Delivery Route Planner

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399

<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="color-scheme" content="light dark">
<title>Delivery Route Planner</title>
<style>
/* sloprun design tokens — inline this block into every demo (self-contained rule).
   Identity: instrument-panel. Machine facts in mono; human words in sans.
   Green is EARNED: only for "it ran / it worked" states, never decoration. */
:root {
  --bg: #F6F6F3;          /* neutral paper, not cream */
  --surface: #FFFFFF;
  --ink: #1A1D21;
  --muted: #5A6068;
  --line: #E3E2DC;
  --accent: #C05600;      /* phosphor amber, darkened for light bg */
  --accent-soft: #FFF3E6;
  --run: #1A7F37;         /* earned green */
  --run-soft: #E7F4EA;
  --danger: #C93C37;
  --radius: 10px;
  --font-sans: system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Code", Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #14161A; --surface: #1C1F26; --ink: #E8E6E1; --muted: #9AA0A8;
    --line: #2A2E36; --accent: #FFB454; --accent-soft: #2A2118;
    --run: #3FB950; --run-soft: #16281B; --danger: #F47067;
  }
}
:root[data-theme="dark"] {
  --bg: #14161A; --surface: #1C1F26; --ink: #E8E6E1; --muted: #9AA0A8;
  --line: #2A2E36; --accent: #FFB454; --accent-soft: #2A2118;
  --run: #3FB950; --run-soft: #16281B; --danger: #F47067;
}
body { background: var(--bg); color: var(--ink); font-family: var(--font-sans); }
:root[data-theme="light"] { color-scheme: light; }
:root[data-theme="dark"]  { color-scheme: dark; }

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  line-height: 1.5;
  overflow-x: hidden;
  -webkit-text-size-adjust: 100%;
  font-size: 15px;
}
.wrap { max-width: 1180px; margin: 0 auto; padding: 18px 14px 32px; }
h1, h2, h3 { margin: 0; font-weight: 600; letter-spacing: -0.01em; }
.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
.sr {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }

/* ---------- header ---------- */
.head {
  display: flex; flex-wrap: wrap; gap: 12px 16px;
  align-items: flex-start; justify-content: space-between;
  padding-bottom: 14px; margin-bottom: 14px;
  border-bottom: 1px solid var(--line);
}
.head h1 { font-size: 1.32rem; }
.lede { margin: 5px 0 0; color: var(--muted); max-width: 64ch; font-size: 0.95rem; }
.status {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--font-mono); font-size: 0.74rem; letter-spacing: 0.02em;
  padding: 6px 10px; border: 1px solid var(--line); border-radius: 999px;
  background: var(--surface); color: var(--muted); white-space: nowrap;
  flex-shrink: 0;
}
.status .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--muted); flex: none; }
.status[data-state="load"] .dot { background: var(--accent); animation: pulse 1.1s ease-in-out infinite; }
.status[data-state="ok"] .dot { background: var(--run); }
.status[data-state="ok"] { color: var(--run); border-color: var(--run); background: var(--run-soft); }
.status[data-state="warn"] .dot { background: var(--accent); }
.status[data-state="warn"] { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }
@keyframes pulse { 0%,100% { opacity: 1; } 50% { opacity: 0.25; } }

/* ---------- layout ---------- */
.grid { display: grid; gap: 14px; grid-template-columns: 306px minmax(0, 1fr); align-items: start; }
.col { display: grid; gap: 14px; min-width: 0; }
@media (max-width: 900px) {
  .grid { grid-template-columns: minmax(0, 1fr); }
  .controls { order: 2; }
  .col { order: 1; }
}
.panel {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 14px; min-width: 0;
}
.panel > h2, .map-head h2 {
  font-family: var(--font-mono); font-size: 0.7rem; text-transform: uppercase;
  letter-spacing: 0.09em; color: var(--muted); font-weight: 600; margin-bottom: 12px;
}

/* ---------- controls ---------- */
.presets { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 16px; }
button {
  font: inherit; color: var(--ink); background: var(--surface);
  border: 1px solid var(--line); border-radius: 7px;
  padding: 7px 11px; min-height: 34px; cursor: pointer;
  font-family: var(--font-mono); font-size: 0.75rem;
  transition: background 0.12s ease, border-color 0.12s ease, color 0.12s ease;
}
button:hover { border-color: var(--accent); color: var(--accent); }
button[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }
.ctl { margin-bottom: 15px; }
.ctl:last-child { margin-bottom: 0; }
.ctl-top { display: flex; justify-content: space-between; align-items: baseline; gap: 10px; margin-bottom: 4px; }
.ctl-top label { font-size: 0.88rem; }
.ctl-val {
  font-family: var(--font-mono); font-variant-numeric: tabular-nums;
  font-size: 0.88rem; font-weight: 600; color: var(--accent); white-space: nowrap;
}
.ctl-hint { font-family: var(--font-mono); font-size: 0.68rem; color: var(--muted); margin-top: 3px; }
.ctl-hint.bad { color: var(--danger); }
input[type=range] {
  -webkit-appearance: none; appearance: none;
  width: 100%; height: 24px; background: transparent; margin: 0; display: block; cursor: pointer;
}
input[type=range]::-webkit-slider-runnable-track { height: 4px; background: var(--line); border-radius: 2px; }
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none; width: 16px; height: 16px; margin-top: -6px; border-radius: 50%;
  background: var(--accent); border: 2px solid var(--surface); box-shadow: 0 0 0 1px var(--line);
}
input[type=range]::-moz-range-track { height: 4px; background: var(--line); border-radius: 2px; }
input[type=range]::-moz-range-thumb {
  width: 16px; height: 16px; border-radius: 50%;
  background: var(--accent); border: 2px solid var(--surface); box-shadow: 0 0 0 1px var(--line);
}
input[type=range]:focus-visible { outline: none; }
input[type=range]:focus-visible::-webkit-slider-thumb { box-shadow: 0 0 0 3px var(--bg), 0 0 0 5px var(--accent); }
input[type=range]:focus-visible::-moz-range-thumb { box-shadow: 0 0 0 3px var(--bg), 0 0 0 5px var(--accent); }
.ends { display: flex; justify-content: space-between; font-family: var(--font-mono); font-size: 0.66rem; color: var(--muted); }
.btnrow { display: flex; gap: 6px; flex-wrap: wrap; }
.tip {
  margin: 14px 0 0; padding: 9px 10px; border: 1px dashed var(--line); border-radius: 8px;
  background: var(--bg); color: var(--muted); font-size: 0.8rem;
}
.tip b { color: var(--ink); font-weight: 600; }

/* ---------- stats ---------- */
.stats {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(136px, 1fr)); gap: 1px;
  background: var(--line); border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; margin: 0;
}
.stat { background: var(--surface); padding: 11px 12px; min-width: 0; }
.stat dt {
  font-family: var(--font-mono); font-size: 0.63rem; text-transform: uppercase;
  letter-spacing: 0.07em; color: var(--muted); margin-bottom: 3px;
}
.stat dd {
  margin: 0; font-family: var(--font-mono); font-variant-numeric: tabular-nums;
  font-size: 1.18rem; font-weight: 600; letter-spacing: -0.02em;
}
.stat dd small { font-size: 0.62rem; font-weight: 400; color: var(--muted); display: block; letter-spacing: 0.03em; margin-top: 2px; }
.stat dd .u { font-size: 0.7rem; font-weight: 500; color: var(--muted); margin-left: 2px; }
.stat[data-tone="good"] dd .n { color: var(--run); }
.stat[data-tone="warn"] dd .n { color: var(--accent); }

