reifydb-core 0.9.0

Core database interfaces and data structures for ReifyDB
Documentation
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
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
// SPDX-License-Identifier: Apache-2.0
// Copyright (c) 2026 ReifyDB

use std::{fmt, str::FromStr};

use reifydb_runtime::version_epoch::BUCKET_WIDTH;
use reifydb_value::value::{Value, duration::Duration, value_type::ValueType};

use crate::common::CommitVersion;

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum AcceptError {
	TypeMismatch {
		expected: Vec<ValueType>,
		actual: ValueType,
	},

	InvalidValue(String),
}

impl fmt::Display for AcceptError {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		match self {
			Self::TypeMismatch {
				expected,
				actual,
			} => {
				write!(f, "expected one of {:?}, got {:?}", expected, actual)
			}
			Self::InvalidValue(reason) => write!(f, "{reason}"),
		}
	}
}

#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub enum ConfigKey {
	OracleWindowSize,
	QueryRowBatchSize,
	QueryMemoryLimit,
	RetentionEvictInterval,
	RetentionEvictBatchSize,
	RetentionEvictMaxBatchesPerTick,
	EpochBucketInterval,
	RetentionStartupGrace,
	MaxRetentionHorizonFloor,
	HistoricalGcBatchSize,
	HistoricalGcInterval,
	CdcTtlDuration,
	CdcTtlScanInterval,
	CdcTtlScanBatchSize,
	CdcCompactInterval,
	CdcCompactBlockSize,
	CdcCompactSafetyLag,
	CdcCompactMaxBlocksPerTick,
	CdcCompactBlockCacheCapacity,
	CdcCompactZstdLevel,
	CdcWalAutocheckpoint,
	MultiReadBufferPages,
	MultiReadBufferPageSize,
	MultiReadBufferBytes,
	MultiFlushInterval,
	MultiFlushKeyBudget,
	MultiWalAutocheckpoint,
	FlowTick,
	FlowSampleInterval,
	FlowBacklogMemoryLimit,
	FlowPullBatchBytes,
	FlowLoadBatchBytes,
	CdcConsumeWaitTimeout,
	FlowJoinProbeBlockSize,
	ThreadsAsync,
	ThreadsCoordination,
	ThreadsFlow,
	ThreadsTask,
	ThreadsCompute,
	SubscriptionWorkerThreads,
	MetricsFlushInterval,
	MetricsSampleInterval,
	MetricsSnapshotInterval,
	CommitGroupLinger,
	CommitGroupMaxEntries,
	TombstoneReapInterval,
	TombstoneReapBatchSize,
}

impl ConfigKey {
	pub fn all() -> &'static [Self] {
		&[
			Self::OracleWindowSize,
			Self::QueryRowBatchSize,
			Self::QueryMemoryLimit,
			Self::RetentionEvictInterval,
			Self::RetentionEvictBatchSize,
			Self::RetentionEvictMaxBatchesPerTick,
			Self::EpochBucketInterval,
			Self::RetentionStartupGrace,
			Self::MaxRetentionHorizonFloor,
			Self::HistoricalGcBatchSize,
			Self::HistoricalGcInterval,
			Self::CdcTtlDuration,
			Self::CdcTtlScanInterval,
			Self::CdcTtlScanBatchSize,
			Self::CdcCompactInterval,
			Self::CdcCompactBlockSize,
			Self::CdcCompactSafetyLag,
			Self::CdcCompactMaxBlocksPerTick,
			Self::CdcCompactBlockCacheCapacity,
			Self::CdcCompactZstdLevel,
			Self::CdcWalAutocheckpoint,
			Self::MultiReadBufferPages,
			Self::MultiReadBufferPageSize,
			Self::MultiReadBufferBytes,
			Self::MultiFlushInterval,
			Self::MultiFlushKeyBudget,
			Self::MultiWalAutocheckpoint,
			Self::FlowTick,
			Self::FlowSampleInterval,
			Self::FlowBacklogMemoryLimit,
			Self::FlowPullBatchBytes,
			Self::FlowLoadBatchBytes,
			Self::CdcConsumeWaitTimeout,
			Self::FlowJoinProbeBlockSize,
			Self::ThreadsAsync,
			Self::ThreadsCoordination,
			Self::ThreadsFlow,
			Self::ThreadsTask,
			Self::ThreadsCompute,
			Self::SubscriptionWorkerThreads,
			Self::MetricsFlushInterval,
			Self::MetricsSampleInterval,
			Self::MetricsSnapshotInterval,
			Self::CommitGroupLinger,
			Self::CommitGroupMaxEntries,
			Self::TombstoneReapInterval,
			Self::TombstoneReapBatchSize,
		]
	}

	pub fn default_value(&self) -> Value {
		match self {
			Self::OracleWindowSize => Value::Uint8(500),
			Self::QueryRowBatchSize => Value::Uint2(128),
			Self::QueryMemoryLimit => Value::Uint8(1024 * 1024 * 1024),
			Self::RetentionEvictInterval => Value::duration_seconds(60),
			Self::RetentionEvictBatchSize => Value::Uint8(1024),
			Self::RetentionEvictMaxBatchesPerTick => Value::Uint8(8),
			Self::EpochBucketInterval => Value::duration_seconds(60),
			Self::RetentionStartupGrace => Value::duration_seconds(300),
			Self::MaxRetentionHorizonFloor => Value::duration_seconds(7 * 24 * 60 * 60),
			Self::HistoricalGcBatchSize => Value::Uint8(50_000),
			Self::HistoricalGcInterval => Value::duration_seconds(30),
			Self::CdcTtlDuration => Value::None {
				inner: ValueType::Duration,
			},
			Self::CdcTtlScanInterval => Value::duration_seconds(30),
			Self::CdcTtlScanBatchSize => Value::Uint8(8192),
			Self::CdcCompactInterval => Value::duration_seconds(60),
			Self::CdcCompactBlockSize => Value::Uint8(1024),
			Self::CdcCompactSafetyLag => Value::Uint8(1024),
			Self::CdcCompactMaxBlocksPerTick => Value::Uint8(16),
			Self::CdcCompactBlockCacheCapacity => Value::Uint8(8),
			Self::CdcCompactZstdLevel => Value::Uint1(2),
			Self::CdcWalAutocheckpoint => Value::Uint8(10000),
			Self::MultiReadBufferPages => Value::Uint8(1024),
			Self::MultiReadBufferPageSize => Value::Uint8(65536),
			Self::MultiReadBufferBytes => Value::Uint8(64 * 1024 * 1024),
			Self::MultiFlushInterval => Value::duration_seconds(5),
			Self::MultiFlushKeyBudget => Value::Uint8(2048),
			Self::MultiWalAutocheckpoint => Value::Uint8(10000),
			Self::FlowTick => Value::duration_seconds(1),
			Self::FlowSampleInterval => Value::duration_seconds(60),
			Self::FlowBacklogMemoryLimit => Value::Uint8(64 * 1024 * 1024),
			Self::FlowPullBatchBytes => Value::Uint8(8 * 1024 * 1024),
			Self::FlowLoadBatchBytes => Value::Uint8(8 * 1024 * 1024),
			Self::CdcConsumeWaitTimeout => Value::duration_seconds(30),
			Self::FlowJoinProbeBlockSize => Value::Uint8(1024),
			Self::ThreadsAsync => Value::Uint2(1),
			Self::ThreadsCoordination => Value::Uint2(2),
			Self::ThreadsFlow => Value::Uint2(2),
			Self::ThreadsTask => Value::Uint2(2),
			Self::ThreadsCompute => Value::Uint2(2),
			Self::SubscriptionWorkerThreads => Value::Uint2(0),
			Self::MetricsFlushInterval => Value::duration_seconds(10),
			Self::MetricsSampleInterval => Value::duration_seconds(10),
			Self::MetricsSnapshotInterval => Value::None {
				inner: ValueType::Duration,
			},
			Self::CommitGroupLinger => Value::None {
				inner: ValueType::Duration,
			},
			Self::CommitGroupMaxEntries => Value::Uint8(256),
			Self::TombstoneReapInterval => Value::duration_seconds(1),
			Self::TombstoneReapBatchSize => Value::Uint8(1024),
		}
	}

