vivac 0.17.3

Provenance tree for work: every node knows which node it was born from
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
//! The two session hooks, against the binary.
//!
//! `f568`: Claude Code does have a `SessionEnd` event, but the automatic stop
//! hangs off `Stop` instead. `Stop` runs **on every turn**, so the automatic
//! stop has to know when there is nothing to stop for.

mod common;
use common::Sandbox;

fn how_many(vivacs: &str, kind: &str) -> usize {
    vivacs.lines().filter(|l| l.contains(kind)).count()
}

/// `Sandbox::run_stdin`, with `stdout` and `stderr` kept apart: proving the
/// copy warning does not repeat what the brief already showed needs the
/// two streams told apart, the same reason `tests/registry.rs`'s own
/// `run_split` exists.
fn run_stdin_split(c: &Sandbox, args: &[&str], stdin: &str) -> (String, String, i32) {
    use std::io::Write;
    let mut child = std::process::Command::new(env!("CARGO_BIN_EXE_vivac"))
        .current_dir(&c.0)
        .env("VIVAC_HOME", c.global_home())
        .env("TZ", "UTC")
        .args(args)
        .stdin(std::process::Stdio::piped())
        .stdout(std::process::Stdio::piped())
        .stderr(std::process::Stdio::piped())
        .spawn()
        .unwrap();
    child
        .stdin
        .take()
        .unwrap()
        .write_all(stdin.as_bytes())
        .unwrap();
    let o = child.wait_with_output().unwrap();
    (
        String::from_utf8_lossy(&o.stdout).into_owned(),
        String::from_utf8_lossy(&o.stderr).into_owned(),
        o.status.code().unwrap_or(-1),
    )
}

/// `t594`: `session start --hook` printed the brief --
/// which already opens with the copy block (`t594` §4.7) -- and then, once
/// its own write ran, the generic dispatch preamble said the very same
/// thing again on `stderr`. The two streams are checked apart, not
/// together: the review's own reproduction counted both at once, and that
/// is exactly what let the leak into `stderr` hide behind a passing count.
#[test]
fn session_start_hook_from_a_copy_shows_the_notice_once() {
    let original = Sandbox::new_seeded("session-copy-orig");
    original.ok(&["push", "a goal", "--why", "so the log has a first event"]);
    let copy = Sandbox::new_empty_in("session-copy-copy", original.global_home());
    std::fs::create_dir_all(copy.0.join(".vivac")).unwrap();
    std::fs::copy(
        original.0.join(".vivac").join("events"),
        copy.0.join(".vivac").join("events"),
    )
    .unwrap();

    let (stdout, stderr, code) = run_stdin_split(&copy, &["session", "start", "--hook"], "{}");
    assert_eq!(code, 0, "{stdout}{stderr}");
    assert_eq!(
        stdout.matches("COPY OF ANOTHER TREE").count(),
        1,
        "the brief itself must still carry it once:\n{stdout}"
    );
    assert_eq!(
        stderr.matches("COPY OF ANOTHER TREE").count(),
        0,
        "the stderr echo repeated what the brief already showed:\n{stderr}"
    );
}

/// Forty turns are not forty stops. A stop that repeats identically is not a
/// stop: it is a log.
#[test]
fn one_stop_per_turn_does_not_leave_one_stop_per_turn() {
    let c = Sandbox::new_seeded("turns");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    for _ in 0..5 {
        c.ok(&["session", "end", "--hook"]);
    }
    let v = c.ok(&["vivacs"]);
    assert_eq!(how_many(&v, "auto"), 1, "one stop per turn:\n{v}");
}

/// But as soon as the tree changes, the next stop does count.
#[test]
fn a_new_stop_once_something_changed() {
    let c = Sandbox::new_seeded("change");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.ok(&["session", "end", "--hook"]);
    c.ok(&["note", "1", "something happened"]);
    c.ok(&["session", "end", "--hook"]);
    let v = c.ok(&["vivacs"]);
    assert_eq!(how_many(&v, "auto"), 2, "it swallowed the good stop:\n{v}");
}

/// With no stack there is no pitch to close.
#[test]
fn no_stack_no_stop() {
    let c = Sandbox::new_seeded("nostack");
    c.ok(&["session", "end", "--hook"]);
    let v = c.ok(&["vivacs"]);
    assert_eq!(how_many(&v, "auto"), 0, "it invented an empty stop:\n{v}");
}

/// `f403`, `f404`: the brief goes straight to stdout in plain text, the shape
/// Claude Code's own hook reference says becomes context on `SessionStart`.
/// No JSON envelope, and the opening still lands in the log.
#[test]
fn the_start_hook_prints_the_brief_as_plain_text() {
    let c = Sandbox::new_seeded("plaintext");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    let (s, code) = c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"startup"}"#,
    );
    assert_eq!(code, 0, "{s}");
    assert!(!s.contains("hookSpecificOutput"), "{s}");
    assert!(s.starts_with("vivac · project:"), "{s}");
    assert!(s.contains("A goal"), "the brief went out empty:\n{s}");
    let log = c.log();
    assert!(log.contains("session.started"), "no opening:\n{log}");
    assert!(
        log.contains(r#""source":"startup""#),
        "the source did not survive:\n{log}"
    );
}