/* ---------- map ---------- */
.map-head { display: flex; flex-wrap: wrap; gap: 8px 12px; align-items: center; justify-content: space-between; margin-bottom: 10px; }
.map-head h2 { margin: 0; }
.pass {
  font-family: var(--font-mono); font-size: 0.68rem; color: var(--muted);
  font-variant-numeric: tabular-nums; white-space: nowrap;
}
.pass b { color: var(--accent); font-weight: 600; }
.map-box { position: relative; }
canvas {
  display: block; width: 100%; height: 300px;
  border: 1px solid var(--line); border-radius: 8px; touch-action: manipulation; cursor: crosshair;
}
canvas:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.readout {
  margin-top: 9px; padding: 8px 10px; border: 1px solid var(--line); border-radius: 7px;
  background: var(--bg); font-family: var(--font-mono); font-size: 0.72rem;
  font-variant-numeric: tabular-nums; color: var(--muted);
  min-height: 34px; display: flex; align-items: center; gap: 4px 12px; flex-wrap: wrap;
}
.readout b { color: var(--ink); font-weight: 600; }
.readout .hl { color: var(--accent); font-weight: 600; }

/* ---------- trips ---------- */
.trips { margin-top: 12px; display: grid; gap: 8px; }
.trip { border: 1px solid var(--line); border-radius: 8px; padding: 8px 10px; background: var(--bg); }
.trip-top {
  display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
  font-family: var(--font-mono); font-size: 0.72rem; font-variant-numeric: tabular-nums;
}
.trip-top .sw { width: 10px; height: 10px; border-radius: 3px; flex: none; }
.trip-top .nm { font-weight: 600; letter-spacing: 0.04em; }
.trip-top .sp { flex: 1 1 auto; }
.trip-top .dim { color: var(--muted); }
.bar { margin-top: 6px; height: 5px; border-radius: 3px; background: var(--line); overflow: hidden; }
.bar i { display: block; height: 100%; border-radius: 3px; transition: width 0.3s ease; }
.warnrow {
  border: 1px solid var(--danger); border-radius: 8px; padding: 8px 10px;
  color: var(--danger); font-size: 0.8rem; display: none;
}
.warnrow.show { display: block; }
.warnrow b { font-family: var(--font-mono); font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.06em; }
.warnrow p { margin: 2px 0 0; color: var(--muted); }
.note { margin: 11px 0 0; font-family: var(--font-mono); font-size: 0.66rem; color: var(--muted); line-height: 1.65; }

/* ---------- footer ---------- */
.foot {
  margin-top: 20px; padding-top: 12px; border-top: 1px solid var(--line);
  font-family: var(--font-mono); font-size: 0.7rem; color: var(--muted);
  display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important; animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}
@media (max-width: 560px) {
  .pass { white-space: normal; }
}
@media (max-width: 420px) {
  .wrap { padding: 14px 11px 26px; }
  .head h1 { font-size: 1.15rem; }
  .stat dd { font-size: 1.05rem; }
}
</style>
</head>
<body>
<div class="wrap">

  <header class="head">
    <div>
      <h1>Delivery Route Planner</h1>
      <p class="lede">A small electric delivery van leaves the depot, drops parcels around the neighbourhood, and comes home. This finds the shortest way round — and breaks the run into separate trips when one battery charge won't cover the lot.</p>
    </div>
    <div class="status" id="status" data-state="load">
      <span class="dot" aria-hidden="true"></span>
      <span id="statusText">planning…</span>
    </div>
  </header>

  <main class="grid">

    <section class="panel controls" aria-labelledby="ctlH">
      <h2 id="ctlH">Set-up</h2>

      <div class="presets" role="group" aria-label="Example neighbourhoods">
        <button type="button" data-preset="spread" aria-pressed="true">suburban spread</button>
        <button type="button" data-preset="two" aria-pressed="false">two estates</button>
        <button type="button" data-preset="block" aria-pressed="false">dense block</button>
      </div>

      <div class="ctl">
        <div class="ctl-top">
          <label for="rng">Battery range</label>
          <span class="ctl-val" id="v-rng">14.0 km</span>
        </div>
        <input type="range" id="rng" min="40" max="400" step="5" value="140"
               aria-describedby="h-rng">
        <div class="ends" aria-hidden="true"><span>4 km</span><span>40 km</span></div>
        <div class="ctl-hint" id="h-rng">one charge, out and back — reaches 7.0 km from the depot</div>
      </div>

      <div class="ctl">
        <div class="ctl-top">
          <span>Parcels on the round</span>
          <span class="ctl-val" id="v-drops">12</span>
        </div>
        <div class="btnrow" style="margin-top:4px">
          <button type="button" id="btn-opt">re-plan</button>
          <button type="button" id="btn-shuffle">shuffle</button>
          <button type="button" id="btn-reset">reset</button>
        </div>
      </div>

      <div class="ctl">
        <div class="btnrow">
          <button type="button" id="btn-ghost" aria-pressed="false">show first guess</button>
          <button type="button" id="btn-reach" aria-pressed="true">show range ring</button>
        </div>
      </div>

      <p class="tip">
        <b>Click the map</b> to drop a parcel anywhere, or click an existing drop to cancel it.
        The route re-plans itself every time.
      </p>
    </section>

    <div class="col">

      <dl class="stats">
        <div class="stat" id="st-dist">
          <dt>Total distance</dt>
          <dd><span class="n" id="s-dist">—</span><span class="u">km</span><small>every trip, out and back</small></dd>
        </div>
        <div class="stat" id="st-trips">
          <dt>Trips needed</dt>
          <dd><span class="n" id="s-trips">—</span><small id="s-trips-sub">one battery charge each</small></dd>
        </div>
        <div class="stat" id="st-imp">
          <dt>Shorter than first guess</dt>
          <dd><span class="n" id="s-imp">—</span><span class="u" id="s-imp-u">%</span><small id="s-imp-sub">vs. nearest drop each time</small></dd>
        </div>
        <div class="stat" id="st-long">
          <dt>Longest trip</dt>
          <dd><span class="n" id="s-long">—</span><span class="u">km</span><small id="s-long-sub">of the 14.0 km range</small></dd>
        </div>
      </dl>

      <section class="panel" aria-labelledby="mapH">
        <div class="map-head">
          <h2 id="mapH">Route map · 1 square = 1 km</h2>
          <span class="pass mono" id="pass">nearest drop each time…</span>
        </div>

        <div class="map-box">
          <canvas id="map" tabindex="0"
            aria-label="Map of the depot and parcel drops. Move the crosshair with the arrow keys and press Enter to add or remove a drop there.">
            <p id="cvAlt">Route map. The depot sits in the middle of the map; parcel drops are scattered around it.</p>
          </canvas>
        </div>

        <div class="readout" id="readout">Click anywhere on the map to add a drop — or click a drop to cancel it.</div>

        <div class="trips" id="trips"></div>

        <div class="warnrow" id="warn" role="status">
          <b id="warnTitle">out of range</b>
          <p id="warnBody"></p>
        </div>

        <p class="note" id="note"></p>
        <p class="sr" id="live" role="status" aria-live="polite"></p>
      </section>

    </div>
  </main>

  <footer class="foot">
    <span>demo · sloprun.dev</span>
    <span id="perf">—</span>
  </footer>
</div>

<script>
(function () {
  "use strict";

  var $ = function (id) { return document.getElementById(id); };
  var now = function () {
    return (window.performance && performance.now) ? performance.now() : Date.now();
  };

