetMs);
+    const inputDate = dayjs(input);
+    const userLocalDate = inputDate.subtract(clientOffsetMinutes, 'minutes');
 
-    const parsed = new Date(input);
+    const userMidnight = userLocalDate.startOf('day');
+    const utcMidnight = userMidnight.add(clientOffsetMinutes, 'minutes');
 
-    // Derive user's local calendar date by shifting the instant by the offset
-    const shifted = new Date(parsed.getTime() - offsetMs);
-    const normalized = toUtcFromLocalMidnight(shifted.getUTCFullYear(), shifted.getUTCMonth(), shifted.getUTCDate());
-    return normalized;
+    return utcMidnight.toDate();
   }
 
   /**
diff --git a/yarn.lock b/yarn.lock
index 3052d16cf3..c93d2b252e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6911,6 +6911,7 @@ __metadata:
     concat-stream: ^2.0.0
     cookie-parser: ^1.4.5
     cors: ^2.8.5
+    dayjs: ^1.11.18
     decimal.js: ^10.4.3
     dotenv: ^16.0.1
     express: ^5.0.0
@@ -8543,6 +8544,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"dayjs@npm:^1.11.18":
+  version: 1.11.18
+  resolution: "dayjs@npm:1.11.18"
+  checksum: cc90054bad30ab011417a7a474b2ffa70e7a28ca6f834d7e86fe53a408a40a14c174f26155072628670e9eda4c48c4ed0d847d2edf83d47c0bfb78be15bbf2dd
+  languageName: node
+  linkType: hard
+
 "debug@npm:2.6.9, debug@npm:^2.6.0, debug@npm:^2.6.1":
   version: 2.6.9
   resolution: "debug@npm:2.6.9"

From fe522fa83f02d0719ed2f769da721a830bb2548c Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Thu, 16 Oct 2025 19:39:06 -0400
Subject: [PATCH 08/16] prettier

---
 src/backend/src/services/work-packages.services.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index a9fb6b68c5..d4037b0e54 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -37,7 +37,6 @@ import { getBlockingWorkPackages, validateBlockedBys } from '../utils/work-packa
 import { getDescriptionBulletQueryArgs } from '../prisma-query-args/description-bullets.query-args';
 import { userHasPermission } from '../utils/users.utils';
 
-// Initialize Day.js plugins for timezone handling
 dayjs.extend(utc);
 
 /** Service layer containing logic for work package controller functions. */

From bbe0d3c4143fc35b2f07dffd343c3c1a61a712a6 Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Thu, 16 Oct 2025 20:06:41 -0400
Subject: [PATCH 09/16] getting rid of the offset

---
 .../controllers/work-packages.controllers.ts  | 22 ++--------
 .../src/services/work-packages.services.ts    | 40 +++++--------------
 src/frontend/package.json                     |  2 +-
 src/frontend/src/apis/work-packages.api.ts    | 16 +-------
 src/frontend/src/utils/datetime.utils.ts      | 10 +++--
 yarn.lock                                     |  9 +----
 6 files changed, 25 insertions(+), 74 deletions(-)

diff --git a/src/backend/src/controllers/work-packages.controllers.ts b/src/backend/src/controllers/work-packages.controllers.ts
index 2f4cde41d1..09981f66ac 100644
--- a/src/backend/src/controllers/work-packages.controllers.ts
+++ b/src/backend/src/controllers/work-packages.controllers.ts
@@ -44,8 +44,7 @@ export default class WorkPackagesController {
   // Create a work package with the given details
   static async createWorkPackage(req: Request, res: Response, next: NextFunction) {
     try {
-      const { name, crId, startDate, duration, blockedBy, descriptionBullets, projectWbsNum, clientOffsetMinutes } =
-        req.body;
+      const { name, crId, startDate, duration, blockedBy, descriptionBullets, projectWbsNum } = req.body;
       let { stage } = req.body;
       if (stage === 'NONE') {
         stage = null;
@@ -60,8 +59,7 @@ export default class WorkPackagesController {
         blockedBy,
         descriptionBullets,
         projectWbsNum,
-        req.organization,
-        clientOffsetMinutes
+        req.organization
       );
 
