OBD-II signals renamed obd_*, plus timing, trims, O2; GNSS signals; elm_connected; reboot command

Decision 30: CAN feeds displays, OBD-II (K-line via the ELM) calibrates, so every
obd2 signal carries the obd_ prefix and the plain names are left for decoded ones.
yukart/gnss/<signal> gives displays the fix as single values; gnss/fix stays for
navigation. Boundary: reboot beside poweroff, same guards.

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

docs/BOUNDARY.md

@@ -37,7 +37,7 @@ The two channels from decision 24 share the socket but keep different guarantees
 | `ack` | reply to a `cmd` | `id`, `ok`, `detail`, `dup` (true when answered from the cache) |
 
 With `source: bus`, `signals` is the newest envelope of every signal svc-gw has
-seen on `yukart/vehicle/+` and `yukart/host/+`. svc-gw marks one
+seen on `yukart/vehicle/+`, `yukart/host/+` and `yukart/gnss/+`. svc-gw marks one
 `quality: "stale"` when it has not been refreshed for 5 s, or is known only from
 the broker's retained copy (which may predate a reboot). A signal once seen is
 never removed.
@@ -66,18 +66,20 @@ tablet, or an Orin behind a replugged hub, looks connected at the link layer.
 |---|---|---|
 | `ping` | — | `ack` with `detail: "pong"` |
 | `mark` | `text`, `delay_ms` (optional: how long the command waited before this send) | stamped into the open recording; fails with no session open |
-| `poweroff` | `confirm: "poweroff"`, `boot_id` (from this connection's `hello`) | acks, then shuts the host down cleanly (`systemctl poweroff`) about 2 s later. Refused unless svc-gw runs with `--allow-poweroff` (the Orin's unit only), and when `boot_id` is not the current boot's |
+| `poweroff` | `confirm: "poweroff"`, `boot_id` (from this connection's `hello`) | acks, then shuts the host down cleanly (`systemctl poweroff`) about 2 s later. Refused unless svc-gw runs with `--allow-power` (the Orin's unit only), and when `boot_id` is not the current boot's |
+| `reboot` | `confirm: "reboot"`, `boot_id` | the same, with `systemctl reboot`; the same flag and refusals |
 
 A repeated `id` returns the original `ack` (last 256 kept, shared across
 connections) and never re-runs the command.
 
-`poweroff` is the exception to retry-until-acked: the ack cache does not survive
+`poweroff` and `reboot` are the exception to retry-until-acked: the ack cache does
-the reboot it causes, so a resend could shut the next boot down too. The client
+not survive the restart they cause, so a resend could shut the next boot down (or
-sends it once and does not resend it; `boot_id` makes svc-gw refuse one from a
+reboot it again). The client sends them once and does not resend; `boot_id` makes
-previous boot regardless.
+svc-gw refuse one from a previous boot regardless.
 
 ## Not yet
 
 - TTS utterances (id, chunk sequence, terminator, expiry) — when there is a TTS.
-- `gnss`: its fix is an object, which the envelope's `value` does not allow yet.
+- `gnss/fix` as one object (navigation's input): the envelope's `value` does not allow
+  one yet. Displays get the fix as single values on `yukart/gnss/<signal>` instead.
 - Any version beyond `proto: 0`. A breaking change bumps it; the client checks it.

docs/GUIDELINES.md

@@ -9,7 +9,7 @@ type: guidelines
 - ⚠ **The unit appears in both the topic name and the payload, so they can
   contradict each other.** Generating both from one entry is what stops that; a
   hand-written `"unit"` reintroduces the failure it was meant to prevent.
-- Signal names carry their unit (`vehicle_speed_kph`, `coolant_temp_c`), so a unit
+- Signal names carry their unit (`gnss_speed_kph`, `obd_coolant_temp_c`), so a unit
   mismatch is visible at the call site rather than one registry lookup away.
 