/// **A hook that fails in every directory without a tree gets switched off
/// within two days.** Both stay quiet and exit 0 where there is no `.vivac/`,
/// which is what makes it safe to leave them in the global configuration.
#[test]
fn they_stay_quiet_where_there_is_no_tree() {
    let c = Sandbox::new_empty("notree");
    for args in [["session", "start", "--hook"], ["session", "end", "--hook"]] {
        let (s, code) = c.run(&args);
        assert_eq!(code, 0, "{args:?} failed outside a tree:\n{s}");
        assert_eq!(s.trim(), "", "{args:?} said too much:\n{s}");
    }
}

/// `f708`: Codex's own hook manual is taxative about `Stop` -- plain text on
/// its stdout is **invalid**, and exiting 0 with nothing printed is what
/// counts as success there. The end hook already behaves this way, in every
/// shape a turn can leave it: no tree at all, a tree with nothing new to
/// close, and a tree with a change that does leave an automatic stop behind.
/// Nothing here made that true on purpose -- it only holds because nothing
/// in `session::end`'s hook path ever calls `outln!` -- so this is the test
/// that would have caught the day a courtesy line got added to it, the
/// mirror of [`the_start_hook_prints_the_brief_as_plain_text`] for the
/// opposite promise: not what the hook prints, but that it prints nothing
/// at all.
#[test]
fn the_end_hook_prints_nothing_to_stdout() {
    let no_tree = Sandbox::new_empty("end-hook-silent-no-tree");
    let (stdout, _stderr, code) = run_stdin_split(&no_tree, &["session", "end", "--hook"], "");
    assert_eq!(code, 0, "{stdout}");
    assert_eq!(
        stdout, "",
        "the end hook printed something with no tree:\n{stdout}"
    );

    let unchanged = Sandbox::new_seeded("end-hook-silent-unchanged");
    let (stdout, _stderr, code) = run_stdin_split(&unchanged, &["session", "end", "--hook"], "");
    assert_eq!(code, 0, "{stdout}");
    assert_eq!(
        stdout, "",
        "the end hook printed something with nothing changed:\n{stdout}"
    );

    let changed = Sandbox::new_seeded("end-hook-silent-changed");
    changed.ok(&["push", "A goal", "--why", "it is needed"]);
    let (stdout, _stderr, code) = run_stdin_split(&changed, &["session", "end", "--hook"], "");
    assert_eq!(code, 0, "{stdout}");
    assert_eq!(
        stdout, "",
        "the end hook printed something even though it left a stop:\n{stdout}"
    );
}

/// An automatic stop nobody declared still has to say something. Two autos in
/// a row that read identically do not segment a session, they log it (`f59`).
/// The label is derived from the seams --what the segment contained-- and never
/// from a judgement of relevance, which `DX` already measured at zero uses.
#[test]
fn an_automatic_stop_says_what_its_segment_contained() {
    let c = Sandbox::new_seeded("segment");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.ok(&["session", "end", "--hook"]);
    c.ok(&["add", "First finding", "--why", "it turned up"]);
    c.ok(&["add", "Second finding", "--why", "it turned up too"]);
    c.ok(&["session", "end", "--hook"]);
    let v = c.ok(&["vivacs"]);
    assert!(
        v.contains("2 new"),
        "the automatic stop did not say what it closed:\n{v}"
    );
}

/// Closing is as much of a seam as opening. A segment that only settled things
/// would otherwise read as if nothing had happened in it.
#[test]
fn an_automatic_stop_counts_what_its_segment_closed() {
    let c = Sandbox::new_seeded("closed");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.ok(&["add", "First finding", "--why", "it turned up"]);
    c.ok(&["session", "end", "--hook"]);
    c.ok(&["done", "2", "it was settled"]);
    c.ok(&["session", "end", "--hook"]);
    let v = c.ok(&["vivacs"]);
    assert!(
        v.contains("1 closed"),
        "the automatic stop counted no closes:\n{v}"
    );
}

/// A segment made only of notes is still a segment. The real tree has turns
/// that wrote nothing but notes, and they have to be tellable apart.
#[test]
fn an_automatic_stop_counts_the_notes_of_its_segment() {
    let c = Sandbox::new_seeded("notes");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.ok(&["session", "end", "--hook"]);
    c.ok(&["note", "1", "something turned up"]);
    c.ok(&["note", "1", "and something else"]);
    c.ok(&["session", "end", "--hook"]);
    let v = c.ok(&["vivacs"]);
    assert!(
        v.contains("2 notes"),
        "the automatic stop counted no notes:\n{v}"
    );
}

/// One note is a note, not notes. The label is prose the maintainer reads in
/// `vivac vivacs`, and prose that counts wrong reads like a machine talking.
#[test]
fn a_single_note_is_not_pluralised() {
    let c = Sandbox::new_seeded("plural");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.ok(&["session", "end", "--hook"]);
    c.ok(&["note", "1", "something turned up"]);
    c.ok(&["session", "end", "--hook"]);
    let v = c.ok(&["vivacs"]);
    assert!(v.contains("1 note"), "it counted no notes:\n{v}");
    assert!(!v.contains("1 notes"), "it said `1 notes`:\n{v}");
}

/// Not every seam is a birth, a close or a note. A segment that only raised a
/// flag still moved the tree, and if the label came out empty the stop would be
/// back to being the blank line `f59` was about.
#[test]
fn a_segment_of_none_of_the_three_still_says_something() {
    let c = Sandbox::new_seeded("other");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.ok(&["session", "end", "--hook"]);
    c.ok(&["flag", "1", "review", "--why", "it needs a second look"]);
    c.ok(&["session", "end", "--hook"]);
    let v = c.ok(&["vivacs"]);
    assert!(
        v.contains("1 change"),
        "the stop came out blank after a flag:\n{v}"
    );
}