       res.status(200).json(workPackage);
@@ -73,18 +71,7 @@ export default class WorkPackagesController {
   // Edit a work package to the given specifications
   static async editWorkPackage(req: Request, res: Response, next: NextFunction) {
     try {
-      const {
-        workPackageId,
-        name,
-        crId,
-        startDate,
-        duration,
-        blockedBy,
-        descriptionBullets,
-        leadId,
-        managerId,
-        clientOffsetMinutes
-      } = req.body;
+      const { workPackageId, name, crId, startDate, duration, blockedBy, descriptionBullets, leadId, managerId } = req.body;
       let { stage } = req.body;
       if (stage === 'NONE') {
         stage = null;
@@ -101,8 +88,7 @@ export default class WorkPackagesController {
         descriptionBullets,
         leadId,
         managerId,
-        req.organization,
-        clientOffsetMinutes
+        req.organization
       );
       res.status(200).json({ message: 'Work package updated successfully' });
     } catch (error: unknown) {
diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index d4037b0e54..499f95d812 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -43,23 +43,11 @@ dayjs.extend(utc);
 export default class WorkPackagesService {
   /**
    * Normalize an input date string to the user's local midnight converted to UTC
-   *
-   * @param input - The date string to normalize
-   * @param clientOffsetMinutes - client timezone offset in minutes
-   * @returns date representing midnight
+   * @param input - The date string to normalize 
+   * @returns date object representing midnight UTC
    */
-  private static toUtcMidnight(input: string, clientOffsetMinutes?: number): Date {
-    if (clientOffsetMinutes === undefined) {
-      return dayjs(input).utc().startOf('day').toDate();
-    }
-
-    const inputDate = dayjs(input);
-    const userLocalDate = inputDate.subtract(clientOffsetMinutes, 'minutes');
-
-    const userMidnight = userLocalDate.startOf('day');
-    const utcMidnight = userMidnight.add(clientOffsetMinutes, 'minutes');
-
-    return utcMidnight.toDate();
+  private static toUtcMidnight(input: string): Date {
+    return dayjs(input).utc().startOf('day').toDate();
   }
 
   /**
@@ -182,8 +170,7 @@ export default class WorkPackagesService {
     blockedBy: WbsNumber[],
     descriptionBullets: DescriptionBulletPreview[],
     projectWbsNum: WbsNumber,
-    organization: Organization,
-    clientOffsetMinutes?: number
+    organization: Organization
   ): Promise<WorkPackage> {
     if (await userHasPermission(user.userId, organization.organizationId, isGuest))
       throw new AccessDeniedGuestException('create work packages');
@@ -231,11 +218,8 @@ export default class WorkPackagesService {
         .map((element) => element.wbsElement.workPackageNumber)
         .reduce((prev, curr) => Math.max(prev, curr), 0) + 1;
 
-    // Normalize incoming startDate using user's local midnight converted to UTC when offset provided
-    const date = WorkPackagesService.toUtcMidnight(
-      startDate,
-      typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
-    );
+    // Parse the startDate to UTC midnight (frontend handles timezone formatting)
+    const date = WorkPackagesService.toUtcMidnight(startDate);
 
     const changesToCreate = crId
       ? [
@@ -335,8 +319,7 @@ export default class WorkPackagesService {
     descriptionBullets: DescriptionBulletPreview[],
     leadId: string | null,
     managerId: string | null,
-    organization: Organization,
-    clientOffsetMinutes?: number
+    organization: Organization
   ): Promise<WorkPackage> {
     const { userId } = user;
     // verify user is allowed to edit work packages
@@ -368,11 +351,8 @@ export default class WorkPackagesService {
 
     const blockedByElems = await validateBlockedBys(blockedBy, organization.organizationId);
 
