feat: persistance de l'historique des parties en JSON (okio)

sharedUI/src/commonMain/kotlin/com/livrets/data/HistoryRepository.kt

@@ -0,0 +1,32 @@
+package com.livrets.data
+
+import com.livrets.game.GameResult
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import kotlinx.serialization.builtins.ListSerializer
+import kotlinx.serialization.json.Json
+import okio.FileSystem
+import okio.Path
+
+class HistoryRepository(
+    private val filePath: Path,
+    private val fileSystem: FileSystem = FileSystem.SYSTEM,
+) {
+    private val json = Json { ignoreUnknownKeys = true }
+
+    suspend fun load(): List<GameResult> = withContext(Dispatchers.IO) {
+        if (!fileSystem.exists(filePath)) return@withContext emptyList()
+        fileSystem.read(filePath) { readUtf8() }
+            .let { json.decodeFromString(ListSerializer(GameResult.serializer()), it) }
+    }
+
+    suspend fun save(result: GameResult) {
+        val all = load() + result
+        withContext(Dispatchers.IO) {
+            filePath.parent?.let { fileSystem.createDirectories(it) }
+            fileSystem.write(filePath) {
+                writeUtf8(json.encodeToString(ListSerializer(GameResult.serializer()), all))
+            }
+        }
+    }
+}

sharedUI/src/commonTest/kotlin/com/livrets/data/HistoryRepositoryTest.kt

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+package com.livrets.data
+
+import com.livrets.game.AnswerRecord
+import com.livrets.game.GameConfig
+import com.livrets.game.GameResult
+import com.livrets.game.Question
+import kotlinx.coroutines.test.runTest
+import kotlin.time.Instant
+import okio.fakefilesystem.FakeFileSystem
+import okio.Path.Companion.toPath
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class HistoryRepositoryTest {
+
+    private fun gameResult(date: String, score: Int) = GameResult(
+        date = Instant.parse(date),
+        config = GameConfig(10, 10, 12),
+        records = List(score) {
+            AnswerRecord(Question.Direct(2, 3), 6, 6, true, 900L)
+        } + List(10 - score) {
+            AnswerRecord(Question.Direct(2, 3), null, 6, false, 10_000L)
+        },
+    )
+
+    @Test
+    fun `chargement vide quand aucun fichier`() = runTest {
+        val fs = FakeFileSystem()
+        val repo = HistoryRepository("/docs/history.json".toPath(), fs)
+        assertTrue(repo.load().isEmpty())
+    }
+
+    @Test
+    fun `aller-retour sauvegarde puis chargement`() = runTest {
+        val fs = FakeFileSystem()
+        val repo = HistoryRepository("/docs/history.json".toPath(), fs)
+        val first = gameResult("2026-01-01T00:00:00Z", score = 7)
+        val second = gameResult("2026-02-02T00:00:00Z", score = 4)
+
+        repo.save(first)
+        assertEquals(listOf(first), repo.load())
+
+        repo.save(second)
+        assertEquals(listOf(first, second), repo.load())
+        assertTrue(fs.exists("/docs/history.json".toPath()))
+    }
+}