/// `d45` retired the Spanish layer, and retiring it means the old spelling is
/// an unknown subcommand rather than a silent synonym. A word that is accepted
/// instead of rejected teaches the caller a spelling that does not exist, and
/// `session` was the last place in the product still doing it (`f57`).
#[test]
fn the_spanish_spellings_of_the_session_hooks_are_rejected() {
    let c = Sandbox::new_seeded("spanish");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    for args in [["session", "inicio"], ["session", "fin"]] {
        let (s, code) = c.run(&args);
        assert_ne!(code, 0, "`vivac {}` was accepted:\n{s}", args.join(" "));
        assert!(
            s.contains("usage"),
            "`vivac {}` failed without saying how:\n{s}",
            args.join(" ")
        );
    }
}

/// `SESSION-EVENT.md` §0: opening a session left no trace, so question 1 of
/// the falsification criterion --was the brief read?-- could not be answered
/// from the log at all. Only the gap between two writes, which also happens
/// when somebody goes to lunch.
#[test]
fn opening_a_session_leaves_a_trace() {
    let c = Sandbox::new_seeded("opening");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    let (out, code) = c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"startup"}"#,
    );
    assert_eq!(code, 0, "the start hook failed:\n{out}");
    assert!(
        c.log().contains("session.started"),
        "the opening left no trace:\n{}",
        c.log()
    );
}

/// The four openings are not the same experiment --the brief competes with
/// nothing on a cold start and with a whole restored transcript on a resume--
/// so which one it was has to survive into the log.
#[test]
fn the_source_of_the_opening_travels_into_the_log() {
    let c = Sandbox::new_seeded("source");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"compact"}"#,
    );
    assert!(
        c.log().contains(r#""source":"compact""#),
        "the source did not survive:\n{}",
        c.log()
    );
}

/// The hook writes; the command a person runs does not. `vivac session start`
/// typed by hand stays a pure read, which is what confines the write to the
/// seam of the machine.
#[test]
fn the_command_a_person_runs_writes_nothing() {
    let c = Sandbox::new_seeded("pureread");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    let before = c.log();
    c.ok(&["session", "start"]);
    assert_eq!(before, c.log(), "the read path wrote to the log");
}

/// A hook that fails in every directory gets switched off within two days,
/// and the measurement goes with it. Garbage on stdin is not a reason to fail.
#[test]
fn a_broken_payload_still_opens_the_session() {
    let c = Sandbox::new_seeded("garbage");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    let (out, code) = c.run_stdin(&["session", "start", "--hook"], "not json at all");
    assert_eq!(code, 0, "garbage on stdin took the hook down:\n{out}");
    assert!(
        c.log().contains(r#""source":"unknown""#),
        "an unsaid source has to read as `unknown`, not as empty:\n{}",
        c.log()
    );
}

/// An opening is a fact about the session, not about the tree. If it counted
/// as a change, the next `Stop` would leave an automatic stop for a session
/// that did nothing -- which is the repeated stop the guard exists to avoid.
#[test]
fn an_opening_does_not_arm_the_automatic_stop() {
    let c = Sandbox::new_seeded("noarm");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.ok(&["session", "end", "--hook"]);
    let before = how_many(&c.ok(&["vivacs"]), "auto");
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"startup"}"#,
    );
    c.ok(&["session", "end", "--hook"]);
    assert_eq!(
        how_many(&c.ok(&["vivacs"]), "auto"),
        before,
        "the opening armed a stop for a session that did nothing"
    );
}

/// What the brief claimed, so that "was it followed?" stops being a judgement
/// and becomes a query. The identifiers are the ones the rest of the log
/// already uses, not the alias, which is recomputed on every fold.
///
/// These are inputs, never a verdict: what counts as *following* the brief
/// lives in whoever reads.
#[test]
fn the_opening_records_what_the_brief_claimed() {
    let c = Sandbox::new_seeded("claimed");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"startup"}"#,
    );
    let log = c.log();
    let opening = log
        .lines()
        .find(|l| l.contains("session.started"))
        .unwrap_or_else(|| panic!("no opening in the log:\n{log}"));
    assert!(
        opening.contains(r#""session":"abc-123""#),
        "the session identifier did not survive:\n{opening}"
    );
    assert!(
        !opening.contains(r#""focus":null"#),
        "the opening recorded no focus, and there was one:\n{opening}"
    );
    // The push left a stop behind, so there is a last one to point at.
    assert!(
        !opening.contains(r#""vivac":null"#),
        "the opening recorded no last stop, and there was one:\n{opening}"
    );
}

/// The line inside the payload: an opaque identifier yes, a filesystem path
/// no. The transcript path arrives beside the session id and carries the
/// user's home directory, which the security pillar vetoes.
#[test]
fn the_transcript_path_never_reaches_the_log() {
    let c = Sandbox::new_seeded("noleak");
    c.ok(&["push", "A goal", "--why", "it is needed"]);
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"startup","transcript_path":"/home/someone/.claude/projects/x/y.jsonl","cwd":"/home/someone/work"}"#,
    );
    let log = c.log();
    assert!(
        !log.contains("someone"),
        "a path out of the payload reached the log:\n{log}"
    );
    assert!(
        !log.contains("transcript"),
        "the transcript path reached the log:\n{log}"
    );
}

/// With nothing on the stack the brief names no focus, and the opening has to
/// say so rather than invent one.
#[test]
fn an_opening_with_no_focus_records_none() {
    let c = Sandbox::new_seeded("nofocus");
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"startup"}"#,
    );
    let log = c.log();
    assert!(log.contains("session.started"), "no opening:\n{log}");
    assert!(
        log.contains(r#""focus":null"#),
        "it invented a focus out of an empty stack:\n{log}"
    );
}