	pub fn description(&self) -> &'static str {
		match self {
			Self::OracleWindowSize => "Number of transactions per conflict-detection window.",
			Self::QueryRowBatchSize => {
				"Number of rows produced per batch by query / DML pipeline operators."
			}
			Self::QueryMemoryLimit => {
				"Maximum bytes a single query may buffer in memory across its blocking operators (joins, sort, top k, distinct) and its accumulated result. A query that would exceed this fails with QUERY_006 instead of growing without bound. Read fresh for each query, so changes take effect immediately."
			}
			Self::RetentionEvictInterval => {
				"How often the retention evictor scans objects with a row TTL for expired rows."
			}
			Self::RetentionEvictBatchSize => {
				"Max rows examined (and thus evicted) per transaction during a retention eviction tick."
			}
			Self::RetentionEvictMaxBatchesPerTick => {
				"Upper bound on eviction transactions per retention tick. Caps how long one tick can run when draining a backlog; remaining work resumes on the next tick."
			}
			Self::EpochBucketInterval => {
				"Wall-clock width of one durable version-epoch bucket. The epoch log persists at most one \
				 (bucket, commit version) sample per bucket, and those samples are what let TTLs resolve a \
				 cutoff after a restart. Smaller buckets give finer expiry resolution at the cost of more \
				 persisted samples over the retention horizon."
			}
			Self::RetentionStartupGrace => {
				"How long after startup every retention executor computes cutoffs but deletes nothing. A \
				 process restarted after a long downtime wakes with a large expired backlog; the grace \
				 period plus per-class budgets drain it over many ticks instead of one mass eviction."
			}
			Self::MaxRetentionHorizonFloor => {
				"Lower bound on the retained version-epoch horizon. The horizon is the longest declared \
				 TTL in the catalog, never less than this floor; epoch samples older than the horizon are \
				 pruned. A TTL longer than the horizon could not resolve a cutoff, so it is rejected at \
				 declaration time rather than silently never expiring."
			}
			Self::HistoricalGcBatchSize => {
				"Max historical (key, version) pairs scanned per object per historical GC tick."
			}
			Self::HistoricalGcInterval => {
				"How often the historical-version GC actor sweeps __historical for versions older than the oracle read watermark."
			}
			Self::CdcTtlDuration => {
				"Maximum age of CDC entries before eviction. When unset, CDC is retained forever; \
				 when set, must be > 0 and entries older than this duration are evicted regardless \
				 of consumer state."
			}
			Self::CdcTtlScanInterval => {
				"How often the CDC producer actor scans for and evicts expired CDC entries."
			}
			Self::CdcTtlScanBatchSize => {
				"Max CDC entries deleted per transaction during a CDC TTL eviction tick."
			}
			Self::CdcCompactInterval => "How often the CDC compaction actor runs.",
			Self::CdcCompactBlockSize => "Number of CDC entries packed into one compressed block.",
			Self::CdcCompactSafetyLag => "Versions newer than (max_version - lag) are never compacted.",
			Self::CdcCompactMaxBlocksPerTick => {
				"Upper bound on consecutive blocks produced per actor tick."
			}
			Self::CdcCompactBlockCacheCapacity => {
				"Number of decompressed CDC blocks held in the in-memory LRU cache."
			}
			Self::CdcCompactZstdLevel => {
				"Zstd compression level for CDC blocks. Range 1-22; higher means smaller blocks but \
				 slower compression. Decompression cost is independent of level."
			}
			Self::CdcWalAutocheckpoint => {
				"WAL frame threshold (SQLite wal_autocheckpoint PRAGMA) for the CDC log's SQLite tier. \
				 CDC has no explicit checkpoint of its own, so this is the sole control over how often \
				 cdc.db's WAL is checkpointed into the main file. Higher values checkpoint less often with \
				 a larger WAL; since CDC is written on the commit path, this also bounds how often a commit \
				 pays an inline auto-checkpoint. Read once at boot; changing it requires a restart."
			}
			Self::MultiReadBufferPages => {
				"Number of pages (contiguous row-number buckets) the multi-version read cache keeps \
				 resident before eviction. Raising it trades RAM for fewer persistent-tier reads."
			}
			Self::MultiReadBufferPageSize => {
				"Number of rows per cached page (bucket) in the multi-version read cache. Must be a \
				 power of two; sets the granularity of whole-page read-ahead and completeness tracking."
			}
			Self::MultiReadBufferBytes => {
				"Resident byte budget for the multi-version read cache, split evenly across its shards. \
				 None disables the cache outright: no page is warmed or inserted, so reads always go to \
				 the persistent tier. Read once at boot; changing it requires a restart."
			}
			Self::MultiFlushInterval => {
				"How often the persistent-flush actor drains the in-memory commit buffer into the multi \
				 store's SQLite tier. Longer intervals coalesce more writes per flush - a larger WAL - at \
				 the cost of more resident commit-buffer memory and a longer window before data is \
				 materialized in the persistent file. Read once at boot; changing it requires a restart."
			}
			Self::MultiFlushKeyBudget => {
				"Maximum keys the persistent-flush class moves from the commit buffer to the SQLite tier \
				 in one slice. Bounds how long a single flush holds the lane, so a large backlog drains \
				 across ticks instead of stalling every other retention class behind it."
			}
			Self::MultiWalAutocheckpoint => {
				"WAL frame threshold for the multi store's SQLite tier: sets the SQLite \
				 wal_autocheckpoint PRAGMA that governs when SQLite folds the WAL back into the main \
				 database. Higher values checkpoint less often with a larger WAL, reducing checkpoint \
				 I/O; lower values keep the WAL small at the cost of more frequent checkpoints. Read once \
				 at boot; changing it requires a restart."
			}
			Self::FlowTick => {
				"How often the deferred and transactional flow tick coordinators wake up to dispatch \
				 due flows."
			}
			Self::FlowSampleInterval => {
				"How often each flow actor samples its operators' approximate memory into the \
				 system::metrics::runtime::memory samples (scope operator::N). Runs on the operator's \
				 own thread, off the apply path. When none, operator sampling is disabled entirely; when \
				 set, must be > 0."
			}
			Self::FlowBacklogMemoryLimit => {
				"Byte ceiling of the shared in-memory backlog of decoded CDC entries that feeds flow \
				 consumers. Producer-fed at commit granularity; entries below every flow's cursor are \
				 dropped eagerly and the lowest versions are evicted first once the ceiling is exceeded, \
				 at which point a flow that far behind reloads from disk through the catch-up loader. \
				 Because payload rows are shared, the tally is an upper bound of unique memory."
			}
			Self::FlowPullBatchBytes => {
				"Byte budget a flow actor applies per pull from the CDC backlog. A flow that has fallen \
				 behind receives up to this many bytes of decoded changes in one slice, so catch-up is \
				 vectorized instead of per-version."
			}
			Self::FlowLoadBatchBytes => {
				"Byte budget of one catch-up loader read from the CDC log on behalf of flows that are \
				 behind the in-memory backlog. Identical concurrent requests share a single read."
			}
			Self::CdcConsumeWaitTimeout => {
				"Backstop timeout for the CDC consumer's wait for a consume reply from the downstream \
				 consumer. A lost reply would otherwise wedge the poll loop forever; on timeout the batch \
				 is re-dispatched without advancing the checkpoint. Must be > 0."
			}
			Self::FlowJoinProbeBlockSize => {
				"Number of opposite-side rows a streaming join pulls per block when probing its stored \
				 state. Bounds resident probe memory without dropping matches; smaller trades fewer \
				 resident rows for more scan round-trips."
			}
			Self::ThreadsAsync => {
				"Number of worker threads for the async runtime. Must be >= 1. \
				 Read at boot before the runtime starts; changes require restart."
			}
			Self::ThreadsCoordination => {
				"Number of worker threads for the coordination group (long-lived actors with \
				 tiny high-frequency handlers and periodic background actors); pinned dispatch. \
				 Must be >= 1. Changes require restart."
			}
			Self::ThreadsFlow => {
				"Number of worker threads for the flow group (long-lived heavy-handler actors: \
				 materialized-view flow execution); pinned dispatch. \
				 Must be >= 1. Changes require restart."
			}
			Self::ThreadsTask => {
				"Number of worker threads for the task pool (short-lived work: per-request \
				 actors and one-shot jobs). Must be >= 1. Changes require restart."
			}
			Self::ThreadsCompute => {
				"Number of worker threads for the compute pool (data-parallel work via install(), \
				 never actors). Must be >= 1. Changes require restart."
			}
			Self::SubscriptionWorkerThreads => {
				"Number of subscription worker actors that fan out CDC changes to ephemeral \
				 subscriptions in parallel. 0 means auto (size to the system thread pool). Higher values \
				 raise fan-out parallelism for many concurrent subscriptions. Changes require restart."
			}
			Self::MetricsFlushInterval => {
				"How often the metric collector flushes accumulated storage and CDC accounting into the \
				 system::metrics KV store that backs the storage and cdc views. Must be > 0."
			}
			Self::MetricsSampleInterval => {
				"How often the metrics sampler polls every domain, rolls the window and publishes the \
				 system::metrics ::current and ::total caches. Always on; there is no off value, only a \
				 cadence. Must be > 0. Read once at boot; changing it requires a restart."
			}
			Self::MetricsSnapshotInterval => {
				"How often the published ::current reading of every domain is appended to its ::snapshots \
				 series. When none, no snapshot is ever written; when set, must be > 0 and not shorter than \
				 METRICS_SAMPLE_INTERVAL. Read once at boot; changing it requires a restart."
			}
			Self::CommitGroupLinger => {
				"Maximum time an unchecked commit submitted to the group-commit coordinator waits \
				 for other commits to join its group before the merged transaction is flushed. \
				 Defaults to none, which disables grouping entirely (every submission commits \
				 immediately in its own transaction); when set, must be > 0. Read once at database \
				 construction, so changing it requires a restart."
			}
			Self::CommitGroupMaxEntries => {
				"Upper bound on commits merged into one group-commit flush. A group is flushed as \
				 soon as it reaches this size, even before the linger expires. Must be > 0."
			}
			Self::TombstoneReapInterval => {
				"How often the tombstone reaper scans persistent tables for delete-mode tombstones whose superseding write has flushed."
			}
			Self::TombstoneReapBatchSize => {
				"Max tombstones one reap statement may physically delete per table per slice. Bounds the write-connection hold; remaining tombstones drain on the next slice."
			}
		}
	}