  /* ------------------------------------------------------------------ *
   * Map geometry. Everything internal is in "map units".
   * 10 map units = 1 km, so the visible grid squares are 1 km across.
   * ------------------------------------------------------------------ */
  var MW = 100, MH = 68;          // map size in units
  var DEPOT = { x: 50, y: 35 };
  var MAXD = 26;                  // most drops we will plan for
  var HIT = 4.2;                  // click tolerance, in units
  var MONO = 'ui-monospace, "SF Mono", Menlo, Consolas, monospace';

  var PRESETS = {
    spread: [[76,55],[26,14],[32,42],[49.5,23],[48,49],[86.5,22.5],[69,11],[12,8],[66.5,29.5],[18.5,58.5],[14.5,33],[76.5,38.5]],
    two:    [[14,16],[26,12],[20,28],[32,26],[12,34],[28,38],[38,18],
             [66,40],[78,34],[86,46],[74,52],[64,58],[84,60],[92,36]],
    block:  [[30,18],[42,16],[54,20],[66,18],[28,30],[40,28],[52,32],[64,30],
             [30,44],[42,46],[54,42],[66,48],[34,56],[46,58],[58,56],[72,58]]
  };

  /* ------------------------------------------------------------------ *
   * State
   * ------------------------------------------------------------------ */
  var drops = [];                 // [{x,y}] in map units
  var RU = 140;                   // battery range, in map units (= 14.0 km)
  var S = null;                   // current solution bundle
  var _best = null, _prev = null; // scratch arrays for the split DP

  var phase = "idle";             // idle | build | opt | done
  var raf = null, nextT = 0, buildK = 0, flash = null, optT0 = 0, solveMs = 0;
  var ghostOn = false, reachOn = true, scan = null, recut = false;
  var hover = -1, kb = false, cur = { x: 50, y: 16 };

  /* ------------------------------------------------------------------ *
   * Distance helpers
   * ------------------------------------------------------------------ */
  function dist(a, b) { return Math.sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y)); }
  function km(u) { return u / 10; }
  function f2(u) { return km(u).toFixed(2); }
  function f1(u) { return km(u).toFixed(1); }

  /* ------------------------------------------------------------------ *
   * prep — split drops into reachable / out-of-range, build distance table
   * ------------------------------------------------------------------ */
  function prep() {
    var pts = [], far = [], i, j;
    for (i = 0; i < drops.length; i++) {
      if (2 * dist(drops[i], DEPOT) <= RU + 1e-9) pts.push(drops[i]);
      else far.push(drops[i]);
    }
    var n = pts.length;
    var D = new Float64Array(n * n), Dd = new Float64Array(n);
    for (i = 0; i < n; i++) {
      Dd[i] = dist(pts[i], DEPOT);
      for (j = i + 1; j < n; j++) {
        var d = dist(pts[i], pts[j]);
        D[i * n + j] = d; D[j * n + i] = d;
      }
    }
    S = {
      pts: pts, far: far, D: D, Ddep: Dd, n: n,
      order: [], trips: [], of: [], cost: 0,
      naiveCost: 0, naiveTrips: [], moves: 0
    };
    _best = new Float64Array(n + 1);
    _prev = new Int32Array(n + 1);
  }

  /* nearest-drop-each-time construction — the "first guess" */
  function nearestFirst() {
    var n = S.n, used = new Uint8Array(n), ord = [], cur2 = -1, k, i;
    for (k = 0; k < n; k++) {
      var b = -1, bd = Infinity;
      for (i = 0; i < n; i++) {
        if (used[i]) continue;
        var d = cur2 < 0 ? S.Ddep[i] : S.D[cur2 * n + i];
        if (d < bd) { bd = d; b = i; }
      }
      used[b] = 1; ord.push(b); cur2 = b;
    }
    return ord;
  }

  /* ------------------------------------------------------------------ *
   * split — cut a visiting order into battery-sized round trips.
   * Exact dynamic program: best[j] = cheapest way to serve the first j
   * drops of the order, where every trip starts and ends at the depot
   * and never exceeds the battery range.
   * ------------------------------------------------------------------ */
  function splitCost(ord) {
    var n = ord.length, D = S.D, Dd = S.Ddep, b = _best, j, i;
    if (!n) return 0;
    b[0] = 0;
    for (j = 1; j <= n; j++) {
      var bestJ = Infinity, inner = 0, last = Dd[ord[j - 1]];
      for (i = j - 1; i >= 0; i--) {
        if (i < j - 1) inner += D[ord[i] * n + ord[i + 1]];
        var len = Dd[ord[i]] + inner + last;
        if (len <= RU + 1e-9) {
          var c = b[i] + len;
          if (c < bestJ) bestJ = c;
        }
      }
      b[j] = bestJ;
    }
    return b[n];
  }

  function splitTrips(ord) {
    var n = ord.length, D = S.D, Dd = S.Ddep, b = _best, p = _prev, j, i;
    if (!n) return { cost: 0, trips: [] };
    b[0] = 0; p[0] = -1;
    for (j = 1; j <= n; j++) {
      var bestJ = Infinity, from = -1, inner = 0, last = Dd[ord[j - 1]];
      for (i = j - 1; i >= 0; i--) {
        if (i < j - 1) inner += D[ord[i] * n + ord[i + 1]];
        var len = Dd[ord[i]] + inner + last;
        if (len <= RU + 1e-9) {
          var c = b[i] + len;
          if (c < bestJ) { bestJ = c; from = i; }
        }
      }
      b[j] = bestJ; p[j] = from;
    }
    var trips = [], j2 = n, guard = 0;
    while (j2 > 0 && guard++ < n + 2) {
      var i2 = p[j2];
      if (i2 < 0) { i2 = j2 - 1; }           /* defensive: never loop forever */
      trips.push(ord.slice(i2, j2));
      j2 = i2;
    }
    trips.reverse();
    return { cost: b[n], trips: trips };
  }

  /* The "first guess" a person would make: hop to the nearest parcel, and
     turn for home the moment the next one would not fit on the charge. */
  function greedySplit(ord) {
    var trips = [], cur = [], cost = 0, k;
    for (k = 0; k < ord.length; k++) {
      var trial = cur.concat([ord[k]]);
      if (tripLen(trial) <= RU + 1e-9) { cur = trial; }
      else {
        if (cur.length) { trips.push(cur); cost += tripLen(cur); }
        cur = [ord[k]];
      }
    }
    if (cur.length) { trips.push(cur); cost += tripLen(cur); }
    return { cost: cost, trips: trips };
  }

  function tripLen(t) {
    if (!t.length) return 0;
    var n = S.n, L = S.Ddep[t[0]] + S.Ddep[t[t.length - 1]];
    for (var i = 0; i + 1 < t.length; i++) L += S.D[t[i] * n + t[i + 1]];
    return L;
  }

  /* ------------------------------------------------------------------ *
   * 2-opt: reverse the stretch between two legs, keep it if shorter.
   * The score is the *split* distance, so a swap only counts as an
   * improvement when the whole multi-trip plan gets shorter.
   * ------------------------------------------------------------------ */
  function rev(a, i, j) {
    while (i < j) { var t = a[i]; a[i] = a[j]; a[j] = t; i++; j--; }
  }

  function bestMove() {
    var ord = S.order, n = ord.length, bi = -1, bj = -1, bc = S.cost - 1e-7, i, j;
    for (i = 0; i < n - 1; i++) {
      for (j = i + 1; j < n; j++) {
        rev(ord, i, j);
        var c = splitCost(ord);
        if (c < bc) { bc = c; bi = i; bj = j; }
        rev(ord, i, j);
      }
    }
    return bi < 0 ? null : { i: bi, j: bj, cost: bc };
  }

  function indexTrips() {
    S.of = new Array(S.n);
    for (var k = 0; k < S.trips.length; k++) {
      for (var m = 0; m < S.trips[k].length; m++) S.of[S.trips[k][m]] = { t: k, seq: m + 1 };
    }
  }