/// A payload the guard refuses still opens the session: refusing the write
/// outright would drop the seam in silence, and a hook has nobody standing
/// by to reword the sentence that tripped it.
#[test]
fn a_refused_payload_still_opens_the_session() {
    let c = Sandbox::new_seeded("refused-open");
    let (out, code) = c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"/home/someone/.claude/projects/x"}"#,
    );
    assert_eq!(code, 0, "a refused field took the hook down:\n{out}");
    let log = c.log();
    assert!(log.contains("session.started"), "no opening:\n{log}");
    assert!(
        !log.contains("someone"),
        "the refused text reached the log:\n{log}"
    );
    assert!(
        log.contains(r#""source":"refused: "#),
        "the refused field was not replaced:\n{log}"
    );
}

/// What replaces a refused field names the rule and nothing past it, so the
/// log shows a refusal happened without repeating what caused it.
#[test]
fn the_refusal_names_the_rule_not_the_text() {
    let c = Sandbox::new_seeded("refused-rule");
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"abc-123","source":"/home/someone/.claude/projects/x"}"#,
    );
    let log = c.log();
    assert!(
        log.contains(r#""source":"refused: path to a user home directory (personal data)""#),
        "the rule did not land in the field as written:\n{log}"
    );
}

/// A refused session identifier is no different from a refused source: it
/// does not take the rest of the opening, or its sibling field, down with it.
#[test]
fn a_refused_session_identifier_does_not_take_the_opening_down() {
    let c = Sandbox::new_seeded("refused-session");
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"someone@example.com","source":"startup"}"#,
    );
    let log = c.log();
    assert!(log.contains("session.started"), "no opening:\n{log}");
    assert!(
        log.contains(r#""source":"startup""#),
        "the clean field was touched by its refused sibling:\n{log}"
    );
    assert!(
        !log.contains("someone@example.com"),
        "the refused session identifier reached the log:\n{log}"
    );
    assert!(
        log.contains(r#""session":"refused: email address (personal data)""#),
        "the session field was not replaced:\n{log}"
    );
}

/// The regression that matters most: a real, UUID-shaped session identifier
/// from Claude Code passes through untouched. This rests on `known_shape`
/// exempting UUIDs from the entropy check.
#[test]
fn a_real_session_identifier_passes_through_untouched() {
    let c = Sandbox::new_seeded("real-session");
    c.run_stdin(
        &["session", "start", "--hook"],
        r#"{"session_id":"019316f8-4c2a-7b31-9f0e-8d1a2b3c4d5e","source":"startup"}"#,
    );
    let log = c.log();
    assert!(
        log.contains("019316f8-4c2a-7b31-9f0e-8d1a2b3c4d5e"),
        "a real session identifier did not survive:\n{log}"
    );
    assert!(
        !log.contains("refused:"),
        "the guard fired on a real payload:\n{log}"
    );
}

// ---------------------------------------------------------------------------
// `d738`: the hook brief names the capture seams. `f737` measured why -- an
// agent with no project doctrine of its own only writes to the tree when a
// person asks, because nothing it receives unasked says when to.
// ---------------------------------------------------------------------------

/// The approved text, byte for byte (`d757`). Widths measured by machine,
/// every line included, none over the 76-column ceiling that
/// `capture_seams_lines_never_widen_past_76_columns`, below, checks against
/// the real rendering rather than against this constant.
const CAPTURE_SEAMS_BLOCK: &str = "\n WRITE AT THESE SEAMS\n  Look first: vivac find \"<words>\". Work the tree already holds goes under\n  its node, never into a second one. The focus above is where work was\n  left, maybe not by you: hang new work from what it continues.\n  Write before you answer: what you tell the person goes in the tree first.\n  new line of work     vivac push \"<title>\" --why \"<why>\" --parent <id>\n                       or --root, when it continues nothing in the tree\n  a choice is settled  vivac decide \"<t>\" --reason \"<r>\" --alternative \"<x>\"\n  you report findings  vivac add \"<t>\" --type finding --why \"<where>\"\n                       as you tell the person, one for each thing found\n                       asks nothing? close it: vivac done <id> \"Record: ...\"\n  told \"not now\"       vivac park <id> \"<their words>\"\n                       nothing to park yet? vivac add it, then park it\n  changed outside git  vivac note <id> \"<what changed, where>\"\n                       CI, a tracker, the cloud: the tree is its only record\n  the work is done     vivac pop \"<outcome>\"\n                       and again if that settles the node it returns to\n  Or the same moves through the vivac_* tools.\n";

/// Test (a): the hook's own brief carries the block, exactly.
#[test]
fn the_hook_brief_names_the_capture_seams() {
    let c = Sandbox::new_seeded("capture-seams-hook");
    let (s, code) = c.run_stdin(&["session", "start", "--hook"], "{}");
    assert_eq!(code, 0, "{s}");
    assert!(
        s.contains(CAPTURE_SEAMS_BLOCK),
        "the hook brief did not carry the capture-seams block byte for byte:\n{s}"
    );
    // It sits right ahead of the closing rule and the tokens/depth footer,
    // not buried earlier in the body.
    let block_at = s.find(CAPTURE_SEAMS_BLOCK).unwrap();
    let footer_at = s.find("tokens · depth").unwrap();
    assert!(
        block_at < footer_at,
        "the block did not land ahead of the footer:\n{s}"
    );
}

