diff --git a/src/borg/testsuite/archives_test.py b/src/borg/testsuite/archives_test.py
new file mode 100644
index 0000000000..de8045d92d
--- /dev/null
+++ b/src/borg/testsuite/archives_test.py
@@ -0,0 +1,611 @@
+from argparse import Namespace
+from datetime import datetime, timezone
+from unittest.mock import Mock, patch
+
+import pytest
+
+from borgstore.store import ItemInfo, ObjectNotFound as StoreObjectNotFound
+
+from ..helpers.errors import CommandError, Error
+from ..helpers.parseformat import bin_to_hex
+from ..helpers.time import parse_timestamp
+from ..manifest import Archives, ArchiveInfo, ArchivesInterface
+from ..repository import Repository
+
+
+def _id(n):
+    return bytes([n]) * 32
+
+
+TS = "2020-06-01T12:00:00.000000"
+TS2 = "2021-06-01T12:00:00.000000"
+
+
+def _item(id_bytes):
+    return ItemInfo(name=bin_to_hex(id_bytes), exists=True, size=0, directory=False)
+
+
+def _make():
+    repo = Mock()
+    repo.store_list.return_value = []
+    manifest = Mock()
+    return Archives(repo, manifest), repo, manifest
+
+
+def _archive_meta(name, id_, ts=TS, *, username="", hostname="", tags=()):
+    return {
+        "id": id_,
+        "name": name,
+        "time": ts,
+        "exists": True,
+        "username": username,
+        "hostname": hostname,
+        "size": 0,
+        "nfiles": 0,
+        "comment": "",
+        "tags": tags,
+    }
+
+
+def _info(name, id_, ts=TS, *, username="", hostname="", tags=()):
+    return ArchiveInfo(name=name, id=id_, ts=parse_timestamp(ts), tags=tags, user=username, host=hostname)
+
+
+def _stub_matching_info_tuples(infos):
+    ar, _, _ = _make()
+    ar._matching_info_tuples = Mock(side_effect=lambda match_patterns, match_end, deleted=False: list(infos))
+    return ar
+
+
+def _stub_info_tuples(infos):
+    ar, _, _ = _make()
+    ar._info_tuples = Mock(side_effect=lambda deleted=False: iter(infos))
+    return ar
+
+
+def test_archives_satisfies_archives_interface():
+    ar, _, _ = _make()
+    assert isinstance(ar, ArchivesInterface)
+
+
+def test_prepare_is_noop():
+    ar, repo, manifest = _make()
+    m = Mock()
+    ar.prepare(manifest, m)
+    repo.assert_not_called()
+    manifest.assert_not_called()
+    m.assert_not_called()
+
+
+def test_finish_returns_empty_dict():
+    ar, _, manifest = _make()
+    assert ar.finish(manifest) == {}
+
+
+def test_ids_empty():
+    ar, _, _ = _make()
+    assert list(ar.ids()) == []
+
+
+def test_ids_returns_binary_ids():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1)), _item(_id(2))]
+    assert list(ar.ids()) == [_id(1), _id(2)]
+
+
+def test_ids_store_object_not_found_gives_empty():
+    ar, repo, _ = _make()
+    repo.store_list.side_effect = StoreObjectNotFound("archives")
+    assert list(ar.ids()) == []
+
+
+def test_ids_passes_deleted_flag():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1))]
+    result = list(ar.ids(deleted=True))
+    assert result == [_id(1)]
+    repo.store_list.assert_called_once_with("archives", deleted=True)
+
+
+def test_count_empty():
+    ar, _, _ = _make()
+    assert ar.count() == 0
+
+
+def test_count():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1)), _item(_id(2))]
+    assert ar.count() == 2
+
+
+def test_names():
+    ar, _, _ = _make()
+    metas = [_archive_meta("a", _id(1)), _archive_meta("b", _id(2))]
+    ar._infos = Mock(side_effect=lambda deleted=False: iter(metas))
+    assert list(ar.names()) == ["a", "b"]
+
+
+def test_exists_true():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([_archive_meta("a", _id(1))]))
+    assert ar.exists("a") is True
+
+
+def test_exists_false():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([]))
+    assert ar.exists("missing") is False
+
+
+def test_exists_id_true():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1))]
+    assert ar.exists_id(_id(1)) is True
+
+
