File size: 46,083 Bytes
9abc0a5
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.

"""TB2 environment server implementation (Spaces-compatible local mode)."""

from __future__ import annotations

import io
import logging
import os
import re
import shlex
import shutil
import tarfile
import threading
import sys
import urllib.request
import zipfile
from pathlib import Path
from typing import Any
from uuid import uuid4


if sys.version_info >= (3, 11):
    import tomllib
else:
    import tomli as tomllib

from openenv.core.env_server.interfaces import Environment


# Support both in-repo and standalone imports
try:
    # In-repo imports (when running from OpenEnv repository)
    from tbench2_env.models import Tbench2Action, Tbench2Observation, Tbench2State
except ImportError:
    # Standalone imports (when environment is standalone with openenv from pip)
    from models import Tbench2Action, Tbench2Observation, Tbench2State

_CAMEL_IMPORT_ERROR: Exception | None = None

# Official TB2 fixed paths: tests/test.sh assumes it runs from /tests and
# writes /logs/verifier/reward.txt. Module-level only so unit tests can
# redirect them off the real root filesystem.
_VERIFY_TESTS_DIR = "/tests"
_VERIFIER_LOG_DIR = "/logs/verifier"


def _hard_remove(path: str) -> None:
    """Remove whatever is at *path* β€” file, symlink, or directory tree.

    shutil.rmtree refuses to remove a symlink and, with ignore_errors=True,
    no-ops on one. That leaves an escape hatch: a root agent that symlinks a
    fixed path (/tests, /logs/verifier) at a directory it controls would keep
    that target alive across the "wipe", so a pre-planted conftest.py survives
    into scoring. Unlink the symlink itself before falling back to rmtree.
    """
    p = Path(path)
    if p.is_symlink() or p.is_file():
        p.unlink(missing_ok=True)
    else:
        shutil.rmtree(path, ignore_errors=True)


def _extractall(tar: tarfile.TarFile, dest: str) -> None:
    """extractall with the 3.12 data filter when available. The tarball is one
    this server wrote from a trusted tests/ dir, so the filter is defence in
    depth; on <3.12 (the ``filter`` kwarg predates it) fall back cleanly rather
    than raising TypeError mid-verify (the package targets Python >=3.10)."""
    try:
        tar.extractall(dest, filter="data")
    except TypeError:
        tar.extractall(dest)


def _require_terminal_toolkit() -> Any:
    global _CAMEL_IMPORT_ERROR
    if _CAMEL_IMPORT_ERROR is not None:
        raise RuntimeError(
            "camel-ai (TerminalToolkit) is required for TB2. Install from PyPI or from the CAMEL repo."
        ) from _CAMEL_IMPORT_ERROR

    try:
        from camel.toolkits import TerminalToolkit
    except Exception as exc:  # pragma: no cover
        _CAMEL_IMPORT_ERROR = exc
        raise RuntimeError(
            "camel-ai (TerminalToolkit) is required for TB2. Install from PyPI or from the CAMEL repo."
        ) from exc

    return TerminalToolkit


def _download_tb2_repo(cache_dir: Path) -> Path:
    repo_url = os.getenv(
        "TB2_REPO_URL",
        "https://github.com/laude-institute/terminal-bench-2/archive/refs/heads/main.zip",
    )
    cache_dir.mkdir(parents=True, exist_ok=True)
    archive_path = cache_dir / "terminal-bench-2.zip"

    if not archive_path.exists():
        urllib.request.urlretrieve(repo_url, archive_path)

    with zipfile.ZipFile(archive_path) as zf:
        root = zf.namelist()[0].split("/")[0]
        extract_dir = cache_dir / root
        if not extract_dir.exists():
            zf.extractall(cache_dir)

    return extract_dir


def _read_instruction(task_dir: Path) -> str:
    instruction_path = task_dir / "instruction.md"
    if instruction_path.exists():
        return instruction_path.read_text(encoding="utf-8")
    return ""


def _task_image_workdir(task_dir: Path) -> str:
    """WORKDIR pinned by the task's own image (environment/Dockerfile).

    Empty string when the task ships no Dockerfile or no WORKDIR; multi-stage
    Dockerfiles resolve to the last WORKDIR (the final stage's).
    """
    dockerfile = task_dir / "environment" / "Dockerfile"
    workdir = ""
    if dockerfile.is_file():
        for line in dockerfile.read_text(encoding="utf-8").splitlines():
            m = re.match(r"^\s*WORKDIR\s+(\S+)", line, re.IGNORECASE)
            if m:
                workdir = m.group(1)
    return workdir


def _workdir_is_server_tree(workdir: str) -> bool:
    """True when *workdir* contains this server's own code.