	pub fn requires_restart(&self) -> bool {
		match self {
			Self::OracleWindowSize => false,
			Self::QueryRowBatchSize => false,
			Self::QueryMemoryLimit => false,
			Self::RetentionEvictInterval => true,
			Self::RetentionEvictBatchSize => false,
			Self::RetentionEvictMaxBatchesPerTick => false,
			Self::EpochBucketInterval => false,
			Self::RetentionStartupGrace => false,
			Self::MaxRetentionHorizonFloor => false,
			Self::HistoricalGcBatchSize => false,
			Self::HistoricalGcInterval => false,
			Self::CdcTtlDuration => false,
			Self::CdcTtlScanInterval => true,
			Self::CdcTtlScanBatchSize => false,
			Self::CdcCompactInterval => false,
			Self::CdcCompactBlockSize => false,
			Self::CdcCompactSafetyLag => false,
			Self::CdcCompactMaxBlocksPerTick => false,
			Self::CdcCompactBlockCacheCapacity => true,
			Self::CdcCompactZstdLevel => false,
			Self::CdcWalAutocheckpoint => true,
			Self::MultiReadBufferPages => true,
			Self::MultiReadBufferPageSize => true,
			Self::MultiReadBufferBytes => true,
			Self::MultiFlushInterval => true,
			Self::MultiFlushKeyBudget => false,
			Self::MultiWalAutocheckpoint => true,
			Self::FlowTick => false,
			Self::FlowSampleInterval => false,
			Self::FlowBacklogMemoryLimit => true,
			Self::FlowPullBatchBytes => true,
			Self::FlowLoadBatchBytes => true,
			Self::CdcConsumeWaitTimeout => false,
			Self::FlowJoinProbeBlockSize => false,
			Self::ThreadsAsync => true,
			Self::ThreadsCoordination => true,
			Self::ThreadsFlow => true,
			Self::ThreadsTask => true,
			Self::ThreadsCompute => true,
			Self::SubscriptionWorkerThreads => true,
			Self::MetricsFlushInterval => false,
			Self::MetricsSampleInterval => true,
			Self::MetricsSnapshotInterval => true,
			Self::CommitGroupLinger => true,
			Self::CommitGroupMaxEntries => true,
			Self::TombstoneReapInterval => false,
			Self::TombstoneReapBatchSize => false,
		}
	}

	pub fn expected_types(&self) -> &'static [ValueType] {
		match self {
			Self::OracleWindowSize => &[ValueType::Uint8],
			Self::QueryRowBatchSize => &[ValueType::Uint2],
			Self::QueryMemoryLimit => &[ValueType::Uint8],
			Self::RetentionEvictInterval => &[ValueType::Duration],
			Self::RetentionEvictBatchSize => &[ValueType::Uint8],
			Self::RetentionEvictMaxBatchesPerTick => &[ValueType::Uint8],
			Self::EpochBucketInterval => &[ValueType::Duration],
			Self::RetentionStartupGrace => &[ValueType::Duration],
			Self::MaxRetentionHorizonFloor => &[ValueType::Duration],
			Self::HistoricalGcBatchSize => &[ValueType::Uint8],
			Self::HistoricalGcInterval => &[ValueType::Duration],
			Self::CdcTtlDuration => &[ValueType::Duration],
			Self::CdcTtlScanInterval => &[ValueType::Duration],
			Self::CdcTtlScanBatchSize => &[ValueType::Uint8],
			Self::CdcCompactInterval => &[ValueType::Duration],
			Self::CdcCompactBlockSize => &[ValueType::Uint8],
			Self::CdcCompactSafetyLag => &[ValueType::Uint8],
			Self::CdcCompactMaxBlocksPerTick => &[ValueType::Uint8],
			Self::CdcCompactBlockCacheCapacity => &[ValueType::Uint8],
			Self::CdcCompactZstdLevel => &[ValueType::Uint1],
			Self::CdcWalAutocheckpoint => &[ValueType::Uint8],
			Self::MultiReadBufferPages => &[ValueType::Uint8],
			Self::MultiReadBufferPageSize => &[ValueType::Uint8],
			Self::MultiReadBufferBytes => &[ValueType::Uint8],
			Self::MultiFlushInterval => &[ValueType::Duration],
			Self::MultiFlushKeyBudget => &[ValueType::Uint8],
			Self::MultiWalAutocheckpoint => &[ValueType::Uint8],
			Self::FlowTick => &[ValueType::Duration],
			Self::FlowSampleInterval => &[ValueType::Duration],
			Self::FlowBacklogMemoryLimit => &[ValueType::Uint8],
			Self::FlowPullBatchBytes => &[ValueType::Uint8],
			Self::FlowLoadBatchBytes => &[ValueType::Uint8],
			Self::CdcConsumeWaitTimeout => &[ValueType::Duration],
			Self::FlowJoinProbeBlockSize => &[ValueType::Uint8],
			Self::ThreadsAsync => &[ValueType::Uint2],
			Self::ThreadsCoordination => &[ValueType::Uint2],
			Self::ThreadsFlow => &[ValueType::Uint2],
			Self::ThreadsTask => &[ValueType::Uint2],
			Self::ThreadsCompute => &[ValueType::Uint2],
			Self::SubscriptionWorkerThreads => &[ValueType::Uint2],
			Self::MetricsFlushInterval => &[ValueType::Duration],
			Self::MetricsSampleInterval => &[ValueType::Duration],
			Self::MetricsSnapshotInterval => &[ValueType::Duration],
			Self::CommitGroupLinger => &[ValueType::Duration],
			Self::CommitGroupMaxEntries => &[ValueType::Uint8],
			Self::TombstoneReapInterval => &[ValueType::Duration],
			Self::TombstoneReapBatchSize => &[ValueType::Uint8],
		}
	}

	pub fn is_optional(&self) -> bool {
		match self {
			Self::OracleWindowSize => false,
			Self::QueryRowBatchSize => false,
			Self::QueryMemoryLimit => false,
			Self::RetentionEvictInterval => false,
			Self::RetentionEvictBatchSize => false,
			Self::RetentionEvictMaxBatchesPerTick => false,
			Self::EpochBucketInterval => false,
			Self::RetentionStartupGrace => false,
			Self::MaxRetentionHorizonFloor => false,
			Self::HistoricalGcBatchSize => false,
			Self::HistoricalGcInterval => false,
			Self::CdcTtlDuration => true,
			Self::CdcTtlScanInterval => false,
			Self::CdcTtlScanBatchSize => false,
			Self::CdcCompactInterval => false,
			Self::CdcCompactBlockSize => false,
			Self::CdcCompactSafetyLag => false,
			Self::CdcCompactMaxBlocksPerTick => false,
			Self::CdcCompactBlockCacheCapacity => false,
			Self::CdcCompactZstdLevel => false,
			Self::CdcWalAutocheckpoint => false,
			Self::MultiReadBufferPages => false,
			Self::MultiReadBufferPageSize => false,
			Self::MultiReadBufferBytes => true,
			Self::MultiFlushInterval => false,
			Self::MultiFlushKeyBudget => false,
			Self::MultiWalAutocheckpoint => false,
			Self::FlowTick => false,
			Self::FlowSampleInterval => true,
			Self::FlowBacklogMemoryLimit => false,
			Self::FlowPullBatchBytes => false,
			Self::FlowLoadBatchBytes => false,
			Self::CdcConsumeWaitTimeout => false,
			Self::FlowJoinProbeBlockSize => false,
			Self::ThreadsAsync => false,
			Self::ThreadsCoordination => false,
			Self::ThreadsFlow => false,
			Self::ThreadsTask => false,
			Self::ThreadsCompute => false,
			Self::SubscriptionWorkerThreads => false,
			Self::MetricsFlushInterval => false,
			Self::MetricsSampleInterval => false,
			Self::MetricsSnapshotInterval => true,
			Self::CommitGroupLinger => true,
			Self::CommitGroupMaxEntries => false,
			Self::TombstoneReapInterval => false,
			Self::TombstoneReapBatchSize => false,
		}
	}

