fsqlite-wal 0.1.13

Write-ahead logging
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
use std::fmt::Write as _;
use std::fs;
use std::path::Path;
use std::process::Command;
use std::time::Instant;

use fsqlite_wal::checksum::{
    HashTier, SQLITE_DB_HEADER_RESERVED_OFFSET, SQLITE_DB_HEADER_SIZE, WAL_FRAME_HEADER_SIZE,
    WAL_HEADER_SIZE, WalChainInvalidReason, WalSalts, Xxh3Checksum128,
    configure_page_checksum_reserved_bytes, content_address_hash_128, crc32c_checksum,
    integrity_check_level1_page, integrity_check_level2_btree,
    integrity_check_level3_overflow_chain, integrity_check_level4_cross_reference,
    integrity_check_level5_schema, integrity_check_sqlite_file_level1, merge_integrity_reports,
    page_checksum_reserved_bytes, read_page_checksum, sqlite_wal_checksum, tier_for_algorithm,
    validate_wal_chain, verify_page_checksum, verify_wal_fec_source_hash,
    wal_fec_source_hash_xxh3_128, write_page_checksum, write_wal_frame_checksum,
    write_wal_frame_salts, write_wal_header_checksum, write_wal_header_salts,
    zero_page_checksum_trailer,
};
use tempfile::tempdir;

const BEAD_30B5_ID: &str = "bd-30b5";
const BEAD_3I98_ID: &str = "bd-3i98";
const PAGE_SIZE: usize = 4096;
const FRAME_SIZE: usize = WAL_FRAME_HEADER_SIZE + PAGE_SIZE;
const PAGE_RESERVED_U8: u8 = 16;
const BIG_END_CKSUM: bool = false;

struct WalFixture {
    wal_header: [u8; WAL_HEADER_SIZE],
    frame_bytes: Vec<u8>,
    source_hashes: Vec<Xxh3Checksum128>,
}

fn sample_payload(seed: u8) -> [u8; PAGE_SIZE] {
    let mut payload = [0_u8; PAGE_SIZE];
    for (index, byte) in payload.iter_mut().enumerate() {
        let reduced_index = u8::try_from(index % 251).expect("modulo result must fit in u8");
        *byte = reduced_index ^ seed;
    }
    payload
}

fn sample_btree_leaf_page() -> [u8; PAGE_SIZE] {
    let mut page = [0_u8; PAGE_SIZE];
    page[0] = 0x0D; // leaf table page
    page[1..3].copy_from_slice(&0_u16.to_be_bytes());
    page[3..5].copy_from_slice(&0_u16.to_be_bytes());
    page[5..7].copy_from_slice(
        &u16::try_from(PAGE_SIZE)
            .expect("PAGE_SIZE should fit in u16 for test")
            .to_be_bytes(),
    );
    page[7] = 0;
    page
}

fn frame_offset(frame_index: usize) -> usize {
    frame_index * FRAME_SIZE
}

fn frame_payload_slice(frame_bytes: &[u8], frame_index: usize) -> &[u8] {
    let start = frame_offset(frame_index) + WAL_FRAME_HEADER_SIZE;
    let end = frame_offset(frame_index) + FRAME_SIZE;
    &frame_bytes[start..end]
}

fn wal_bytes(wal_header: &[u8; WAL_HEADER_SIZE], frame_bytes: &[u8]) -> Vec<u8> {
    let mut bytes = Vec::with_capacity(WAL_HEADER_SIZE + frame_bytes.len());
    bytes.extend_from_slice(wal_header);
    bytes.extend_from_slice(frame_bytes);
    bytes
}

fn build_wal(db_sizes: &[u32], salts: WalSalts) -> WalFixture {
    let mut wal_header = [0_u8; WAL_HEADER_SIZE];
    wal_header[..4].copy_from_slice(&0x377F_0682_u32.to_be_bytes());
    wal_header[4..8].copy_from_slice(&3_007_000_u32.to_be_bytes());
    wal_header[8..12].copy_from_slice(
        &u32::try_from(PAGE_SIZE)
            .expect("PAGE_SIZE must fit in u32")
            .to_be_bytes(),
    );
    write_wal_header_salts(&mut wal_header, salts).expect("header salts should be writable");