    A Dockerfile-parsed WORKDIR is only meaningful when the server runs
    inside the task image (per-task sandboxes, where the server layer lives
    elsewhere, e.g. /opt/envserver). The standard env-server image also
    installs to /app β€” the most common task WORKDIR β€” so the path merely
    existing is not enough: if the server's own code sits under it, it is
    the server tree, not the task tree.
    """
    try:
        return Path(__file__).resolve().is_relative_to(Path(workdir).resolve())
    except OSError:
        return True  # unresolvable path: fail toward the task-dir fallback


def _read_timeout(task_dir: Path, fallback: float) -> float:
    task_toml = task_dir / "task.toml"
    if not task_toml.exists():
        return fallback
    try:
        data = tomllib.loads(task_toml.read_text(encoding="utf-8"))
    except Exception:
        return fallback
    verifier = data.get("verifier", {})
    return float(verifier.get("timeout_sec", fallback))


# The scoring exec echoes its verdict on a marker line so the caller can parse
# it out of mixed stdout. Shared by both execution modes (local terminal
# toolkit and Docker container exec).
_REWARD_MARKER = "__TB2_REWARD__:"
_EXIT_CODE_MARKER = "__TB2_EXIT_CODE__:"


def _canonical_eval_cmd(workdir: str, timeout_s: float | None = None) -> str:
    """The official-harness scoring command, run from the agent's workdir.

    /tests/test.sh (staged by the caller) pins its own pytest toolchain (uvx:
    Python 3.13 + pytest 8.4.1 + ctrf), runs tests/test_outputs.py from
    _VERIFY_TESTS_DIR against the task workdir, and writes the binary result
    to /logs/verifier/reward.txt. test.sh stdout goes under _VERIFIER_LOG_DIR
    (wiped with the verify window) rather than a fixed /tmp path that would
    outlive scoring: its pytest -rA output can spell out expected values. Its
    tail is echoed back into the returned output β€” the episode is over by
    then, and callers need the pytest diagnostics on failure; the reward
    marker line stays last for parsing.

    ``timeout_s`` bounds test.sh with coreutils ``timeout`` when present in
    the image. The local mode passes None: its terminal toolkit enforces the
    budget itself. Docker exec has no server-side timeout, so the task's own
    verifier budget is enforced in-shell.
    """
    run = f"bash {_VERIFY_TESTS_DIR}/test.sh"
    if timeout_s is not None:
        run = f"if command -v timeout >/dev/null 2>&1; then timeout {int(timeout_s)} {run}; else {run}; fi"
    return (
        f"cd {shlex.quote(workdir)} && "
        f"{run} > {_VERIFIER_LOG_DIR}/testsh.log 2>&1; "
        f"tail -c 20000 {_VERIFIER_LOG_DIR}/testsh.log 2>/dev/null; "
        f"echo {_REWARD_MARKER}$(cat {_VERIFIER_LOG_DIR}/reward.txt 2>/dev/null)"
    )


def _parse_canonical_reward(output: str) -> float | None:
    """The verdict test.sh's verifier wrote to reward.txt, echoed on the
    marker line. None when no verdict can be recovered β€” no marker line, an
    empty value (reward.txt absent: test.sh crashed or was killed before its
    verifier wrote one), or a non-numeric value. A missing verdict is a
    scoring failure, not a task failure: callers raise so ``evaluate``
    reports an error (observation.error set, reward None) instead of a 0.0
    indistinguishable from tests genuinely failing β€” RL consumers must be
    able to drop such episodes rather than train on a false negative.
    """
    for line in output.splitlines()[::-1]:
        if _REWARD_MARKER in line:
            raw = line.split(_REWARD_MARKER, 1)[1].strip()
            if not raw:
                return None
            try:
                return float(raw)
            except ValueError:
                return None
    return None


def _require_canonical_verdict(reward: float | None, output: str) -> float:
    """Raise when the canonical harness produced no verdict (see above)."""
    if reward is None:
        raise RuntimeError(
            "canonical harness produced no verdict (reward.txt missing after "
            f"tests/test.sh ran); test.sh log tail: {output[-800:]!r}"
        )
    return reward


def _fallback_eval_cmd(workdir: str) -> str:
    """pytest against the staged tests copy, for task dirs without the
    canonical harness (none of the 89 official TB2 tasks β€” they all ship
    test.sh β€” but custom task dirs may only have bare pytest tests). Prefer
    uvx so pytest comes with its own toolchain like the canonical harness
    does. Verify from the same directory the agent worked in.
    """
    return (
        f"cd {shlex.quote(workdir)} && "
        "if command -v uvx >/dev/null 2>&1; "
        f"then uvx --with pytest==8.4.1 pytest -q {_VERIFY_TESTS_DIR} -rA; "
        f"else python -m pytest -q {_VERIFY_TESTS_DIR} -rA; fi; "
        f"echo {_EXIT_CODE_MARKER}$?"
    )


def _parse_exit_code_marker(output: str) -> int:
    for line in output.splitlines()[::-1]:
        if _EXIT_CODE_MARKER in line:
            try:
                return int(line.split(_EXIT_CODE_MARKER, 1)[1].strip())
            except Exception:
                return 1
    return 1


class Tbench2Environment(Environment[Tbench2Action, Tbench2Observation, Tbench2State]):
    """OpenEnv wrapper around Terminal-Bench 2 tasks (local execution)."""