  /* ------------------------------------------------------------------ *
   * Colours — re-read from the tokens whenever the theme moves
   * ------------------------------------------------------------------ */
  var LIGHTP = ["#C05600", "#2C6BC7", "#7A4BC4", "#B5379E", "#0B6C75", "#7E6100"];
  var DARKP  = ["#FFB454", "#6EA8FF", "#B48CFF", "#FF8BD6", "#4FD3DE", "#D9BB5A"];
  var C = {};

  function cssv(v) {
    return getComputedStyle(document.documentElement).getPropertyValue(v).trim();
  }
  function rgb(h) {
    h = (h || "").replace("#", "");
    if (h.length === 3) h = h[0] + h[0] + h[1] + h[1] + h[2] + h[2];
    var n = parseInt(h, 16);
    if (isNaN(n)) return [128, 128, 128];
    return [(n >> 16) & 255, (n >> 8) & 255, n & 255];
  }
  function rgba(h, a) { var c = rgb(h); return "rgba(" + c[0] + "," + c[1] + "," + c[2] + "," + a + ")"; }
  function colors() {
    C.bg = cssv("--bg") || "#F6F6F3";
    C.ink = cssv("--ink") || "#1A1D21";
    C.muted = cssv("--muted") || "#5A6068";
    C.line = cssv("--line") || "#E3E2DC";
    C.accent = cssv("--accent") || "#C05600";
    C.danger = cssv("--danger") || "#C93C37";
    var c = rgb(C.bg);
    C.dark = (0.299 * c[0] + 0.587 * c[1] + 0.114 * c[2]) / 255 < 0.45;
    C.trip = C.dark ? DARKP : LIGHTP;
  }
  function tripColor(k) { return C.trip[k % C.trip.length]; }

  /* ------------------------------------------------------------------ *
   * Canvas
   * ------------------------------------------------------------------ */
  var cv = $("map"), ctx = cv.getContext("2d");
  var dpr = 1, VW = 0, VH = 0, sc = 1, ox = 0, oy = 0;

  function layout() {
    var w = Math.max(240, cv.parentNode.clientWidth || 320);
    var h = Math.round(Math.min(430, Math.max(210, w * 0.64)));
    var d = Math.min(2, window.devicePixelRatio || 1);
    /* Writing cv.style.height resizes our own observed box, so a no-op resize
       must bail out here or the ResizeObserver re-enters on every frame. */
    if (w === VW && h === VH && d === dpr) return false;
    dpr = d;
    cv.style.height = h + "px";
    cv.width = Math.round(w * dpr);
    cv.height = Math.round(h * dpr);
    VW = w; VH = h;
    var pad = 15;
    sc = Math.min((w - 2 * pad) / MW, (h - 2 * pad) / MH);
    ox = (w - MW * sc) / 2; oy = (h - MH * sc) / 2;
    return true;
  }
  function tx(x) { return ox + x * sc; }
  function ty(y) { return oy + y * sc; }
  function inv(px, py) { return { x: (px - ox) / sc, y: (py - oy) / sc }; }

  function drawGrid() {
    var x, y, L = tx(0), R = tx(MW), T = ty(0), B = ty(MH);
    ctx.lineWidth = 1;
    for (x = 0; x <= MW; x += 5) {
      ctx.strokeStyle = (x % 10 === 0) ? rgba(C.line, 0.95) : rgba(C.line, 0.45);
      var px = Math.round(tx(x)) + 0.5;
      ctx.beginPath(); ctx.moveTo(px, T); ctx.lineTo(px, B); ctx.stroke();
    }
    for (y = 0; y <= MH; y += 5) {
      ctx.strokeStyle = (y % 10 === 0) ? rgba(C.line, 0.95) : rgba(C.line, 0.45);
      var py = Math.round(ty(y)) + 0.5;
      ctx.beginPath(); ctx.moveTo(L, py); ctx.lineTo(R, py); ctx.stroke();
    }
  }

  /* How far the far corner of the map is from the depot. Past this the reach
     ring is off the map entirely, so a circle would draw nothing at all. */
  var CORNER = (function () {
    var c = [[0, 0], [MW, 0], [0, MH], [MW, MH]], m = 0;
    for (var i = 0; i < c.length; i++) m = Math.max(m, dist({ x: c[i][0], y: c[i][1] }, DEPOT));
    return m;
  })();

  function drawRing() {
    if (!reachOn) return;
    var reach = RU / 2;
    ctx.save();
    if (reach >= CORNER) {
      /* The ring is wider than the whole map — say so instead of drawing
         an invisible circle, so the toggle never looks dead. */
      var lx = tx(0) + 8, ly = ty(0) + 7;
      ctx.setLineDash([3, 3]);
      ctx.lineWidth = 1.2;
      ctx.strokeStyle = rgba(C.muted, 0.6);
      ctx.beginPath(); ctx.arc(lx + 5, ly + 6, 5, 0, 6.2832); ctx.stroke();
      ctx.setLineDash([]);
      ctx.font = "600 10px " + MONO;
      ctx.textAlign = "left"; ctx.textBaseline = "middle";
      ctx.fillStyle = rgba(C.muted, 0.95);
      ctx.fillText("reach " + f1(reach) + " km — the whole map is in range", lx + 15, ly + 6);
    } else {
      ctx.setLineDash([4, 5]);
      ctx.lineWidth = 1.2;
      ctx.strokeStyle = rgba(C.muted, 0.5);
      ctx.beginPath(); ctx.arc(tx(DEPOT.x), ty(DEPOT.y), reach * sc, 0, 6.2832); ctx.stroke();
    }
    ctx.restore();
  }

  function arrow(ax, ay, bx, by, col) {
    var dx = bx - ax, dy = by - ay, L = Math.sqrt(dx * dx + dy * dy);
    if (L < 30) return;
    var mx = ax + dx * 0.56, my = ay + dy * 0.56, an = Math.atan2(dy, dx), s = 4.6;
    ctx.beginPath();
    ctx.moveTo(mx + Math.cos(an) * s, my + Math.sin(an) * s);
    ctx.lineTo(mx + Math.cos(an + 2.5) * s, my + Math.sin(an + 2.5) * s);
    ctx.lineTo(mx + Math.cos(an - 2.5) * s, my + Math.sin(an - 2.5) * s);
    ctx.closePath();
    ctx.fillStyle = col; ctx.fill();
  }

  function path(idxs, w, col, dash, arrows) {
    if (!idxs.length) return;
    var i, ax = tx(DEPOT.x), ay = ty(DEPOT.y);
    ctx.save();
    if (dash) ctx.setLineDash(dash);
    ctx.lineWidth = w; ctx.lineJoin = "round"; ctx.lineCap = "round";
    ctx.strokeStyle = col;
    ctx.beginPath(); ctx.moveTo(ax, ay);
    for (i = 0; i < idxs.length; i++) ctx.lineTo(tx(S.pts[idxs[i]].x), ty(S.pts[idxs[i]].y));
    ctx.lineTo(ax, ay);
    ctx.stroke();
    ctx.restore();
    if (!arrows) return;
    var px = ax, py = ay;
    for (i = 0; i < idxs.length; i++) {
      var qx = tx(S.pts[idxs[i]].x), qy = ty(S.pts[idxs[i]].y);
      arrow(px, py, qx, qy, col); px = qx; py = qy;
    }
    arrow(px, py, ax, ay, col);
  }