-    // Normalize new startDate using user's local midnight converted to UTC when offset provided
-    const normalizedEdit = WorkPackagesService.toUtcMidnight(
-      startDate,
-      typeof clientOffsetMinutes === 'number' ? clientOffsetMinutes : undefined
-    );
+    // Parse new startDate to UTC midnight (frontend handles timezone formatting)
+    const normalizedEdit = WorkPackagesService.toUtcMidnight(startDate);
     const changes = await getWorkPackageChanges(
       originalWorkPackage.wbsElement.name,
       name,
diff --git a/src/frontend/package.json b/src/frontend/package.json
index bdf0864a26..501c1ab792 100644
--- a/src/frontend/package.json
+++ b/src/frontend/package.json
@@ -24,7 +24,7 @@
     "classnames": "^2.3.1",
     "customize-cra": "^1.0.0",
     "date-fns": "^4.1.0",
-    "dayjs": "^1.11.10",
+    "dayjs": "^1.11.18",
     "file-saver": "^2.0.5",
     "google-auth-library": "^9.15.0",
     "pdf-lib": "^1.17.1",
diff --git a/src/frontend/src/apis/work-packages.api.ts b/src/frontend/src/apis/work-packages.api.ts
index 1d5ed68441..02e164f099 100644
--- a/src/frontend/src/apis/work-packages.api.ts
+++ b/src/frontend/src/apis/work-packages.api.ts
@@ -17,8 +17,6 @@ export interface WorkPackageApiInputs {
   crId?: string;
   blockedBy: WbsNumber[];
   descriptionBullets: DescriptionBulletPreview[];
-  /** Optional client timezone offset in minutes (same sign as Date.getTimezoneOffset). */
-  clientOffsetMinutes?: number;
 }
 
 export interface WorkPackageCreateArgs extends WorkPackageApiInputs {
@@ -55,12 +53,7 @@ export const getSingleWorkPackage = (wbsNum: WbsNumber) => {
  * @param payload Payload containing all the necessary data to create a work package.
  */
 export const createSingleWorkPackage = (payload: WorkPackageCreateArgs) => {
-  const clientOffsetMinutes =
-    typeof payload.clientOffsetMinutes === 'number' ? payload.clientOffsetMinutes : new Date().getTimezoneOffset();
-  return axios.post<WorkPackage>(apiUrls.workPackagesCreate(), {
-    ...payload,
-    clientOffsetMinutes
-  });
+  return axios.post<WorkPackage>(apiUrls.workPackagesCreate(), payload);
 };
 
 /**
@@ -70,12 +63,7 @@ export const createSingleWorkPackage = (payload: WorkPackageCreateArgs) => {
  * @returns Promise that will resolve to either a success status code or a fail status code.
  */
 export const editWorkPackage = (payload: WorkPackageEditArgs) => {
-  const clientOffsetMinutes =
-    typeof payload.clientOffsetMinutes === 'number' ? payload.clientOffsetMinutes : new Date().getTimezoneOffset();
-  return axios.post<{ message: string }>(apiUrls.workPackagesEdit(), {
-    ...payload,
-    clientOffsetMinutes
-  });
+  return axios.post<{ message: string }>(apiUrls.workPackagesEdit(), payload);
 };
 
 /**
diff --git a/src/frontend/src/utils/datetime.utils.ts b/src/frontend/src/utils/datetime.utils.ts
index ea7c37442b..8eb7cd564a 100644
--- a/src/frontend/src/utils/datetime.utils.ts
+++ b/src/frontend/src/utils/datetime.utils.ts
@@ -19,10 +19,14 @@ export const dateFormatMonthDate = (date: Date) => {
   return dayjs(date).format('MMM D');
 };
 
+/**
+ * Transforms a Date object to a string in YYYY/MM/DD format using the user's local date
+ * This avoids timezone offset issues by using Day.js to format the date as-is
+ * @param date the Date object to transform
+ * @returns the date string in YYYY/MM/DD format
+ */
 export const transformDate = (date: Date) => {
-  const month = date.getMonth() + 1 < 10 ? `0${date.getMonth() + 1}` : (date.getMonth() + 1).toString();
-  const day = date.getDate() < 10 ? `0${date.getDate()}` : date.getDate().toString();
-  return `${date.getFullYear().toString()}/${month}/${day}`;
+  return dayjs(date).format('YYYY/MM/DD');
 };
 