+def test_exists_id_false():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = []
+    assert ar.exists_id(_id(99)) is False
+
+
+def test_exists_id_deleted():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1))]
+    assert ar.exists_id(_id(1), deleted=True) is True
+    repo.store_list.assert_called_with("archives", deleted=True)
+
+
+def test_exists_name_and_id_true():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([_archive_meta("a", _id(1))]))
+    assert ar.exists_name_and_id("a", _id(1)) is True
+
+
+def test_exists_name_and_id_false_wrong_name():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([_archive_meta("a", _id(1))]))
+    assert ar.exists_name_and_id("b", _id(1)) is False
+
+
+def test_exists_name_and_id_false_wrong_id():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([_archive_meta("a", _id(1))]))
+    assert ar.exists_name_and_id("a", _id(2)) is False
+
+
+def test_exists_name_and_ts_true():
+    ar, _, _ = _make()
+    ar._info_tuples = Mock(side_effect=lambda deleted=False: iter([_info("a", _id(1))]))
+    assert ar.exists_name_and_ts("a", parse_timestamp(TS)) is True
+
+
+def test_exists_name_and_ts_false_wrong_ts():
+    ar, _, _ = _make()
+    ar._info_tuples = Mock(side_effect=lambda deleted=False: iter([_info("a", _id(1))]))
+    assert ar.exists_name_and_ts("a", parse_timestamp(TS2)) is False
+
+
+def test_exists_name_and_ts_false_wrong_name():
+    ar, _, _ = _make()
+    ar._info_tuples = Mock(side_effect=lambda deleted=False: iter([_info("a", _id(1))]))
+    assert ar.exists_name_and_ts("b", parse_timestamp(TS)) is False
+
+
+def test_get_archive_meta_object_not_found():
+    ar, repo, _ = _make()
+    repo.get.side_effect = Repository.ObjectNotFound(_id(1), "/fake/path")
+    result = ar._get_archive_meta(_id(1))
+    assert result == {
+        "id": _id(1),
+        "name": "archive-does-not-exist",
+        "time": "1970-01-01T00:00:00.000000",
+        "exists": False,
+        "username": "",
+        "hostname": "",
+        "tags": (),
+    }
+
+
+def test_get_archive_meta_success():
+    ar, _, manifest = _make()
+    manifest.repo_objs.parse.return_value = (None, b"data")
+    manifest.key.unpack_archive.return_value = {
+        "version": 2,
+        "name": "myarchive",
+        "time": "2021-03-15T10:00:00.000000",
+        "username": "alice",
+        "hostname": "myhost",
+        "size": 1024,
+        "nfiles": 3,
+        "comment": "weekly",
+    }
+
+    result = ar._get_archive_meta(_id(1))
+
+    assert result["exists"] is True
+    assert result["id"] == _id(1)
+    assert result["name"] == "myarchive"
+    assert result["time"] == "2021-03-15T10:00:00.000000"
+    assert result["username"] == "alice"
+    assert result["hostname"] == "myhost"
+    assert result["size"] == 1024
+    assert result["nfiles"] == 3
+    assert result["comment"] == "weekly"
+    assert result["tags"] == ()
+
+
+def test_get_archive_meta_success_with_tags():
+    ar, _, manifest = _make()
+    manifest.repo_objs.parse.return_value = (None, b"data")
+    manifest.key.unpack_archive.return_value = {
+        "version": 2,
+        "name": "tagged",
+        "time": TS,
+        "username": "",
+        "hostname": "",
+        "tags": ["beta", "alpha"],
+    }
+
+    result = ar._get_archive_meta(_id(1))
+
+    assert result["tags"] == ("alpha", "beta")
+    assert result["size"] == 0
+    assert result["nfiles"] == 0
+    assert result["comment"] == ""
+
+
+def test_get_archive_meta_bad_version():
+    ar, _, manifest = _make()
+    manifest.repo_objs.parse.return_value = (None, b"data")
+    manifest.key.unpack_archive.return_value = {"version": 99}
+
+    with pytest.raises(Exception, match="Unknown archive metadata version"):
+        ar._get_archive_meta(_id(1))
+
+
+def test_get_missing_returns_none():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([]))