/// Test (b)'s other half lives in `tests/brief.rs`, as
/// `the_capture_seams_block_is_hook_only`; this is the same claim read off
/// the person-facing render this file already exercises: a plain `vivac
/// session start` (no `--hook`) is the CLI path a person runs, and it stays
/// out.
#[test]
fn a_person_running_session_start_without_hook_gets_no_capture_seams() {
    let c = Sandbox::new_seeded("capture-seams-no-hook");
    let out = c.ok(&["session", "start"]);
    assert!(
        !out.contains("WRITE AT THESE SEAMS"),
        "a person reading `vivac session start` was told when to write:\n{out}"
    );
}

/// Test (f): no line of the block, as actually rendered, is wider than 76
/// columns. Read off `s` itself rather than off [`CAPTURE_SEAMS_BLOCK`], so
/// a row that grows without anyone updating that constant still gets
/// caught here.
#[test]
fn capture_seams_lines_never_widen_past_76_columns() {
    let c = Sandbox::new_seeded("capture-seams-width");
    let (s, code) = c.run_stdin(&["session", "start", "--hook"], "{}");
    assert_eq!(code, 0, "{s}");
    let start = s
        .find(" WRITE AT THESE SEAMS")
        .expect("no capture-seams heading in the hook brief");
    let block = &s[start..];
    let end = block.find("\n\n").unwrap_or(block.len());
    for line in block[..end].lines() {
        assert!(
            line.chars().count() <= 76,
            "a capture-seams line is wider than 76 columns ({} chars): {line:?}",
            line.chars().count()
        );
    }
}

/// A command line, split the way a shell would: whitespace-separated,
/// except inside a pair of double quotes. Enough to run the exact commands
/// the capture-seams block shows, placeholders swapped for real values.
fn shell_split(line: &str) -> Vec<String> {
    let mut args = Vec::new();
    let mut current = String::new();
    let mut in_quotes = false;
    for c in line.chars() {
        match c {
            '"' => in_quotes = !in_quotes,
            c if c.is_whitespace() && !in_quotes => {
                if !current.is_empty() {
                    args.push(std::mem::take(&mut current));
                }
            }
            c => current.push(c),
        }
    }
    if !current.is_empty() {
        args.push(current);
    }
    args
}

/// Test (d): every command the block shows is a real one -- its verb
/// dispatches, and every flag on its row is a flag that verb accepts.
/// Checked two ways per row: a bogus flag on the verb comes back with
/// "does not take" (the verb was recognised) rather than "unknown command"
/// (it was not), and the row itself, with its `<placeholders>` swapped for
/// real values, exits 0.
///
/// `d757` adds the look-first line's own `vivac find` and `push`'s new
/// `--parent <id>`: `push` needs a real, open node to point `--parent` at,
/// the same as `park` and `pop` already need one to act on, so it joins
/// them below.
#[test]
fn every_capture_seam_command_dispatches_and_takes_its_flags() {
    let rows = [
        "vivac find \"<words>\"",
        "vivac push \"<title>\" --why \"<why>\" --parent <id>",
        "vivac decide \"<t>\" --reason \"<r>\" --alternative \"<x>\"",
        "vivac add \"<t>\" --type finding --why \"<where>\"",
        "vivac done <id> \"Record: ...\"",
        "vivac park <id> \"<their words>\"",
        "vivac note <id> \"<what changed, where>\"",
        "vivac pop \"<outcome>\"",
    ];
    for row in rows {
        let mut argv = shell_split(row);
        assert_eq!(argv.remove(0), "vivac");
        let verb = argv[0].clone();

        // The verb dispatches: a bogus flag is refused by name, not by
        // "unknown command" -- proof the command itself was recognised.
        let (out, code) = Sandbox::new_seeded(&format!("capture-seams-bogus-{verb}"))
            .run(&[verb.as_str(), "--bogus-flag-for-this-test"]);
        assert_ne!(code, 0, "a bogus flag was silently accepted:\n{out}");
        assert!(
            out.contains("does not take"),
            "{verb} did not dispatch as a known command:\n{out}"
        );
        assert!(
            !out.contains(&format!("unknown command: {verb}")),
            "{verb} is not a real command:\n{out}"
        );

        // Every flag on the row is accepted: the row itself, run for real
        // with placeholders swapped for plain values, exits 0.
        let c = Sandbox::new_seeded(&format!("capture-seams-real-{verb}"));
        if verb == "park" || verb == "pop" || verb == "push" || verb == "done" || verb == "note" {
            c.ok(&["push", "a title to act on", "--why", "seed"]);
        }
        let real_args: Vec<String> = argv
            .into_iter()
            .map(|a| {
                if a == "<id>" {
                    "1".to_string()
                } else if a.starts_with('<') && a.ends_with('>') {
                    "a value".to_string()
                } else {
                    a
                }
            })
            .collect();
        let arg_refs: Vec<&str> = real_args.iter().map(String::as_str).collect();
        c.ok(&arg_refs);
    }

    // `--root` is `push`'s own other way of saying where a node is born
    // (`d757`'s hint line names it): on an empty stack it needs nothing to
    // point at and still exits 0.
    let c = Sandbox::new_seeded("capture-seams-push-root");
    c.ok(&["push", "A goal", "--why", "a value", "--root"]);
}