    let mut rolling_checksum = write_wal_header_checksum(&mut wal_header, BIG_END_CKSUM)
        .expect("header checksum should write");

    let mut frame_bytes = Vec::with_capacity(db_sizes.len() * FRAME_SIZE);
    let mut source_hashes = Vec::with_capacity(db_sizes.len());

    for (frame_index, db_size) in db_sizes.iter().copied().enumerate() {
        let mut frame = vec![0_u8; FRAME_SIZE];
        let (frame_header, frame_page) = frame.split_at_mut(WAL_FRAME_HEADER_SIZE);

        let page_number = u32::try_from(frame_index + 1).expect("frame index must fit in u32");
        frame_header[..4].copy_from_slice(&page_number.to_be_bytes());
        frame_header[4..8].copy_from_slice(&db_size.to_be_bytes());
        write_wal_frame_salts(frame_header, salts).expect("frame salts should write");

        let seed = u8::try_from((frame_index % 250) + 1).expect("frame seed must fit in u8");
        let payload = sample_payload(seed);
        frame_page.copy_from_slice(&payload);
        source_hashes.push(wal_fec_source_hash_xxh3_128(&payload));

        rolling_checksum =
            write_wal_frame_checksum(&mut frame, PAGE_SIZE, rolling_checksum, BIG_END_CKSUM)
                .expect("frame checksum should write");

        frame_bytes.extend_from_slice(&frame);
    }

    WalFixture {
        wal_header,
        frame_bytes,
        source_hashes,
    }
}

fn sqlite3_exec(db_path: &Path, sql: &str) -> std::process::Output {
    Command::new("sqlite3")
        .arg(db_path)
        .arg(sql)
        .output()
        .expect("sqlite3 command should execute")
}

fn normalize_sqlite_integrity_output(output: &std::process::Output) -> String {
    let stdout = String::from_utf8_lossy(&output.stdout);
    if output.status.success() && stdout.trim() == "ok" {
        "ok".to_owned()
    } else {
        "corrupt".to_owned()
    }
}

fn normalize_local_integrity_output(messages: &[String]) -> String {
    if messages.len() == 1 && messages[0] == "ok" {
        "ok".to_owned()
    } else {
        "corrupt".to_owned()
    }
}

#[test]
fn test_integrity_check_output_matches_c() {
    let temp_dir = tempdir().expect("tempdir should be created");
    let db_path = temp_dir.path().join("integrity_output_matches_c.db");
    let setup = sqlite3_exec(
        &db_path,
        "PRAGMA page_size=4096; CREATE TABLE t(x INTEGER); INSERT INTO t VALUES (1);",
    );
    assert!(
        setup.status.success(),
        "sqlite3 setup failed: {}",
        String::from_utf8_lossy(&setup.stderr)
    );

    let sqlite_report = sqlite3_exec(&db_path, "PRAGMA integrity_check;");
    assert!(
        sqlite_report.status.success(),
        "sqlite3 integrity_check failed: {}",
        String::from_utf8_lossy(&sqlite_report.stderr)
    );

    let db_bytes = fs::read(&db_path).expect("database file should be readable");
    let report =
        integrity_check_sqlite_file_level1(&db_bytes).expect("local integrity_check should run");

    assert_eq!(
        normalize_local_integrity_output(&report.sqlite_messages()),
        normalize_sqlite_integrity_output(&sqlite_report)
    );
    assert_eq!(normalize_sqlite_integrity_output(&sqlite_report), "ok");
}

#[test]
fn test_integrity_check_corrupt_output_parity_bad_header_magic() {
    let temp_dir = tempdir().expect("tempdir should be created");
    let db_path = temp_dir.path().join("integrity_corrupt_header.db");
    let setup = sqlite3_exec(
        &db_path,
        "PRAGMA page_size=4096; CREATE TABLE t(x INTEGER); INSERT INTO t VALUES (1);",
    );
    assert!(setup.status.success());

    let mut db_bytes = fs::read(&db_path).expect("database file should be readable");
    db_bytes[0] ^= 0x20;
    fs::write(&db_path, &db_bytes).expect("database file should be writable");

    let sqlite_report = sqlite3_exec(&db_path, "PRAGMA integrity_check;");
    let local_report =
        integrity_check_sqlite_file_level1(&db_bytes).expect("local integrity_check should run");

    assert_eq!(
        normalize_local_integrity_output(&local_report.sqlite_messages()),
        normalize_sqlite_integrity_output(&sqlite_report)
    );
    assert_eq!(normalize_sqlite_integrity_output(&sqlite_report), "corrupt");
}