+    assert ar.get("nope") is None
+
+
+def test_get_returns_archive_info():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([_archive_meta("a", _id(1))]))
+    info = ar.get("a")
+    assert isinstance(info, ArchiveInfo)
+    assert info.name == "a"
+    assert info.id == _id(1)
+
+
+def test_get_raw():
+    ar, _, _ = _make()
+    ar._infos = Mock(side_effect=lambda deleted=False: iter([_archive_meta("a", _id(1))]))
+    result = ar.get("a", raw=True)
+    assert result["name"] == "a"
+    assert result["id"] == _id(1)
+    assert result["time"] == TS
+    assert result["exists"] is True
+
+
+def test_get_by_id_missing_returns_none():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = []
+    assert ar.get_by_id(_id(99)) is None
+
+
+@pytest.mark.parametrize("raw", [False, True])
+def test_get_by_id(raw):
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1))]
+    ar._get_archive_meta = Mock(side_effect=lambda id_: _archive_meta("a", _id(1)))
+    result = ar.get_by_id(_id(1), raw=raw)
+    if raw:
+        assert result["name"] == "a"
+        assert result["id"] == _id(1)
+        assert result["time"] == TS
+        assert result["exists"] is True
+    else:
+        assert isinstance(result, ArchiveInfo)
+        assert result.name == "a"
+        assert result.id == _id(1)
+
+
+def test_get_by_id_exists_false_returns_none():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1))]
+    meta = _archive_meta("a", _id(1))
+    meta["exists"] = False
+    ar._get_archive_meta = Mock(side_effect=lambda id_: meta)
+    assert ar.get_by_id(_id(1)) is None
+
+
+def test_get_by_id_deleted():
+    ar, repo, _ = _make()
+    repo.store_list.return_value = [_item(_id(1))]
+    ar._get_archive_meta = Mock(side_effect=lambda id_: _archive_meta("a", _id(1)))
+    info = ar.get_by_id(_id(1), deleted=True)
+    assert isinstance(info, ArchiveInfo)
+    repo.store_list.assert_called_with("archives", deleted=True)
+
+
+def test_create_calls_store_store():
+    ar, repo, _ = _make()
+    ar.create("a", _id(1), TS)
+    repo.store_store.assert_called_once_with(f"archives/{bin_to_hex(_id(1))}", b"")
+
+
+def test_create_with_datetime_ts():
+    ar, repo, _ = _make()
+    dt = datetime(2020, 6, 1, 12, 0, 0, tzinfo=timezone.utc)
+    ar.create("a", _id(1), dt)
+    repo.store_store.assert_called_once_with(f"archives/{bin_to_hex(_id(1))}", b"")
+
+
+def test_create_overwrite_kwarg_ignored():
+    # borgstore store_store is ID-addressed and idempotent; overwrite is an ArchivesInterface
+    # compatibility parameter that Archives intentionally ignores (unlike LegacyArchives).
+    ar, repo, _ = _make()
+    ar.create("a", _id(1), TS, overwrite=True)
+    repo.store_store.assert_called_once_with(f"archives/{bin_to_hex(_id(1))}", b"")
+
+
+def test_delete_by_id():
+    ar, repo, _ = _make()
+    ar.delete_by_id(_id(1))
+    repo.store_move.assert_called_once_with(f"archives/{bin_to_hex(_id(1))}", delete=True)
+
+
+def test_undelete_by_id():
+    ar, repo, _ = _make()
+    ar.undelete_by_id(_id(1))
+    repo.store_move.assert_called_once_with(f"archives/{bin_to_hex(_id(1))}", undelete=True)
+
+
+def test_nuke_by_id():
+    ar, repo, _ = _make()
+    ar.nuke_by_id(_id(1))
+    repo.store_delete.assert_called_once_with(f"archives/{bin_to_hex(_id(1))}", deleted=True)
+
+
+def test_list_no_filters():
+    info = _info("a", _id(1))
+    ar = _stub_matching_info_tuples([info])
+    assert ar.list() == [info]
+
+
+def test_list_sort_by_str_raises():
+    ar, _, _ = _make()
+    with pytest.raises(TypeError, match="sort_by must be a sequence"):
+        ar.list(sort_by="name")
+
+
+def test_list_sort_generator_not_materialised_regression():
+    # _matching_info_tuples must materialise _info_tuples() via list() before returning;
+    # if that list() call is removed, the raw generator reaches .sort() and raises AttributeError.