// ---------------------------------------------------------------------------
// `d779`: `session prompt --hook`. Read-only against the tree, and always
// exits 0: the seams tell an agent when to write, and this is the one that
// fires when nothing did, on every message rather than at the two
// boundaries of a session.
//
// `d787`: what counts as "quiet" is minutes the agent spent working, not
// wall-clock minutes since the last write -- the stretch a person takes to
// answer no longer counts against it (`f786`). `prompt` opens a turn on
// every call and `session end --hook` (the `Stop` hook) closes it, folding
// the turn's length into a per-session accumulator kept outside the log;
// `prompt` resets that accumulator the moment it sees a newer capture.
// ---------------------------------------------------------------------------

/// The exact two-line text, `{n}` filled in with the whole minutes of work
/// accumulated since the last thing worth calling a reference point -- the
/// session's own opening, or a capture since, whichever is more recent.
fn nudge_text(n: i64) -> String {
    format!(
        "vivac: nothing written to the tree in {n} min of work in this session. If a seam\npassed since (a new line of work, a choice, a finding you told, a \"not now\", work done, a change outside the repo), write it now, before you answer.\n"
    )
}

/// A raw `session.started` line, appended straight to `events` so its `ts`
/// can be set by hand: the CLI itself only ever stamps the real clock, and
/// this test needs a session that has been open for an exact, arbitrary
/// stretch.
fn raw_session_started(seq: u64, ts: &str, lane: &str) -> String {
    format!(
        r#"{{"seq":{seq},"id":"01PROMPTSTARTEDAAAAAAAAA{seq:02}","ts":"{ts}","actor":"a_test0000000","lane":"{lane}","payload":{{"type":"session.started","source":"test"}}}}"#
    )
}

/// A raw capture event -- `node.noted`, chosen because it is on the list and
/// needs no real node to name -- at a `ts` this test controls.
fn raw_capture(seq: u64, ts: &str, lane: &str) -> String {
    format!(
        r#"{{"seq":{seq},"id":"01PROMPTCAPTUREAAAAAAAA{seq:02}","ts":"{ts}","actor":"a_test0000000","lane":"{lane}","payload":{{"type":"node.noted","node":"ghost","note":"synthetic capture"}}}}"#
    )
}

/// A raw `vivac.created` of kind `auto` -- the automatic stop the `Stop`
/// hook writes on an ordinary turn, never a capture in its own right.
fn raw_auto_vivac(seq: u64, ts: &str, lane: &str) -> String {
    format!(
        r#"{{"seq":{seq},"id":"01PROMPTAUTOAAAAAAAAAAAA{seq:02}","ts":"{ts}","actor":"a_test0000000","lane":"{lane}","payload":{{"type":"vivac.created","vivac":"01PROMPTAUTOVIVACAAAAAAA{seq:02}","num":{seq},"kind":"auto","stack":[],"working_set":[],"next_intent":""}}}}"#
    )
}

/// `session prompt --hook`, with a minimal stdin payload and an explicit
/// `--now`, the way `brief`'s own tests pin the clock.
fn run_prompt(c: &Sandbox, now: &str) -> (String, i32) {
    c.run_stdin(
        &["session", "prompt", "--hook", "--now", now],
        r#"{"session_id":"s1"}"#,
    )
}

/// `session end --hook` (the `Stop` hook), with the same session payload
/// `run_prompt` uses so the two resolve to the same turn/cooldown key, and
/// the same explicit `--now`.
fn run_stop(c: &Sandbox, now: &str) -> (String, i32) {
    c.run_stdin(
        &["session", "end", "--hook", "--now", now],
        r#"{"session_id":"s1"}"#,
    )
}

/// The FNV-1a 64-bit hash `cooldown_path` (`session.rs`) names the turn
/// state file with, copied rather than exposed: this crate publishes only a
/// binary, so the tests have nothing to link against and reach for a copy
/// the same way `tests/setup.rs` already does for the same algorithm.
fn fnv1a64(data: &[u8]) -> u64 {
    let mut hash: u64 = 0xcbf29ce484222325;
    for &b in data {
        hash ^= u64::from(b);
        hash = hash.wrapping_mul(0x100000001b3);
    }
    hash
}

/// Where `session.rs`'s own `cooldown_path` writes this sandbox's turn
/// state, for the one test that needs to damage it by hand. Mirrors
/// `state_key` exactly: the project's first event id (read off the log's
/// own first line, the same field `first_event_id` reads), the lane, and
/// the session id, hashed the same way.
fn prompt_state_path(c: &Sandbox, lane: &str, session: &str) -> std::path::PathBuf {
    let log = c.log();
    let first_line = log.lines().next().expect("no first event to key by");
    let v: serde_json::Value = serde_json::from_str(first_line).unwrap();
    let project_id = v["id"].as_str().unwrap();
    let key = format!("{project_id}\u{0}{lane}\u{0}{session}");
    let hash = fnv1a64(key.as_bytes());
    std::env::temp_dir()
        .join("vivac")
        .join(format!("prompt-{hash:016x}"))
}

#[test]
fn with_no_session_started_it_says_nothing() {
    let c = Sandbox::new_seeded("prompt-no-session-start");
    let (out, code) = run_prompt(&c, "2026-09-24T09:20:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "");
}

/// `d787`: with no turn ever closed by a `Stop`, nothing has accumulated,
/// no matter how much wall clock passed since the session opened. This
/// replaces `a_three_minute_old_session_says_nothing`, which tested the
/// wall-clock floor `PROMPT_SESSION_MIN` used to enforce -- dropped along
/// with the constant, since active time already implies it.
#[test]
fn with_no_turn_closed_yet_it_says_nothing_no_matter_how_long() {
    let c = Sandbox::new_seeded("prompt-no-turn-yet");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    let (out, code) = run_prompt(&c, "2026-09-24T12:00:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "");
}