 export const formatDate = (date: Date) => {
diff --git a/yarn.lock b/yarn.lock
index c93d2b252e..696a216a1a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -8537,13 +8537,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"dayjs@npm:^1.11.10":
-  version: 1.11.13
-  resolution: "dayjs@npm:1.11.13"
-  checksum: f388db88a6aa93956c1f6121644e783391c7b738b73dbc54485578736565c8931bdfba4bb94e9b1535c6e509c97d5deb918bbe1ae6b34358d994de735055cca9
-  languageName: node
-  linkType: hard
-
 "dayjs@npm:^1.11.18":
   version: 1.11.18
   resolution: "dayjs@npm:1.11.18"
@@ -10947,7 +10940,7 @@ __metadata:
     classnames: ^2.3.1
     customize-cra: ^1.0.0
     date-fns: ^4.1.0
-    dayjs: ^1.11.10
+    dayjs: ^1.11.18
     file-saver: ^2.0.5
     google-auth-library: ^9.15.0
     jest-fail-on-console: ^3.0.2

From 0b3b8aebf8f980a5d88e206d9b84c83569339785 Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Thu, 16 Oct 2025 20:11:52 -0400
Subject: [PATCH 10/16] prettier

---
 src/backend/src/services/work-packages.services.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index 499f95d812..dd408a6f6a 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -43,7 +43,7 @@ dayjs.extend(utc);
 export default class WorkPackagesService {
   /**
    * Normalize an input date string to the user's local midnight converted to UTC
-   * @param input - The date string to normalize 
+   * @param input - The date string to normalize
    * @returns date object representing midnight UTC
    */
   private static toUtcMidnight(input: string): Date {

From f2f77034f574a9c02807b5e299ab543a34eef484 Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Thu, 23 Oct 2025 17:29:03 -0400
Subject: [PATCH 11/16] syntax error

---
 src/backend/src/services/work-packages.services.ts | 4 ++--
 src/frontend/src/utils/datetime.utils.ts           | 7 +++----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index dd408a6f6a..b4a596e409 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -43,11 +43,11 @@ dayjs.extend(utc);
 export default class WorkPackagesService {
   /**
    * Normalize an input date string to the user's local midnight converted to UTC
-   * @param input - The date string to normalize
+   * @param input - The date string from the frontend
    * @returns date object representing midnight UTC
    */
   private static toUtcMidnight(input: string): Date {
-    return dayjs(input).utc().startOf('day').toDate();
+    return dayjs.utc(input).startOf('day').toDate();
   }
 
   /**
diff --git a/src/frontend/src/utils/datetime.utils.ts b/src/frontend/src/utils/datetime.utils.ts
index 8eb7cd564a..d0d1292967 100644
--- a/src/frontend/src/utils/datetime.utils.ts
+++ b/src/frontend/src/utils/datetime.utils.ts
@@ -20,13 +20,12 @@ export const dateFormatMonthDate = (date: Date) => {
 };
 
 /**
- * Transforms a Date object to a string in YYYY/MM/DD format using the user's local date
- * This avoids timezone offset issues by using Day.js to format the date as-is
+ * Transforms a Date object to a YYYY-MM-DD format using Day.js
  * @param date the Date object to transform
- * @returns the date string in YYYY/MM/DD format
+ * @returns the date string in YYYY-MM-DD format representing the user's calendar date
  */
 export const transformDate = (date: Date) => {
-  return dayjs(date).format('YYYY/MM/DD');
+  return dayjs(date).format('YYYY-MM-DD');
 };
 
 export const formatDate = (date: Date) => {

From 73dc4a7a70823efc0dc7e43333280e0cfc36d097 Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Wed, 5 Nov 2025 18:47:32 -0500
Subject: [PATCH 12/16] new date utils

---
 .../src/services/work-packages.services.ts    | 19 +++-------
 src/shared/src/date-utils.ts                  | 35 +++++++++++++++++++
 2 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index bc0f305d95..b62d86465d 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -13,7 +13,8 @@ import {
   WorkPackagePreview,
   WorkPackageStage,
   User,
-  WorkPackageSelection
+  WorkPackageSelection,
+  toUtcMidnight
 } from 'shared';
 import prisma from '../prisma/prisma';
 import {
@@ -29,8 +30,6 @@ import workPackageTransformer, { workPackagePreviewTransformer } from '../transf
 import { updateBlocking, validateChangeRequestAccepted } from '../utils/change-requests.utils';
 import { sendSlackUpcomingDeadlineNotification } from '../utils/slack.utils';
 import { getWorkPackageChanges } from '../utils/changes.utils';
-import dayjs from 'dayjs';
-import utc from 'dayjs/plugin/utc';
 import {
   DescriptionBulletDestination,
   addRawDescriptionBullets,
@@ -41,18 +40,8 @@ import { getDescriptionBulletQueryArgs } from '../prisma-query-args/description-
 import { userHasPermission } from '../utils/users.utils';
 import { getUserPreviewQueryArgs } from '../prisma-query-args/user.query-args';
 
