fix(worldclock): leave a fitting margin and drop the zone-cache reset

The fitted seconds size keeps five percent spare, since hinted glyph
advances do not scale exactly. The receiver no longer resets the
process's default zone: that was speculative, and it changed global
state from a UI flow. The settings state takes the seconds flag without
a default, and a garbled KDoc sentence is fixed.

app/src/main/java/de/jeanlucmakiola/clockula/data/time/AndroidClockChanges.kt

@@ -10,7 +10,6 @@ import de.jeanlucmakiola.clockula.domain.time.ClockChanges
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
-import java.util.TimeZone
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -28,11 +27,6 @@ class AndroidClockChanges @Inject constructor(
     override fun changes(): Flow<Unit> = callbackFlow {
         val receiver = object : BroadcastReceiver() {
             override fun onReceive(context: Context, intent: Intent) {
-                // The process's cached default zone is reset by a separate
-                // one-way call that can land after this broadcast; resetting it
-                // here too (as ActivityThread does) means the rebuild this
-                // triggers reads the new zone, not the old one.
-                if (intent.action == Intent.ACTION_TIMEZONE_CHANGED) TimeZone.setDefault(null)
                 trySend(Unit)
             }
         }

app/src/main/java/de/jeanlucmakiola/clockula/ui/settings/SettingsUiState.kt

@@ -15,7 +15,7 @@ internal sealed interface SettingsUiState {
         val defaults: ClockDefaults,
         val selfCheckProblemCount: Int? = null,
         /** The world clock's "Display time with seconds" (#23); not a clock default. */
-        val worldClockSeconds: Boolean = false,
+        val worldClockSeconds: Boolean,
     ) : SettingsUiState
 }
 

app/src/main/java/de/jeanlucmakiola/clockula/ui/worldclock/WorldClockRow.kt

@@ -175,6 +175,8 @@ internal data class RowTimeStyle(val style: TextStyle, val maxWidth: Dp) {
     val capped: Boolean get() = maxWidth != Dp.Infinity
 }
 
+private const val FitMargin = 0.95f
+
 /** Wide enough for "12:59:59 PM" at the default scale; the city keeps the rest. */
 private val SecondsMaxWidth = 168.dp
 
@@ -209,7 +211,8 @@ internal fun rememberRowTimeStyle(showSeconds: Boolean, formatTime: (LocalTime)
         val fitted = if (width <= cap) {
             style
         } else {
-            style.copy(fontSize = with(density) { (style.fontSize.toPx() * cap / width).toSp() })
+            // A few percent spare: hinted glyph advances do not scale exactly.
+            style.copy(fontSize = with(density) { (style.fontSize.toPx() * FitMargin * cap / width).toSp() })
         }
         RowTimeStyle(fitted, SecondsMaxWidth)
     }

app/src/main/java/de/jeanlucmakiola/clockula/ui/worldclock/WorldClockSource.kt

@@ -45,8 +45,9 @@ internal class WorldClockSource @Inject constructor(
     /**
      * The tab's state. Both the instant and the device zone are re-read on
      * **every tick**. [ClockChanges] restarts the tick, so `TIME_SET` and
-     * `TIMEZONE_CHANGED` show at once rather than at the next minute, the next
-     * wait is measured against the clock as it now reads. It sits
+     * `TIMEZONE_CHANGED` show at once rather than at the next minute, and the
+     * restarted ticker measures its next wait against the clock as it now
+     * reads. It sits
      * outside the `flatMapLatest`, so its receiver is registered once per
      * subscription rather than once per list edit, and `onStart` lets the
      * first state through without waiting for a broadcast. [refreshes] does

docs/ARCHITECTURE.md

@@ -2464,9 +2464,7 @@ arrive with the tab on screen (a network zone change on landing, split
 screen). So `ClockChanges` (`AndroidClockChanges`, a receiver registered only
 while the tab collects) restarts the tick: those two make the state re-read
 the clock and the zone at once, and the restarted ticker measures its next
-wait against the clock as it now reads. On `TIMEZONE_CHANGED` the receiver
-also resets the process's cached default zone itself, since the system's own
-reset is a separate call that can land after the broadcast. The signal is combined
+wait against the clock as it now reads. The signal is combined
 with the stored list, the home zone and the setting *outside* the
 `flatMapLatest`, so the receiver is registered once per subscription, not
 once per list edit. Each broadcast costs one extra `build`, which