 ## 2. Two clocks, and they answer different questions

schema/signals.json

@@ -1,6 +1,136 @@
 {
-  "$comment": "Single source for signal identity. Topic name and envelope unit are both derived from these entries and are never authored separately. source=obd2 is standardised; source=host is the Orin itself (orin-status), not the car. source=z27ag is reverse-engineered from the car's own broadcast frames, and its 'can' block is the only place its layout is written down: id (11-bit, hex string), byte (first data byte, 0-7), length in bits (1, 8 or 16), bit (length 1 only: 0 = LSB of that byte), order (length 16: big = byte first is most significant, little = the reverse), scale and offset (value = raw * scale + offset; booleans are raw != 0). 'evidence' names the contracts report that found it.",
+  "$comment": "Single source for signal identity. Topic name and envelope unit are both derived from these entries and are never authored separately. source=obd2 is standardised (OBD-II mode 01 over the K-line, through the ELM327): calibration references, every name prefixed obd_ (project-yukart decision 30); source=host is the Orin itself (orin-status), not the car. source=gnss is the receiver (svc-core gnss), on yukart/gnss/<signal>. source=z27ag is reverse-engineered from the car's own broadcast frames, and its 'can' block is the only place its layout is written down: id (11-bit, hex string), byte (first data byte, 0-7), length in bits (1, 8 or 16), bit (length 1 only: 0 = LSB of that byte), order (length 16: big = byte first is most significant, little = the reverse), scale and offset (value = raw * scale + offset; booleans are raw != 0). 'evidence' names the contracts report that found it.",
   "signals": {
+    "obd_vehicle_speed_kph": {
+      "unit": "kph",
+      "type": "number",
+      "source": "obd2",
+      "description": "Road speed",
+      "range": [
+        0,
+        255
+      ]
+    },
+    "obd_coolant_temp_c": {
+      "unit": "celsius",
+      "type": "number",
+      "source": "obd2",
+      "description": "Engine coolant temperature",
+      "range": [
+        -40,
+        215
+      ]
+    },
+    "obd_intake_air_temp_c": {
+      "unit": "celsius",
+      "type": "number",
+      "source": "obd2",
+      "description": "Intake air temperature",
+      "range": [
+        -40,
+        215
+      ]
+    },
+    "obd_throttle_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Throttle position",
+      "range": [
+        0,
+        100
+      ]
+    },
+    "obd_engine_load_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Calculated engine load",
+      "range": [
+        0,
+        100
+      ]
+    },
+    "obd_fuel_level_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Fuel tank level",
+      "range": [
+        0,
+        100
+      ]
+    },
+    "obd_intake_pressure_kpa": {
+      "unit": "kpa",
+      "type": "number",
+      "source": "obd2",
+      "description": "Intake manifold absolute pressure",
+      "range": [
+        0,
+        255
+      ]
+    },
+    "obd_maf_gps": {
+      "unit": "g/s",
+      "type": "number",
+      "source": "obd2",
+      "description": "Mass air flow rate",
+      "range": [
+        0,
+        656
+      ]
+    },
+    "obd_engine_rpm": {
+      "unit": "rpm",
+      "type": "number",
+      "source": "obd2",
+      "description": "Engine speed (OBD-II 0C): the reference for the decoded engine_rpm",
+      "range": [
+        0,
+        8000
+      ]
+    },
+    "obd_timing_advance_deg": {
+      "unit": "degree",
+      "type": "number",
+      "source": "obd2",
+      "description": "Ignition timing advance before TDC, cylinder 1",
+      "range": [
+        -64,
+        64
+      ]
+    },
+    "obd_stft_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Short-term fuel trim, bank 1: positive adds fuel",
+      "range": [
+        -100,
+        100
+      ]
+    },
+    "obd_ltft_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Long-term fuel trim, bank 1: positive adds fuel",
+      "range": [
+        -100,
+        100
+      ]
+    },
+    "obd_o2_b1s1_v": {
+      "unit": "V",
+      "type": "number",
+      "source": "obd2",
+      "description": "Upstream oxygen sensor voltage (narrowband: ~0.1 lean … ~0.9 rich)",
+      "range": [
+        0,
+        1.275
+      ]
+    },
     "engine_rpm": {
       "unit": "rpm",
       "type": "number",
@@ -20,86 +150,6 @@
         "evidence": "Z27AG-DECODE-1"
       }
     },
-    "vehicle_speed_kph": {
-      "unit": "kph",
-      "type": "number",
-      "source": "obd2",
