From fad59e9a57342d571d9e7fd9bdabddbf32b0b321 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Thu, 6 Aug 2026 23:42:13 +0000
Subject: [PATCH 2/2] =?UTF-8?q?test(diag):=20cross-language=20wire-format?=
 =?UTF-8?q?=20golden=20=E2=80=94=20lock=20BlackBox=20codec=20=E2=87=84=20p?=
 =?UTF-8?q?ython=20decoder?=
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Golden fingerprint (payload hex + luma bit-placement CRC) computed by the offline python decoder
(scratchpad/blackbox/bb.py, verified end-to-end through real H.264: 30/30 frames exact at crf 23 and
28, fail-closed). This test asserts the Kotlin encoder reproduces it byte-for-byte, so the on-device
overlay and the agent's decoder cannot silently drift apart.
---
 .../mofe/diag/BlackBoxWireFormatTest.kt       | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 common/src/commonTest/kotlin/com/aether/mofe/diag/BlackBoxWireFormatTest.kt

diff --git a/common/src/commonTest/kotlin/com/aether/mofe/diag/BlackBoxWireFormatTest.kt b/common/src/commonTest/kotlin/com/aether/mofe/diag/BlackBoxWireFormatTest.kt
new file mode 100644
index 0000000..5c0d04d
--- /dev/null
+++ b/common/src/commonTest/kotlin/com/aether/mofe/diag/BlackBoxWireFormatTest.kt
@@ -0,0 +1,33 @@
+package com.aether.mofe.diag
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+/**
+ * Cross-language golden: locks the black-box wire format so the on-device Kotlin encoder and the agent's
+ * offline python decoder (scratchpad/blackbox/bb.py) stay byte-identical. The golden values were computed by
+ * the python port for the FIXED state below; if a future change to [BlackBoxCodec]/[BlackBoxSchema] drifts the
+ * format, this fails and the python decoder would silently mis-read real captures. Integer fields only ⇒ exact.
+ */
+class BlackBoxWireFormatTest {
+    @Test
+    fun wire_format_matches_the_cross_language_golden() {
+        val s = BlackBoxState(
+            frameIdx = 7, tEngineMicros = 1234567890123L,
+            ranges = listOf(BbRange("85b92d", distanceMm = 3697, sq = 90, rssiDbm = -91, azCentiDeg = 27010, elCentiDeg = 220)),
+            imu = listOf(BbImu(dtMicros = 5000, axMilli = 120, ayMilli = -30, azMilli = 9810, gxMilli = 5, gyMilli = -4, gzMilli = 2)),
+            pose = BbPose(xMm = 812, yMm = -1503, zMm = 1100, qwE4 = 9998, qxE4 = 100, qyE4 = -50, qzE4 = 30),
+        )
+        val payload = BlackBoxState.encode(s)
+        assertEquals(
+            "01000000070000011f71fb04cb010185b92d0e715aa5698200dc0113880078ffe226520005fffc0002032cfa21044c270e0064ffce001e",
+            payload.joinToString("") { (it.toInt() and 0xFF).toString(16).padStart(2, '0') },
+            "schema wire format drifted from the python decoder golden",
+        )
+        val luma = BlackBoxCodec.encodeToLuma(payload, cols = 80, rows = 130, repeat = 5)
+        assertEquals(930, luma.count { it == 255 }, "luma set-cell count drifted")
+        val lumaBytes = ByteArray(luma.size) { (luma[it] and 0xFF).toByte() }
+        assertEquals(0xc16edcfc.toInt(), BlackBoxCodec.crc32(lumaBytes), "luma bit-placement drifted from the golden")
+        assertEquals(s, BlackBoxState.decode(BlackBoxCodec.decodeFromLuma(luma, 80, 130, 5)!!), "must self-decode")
+    }
+}
-- 
2.43.0