-dayjs.extend(utc);
-
 /** Service layer containing logic for work package controller functions. */
 export default class WorkPackagesService {
-  /**
-   * Normalize an input date string to the user's local midnight converted to UTC
-   * @param input - The date string from the frontend
-   * @returns date object representing midnight UTC
-   */
-  private static toUtcMidnight(input: string): Date {
-    return dayjs.utc(input).startOf('day').toDate();
-  }
 
   /**
    * Retrieve all work packages, optionally filtered by query parameters.
@@ -222,7 +211,7 @@ export default class WorkPackagesService {
         .reduce((prev, curr) => Math.max(prev, curr), 0) + 1;
 
     // Parse the startDate to UTC midnight (frontend handles timezone formatting)
-    const date = WorkPackagesService.toUtcMidnight(startDate);
+    const date = toUtcMidnight(startDate);
 
     const changesToCreate = crId
       ? [
@@ -355,7 +344,7 @@ export default class WorkPackagesService {
     const blockedByElems = await validateBlockedBys(blockedBy, organization.organizationId);
 
     // Parse new startDate to UTC midnight (frontend handles timezone formatting)
-    const normalizedEdit = WorkPackagesService.toUtcMidnight(startDate);
+    const normalizedEdit = toUtcMidnight(startDate);
     const changes = await getWorkPackageChanges(
       originalWorkPackage.wbsElement.name,
       name,
diff --git a/src/shared/src/date-utils.ts b/src/shared/src/date-utils.ts
index a7980552c3..1f98184e1d 100644
--- a/src/shared/src/date-utils.ts
+++ b/src/shared/src/date-utils.ts
@@ -3,8 +3,43 @@
  * See the LICENSE file in the repository root folder for details.
  */
 
+import dayjs from 'dayjs';
+import utc from 'dayjs/plugin/utc';
 import { Availability } from './types/user-types';
 
+dayjs.extend(utc);
+
+/** 
+ * @returns Date object representing the user's local midnight converted to UTC
+ */
+export const toUtcMidnight = (input: string): Date => {
+  return dayjs(input).startOf('day').utc().toDate();
+};
+
+ /** 
+ * @param utcDate - The UTC date from the database
+ * @returns Date string in local timezone (YYYY-MM-DD format)
+ */
+export const fromUtcMidnight = (utcDate: Date): string => {
+  return dayjs.utc(utcDate).local().format('YYYY-MM-DD');
+};
+
+ /** 
+ * @returns Date object representing today at UTC midnight
+ */
+export const getCurrentUtcMidnight = (): Date => {
+  return dayjs().startOf('day').utc().toDate();
+};
+
+ /** 
+ * @param date1 - First date to compare
+ * @param date2 - Second date to compare
+ * @returns true if both dates represent the same calendar day
+ */
+export const isSameCalendarDay = (date1: Date, date2: Date): boolean => {
+  return dayjs(date1).format('YYYY-MM-DD') === dayjs(date2).format('YYYY-MM-DD');
+};
+
 /**
  * Add the given number of weeks to the given date and return the outcome.
  * @param start the start date

From c0a625dcb5ea5bde754cf5edd5a98358badbbb84 Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Thu, 20 Nov 2025 13:55:41 -0500
Subject: [PATCH 13/16] #1192 prettier

---
 src/backend/src/services/work-packages.services.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index b62d86465d..3bb8874f2e 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -42,7 +42,6 @@ import { getUserPreviewQueryArgs } from '../prisma-query-args/user.query-args';
 
 /** Service layer containing logic for work package controller functions. */
 export default class WorkPackagesService {
-
   /**
    * Retrieve all work packages, optionally filtered by query parameters.
    *