  function drawRoutes() {
    for (var k = 0; k < S.trips.length; k++) {
      path(S.trips[k], 2.3, tripColor(k), null, true);
    }
  }

  function drawGhost() {
    if (!ghostOn || !S.naiveTrips.length) return;
    for (var k = 0; k < S.naiveTrips.length; k++) {
      path(S.naiveTrips[k], 1.4, rgba(C.muted, 0.55), [3, 4], false);
    }
  }

  function drawBuild() {
    var ord = S.order.slice(0, buildK);
    if (!ord.length) return;
    ctx.save();
    ctx.setLineDash([5, 4]);
    ctx.lineWidth = 1.8; ctx.lineJoin = "round"; ctx.lineCap = "round";
    ctx.strokeStyle = rgba(C.accent, 0.85);
    ctx.beginPath(); ctx.moveTo(tx(DEPOT.x), ty(DEPOT.y));
    for (var i = 0; i < ord.length; i++) ctx.lineTo(tx(S.pts[ord[i]].x), ty(S.pts[ord[i]].y));
    ctx.stroke();
    ctx.restore();
  }

  function drawProbe() {
    if (phase !== "opt" || !scan || scan.i >= S.n - 1) return;
    var i = scan.i, j = Math.min(scan.j, S.order.length - 1), k, p;
    ctx.save();
    ctx.setLineDash([2, 3]);
    ctx.lineWidth = 1.3;
    ctx.strokeStyle = rgba(C.ink, C.dark ? 0.55 : 0.42);
    ctx.beginPath();
    for (k = i; k <= j; k++) {
      p = S.pts[S.order[k]];
      if (k === i) ctx.moveTo(tx(p.x), ty(p.y)); else ctx.lineTo(tx(p.x), ty(p.y));
    }
    ctx.stroke();
    ctx.setLineDash([]);
    ctx.lineWidth = 1.4;
    ctx.strokeStyle = rgba(C.ink, 0.65);
    for (k = 0; k < 2; k++) {
      p = S.pts[S.order[k === 0 ? i : j]];
      ctx.beginPath(); ctx.arc(tx(p.x), ty(p.y), dropR() + 3.5, 0, 6.2832); ctx.stroke();
    }
    ctx.restore();
  }

  function drawFlash(ts) {
    if (!flash) return;
    var age = ts - flash.t;
    if (age > 340) { flash = null; return; }
    var a = 0.34 * (1 - age / 340), i;
    ctx.save();
    ctx.lineWidth = 9; ctx.lineJoin = "round"; ctx.lineCap = "round";
    ctx.strokeStyle = rgba(C.accent, a);
    ctx.beginPath();
    for (i = flash.i; i <= flash.j && i < S.order.length; i++) {
      var p = S.pts[S.order[i]];
      if (i === flash.i) ctx.moveTo(tx(p.x), ty(p.y)); else ctx.lineTo(tx(p.x), ty(p.y));
    }
    ctx.stroke();
    ctx.restore();
  }

  function dropR() { return Math.max(5, Math.min(8.5, sc * 1.3)); }

  function drawPoints() {
    var r = dropR(), i;
    /* out of range */
    for (i = 0; i < S.far.length; i++) {
      var fx = tx(S.far[i].x), fy = ty(S.far[i].y);
      ctx.save();
      ctx.setLineDash([2.5, 2.5]);
      ctx.lineWidth = 1.6; ctx.strokeStyle = C.danger;
      ctx.beginPath(); ctx.arc(fx, fy, r, 0, 6.2832); ctx.stroke();
      ctx.restore();
      ctx.beginPath();
      ctx.moveTo(fx - r * 0.4, fy - r * 0.4); ctx.lineTo(fx + r * 0.4, fy + r * 0.4);
      ctx.moveTo(fx + r * 0.4, fy - r * 0.4); ctx.lineTo(fx - r * 0.4, fy + r * 0.4);
      ctx.lineWidth = 1.5; ctx.strokeStyle = C.danger; ctx.stroke();
    }
    /* in range */
    for (i = 0; i < S.n; i++) {
      var p = S.pts[i], px = tx(p.x), py = ty(p.y);
      var meta = (phase === "build") ? null : (S.of ? S.of[i] : null);
      var col, seq = null;
      if (phase === "build") {
        var pos = S.order.indexOf(i);
        col = (pos >= 0 && pos < buildK) ? C.accent : rgba(C.muted, 0.55);
      } else if (meta) {
        col = tripColor(meta.t); seq = meta.seq;
      } else {
        col = rgba(C.muted, 0.55);
      }
      ctx.beginPath(); ctx.arc(px, py, r, 0, 6.2832);
      ctx.fillStyle = col; ctx.fill();
      ctx.lineWidth = 2; ctx.strokeStyle = C.bg; ctx.stroke();
      if (seq !== null && r >= 6.3) {
        ctx.fillStyle = C.bg;
        ctx.font = "600 " + Math.round(r * 1.05) + "px " + MONO;
        ctx.textAlign = "center"; ctx.textBaseline = "middle";
        ctx.fillText(String(seq), px, py + 0.5);
      }
      if (hover === i) {
        ctx.beginPath(); ctx.arc(px, py, r + 4.5, 0, 6.2832);
        ctx.lineWidth = 1.6; ctx.strokeStyle = C.accent; ctx.stroke();
      }
    }
  }

  function drawDepot() {
    var d = Math.max(7, Math.min(11, sc * 1.7));
    var px = tx(DEPOT.x), py = ty(DEPOT.y);
    ctx.beginPath();
    if (ctx.roundRect) { ctx.roundRect(px - d, py - d, d * 2, d * 2, 3); }
    else { ctx.rect(px - d, py - d, d * 2, d * 2); }
    ctx.fillStyle = C.accent; ctx.fill();
    ctx.lineWidth = 2; ctx.strokeStyle = C.bg; ctx.stroke();
    ctx.beginPath(); ctx.arc(px, py, d * 0.3, 0, 6.2832);
    ctx.fillStyle = C.bg; ctx.fill();
    ctx.font = "600 9px " + MONO;
    ctx.textAlign = "center"; ctx.textBaseline = "top";
    /* halo so the label stays readable where route legs run under it */
    ctx.lineWidth = 3; ctx.lineJoin = "round"; ctx.strokeStyle = C.bg;
    ctx.strokeText("DEPOT", px, py + d + 4);
    ctx.fillStyle = C.muted;
    ctx.fillText("DEPOT", px, py + d + 4);
  }

  function drawCursor() {
    if (!kb) return;
    var px = tx(cur.x), py = ty(cur.y);
    ctx.save();
    ctx.setLineDash([3, 4]); ctx.lineWidth = 1; ctx.strokeStyle = rgba(C.accent, 0.75);
    ctx.beginPath();
    ctx.moveTo(tx(0), py); ctx.lineTo(tx(MW), py);
    ctx.moveTo(px, ty(0)); ctx.lineTo(px, ty(MH));
    ctx.stroke();
    ctx.setLineDash([]);
    ctx.beginPath(); ctx.arc(px, py, 8, 0, 6.2832);
    ctx.lineWidth = 1.8; ctx.strokeStyle = C.accent; ctx.stroke();
    ctx.restore();
  }

  function draw(ts) {
    ts = ts || now();
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    ctx.clearRect(0, 0, VW, VH);
    ctx.fillStyle = C.bg;
    ctx.fillRect(0, 0, VW, VH);
    drawGrid();
    drawRing();
    if (!S) return;
    if (phase === "build") { drawBuild(); }
    else { drawGhost(); drawRoutes(); drawProbe(); drawFlash(ts); }
    drawPoints();
    drawDepot();
    drawCursor();
  }