	fn validate_canonical(&self, value: &Value) -> Result<(), String> {
		match self {
			Self::CdcTtlDuration => match value {
				Value::None {
					..
				} => Ok(()),
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("CDC_TTL_DURATION must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::CdcCompactInterval => match value {
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("CDC_COMPACT_INTERVAL must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::EpochBucketInterval => match value {
				Value::Duration(d) if !d.is_positive() => {
					Err("EPOCH_BUCKET_INTERVAL must be greater than zero".to_string())
				}
				Value::Duration(d) if d.to_std().as_secs() < BUCKET_WIDTH.seconds() => Err(format!(
					"EPOCH_BUCKET_INTERVAL must be at least {}s: the version epoch resolves cutoffs at \
					 second granularity, so a shorter bucket truncates to zero and silently disables \
					 coarse compaction",
					BUCKET_WIDTH.seconds()
				)),
				_ => Ok(()),
			},
			Self::RetentionStartupGrace => match value {
				Value::Duration(d) if d.is_negative() => {
					Err("RETENTION_STARTUP_GRACE must not be negative".to_string())
				}
				_ => Ok(()),
			},
			Self::MaxRetentionHorizonFloor => match value {
				Value::Duration(d) if !d.is_positive() => {
					Err("MAX_RETENTION_HORIZON_FLOOR must be greater than zero".to_string())
				}
				_ => Ok(()),
			},
			Self::CdcCompactBlockSize => match value {
				Value::Uint8(0) => Err("CDC_COMPACT_BLOCK_SIZE must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::QueryRowBatchSize => match value {
				Value::Uint2(0) => Err("QUERY_ROW_BATCH_SIZE must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::QueryMemoryLimit => match value {
				Value::Uint8(0) => Err("QUERY_MEMORY_LIMIT must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::FlowBacklogMemoryLimit => match value {
				Value::Uint8(0) => {
					Err("FLOW_BACKLOG_MEMORY_LIMIT must be greater than zero".to_string())
				}
				_ => Ok(()),
			},
			Self::FlowPullBatchBytes => match value {
				Value::Uint8(0) => Err("FLOW_PULL_BATCH_BYTES must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::FlowLoadBatchBytes => match value {
				Value::Uint8(0) => Err("FLOW_LOAD_BATCH_BYTES must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::CdcCompactBlockCacheCapacity => match value {
				Value::Uint8(0) => {
					Err("CDC_COMPACT_BLOCK_CACHE_CAPACITY must be greater than zero".to_string())
				}
				_ => Ok(()),
			},
			Self::MultiReadBufferPages => match value {
				Value::Uint8(0) => Err("MULTI_READ_BUFFER_PAGES must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::MultiReadBufferPageSize => match value {
				Value::Uint8(v) if v.is_power_of_two() => Ok(()),
				Value::Uint8(_) => {
					Err("MULTI_READ_BUFFER_PAGE_SIZE must be a power of two".to_string())
				}
				_ => Ok(()),
			},
			Self::MultiReadBufferBytes => match value {
				Value::Uint8(0) => Err(
					"MULTI_READ_BUFFER_BYTES must be greater than zero; use none to disable the read cache"
						.to_string(),
				),
				_ => Ok(()),
			},
			Self::MultiFlushInterval => match value {
				Value::Duration(d) if d.is_positive() => Ok(()),
				Value::Duration(_) => Err("MULTI_FLUSH_INTERVAL must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::MultiFlushKeyBudget => match value {
				Value::Uint8(n) if *n > 0 => Ok(()),
				Value::Uint8(_) => Err("MULTI_FLUSH_KEY_BUDGET must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::MultiWalAutocheckpoint => match value {
				Value::Uint8(0) => {
					Err("MULTI_WAL_AUTOCHECKPOINT must be greater than zero".to_string())
				}
				_ => Ok(()),
			},
			Self::CdcWalAutocheckpoint => match value {
				Value::Uint8(0) => Err("CDC_WAL_AUTOCHECKPOINT must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::CdcCompactZstdLevel => match value {
				Value::Uint1(v) if (1..=22).contains(v) => Ok(()),
				Value::Uint1(_) => Err("CDC_COMPACT_ZSTD_LEVEL must be in [1, 22]".to_string()),
				_ => Ok(()),
			},
			Self::HistoricalGcBatchSize => match value {
				Value::Uint8(0) => {
					Err("HISTORICAL_GC_BATCH_SIZE must be greater than zero".to_string())
				}
				_ => Ok(()),
			},
			Self::HistoricalGcInterval => match value {
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("HISTORICAL_GC_INTERVAL must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::FlowTick => match value {
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("FLOW_TICK must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::FlowSampleInterval => match value {
				Value::None {
					..
				} => Ok(()),
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("FLOW_SAMPLE_INTERVAL must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::CdcConsumeWaitTimeout => match value {
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("CDC_CONSUME_WAIT_TIMEOUT must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::FlowJoinProbeBlockSize => match value {
				Value::Uint8(0) => {
					Err("FLOW_JOIN_PROBE_BLOCK_SIZE must be greater than zero".to_string())
				}
				_ => Ok(()),
			},
			Self::ThreadsAsync => match value {
				Value::Uint2(0) => Err("THREADS_ASYNC must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::ThreadsCoordination => match value {
				Value::Uint2(0) => Err("THREADS_COORDINATION must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::ThreadsFlow => match value {
				Value::Uint2(0) => Err("THREADS_FLOW must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::ThreadsTask => match value {
				Value::Uint2(0) => Err("THREADS_TASK must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::ThreadsCompute => match value {
				Value::Uint2(0) => Err("THREADS_COMPUTE must be greater than zero".to_string()),
				_ => Ok(()),
			},
			Self::SubscriptionWorkerThreads => Ok(()),
			Self::MetricsFlushInterval => match value {
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("METRICS_FLUSH_INTERVAL must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::MetricsSampleInterval => match value {
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("METRICS_SAMPLE_INTERVAL must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::MetricsSnapshotInterval => match value {
				Value::None {
					..
				} => Ok(()),
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("METRICS_SNAPSHOT_INTERVAL must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::CommitGroupLinger => match value {
				Value::None {
					..
				} => Ok(()),
				Value::Duration(d) => {
					if d.is_positive() {
						Ok(())
					} else {
						Err("COMMIT_GROUP_LINGER must be greater than zero".to_string())
					}
				}
				_ => Ok(()),
			},
			Self::CommitGroupMaxEntries => match value {
				Value::Uint8(0) => {
					Err("COMMIT_GROUP_MAX_ENTRIES must be greater than zero".to_string())
				}
				_ => Ok(()),
			},
			_ => Ok(()),
		}
	}

	pub fn accept(&self, value: Value) -> Result<Value, AcceptError> {
		if let Value::None {
			inner,
		} = &value
		{
			if self.is_optional() && self.expected_types().contains(inner) {
				return Ok(value);
			}
			return Err(AcceptError::TypeMismatch {
				expected: self.expected_types().to_vec(),
				actual: value.get_type(),
			});
		}

		if !self.expected_types().contains(&value.get_type()) {
			return Err(AcceptError::TypeMismatch {
				expected: self.expected_types().to_vec(),
				actual: value.get_type(),
			});
		}

		self.validate_canonical(&value).map_err(AcceptError::InvalidValue)?;
		Ok(value)
	}
}

impl fmt::Display for ConfigKey {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		match self {
			Self::OracleWindowSize => write!(f, "ORACLE_WINDOW_SIZE"),
			Self::QueryRowBatchSize => write!(f, "QUERY_ROW_BATCH_SIZE"),
			Self::QueryMemoryLimit => write!(f, "QUERY_MEMORY_LIMIT"),
			Self::RetentionEvictInterval => write!(f, "RETENTION_EVICT_INTERVAL"),
			Self::RetentionEvictBatchSize => write!(f, "RETENTION_EVICT_BATCH_SIZE"),
			Self::RetentionEvictMaxBatchesPerTick => write!(f, "RETENTION_EVICT_MAX_BATCHES_PER_TICK"),
			Self::EpochBucketInterval => write!(f, "EPOCH_BUCKET_INTERVAL"),
			Self::RetentionStartupGrace => write!(f, "RETENTION_STARTUP_GRACE"),
			Self::MaxRetentionHorizonFloor => write!(f, "MAX_RETENTION_HORIZON_FLOOR"),
			Self::HistoricalGcBatchSize => write!(f, "HISTORICAL_GC_BATCH_SIZE"),
			Self::HistoricalGcInterval => write!(f, "HISTORICAL_GC_INTERVAL"),
			Self::CdcTtlDuration => write!(f, "CDC_TTL_DURATION"),
			Self::CdcTtlScanInterval => write!(f, "CDC_TTL_SCAN_INTERVAL"),
			Self::CdcTtlScanBatchSize => write!(f, "CDC_TTL_SCAN_BATCH_SIZE"),
			Self::CdcCompactInterval => write!(f, "CDC_COMPACT_INTERVAL"),
			Self::CdcCompactBlockSize => write!(f, "CDC_COMPACT_BLOCK_SIZE"),
			Self::CdcCompactSafetyLag => write!(f, "CDC_COMPACT_SAFETY_LAG"),
			Self::CdcCompactMaxBlocksPerTick => write!(f, "CDC_COMPACT_MAX_BLOCKS_PER_TICK"),
			Self::CdcCompactBlockCacheCapacity => write!(f, "CDC_COMPACT_BLOCK_CACHE_CAPACITY"),
			Self::CdcCompactZstdLevel => write!(f, "CDC_COMPACT_ZSTD_LEVEL"),
			Self::CdcWalAutocheckpoint => write!(f, "CDC_WAL_AUTOCHECKPOINT"),
			Self::MultiReadBufferPages => write!(f, "MULTI_READ_BUFFER_PAGES"),
			Self::MultiReadBufferPageSize => write!(f, "MULTI_READ_BUFFER_PAGE_SIZE"),
			Self::MultiReadBufferBytes => write!(f, "MULTI_READ_BUFFER_BYTES"),
			Self::MultiFlushInterval => write!(f, "MULTI_FLUSH_INTERVAL"),
			Self::MultiFlushKeyBudget => write!(f, "MULTI_FLUSH_KEY_BUDGET"),
			Self::MultiWalAutocheckpoint => write!(f, "MULTI_WAL_AUTOCHECKPOINT"),
			Self::FlowTick => write!(f, "FLOW_TICK"),
			Self::FlowSampleInterval => write!(f, "FLOW_SAMPLE_INTERVAL"),
			Self::FlowBacklogMemoryLimit => write!(f, "FLOW_BACKLOG_MEMORY_LIMIT"),
			Self::FlowPullBatchBytes => write!(f, "FLOW_PULL_BATCH_BYTES"),
			Self::FlowLoadBatchBytes => write!(f, "FLOW_LOAD_BATCH_BYTES"),
			Self::CdcConsumeWaitTimeout => write!(f, "CDC_CONSUME_WAIT_TIMEOUT"),
			Self::FlowJoinProbeBlockSize => write!(f, "FLOW_JOIN_PROBE_BLOCK_SIZE"),
			Self::ThreadsAsync => write!(f, "THREADS_ASYNC"),
			Self::ThreadsCoordination => write!(f, "THREADS_COORDINATION"),
			Self::ThreadsFlow => write!(f, "THREADS_FLOW"),
			Self::ThreadsTask => write!(f, "THREADS_TASK"),
			Self::ThreadsCompute => write!(f, "THREADS_COMPUTE"),
			Self::SubscriptionWorkerThreads => write!(f, "SUBSCRIPTION_WORKER_THREADS"),
			Self::MetricsFlushInterval => write!(f, "METRICS_FLUSH_INTERVAL"),
			Self::MetricsSampleInterval => write!(f, "METRICS_SAMPLE_INTERVAL"),
			Self::MetricsSnapshotInterval => write!(f, "METRICS_SNAPSHOT_INTERVAL"),
			Self::CommitGroupLinger => write!(f, "COMMIT_GROUP_LINGER"),
			Self::CommitGroupMaxEntries => write!(f, "COMMIT_GROUP_MAX_ENTRIES"),
			Self::TombstoneReapInterval => write!(f, "TOMBSTONE_REAP_INTERVAL"),
			Self::TombstoneReapBatchSize => write!(f, "TOMBSTONE_REAP_BATCH_SIZE"),
		}
	}
}