From bf2a3b31beebb144928218777875a0f3b1f64d5e Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Thu, 20 Nov 2025 13:57:15 -0500
Subject: [PATCH 14/16] #1192 prettier

---
 src/shared/src/date-utils.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/shared/src/date-utils.ts b/src/shared/src/date-utils.ts
index 1f98184e1d..1550d46a2a 100644
--- a/src/shared/src/date-utils.ts
+++ b/src/shared/src/date-utils.ts
@@ -9,14 +9,14 @@ import { Availability } from './types/user-types';
 
 dayjs.extend(utc);
 
-/** 
+/**
  * @returns Date object representing the user's local midnight converted to UTC
  */
 export const toUtcMidnight = (input: string): Date => {
   return dayjs(input).startOf('day').utc().toDate();
 };
 
- /** 
+/**
  * @param utcDate - The UTC date from the database
  * @returns Date string in local timezone (YYYY-MM-DD format)
  */
@@ -24,14 +24,14 @@ export const fromUtcMidnight = (utcDate: Date): string => {
   return dayjs.utc(utcDate).local().format('YYYY-MM-DD');
 };
 
- /** 
+/**
  * @returns Date object representing today at UTC midnight
  */
 export const getCurrentUtcMidnight = (): Date => {
   return dayjs().startOf('day').utc().toDate();
 };
 
- /** 
+/**
  * @param date1 - First date to compare
  * @param date2 - Second date to compare
  * @returns true if both dates represent the same calendar day

From c3829c642ff3105614f01328e032902e9e6627a5 Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Mon, 22 Dec 2025 13:25:44 -0500
Subject: [PATCH 15/16] #1192 applying date method in finance

---
 .../FinanceDashboard/AdminFinanceDashboard.tsx       |  6 +++---
 .../FinanceDashboard/GeneralFinanceDashboard.tsx     |  5 +++--
 src/shared/src/date-utils.ts                         | 12 ++++++++++++
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/frontend/src/pages/FinancePage/FinanceDashboard/AdminFinanceDashboard.tsx b/src/frontend/src/pages/FinancePage/FinanceDashboard/AdminFinanceDashboard.tsx
index 52fdce6039..180ba36f42 100644
--- a/src/frontend/src/pages/FinancePage/FinanceDashboard/AdminFinanceDashboard.tsx
+++ b/src/frontend/src/pages/FinancePage/FinanceDashboard/AdminFinanceDashboard.tsx
@@ -19,7 +19,7 @@ import TotalAmountSpentModal from '../FinanceComponents/TotalAmountSpentModal';
 import { DatePicker } from '@mui/x-date-pickers';
 import ListAltIcon from '@mui/icons-material/ListAlt';
 import WorkIcon from '@mui/icons-material/Work';
-import { isAdmin } from 'shared';
+import { isAdmin, dateToUtcMidnight } from 'shared';
 import { useGetAllCars } from '../../../hooks/cars.hooks';
 import NERAutocomplete from '../../../components/NERAutocomplete';
 
@@ -232,7 +232,7 @@ const AdminFinanceDashboard: React.FC<AdminFinanceDashboardProps> = ({ startDate
           },
           field: { clearable: true }
         }}
-        onChange={(newValue: Date | null) => setStartDateState(newValue ?? undefined)}
+        onChange={(newValue: Date | null) => setStartDateState(newValue ? dateToUtcMidnight(newValue) : undefined)}
       />
 
