Add count methods to JournalStore API and implementations for message counting per conversation (count(conversationId) and count(conversationId, after)), with supporting tests.

journal-api/src/commonMain/kotlin/pw/binom/agentik/journal/JournalStore.kt

@@ -18,6 +18,28 @@ interface JournalStore : AutoCloseable {
 
     suspend fun list(conversationId: String, after: Instant, offset: Int, limit: Int): List<MessageRecord>
 
+    /**
+     * Сколько сообщений в диалоге [conversationId] всего.
+     *
+     * O(1) на SQL-бэкендах (`SELECT COUNT(*) ... WHERE conversation_id = ?`),
+     * O(N) на in-memory (size простого list'а с фильтром по conversationId).
+     * Не зависит от cursor'а [after] — для total-размера диалога.
+     */
+    suspend fun count(conversationId: String): Long
+
+    /**
+     * Сколько сообщений в диалоге [conversationId] создано **позже** [after]
+     * (строго `createdAt > after`, как и в [list]).
+     *
+     * O(1) на SQL-бэкендах, O(N) на in-memory. Полезно для:
+     *  - UI badge "N новых сообщений" — клиент знает последний `lastSeen`,
+     *    сервер говорит `count(convId, after=lastSeen)`;
+     *  - пагинации без получения самих записей: знаем лимит последней страницы,
+     *    надо понять "есть ли ещё";
+     *  - compaction-метрик: «сколько turn'ов осталось после cutoff».
+     */
+    suspend fun count(conversationId: String, after: Instant): Long
+
     /**
      * Cold-flow paging через [list]. Default-реализация делает N+1 round-trip
      * (по странице через `list()` пока не получит короткую страницу). Для

journal-inmemory/src/commonMain/kotlin/pw/binom/agentik/journal/inmemory/InMemoryJournalStore.kt

@@ -59,6 +59,14 @@ class InMemoryJournalStore : MutableJournalStore {
         records.removeAll { it.conversationId == conversationId }
     }
 
+    override suspend fun count(conversationId: String): Long = mutex.withLock {
+        records.count { it.conversationId == conversationId }.toLong()
+    }
+
+    override suspend fun count(conversationId: String, after: Instant): Long = mutex.withLock {
+        records.count { it.conversationId == conversationId && it.createdAt > after }.toLong()
+    }
+
     /** Сколько записей сейчас в кэше. Для тестов/диагностики. */
     suspend fun size(): Int = mutex.withLock { records.size }
 

journal-inmemory/src/commonTest/kotlin/pw/binom/agentik/journal/inmemory/InMemoryJournalStoreTest.kt

@@ -77,4 +77,85 @@ class InMemoryJournalStoreTest {
         assertTrue(store.list("c1", Instant.DISTANT_PAST, 0, 100).isEmpty())
         assertEquals(listOf("m2"), store.list("c2", Instant.DISTANT_PAST, 0, 100).map { it.id })
     }
+
+    @Test
+    fun `count returns total per conversation`() = runTest {
+        val store = InMemoryJournalStore()
+        val t0 = Instant.parse("2026-09-21T10:00:00Z")
+        assertEquals(0L, store.count("c1"))
+
+        store.append(userMsg("m1", "c1", "a", t0))
+        store.append(userMsg("m2", "c1", "b", t0 + 1.seconds))
+        store.append(userMsg("m3", "c2", "c", t0 + 2.seconds))
+
+        assertEquals(2L, store.count("c1"))
+        assertEquals(1L, store.count("c2"))
+        assertEquals(0L, store.count("never-existed"))
+    }
+
+    @Test
+    fun `count is unaffected by clear of another conversation`() = runTest {
+        val store = InMemoryJournalStore()
+        val t0 = Instant.parse("2026-09-21T10:00:00Z")
+        for (i in 1..20) {
+            store.append(userMsg("m$i", "c1", "x", t0 + i.seconds))
+        }
+        store.append(userMsg("n1", "c2", "y", t0))
+        assertEquals(20L, store.count("c1"))
+        assertEquals(1L, store.count("c2"))
+
+        store.clear("c1")
+        assertEquals(0L, store.count("c1"))
+        assertEquals(1L, store.count("c2"))
+    }
+
+    @Test
+    fun `count after cursor excludes earlier messages`() = runTest {
+        val store = InMemoryJournalStore()
+        val t0 = Instant.parse("2026-09-21T10:00:00Z")
+        store.append(userMsg("m1", "c1", "a", t0))
+        store.append(userMsg("m2", "c1", "b", t0 + 10.seconds))
+        store.append(userMsg("m3", "c1", "c", t0 + 20.seconds))
+
+        // strictly > t0
+        assertEquals(2L, store.count("c1", t0))
+        // strictly > t0+10s — only the last
+        assertEquals(1L, store.count("c1", t0 + 10.seconds))
+        // after last — empty
+        assertEquals(0L, store.count("c1", t0 + 20.seconds))
+        // distant past — all
+        assertEquals(3L, store.count("c1", Instant.DISTANT_PAST))
+    }
+
+    @Test
+    fun `count after cursor scopes to conversation`() = runTest {
+        val store = InMemoryJournalStore()
+        val t = Instant.parse("2026-09-21T10:00:00Z")
+        store.append(userMsg("m1", "c1", "a", t))
+        store.append(userMsg("m2", "c2", "b", t))
+
+        val future = Instant.parse("2099-01-01T00:00:00Z")
+        assertEquals(0L, store.count("c1", future))
+        assertEquals(0L, store.count("c2", future))
+        assertEquals(1L, store.count("c1", Instant.DISTANT_PAST))
+        assertEquals(1L, store.count("c2", Instant.DISTANT_PAST))
+    }
+
+    @Test
+    fun `count agrees with list size`() = runTest {
+        val store = InMemoryJournalStore()
+        val t0 = Instant.parse("2026-09-21T10:00:00Z")
+        for (i in 1..15) {
+            store.append(userMsg("m$i", "c1", "x", t0 + i.seconds))
+        }
+        assertEquals(
+            store.list("c1", Instant.DISTANT_PAST, 0, 1000).size.toLong(),
+            store.count("c1"),
+        )
+        val cutoff = t0 + 7.seconds
+        assertEquals(
+            store.list("c1", cutoff, 0, 1000).size.toLong(),
+            store.count("c1", cutoff),
+        )
+    }
 }

