Validate stream snapshot counts and verify native metadata mappings

tools/chatgui-android/app/src/test/java/com/utun/chat/data/StreamMetadataTest.kt

@@ -0,0 +1,46 @@
+package com.utun.chat.data
+
+import org.junit.Assert.*
+import org.junit.Test
+
+class StreamMetadataTest {
+    @Test fun sourceIdsAndEpochsPreserveUnsigned64BitsAndEmptyNamesUseTheId() {
+        val source = StreamSource.parse("""[{"id":"18446744073709551615","epoch":"ffffffffffffffff","name":"","self":1}]""").single()
+        assertEquals(-1L, source.id); assertEquals(-1L, source.epoch)
+        assertEquals("18446744073709551615", source.displayName); assertTrue(source.self)
+    }
+
+    @Test fun sourceSnapshotsRejectZeroAndDuplicateIdentities() {
+        for (json in listOf("""[{"id":"0","epoch":"1","name":"a","self":0}]""",
+            """[{"id":"1","epoch":"0","name":"a","self":0}]""",
+            """[{"id":"1","epoch":"a","name":"a","self":0},{"id":"1","epoch":"b","name":"b","self":1}]""")) {
+            assertThrows(IllegalArgumentException::class.java) { StreamSource.parse(json) }
+        }
+    }
+
+    @Test fun transmitSnapshotMapsUnitsAndKeepsUnsignedPeerId() {
+        val data = longArrayOf(100, 1, 2, 3, 4, 5, 6, 7, 8, 10, 20, 2, 1, -1, 12, 18, 3)
+        val stats = StreamTxStats.fromNative(42, data)
+        assertEquals(100L, stats.sampleUs); assertEquals(8L, stats.connections); assertEquals(6L, stats.acked1s)
+        assertEquals(2, stats.buffer.total); assertEquals(StreamBufferPeer(-1, 12, 18, 3), stats.buffer.peers.single())
+        assertEquals(0f, stats.buffer.fraction(0), 0f); assertEquals(0.5f, stats.buffer.fraction(15), 0f)
+        assertEquals(1f, stats.buffer.fraction(30), 0f); assertEquals(1f, StreamBufferPositions().fraction(0), 0f)
+    }
+
+    @Test fun malformedStatsCannotOverflowCountsOrReverseTheBufferWindow() {
+        val valid = longArrayOf(100, 1, 2, 3, 4, 5, 6, 7, 8, 10, 20, 2, 1, -1, 12, 18, 3)
+        for (data in listOf(valid.copyOf(12), valid + 0, valid.copyOf().also { it[11] = Int.MAX_VALUE.toLong() + 1 },
+            valid.copyOf().also { it[9] = 21 }, valid.copyOf().also { it[12] = 17 },
+            valid.copyOf().also { it[15] = 11 }, valid.copyOf().also { it[16] = 256 })) {
+            assertThrows(IllegalArgumentException::class.java) { StreamTxStats.fromNative(42, data) }
+        }
+    }
+
+    @Test fun nativeTelemetryKeepsKnownUnknownAndLocalReserveSeparate() {
+        val data = """{"self":"local","nodes":[{"name":"relay","flags":7,"us":2000000,"frames":4},{"name":"source","flags":0,"us":0,"frames":0}]}"""
+        val stats = StreamPlaybackTelemetry.fromNative(data.toByteArray(), 500000, 1100)
+        assertEquals(3, stats.nodes.size); assertEquals(2_000_000L, stats.nodes[0].durationUs)
+        assertTrue(stats.nodes[0].stale); assertTrue(stats.nodes[0].down); assertNull(stats.nodes[1].durationUs)
+        assertEquals(500_000L, stats.nodes[2].durationUs); assertEquals("1.1x", stats.speed)
+    }
+}