    SUPPORTS_CONCURRENT_SESSIONS: bool = True

    def __init__(
        self,
        tasks_dir: str | None = None,
        output_dir: str | None = None,
        command_timeout_s: float | None = None,
        safe_mode: bool = False,
        default_task_id: str | None = None,
        withhold_tests: bool | None = None,
    ) -> None:
        super().__init__()
        self.tasks_dir = tasks_dir or os.getenv("TB2_TASKS_DIR", "")
        # RL hygiene: the env server and the agent share one container
        # filesystem, so tests/ and solution/ in the task dir are readable
        # (and writable) by the agent. When enabled, reset() moves them out
        # of reach β€” see _withhold_verifier_assets.
        if withhold_tests is None:
            withhold_tests = os.getenv("TB2_WITHHOLD_TESTS", "0") == "1"
        self.withhold_tests = withhold_tests
        self.output_dir = Path(
            output_dir or os.getenv("TB2_OUTPUT_DIR", "/tmp/tbench2_env_runs")
        )
        # Overridable via TB2_COMMAND_TIMEOUT_S: create_app instantiates the
        # environment with no arguments, and real TB2 agent commands / the
        # canonical tests/test.sh routinely exceed the old 20s default.
        if command_timeout_s is None:
            command_timeout_s = float(os.getenv("TB2_COMMAND_TIMEOUT_S", "20.0"))
        self.command_timeout_s = command_timeout_s
        self.safe_mode = safe_mode
        self.default_task_id = default_task_id or os.getenv(
            "TB2_DEFAULT_TASK_ID", "headless-terminal"
        )

        self._state = Tbench2State()
        self._task_dir: Path | None = None
        self._terminal_toolkit = None
        self._instruction = ""
        self._workdir = ""

    def reset(
        self,
        seed: int | None = None,
        episode_id: str | None = None,
        **kwargs: Any,
    ) -> Tbench2Observation:
        del seed

        TerminalToolkit = _require_terminal_toolkit()

        task_id = (
            kwargs.get("task_id") or kwargs.get("task_name") or self.default_task_id
        )
        task_path = kwargs.get("task_path") or kwargs.get("path")

        task_dir = self._resolve_task_path(task_id, task_path)
        resolved_task_id = task_id or task_dir.name

        self._instruction = _read_instruction(task_dir)
        self._task_dir = task_dir
        if self.withhold_tests:
            self._withhold_verifier_assets(task_dir)

        trial_name = f"{resolved_task_id}.{episode_id or uuid4().hex}"
        session_logs_dir = (
            self.output_dir / trial_name / "terminal_toolkit_session_logs"
        )
        session_logs_dir.mkdir(parents=True, exist_ok=True)

        # Commands run in the task image's real WORKDIR β€” where agents and
        # the canonical harness expect to operate, and not always /app
        # (fix-git: /app/personal-site, prove-plus-comm: /workspace).
        # TB2_TASK_WORKDIR overrides; otherwise the task's own Dockerfile is
        # parsed, trusted only when the path isn't the server's own install
        # tree (see _workdir_is_server_tree); plain local mode falls back to
        # the task source dir.
        workdir = os.getenv("TB2_TASK_WORKDIR", "").strip()
        if not workdir:
            workdir = _task_image_workdir(task_dir)
            if workdir and _workdir_is_server_tree(workdir):
                workdir = ""
        if not (workdir and Path(workdir).is_dir()):
            workdir = str(task_dir)
        self._workdir = workdir
        # No install_dependencies: evaluation runs the task's canonical
        # tests/test.sh, which pins its own pytest toolchain via uvx (see
        # _evaluate_canonical), so the toolkit venv does not need pytest.
        self._terminal_toolkit = TerminalToolkit(
            timeout=self.command_timeout_s,
            working_directory=workdir,
            use_docker_backend=False,
            session_logs_dir=session_logs_dir,
            safe_mode=self.safe_mode,
        )

        self._state = Tbench2State(
            episode_id=episode_id or str(uuid4()),
            step_count=0,
            task_id=resolved_task_id,
            task_path=str(task_dir),
            terminal_ready=True,
        )

        return Tbench2Observation(
            instruction=self._instruction,
            output="",
            success=True,
            error="",
            task_id=resolved_task_id,
            task_path=str(task_dir),
            session_id=None,
            action_type="reset",
            info={},
            reward=0.0,
            done=False,
        )

    def step(
        self,
        action: Tbench2Action,
        timeout_s: float | None = None,
        **kwargs: Any,
    ) -> Tbench2Observation:
        del timeout_s, kwargs

        if not isinstance(action, Tbench2Action):
            raise TypeError(f"Expected Tbench2Action, got {type(action)}")

        if self._terminal_toolkit is None or self._task_dir is None:
            raise RuntimeError("TB2 environment not initialized. Call reset() first.")