#[test]
fn test_integrity_check_corrupt_output_parity_bad_btree_page_type() {
    let temp_dir = tempdir().expect("tempdir should be created");
    let db_path = temp_dir.path().join("integrity_corrupt_btree_type.db");
    let setup = sqlite3_exec(
        &db_path,
        "PRAGMA page_size=4096; CREATE TABLE t(x INTEGER); INSERT INTO t VALUES (1);",
    );
    assert!(setup.status.success());

    let mut db_bytes = fs::read(&db_path).expect("database file should be readable");
    let page_type_offset = SQLITE_DB_HEADER_SIZE;
    db_bytes[page_type_offset] = 0xFF;
    fs::write(&db_path, &db_bytes).expect("database file should be writable");

    let sqlite_report = sqlite3_exec(&db_path, "PRAGMA integrity_check;");
    let local_report =
        integrity_check_sqlite_file_level1(&db_bytes).expect("local integrity_check should run");

    assert_eq!(
        normalize_local_integrity_output(&local_report.sqlite_messages()),
        normalize_sqlite_integrity_output(&sqlite_report)
    );
    assert_eq!(normalize_sqlite_integrity_output(&sqlite_report), "corrupt");
}

#[test]
fn test_integrity_check_corrupt_output_parity_truncated_file() {
    let temp_dir = tempdir().expect("tempdir should be created");
    let db_path = temp_dir.path().join("integrity_corrupt_truncated.db");
    let setup = sqlite3_exec(
        &db_path,
        "PRAGMA page_size=4096; CREATE TABLE t(x INTEGER); INSERT INTO t VALUES (1);",
    );
    assert!(setup.status.success());

    let db_bytes = fs::read(&db_path).expect("database file should be readable");
    let truncated_len = SQLITE_DB_HEADER_SIZE + 24;
    let truncated = db_bytes[..truncated_len].to_vec();
    fs::write(&db_path, &truncated).expect("database file should be writable");

    let sqlite_report = sqlite3_exec(&db_path, "PRAGMA integrity_check;");
    let local_report =
        integrity_check_sqlite_file_level1(&truncated).expect("local integrity_check should run");

    assert_eq!(
        normalize_local_integrity_output(&local_report.sqlite_messages()),
        normalize_sqlite_integrity_output(&sqlite_report)
    );
    assert_eq!(normalize_sqlite_integrity_output(&sqlite_report), "corrupt");
}

#[test]
fn test_sqlite_native_checksum_compat() {
    let data = [
        0x10_u8, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80, 0x91, 0xA2, 0xB3, 0xC4, 0xD5, 0xE6,
        0xF7, 0x08,
    ];

    let little_endian =
        sqlite_wal_checksum(&data, 0, 0, false).expect("LE checksum should compute");
    let big_endian = sqlite_wal_checksum(&data, 0, 0, true).expect("BE checksum should compute");

    let little_endian_repeat =
        sqlite_wal_checksum(&data, 0, 0, false).expect("LE checksum recomputation should work");
    let big_endian_repeat =
        sqlite_wal_checksum(&data, 0, 0, true).expect("BE checksum recomputation should work");