/// `d787`'s central case: a prompt opens a turn, the `Stop` hook closes it
/// eleven minutes later, and the next prompt speaks off that eleven minutes
/// of work -- replacing `a_twenty_minute_session_with_no_capture_says_twenty`
/// and `a_capture_four_minutes_ago_in_a_twenty_minute_session_says_nothing`,
/// which both measured wall clock from the session's own opening rather
/// than a turn a `Stop` actually closed.
#[test]
fn a_turn_that_worked_past_ten_minutes_speaks_at_the_next_prompt() {
    let c = Sandbox::new_seeded("prompt-turn-eleven");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    let (out, code) = run_prompt(&c, "2026-09-24T09:00:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "");
    let (out, code) = run_stop(&c, "2026-09-24T09:11:00Z");
    assert_eq!(code, 0, "{out}");
    let (out, code) = run_prompt(&c, "2026-09-24T09:30:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, nudge_text(11));
}

/// `f786`'s own regression: the agent wrote at minute one, the person took
/// thirty-nine minutes to answer, and none of that wait is work. Before
/// `d787` this read as thirty-nine idle minutes and spoke; now the turn the
/// `Stop` closed was one minute long, and the wait after it is wall clock,
/// not work, so the next prompt stays quiet.
#[test]
fn a_long_wait_after_a_short_turn_says_nothing() {
    let c = Sandbox::new_seeded("prompt-f786-wait");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    let (out, code) = run_prompt(&c, "2026-09-24T09:00:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "");
    let (out, code) = run_stop(&c, "2026-09-24T09:01:00Z");
    assert_eq!(code, 0, "{out}");
    let (out, code) = run_prompt(&c, "2026-09-24T09:40:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "", "a wait between turns was counted as work:\n{out}");
}

/// Work accumulates across turns rather than resetting with each one: three
/// turns of four minutes each, none alone past `PROMPT_QUIET_MIN`, add up to
/// twelve and the prompt right after the third speaks.
#[test]
fn three_four_minute_turns_add_up_to_twelve() {
    let c = Sandbox::new_seeded("prompt-turns-add-up");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));

    run_prompt(&c, "2026-09-24T09:00:00Z");
    run_stop(&c, "2026-09-24T09:04:00Z");
    let (out, code) = run_prompt(&c, "2026-09-24T09:04:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "", "spoke after only four minutes of work:\n{out}");

    run_stop(&c, "2026-09-24T09:08:00Z");
    let (out, code) = run_prompt(&c, "2026-09-24T09:08:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "", "spoke after only eight minutes of work:\n{out}");

    run_stop(&c, "2026-09-24T09:12:00Z");
    let (out, code) = run_prompt(&c, "2026-09-24T09:12:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(
        out,
        nudge_text(12),
        "three four-minute turns did not add up to twelve:\n{out}"
    );
}

/// A capture landing after work has accumulated takes the count back to
/// zero: the reference point moved, so what came before it stops counting.
/// Replaces `a_capture_twelve_minutes_ago_in_a_thirty_minute_session_says_twelve`,
/// which measured wall clock from a raw capture rather than from work a
/// `Stop` had actually closed.
#[test]
fn a_capture_after_twelve_minutes_clears_the_active_minutes() {
    let c = Sandbox::new_seeded("prompt-capture-clears");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    run_prompt(&c, "2026-09-24T09:00:00Z");
    run_stop(&c, "2026-09-24T09:12:00Z");
    // Twelve minutes of work are on the books; a capture lands after them.
    c.append_raw_line(&raw_capture(101, "2026-09-24T09:13:00Z", "main"));
    let (out, code) = run_prompt(&c, "2026-09-24T09:20:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(
        out, "",
        "the capture did not clear the active minutes:\n{out}"
    );
}

/// An automatic stop from the `Stop` hook is not a capture: reading it as
/// one would let a turn that only ever closed itself with `auto` clear the
/// accumulated minutes it should be adding to.
#[test]
fn an_automatic_stop_in_the_log_does_not_clear_the_active_minutes() {
    let c = Sandbox::new_seeded("prompt-auto-not-capture");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    run_prompt(&c, "2026-09-24T09:00:00Z");
    run_stop(&c, "2026-09-24T09:11:00Z");
    c.append_raw_line(&raw_auto_vivac(101, "2026-09-24T09:11:30Z", "main"));
    let (out, code) = run_prompt(&c, "2026-09-24T09:20:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(
        out,
        nudge_text(11),
        "an automatic stop cleared the active minutes:\n{out}"
    );
}

/// Having spoken once, the same session stays quiet for ten minutes even
/// though the accumulator keeps climbing underneath the silence; past the
/// cooldown, with enough work still on the books, it speaks again.
#[test]
fn cooldown_still_holds_then_speaks_again_once_it_clears() {
    let c = Sandbox::new_seeded("prompt-cooldown-active");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));

    run_prompt(&c, "2026-09-24T09:00:00Z");
    run_stop(&c, "2026-09-24T09:11:00Z");
    let (first, code) = run_prompt(&c, "2026-09-24T09:11:00Z");
    assert_eq!(code, 0, "{first}");
    assert_eq!(first, nudge_text(11));

    run_stop(&c, "2026-09-24T09:12:00Z");
    let (second, code) = run_prompt(&c, "2026-09-24T09:12:00Z");
    assert_eq!(code, 0, "{second}");
    assert_eq!(second, "", "spoke again inside the cooldown:\n{second}");

    run_stop(&c, "2026-09-24T09:22:00Z");
    let (third, code) = run_prompt(&c, "2026-09-24T09:22:00Z");
    assert_eq!(code, 0, "{third}");
    assert_eq!(
        third,
        nudge_text(22),
        "stayed quiet past the cooldown:\n{third}"
    );
}