+    ar = _stub_info_tuples([])
+    assert ar.list(sort_by=["name"]) == []
+
+
+def test_list_sort_by():
+    i1 = _info("b", _id(2), TS2)
+    i2 = _info("a", _id(1), TS)
+    ar = _stub_matching_info_tuples([i1, i2])
+    result = ar.list(sort_by=["name"])
+    assert result == [i2, i1]
+
+
+def test_list_reverse():
+    i1 = _info("a", _id(1))
+    i2 = _info("b", _id(2))
+    ar = _stub_matching_info_tuples([i1, i2])
+    assert ar.list(reverse=True) == [i2, i1]
+
+
+def test_list_first():
+    infos = [_info(f"a{i}", _id(i + 1)) for i in range(5)]
+    ar = _stub_matching_info_tuples(infos)
+    assert ar.list(first=3) == infos[:3]
+
+
+def test_list_last():
+    infos = [_info(f"a{i}", _id(i + 1)) for i in range(5)]
+    ar = _stub_matching_info_tuples(infos)
+    assert ar.list(last=2) == infos[-2:]
+
+
+def test_list_first_zero():
+    infos = [_info(f"a{i}", _id(i + 1)) for i in range(3)]
+    ar = _stub_matching_info_tuples(infos)
+    assert ar.list(first=0) == infos
+
+
+def test_list_last_zero():
+    infos = [_info(f"a{i}", _id(i + 1)) for i in range(3)]
+    ar = _stub_matching_info_tuples(infos)
+    assert ar.list(last=0) == infos
+
+
+def test_list_date_filter():
+    i1 = _info("a", _id(1))
+    ar = _stub_matching_info_tuples([i1])
+    with patch("borg.manifest.filter_archives_by_date", return_value=[i1]) as mock_filter:
+        result = ar.list(older="1d")
+    assert result == [i1]
+    mock_filter.assert_called_once_with([i1], oldest=None, newest=None, newer=None, older="1d")
+
+
+def test_list_deleted_passes_flag():
+    ar, _, _ = _make()
+    ar._info_tuples = Mock(side_effect=lambda deleted=False: iter([]))
+    ar.list(deleted=True)
+    ar._info_tuples.assert_called_once_with(deleted=True)
+
+
+def test_list_match_name():
+    i1 = _info("archive-a", _id(1))
+    i2 = _info("archive-b", _id(2))
+    ar = _stub_info_tuples([i1, i2])
+    assert ar.list(match=["archive-a"]) == [i1]
+
+
+def test_list_match_name_prefix():
+    i1 = _info("archive-a", _id(1))
+    i2 = _info("other", _id(2))
+    ar = _stub_info_tuples([i1, i2])
+    assert ar.list(match=["name:archive-a"]) == [i1]
+
+
+def test_list_match_user():
+    i1 = _info("a", _id(1), username="alice")
+    i2 = _info("b", _id(2), username="bob")
+    ar = _stub_info_tuples([i1, i2])
+    assert ar.list(match=["user:alice"]) == [i1]
+
+
+def test_list_match_host():
+    i1 = _info("a", _id(1), hostname="laptop")
+    i2 = _info("b", _id(2), hostname="server")
+    ar = _stub_info_tuples([i1, i2])
+    assert ar.list(match=["host:laptop"]) == [i1]
+
+
+def test_list_match_tags():
+    i1 = _info("a", _id(1), tags=("prod", "db"))
+    i2 = _info("b", _id(2), tags=("dev",))
+    ar = _stub_info_tuples([i1, i2])
+    assert ar.list(match=["tags:prod"]) == [i1]
+
+
+def test_list_match_aid():
+    i1 = _info("a", _id(1))
+    ar = _stub_info_tuples([i1])
+    prefix = bin_to_hex(_id(1))[:4]
+    assert ar.list(match=[f"aid:{prefix}"]) == [i1]
+
+
+def test_list_match_aid_ambiguous():
+    # Two distinct IDs that share the same leading byte — a realistic prefix collision.
