feat(booth): blink the Entry/Exit lights on radar presence (mirror relay 3)

The on-screen Hyrje/Dalje barrier lights were 2-state (green=free / red=busy)
off the camera lane-status only — they couldn't show the radar-only "detected,
not yet confirmed" state that makes the physical button lamp (relay 3) blink.
Now they mirror the lamp's 3-state rule per lane:
  radar present + camera not busy → BLINK green↔red (~1 Hz)
  camera busy                     → SOLID red
  otherwise                       → SOLID green

End-to-end:
- LanePresence (lane-presence.ts): subscribes to deviceEvents.onInput, resolves
  each presence edge to its lane via the new direction-agnostic presenceLaneOf()
  (device-resolve.ts) — entry AND exit, unlike the entry-gated relayForPresence
  the one-car-one-ticket gate uses — and emits a lane-presence {entry,exit} bus
  event on change. Wired in server.ts (start + onClose).
- WS forwards it (hello snapshot + push) into live-store.radar.
- BarrierLight (BoothScreen.tsx) is now 3-state; blinks via the .lane-blink
  keyframe (index.css), which holds solid-red under prefers-reduced-motion.

Same input + same rule as the lamp, so the screen and the post never disagree.

A new test (lane-presence.test.ts) caught a real bug: the first cut reused
relayForPresence, so the EXIT lane never resolved (it's entry-gated) and never
blinked — presenceLaneOf fixes it. Covers entry/exit independence, de-dupe
across several radars on one lane, and ignoring non-presence inputs.

Full workspace build/lint/test green (185 server tests). Updated the
button-light-indicator wiki page ("On-screen twin").

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/web/src/lib/live-store.ts

@@ -16,6 +16,14 @@ export interface LaneStatus {
   exit: boolean; // true = busy
 }
 
+/** Per-lane RADAR presence — a presence input (loop/radar) is shorted at the barrier,
+ *  i.e. "something is in the lane" BEFORE the camera confirms a vehicle. Drives the
+ *  barrier light's BLINK (the same signal as the physical button lamp / relay 3). */
+export interface LanePresence {
+  entry: boolean; // true = a radar/presence input on an entry barrier is active
+  exit: boolean; // true = … on an exit barrier
+}
+
 /** Cap the in-memory live feed so a long-running booth session can't grow it
  *  unbounded — the full history is always available via the /api/events query. */
 const MAX_FEED = 200;
@@ -31,6 +39,8 @@ interface LiveState {
   devices: Record<string, DeviceStatus>;
   /** Per-lane busy/free (camera vehicle detection). Null until the first WS hello. */
   lanes: LaneStatus | null;
+  /** Per-lane radar presence (advisory blink). Null until the first WS hello. */
+  radar: LanePresence | null;
   setStatus: (s: WsStatus) => void;
   setOccupancy: (o: Occupancy) => void;
   pushEvent: (e: LedgerEvent) => void;
@@ -40,6 +50,8 @@ interface LiveState {
   upsertDevice: (d: DeviceStatus) => void;
   /** Set lane busy/free (WS hello + each lane-status push). */
   setLanes: (l: LaneStatus) => void;
+  /** Set lane radar presence (WS hello + each lane-presence push). */
+  setRadar: (r: LanePresence) => void;
   reset: () => void;
 }
 
@@ -56,6 +68,7 @@ export const useLiveStore = create<LiveState>((set) => ({
   feed: [],
   devices: {},
   lanes: null,
+  radar: null,
   setStatus: (status) => set({ status }),
   setOccupancy: (occupancy) => set({ occupancy }),
   pushEvent: (e) =>
@@ -66,5 +79,6 @@ export const useLiveStore = create<LiveState>((set) => ({
   setDevices: (list) => set({ devices: byId(list) }),
   upsertDevice: (d) => set((s) => ({ devices: { ...s.devices, [d.deviceId]: d } })),
   setLanes: (lanes) => set({ lanes }),
-  reset: () => set({ status: "connecting", occupancy: null, feed: [], devices: {}, lanes: null }),
+  setRadar: (radar) => set({ radar }),
+  reset: () => set({ status: "connecting", occupancy: null, feed: [], devices: {}, lanes: null, radar: null }),
 }));

apps/web/src/lib/use-live-feed.ts

@@ -2,7 +2,7 @@ import { useEffect, useRef } from "react";
 import { useQueryClient } from "@tanstack/react-query";
 import type { DeviceStatus, LedgerEvent, Occupancy } from "../api.js";
 import { qk } from "./query.js";
-import { useLiveStore, type LaneStatus } from "./live-store.js";
+import { useLiveStore, type LaneStatus, type LanePresence } from "./live-store.js";
 import { wsUrl } from "./origin.js";
 
 // Booth WebSocket client. Opens ONE socket to /api/ws and turns server pushes into
@@ -14,16 +14,17 @@ import { wsUrl } from "./origin.js";
 
 /** Server → client message shapes (mirror routes/ws.ts OutMsg). */
 type WsMessage =
-  | { kind: "hello"; occupancy: Occupancy; devices: DeviceStatus[]; lanes: LaneStatus }
+  | { kind: "hello"; occupancy: Occupancy; devices: DeviceStatus[]; lanes: LaneStatus; radar: LanePresence }
   | { kind: "ledger"; event: LedgerEvent; occupancy: Occupancy }
   | { kind: "printer-status"; event: unknown }
   | { kind: "device-status"; event: DeviceStatus }
-  | { kind: "lane-status"; lanes: LaneStatus };
+  | { kind: "lane-status"; lanes: LaneStatus }
+  | { kind: "lane-presence"; radar: LanePresence };
 
 
 export function useLiveFeed(): void {
   const qc = useQueryClient();
-  const { setStatus, setOccupancy, pushEvent, setDevices, upsertDevice, setLanes } = useLiveStore();
+  const { setStatus, setOccupancy, pushEvent, setDevices, upsertDevice, setLanes, setRadar } = useLiveStore();
   // Hold the socket + reconnect timer across renders; guard against StrictMode
   // double-invoke and unmount.
   const sockRef = useRef<WebSocket | null>(null);
@@ -56,10 +57,13 @@ export function useLiveFeed(): void {
           // Initial device-status snapshot for the footer.
           if (Array.isArray(msg.devices)) setDevices(msg.devices);
           if (msg.lanes) setLanes(msg.lanes);
+          if (msg.radar) setRadar(msg.radar);
         } else if (msg.kind === "device-status") {
           upsertDevice(msg.event);
         } else if (msg.kind === "lane-status") {
           setLanes(msg.lanes);
+        } else if (msg.kind === "lane-presence") {
+          setRadar(msg.radar);
         } else if (msg.kind === "ledger") {
           setOccupancy(msg.occupancy);
           pushEvent(msg.event);