/// A state file from before `d787`, holding a bare last-nudge integer, or
/// simply damaged, reads back as all zeros -- the same "never seen this
/// session" as a missing file -- rather than taking the hook down.
#[test]
fn a_broken_state_file_reads_back_as_zero_and_does_not_crash() {
    let c = Sandbox::new_seeded("prompt-broken-state");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    run_prompt(&c, "2026-09-24T09:00:00Z");
    run_stop(&c, "2026-09-24T09:11:00Z");
    let path = prompt_state_path(&c, "main", "s1");

    for broken in ["not a state file at all", "1758700800"] {
        std::fs::write(&path, broken).unwrap();
        let (out, code) = run_prompt(&c, "2026-09-24T09:30:00Z");
        assert_eq!(code, 0, "{out}");
        assert_eq!(
            out, "",
            "a broken state file ({broken:?}) did not read back as zeros:\n{out}"
        );
    }
}

/// Garbage on stdin only costs the turn/cooldown key its session id: the
/// rest of the computation still runs off the log and the state file, so a
/// turn opened and closed under the very same garbage still adds up to a
/// real nudge, not an outright failure.
#[test]
fn broken_stdin_still_exits_zero_and_the_nudge_still_works() {
    let c = Sandbox::new_seeded("prompt-broken-stdin");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    let (out, code) = c.run_stdin(
        &[
            "session",
            "prompt",
            "--hook",
            "--now",
            "2026-09-24T09:00:00Z",
        ],
        "not json at all",
    );
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "");
    let (out, code) = c.run_stdin(
        &["session", "end", "--hook", "--now", "2026-09-24T09:11:00Z"],
        "not json at all",
    );
    assert_eq!(code, 0, "{out}");
    let (out, code) = c.run_stdin(
        &[
            "session",
            "prompt",
            "--hook",
            "--now",
            "2026-09-24T09:30:00Z",
        ],
        "not json at all",
    );
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, nudge_text(11));
}

/// The same promise with no payload at all rather than a malformed one.
#[test]
fn empty_stdin_still_exits_zero_and_the_nudge_still_works() {
    let c = Sandbox::new_seeded("prompt-empty-stdin");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    let (out, code) = c.run_stdin(
        &[
            "session",
            "prompt",
            "--hook",
            "--now",
            "2026-09-24T09:00:00Z",
        ],
        "",
    );
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "");
    let (out, code) = c.run_stdin(
        &["session", "end", "--hook", "--now", "2026-09-24T09:11:00Z"],
        "",
    );
    assert_eq!(code, 0, "{out}");
    let (out, code) = c.run_stdin(
        &[
            "session",
            "prompt",
            "--hook",
            "--now",
            "2026-09-24T09:30:00Z",
        ],
        "",
    );
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, nudge_text(11));
}

#[test]
fn outside_a_tree_it_exits_zero_and_says_nothing() {
    let c = Sandbox::new_empty("prompt-no-tree");
    let (out, code) = run_prompt(&c, "2026-09-24T09:20:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, "");
}

/// Every hook reads the whole payload the harness writes, even where there
/// is no tree and nothing to do. A payload larger than a pipe's buffer
/// makes this deterministic: a hook that exits without reading leaves the
/// write blocked until it dies and then failing with a broken pipe, which
/// is what a harness would get.
#[test]
fn every_hook_drains_its_input_even_outside_a_tree() {
    use std::io::Write;
    let c = Sandbox::new_empty("hooks-drain-stdin");
    let payload = format!(
        "{{\"session_id\":\"s1\",\"source\":\"startup\",\"pad\":\"{}\"}}",
        "x".repeat(256 * 1024)
    );
    for sub in ["start", "prompt", "end"] {
        let mut child = std::process::Command::new(env!("CARGO_BIN_EXE_vivac"))
            .current_dir(&c.0)
            .args(["session", sub, "--hook"])
            .stdin(std::process::Stdio::piped())
            .stdout(std::process::Stdio::piped())
            .stderr(std::process::Stdio::piped())
            .spawn()
            .unwrap();
        let wrote = child.stdin.take().unwrap().write_all(payload.as_bytes());
        let o = child.wait_with_output().unwrap();
        assert!(
            wrote.is_ok(),
            "session {sub} --hook left its input unread: {wrote:?}"
        );
        assert_eq!(o.status.code(), Some(0), "session {sub} --hook");
    }
}

/// The one promise that matters most: whatever it decides to say, the hook
/// never writes a byte to the log itself -- its own bookkeeping lives in
/// the state file `prompt_state_path` names, never in `.vivac/events`.
#[test]
fn the_log_never_grows_from_calling_it() {
    let c = Sandbox::new_seeded("prompt-log-unchanged");
    c.append_raw_line(&raw_session_started(100, "2026-09-24T09:00:00Z", "main"));
    run_prompt(&c, "2026-09-24T09:00:00Z");
    run_stop(&c, "2026-09-24T09:11:00Z");
    let before = c.log();
    let (out, code) = run_prompt(&c, "2026-09-24T09:30:00Z");
    assert_eq!(code, 0, "{out}");
    assert_eq!(out, nudge_text(11), "the fixture stopped nudging");
    assert_eq!(before, c.log(), "session prompt wrote to the log");
}