       <Box sx={{ display: 'flex', alignItems: 'center' }}>
@@ -251,7 +251,7 @@ const AdminFinanceDashboard: React.FC<AdminFinanceDashboardProps> = ({ startDate
           },
           field: { clearable: true }
         }}
-        onChange={(newValue: Date | null) => setEndDateState(newValue ?? undefined)}
+        onChange={(newValue: Date | null) => setEndDateState(newValue ? dateToUtcMidnight(newValue) : undefined)}
       />
       <Box sx={{ ml: 0 }}></Box>
       <NERButton
diff --git a/src/frontend/src/pages/FinancePage/FinanceDashboard/GeneralFinanceDashboard.tsx b/src/frontend/src/pages/FinancePage/FinanceDashboard/GeneralFinanceDashboard.tsx
index feb70ea017..0275bebb5a 100644
--- a/src/frontend/src/pages/FinancePage/FinanceDashboard/GeneralFinanceDashboard.tsx
+++ b/src/frontend/src/pages/FinancePage/FinanceDashboard/GeneralFinanceDashboard.tsx
@@ -10,6 +10,7 @@ import { useGetUsersTeams } from '../../../hooks/teams.hooks';
 import FinanceDashboardTeamView from './FinanceDashboardTeamView';
 import { useGetAllCars } from '../../../hooks/cars.hooks';
 import NERAutocomplete from '../../../components/NERAutocomplete';
+import { dateToUtcMidnight } from 'shared';
 
 interface GeneralFinanceDashboardProps {
   startDate?: Date;
@@ -156,7 +157,7 @@ const GeneralFinanceDashboard: React.FC<GeneralFinanceDashboardProps> = ({ start
           },
           field: { clearable: true }
         }}
-        onChange={(newValue: Date | null) => setStartDateState(newValue ?? undefined)}
+        onChange={(newValue: Date | null) => setStartDateState(newValue ? dateToUtcMidnight(newValue) : undefined)}
       />
 
       <Box sx={{ display: 'flex', alignItems: 'center' }}>
@@ -175,7 +176,7 @@ const GeneralFinanceDashboard: React.FC<GeneralFinanceDashboardProps> = ({ start
           },
           field: { clearable: true }
         }}
-        onChange={(newValue: Date | null) => setEndDateState(newValue ?? undefined)}
+        onChange={(newValue: Date | null) => setEndDateState(newValue ? dateToUtcMidnight(newValue) : undefined)}
       />
     </Box>
   );
diff --git a/src/shared/src/date-utils.ts b/src/shared/src/date-utils.ts
index 1550d46a2a..4352743723 100644
--- a/src/shared/src/date-utils.ts
+++ b/src/shared/src/date-utils.ts
@@ -16,6 +16,18 @@ export const toUtcMidnight = (input: string): Date => {
   return dayjs(input).startOf('day').utc().toDate();
 };
 
+/**
+ * Converts a Date object to UTC midnight, preserving the calendar day in the user's timezone
+ * @param date - The Date object from DatePicker (in user's local timezone)
+ * @returns Date object representing the selected day at UTC midnight
+ */
+export const dateToUtcMidnight = (date: Date): Date => {
+  const year = date.getFullYear();
+  const month = date.getMonth();
+  const day = date.getDate();
+  return dayjs.utc().year(year).month(month).date(day).startOf('day').toDate();
+};
+
 /**
  * @param utcDate - The UTC date from the database
  * @returns Date string in local timezone (YYYY-MM-DD format)

From b04d683f23ae5c5777bc7d516433ef21ff58db6f Mon Sep 17 00:00:00 2001
From: harish <harivarada1@gmail.com>
Date: Mon, 22 Dec 2025 14:37:49 -0500
Subject: [PATCH 16/16] #1192 prettier

---
 src/backend/src/services/work-packages.services.ts | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/backend/src/services/work-packages.services.ts b/src/backend/src/services/work-packages.services.ts
index 3bb8874f2e..3239eb7d01 100644
--- a/src/backend/src/services/work-packages.services.ts
+++ b/src/backend/src/services/work-packages.services.ts
@@ -209,7 +209,6 @@ export default class WorkPackagesService {
         .map((element) => element.wbsElement.workPackageNumber)
         .reduce((prev, curr) => Math.max(prev, curr), 0) + 1;
 
-    // Parse the startDate to UTC midnight (frontend handles timezone formatting)
     const date = toUtcMidnight(startDate);
 
     const changesToCreate = crId
@@ -342,7 +341,6 @@ export default class WorkPackagesService {
 
     const blockedByElems = await validateBlockedBys(blockedBy, organization.organizationId);
 
-    // Parse new startDate to UTC midnight (frontend handles timezone formatting)
     const normalizedEdit = toUtcMidnight(startDate);
     const changes = await getWorkPackageChanges(
       originalWorkPackage.wbsElement.name,