        self._state.step_count += 1
        self._state.last_action_type = action.action_type
        self._state.last_command = action.command

        output = ""
        error = ""
        success = True
        reward = None
        done = False
        info: dict[str, Any] = {}
        session_id = action.session_id or "tb2-session"

        try:
            if action.action_type == "exec":
                # Pass the timeout explicitly: camel's shell_exec has its own
                # per-call default (20s) and ignores the constructor timeout,
                # which silently truncates any longer-running agent command.
                output = self._terminal_toolkit.shell_exec(
                    command=action.command,
                    block=action.block,
                    id=session_id,
                    timeout=self.command_timeout_s,
                )
            elif action.action_type == "write":
                self._ensure_session_id(action.session_id, action.action_type)
                output = self._terminal_toolkit.shell_write_to_process(
                    id=action.session_id,
                    command=action.command,
                )
            elif action.action_type == "view":
                self._ensure_session_id(action.session_id, action.action_type)
                output = self._terminal_toolkit.shell_view(id=action.session_id)
            elif action.action_type == "wait":
                self._ensure_session_id(action.session_id, action.action_type)
                wait_seconds = action.wait_seconds or 0.0
                output = self._terminal_toolkit.shell_wait(
                    id=action.session_id,
                    wait_seconds=wait_seconds,
                )
            elif action.action_type == "kill":
                self._ensure_session_id(action.session_id, action.action_type)
                self._terminal_toolkit.shell_kill_process(id=action.session_id)
                output = f"Killed session {action.session_id}"
            elif action.action_type == "write_file":
                self._terminal_toolkit.shell_write_content_to_file(
                    content=action.content,
                    file_path=action.file_path,
                )
                output = f"Wrote content to {action.file_path}"
            elif action.action_type == "evaluate":
                output, reward, info = self._evaluate_task()
                done = True
            elif action.action_type == "close":
                self.close()
                output = "Closed TB2 environment."
                done = True
            else:
                raise ValueError(f"Unsupported action_type: {action.action_type}")
        except Exception as exc:  # pragma: no cover
            success = False
            error = str(exc)

        self._state.last_output = output
        self._state.session_id = session_id or ""

        return Tbench2Observation(
            instruction=self._instruction,
            output=output,
            success=success,
            error=error,
            task_id=self._state.task_id,
            task_path=self._state.task_path,
            session_id=session_id or "",
            action_type=action.action_type,
            info=info,
            reward=reward,
            done=done,
        )

    @property
    def state(self) -> Tbench2State:
        return self._state

    def close(self) -> None:
        self._terminal_toolkit = None
        self._task_dir = None
        self._instruction = ""

    def _resolve_task_path(self, task_id: str | None, task_path: str | None) -> Path:
        if task_path:
            resolved = Path(task_path).expanduser().resolve()
            if not resolved.exists():
                raise FileNotFoundError(f"Task path not found: {resolved}")
            return resolved

        if not task_id:
            raise ValueError("Provide task_id or task_path to reset TB2 environment.")

        if not self.tasks_dir:
            cache_dir = Path(
                os.getenv("TB2_CACHE_DIR", str(self.output_dir / "repo_cache"))
            )
            repo_dir = _download_tb2_repo(cache_dir)
            resolved = repo_dir / task_id
        else:
            resolved = Path(self.tasks_dir).expanduser().resolve() / task_id

        if not resolved.exists():
            raise FileNotFoundError(f"Task path not found: {resolved}")
        return resolved

    def _ensure_session_id(self, session_id: str | None, action_type: str) -> None:
        if not session_id:
            raise ValueError(f"session_id is required for action_type='{action_type}'")

    # tests/ tarballs withheld out of agent reach at reset(), keyed by task
    # dir. Class-level: the server may construct one environment instance per
    # session, and a later reset of the same task must still find the copy
    # after the on-disk source is gone. In-process only β€” withhold mode
    # therefore assumes a single server process owns the task filesystem for
    # its lifetime (the intended per-task-sandbox deployment: one uvicorn
    # worker, one ephemeral sandbox per episode). It is not safe with
    # ``uvicorn --workers N`` sharing one on-disk checkout, where a sibling
    # worker would see tests/ already deleted with no cache to restore from.
    _WITHHELD_TESTS: dict[str, bytes] = {}
    _WITHHOLD_LOCK = threading.Lock()

    def _withhold_verifier_assets(self, task_dir: Path) -> None:
        """Move verifier assets out of the agent's reach before it can act.

        The task directory is agent-readable (same filesystem, root agent):
        tests/test_outputs.py spells out the expected outputs and solution/ is
        the literal answer β€” for RL training both are reward-hacking bait.
        tests/ is read into server memory (the staging source for
        _stage_tests_for_verify) and removed from disk; solution/ is simply
        removed (nothing in this env reads it β€” it exists only for oracle
        runs). Gated behind TB2_WITHHOLD_TESTS=1 because in plain local mode
        task_dir may be a developer's working checkout, where deleting from
        it would be hostile.
        """
        key = str(task_dir)
        with self._WITHHOLD_LOCK:
            tests_dir = task_dir / "tests"
            if tests_dir.is_dir():
                if key not in self._WITHHELD_TESTS:
                    # realpath so a symlinked tests/ caches the target's files,
                    # not just a link member that would restore empty (tar.add
                    # does not follow a top-level symlink).
                    tests_real = os.path.realpath(tests_dir)
                    buf = io.BytesIO()
                    with tarfile.open(fileobj=buf, mode="w") as tar:
                        tar.add(tests_real, arcname=".")
                    self._WITHHELD_TESTS[key] = buf.getvalue()
            _hard_remove(str(tests_dir))
            _hard_remove(str(task_dir / "solution"))

    def _stage_tests_for_verify(self) -> bool:
        """Stage a pristine tests/ copy at the official fixed path for exactly
        the verify window. Caller must hold _CANONICAL_EVAL_LOCK.