  /* ------------------------------------------------------------------ *
   * Readouts
   * ------------------------------------------------------------------ */
  function setStatus(state, text) {
    $("status").setAttribute("data-state", state);
    $("statusText").textContent = text;
  }

  function paintStats() {
    var n = S.n, trips = S.trips.length;
    $("s-dist").textContent = n ? f2(S.cost) : "—";
    $("s-trips").textContent = n ? String(trips) : "—";
    $("s-trips-sub").textContent = !n ? "nothing to deliver"
      : trips === 1 ? "it all fits one charge"
      : "split by battery range";

    var imp = (S.naiveCost > 0) ? (S.naiveCost - S.cost) / S.naiveCost * 100 : 0;
    var impEl = $("s-imp"), impU = $("s-imp-u"), impSub = $("s-imp-sub"), impBox = $("st-imp");
    if (!n || S.naiveCost <= 0) {
      impEl.textContent = "—"; impU.textContent = ""; impSub.textContent = "no route yet";
      impBox.removeAttribute("data-tone");
    } else if (phase === "build" || (phase === "opt" && imp < 0.05)) {
      /* still mid-solve — do not claim the first guess was already best */
      impEl.textContent = "—"; impU.textContent = ""; impSub.textContent = "still untangling…";
      impBox.removeAttribute("data-tone");
    } else if (imp >= 0.05) {
      impEl.textContent = imp.toFixed(1); impU.textContent = "%";
      impSub.textContent = f2(S.naiveCost - S.cost) + " km saved";
      impBox.setAttribute("data-tone", "good");
    } else {
      impEl.textContent = "0.0"; impU.textContent = "%";
      impSub.textContent = "first guess was already best";
      impBox.removeAttribute("data-tone");
    }

    var longest = 0;
    for (var k = 0; k < S.trips.length; k++) longest = Math.max(longest, tripLen(S.trips[k]));
    $("s-long").textContent = n ? f2(longest) : "—";
    $("s-long-sub").textContent = "of the " + f1(RU) + " km range";
    $("st-long").setAttribute("data-tone", (n && longest > RU * 0.9) ? "warn" : "");

    $("v-drops").textContent = String(drops.length);
  }

  function paintTrips() {
    paintWarn();
    var el = $("trips"), html = "", k;
    if (!S.n) {
      el.innerHTML = '<div class="trip"><div class="trip-top"><span class="dim">' +
        (drops.length ? "every drop is out of range — widen the battery range"
                      : "no drops yet — click the map to add one") +
        "</span></div></div>";
      return;
    }
    for (k = 0; k < S.trips.length; k++) {
      var t = S.trips[k], L = tripLen(t), pct = Math.max(2, Math.min(100, L / RU * 100));
      var col = tripColor(k);
      html += '<div class="trip">' +
        '<div class="trip-top">' +
          '<span class="sw" style="background:' + col + '"></span>' +
          '<span class="nm" style="color:' + col + '">TRIP ' + (k + 1) + "</span>" +
          '<span class="dim">' + t.length + (t.length === 1 ? " parcel" : " parcels") + "</span>" +
          '<span class="sp"></span>' +
          "<span>" + f2(L) + " km</span>" +
          '<span class="dim">' + Math.round(L / RU * 100) + "% of charge</span>" +
        "</div>" +
        '<div class="bar"><i style="width:' + pct.toFixed(1) + "%;background:" + col + '"></i></div>' +
      "</div>";
    }
    el.innerHTML = html;
  }

  /* The out-of-range notice has to be kept in step even when nothing at all is
     reachable — that is exactly the case it exists for. */
  function paintWarn() {
    var w = $("warn");
    if (S.far.length) {
      var need = 0;
      for (var i = 0; i < S.far.length; i++) need = Math.max(need, 2 * dist(S.far[i], DEPOT));
      $("warnTitle").textContent = S.far.length + (S.far.length === 1 ? " drop out of range" : " drops out of range");
      $("warnBody").textContent =
        "The van cannot get there and back on one charge. A range of " + f1(Math.ceil(need)) +
        " km or more would cover " + (S.far.length === 1 ? "it" : "them all") + ".";
      w.classList.add("show");
    } else {
      w.classList.remove("show");
    }
  }

  function describe() {
    if (!S.n) return "Route map. No drops are currently in range of the depot.";
    var s = "Route map. " + S.trips.length + (S.trips.length === 1 ? " trip" : " trips") +
            " from the depot covering " + S.n + (S.n === 1 ? " drop, " : " drops, ") + f2(S.cost) + " km in total. ";
    for (var k = 0; k < S.trips.length; k++) {
      var c = S.trips[k].length;
      s += "Trip " + (k + 1) + ": " + c + (c === 1 ? " drop, " : " drops, ") +
           f2(tripLen(S.trips[k])) + " km. ";
    }
    if (S.far.length) s += S.far.length + (S.far.length === 1 ? " drop is" : " drops are") + " out of range.";
    return s;
  }

  var CV_HINT = " Move the crosshair with the arrow keys and press Enter to add or remove a drop there.";

  function setAlt() {
    var d = describe();
    $("cvAlt").textContent = d;
    cv.setAttribute("aria-label", d + CV_HINT);
  }

  function paintAll() {
    indexTrips();
    paintStats();
    paintTrips();
    setAlt();
  }

  function readout(msg) { $("readout").innerHTML = msg; }
  var DEFAULT_READ = "Click anywhere on the map to add a drop — or click a drop to cancel it.";

  /* ------------------------------------------------------------------ *
   * Solve + animate
   * ------------------------------------------------------------------ */
  function reduced() {
    return !!(window.matchMedia && window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }
  function stop() {
    if (raf) { cancelAnimationFrame(raf); raf = null; }
    flash = null; scan = null; recut = false;
  }

  function fresh() {
    var t0 = now();
    prep();
    S.order = nearestFirst();
    var r = greedySplit(S.order);
    S.naiveCost = r.cost; S.naiveTrips = r.trips;
    S.cost = r.cost; S.trips = r.trips; S.moves = 0;
    solveMs = now() - t0;
  }

  function optimizeSync(budgetMs) {
    var t0 = now(), guard = 0;
    if (S.n) S.cost = splitCost(S.order);   /* optimal trip cuts for this order */
    while (guard++ < 500) {
      if (now() - t0 > (budgetMs || 18)) break;
      var m = bestMove();
      if (!m) break;
      rev(S.order, m.i, m.j);
      S.cost = m.cost; S.moves++;
    }
    var r = splitTrips(S.order);
    S.cost = r.cost; S.trips = r.trips;
    solveMs += now() - t0;
  }

