refactor(timeago): consolidate toggle into one stable composable

Audit follow-up — the toggle behaviour now lives in a single
`ToggleableTimeAgoText` core in `ui/note/elements/TimeAgo.kt`. `TimeAgo`,
`NormalTimeAgo`, `ChatTimeAgo`, and `ChatroomHeaderCompose.TimeAgo` are
thin wrappers that pick a `TimeAgoStyle` (Dotted / Short) and pass
colour/font params; no per-site duplication of state + clickable +
derivedStateOf.

Performance fixes that matter for a feed with hundreds of timestamps:

- `rememberSaveable` → `remember`. Persisting a transient peek-toggle to
  the SavedStateRegistry for every visible+scrolled-past note was pure
  memory bloat. Recycling now resets to relative, which is the expected
  behaviour for a transient inspect action.
- The relative-mode `derivedStateOf` lambda reads `nowState.value` only
  when displaying a relative time. An item the user has frozen to its
  absolute date no longer re-evaluates every 30-second tick.
- Core composable takes only stable primitive params (Long, Color,
  TextUnit, TextOverflow, enum) so Compose can skip it entirely when
  inputs don't change.
- Desktop wrapper dropped the redundant `derivedStateOf`: its formatter
  reads no State, so derivedStateOf had nothing to observe.

https://claude.ai/code/session_01AuPon9VQeRfKV1BTVQuKGC

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/elements/TimeAgo.kt

@@ -22,6 +22,7 @@ package com.vitorpamplona.amethyst.ui.note.elements
 
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.interaction.MutableInteractionSource
+import androidx.compose.material3.LocalContentColor
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
@@ -29,11 +30,12 @@ import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.TextUnit
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.model.Note
 import com.vitorpamplona.amethyst.ui.note.timeAbsolute
@@ -43,6 +45,85 @@ import com.vitorpamplona.amethyst.ui.note.timeAgoShort
 import com.vitorpamplona.amethyst.ui.stringRes
 import com.vitorpamplona.amethyst.ui.theme.placeholderText
 
+/**
+ * Which relative-time format to use when the timestamp is *not* toggled to absolute.
+ * Absolute-mode uses [timeAbsolute] (dotted) or [timeAbsoluteNoDot] regardless.
+ */
+enum class TimeAgoStyle {
+    /** "• 5m", uses [timeAgo]. Used by note timestamps and chatroom row last-message time. */
+    Dotted,
+
+    /** "5m" (no dot, no leading space), uses [timeAgoShort]. Used by chat bubbles and channel headers. */
+    Short,
+}
+
+/**
+ * Core toggleable timestamp Text. All on-screen TimeAgo composables delegate to this.
+ *
+ * Behaviour:
+ * - Renders the timestamp relative to "now" (subscribing to [LocalNowSeconds]); on click,
+ *   flips to an absolute date/time formatted by [timeAbsolute] / [timeAbsoluteNoDot].
+ * - When displaying the absolute form we **stop subscribing to the tick** — the
+ *   `derivedStateOf` lambda doesn't read `nowState.value` in that branch, so the Text
+ *   does not recompose every 30s for items the user has "frozen" to a specific time.
+ * - Uses [remember] (not `rememberSaveable`): the toggle is a transient peek, not state
+ *   worth saving to the SavedStateRegistry for every visible+scrolled-past note in the
+ *   feed. Recycling resets to relative, which matches how peeking should work.
+ * - A single [MutableInteractionSource] per item, no ripple — tiny timestamp Text
+ *   doesn't benefit from the indication.
+ *
+ * Stable params: all values, so the Compose compiler can skip this entirely when nothing changes.
+ */
+@Composable
+fun ToggleableTimeAgoText(
+    timestamp: Long,
+    modifier: Modifier = Modifier,
+    style: TimeAgoStyle = TimeAgoStyle.Dotted,
+    color: Color = LocalContentColor.current,
+    fontSize: TextUnit = TextUnit.Unspecified,
+    maxLines: Int = 1,
+    overflow: TextOverflow = TextOverflow.Clip,
+) {
+    val context = LocalContext.current
+    val nowState = LocalNowSeconds.current
+    val nowStr = stringRes(id = R.string.now)
+    val interactionSource = remember { MutableInteractionSource() }
+    var showAbsolute by remember(timestamp) { mutableStateOf(false) }
+
+    val text by
+        remember(timestamp, context, style, nowState, nowStr) {
+            derivedStateOf {
+                if (showAbsolute) {
+                    when (style) {
+                        TimeAgoStyle.Dotted -> timeAbsolute(timestamp, context)
+                        TimeAgoStyle.Short -> timeAbsoluteNoDot(timestamp, context)
+                    }
+                } else {
+                    // Read nowState only when displaying a relative time, so an item
+                    // toggled to absolute doesn't recompose on every 30-second tick.
+                    nowState.value
+                    when (style) {
+                        TimeAgoStyle.Dotted -> timeAgo(timestamp, context)
+                        TimeAgoStyle.Short -> timeAgoShort(timestamp, nowStr)
+                    }
+                }
+            }
+        }
+
+    Text(
+        text = text,
+        color = color,
+        fontSize = fontSize,
+        maxLines = maxLines,
+        overflow = overflow,
+        modifier =
+            modifier.clickable(
+                interactionSource = interactionSource,
+                indication = null,
+            ) { showAbsolute = !showAbsolute },
+    )
+}
+
 @Composable
 fun TimeAgo(note: Note) {
     val time = note.createdAt() ?: return
@@ -51,30 +132,10 @@ fun TimeAgo(note: Note) {
 