        Both fixed paths are recreated from scratch (symlink included β€” see
        _hard_remove) so nothing an agent may have pre-planted survives into
        scoring: a /tests/conftest.py pytest would auto-load, or a symlinked
        /tests or /logs/verifier redirecting the stage at a dir the agent
        controls. When the source dir was withheld at reset, the staged copy
        comes from server memory: a copy the agent never had filesystem
        access to.
        """
        _hard_remove(_VERIFY_TESTS_DIR)
        _hard_remove(_VERIFIER_LOG_DIR)
        Path(_VERIFIER_LOG_DIR).mkdir(parents=True, exist_ok=True)

        blob = self._WITHHELD_TESTS.get(str(self._task_dir))
        if blob is not None:
            Path(_VERIFY_TESTS_DIR).mkdir(parents=True, exist_ok=True)
            with tarfile.open(fileobj=io.BytesIO(blob)) as tar:
                _extractall(tar, _VERIFY_TESTS_DIR)
            return True
        tests_dir = Path(self._task_dir) / "tests"
        if not tests_dir.is_dir():
            return False
        shutil.copytree(tests_dir, _VERIFY_TESTS_DIR, symlinks=True)
        return True

    def _evaluate_task(self) -> tuple[str, float, dict[str, Any]]:
        if self._task_dir is None:
            raise RuntimeError("TB2 environment not initialized. Call reset() first.")
        if self._terminal_toolkit is None:
            raise RuntimeError("Terminal toolkit not initialized.")

        # The task's own verifier budget (task.toml [verifier].timeout_sec) β€”
        # heavy tests legitimately run minutes (circuit-fibsqrt declares 3600s).
        verifier_timeout_s = _read_timeout(self._task_dir, fallback=900.0)

        with self._CANONICAL_EVAL_LOCK:
            try:
                # Staging happens inside the try: a stage that errors partway
                # (I/O failure mid-extract) must be wiped like a completed
                # one β€” step() reports scoring errors without ending the
                # episode, so the still-live session must not find a partial
                # tests/ copy left behind.
                if not self._stage_tests_for_verify():
                    return (
                        f"no tests/ found for task {self._state.task_id}",
                        0.0,
                        {"tests_passed": False, "error": "missing tests"},
                    )
                if (Path(_VERIFY_TESTS_DIR) / "test.sh").is_file():
                    return self._evaluate_canonical(verifier_timeout_s)
                return self._evaluate_fallback(verifier_timeout_s)
            finally:
                # Verifier artifacts live on disk only for the verify window:
                # don't leave them readable to a later episode / concurrent
                # session sharing this filesystem β€” or to the agent itself if
                # scoring times out / errors (done stays false, so it keeps
                # its session). /logs/verifier holds reward.txt and the
                # test.sh log, whose pytest -rA output can reveal expected
                # values.
                _hard_remove(_VERIFY_TESTS_DIR)
                _hard_remove(_VERIFIER_LOG_DIR)

    # The canonical harness uses the official fixed paths (/tests,
    # /logs/verifier/reward.txt), which are per-container, not per-session.
    # Serialize staging + evaluation so concurrent sessions on one server
    # cannot overwrite each other's staged tests or read another session's
    # reward.
    _CANONICAL_EVAL_LOCK = threading.Lock()

    def _evaluate_canonical(
        self, timeout_s: float
    ) -> tuple[str, float, dict[str, Any]]:
        """Score via the task's OFFICIAL harness, exactly as the TB2 verifier does.

        /tests/test.sh (staged by _stage_tests_for_verify) pins its own pytest
        toolchain (uvx: Python 3.13 + pytest 8.4.1 + ctrf), runs
        tests/test_outputs.py from /tests against the task workdir, and writes
        the binary result to /logs/verifier/reward.txt. Bare ``pytest tests/``
        (the fallback below) skips that toolchain pinning and mis-scores any
        task whose tests need it, so the canonical harness is preferred
        whenever the task ships it.
        """
        # Same working dir the agent operated in (resolved during reset).
        # The toolkit enforces the verifier budget itself, so the command
        # carries no in-shell timeout (see _canonical_eval_cmd).
        workdir = self._workdir or str(self._task_dir)
        output = self._terminal_toolkit.shell_exec(
            id="tb2-tests",
            command=_canonical_eval_cmd(workdir),
            block=True,
            timeout=timeout_s,
        )

        reward = _require_canonical_verdict(_parse_canonical_reward(output), output)
        info = {"tests_passed": reward == 1.0, "harness": "tests/test.sh"}
        return output, reward, info

    def _evaluate_fallback(self, timeout_s: float) -> tuple[str, float, dict[str, Any]]:
        """Scoring for task dirs without the canonical harness (see
        _fallback_eval_cmd)."""
        fallback_cwd = self._workdir or str(self._task_dir)
        output = self._terminal_toolkit.shell_exec(
            id="tb2-tests",
            command=_fallback_eval_cmd(fallback_cwd),
            block=True,
            timeout=timeout_s,
        )

        exit_code = _parse_exit_code_marker(output)
        reward = 1.0 if exit_code == 0 else 0.0
        info = {"tests_passed": exit_code == 0, "exit_code": exit_code}
        return output, reward, info


class Tbench2DockerEnvironment(
    Environment[Tbench2Action, Tbench2Observation, Tbench2State]
):
    """OpenEnv wrapper around Terminal-Bench 2 tasks with Docker isolation.