impl FromStr for ConfigKey {
	type Err = String;

	fn from_str(s: &str) -> Result<Self, Self::Err> {
		match s {
			"ORACLE_WINDOW_SIZE" => Ok(Self::OracleWindowSize),
			"QUERY_ROW_BATCH_SIZE" => Ok(Self::QueryRowBatchSize),
			"QUERY_MEMORY_LIMIT" => Ok(Self::QueryMemoryLimit),
			"RETENTION_EVICT_INTERVAL" => Ok(Self::RetentionEvictInterval),
			"RETENTION_EVICT_BATCH_SIZE" => Ok(Self::RetentionEvictBatchSize),
			"RETENTION_EVICT_MAX_BATCHES_PER_TICK" => Ok(Self::RetentionEvictMaxBatchesPerTick),
			"EPOCH_BUCKET_INTERVAL" => Ok(Self::EpochBucketInterval),
			"RETENTION_STARTUP_GRACE" => Ok(Self::RetentionStartupGrace),
			"MAX_RETENTION_HORIZON_FLOOR" => Ok(Self::MaxRetentionHorizonFloor),
			"HISTORICAL_GC_BATCH_SIZE" => Ok(Self::HistoricalGcBatchSize),
			"HISTORICAL_GC_INTERVAL" => Ok(Self::HistoricalGcInterval),
			"CDC_TTL_DURATION" => Ok(Self::CdcTtlDuration),
			"CDC_TTL_SCAN_INTERVAL" => Ok(Self::CdcTtlScanInterval),
			"CDC_TTL_SCAN_BATCH_SIZE" => Ok(Self::CdcTtlScanBatchSize),
			"CDC_COMPACT_INTERVAL" => Ok(Self::CdcCompactInterval),
			"CDC_COMPACT_BLOCK_SIZE" => Ok(Self::CdcCompactBlockSize),
			"CDC_COMPACT_SAFETY_LAG" => Ok(Self::CdcCompactSafetyLag),
			"CDC_COMPACT_MAX_BLOCKS_PER_TICK" => Ok(Self::CdcCompactMaxBlocksPerTick),
			"CDC_COMPACT_BLOCK_CACHE_CAPACITY" => Ok(Self::CdcCompactBlockCacheCapacity),
			"CDC_COMPACT_ZSTD_LEVEL" => Ok(Self::CdcCompactZstdLevel),
			"CDC_WAL_AUTOCHECKPOINT" => Ok(Self::CdcWalAutocheckpoint),
			"MULTI_READ_BUFFER_PAGES" => Ok(Self::MultiReadBufferPages),
			"MULTI_READ_BUFFER_PAGE_SIZE" => Ok(Self::MultiReadBufferPageSize),
			"MULTI_READ_BUFFER_BYTES" => Ok(Self::MultiReadBufferBytes),
			"MULTI_FLUSH_INTERVAL" => Ok(Self::MultiFlushInterval),
			"MULTI_FLUSH_KEY_BUDGET" => Ok(Self::MultiFlushKeyBudget),
			"MULTI_WAL_AUTOCHECKPOINT" => Ok(Self::MultiWalAutocheckpoint),
			"FLOW_TICK" => Ok(Self::FlowTick),
			"FLOW_SAMPLE_INTERVAL" => Ok(Self::FlowSampleInterval),
			"FLOW_BACKLOG_MEMORY_LIMIT" => Ok(Self::FlowBacklogMemoryLimit),
			"FLOW_PULL_BATCH_BYTES" => Ok(Self::FlowPullBatchBytes),
			"FLOW_LOAD_BATCH_BYTES" => Ok(Self::FlowLoadBatchBytes),
			"CDC_CONSUME_WAIT_TIMEOUT" => Ok(Self::CdcConsumeWaitTimeout),
			"FLOW_JOIN_PROBE_BLOCK_SIZE" => Ok(Self::FlowJoinProbeBlockSize),
			"THREADS_ASYNC" => Ok(Self::ThreadsAsync),
			"THREADS_COORDINATION" => Ok(Self::ThreadsCoordination),
			"THREADS_FLOW" => Ok(Self::ThreadsFlow),
			"THREADS_TASK" => Ok(Self::ThreadsTask),
			"THREADS_COMPUTE" => Ok(Self::ThreadsCompute),
			"SUBSCRIPTION_WORKER_THREADS" => Ok(Self::SubscriptionWorkerThreads),
			"METRICS_FLUSH_INTERVAL" => Ok(Self::MetricsFlushInterval),
			"METRICS_SAMPLE_INTERVAL" => Ok(Self::MetricsSampleInterval),
			"METRICS_SNAPSHOT_INTERVAL" => Ok(Self::MetricsSnapshotInterval),
			"COMMIT_GROUP_LINGER" => Ok(Self::CommitGroupLinger),
			"COMMIT_GROUP_MAX_ENTRIES" => Ok(Self::CommitGroupMaxEntries),
			"TOMBSTONE_REAP_INTERVAL" => Ok(Self::TombstoneReapInterval),
			"TOMBSTONE_REAP_BATCH_SIZE" => Ok(Self::TombstoneReapBatchSize),
			_ => Err(format!("Unknown system configuration key: {}", s)),
		}
	}
}

#[derive(Debug, Clone)]
pub struct Config {
	pub key: ConfigKey,

	pub value: Value,

	pub default_value: Value,

	pub description: &'static str,

	pub requires_restart: bool,
}

pub trait GetConfig: Send + Sync {
	fn get_config(&self, key: ConfigKey) -> Value;

	fn get_config_at(&self, key: ConfigKey, version: CommitVersion) -> Value;

	fn get_config_uint8(&self, key: ConfigKey) -> u64 {
		let val = self.get_config(key);
		match val {
			Value::Uint8(v) => v,
			v => panic!("config key '{}' expected Uint8, got {:?}", key, v),
		}
	}

	fn get_config_uint1(&self, key: ConfigKey) -> u8 {
		let val = self.get_config(key);
		match val {
			Value::Uint1(v) => v,
			v => panic!("config key '{}' expected Uint1, got {:?}", key, v),
		}
	}

	fn get_config_uint2(&self, key: ConfigKey) -> u16 {
		let val = self.get_config(key);
		match val {
			Value::Uint2(v) => v,
			v => panic!("config key '{}' expected Uint2, got {:?}", key, v),
		}
	}

	fn get_config_duration(&self, key: ConfigKey) -> Duration {
		let val = self.get_config(key);
		match val {
			Value::Duration(v) => v,
			v => panic!("config key '{}' expected Duration, got {:?}", key, v),
		}
	}

	fn get_config_duration_opt(&self, key: ConfigKey) -> Option<Duration> {
		match self.get_config(key) {
			Value::None {
				..
			} => None,
			Value::Duration(v) => Some(v),
			v => panic!("config key '{}' expected Duration or None, got {:?}", key, v),
		}
	}

	fn get_config_uint8_opt(&self, key: ConfigKey) -> Option<u64> {
		match self.get_config(key) {
			Value::None {
				..
			} => None,
			Value::Uint8(v) => Some(v),
			v => panic!("config key '{}' expected Uint8 or None, got {:?}", key, v),
		}
	}
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn test_cdc_ttl_default_is_typed_null() {
		// Defaulting to Value::None means "TTL not configured" - producer skips cleanup.
		let default = ConfigKey::CdcTtlDuration.default_value();
		assert!(matches!(
			default,
			Value::None {
				inner: ValueType::Duration
			}
		));
	}

	#[test]
	fn test_cdc_ttl_accept_passes_typed_null() {
		let none = Value::None {
			inner: ValueType::Duration,
		};
		let v = ConfigKey::CdcTtlDuration.accept(none.clone()).unwrap();
		assert_eq!(v, none);
	}

	#[test]
	fn test_cdc_ttl_accept_passes_positive_duration() {
		let one_sec = Value::duration_seconds(1);
		assert_eq!(ConfigKey::CdcTtlDuration.accept(one_sec.clone()).unwrap(), one_sec);

		let one_hour = Value::duration_seconds(3600);
		assert_eq!(ConfigKey::CdcTtlDuration.accept(one_hour.clone()).unwrap(), one_hour);
	}

	#[test]
	fn test_cdc_ttl_accept_rejects_zero() {
		let zero = Value::duration_seconds(0);
		match ConfigKey::CdcTtlDuration.accept(zero).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_cdc_ttl_accept_rejects_negative() {
		let negative = Value::duration_seconds(-5);
		assert!(matches!(ConfigKey::CdcTtlDuration.accept(negative), Err(AcceptError::InvalidValue(_))));
	}

	#[test]
	fn test_other_keys_accept_in_type_values() {
		assert!(ConfigKey::OracleWindowSize.accept(Value::Uint8(0)).is_ok());
	}

	#[test]
	fn test_cdc_ttl_round_trips_through_display_and_from_str() {
		let key: ConfigKey = "CDC_TTL_DURATION".parse().unwrap();
		assert_eq!(key, ConfigKey::CdcTtlDuration);
		assert_eq!(format!("{}", ConfigKey::CdcTtlDuration), "CDC_TTL_DURATION");
	}

	#[test]
	fn test_cdc_ttl_in_all() {
		assert!(ConfigKey::all().contains(&ConfigKey::CdcTtlDuration));
	}

