[MBL-19639][Student] Display lock date in device timezone instead of account timezone

Replace server-provided lockExplanation (formatted in account timezone) with
locally-formatted lock date using DateFormat to ensure consistency with other
dates on the assignment details screen.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hermannakos

apps/student/src/main/java/com/instructure/student/fragment/AssignmentBasicFragment.kt

@@ -17,6 +17,7 @@
 package com.instructure.student.fragment
 
 import android.os.Bundle
+import java.text.DateFormat
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -147,10 +148,13 @@ class AssignmentBasicFragment : ParentFragment() {
         // Assignment description can be null
         var description = when {
             assignment.isLocked -> getLockedInfoHTML(assignment.lockInfo!!, R.string.lockedAssignmentDesc)
-            assignment.lockDate?.before(Calendar.getInstance(Locale.getDefault()).time) == true ->
+            assignment.lockDate?.before(Calendar.getInstance(Locale.getDefault()).time) == true -> {
                 // If an assignment has an available from and until field and it has expired (the current date is after "until" it will have a lock explanation,
                 // but no lock info because it isn't Locked as part of a module
-                assignment.lockExplanation
+                val dateString = DateFormat.getDateInstance(DateFormat.LONG, Locale.getDefault()).format(assignment.lockDate!!)
+                val timeString = DateFormat.getTimeInstance(DateFormat.SHORT, Locale.getDefault()).format(assignment.lockDate!!)
+                getString(com.instructure.pandautils.R.string.closedSubtext, dateString, timeString)
+            }
             else -> assignment.description
         }
 

libs/pandautils/src/main/java/com/instructure/pandautils/features/assignments/details/AssignmentDetailsViewModel.kt

@@ -446,7 +446,11 @@ class AssignmentDetailsViewModel @Inject constructor(
             )
         }
 
-        val partialLockedMessage = assignment.lockExplanation.takeIf { it.isValid() && assignment.lockDate?.before(Date()).orDefault() }.orEmpty()
+        val partialLockedMessage = assignment.lockDate?.takeIf { it.before(Date()) }?.let {
+            val dateString = DateFormat.getDateInstance(DateFormat.LONG, Locale.getDefault()).format(it)
+            val timeString = DateFormat.getTimeInstance(DateFormat.SHORT, Locale.getDefault()).format(it)
+            resources.getString(R.string.closedSubtext, dateString, timeString)
+        }.orEmpty()
 
         val submissionHistory = assignment.submission?.submissionHistory
         val attempts = submissionHistory?.let { history ->

libs/pandautils/src/main/java/com/instructure/pandautils/utils/LocaleUtils.kt

@@ -30,6 +30,7 @@ import com.instructure.canvasapi2.utils.isValid
 import java.time.DayOfWeek
 import java.util.Calendar
 import java.util.Locale
+import java.util.TimeZone
 import kotlin.system.exitProcess
 
 object LocaleUtils {
@@ -66,6 +67,9 @@ object LocaleUtils {
             Locale.Builder().setLanguageTag(localeString).build()
         }
         Locale.setDefault(locale)
+        // Ensure device timezone is used for all date/time formatting
+        val deviceTimeZone = TimeZone.getDefault()
+        TimeZone.setDefault(deviceTimeZone)
         val config = Configuration()
         config.setLocales(LocaleList(locale))
         ContextKeeper.updateLocale(config)

libs/pandautils/src/main/res/values/strings.xml

@@ -171,6 +171,7 @@
     <string name="noSubmissionTeacher">This student doesn\'t have a submission yet.</string>
     <string name="locked">Locked</string>
     <string name="lockedSubtext">This assignment is locked until %1$s at %2$s.</string>
+    <string name="closedSubtext">This assignment was locked on %1$s at %2$s.</string>
     <string name="chooseFile">Choose a File</string>
     <string name="chooseFileSubtext">Attach a file to your submission by tapping an option below.</string>
     <string name="chooseFileForUploadSubtext">Select a file to upload by tapping an option below</string>

libs/pandautils/src/test/java/com/instructure/pandautils/features/assignments/details/AssignmentDetailsViewModelTest.kt

@@ -77,6 +77,7 @@ import org.junit.Rule
 import org.junit.Test
 import java.util.Calendar
 import java.util.Date
+import java.util.Locale
 
 @ExperimentalCoroutinesApi
 class AssignmentDetailsViewModelTest {
@@ -188,24 +189,27 @@ class AssignmentDetailsViewModelTest {
 
     @Test
     fun `Load partially locked assignment`() {
-        val lockedExplanation = "locked"
+        val lockDate = Calendar.getInstance().apply { add(Calendar.DAY_OF_MONTH, -1) }.time
+        val dateString = java.text.DateFormat.getDateInstance(java.text.DateFormat.LONG, Locale.getDefault()).format(lockDate)
+        val timeString = java.text.DateFormat.getTimeInstance(java.text.DateFormat.SHORT, Locale.getDefault()).format(lockDate)
+        val expectedLockedMessage = "This assignment was locked on $dateString at $timeString."
 
-        every { resources.getString(R.string.errorLoadingAssignment) } returns lockedExplanation
+        every { resources.getString(R.string.errorLoadingAssignment) } returns ""
+        every { resources.getString(R.string.closedSubtext, dateString, timeString) } returns expectedLockedMessage
 
         val course = Course(enrollments = mutableListOf(Enrollment(type = Enrollment.EnrollmentType.Student)))
         coEvery { assignmentDetailsRepository.getCourseWithGrade(any(), any()) } returns course
 
         val assignment = Assignment(
-            lockExplanation = lockedExplanation,
-            lockAt = Calendar.getInstance().apply { add(Calendar.DAY_OF_MONTH, -1) }.time.toApiString()
+            lockAt = lockDate.toApiString()
         )
         coEvery { assignmentDetailsRepository.getAssignment(any(), any(), any(), any()) } returns assignment
 
         val viewModel = getViewModel()
 
         assertEquals(ViewState.Success, viewModel.state.value)
         assertEquals(false, viewModel.data.value?.fullLocked)
-        assertEquals(lockedExplanation, viewModel.data.value?.lockedMessage)
+        assertEquals(expectedLockedMessage, viewModel.data.value?.lockedMessage)
     }
 
     @Test