Fix review findings in the date subheaders

- Key each date header by its label instead of the group's first comment id, so
  a header stays stable (no remove+add re-animation) when a newer comment is
  prepended into an existing date group. Labels are unique per contiguous group
  given the date sort. Drops the now-unneeded keyId field.
- Uppercase the header label with the default locale, matching the legacy
  subheader's locale-aware textAllCaps (Kotlin's no-arg uppercase() is
  Locale.ROOT and mis-cases e.g. Turkish month names).

Author: nbradbury

WordPress/src/main/java/org/wordpress/android/ui/commentsrs/CommentsRsListRow.kt

@@ -2,8 +2,7 @@ package org.wordpress.android.ui.commentsrs
 
 /** A rendered row in the rs comment list: either a date-group header or a comment. */
 sealed interface CommentsRsListRow {
-    /** A date subheader. [keyId] is the first comment id in the group, for a stable LazyColumn key. */
-    data class DateHeader(val label: String, val keyId: Long) : CommentsRsListRow
+    data class DateHeader(val label: String) : CommentsRsListRow
     data class Item(val comment: CommentRsUiModel) : CommentsRsListRow
 }
 
@@ -12,13 +11,17 @@ sealed interface CommentsRsListRow {
  * list: a header before the first comment and before every comment whose date label differs from
  * the previous one. The label is the row's own [CommentRsUiModel.relativeDate] — the same
  * javaDateToTimeSpan value the legacy list groups by — so no extra date handling is needed here.
+ *
+ * The label doubles as the header's LazyColumn key: comments are date-sorted, so a label maps to
+ * exactly one contiguous group (unique key), and keying by the label rather than the group's first
+ * comment keeps the header stable when a newer comment is prepended into an existing group.
  */
 fun withDateHeaders(comments: List<CommentRsUiModel>): List<CommentsRsListRow> {
     val rows = ArrayList<CommentsRsListRow>(comments.size + 1)
     var lastLabel: String? = null
     for (comment in comments) {
         if (comment.relativeDate != lastLabel) {
-            rows.add(CommentsRsListRow.DateHeader(comment.relativeDate, comment.remoteCommentId))
+            rows.add(CommentsRsListRow.DateHeader(comment.relativeDate))
             lastLabel = comment.relativeDate
         }
         rows.add(CommentsRsListRow.Item(comment))

WordPress/src/main/java/org/wordpress/android/ui/commentsrs/screens/CommentsRsListItem.kt

@@ -39,6 +39,7 @@ import androidx.compose.ui.unit.dp
 import coil.compose.AsyncImage
 import org.wordpress.android.R
 import org.wordpress.android.ui.commentsrs.CommentRsUiModel
+import java.util.Locale
 
 private val AVATAR_SIZE = 40.dp
 private val PENDING_INDICATOR_WIDTH = 4.dp
@@ -178,7 +179,9 @@ private fun AnnotatedString.Builder.boldRange(formatted: String, part: String) {
 @Composable
 fun CommentsRsDateHeader(label: String, modifier: Modifier = Modifier) {
     Text(
-        text = label.uppercase(),
+        // Locale-aware uppercase, like the legacy subheader's android:textAllCaps (Kotlin's no-arg
+        // uppercase() is Locale.ROOT and would mis-case e.g. Turkish month names).
+        text = label.uppercase(Locale.getDefault()),
         style = MaterialTheme.typography.labelMedium,
         color = MaterialTheme.colorScheme.onSurfaceVariant,
         maxLines = 1,

WordPress/src/main/java/org/wordpress/android/ui/commentsrs/screens/CommentsRsTabListScreen.kt

@@ -148,7 +148,7 @@ private fun CommentListContent(
             items = rows,
             key = { row ->
                 when (row) {
-                    is CommentsRsListRow.DateHeader -> "header_${row.keyId}"
+                    is CommentsRsListRow.DateHeader -> "header_${row.label}"
                     is CommentsRsListRow.Item -> row.comment.remoteCommentId
                 }
             },

WordPress/src/test/java/org/wordpress/android/ui/commentsrs/CommentsRsListRowTest.kt

@@ -17,7 +17,7 @@ class CommentsRsListRowTest {
         val comment = comment(id = 1, date = "Today")
 
         assertThat(withDateHeaders(listOf(comment))).containsExactly(
-            DateHeader("Today", keyId = 1),
+            DateHeader("Today"),
             Item(comment)
         )
     }
@@ -28,7 +28,7 @@ class CommentsRsListRowTest {
         val b = comment(id = 2, date = "Today")
 
         assertThat(withDateHeaders(listOf(a, b))).containsExactly(
-            DateHeader("Today", keyId = 1),
+            DateHeader("Today"),
             Item(a),
             Item(b)
         )
@@ -42,26 +42,26 @@ class CommentsRsListRowTest {
         val d = comment(id = 4, date = "January 8")
 
         assertThat(withDateHeaders(listOf(a, b, c, d))).containsExactly(
-            DateHeader("Today", keyId = 1),
+            DateHeader("Today"),
             Item(a),
             Item(b),
-            DateHeader("Yesterday", keyId = 3),
+            DateHeader("Yesterday"),
             Item(c),
-            DateHeader("January 8", keyId = 4),
+            DateHeader("January 8"),
             Item(d)
         )
     }
 
     @Test
-    fun `each header is keyed by the first comment in its group`() {
-        val rows = withDateHeaders(
-            listOf(
-                comment(id = 10, date = "Today"),
-                comment(id = 11, date = "Yesterday")
-            )
-        )
+    fun `a header stays identical when a newer comment is prepended into its group`() {
+        // The header is keyed by its label, so adding a same-day comment at the top of the group
+        // must not change the header's identity (which would make it re-animate on refresh).
+        val before = withDateHeaders(listOf(comment(id = 1, date = "Today")))
+        val after = withDateHeaders(listOf(comment(id = 2, date = "Today"), comment(id = 1, date = "Today")))
 
-        assertThat(rows.filterIsInstance<DateHeader>().map { it.keyId }).containsExactly(10, 11)
+        val beforeHeader = before.filterIsInstance<DateHeader>().single()
+        val afterHeader = after.filterIsInstance<DateHeader>().single()
+        assertThat(afterHeader).isEqualTo(beforeHeader)
     }
 
     private fun comment(id: Long, date: String) = CommentRsUiModel(