    assert_eq!(
        little_endian.s1, 0xC584_4301,
        "bead_id={BEAD_30B5_ID} case=sqlite_checksum_le_s1"
    );
    assert_eq!(
        little_endian.s2, 0x8F1C_AA36,
        "bead_id={BEAD_30B5_ID} case=sqlite_checksum_le_s2"
    );
    assert_eq!(
        big_endian.s1, 0x0243_84C4,
        "bead_id={BEAD_30B5_ID} case=sqlite_checksum_be_s1"
    );
    assert_eq!(
        big_endian.s2, 0x38AB_1C8C,
        "bead_id={BEAD_30B5_ID} case=sqlite_checksum_be_s2"
    );
    assert_eq!(
        little_endian, little_endian_repeat,
        "bead_id={BEAD_30B5_ID} case=sqlite_checksum_le_deterministic"
    );
    assert_eq!(
        big_endian, big_endian_repeat,
        "bead_id={BEAD_30B5_ID} case=sqlite_checksum_be_deterministic"
    );
    assert_ne!(
        (little_endian.s1, little_endian.s2),
        (big_endian.s1, big_endian.s2),
        "bead_id={BEAD_30B5_ID} case=sqlite_checksum_endian_variant"
    );
}

#[test]
fn test_xxh3_round_trip() {
    let payload = b"frankensqlite-page-payload";
    let digest = Xxh3Checksum128::compute(payload);
    assert!(
        digest.verify(payload),
        "bead_id={BEAD_30B5_ID} case=xxh3_verify_original"
    );

    let mut tampered_payload = payload.to_vec();
    tampered_payload[0] ^= 0x80;
    assert!(
        !digest.verify(&tampered_payload),
        "bead_id={BEAD_30B5_ID} case=xxh3_detects_single_bit_flip"
    );
}

#[test]
fn test_crc32c_rfc_vectors() {
    let vector = b"123456789";
    assert_eq!(
        crc32c_checksum(vector),
        0xE306_9283,
        "bead_id={BEAD_30B5_ID} case=crc32c_rfc_vector"
    );
}

#[test]
fn test_three_tier_separation() {
    assert_eq!(tier_for_algorithm("xxh3_128"), Some(HashTier::Integrity));
    assert_eq!(
        tier_for_algorithm("blake3_128"),
        Some(HashTier::ContentAddressing)
    );
    assert_eq!(tier_for_algorithm("crc32c"), Some(HashTier::Protocol));
    assert_eq!(tier_for_algorithm("unknown"), None);

    let input = b"tiered-hash-input";
    let integrity_digest = Xxh3Checksum128::compute(input);
    let content_digest = content_address_hash_128(input);
    let protocol_digest = crc32c_checksum(input);

    assert!(
        integrity_digest.low != 0 || integrity_digest.high != 0,
        "bead_id={BEAD_30B5_ID} case=tier_integrity_nonzero_digest"
    );
    assert!(
        content_digest != [0_u8; 16],
        "bead_id={BEAD_30B5_ID} case=tier_content_nonzero_digest"
    );
    assert_ne!(
        protocol_digest, 0,
        "bead_id={BEAD_30B5_ID} case=tier_protocol_nonzero_crc"
    );
}

#[test]
fn test_hash_performance() {
    let block = [0xAB_u8; PAGE_SIZE];
    let rounds = 4096_u64;
    let block_len = u64::try_from(block.len()).expect("block length must fit in u64");
    let bytes_total = rounds * block_len;

    let start = Instant::now();
    let mut sink = 0_u64;
    for index in 0..rounds {
        let digest = Xxh3Checksum128::compute(&block);
        sink = sink.wrapping_add((digest.low ^ digest.high).wrapping_add(index));
    }
    let seconds = start.elapsed().as_secs_f64();
    let gigabytes_per_second = if seconds > 0.0 {
        (bytes_total as f64 / seconds) / 1_000_000_000.0
    } else {
        0.0
    };

    eprintln!(
        "bead_id={BEAD_30B5_ID} case=hash_perf xxh3_gbps={gigabytes_per_second:.2} sink={sink:#x}"
    );
    assert_ne!(
        sink, 0,
        "bead_id={BEAD_30B5_ID} case=hash_perf_sink_nonzero"
    );
}