+    id1 = bytes([0x01, 0x00]) + bytes(30)
+    id2 = bytes([0x01, 0x01]) + bytes(30)
+    i1 = _info("a", id1)
+    i2 = _info("b", id2)
+    ar = _stub_info_tuples([i1, i2])
+    prefix = bin_to_hex(id1)[:2]  # "01" — matches both IDs
+    with pytest.raises(CommandError, match=r"precisely one"):
+        ar.list(match=[f"aid:{prefix}"])
+
+
+def test_list_match_multiple_patterns():
+    i1 = _info("archive-a", _id(1), username="alice", hostname="laptop")
+    i2 = _info("archive-b", _id(2), username="alice", hostname="server")
+    i3 = _info("archive-c", _id(3), username="bob", hostname="laptop")
+    ar = _stub_info_tuples([i1, i2, i3])
+    result = ar.list(match=["user:alice", "host:laptop"])
+    assert result == [i1]
+
+
+def test_list_match_end_custom():
+    i1 = _info("archive-a", _id(1))
+    i2 = _info("other", _id(2))
+    ar = _stub_info_tuples([i1, i2])
+    result = ar.list(match=["archive"], match_end="")
+    assert result == [i1]
+
+
+def test_get_one_exact_match():
+    i1 = _info("backup", _id(1))
+    ar = _stub_info_tuples([i1])
+    assert ar.get_one(["backup"]) == i1
+
+
+def test_get_one_no_match_raises():
+    ar = _stub_info_tuples([])
+    with pytest.raises(CommandError, match=r"matched 0\."):
+        ar.get_one(["missing"])
+
+
+def test_get_one_multiple_matches_raises():
+    i1 = _info("a", _id(1))
+    i2 = _info("a", _id(2))
+    ar = _stub_info_tuples([i1, i2])
+    with pytest.raises(CommandError, match=r"matched 2\."):
+        ar.get_one(["a"])
+
+
+def test_get_one_deleted_passes_flag():
+    i1 = _info("a", _id(1))
+    ar, _, _ = _make()
+    ar._info_tuples = Mock(side_effect=lambda deleted=False: iter([i1]))
+    ar.get_one(["a"], deleted=True)
+    ar._info_tuples.assert_called_once_with(deleted=True)
+
+
+def test_list_considering_raises_if_name_set():
+    ar, _, _ = _make()
+    args = Mock()
+    args.name = "archive"
+    with pytest.raises(Error):
+        ar.list_considering(args)
+
+
+def test_list_considering_delegates():
+    i1 = _info("b", _id(2), TS2)
+    i2 = _info("a", _id(1), TS)
+    ar = _stub_matching_info_tuples([i1, i2])
+    args = Namespace(
+        name=None,
+        sort_by="name",
+        match_archives=None,
+        first=None,
+        last=None,
+        older=None,
+        newer=None,
+        oldest=None,
+        newest=None,
+        deleted=False,
+    )
+    result = ar.list_considering(args)
+    assert result == [i2, i1]
+
+
+def test_list_considering_with_match_archives():
+    i1 = _info("archive-a", _id(1))
+    i2 = _info("other", _id(2))
+    ar = _stub_info_tuples([i1, i2])
+    args = Namespace(
+        name=None,
+        sort_by="name",
+        match_archives=["archive-a"],
+        first=None,
+        last=None,
+        older=None,
+        newer=None,
+        oldest=None,
+        newest=None,
+        deleted=False,
+    )
+    result = ar.list_considering(args)
+    assert result == [i1]
+
+
+def test_list_considering_multi_key_sort():
+    i1 = _info("b", _id(1), TS2)
+    i2 = _info("a", _id(2), TS2)
+    i3 = _info("c", _id(3), TS)
+    ar = _stub_matching_info_tuples([i1, i2, i3])
+    args = Namespace(
+        name=None,
+        sort_by="ts,name",
+        match_archives=None,
+        first=None,
+        last=None,
+        older=None,
+        newer=None,
+        oldest=None,
+        newest=None,
+        deleted=False,
+    )
+    result = ar.list_considering(args)
+    assert result == [i3, i2, i1]
diff --git a/src/borg/testsuite/legacy_archives_test.py b/src/borg/testsuite/legacy_archives_test.py
new file mode 100644
index 0000000000..c17be15740
--- /dev/null
+++ b/src/borg/testsuite/legacy_archives_test.py
@@ -0,0 +1,471 @@
+"""Tests for borg.legacy.archives (LegacyArchives)."""
+
+from argparse import Namespace
+from datetime import datetime, timezone
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from ..crypto.key import PlaintextKey
+from ..helpers.errors import CommandError, Error
+from ..legacy.archives import LegacyArchives
+from ..legacy.repository import LegacyRepository
+from ..manifest import ArchiveInfo, ArchivesInterface, Manifest
+
+
+# ── helpers ──────────────────────────────────────────────────────────────────────
+
+
+def _id(n):
+    return bytes([n]) * 32
+
+
+TS = "2020-06-01T12:00:00.000000"
+TS2 = "2021-06-01T12:00:00.000000"
+
+
+def _make(entries=()):
+    """Return LegacyArchives with minimal mocks; entries = [(name, id, ts_str), ...]."""
