feat(chat): open date separators after a one-hour pause

apps/flipcash/shared/chat-ui/src/main/kotlin/com/flipcash/shared/chat/models/SeparatorConfig.kt

@@ -29,7 +29,7 @@ sealed interface SeparatorConfig {
     }
 
     data class Continuous(
-        val gap: Duration = 3.hours,
+        val gap: Duration = 1.hours,
     ) : SeparatorConfig {
         override val groupingWindow: Duration = Duration.INFINITE
         override fun shouldSeparate(before: Instant, after: Instant): Boolean =

apps/flipcash/shared/chat-ui/src/test/kotlin/com/flipcash/shared/chat/models/SeparatorConfigTest.kt

@@ -0,0 +1,48 @@
+package com.flipcash.shared.chat.models
+
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.atTime
+import kotlinx.datetime.toInstant
+import org.junit.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+import kotlin.time.Duration.Companion.hours
+import kotlin.time.Duration.Companion.minutes
+
+/** The transcript opens a date separator after a one-hour pause, or at a change of day. */
+class SeparatorConfigTest {
+
+    // Local noon keeps the offsets below on the same calendar day in any time zone.
+    private val noon = LocalDate(2024, 1, 10)
+        .atTime(12, 0)
+        .toInstant(TimeZone.currentSystemDefault())
+
+    private val config = SeparatorConfig.Continuous()
+
+    @Test
+    fun `default gap is one hour`() {
+        assertEquals(1.hours, config.gap)
+    }
+
+    @Test
+    fun `separates after a 90 minute pause on the same day`() {
+        assertTrue(config.shouldSeparate(noon, noon + 90.minutes))
+    }
+
+    @Test
+    fun `separates regardless of argument order`() {
+        assertTrue(config.shouldSeparate(noon + 90.minutes, noon))
+    }
+
+    @Test
+    fun `does not separate after a 30 minute pause on the same day`() {
+        assertFalse(config.shouldSeparate(noon, noon + 30.minutes))
+    }
+
+    @Test
+    fun `does not separate at exactly one hour`() {
+        assertFalse(config.shouldSeparate(noon, noon + 1.hours))
+    }
+}