 @Composable
 fun TimeAgo(time: Long) {
-    val context = LocalContext.current
-    // Subscribe to the shared coarse ticker; `derivedStateOf` ensures the Text only
-    // recomposes when the formatted string actually flips (e.g. 1m → 2m), not on every tick.
-    val nowState = LocalNowSeconds.current
-    var showAbsolute by rememberSaveable(time) { mutableStateOf(false) }
-    val interactionSource = remember { MutableInteractionSource() }
-
-    val timeStr by
-        remember(time, context, nowState) {
-            derivedStateOf {
-                nowState.value
-                if (showAbsolute) timeAbsolute(time, context) else timeAgo(time, context = context)
-            }
-        }
-
-    Text(
-        text = timeStr,
+    ToggleableTimeAgoText(
+        timestamp = time,
+        style = TimeAgoStyle.Dotted,
         color = MaterialTheme.colorScheme.placeholderText,
-        maxLines = 1,
-        modifier =
-            Modifier.clickable(
-                interactionSource = interactionSource,
-                indication = null,
-            ) { showAbsolute = !showAbsolute },
     )
 }
 
@@ -83,29 +144,11 @@ fun NormalTimeAgo(
     baseNote: Note,
     modifier: Modifier,
 ) {
-    val nowStr = stringRes(id = R.string.now)
-    val nowState = LocalNowSeconds.current
-    val context = LocalContext.current
-    var showAbsolute by rememberSaveable(baseNote.idHex) { mutableStateOf(false) }
-    val interactionSource = remember { MutableInteractionSource() }
-
-    val time by
-        remember(baseNote, nowStr, nowState) {
-            derivedStateOf {
-                nowState.value
-                val createdAt = baseNote.createdAt() ?: 0L
-                if (showAbsolute) timeAbsoluteNoDot(createdAt, context) else timeAgoShort(createdAt, nowStr)
-            }
-        }
-
-    Text(
-        text = time,
-        maxLines = 1,
+    val time = baseNote.createdAt() ?: 0L
+    ToggleableTimeAgoText(
+        timestamp = time,
+        style = TimeAgoStyle.Short,
         overflow = TextOverflow.Ellipsis,
-        modifier =
-            modifier.clickable(
-                interactionSource = interactionSource,
-                indication = null,
-            ) { showAbsolute = !showAbsolute },
+        modifier = modifier,
     )
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/feed/ChatTimeAgo.kt

