fix(anpr): abort the poll loop if the subscriber transacts by card/QR mid-poll

The poll-until-confident loop (prev commit) opened a race: during its ~8s window a
subscriber could scan their card/QR at the reader and exit immediately — but the ANPR
loop kept polling and would ALSO emit a confident read a moment later, exiting the
NEXT open occurrence (a phantom double-exit, worst for a fleet sub with several open).

Guard it with the subscriber's open-occurrence count: the bridge identifies the
subscription as soon as a frame reads the bound plate (identity needs no confidence),
baselines openOccurrenceCount, then each tick AND before emit checks if it moved. If a
credential closed/opened an occurrence mid-poll, the subscriber already transacted →
abort, don't emit. New public SubscriptionFlow.openOccurrenceCount(). Bounded loop is
unchanged (ANPR_POLL_WINDOW_MS=8000 cap; never infinite).

+1 test (credential transacts mid-poll → no double-act); 170 server tests green.

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

apps/server/src/anpr-entry.test.ts

@@ -86,8 +86,17 @@ function fakeVision(opts: { enabled?: boolean; plate?: string; confidence?: numb
 }
 
 /** A fake SubscriptionFlow: only `match()` is called by the bridge. */
-function fakeSubFlow(match: SubscriptionMatch | null): SubscriptionFlow {
-  return { match: vi.fn(() => match) } as unknown as SubscriptionFlow;
+function fakeSubFlow(
+  match: SubscriptionMatch | null,
+  // openOccurrenceCount: a constant, or a sequence consumed per call (to simulate a
+  // credential closing an occurrence mid-poll → count changes).
+  openCounts: number | number[] = 1,
+): SubscriptionFlow {
+  const seq = Array.isArray(openCounts) ? [...openCounts] : null;
+  return {
+    match: vi.fn(() => match),
+    openOccurrenceCount: vi.fn(() => (seq ? (seq.length > 1 ? seq.shift()! : seq[0]) : (openCounts as number))),
+  } as unknown as SubscriptionFlow;
 }
 
 const SUB_MATCH: SubscriptionMatch = { subscriptionId: "sub-1", carKey: "AA111BB", via: "plate" };
@@ -152,6 +161,10 @@ describe("AnprBridge", () => {
         tookMs: 1,
       })),
     } as unknown as VisionClient;
+    // Generous window so all 3 escalation attempts run deterministically under suite load
+    // (the global beforeEach sets a tiny 5ms window for the give-up cases).
+    process.env.ANPR_POLL_MS = "1";
+    process.env.ANPR_POLL_WINDOW_MS = "2000";
     const bridge = new AnprBridge(db, vision, fakeSubFlow(SUB_MATCH), silentLogger());
 
     const reads = await captureReads(() => bridge.onVehicleDetected(cam));
@@ -160,6 +173,20 @@ describe("AnprBridge", () => {
     expect(captureSnapshot.mock.calls.length).toBeGreaterThanOrEqual(3); // re-pulled fresh frames
   });
 
+  it("ABORTS if the subscriber transacts by another credential mid-poll (no double-act)", async () => {
+    // The car's plate is read (identity known) but stays below the floor; meanwhile the
+    // subscriber scans their card → openOccurrenceCount drops. The bridge must abort and NOT
+    // emit (which would exit the NEXT open occurrence — a phantom double-exit, esp. fleet).
+    const cam = seedCamera({ anpr: true });
+    const vision = fakeVision({ plate: "AA111BB", confidence: 0.5 }); // never clears the floor
+    // openOccurrenceCount: 1 at baseline, then 0 (the card exit closed it) on the next check.
+    const sub = fakeSubFlow(SUB_MATCH, [1, 0]);
+    const bridge = new AnprBridge(db, vision, sub, silentLogger());
+
+    const reads = await captureReads(() => bridge.onVehicleDetected(cam));
+    expect(reads).toEqual([]); // aborted — the credential already handled it
+  });
+
   it("does NOT emit for a plate matching no subscription — records an advisory anpr-skip", async () => {
     const cam = seedCamera({ anpr: true });
     const vision = fakeVision({ plate: "ZZ999ZZ", confidence: 0.97 });

apps/server/src/anpr-entry.ts

@@ -68,6 +68,12 @@ function pollWindowMs(): number {
 
 const sleep = (ms: number) => new Promise<void>((r) => setTimeout(r, ms));
 