    This environment runs each task in its own Docker container built from
    the task's official image (task.toml's [environment] docker_image β€” tasks
    without one are rejected at reset; there is no host-execution fallback).
    Agent commands run in the image's own WORKDIR, and ``evaluate`` scores
    with the task's canonical tests/test.sh staged at the official fixed
    paths for exactly the verify window β€” the same scoring contract as the
    local mode, just delivered over container exec instead of the in-process
    terminal toolkit.

    Requires:
    - Docker socket mounted (/var/run/docker.sock)
    - Sufficient disk space for container images
    """

    SUPPORTS_CONCURRENT_SESSIONS: bool = True

    def __init__(
        self,
        tasks_dir: str | None = None,
        output_dir: str | None = None,
        command_timeout_s: float = 300.0,
        safe_mode: bool = True,
        default_task_id: str | None = None,
    ) -> None:
        super().__init__()
        self.tasks_dir = tasks_dir or os.getenv("TB2_TASKS_DIR", "")
        self.output_dir = Path(
            output_dir or os.getenv("TB2_OUTPUT_DIR", "/tmp/tbench2_env_runs")
        )
        self.command_timeout_s = command_timeout_s
        self.safe_mode = safe_mode
        self.default_task_id = default_task_id or os.getenv(
            "TB2_DEFAULT_TASK_ID", "headless-terminal"
        )

        self._state = Tbench2State()
        self._task_dir: Path | None = None
        self._docker_client = None
        self._container = None
        self._instruction = ""
        self._task_image = ""
        self._task_config: dict[str, Any] = {}
        self._workdir = ""

    def _get_docker_client(self) -> Any:
        """Lazy initialization of Docker client."""
        if self._docker_client is None:
            try:
                import docker

                self._docker_client = docker.from_env()
            except Exception as exc:
                raise RuntimeError(
                    f"Docker client not available. Ensure Docker socket is mounted. Error: {exc}"
                ) from exc
        return self._docker_client

    def reset(
        self,
        seed: int | None = None,
        episode_id: str | None = None,
        **kwargs: Any,
    ) -> Tbench2Observation:
        del seed

        task_id = (
            kwargs.get("task_id") or kwargs.get("task_name") or self.default_task_id
        )
        task_path = kwargs.get("task_path") or kwargs.get("path")

        task_dir = self._resolve_task_path(task_id, task_path)
        resolved_task_id = task_id or task_dir.name

        # Read task configuration including Docker image
        task_toml_path = task_dir / "task.toml"
        if task_toml_path.exists():
            task_config = tomllib.loads(task_toml_path.read_text(encoding="utf-8"))
            task_image = task_config.get("environment", {}).get("docker_image", "")
        else:
            task_image = ""
            task_config = {}

        instruction = _read_instruction(task_dir)

        # No host-execution fallback: silently running agent commands on the
        # env-server host would be a containment hole (arbitrary agent shell
        # outside any container) and a scoring-fidelity hole (no official
        # image, no canonical harness) at once. Every official TB2 task
        # declares its image; a task dir that doesn't is a bug to surface.
        if not task_image:
            # Fail closed: a rejected reset must not leave a previous
            # container usable with metadata from this new task.
            self.close()
            raise RuntimeError(
                f"task {resolved_task_id} declares no [environment] docker_image "
                "in task.toml; Docker mode runs every episode in the task's "
                "official container and does not fall back to executing on the "
                "server host. Fix the task, or use TB2_MODE=local."
            )

        # Create trial directory for logs
        trial_name = f"{resolved_task_id}.{episode_id or uuid4().hex}"
        trial_dir = self.output_dir / trial_name
        trial_dir.mkdir(parents=True, exist_ok=True)

        # A successful reset replaces the previous episode. Commit the new
        # metadata only after all task inputs have been validated, and leave
        # the session closed if container startup fails.
        self.close()
        self._task_config = task_config
        self._task_image = task_image
        self._instruction = instruction
        self._task_dir = task_dir
        try:
            self._start_container(task_dir, trial_dir)
        except Exception:
            self.close()
            raise

        return Tbench2Observation(
            instruction=self._instruction,
            output="",
            success=True,
            error="",
            task_id=resolved_task_id,
            task_path=str(task_dir),
            session_id=None,
            action_type="reset",
            info={"docker_image": self._task_image},
            reward=0.0,
            done=False,
        )

    def _start_container(self, task_dir: Path, trial_dir: Path) -> None:
        """Start a Docker container for the task.