	#[test]
	fn test_query_memory_limit_defaults_and_round_trips() {
		assert_eq!(ConfigKey::QueryMemoryLimit.default_value(), Value::Uint8(1024 * 1024 * 1024));
		assert_eq!(ConfigKey::QueryMemoryLimit.expected_types(), &[ValueType::Uint8]);
		let key: ConfigKey = "QUERY_MEMORY_LIMIT".parse().unwrap();
		assert_eq!(key, ConfigKey::QueryMemoryLimit);
		assert_eq!(format!("{}", ConfigKey::QueryMemoryLimit), "QUERY_MEMORY_LIMIT");
	}

	#[test]
	fn test_query_memory_limit_rejects_zero() {
		// A zero budget would reject every query, including trivial ones, so it must not be settable.
		assert!(ConfigKey::QueryMemoryLimit.accept(Value::Uint8(0)).is_err());
		assert_eq!(ConfigKey::QueryMemoryLimit.accept(Value::Uint8(1)).unwrap(), Value::Uint8(1));
	}

	#[test]
	fn test_query_memory_limit_requires_restart_and_optional() {
		// Read fresh for each query, so a live change takes effect immediately.
		assert!(!ConfigKey::QueryMemoryLimit.requires_restart());
		// Always defaulted to 1 GiB, never unset.
		assert!(!ConfigKey::QueryMemoryLimit.is_optional());
	}

	#[test]
	fn test_all_contains_every_compact_key_and_has_expected_len() {
		let all = ConfigKey::all();
		assert_eq!(all.len(), 47);
		assert!(all.contains(&ConfigKey::QueryMemoryLimit));
		assert!(all.contains(&ConfigKey::CommitGroupLinger));
		assert!(all.contains(&ConfigKey::CommitGroupMaxEntries));
		assert!(all.contains(&ConfigKey::RetentionEvictInterval));
		assert!(all.contains(&ConfigKey::RetentionEvictBatchSize));
		assert!(all.contains(&ConfigKey::RetentionEvictMaxBatchesPerTick));
		assert!(all.contains(&ConfigKey::MultiFlushInterval));
		assert!(all.contains(&ConfigKey::MultiWalAutocheckpoint));
		assert!(all.contains(&ConfigKey::CdcWalAutocheckpoint));
		assert!(all.contains(&ConfigKey::CdcConsumeWaitTimeout));
		assert!(all.contains(&ConfigKey::FlowJoinProbeBlockSize));
		assert!(all.contains(&ConfigKey::CdcTtlScanInterval));
		assert!(all.contains(&ConfigKey::CdcTtlScanBatchSize));
		assert!(all.contains(&ConfigKey::CdcCompactInterval));
		assert!(all.contains(&ConfigKey::CdcCompactBlockSize));
		assert!(all.contains(&ConfigKey::CdcCompactSafetyLag));
		assert!(all.contains(&ConfigKey::CdcCompactMaxBlocksPerTick));
		assert!(all.contains(&ConfigKey::CdcCompactBlockCacheCapacity));
		assert!(all.contains(&ConfigKey::CdcCompactZstdLevel));
		assert!(all.contains(&ConfigKey::MultiReadBufferPages));
		assert!(all.contains(&ConfigKey::FlowBacklogMemoryLimit));
		assert!(all.contains(&ConfigKey::FlowPullBatchBytes));
		assert!(all.contains(&ConfigKey::FlowLoadBatchBytes));
		assert!(all.contains(&ConfigKey::MultiReadBufferPageSize));
		assert!(all.contains(&ConfigKey::QueryRowBatchSize));
		assert!(all.contains(&ConfigKey::ThreadsAsync));
		assert!(all.contains(&ConfigKey::ThreadsCoordination));
		assert!(all.contains(&ConfigKey::ThreadsFlow));
		assert!(all.contains(&ConfigKey::ThreadsTask));
		assert!(all.contains(&ConfigKey::ThreadsCompute));
		assert!(all.contains(&ConfigKey::MetricsFlushInterval));
		assert!(all.contains(&ConfigKey::SubscriptionWorkerThreads));
		assert!(all.contains(&ConfigKey::FlowSampleInterval));
		assert!(all.contains(&ConfigKey::MetricsSampleInterval));
		assert!(all.contains(&ConfigKey::MetricsSnapshotInterval));
	}

	#[test]
	fn test_metrics_sample_interval_is_always_on() {
		// Sampling is the one path that populates every ::current; an off value would let a
		// domain go silently unsampled, which is exactly the failure the redesign removed.
		assert_eq!(ConfigKey::MetricsSampleInterval.default_value(), Value::duration_seconds(10));
		assert_eq!(ConfigKey::MetricsSampleInterval.expected_types(), &[ValueType::Duration]);
		assert!(!ConfigKey::MetricsSampleInterval.is_optional(), "there is no off value, only a cadence");
		assert!(ConfigKey::MetricsSampleInterval.requires_restart(), "read once at boot");

		let ten = Value::duration_seconds(10);
		assert_eq!(ConfigKey::MetricsSampleInterval.accept(ten.clone()).unwrap(), ten);
		let zero = Value::duration_seconds(0);
		assert!(matches!(ConfigKey::MetricsSampleInterval.accept(zero), Err(AcceptError::InvalidValue(_))));
	}

	#[test]
	fn test_metrics_snapshot_interval_accepts_none_and_positive_rejects_zero() {
		// none means snapshotting is off entirely; zero would write duplicate rows forever.
		assert_eq!(
			ConfigKey::MetricsSnapshotInterval.default_value(),
			Value::None {
				inner: ValueType::Duration
			},
			"snapshotting must be opt-in"
		);
		assert!(ConfigKey::MetricsSnapshotInterval.is_optional(), "none must stay accepted to turn it off");
		assert!(ConfigKey::MetricsSnapshotInterval.requires_restart(), "read once at boot");

		let none = Value::None {
			inner: ValueType::Duration,
		};
		assert_eq!(ConfigKey::MetricsSnapshotInterval.accept(none.clone()).unwrap(), none);

		let minute = Value::duration_seconds(60);
		assert_eq!(ConfigKey::MetricsSnapshotInterval.accept(minute.clone()).unwrap(), minute);

		let zero = Value::duration_seconds(0);
		match ConfigKey::MetricsSnapshotInterval.accept(zero).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("must be greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_metrics_sampler_keys_round_trip() {
		for (key, name) in [
			(ConfigKey::MetricsSampleInterval, "METRICS_SAMPLE_INTERVAL"),
			(ConfigKey::MetricsSnapshotInterval, "METRICS_SNAPSHOT_INTERVAL"),
		] {
			assert_eq!(format!("{key}"), name);
			assert_eq!(name.parse::<ConfigKey>().unwrap(), key);
		}
	}

	#[test]
	fn test_flow_sample_interval_metadata() {
		// Optional Duration knob: defaults on at once-a-minute; none disables
		// per-operator sampling entirely.
		assert_eq!(ConfigKey::FlowSampleInterval.default_value(), Value::duration_seconds(60));
		assert_eq!(ConfigKey::FlowSampleInterval.expected_types(), &[ValueType::Duration]);
		assert!(ConfigKey::FlowSampleInterval.is_optional());
	}

	#[test]
	fn test_flow_sample_interval_round_trip() {
		assert_eq!("FLOW_SAMPLE_INTERVAL".parse::<ConfigKey>().unwrap(), ConfigKey::FlowSampleInterval);
		assert_eq!(format!("{}", ConfigKey::FlowSampleInterval), "FLOW_SAMPLE_INTERVAL");
	}

	#[test]
	fn test_flow_sample_interval_accepts_none_and_positive_rejects_zero() {
		let none = Value::None {
			inner: ValueType::Duration,
		};
		assert_eq!(
			ConfigKey::FlowSampleInterval.accept(none.clone()).unwrap(),
			none,
			"none must be accepted so sampling can be turned off"
		);

		let minute = Value::duration_seconds(60);
		assert_eq!(ConfigKey::FlowSampleInterval.accept(minute.clone()).unwrap(), minute);

		let zero = Value::duration_seconds(0);
		assert!(matches!(ConfigKey::FlowSampleInterval.accept(zero), Err(AcceptError::InvalidValue(_))));
	}

	#[test]
	fn test_metrics_flush_interval_metadata() {
		// A non-optional Duration knob: there is no "off" value, only a cadence.
		assert_eq!(ConfigKey::MetricsFlushInterval.default_value(), Value::duration_seconds(10));
		assert_eq!(ConfigKey::MetricsFlushInterval.expected_types(), &[ValueType::Duration]);
		assert!(!ConfigKey::MetricsFlushInterval.is_optional());
		assert!(!ConfigKey::MetricsFlushInterval.requires_restart());
	}

	#[test]
	fn test_metrics_flush_interval_round_trip() {
		assert_eq!("METRICS_FLUSH_INTERVAL".parse::<ConfigKey>().unwrap(), ConfigKey::MetricsFlushInterval);
		assert_eq!(format!("{}", ConfigKey::MetricsFlushInterval), "METRICS_FLUSH_INTERVAL");
	}

	#[test]
	fn test_metrics_flush_interval_accepts_positive_rejects_zero() {
		let ten = Value::duration_seconds(10);
		assert_eq!(ConfigKey::MetricsFlushInterval.accept(ten.clone()).unwrap(), ten);

		let zero = Value::duration_seconds(0);
		assert!(matches!(ConfigKey::MetricsFlushInterval.accept(zero), Err(AcceptError::InvalidValue(_))));
	}

	#[test]
	fn test_multi_read_buffer_pages_round_trip() {
		assert_eq!("MULTI_READ_BUFFER_PAGES".parse::<ConfigKey>().unwrap(), ConfigKey::MultiReadBufferPages);
		assert_eq!(format!("{}", ConfigKey::MultiReadBufferPages), "MULTI_READ_BUFFER_PAGES");
	}

