v0.1.5: detect free windows in the estimate fallback + add API tests

App:
- When the single-estimate fallback sees MaxTime 0 (or an all-$0.00 ladder),
  show "Parking is currently free" instead of a bogus $0.00 purchase ladder.
  Free-detection extracted to tested client helpers (isFreeEstimate/ladderAllFree).

Client + tests (node:test, zero deps):
- src/estimates.ts: pure isFreeEstimate/ladderAllFree helpers (exported).
- test/estimates + test/http (mocked fetch): headers, query serialization,
  error->ParkSmarterApiError, rolling Auth_Token refresh, 401 clears token.
- test/integration: live checks against the Sandpoint (DSB) zones; targets the
  `test` instance by default and SKIPS when it's unreachable (non-prod is
  IP-restricted -> 403). Verified 3/3 green against prodv2 read-only.
- CI runs `npm test` as a build gate.

Note: dev/stage/test instances return 403 "Web App - Unavailable" from the
public internet (IP-restricted). API schema is otherwise unchanged vs Jul 6.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/app.json

@@ -3,14 +3,14 @@
     "name": "BigBrainParking",
     "slug": "bigbrainparking",
     "scheme": "bigbrainparking",
-    "version": "0.1.4",
+    "version": "0.1.5",
     "orientation": "portrait",
     "userInterfaceStyle": "automatic",
     "newArchEnabled": true,
     "icon": "./assets/icon.png",
     "android": {
       "package": "top.mowden.bigbrainparking",
-      "versionCode": 4,
+      "versionCode": 5,
       "edgeToEdgeEnabled": true,
       "adaptiveIcon": {
         "foregroundImage": "./assets/adaptive-icon.png",

app/src/screens/StartSessionScreen.tsx

@@ -17,10 +17,12 @@ import { useTheme } from '@/theme/ThemeContext';
 import { scheduleExpiryReminder } from '@/notifications/localReminders';
 import { logLine } from '@/features/diagnostics/fileLogger';
 import type { RootStackParamList } from '@/navigation/RootNavigator';
-import type {
-  CreditCardDetail,
-  ParkingDetail,
-  VehicleDetail,
+import {
+  isFreeEstimate,
+  ladderAllFree,
+  type CreditCardDetail,
+  type ParkingDetail,
+  type VehicleDetail,
 } from 'parksmarter-client';
 
 type SessionRoute = RouteProp<RootStackParamList, 'StartSession'>;
@@ -40,16 +42,26 @@ const money = (v?: string | number) => `$${Number(v ?? 0).toFixed(2)}`;
  * works. Build a price ladder from ParkingEstimate (single) across the zone's
  * Min/Max time so those zones stay purchasable instead of showing a blank screen.
  */
-async function buildSingleLadder(base: {
+export interface SingleLadderResult {
+  /** MaxTime 0 / all-$0.00 => currently free; show the free banner, not a ladder. */
+  free: boolean;
+  ladder: ParkingDetail[];
+}
+
+export async function buildSingleLadder(base: {
   zoneId: number;
   spaceId: number;
   customerId: number;
   vehicleId: number;
-}): Promise<ParkingDetail[]> {
+}): Promise<SingleLadderResult> {
   const probe = await ps.getParkingEstimateSingle({ ...base, durationInMinutes: 30, creditCardId: 0 });
   if ((probe as any)?.Response?.Status === 'Error') {
     throw new Error((probe as any).Response?.Message || 'Estimate unavailable for this space.');
   }
+  // MaxTime 0 means no paid time is available right now — this is a free window,
+  // not a purchasable zone. Don't build a bogus $0.00 ladder.
+  if (isFreeEstimate(probe)) return { free: true, ladder: [] };
+
   const min = Math.max(5, Number(probe.MinTime) || 5);
   const max = Math.max(min, Number(probe.MaxTime) || min);
   const span = max - min;
@@ -70,7 +82,10 @@ async function buildSingleLadder(base: {
       }
     }),
   );
-  return rungs.filter((r): r is ParkingDetail => r != null);
+  const ladder = rungs.filter((r): r is ParkingDetail => r != null);
+  // If every rung came back $0.00, it's effectively a free window too.
+  if (ladderAllFree(ladder)) return { free: true, ladder: [] };
+  return { free: false, ladder };
 }
 
 /** Parse the API's "MM-DD-YYYY hh:mm AM" end-time string into a Date for reminders. */
@@ -107,6 +122,8 @@ export function StartSessionScreen() {
   const [loading, setLoading] = useState(true);
   const [paying, setPaying] = useState(false);
   const [ladderError, setLadderError] = useState<string | null>(null);
+  // Free detected from the estimate (MaxTime 0 / $0.00) rather than the policy.
+  const [estimatedFree, setEstimatedFree] = useState(false);
 
   // Load the account's vehicles + cards and pick the defaults.
   useEffect(() => {
@@ -129,6 +146,7 @@ export function StartSessionScreen() {
     if (vehicleId == null || space?.SpaceId == null) return;
     setLoading(true);
     setLadderError(null);
+    setEstimatedFree(false);
     const base = {
       zoneId: zone.ZoneId!,
       spaceId: space.SpaceId!,
@@ -151,7 +169,13 @@ export function StartSessionScreen() {
           `[ESTIMATE] multi ${multiErrored ? 'errored' : 'empty'} for zone=${base.zoneId} ` +
             `space=${base.spaceId}; falling back to single`,
         );
-        details = await buildSingleLadder(base);
+        const fb = await buildSingleLadder(base);
+        if (fb.free) {
+          logLine(`[ESTIMATE] zone=${base.zoneId} is currently free (MaxTime 0)`);
+          setEstimatedFree(true);
+          return;
+        }
+        details = fb.ladder;
       }
       if (!details.length) {
         throw new Error('No parking options are available for this space right now.');
@@ -283,6 +307,22 @@ export function StartSessionScreen() {
     );
   }
 
+  if (estimatedFree) {
+    return (
+      <View style={[styles.center, { backgroundColor: colors.bg, padding: 24 }]}>
+        <Text style={[styles.zone, { color: colors.text }]}>{zone.ZoneName}</Text>
+        <View style={[styles.freeBanner, { backgroundColor: '#e8f5e9', marginTop: 16, alignSelf: 'stretch' }]}>
+          <Text style={{ color: '#2e7d32', fontWeight: '700', fontSize: 16 }}>
+            Parking is currently free
+          </Text>
+          <Text style={{ color: colors.subtext, marginTop: 6 }}>
+            No payment needed right now — just park.
+          </Text>
+        </View>
+      </View>
+    );
+  }
+
   if (ladderError && !ladder.length) {
     return (
       <View style={[styles.center, { backgroundColor: colors.bg, padding: 24 }]}>