journal-ksqlite/src/commonMain/kotlin/pw/binom/agentik/journal/ksqlite/KsqliteJournalStore.kt

@@ -100,6 +100,16 @@ class KsqliteJournalStore private constructor(
     private val clearStmt: SQLitePreparedStatement = connection.prepare(
         "DELETE FROM ${Schema.TABLE_MESSAGE} WHERE ${Schema.COL_CONVERSATION_ID} = ?"
     )
+    private val countAllStmt: SQLitePreparedStatement = connection.prepare(
+        "SELECT COUNT(*) FROM ${Schema.TABLE_MESSAGE} WHERE ${Schema.COL_CONVERSATION_ID} = ?"
+    )
+    private val countAfterStmt: SQLitePreparedStatement = connection.prepare(
+        """
+        SELECT COUNT(*) FROM ${Schema.TABLE_MESSAGE}
+        WHERE ${Schema.COL_CONVERSATION_ID} = ?
+          AND ${Schema.COL_CREATED_AT} > ?
+        """.trimIndent()
+    )
 
     override suspend fun append(record: MessageRecord): Unit = withContext(Dispatchers.Default) {
         val (kind, payload) = encodeRecord(record)
@@ -147,10 +157,37 @@ class KsqliteJournalStore private constructor(
         }
     }
 
+    override suspend fun count(conversationId: String): Long = withContext(Dispatchers.Default) {
+        mutex.withLock {
+            countAllStmt.reset()
+            countAllStmt.clearBindings()
+            countAllStmt.bindText(1, conversationId)
+            countAllStmt.executeQuery().use { rs ->
+                check(rs.next()) { "COUNT(*) must return at least one row" }
+                (rs.getLong(0) ?: 0L)
+            }
+        }
+    }
+
+    override suspend fun count(conversationId: String, after: Instant): Long = withContext(Dispatchers.Default) {
+        mutex.withLock {
+            countAfterStmt.reset()
+            countAfterStmt.clearBindings()
+            countAfterStmt.bindText(1, conversationId)
+            countAfterStmt.bindLong(2, after.toEpochMilliseconds())
+            countAfterStmt.executeQuery().use { rs ->
+                check(rs.next()) { "COUNT(*) must return at least one row" }
+                (rs.getLong(0) ?: 0L)
+            }
+        }
+    }
+
     override fun close() {
         insertStmt.close()
         listStmt.close()
         clearStmt.close()
+        countAllStmt.close()
+        countAfterStmt.close()
         if (ownsConnection) {
             connection.close()
         }

journal-ksqlite/src/commonTest/kotlin/pw/binom/agentik/journal/ksqlite/KsqliteJournalStoreTest.kt