  function finishRun() {
    phase = "done";
    paintAll();
    if (S.far.length) {
      setStatus("warn", S.far.length + " out of range");
    } else if (S.n) {
      setStatus("ok", "route ready");
    } else {
      setStatus("warn", "no drops");
    }
    var imp = (S.naiveCost > 0) ? (S.naiveCost - S.cost) / S.naiveCost * 100 : 0;
    $("pass").innerHTML = !S.n ? "waiting for drops"
      : (S.moves ? "2-opt settled after <b>" + S.moves + "</b> swap" + (S.moves === 1 ? "" : "s")
                 : "no crossings left to undo");
    $("perf").textContent = drops.length + " drops · " + S.trips.length + " trips · " +
      S.moves + " swaps · " + solveMs.toFixed(1) + " ms";
    $("live").textContent = !S.n ? "No drops in range."
      : "Route planned: " + S.trips.length + (S.trips.length === 1 ? " trip, " : " trips, ") + f2(S.cost) + " km total, " +
        imp.toFixed(1) + "% shorter than the first guess.";
    draw();
  }

  function tick(ts) {
    raf = requestAnimationFrame(tick);
    if (phase === "build") {
      if (ts >= nextT) {
        buildK++;
        nextT = ts + Math.max(26, 480 / Math.max(1, S.n));
        if (buildK >= S.n) startOpt(ts);
      }
      draw(ts);
      return;
    }
    if (phase === "opt") {
      if (ts < nextT) { draw(ts); return; }
      if (recut) { doRecut(ts); draw(ts); return; }
      if (!scan) newPass();
      var t0 = now();
      var complete = scanStep();
      solveMs += now() - t0;
      if (!complete) {
        $("pass").innerHTML = "2-opt · testing pair <b>" + scan.tested + "</b>/" + scan.total +
          (scan.bi >= 0 ? " · best so far &minus;" + f2(S.cost - scan.bc) + " km" : "");
      } else if (scan.bi >= 0) {
        rev(S.order, scan.bi, scan.bj);
        S.cost = scan.bc; S.moves++;
        S.trips = splitTrips(S.order).trips;
        flash = { i: scan.bi, j: scan.bj, t: ts };
        indexTrips(); paintStats(); paintTrips();
        $("pass").innerHTML = "flipped a stretch · swap <b>" + S.moves + "</b> · &minus;" +
          f2(S.naiveCost - S.cost) + " km so far";
        scan = null;
        nextT = ts + 300;
      } else {
        finishRun();
      }
      draw(ts);
      return;
    }
    draw(ts);
    if (!flash) { cancelAnimationFrame(raf); raf = null; }
  }

  function newPass() {
    var n = S.n, total = n * (n - 1) / 2;
    scan = {
      i: 0, j: 1, bi: -1, bj: -1, bc: S.cost - 1e-7,
      tested: 0, total: total, per: Math.max(1, Math.ceil(total / 18))
    };
  }

  /* Try every pair of positions, reverse the stretch between them, keep the
     single best flip of the pass. A few candidates per frame, so the search
     itself is visible. */
  function scanStep() {
    var ord = S.order, n = ord.length, k = 0;
    while (k++ < scan.per && scan.i < n - 1) {
      rev(ord, scan.i, scan.j);
      var c = splitCost(ord);
      if (c < scan.bc) { scan.bc = c; scan.bi = scan.i; scan.bj = scan.j; }
      rev(ord, scan.i, scan.j);
      scan.tested++;
      scan.j++;
      if (scan.j >= n) { scan.i++; scan.j = scan.i + 1; }
    }
    return scan.i >= n - 1;
  }

  /* The first thing the planner does: keep the order, but cut the trips in the
     best possible places instead of just flying home when the charge runs low. */
  function doRecut(ts) {
    recut = false;
    var t0 = now();
    var dp = S.n ? splitCost(S.order) : 0;
    solveMs += now() - t0;
    if (dp < S.cost - 1e-7) {
      S.cost = dp;
      S.trips = splitTrips(S.order).trips;
      indexTrips(); paintStats(); paintTrips();
      $("pass").innerHTML = "better places to turn for home · &minus;" +
        f2(S.naiveCost - S.cost) + " km";
      nextT = ts + 420;
    } else {
      S.cost = dp;
      $("pass").innerHTML = "2-opt · looking for crossings…";
      nextT = ts + 120;
    }
  }

  function startOpt(ts) {
    phase = "opt";
    recut = true; scan = null;
    nextT = ts + 260;
    indexTrips(); paintStats(); paintTrips();
    setStatus("load", "untangling…");
    $("pass").innerHTML = "first guess done · " + f2(S.naiveCost) + " km over " +
      S.trips.length + (S.trips.length === 1 ? " trip" : " trips");
  }

  /* mode: "full" = animate the first guess too, "opt" = jump straight to
     untangling, "sync" = solve instantly (slider drags, reduced motion) */
  function run(mode) {
    stop();
    fresh();
    if (hover >= S.n) hover = -1;
    if (mode === "sync" || reduced() || S.n < 4) {
      optimizeSync(mode === "sync" ? 14 : 40);
      finishRun();
      return;
    }
    hover = -1;
    if (mode === "full") {
      phase = "build"; buildK = 0; nextT = 0;
      setStatus("load", "nearest drop each time…");
      $("pass").innerHTML = "first guess · always hop to the nearest drop";
      paintStats(); paintTrips(); setAlt();
    } else {
      phase = "opt"; recut = true; scan = null; nextT = now() + 90;
      indexTrips(); paintStats(); paintTrips();
      setStatus("load", "re-planning…");
      $("pass").innerHTML = "first guess · " + f2(S.naiveCost) + " km";
    }
    raf = requestAnimationFrame(tick);
  }

  /* ------------------------------------------------------------------ *
   * Editing the map
   * ------------------------------------------------------------------ */
  function nearestDrop(x, y) {
    var b = -1, bd = HIT;
    for (var i = 0; i < drops.length; i++) {
      var d = Math.sqrt((drops[i].x - x) * (drops[i].x - x) + (drops[i].y - y) * (drops[i].y - y));
      if (d < bd) { bd = d; b = i; }
    }
    return b;
  }

  function toggleAt(x, y) {
    x = Math.max(2, Math.min(MW - 2, x));
    y = Math.max(2, Math.min(MH - 2, y));
    var hit = nearestDrop(x, y);
    if (hit >= 0) {
      drops.splice(hit, 1);
      readout('<span class="hl">drop cancelled</span> · ' + drops.length + " left");
      run("opt");
      return;
    }
    if (dist({ x: x, y: y }, DEPOT) < 4.5) {
      readout("that spot is the depot — drop somewhere else");
      return;
    }
    if (drops.length >= MAXD) {
      readout('<span class="hl">' + MAXD + " drops is the limit</span> · cancel one first");
      return;
    }
    drops.push({ x: Math.round(x * 2) / 2, y: Math.round(y * 2) / 2 });
    readout('<span class="hl">drop added</span> · ' + drops.length + " on the round");
    run("opt");
  }

  cv.addEventListener("click", function (e) {
    var r = cv.getBoundingClientRect();
    var p = inv(e.clientX - r.left, e.clientY - r.top);
    kb = false;
    toggleAt(p.x, p.y);
  });

  cv.addEventListener("mousemove", function (e) {
    var r = cv.getBoundingClientRect();
    var p = inv(e.clientX - r.left, e.clientY - r.top);
    var h = -1, i;
    for (i = 0; i < S.pts.length; i++) {
      if (dist(S.pts[i], p) < HIT) { h = i; break; }
    }
    if (h !== hover) {
      hover = h;
      if (h >= 0) {
        var meta = S.of && S.of[h];
        readout("<b>drop " + (meta ? "#" + meta.seq + " on trip " + (meta.t + 1) : "—") + "</b> · " +
                f2(S.Ddep[h]) + " km from the depot · <span class=\"hl\">click to cancel it</span>");
      } else {
        readout(DEFAULT_READ);
      }
      draw();
    }
    cv.style.cursor = h >= 0 ? "pointer" : "crosshair";
  });

