From 7efad77fdea5b73845a7b2198b088ff5effc0eb9 Mon Sep 17 00:00:00 2001
From: Jean-Luc Makiola <business@jeanlucmakiola.de>
Date: Sat, 27 Jun 2026 23:37:25 +0200
Subject: [PATCH] core-time: add TimeBridge (Instant <-> epoch millis)

Generic content-provider time bridge shared by the family: Long epoch millis
<-> kotlin.time.Instant. Extracted from Calendula for Phase 1 (Calendula as the
second core-time consumer). 3 unit tests; module suite now 5 green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .../jeanlucmakiola/floret/time/TimeBridge.kt  |  9 +++++++
 .../floret/time/TimeBridgeTest.kt             | 26 +++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 core-time/src/main/kotlin/de/jeanlucmakiola/floret/time/TimeBridge.kt
 create mode 100644 core-time/src/test/kotlin/de/jeanlucmakiola/floret/time/TimeBridgeTest.kt

diff --git a/core-time/src/main/kotlin/de/jeanlucmakiola/floret/time/TimeBridge.kt b/core-time/src/main/kotlin/de/jeanlucmakiola/floret/time/TimeBridge.kt
new file mode 100644
index 0000000..c9b193d
--- /dev/null
+++ b/core-time/src/main/kotlin/de/jeanlucmakiola/floret/time/TimeBridge.kt
@@ -0,0 +1,9 @@
+package de.jeanlucmakiola.floret.time
+
+import kotlin.time.Instant
+
+/** Epoch milliseconds (as stored by Android content providers) → [Instant]. */
+fun Long.toKotlinInstantFromEpochMillis(): Instant = Instant.fromEpochMilliseconds(this)
+
+/** [Instant] → epoch milliseconds, for writing back to a content provider. */
+fun Instant.toEpochMillis(): Long = toEpochMilliseconds()
diff --git a/core-time/src/test/kotlin/de/jeanlucmakiola/floret/time/TimeBridgeTest.kt b/core-time/src/test/kotlin/de/jeanlucmakiola/floret/time/TimeBridgeTest.kt
new file mode 100644
index 0000000..a7f26b2
--- /dev/null
+++ b/core-time/src/test/kotlin/de/jeanlucmakiola/floret/time/TimeBridgeTest.kt
@@ -0,0 +1,26 @@
+package de.jeanlucmakiola.floret.time
+
+import com.google.common.truth.Truth.assertThat
+import kotlin.time.Instant
+import org.junit.jupiter.api.Test
+
+class TimeBridgeTest {
+
+    @Test
+    fun `epoch millis round-trips through Instant`() {
+        val original = 1_717_840_800_000L // 2024-06-08T10:00:00Z
+        val instant = original.toKotlinInstantFromEpochMillis()
+        assertThat(instant.toEpochMillis()).isEqualTo(original)
+    }
+
+    @Test
+    fun `zero millis maps to Instant epoch`() {
+        assertThat(0L.toKotlinInstantFromEpochMillis()).isEqualTo(Instant.fromEpochMilliseconds(0L))
+    }
+
+    @Test
+    fun `negative epoch millis is supported`() {
+        val original = -1_000_000L
+        assertThat(original.toKotlinInstantFromEpochMillis().toEpochMillis()).isEqualTo(original)
+    }
+}