	#[test]
	fn test_multi_read_buffer_pages_metadata_and_rejects_zero() {
		assert_eq!(ConfigKey::MultiReadBufferPages.default_value(), Value::Uint8(1024));
		assert_eq!(ConfigKey::MultiReadBufferPages.expected_types(), &[ValueType::Uint8]);
		assert!(ConfigKey::MultiReadBufferPages.requires_restart());
		assert!(!ConfigKey::MultiReadBufferPages.is_optional());
		match ConfigKey::MultiReadBufferPages.accept(Value::Uint8(0)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_multi_read_buffer_page_size_round_trip() {
		assert_eq!(
			"MULTI_READ_BUFFER_PAGE_SIZE".parse::<ConfigKey>().unwrap(),
			ConfigKey::MultiReadBufferPageSize
		);
		assert_eq!(format!("{}", ConfigKey::MultiReadBufferPageSize), "MULTI_READ_BUFFER_PAGE_SIZE");
	}

	#[test]
	fn test_multi_read_buffer_page_size_metadata_and_rejects_non_power_of_two() {
		// Page size must be a power of two because pages are addressed by a row-number bit shift
		// (bucket = row >> shift); a non-power-of-two would not map to a single shift.
		assert_eq!(ConfigKey::MultiReadBufferPageSize.default_value(), Value::Uint8(65536));
		assert_eq!(ConfigKey::MultiReadBufferPageSize.expected_types(), &[ValueType::Uint8]);
		assert!(ConfigKey::MultiReadBufferPageSize.requires_restart());
		assert!(!ConfigKey::MultiReadBufferPageSize.is_optional());
		assert_eq!(
			ConfigKey::MultiReadBufferPageSize.accept(Value::Uint8(4096)).unwrap(),
			Value::Uint8(4096),
			"a power-of-two page size is accepted"
		);
		match ConfigKey::MultiReadBufferPageSize.accept(Value::Uint8(1000)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("power of two"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_threads_keys_round_trip() {
		assert_eq!("THREADS_ASYNC".parse::<ConfigKey>().unwrap(), ConfigKey::ThreadsAsync);
		assert_eq!("THREADS_COORDINATION".parse::<ConfigKey>().unwrap(), ConfigKey::ThreadsCoordination);
		assert_eq!("THREADS_FLOW".parse::<ConfigKey>().unwrap(), ConfigKey::ThreadsFlow);
		assert_eq!("THREADS_TASK".parse::<ConfigKey>().unwrap(), ConfigKey::ThreadsTask);
		assert_eq!("THREADS_COMPUTE".parse::<ConfigKey>().unwrap(), ConfigKey::ThreadsCompute);
		assert_eq!(format!("{}", ConfigKey::ThreadsAsync), "THREADS_ASYNC");
		assert_eq!(format!("{}", ConfigKey::ThreadsCoordination), "THREADS_COORDINATION");
		assert_eq!(format!("{}", ConfigKey::ThreadsFlow), "THREADS_FLOW");
		assert_eq!(format!("{}", ConfigKey::ThreadsTask), "THREADS_TASK");
		assert_eq!(format!("{}", ConfigKey::ThreadsCompute), "THREADS_COMPUTE");
	}

	#[test]
	fn test_threads_defaults() {
		assert_eq!(ConfigKey::ThreadsAsync.default_value(), Value::Uint2(1));
		assert_eq!(ConfigKey::ThreadsCoordination.default_value(), Value::Uint2(2));
		assert_eq!(ConfigKey::ThreadsFlow.default_value(), Value::Uint2(2));
		assert_eq!(ConfigKey::ThreadsTask.default_value(), Value::Uint2(2));
		assert_eq!(ConfigKey::ThreadsCompute.default_value(), Value::Uint2(2));
	}

	#[test]
	fn test_threads_reject_zero() {
		for key in [
			ConfigKey::ThreadsAsync,
			ConfigKey::ThreadsCoordination,
			ConfigKey::ThreadsFlow,
			ConfigKey::ThreadsTask,
			ConfigKey::ThreadsCompute,
		] {
			match key.accept(Value::Uint2(0)).unwrap_err() {
				AcceptError::InvalidValue(reason) => {
					assert!(
						reason.contains("greater than zero"),
						"{key}: unexpected reason: {reason}"
					);
				}
				other => panic!("{key}: expected InvalidValue, got {other:?}"),
			}
		}
	}

	#[test]
	fn test_threads_accept_positive() {
		assert_eq!(ConfigKey::ThreadsAsync.accept(Value::Uint2(4)).unwrap(), Value::Uint2(4));
		assert_eq!(ConfigKey::ThreadsCoordination.accept(Value::Uint2(8)).unwrap(), Value::Uint2(8));
		assert_eq!(ConfigKey::ThreadsFlow.accept(Value::Uint2(16)).unwrap(), Value::Uint2(16));
		assert_eq!(ConfigKey::ThreadsTask.accept(Value::Uint2(4)).unwrap(), Value::Uint2(4));
		assert_eq!(ConfigKey::ThreadsCompute.accept(Value::Uint2(2)).unwrap(), Value::Uint2(2));
	}

	#[test]
	fn test_threads_reject_int4_for_uint2_key() {
		// accept is strict: coercion happens at the CALL boundary via cast_value.
		assert!(matches!(ConfigKey::ThreadsTask.accept(Value::Int4(8)), Err(AcceptError::TypeMismatch { .. })));
	}

	#[test]
	fn test_threads_require_restart() {
		assert!(ConfigKey::ThreadsAsync.requires_restart());
		assert!(ConfigKey::ThreadsCoordination.requires_restart());
		assert!(ConfigKey::ThreadsFlow.requires_restart());
		assert!(ConfigKey::ThreadsTask.requires_restart());
		assert!(ConfigKey::ThreadsCompute.requires_restart());
	}

	#[test]
	fn test_query_row_batch_size_default_is_uint2_128() {
		assert_eq!(ConfigKey::QueryRowBatchSize.default_value(), Value::Uint2(128));
	}

	#[test]
	fn test_query_row_batch_size_round_trips_through_display_and_from_str() {
		let key: ConfigKey = "QUERY_ROW_BATCH_SIZE".parse().unwrap();
		assert_eq!(key, ConfigKey::QueryRowBatchSize);
		assert_eq!(format!("{}", ConfigKey::QueryRowBatchSize), "QUERY_ROW_BATCH_SIZE");
	}

	#[test]
	fn test_query_row_batch_size_accept_rejects_zero() {
		match ConfigKey::QueryRowBatchSize.accept(Value::Uint2(0)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_query_row_batch_size_accept_passes_positive() {
		assert_eq!(ConfigKey::QueryRowBatchSize.accept(Value::Uint2(1)).unwrap(), Value::Uint2(1));
		assert_eq!(ConfigKey::QueryRowBatchSize.accept(Value::Uint2(1024)).unwrap(), Value::Uint2(1024));
	}

	#[test]
	fn test_query_row_batch_size_rejects_mismatched_type() {
		// accept is strict: an Int4 no longer coerces here, regardless of the value.
		assert!(matches!(
			ConfigKey::QueryRowBatchSize.accept(Value::Int4(64)),
			Err(AcceptError::TypeMismatch { .. })
		));
		assert!(matches!(
			ConfigKey::QueryRowBatchSize.accept(Value::Int4(0)),
			Err(AcceptError::TypeMismatch { .. })
		));
	}

	#[test]
	fn test_cdc_compact_interval_round_trips_through_display_and_from_str() {
		let key: ConfigKey = "CDC_COMPACT_INTERVAL".parse().unwrap();
		assert_eq!(key, ConfigKey::CdcCompactInterval);
		assert_eq!(format!("{}", ConfigKey::CdcCompactInterval), "CDC_COMPACT_INTERVAL");
	}

	#[test]
	fn test_cdc_compact_block_size_round_trips_through_display_and_from_str() {
		let key: ConfigKey = "CDC_COMPACT_BLOCK_SIZE".parse().unwrap();
		assert_eq!(key, ConfigKey::CdcCompactBlockSize);
		assert_eq!(format!("{}", ConfigKey::CdcCompactBlockSize), "CDC_COMPACT_BLOCK_SIZE");
	}

	#[test]
	fn test_cdc_compact_safety_lag_round_trips_through_display_and_from_str() {
		let key: ConfigKey = "CDC_COMPACT_SAFETY_LAG".parse().unwrap();
		assert_eq!(key, ConfigKey::CdcCompactSafetyLag);
		assert_eq!(format!("{}", ConfigKey::CdcCompactSafetyLag), "CDC_COMPACT_SAFETY_LAG");
	}

	#[test]
	fn test_cdc_compact_max_blocks_per_tick_round_trips_through_display_and_from_str() {
		let key: ConfigKey = "CDC_COMPACT_MAX_BLOCKS_PER_TICK".parse().unwrap();
		assert_eq!(key, ConfigKey::CdcCompactMaxBlocksPerTick);
		assert_eq!(format!("{}", ConfigKey::CdcCompactMaxBlocksPerTick), "CDC_COMPACT_MAX_BLOCKS_PER_TICK");
	}

	#[test]
	fn test_cdc_compact_interval_default_is_duration() {
		assert!(matches!(ConfigKey::CdcCompactInterval.default_value(), Value::Duration(_)));
	}

	#[test]
	fn test_cdc_compact_block_size_default_is_uint8_1024() {
		assert_eq!(ConfigKey::CdcCompactBlockSize.default_value(), Value::Uint8(1024));
	}

