Z27AG decode pass 2: vehicle speed, coolant, front wiper; wheel speeds little-endian; IMU checked against GNSS

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

schema/signals.json

@@ -250,7 +250,7 @@
       "unit": "",
       "type": "boolean",
       "source": "z27ag",
-      "description": "Any door open",
+      "description": "Any door open, the tailgate included (the bonnet has no switch)",
       "can": {
         "id": "0x423",
         "byte": 2,
@@ -263,7 +263,7 @@
       "unit": "",
       "type": "boolean",
       "source": "z27ag",
-      "description": "Driver's door open",
+      "description": "Driver's door open: the only door with its own bit",
       "can": {
         "id": "0x423",
         "byte": 0,
@@ -285,6 +285,56 @@
         "evidence": "Z27AG-DECODE-1"
       }
     },
+    "vehicle_speed_kph": {
+      "unit": "kph",
+      "type": "number",
+      "source": "z27ag",
+      "description": "Road speed from the ABS (CAN), scaled against GNSS on this car's tyres: OBD-II speed reads 3 % lower",
+      "range": [
+        0,
+        250
+      ],
+      "can": {
+        "id": "0x231",
+        "byte": 6,
+        "length": 16,
+        "order": "little",
+        "scale": 0.0577,
+        "offset": 0,
+        "evidence": "Z27AG-DECODE-2"
+      }
+    },
+    "coolant_temp_c": {
+      "unit": "celsius",
+      "type": "number",
+      "source": "z27ag",
+      "description": "Engine coolant temperature (CAN): equal to OBD-II's within 1 °C over 86-97 °C",
+      "range": [
+        -40,
+        215
+      ],
+      "can": {
+        "id": "0x449",
+        "byte": 2,
+        "length": 8,
+        "scale": 1,
+        "offset": -40,
+        "evidence": "Z27AG-DECODE-2"
+      }
+    },
+    "front_wiper": {
+      "unit": "",
+      "type": "boolean",
+      "source": "z27ag",
+      "description": "Front wiper running (low or high; interval not seen in a 4 s window). Medium confidence",
+      "can": {
+        "id": "0x423",
+        "byte": 3,
+        "bit": 3,
+        "length": 1,
+        "evidence": "Z27AG-DECODE-2"
+      }
+    },
     "orin_cpu_temp_c": {
       "unit": "celsius",
       "type": "number",