#[test]
fn test_e2e_integrity_check_with_checksum_modes() {
    let salts = WalSalts {
        salt1: 0xA1A2_A3A4,
        salt2: 0xB1B2_B3B4,
    };
    let fixture = build_wal(&[1, 2, 3], salts);
    let valid_wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);

    let valid_chain =
        validate_wal_chain(&valid_wal_bytes, PAGE_SIZE, BIG_END_CKSUM).expect("valid chain");
    assert!(valid_chain.header_valid);
    assert_eq!(valid_chain.valid_frame_count, 3);

    let mut frame_corrupt = fixture.frame_bytes.clone();
    frame_corrupt[frame_offset(1) + WAL_FRAME_HEADER_SIZE + 128] ^= 0x01;
    let corrupted_wal_bytes = wal_bytes(&fixture.wal_header, &frame_corrupt);
    let chain_after_corrupt = validate_wal_chain(&corrupted_wal_bytes, PAGE_SIZE, BIG_END_CKSUM)
        .expect("corrupted chain");
    assert_eq!(chain_after_corrupt.first_invalid_frame, Some(1));
    assert_eq!(
        chain_after_corrupt.first_invalid_reason,
        Some(WalChainInvalidReason::FrameChecksumMismatch)
    );

    let mut page = sample_payload(11);
    write_page_checksum(&mut page).expect("page checksum should write");
    assert!(verify_page_checksum(&page).expect("page checksum should verify"));
    page[512] ^= 0x80;
    assert!(!verify_page_checksum(&page).expect("corrupted page checksum should fail"));
}

#[test]
fn test_page_checksum_xxh3_round_trip() {
    let mut page = sample_payload(17);
    let stored_checksum = write_page_checksum(&mut page).expect("page checksum should write");
    let read_back_checksum = read_page_checksum(&page).expect("page checksum should read");

    assert_eq!(stored_checksum, read_back_checksum);
    assert!(verify_page_checksum(&page).expect("page checksum should verify"));
}

#[test]
fn test_page_checksum_detect_corruption() {
    let mut page = sample_payload(21);
    write_page_checksum(&mut page).expect("page checksum should write");
    page[1234] ^= 0x01;
    assert!(!verify_page_checksum(&page).expect("corruption should be detected"));
}

#[test]
fn test_reserved_bytes_16() {
    let mut header = [0_u8; 100];
    configure_page_checksum_reserved_bytes(&mut header, true)
        .expect("header reserved-byte config should succeed");
    assert_eq!(header[SQLITE_DB_HEADER_RESERVED_OFFSET], PAGE_RESERVED_U8);
    assert_eq!(
        page_checksum_reserved_bytes(&header).expect("reserved byte read should succeed"),
        PAGE_RESERVED_U8
    );
}

#[test]
fn test_legacy_reads_reserved_ok() {
    let temp_dir = tempdir().expect("tempdir should be created");
    let db_path = temp_dir.path().join("legacy_read_reserved_ok.db");

    let create_output = sqlite3_exec(
        &db_path,
        "PRAGMA page_size=4096; CREATE TABLE t(x INTEGER); INSERT INTO t VALUES (1);",
    );
    assert!(
        create_output.status.success(),
        "sqlite3 setup failed: {}",
        String::from_utf8_lossy(&create_output.stderr)
    );

    let mut db_bytes = fs::read(&db_path).expect("database file should be readable");
    db_bytes[SQLITE_DB_HEADER_RESERVED_OFFSET] = PAGE_RESERVED_U8;
    fs::write(&db_path, db_bytes).expect("database file should be writable");

    let query_output = sqlite3_exec(&db_path, "SELECT COUNT(*) FROM t;");
    assert!(
        query_output.status.success(),
        "sqlite3 read failed: {}",
        String::from_utf8_lossy(&query_output.stderr)
    );
    assert_eq!(String::from_utf8_lossy(&query_output.stdout).trim(), "1");
}

#[test]
fn test_legacy_writes_invalidate_checksum() {
    let mut page = sample_payload(29);
    write_page_checksum(&mut page).expect("page checksum should write");
    assert!(verify_page_checksum(&page).expect("checksum should verify before legacy write"));

    zero_page_checksum_trailer(&mut page).expect("legacy zeroing should succeed");
    assert!(!verify_page_checksum(&page).expect("zeroed trailer should invalidate checksum"));
}