        Uses file copying instead of bind mounts to support Docker-in-Docker
        scenarios where the server runs inside a container. Bind mounts reference
        host paths, which don't exist when the server is containerized.
        """
        docker = self._get_docker_client()

        try:
            # Pull image if needed
            try:
                image = docker.images.get(self._task_image)
            except Exception:
                logging.info(f"Pulling image {self._task_image}...")
                image = docker.images.pull(self._task_image)
                if isinstance(image, list):  # pull without a tag returns a list
                    image = image[0]

            self._workdir = self._resolve_workdir(image, task_dir)

            # Start container WITHOUT bind mounts (for DinD compatibility).
            # working_dir=/task only guarantees the task-source copy target
            # exists; every exec cd's into the resolved image WORKDIR.
            self._container = docker.containers.run(
                image=self._task_image,
                command="sleep infinity",
                detach=True,
                network_mode="host",
                working_dir="/task",
                remove=False,
            )

            # Copy task files into container using tar archive
            # This works in Docker-in-Docker because we read files from our
            # filesystem and stream them to the container via the Docker API.
            # Verifier assets stay out: the agent works in /task and must not
            # be able to read solution/ (the literal answer) or tests/ (the
            # expected outputs) β€” tests are staged only at verify time by
            # _evaluate_docker, like the official TB2 harness does.
            self._copy_dir_to_container(
                task_dir, "/task", exclude_top=("solution", "tests")
            )

            self._state = Tbench2State(
                episode_id=str(uuid4()),
                step_count=0,
                task_id=task_dir.name,
                task_path=str(task_dir),
                terminal_ready=True,
            )

        except Exception as exc:
            raise RuntimeError(f"Failed to start container: {exc}") from exc

    def _copy_dir_to_container(
        self, src_dir: Path, dest_path: str, exclude_top: tuple[str, ...] = ()
    ) -> None:
        """Copy a directory into the container using tar archive.

        This method streams files via the Docker API, avoiding bind mount
        issues in Docker-in-Docker scenarios. Top-level entries named in
        *exclude_top* are skipped entirely.
        """
        if self._container is None:
            raise RuntimeError("Container not started")

        # Create tar archive in memory (recursive=False: rglob already yields
        # every descendant, so per-entry recursion would duplicate members β€”
        # and would re-add excluded subtrees through their parents).
        tar_stream = io.BytesIO()
        with tarfile.open(fileobj=tar_stream, mode="w") as tar:
            for item in src_dir.rglob("*"):
                rel = item.relative_to(src_dir)
                if rel.parts and rel.parts[0] in exclude_top:
                    continue
                tar.add(str(item), arcname=str(rel), recursive=False)

        tar_stream.seek(0)

        # Copy to container
        self._container.put_archive(dest_path, tar_stream.getvalue())

    def _resolve_workdir(self, image: Any, task_dir: Path) -> str:
        """The dir agent commands and scoring run in: the task image's own
        WORKDIR β€” the real TB2 task state, not the /task source copy.

        Image metadata is authoritative (it sees a WORKDIR inherited from a
        base image, which Dockerfile parsing misses); fall back to parsing
        the task's Dockerfile, then to /task. The local mode's server-tree
        guard does not apply here: this server sits outside the container,
        so the image's /app is always the task tree.
        """
        try:
            workdir = (image.attrs.get("Config") or {}).get("WorkingDir") or ""
        except Exception:
            workdir = ""
        return workdir or _task_image_workdir(task_dir) or "/task"

    def _exec_in_container(
        self, command: str, workdir: str | None = None
    ) -> tuple[int, str]:
        """Execute a command inside the container, from the task workdir.

        The command rides as an argv element (bash -c <command>), not spliced
        into a quoted shell string β€” an agent command containing a single
        quote must arrive in the container byte-identical.
        """
        if self._container is None:
            raise RuntimeError("Container not started. Call reset() first.")

        cwd = workdir or self._workdir or "/task"
        exit_code, output = self._container.exec_run(
            cmd=["bash", "-c", f"cd {shlex.quote(cwd)} && {command}"],
            stdout=True,
            stderr=True,
        )
        return exit_code, output.decode("utf-8", errors="replace")

    def step(
        self,
        action: Tbench2Action,
        timeout_s: float | None = None,
        **kwargs: Any,
    ) -> Tbench2Observation:
        del timeout_s, kwargs

        if not isinstance(action, Tbench2Action):
            raise TypeError(f"Expected Tbench2Action, got {type(action)}")

        if self._task_dir is None:
            raise RuntimeError("TB2 environment not initialized. Call reset() first.")

        self._state.step_count += 1
        self._state.last_action_type = action.action_type
        self._state.last_command = action.command

        output = ""
        error = ""
        success = True
        reward = None
        done = False
        info: dict[str, Any] = {}
        session_id = action.session_id or "tb2-session"

        try:
            if action.action_type == "exec":
                exit_code, output = self._exec_in_container(action.command)
                success = exit_code == 0

            elif action.action_type == "write_file":
                exit_code, _ = self._exec_in_container(
                    f"cat > {action.file_path} << 'EOF'\n{action.content}\nEOF"
                )
                success = exit_code == 0
                output = f"Wrote to {action.file_path}"

            elif action.action_type == "evaluate":
                output, reward, info = self._evaluate_docker()
                done = True

            elif action.action_type == "close":
                self.close()
                output = "Closed TB2 environment."
                done = True

            else:
                raise ValueError(
                    f"Unsupported action_type in Docker mode: {action.action_type}"
                )

        except Exception as exc:
            success = False
            error = str(exc)

        self._state.last_output = output
        self._state.session_id = session_id or ""

        return Tbench2Observation(
            instruction=self._instruction,
            output=output,
            success=success,
            error=error,
            task_id=self._state.task_id,
            task_path=self._state.task_path,
            session_id=session_id or "",
            action_type=action.action_type,
            info=info,
            reward=reward,
            done=done,
        )

    def _evaluate_docker(self) -> tuple[str, float, dict[str, Any]]:
        """Score with the canonical harness inside the task container.