@@ -96,4 +96,93 @@ class KsqliteJournalStoreTest {
         assertEquals(emptyList(), store.listFlow("conv1", Instant.DISTANT_PAST).toList())
         assertEquals(1, store.listFlow("conv2", Instant.DISTANT_PAST).toList().size)
     }
+
+    @Test
+    fun testCountReturnsTotalForConversation() = runTest {
+        val t = Instant.parse("2026-09-15T10:00:00Z")
+        assertEquals(0L, store.count("conv1"))
+
+        store.append(MessageRecord.UserMessage("m1", "conv1", listOf(Content.Text("a")), t, null))
+        store.append(MessageRecord.UserMessage("m2", "conv1", listOf(Content.Text("b")), t, null))
+        store.append(MessageRecord.UserMessage("m3", "conv2", listOf(Content.Text("c")), t, null))
+
+        assertEquals(2L, store.count("conv1"))
+        assertEquals(1L, store.count("conv2"))
+        assertEquals(0L, store.count("missing"))
+    }
+
+    @Test
+    fun testCountIsolatedFromOtherConversations() = runTest {
+        val t = Instant.parse("2026-09-15T10:00:00Z")
+        // Bulk insert into conv1, single into conv2.
+        for (i in 1..50) {
+            store.append(MessageRecord.UserMessage("m$i", "conv1", listOf(Content.Text("x$i")), t, null))
+        }
+        store.append(MessageRecord.UserMessage("n1", "conv2", listOf(Content.Text("only")), t, null))
+
+        assertEquals(50L, store.count("conv1"))
+        assertEquals(1L, store.count("conv2"))
+        assertEquals(0L, store.count("never-existed"))
+    }
+
+    @Test
+    fun testCountAfterFiltersStrictly() = runTest {
+        val t1 = Instant.parse("2026-09-15T10:01:00Z")
+        val t2 = Instant.parse("2026-09-15T10:02:00Z")
+        val t3 = Instant.parse("2026-09-15T10:03:00Z")
+        store.append(MessageRecord.UserMessage("m1", "conv1", listOf(Content.Text("a")), t1, null))
+        store.append(MessageRecord.UserMessage("m2", "conv1", listOf(Content.Text("b")), t2, null))
+        store.append(MessageRecord.UserMessage("m3", "conv1", listOf(Content.Text("c")), t3, null))
+
+        // Strictly > — t1 is not counted when after=t1.
+        assertEquals(2L, store.count("conv1", t1))
+        // Strictly > — t2 IS counted (only t3 after).
+        assertEquals(1L, store.count("conv1", t2))
+        // After last — empty.
+        assertEquals(0L, store.count("conv1", t3))
+        // Distant past — all three.
+        assertEquals(3L, store.count("conv1", Instant.DISTANT_PAST))
+    }
+
+    @Test
+    fun testCountAfterIsolatesByConversation() = runTest {
+        val t = Instant.parse("2026-09-15T10:00:00Z")
+        store.append(MessageRecord.UserMessage("m1", "conv1", listOf(Content.Text("a")), t, null))
+        store.append(MessageRecord.UserMessage("m2", "conv2", listOf(Content.Text("b")), t, null))
+
+        // Cursor that excludes everything — both conversations read 0.
+        val future = Instant.parse("2099-01-01T00:00:00Z")
+        assertEquals(0L, store.count("conv1", future))
+        assertEquals(0L, store.count("conv2", future))
+        // Cursor that includes everything — only conv1's message matches its conversation.
+        assertEquals(1L, store.count("conv1", Instant.DISTANT_PAST))
+        assertEquals(1L, store.count("conv2", Instant.DISTANT_PAST))
+    }
+
+    @Test
+    fun testCountAgreesWithListSize() = runTest {
+        val t0 = Instant.parse("2026-09-15T10:00:00Z")
+        for (i in 1..10) {
+            store.append(
+                MessageRecord.UserMessage(
+                    id = "m$i",
+                    conversationId = "conv1",
+                    content = listOf(Content.Text("x$i")),
+                    createdAt = t0 + kotlin.time.Duration.parse("PT${i}S"),
+                    context = null,
+                ),
+            )
+        }
+        // count === list(..., 0, +∞).size
+        assertEquals(
+            store.list("conv1", Instant.DISTANT_PAST, 0, 1000).size.toLong(),
+            store.count("conv1"),
+        )
+        // count(after=t5) === list(..., after=t5, 0, +∞).size
+        val cutoff = t0 + kotlin.time.Duration.parse("PT5S")
+        assertEquals(
+            store.list("conv1", cutoff, 0, 1000).size.toLong(),
+            store.count("conv1", cutoff),
+        )
+    }
 }