#[test]
fn test_wal_cumulative_chain_valid() {
    let salts = WalSalts {
        salt1: 0x1111_2222,
        salt2: 0x3333_4444,
    };
    let fixture = build_wal(&[1_u32; 100], salts);

    let wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);
    let validation =
        validate_wal_chain(&wal_bytes, PAGE_SIZE, BIG_END_CKSUM).expect("chain should validate");
    assert!(validation.valid);
    assert_eq!(validation.valid_frames, 100);
    assert_eq!(validation.replayable_frames, 100);
    assert_eq!(validation.first_invalid_frame, None);
    assert_eq!(validation.reason, None);
}

#[test]
fn test_wal_cumulative_chain_torn() {
    let salts = WalSalts {
        salt1: 0x1212_3434,
        salt2: 0x5656_7878,
    };
    let fixture = build_wal(&[1_u32; 100], salts);

    let torn_frame_index = 50;
    let torn_cut = frame_offset(torn_frame_index) + WAL_FRAME_HEADER_SIZE + PAGE_SIZE / 2;
    let torn_frames = fixture.frame_bytes[..torn_cut].to_vec();

    let torn_wal_bytes = wal_bytes(&fixture.wal_header, &torn_frames);
    let validation = validate_wal_chain(&torn_wal_bytes, PAGE_SIZE, BIG_END_CKSUM)
        .expect("torn chain should parse");
    assert_eq!(validation.valid_frames, 50);
    assert_eq!(validation.replayable_frames, 50);
    assert_eq!(validation.first_invalid_frame, Some(50));
    assert_eq!(
        validation.reason,
        Some(WalChainInvalidReason::TruncatedFrame)
    );
}

#[test]
fn test_wal_cumulative_chain_modified() {
    let salts = WalSalts {
        salt1: 0x0A0A_1B1B,
        salt2: 0x2C2C_3D3D,
    };
    let mut fixture = build_wal(&[1_u32; 100], salts);

    let modified_frame_index = 10;
    let corrupt_offset = frame_offset(modified_frame_index) + WAL_FRAME_HEADER_SIZE + 37;
    fixture.frame_bytes[corrupt_offset] ^= 0xFF;

    let wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);
    let validation = validate_wal_chain(&wal_bytes, PAGE_SIZE, BIG_END_CKSUM)
        .expect("modified chain should parse");
    assert_eq!(validation.valid_frames, 10);
    assert_eq!(validation.first_invalid_frame, Some(10));
    assert_eq!(
        validation.reason,
        Some(WalChainInvalidReason::FrameChecksumMismatch)
    );
}

#[test]
fn test_wal_recovery_truncation() {
    let salts = WalSalts {
        salt1: 0x0102_0304,
        salt2: 0x0506_0708,
    };
    let mut fixture = build_wal(&[1_u32; 40], salts);

    let first_invalid_frame = 30;
    let corrupt_offset = frame_offset(first_invalid_frame) + WAL_FRAME_HEADER_SIZE + 9;
    fixture.frame_bytes[corrupt_offset] ^= 0x10;

    let wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);
    let validation = validate_wal_chain(&wal_bytes, PAGE_SIZE, BIG_END_CKSUM)
        .expect("recovery chain should parse");
    assert_eq!(validation.first_invalid_frame, Some(30));
    assert_eq!(validation.valid_frames, first_invalid_frame);
    assert_eq!(validation.replayable_frames, first_invalid_frame);
    assert_eq!(
        validation.replayable_prefix_len,
        WAL_HEADER_SIZE + first_invalid_frame * FRAME_SIZE
    );
}

#[test]
fn test_wal_salt_mismatch_rejects() {
    let salts = WalSalts {
        salt1: 0xABCD_1234,
        salt2: 0x9876_5432,
    };
    let mut fixture = build_wal(&[1_u32; 8], salts);

    let mismatch_index = 3;
    let start = frame_offset(mismatch_index);
    let end = start + WAL_FRAME_HEADER_SIZE;
    write_wal_frame_salts(
        &mut fixture.frame_bytes[start..end],
        WalSalts {
            salt1: 0xDEAD_BEEF,
            salt2: 0xFACE_FEED,
        },
    )
    .expect("salt rewrite should succeed");

    let wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);
    let validation = validate_wal_chain(&wal_bytes, PAGE_SIZE, BIG_END_CKSUM)
        .expect("salt mismatch should parse");
    assert_eq!(validation.valid_frames, 3);
    assert_eq!(validation.first_invalid_frame, Some(3));
    assert_eq!(validation.reason, Some(WalChainInvalidReason::SaltMismatch));
}