+/** A plate DeviceReadEvent skeleton (value filled by the caller) — for matching the
+ *  subscriber by plate during the poll loop without re-building the whole event. */
+function baseRead(row: { driverId: string }, deviceId: string): Omit<DeviceReadEvent, "value"> {
+  return { driverId: row.driverId, deviceId, kind: "plate", at: new Date().toISOString() };
+}
+
 export class AnprBridge {
   readonly #db: Db;
   readonly #vision: VisionClient | null;
@@ -138,7 +144,15 @@ export class AnprBridge {
       // pull a FRESH frame every #pollMs and re-run ANPR until one clears the floor, or the
       // #pollWindowMs window elapses (car drove off / non-subscriber). NB: a fresh pull each
       // tick — NOT captureSnapshotShared, whose TTL would re-serve the same bad frame.
+      // While polling, watch whether THIS subscriber transacts by another credential
+      // (card/QR at the reader). If their open-occurrence count drops mid-poll, the
+      // subscriber already exited/entered — the bridge must NOT also emit (it would act on
+      // the NEXT open occurrence: a phantom double-exit, worst for a fleet sub). We learn the
+      // subscription as soon as a frame reads the bound plate (identity needs no confidence),
+      // snapshot the count, then keep polling for a CONFIDENT read; abort if the count moved.
       let result: Awaited<ReturnType<VisionClient["analyze"]>> = null;
+      let watchedSubId: string | null = null;
+      let baselineOpen = 0;
       const deadline = Date.now() + this.#pollWindowMs;
       let attempts = 0;
       try {
@@ -146,6 +160,25 @@ export class AnprBridge {
           attempts++;
           const shot = await camera.captureSnapshot({ direction });
           const r = await this.#vision.analyze(shot.bytes, shot.contentType);
+
+          // Identify the subscriber from ANY readable plate (even below the barrier floor),
+          // and baseline their open count once — so we can detect a credential beating us.
+          if (r?.plate?.text) {
+            const m0 = this.#subscription.match({ ...baseRead(row, deviceId), value: r.plate.text.trim().toUpperCase() });
+            if (m0 && watchedSubId == null) {
+              watchedSubId = m0.subscriptionId;
+              baselineOpen = this.#subscription.openOccurrenceCount(watchedSubId);
+            }
+          }
+          // A credential (card/QR) closed/opened an occurrence for this subscriber mid-poll →
+          // they already transacted; stop polling and do NOT emit.
+          if (watchedSubId && this.#subscription.openOccurrenceCount(watchedSubId) !== baselineOpen) {
+            this.#logger.info(
+              `anpr-bridge: subscriber ${watchedSubId} transacted by another credential mid-poll — aborting ANPR`,
+            );
+            return;
+          }
+
           if (r?.plate && r.plate.confidence >= this.#entryMinConfidence) {
             result = r;
             break;
@@ -190,6 +223,13 @@ export class AnprBridge {
         return;
       }
 
+      // Final guard against the credential-mid-poll race: if the subscriber transacted between
+      // our baseline and now (e.g. a card scan in the last tick), don't double-act.
+      if (watchedSubId === match.subscriptionId && this.#subscription.openOccurrenceCount(match.subscriptionId) !== baselineOpen) {
+        this.#logger.info(`anpr-bridge: ${match.subscriptionId} already transacted — skipping ANPR emit`);
+        return;
+      }
+
       // Plate-level debounce — belt-and-suspenders against a gap that slips the
       // camera-level gate re-emitting the SAME plate.
       const plateKey = `${deviceId}:${plate}`;

apps/server/src/subscription-flow.ts

@@ -310,6 +310,15 @@ export class SubscriptionFlow {
    * subscription, (b) pick which occurrence a read closes, and (c) enforce
    * `maxConcurrent`. The on-chain field is `permitId`, so we match against that.
    */
+  /** How many occurrences this subscription currently has OPEN (entries not yet exited).
+   *  Public so the ANPR bridge can detect a credential (card/QR) exit landing mid-poll — if
+   *  the count drops while it's polling, the subscriber already transacted and the bridge must
+   *  NOT also emit (which would exit the NEXT open occurrence — a phantom double-exit, esp. for
+   *  a fleet sub). See anpr-entry.ts. */
+  openOccurrenceCount(subscriptionId: string): number {
+    return this.#openOccurrences(subscriptionId).length;
+  }
+
   #openOccurrences(subscriptionId: string): { identity: string; index: number }[] {
     const rows = this.#db.select().from(ledgerEvents).orderBy(ledgerEvents.index).all();
     // Net entries−exits per occurrence identity, keeping the entry order (oldest first).