@@ -20,20 +20,13 @@
  */
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed
 
-import androidx.compose.foundation.clickable
-import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.size
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.derivedStateOf
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.saveable.rememberSaveable
-import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
@@ -42,9 +35,8 @@ import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.commons.icons.symbols.Icon
 import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
 import com.vitorpamplona.amethyst.model.Note
-import com.vitorpamplona.amethyst.ui.note.elements.LocalNowSeconds
-import com.vitorpamplona.amethyst.ui.note.timeAbsoluteNoDot
-import com.vitorpamplona.amethyst.ui.note.timeAgoShort
+import com.vitorpamplona.amethyst.ui.note.elements.TimeAgoStyle
+import com.vitorpamplona.amethyst.ui.note.elements.ToggleableTimeAgoText
 import com.vitorpamplona.amethyst.ui.note.timeAheadNoDot
 import com.vitorpamplona.amethyst.ui.stringRes
 import com.vitorpamplona.amethyst.ui.theme.Font12SP
@@ -54,31 +46,11 @@ import com.vitorpamplona.quartz.nip40Expiration.expiration
 
 @Composable
 fun ChatTimeAgo(baseNote: Note) {
-    val nowStr = stringRes(id = R.string.now)
-    val nowState = LocalNowSeconds.current
-    val context = LocalContext.current
-    var showAbsolute by rememberSaveable(baseNote.idHex) { mutableStateOf(false) }
-    val interactionSource = remember { MutableInteractionSource() }
-
-    val time by
-        remember(baseNote, nowStr, nowState) {
-            derivedStateOf {
-                nowState.value
-                val createdAt = baseNote.createdAt() ?: 0L
-                if (showAbsolute) timeAbsoluteNoDot(createdAt, context) else timeAgoShort(createdAt, nowStr)
-            }
-        }
-
-    Text(
-        text = time,
+    ToggleableTimeAgoText(
+        timestamp = baseNote.createdAt() ?: 0L,
+        style = TimeAgoStyle.Short,
         color = MaterialTheme.colorScheme.placeholderText,
         fontSize = Font12SP,
-        maxLines = 1,
-        modifier =
-            Modifier.clickable(
-                interactionSource = interactionSource,
-                indication = null,
-            ) { showAbsolute = !showAbsolute },
     )
 }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/rooms/ChatroomHeaderCompose.kt

@@ -20,8 +20,6 @@
  */
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms
 
-import androidx.compose.foundation.clickable
-import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.material3.LocalTextStyle
@@ -29,14 +27,11 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.SpanStyle
 import androidx.compose.ui.text.buildAnnotatedString
 import androidx.compose.ui.text.font.FontWeight
@@ -64,9 +59,8 @@ import com.vitorpamplona.amethyst.ui.note.LoadDecryptedContentOrNull
 import com.vitorpamplona.amethyst.ui.note.LoadPublicChatChannel
 import com.vitorpamplona.amethyst.ui.note.NonClickableUserPictures
 import com.vitorpamplona.amethyst.ui.note.ObserveDraftEvent
-import com.vitorpamplona.amethyst.ui.note.elements.LocalNowSeconds
-import com.vitorpamplona.amethyst.ui.note.timeAbsolute
-import com.vitorpamplona.amethyst.ui.note.timeAgo
+import com.vitorpamplona.amethyst.ui.note.elements.TimeAgoStyle
+import com.vitorpamplona.amethyst.ui.note.elements.ToggleableTimeAgoText
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.privateDM.header.RoomNameDisplay
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.ephemChat.LoadEphemeralChatChannel
@@ -487,27 +481,10 @@ fun ChannelName(
 @Composable
 private fun TimeAgo(channelLastTime: Long?) {
     if (channelLastTime == null) return
-
-    val context = LocalContext.current
-    val nowState = LocalNowSeconds.current
-    var showAbsolute by rememberSaveable(channelLastTime) { mutableStateOf(false) }
-    val interactionSource = remember { MutableInteractionSource() }
-    val timeAgo by
-        remember(channelLastTime, context, nowState) {
-            derivedStateOf {
-                nowState.value
-                if (showAbsolute) timeAbsolute(channelLastTime, context) else timeAgo(channelLastTime, context)
-            }
-        }
-    Text(
-        text = timeAgo,
+    ToggleableTimeAgoText(
+        timestamp = channelLastTime,
+        style = TimeAgoStyle.Dotted,
         color = MaterialTheme.colorScheme.grayText,
-        maxLines = 1,
-        modifier =
-            Modifier.clickable(
-                interactionSource = interactionSource,
-                indication = null,
-            ) { showAbsolute = !showAbsolute },
     )
 }