#[test]
fn test_commit_frame_marker() {
    let salts = WalSalts {
        salt1: 0xABAB_CACA,
        salt2: 0xDADA_EFEF,
    };
    let fixture = build_wal(&[0_u32, 0, 8, 0, 0, 16, 0], salts);

    let wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);
    let validation =
        validate_wal_chain(&wal_bytes, PAGE_SIZE, BIG_END_CKSUM).expect("commit chain");
    assert_eq!(validation.valid_frames, 7);
    assert_eq!(validation.last_commit_frame, Some(5));
    assert_eq!(validation.replayable_frames, 6);
}

#[test]
fn test_partial_txn_discarded() {
    let salts = WalSalts {
        salt1: 0x0101_0202,
        salt2: 0x0303_0404,
    };
    let fixture = build_wal(&[0_u32, 0, 7, 0, 0], salts);

    let wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);
    let validation =
        validate_wal_chain(&wal_bytes, PAGE_SIZE, BIG_END_CKSUM).expect("partial chain");
    assert_eq!(validation.valid_frames, 5);
    assert_eq!(validation.last_commit_frame, Some(2));
    assert_eq!(validation.replayable_frames, 3);
}

#[test]
fn test_self_healing_random_access() {
    let salts = WalSalts {
        salt1: 0x1111_1111,
        salt2: 0x2222_2222,
    };
    let mut fixture = build_wal(&[1_u32, 1, 1, 1], salts);

    let damaged_frame_index = 1;
    let damaged_offset = frame_offset(damaged_frame_index) + WAL_FRAME_HEADER_SIZE + 77;
    fixture.frame_bytes[damaged_offset] ^= 0x80;

    let wal_bytes = wal_bytes(&fixture.wal_header, &fixture.frame_bytes);
    let chain_validation =
        validate_wal_chain(&wal_bytes, PAGE_SIZE, BIG_END_CKSUM).expect("damaged chain");
    assert_eq!(chain_validation.first_invalid_frame, Some(1));
    assert_eq!(
        chain_validation.reason,
        Some(WalChainInvalidReason::FrameChecksumMismatch)
    );

    let damaged_payload = frame_payload_slice(&fixture.frame_bytes, damaged_frame_index);
    let intact_payload = frame_payload_slice(&fixture.frame_bytes, 3);

    assert!(
        !verify_wal_fec_source_hash(damaged_payload, fixture.source_hashes[damaged_frame_index]),
        "bead_id={BEAD_3I98_ID} case=self_healing_detects_damaged_source"
    );
    assert!(
        verify_wal_fec_source_hash(intact_payload, fixture.source_hashes[3]),
        "bead_id={BEAD_3I98_ID} case=self_healing_validates_random_access_source"
    );
}

#[test]
fn test_e2e_bd_3i98() {
    let salts = WalSalts {
        salt1: 0x9090_A0A0,
        salt2: 0xB0B0_C0C0,
    };
    let fixture = build_wal(&[1_u32; 100], salts);

    for crash_frame in [0_usize, 1, 13, 37, 89] {
        let torn_cut = frame_offset(crash_frame) + WAL_FRAME_HEADER_SIZE + PAGE_SIZE / 3;
        let torn_frames = fixture.frame_bytes[..torn_cut].to_vec();
        let torn_wal_bytes = wal_bytes(&fixture.wal_header, &torn_frames);
        let torn_validation = validate_wal_chain(&torn_wal_bytes, PAGE_SIZE, BIG_END_CKSUM)
            .expect("torn WAL should parse");

        assert_eq!(torn_validation.valid_frames, crash_frame);
        assert_eq!(torn_validation.replayable_frames, crash_frame);
        assert_eq!(torn_validation.first_invalid_frame, Some(crash_frame));
    }