	#[test]
	fn test_cdc_compact_safety_lag_default_is_uint8_1024() {
		assert_eq!(ConfigKey::CdcCompactSafetyLag.default_value(), Value::Uint8(1024));
	}

	#[test]
	fn test_cdc_compact_max_blocks_per_tick_default_is_uint8_16() {
		assert_eq!(ConfigKey::CdcCompactMaxBlocksPerTick.default_value(), Value::Uint8(16));
	}

	#[test]
	fn test_cdc_compact_interval_accept_passes_positive_duration() {
		let one_sec = Value::duration_seconds(1);
		assert_eq!(ConfigKey::CdcCompactInterval.accept(one_sec.clone()).unwrap(), one_sec);
	}

	#[test]
	fn test_cdc_compact_interval_accept_rejects_zero() {
		let zero = Value::duration_seconds(0);
		match ConfigKey::CdcCompactInterval.accept(zero).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_cdc_compact_interval_accept_rejects_negative() {
		let negative = Value::duration_seconds(-5);
		assert!(matches!(ConfigKey::CdcCompactInterval.accept(negative), Err(AcceptError::InvalidValue(_))));
	}

	#[test]
	fn test_cdc_compact_block_size_accept_rejects_zero() {
		match ConfigKey::CdcCompactBlockSize.accept(Value::Uint8(0)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_cdc_compact_block_size_accept_passes_positive() {
		assert_eq!(ConfigKey::CdcCompactBlockSize.accept(Value::Uint8(1)).unwrap(), Value::Uint8(1));
		assert_eq!(ConfigKey::CdcCompactBlockSize.accept(Value::Uint8(1024)).unwrap(), Value::Uint8(1024));
	}

	#[test]
	fn test_cdc_compact_safety_lag_and_max_blocks_accept_zero() {
		assert_eq!(ConfigKey::CdcCompactSafetyLag.accept(Value::Uint8(0)).unwrap(), Value::Uint8(0));
		assert_eq!(ConfigKey::CdcCompactMaxBlocksPerTick.accept(Value::Uint8(0)).unwrap(), Value::Uint8(0));
	}

	#[test]
	fn test_accept_rejects_int4_for_uint8_block_size() {
		// accept is strict: SET CONFIG casts to Uint8 via cast_value before calling accept.
		assert!(matches!(
			ConfigKey::CdcCompactBlockSize.accept(Value::Int4(1024)),
			Err(AcceptError::TypeMismatch { .. })
		));
		assert!(matches!(
			ConfigKey::CdcCompactBlockSize.accept(Value::Int8(2048)),
			Err(AcceptError::TypeMismatch { .. })
		));
	}

	#[test]
	fn test_accept_rejects_zero_of_canonical_type() {
		match ConfigKey::CdcCompactBlockSize.accept(Value::Uint8(0)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"));
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_accept_rejects_negative_int_for_uint8_key() {
		// accept is strict on type, so an Int4 is refused before its value is ever inspected; the
		// sign is incidental.
		assert!(matches!(
			ConfigKey::CdcCompactBlockSize.accept(Value::Int4(-1)),
			Err(AcceptError::TypeMismatch { .. })
		));
	}

	#[test]
	fn test_accept_rejects_int_for_duration_key() {
		// Bare integers carry no unit: duration keys take Duration values (or duration
		// strings cast at the CALL boundary), never int-as-seconds.
		assert!(matches!(
			ConfigKey::CdcCompactInterval.accept(Value::Int4(60)),
			Err(AcceptError::TypeMismatch { .. })
		));
	}

	#[test]
	fn test_accept_idempotent_on_canonical_uint8() {
		let canonical = Value::Uint8(42);
		assert_eq!(ConfigKey::OracleWindowSize.accept(canonical.clone()).unwrap(), canonical);
	}

	#[test]
	fn test_accept_idempotent_on_canonical_duration() {
		let canonical = Value::duration_seconds(5);
		assert_eq!(ConfigKey::CdcCompactInterval.accept(canonical.clone()).unwrap(), canonical);
	}

	#[test]
	fn test_accept_rejects_typed_null_for_non_optional_key() {
		let err = ConfigKey::CdcCompactBlockSize
			.accept(Value::None {
				inner: ValueType::Uint8,
			})
			.unwrap_err();
		assert!(matches!(err, AcceptError::TypeMismatch { .. }));
	}

	#[test]
	fn test_accept_passes_typed_null_for_optional_key() {
		let none = Value::None {
			inner: ValueType::Duration,
		};
		assert_eq!(ConfigKey::CdcTtlDuration.accept(none.clone()).unwrap(), none);
	}

	#[test]
	fn test_accept_rejects_wrong_inner_type_typed_null_for_optional_key() {
		// Optional key still rejects typed-null whose inner doesn't match expected_types.
		let err = ConfigKey::CdcTtlDuration
			.accept(Value::None {
				inner: ValueType::Uint8,
			})
			.unwrap_err();
		assert!(matches!(err, AcceptError::TypeMismatch { .. }));
	}

	#[test]
	fn test_commit_group_linger_default_is_none() {
		// Group commit is opt-in: leaving this key untouched must keep every unchecked commit on
		// its own transaction and version. Grouping is enabled by setting a positive linger.
		assert_eq!(
			ConfigKey::CommitGroupLinger.default_value(),
			Value::None {
				inner: ValueType::Duration,
			}
		);
		assert!(ConfigKey::CommitGroupLinger.is_optional());
		assert_eq!(ConfigKey::CommitGroupLinger.expected_types(), &[ValueType::Duration]);
	}

	#[test]
	fn test_commit_group_linger_accepts_none_to_disable_grouping() {
		let none = Value::None {
			inner: ValueType::Duration,
		};
		assert_eq!(ConfigKey::CommitGroupLinger.accept(none.clone()).unwrap(), none);
	}

	#[test]
	fn test_commit_group_linger_rejects_zero_and_negative() {
		// A zero linger arms a fire-immediately timer for every submission and a negative one
		// cannot schedule at all; "disabled" is expressed by absence, so zero must be rejected.
		match ConfigKey::CommitGroupLinger.accept(Value::duration_seconds(0)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
		assert!(matches!(
			ConfigKey::CommitGroupLinger.accept(Value::duration_seconds(-5)),
			Err(AcceptError::InvalidValue(_))
		));
	}

	#[test]
	fn test_commit_group_linger_requires_restart() {
		// The coordinator is spawned (or not) once at database construction and never re-reads
		// this key, so a live change would silently have no effect.
		assert!(ConfigKey::CommitGroupLinger.requires_restart());
	}

	#[test]
	fn test_commit_group_linger_round_trips_through_display_and_from_str() {
		assert_eq!("COMMIT_GROUP_LINGER".parse::<ConfigKey>().unwrap(), ConfigKey::CommitGroupLinger);
		assert_eq!(format!("{}", ConfigKey::CommitGroupLinger), "COMMIT_GROUP_LINGER");
	}

	#[test]
	fn test_commit_group_max_entries_metadata() {
		assert_eq!(ConfigKey::CommitGroupMaxEntries.default_value(), Value::Uint8(256));
		assert_eq!(ConfigKey::CommitGroupMaxEntries.expected_types(), &[ValueType::Uint8]);
		assert!(!ConfigKey::CommitGroupMaxEntries.is_optional());
		assert!(ConfigKey::CommitGroupMaxEntries.requires_restart());
	}

	#[test]
	fn test_commit_group_max_entries_rejects_zero() {
		// A zero bound would flush every group before it could accept a single submission,
		// deadlocking every commit behind a group that can never fill.
		match ConfigKey::CommitGroupMaxEntries.accept(Value::Uint8(0)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
		assert_eq!(ConfigKey::CommitGroupMaxEntries.accept(Value::Uint8(1)).unwrap(), Value::Uint8(1));
	}

	#[test]
	fn test_commit_group_max_entries_round_trips_through_display_and_from_str() {
		assert_eq!("COMMIT_GROUP_MAX_ENTRIES".parse::<ConfigKey>().unwrap(), ConfigKey::CommitGroupMaxEntries);
		assert_eq!(format!("{}", ConfigKey::CommitGroupMaxEntries), "COMMIT_GROUP_MAX_ENTRIES");
	}

	#[test]
	fn test_historical_gc_keys_round_trip() {
		assert_eq!("HISTORICAL_GC_BATCH_SIZE".parse::<ConfigKey>().unwrap(), ConfigKey::HistoricalGcBatchSize);
		assert_eq!("HISTORICAL_GC_INTERVAL".parse::<ConfigKey>().unwrap(), ConfigKey::HistoricalGcInterval);
		assert_eq!(format!("{}", ConfigKey::HistoricalGcBatchSize), "HISTORICAL_GC_BATCH_SIZE");
		assert_eq!(format!("{}", ConfigKey::HistoricalGcInterval), "HISTORICAL_GC_INTERVAL");
	}

	#[test]
	fn test_historical_gc_defaults() {
		assert_eq!(ConfigKey::HistoricalGcBatchSize.default_value(), Value::Uint8(50_000));
		assert!(matches!(ConfigKey::HistoricalGcInterval.default_value(), Value::Duration(_)));
	}

	#[test]
	fn test_historical_gc_batch_size_rejects_zero() {
		match ConfigKey::HistoricalGcBatchSize.accept(Value::Uint8(0)).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}

	#[test]
	fn test_historical_gc_interval_rejects_zero() {
		let zero = Value::duration_seconds(0);
		match ConfigKey::HistoricalGcInterval.accept(zero).unwrap_err() {
			AcceptError::InvalidValue(reason) => {
				assert!(reason.contains("greater than zero"), "unexpected reason: {reason}");
			}
			other => panic!("expected InvalidValue, got {other:?}"),
		}
	}
}