-      "description": "Road speed",
-      "range": [
-        0,
-        255
-      ]
-    },
-    "coolant_temp_c": {
-      "unit": "celsius",
-      "type": "number",
-      "source": "obd2",
-      "description": "Engine coolant temperature",
-      "range": [
-        -40,
-        215
-      ]
-    },
-    "intake_air_temp_c": {
-      "unit": "celsius",
-      "type": "number",
-      "source": "obd2",
-      "description": "Intake air temperature",
-      "range": [
-        -40,
-        215
-      ]
-    },
-    "throttle_pct": {
-      "unit": "percent",
-      "type": "number",
-      "source": "obd2",
-      "description": "Throttle position",
-      "range": [
-        0,
-        100
-      ]
-    },
-    "engine_load_pct": {
-      "unit": "percent",
-      "type": "number",
-      "source": "obd2",
-      "description": "Calculated engine load",
-      "range": [
-        0,
-        100
-      ]
-    },
-    "fuel_level_pct": {
-      "unit": "percent",
-      "type": "number",
-      "source": "obd2",
-      "description": "Fuel tank level",
-      "range": [
-        0,
-        100
-      ]
-    },
-    "intake_pressure_kpa": {
-      "unit": "kpa",
-      "type": "number",
-      "source": "obd2",
-      "description": "Intake manifold absolute pressure",
-      "range": [
-        0,
-        255
-      ]
-    },
-    "maf_gps": {
-      "unit": "g/s",
-      "type": "number",
-      "source": "obd2",
-      "description": "Mass air flow rate",
-      "range": [
-        0,
-        656
-      ]
-    },
     "accel_pedal_pct": {
       "unit": "percent",
       "type": "number",
@@ -477,6 +527,12 @@
         10000
       ]
     },
+    "elm_connected": {
+      "unit": "",
+      "type": "boolean",
+      "source": "host",
+      "description": "Bluetooth link to the OBD-II adapter (the ELM327 on the K-line) is up: obd-poller holds it while the ECU answers"
+    },
     "ups_battery_v": {
       "unit": "V",
       "type": "number",
@@ -512,6 +568,72 @@
       "type": "string",
       "source": "host",
       "description": "charging, discharging (running on battery) or idle (on input power, not charging)"
+    },
+    "gnss_fix": {
+      "unit": "",
+      "type": "string",
+      "source": "gnss",
+      "description": "Fix quality: none, 2d or 3d (gpsd TPV mode)"
+    },
+    "gnss_speed_kph": {
+      "unit": "kph",
+      "type": "number",
+      "source": "gnss",
+      "description": "Speed over ground; null without a fix",
+      "range": [
+        0,
+        300
+      ]
+    },
+    "gnss_heading_deg": {
+      "unit": "degree",
+      "type": "number",
+      "source": "gnss",
+      "description": "Course over ground, true north; null without a fix or at a standstill",
+      "range": [
+        0,
+        360
+      ]
+    },
+    "gnss_lat": {
+      "unit": "degree",
+      "type": "number",
+      "source": "gnss",
+      "description": "Latitude, WGS84",
+      "range": [
+        -90,
+        90
+      ]
+    },
+    "gnss_lon": {
+      "unit": "degree",
+      "type": "number",
+      "source": "gnss",
+      "description": "Longitude, WGS84",
+      "range": [
+        -180,
+        180
+      ]
+    },
+    "gnss_alt_m": {
+      "unit": "m",
+      "type": "number",
+      "source": "gnss",
+      "description": "Altitude above mean sea level; null without a 3D fix",
+      "range": [
+        -500,
+        9000
+      ]
+    },
+    "gnss_satellites": {
+      "unit": "",
+      "type": "number",
+      "source": "gnss",
+      "description": "Satellites used in the fix",
+      "range": [
+        0,
+        64
+      ]
     }
   }
 }

schema/topics.json

@@ -12,7 +12,7 @@
       "payload": "envelope",
       "retained": true,
       "rate": "1-50/s",
-      "publisher": "decoder, obd-poller",
+      "publisher": "decoder (source z27ag), obd-poller (source obd2)",
       "description": "One topic per signal, named exactly as in signals.json."
     },
     "yukart/gnss/fix": {
@@ -22,6 +22,13 @@
       "publisher": "gnss",
       "description": "value is an object: lat, lon, alt_m, speed_kph, heading_deg, fix, satellites."
     },
+    "yukart/gnss/<signal>": {
+      "payload": "envelope",
+      "retained": true,
+      "rate": "1-10/s",
+      "publisher": "gnss",
+      "description": "The receiver's fix as single values, one topic per signal, named exactly as in signals.json (source=gnss). For displays; yukart/gnss/fix stays the composite for navigation."
+    },
     "yukart/host/<signal>": {
       "payload": "envelope",
       "retained": true,