  cv.addEventListener("mouseleave", function () {
    if (hover !== -1) { hover = -1; readout(DEFAULT_READ); draw(); }
  });

  cv.addEventListener("keydown", function (e) {
    var k = e.key, step = e.shiftKey ? 1 : 4, moved = true;
    if (k === "ArrowLeft") cur.x -= step;
    else if (k === "ArrowRight") cur.x += step;
    else if (k === "ArrowUp") cur.y -= step;
    else if (k === "ArrowDown") cur.y += step;
    else if (k === "Enter" || k === " " || k === "Spacebar") { moved = false; }
    else return;
    e.preventDefault();
    kb = true;
    cur.x = Math.max(2, Math.min(MW - 2, cur.x));
    cur.y = Math.max(2, Math.min(MH - 2, cur.y));
    if (moved) {
      var h = nearestDrop(cur.x, cur.y);
      var away = "<b>" + f2(dist(cur, DEPOT)) + " km</b> from the depot";
      readout(h >= 0
        ? "crosshair on a drop · " + away + ' · <span class="hl">Enter cancels it</span>'
        : "crosshair · " + away + ' · <span class="hl">Enter drops a parcel here</span>');
      draw();
    } else {
      toggleAt(cur.x, cur.y);
      kb = true;
      draw();
    }
  });

  cv.addEventListener("focus", function () {
    kb = true;   /* show the crosshair straight away, not only after a key press */
    readout("arrow keys move the crosshair · Enter adds or cancels a drop");
    draw();
  });
  cv.addEventListener("blur", function () { kb = false; readout(DEFAULT_READ); draw(); });

  /* ------------------------------------------------------------------ *
   * Controls
   * ------------------------------------------------------------------ */
  function labelRange() {
    $("v-rng").textContent = f1(RU) + " km";
    $("h-rng").textContent = "one charge, out and back — reaches " + f1(RU / 2) + " km from the depot";
    $("rng").setAttribute("aria-valuetext", f1(RU) + " km per charge");
  }

  function setPreset(name) {
    var list = PRESETS[name] || PRESETS.spread;
    drops = list.map(function (p) { return { x: p[0], y: p[1] }; });
    var btns = document.querySelectorAll("[data-preset]");
    for (var i = 0; i < btns.length; i++) {
      btns[i].setAttribute("aria-pressed", btns[i].getAttribute("data-preset") === name ? "true" : "false");
    }
  }
  function clearPreset() {
    var btns = document.querySelectorAll("[data-preset]");
    for (var i = 0; i < btns.length; i++) btns[i].setAttribute("aria-pressed", "false");
  }

  (function () {
    var btns = document.querySelectorAll("[data-preset]");
    for (var i = 0; i < btns.length; i++) {
      btns[i].addEventListener("click", function () {
        setPreset(this.getAttribute("data-preset"));
        readout(DEFAULT_READ);
        run("full");
      });
    }
  })();

  /* A drag fires many input events, so each one only gets a small slice of
     2-opt. When the drag stops, finish the job so the route you are left
     looking at is the same one "re-plan" would give you. */
  var settleT = null;
  $("rng").addEventListener("input", function () {
    RU = +this.value;
    labelRange();
    run("sync");
    if (settleT) clearTimeout(settleT);
    settleT = setTimeout(function () {
      settleT = null;
      if (phase !== "done" || !S || !S.n) return;
      optimizeSync(60);
      finishRun();
    }, 180);
  });

  $("btn-opt").addEventListener("click", function () { readout(DEFAULT_READ); run("full"); });

  var seed = 20260813;
  function rnd() { seed = (seed * 1664525 + 1013904223) >>> 0; return seed / 4294967296; }
  $("btn-shuffle").addEventListener("click", function () {
    seed = (seed ^ (Date.now() & 0xffffff)) >>> 0;
    var want = 9 + Math.floor(rnd() * 7), out = [], tries = 0;
    while (out.length < want && tries++ < 900) {
      var x = 7 + rnd() * (MW - 14), y = 7 + rnd() * (MH - 14), ok = true;
      if (dist({ x: x, y: y }, DEPOT) < 8) continue;
      for (var i = 0; i < out.length; i++) {
        if (dist({ x: x, y: y }, out[i]) < 8.5) { ok = false; break; }
      }
      if (ok) out.push({ x: Math.round(x * 2) / 2, y: Math.round(y * 2) / 2 });
    }
    drops = out;
    clearPreset();
    readout(DEFAULT_READ);
    run("full");
  });

  $("btn-reset").addEventListener("click", function () {
    RU = 140; $("rng").value = "140"; labelRange();
    ghostOn = false; $("btn-ghost").setAttribute("aria-pressed", "false");
    reachOn = true; $("btn-reach").setAttribute("aria-pressed", "true");
    setPreset("spread");
    readout(DEFAULT_READ);
    run("full");
  });

  $("btn-ghost").addEventListener("click", function () {
    ghostOn = !ghostOn;
    this.setAttribute("aria-pressed", ghostOn ? "true" : "false");
    readout(ghostOn
      ? (S && S.n && S.naiveCost - S.cost < 1e-6
          ? 'the first guess was already the best route — the <span class="hl">dashed grey</span> line sits exactly under it'
          : 'the <span class="hl">dashed grey</span> line is the first-guess route, before untangling')
      : DEFAULT_READ);
    draw();
  });

  $("btn-reach").addEventListener("click", function () {
    reachOn = !reachOn;
    this.setAttribute("aria-pressed", reachOn ? "true" : "false");
    readout(reachOn
      ? (RU / 2 >= CORNER
          ? "reach is " + f1(RU / 2) + " km — wider than this map, so nothing here is out of reach"
          : "the dashed ring is how far the van can get and still come home")
      : DEFAULT_READ);
    draw();
  });

  /* ------------------------------------------------------------------ *
   * Theme + resize
   * ------------------------------------------------------------------ */
  function themeChanged() {
    colors();
    if (S) paintTrips();
    draw();
  }
  window.addEventListener("message", function (e) {
    var d = e.data;
    if (d && d.type === "sloprun:theme" && (d.theme === "light" || d.theme === "dark")) {
      document.documentElement.setAttribute("data-theme", d.theme);
      themeChanged();
    }
  });
  var mq = window.matchMedia("(prefers-color-scheme: dark)");
  if (mq.addEventListener) mq.addEventListener("change", themeChanged);
  else if (mq.addListener) mq.addListener(themeChanged);

  function onResize() { if (layout()) draw(); }
  if (window.ResizeObserver) {
    var ro = new ResizeObserver(function () { onResize(); });
    ro.observe(cv.parentNode);
  } else {
    window.addEventListener("resize", onResize);
  }

  /* ------------------------------------------------------------------ *
   * Go
   * ------------------------------------------------------------------ */
  $("note").textContent =
    "First guess: always hop to the nearest parcel you have not done yet, and turn for home when " +
    "the next one would not fit on the charge. Then the planner re-cuts the trips in the best " +
    "possible places, and runs 2-opt: try every pair of positions, flip the stretch of drops " +
    "between them, keep the flip that shortens the round the most, repeat until nothing helps. " +
    "Crossed legs are always worth flipping, which is why the tangles come out. No trip is ever " +
    "allowed to exceed one charge. Distances here are straight lines across the grid, not road miles.";

  colors();
  layout();
  setPreset("spread");
  labelRange();
  run("full");
})();
</script>
</body>
</html>