    let mut corrupted_frames = fixture.frame_bytes.clone();
    let corrupted_frame = 42;
    let corrupted_offset = frame_offset(corrupted_frame) + WAL_FRAME_HEADER_SIZE + 211;
    corrupted_frames[corrupted_offset] ^= 0x01;
    let corrupted_wal_bytes = wal_bytes(&fixture.wal_header, &corrupted_frames);
    let corrupted_validation =
        validate_wal_chain(&corrupted_wal_bytes, PAGE_SIZE, BIG_END_CKSUM).expect("corrupted WAL");

    assert_eq!(
        corrupted_validation.first_invalid_frame,
        Some(corrupted_frame)
    );
    assert_eq!(
        corrupted_validation.reason,
        Some(WalChainInvalidReason::FrameChecksumMismatch)
    );

    let mut checksummed_page = sample_payload(73);
    write_page_checksum(&mut checksummed_page).expect("page checksum write should succeed");
    assert!(verify_page_checksum(&checksummed_page).expect("checksum should verify"));
    checksummed_page[2048] ^= 0x04;
    assert!(
        !verify_page_checksum(&checksummed_page).expect("single-bit corruption should be detected")
    );
}

#[test]
fn test_e2e_bd_36hc() {
    let temp_dir = tempdir().expect("tempdir should be created");
    let db_path = temp_dir.path().join("e2e_bd_36hc.db");

    let mut setup_sql = String::from("PRAGMA page_size=4096;");
    for table_index in 0..50 {
        let _ = write!(
            setup_sql,
            "CREATE TABLE t{table_index}(id INTEGER PRIMARY KEY, v TEXT);"
        );
        let _ = write!(
            setup_sql,
            "CREATE INDEX i{table_index} ON t{table_index}(v);"
        );
        let _ = write!(
            setup_sql,
            "INSERT INTO t{table_index}(v) VALUES ('row-{table_index}');"
        );
    }

    let setup_output = sqlite3_exec(&db_path, &setup_sql);
    assert!(
        setup_output.status.success(),
        "sqlite3 setup failed: {}",
        String::from_utf8_lossy(&setup_output.stderr)
    );

    let pragma_output = sqlite3_exec(&db_path, "PRAGMA integrity_check;");
    assert!(
        pragma_output.status.success(),
        "sqlite3 integrity_check failed: {}",
        String::from_utf8_lossy(&pragma_output.stderr)
    );
    assert_eq!(String::from_utf8_lossy(&pragma_output.stdout).trim(), "ok");

    let level1 = integrity_check_level1_page(&sample_btree_leaf_page(), 1, true, false)
        .expect("level1 integrity check should run");
    let level2 = integrity_check_level2_btree(
        1,
        PAGE_SIZE,
        &[(128, 170), (220, 260), (300, 340)],
        &[10, 20, 30],
    );
    let level3 = integrity_check_level3_overflow_chain(1, &[4, 8, 12], 512);
    let level4 = integrity_check_level4_cross_reference(50, &(1..=50).collect::<Vec<u32>>());
    let level5 = integrity_check_level5_schema(&["CREATE TABLE x(id INTEGER)".to_owned()]);
    let report = merge_integrity_reports(&[level1, level2, level3, level4, level5]);
    assert!(report.is_ok());
    assert_eq!(report.sqlite_messages(), vec!["ok".to_owned()]);

    let salts = WalSalts {
        salt1: 0xABCD_1001,
        salt2: 0x1234_9001,
    };
    let fixture = build_wal(&[1_u32; 100], salts);
    for scenario in 0..100_usize {
        let crash_frame = (scenario * 19) % 100;
        let torn_cut = frame_offset(crash_frame) + WAL_FRAME_HEADER_SIZE + PAGE_SIZE / 3;
        let torn_frames = fixture.frame_bytes[..torn_cut].to_vec();
        let torn_wal_bytes = wal_bytes(&fixture.wal_header, &torn_frames);
        let validation = validate_wal_chain(&torn_wal_bytes, PAGE_SIZE, BIG_END_CKSUM)
            .expect("torn WAL should parse");
        assert_eq!(validation.valid_frames, crash_frame);
        assert_eq!(validation.replayable_frames, crash_frame);
        assert_eq!(validation.first_invalid_frame, Some(crash_frame));
    }
}