        Same scoring contract as the local mode's _evaluate_task: stage a
        pristine tests/ copy at the official fixed path for exactly the
        verify window, run the task's tests/test.sh from the dir the agent
        worked in (the image WORKDIR), read the binary verdict from
        /logs/verifier/reward.txt; task dirs without test.sh fall back to
        pytest. No cross-session lock is needed here, unlike local mode:
        every session drives its OWN container, so the fixed paths are
        session-private.
        """
        if self._container is None:
            raise RuntimeError("Container not started.")
        assert self._task_dir is not None, "Task directory not set"

        # Stage-at-verify, like the official TB2 harness: the initial /task
        # copy excludes tests/, and this server sits OUTSIDE the container, so
        # the copy staged here is one the agent never saw. rm -rf first so
        # nothing an agent pre-planted at the fixed paths survives into
        # scoring β€” a /tests/conftest.py pytest would auto-load, a symlink
        # redirecting the stage at a dir the agent controls, or a stale
        # /logs/verifier/reward.txt read back as a verdict.
        tests_src = self._task_dir / "tests"
        if not tests_src.is_dir():
            return (
                f"no tests/ found for task {self._state.task_id}",
                0.0,
                {"tests_passed": False, "error": "missing tests"},
            )

        # The task's own verifier budget (task.toml [verifier].timeout_sec) β€”
        # heavy tests legitimately run minutes (circuit-fibsqrt declares 3600s).
        verifier_timeout_s = _read_timeout(self._task_dir, fallback=900.0)
        workdir = self._workdir or "/task"

        wipe_ec, wipe_out = self._exec_in_container(
            f"rm -rf {_VERIFY_TESTS_DIR} {_VERIFIER_LOG_DIR} && "
            f"mkdir -p {_VERIFY_TESTS_DIR} {_VERIFIER_LOG_DIR}"
        )
        if wipe_ec != 0:
            # Fail closed: put_archive into a dir that survived the wipe would
            # merge the staged tests into whatever the agent planted there.
            raise RuntimeError(
                f"could not reset {_VERIFY_TESTS_DIR} before verify: {wipe_out.strip()}"
            )
        try:
            self._copy_dir_to_container(tests_src, _VERIFY_TESTS_DIR)

            if (tests_src / "test.sh").is_file():
                _, output = self._exec_in_container(
                    _canonical_eval_cmd(workdir, timeout_s=verifier_timeout_s)
                )
                reward = _require_canonical_verdict(
                    _parse_canonical_reward(output), output
                )
                info = {"tests_passed": reward == 1.0, "harness": "tests/test.sh"}
            else:
                _, output = self._exec_in_container(_fallback_eval_cmd(workdir))
                exit_code = _parse_exit_code_marker(output)
                reward = 1.0 if exit_code == 0 else 0.0
                info = {"tests_passed": exit_code == 0, "exit_code": exit_code}
        finally:
            # Verifier artifacts live in the container only for the verify
            # window, matching the local-mode staging: neither the staged
            # tests (expected values) nor /logs/verifier (reward + pytest -rA
            # log) may stay readable afterward β€” the agent keeps its session
            # if scoring errored (step() reports the failure without ending
            # the episode).
            try:
                rm_ec, rm_out = self._exec_in_container(
                    f"rm -rf {_VERIFY_TESTS_DIR} {_VERIFIER_LOG_DIR}"
                )
                if rm_ec != 0:
                    logging.warning(
                        "failed to remove staged %s after verify: %s",
                        _VERIFY_TESTS_DIR,
                        rm_out.strip(),
                    )
            except Exception:
                logging.warning(
                    "failed to remove staged %s after verify",
                    _VERIFY_TESTS_DIR,
                    exc_info=True,
                )

        return output, reward, info

    @property
    def state(self) -> Tbench2State:
        return self._state

    def close(self) -> None:
        if self._container:
            try:
                self._container.stop(timeout=10)
                self._container.remove(force=True)
            except Exception:
                pass
            self._container = None
        self._task_dir = None
        self._instruction = ""
        self._workdir = ""

    def _resolve_task_path(self, task_id: str | None, task_path: str | None) -> Path:
        if task_path:
            resolved = Path(task_path).expanduser().resolve()
            if not resolved.exists():
                raise FileNotFoundError(f"Task path not found: {resolved}")
            return resolved

        if not task_id:
            raise ValueError("Provide task_id or task_path to reset TB2 environment.")

        if not self.tasks_dir:
            cache_dir = Path(
                os.getenv("TB2_CACHE_DIR", str(self.output_dir / "repo_cache"))
            )
            repo_dir = _download_tb2_repo(cache_dir)
            resolved = repo_dir / task_id
        else:
            resolved = Path(self.tasks_dir).expanduser().resolve() / task_id

        if not resolved.exists():
            raise FileNotFoundError(f"Task path not found: {resolved}")
        return resolved