+    repo = MagicMock()
+    manifest = MagicMock()
+    la = LegacyArchives(repo, manifest)
+    for name, id_, ts in entries:
+        la._archives[name] = {"id": id_, "time": ts}
+    return la, repo, manifest
+
+
+def _archive_meta(name, id_, ts=TS, *, username="", hostname="", tags=()):
+    return {
+        "id": id_,
+        "name": name,
+        "time": ts,
+        "exists": True,
+        "username": username,
+        "hostname": hostname,
+        "size": 0,
+        "nfiles": 0,
+        "comment": "",
+        "tags": tags,
+    }
+
+
+def _info(name, id_, ts=TS, *, username="", hostname="", tags=()):
+    from ..helpers.time import parse_timestamp
+
+    return ArchiveInfo(name=name, id=id_, ts=parse_timestamp(ts), tags=tags, user=username, host=hostname)
+
+
+def _make_list_target(infos):
+    """LegacyArchives with _info_tuples replaced so callers get controlled data."""
+    la, repo, manifest = _make([(i.name, i.id, TS) for i in infos])
+    la._info_tuples = lambda deleted=False: iter(infos)
+    return la
+
+
+# ── init / raw-dict operations ───────────────────────────────────────────────────
+
+
+def test_init():
+    la, repo, manifest = _make()
+    assert la._archives == {}
+    assert la.repository is repo
+    assert la.manifest is manifest
+
+
+def test_set_raw_dict_and_get_raw_dict():
+    la, _, _ = _make()
+    d = {"a": {"id": _id(1), "time": TS}}
+    la._set_raw_dict(d)
+    assert la._get_raw_dict() == d
+
+
+def test_prepare():
+    la, repo, manifest = _make()
+    m = MagicMock()
+    m.archives = {"x": {"id": _id(5), "time": TS}}
+    la.prepare(manifest, m)
+    assert la._archives == {"x": {"id": _id(5), "time": TS}}
+
+
+def test_finish():
+    la, _, manifest = _make([("a", _id(1), TS)])
+    result = la.finish(manifest)
+    assert result == {"a": {"id": _id(1), "time": TS}}
+
+
+def test_ids():
+    la, _, _ = _make([("a", _id(1), TS), ("b", _id(2), TS)])
+    assert list(la.ids()) == [_id(1), _id(2)]
+
+
+def test_count():
+    la, _, _ = _make([("a", _id(1), TS), ("b", _id(2), TS)])
+    assert la.count() == 2
+
+
+def test_names():
+    la, _, _ = _make([("a", _id(1), TS), ("b", _id(2), TS)])
+    assert list(la.names()) == ["a", "b"]
+
+
+def test_exists_true():
+    la, _, _ = _make([("a", _id(1), TS)])
+    assert la.exists("a") is True
+
+
+def test_exists_false():
+    la, _, _ = _make()
+    assert la.exists("missing") is False
+
+
+# ── create ───────────────────────────────────────────────────────────────────────
+
+
+def test_create_with_str_ts():
+    la, _, _ = _make()
+    la.create("a", _id(1), TS)
+    assert la._archives["a"] == {"id": _id(1), "time": TS}
+
+
+def test_create_with_datetime_ts():
+    la, _, _ = _make()
+    dt = datetime(2020, 6, 1, 12, 0, 0, tzinfo=timezone.utc)
+    la.create("a", _id(1), dt)
+    assert la._archives["a"]["time"] == dt.isoformat(timespec="microseconds")
+
+
+def test_create_raises_if_exists():
+    la, _, _ = _make([("a", _id(1), TS)])
+    with pytest.raises(KeyError, match="already exists"):
+        la.create("a", _id(2), TS)
+
+
+def test_create_overwrite():
+    la, _, _ = _make([("a", _id(1), TS)])
+    la.create("a", _id(2), TS, overwrite=True)
+    assert la._archives["a"]["id"] == _id(2)
+
+
+# ── get / get_by_id ───────────────────────────────────────────────────────────────
+
+
+def test_get_missing_returns_none():
+    la, _, _ = _make()
+    assert la.get("nope") is None
+
+
+def test_get_returns_archive_info():
+    la, _, _ = _make([("a", _id(1), TS)])
+    info = la.get("a")
+    assert isinstance(info, ArchiveInfo)
+    assert info.name == "a"
+    assert info.id == _id(1)
+
+
+def test_get_raw():
+    la, _, _ = _make([("a", _id(1), TS)])
+    result = la.get("a", raw=True)
+    assert result == {"name": "a", "id": _id(1), "time": TS}
+
+
+def test_get_by_id_missing_returns_none():
+    la, _, _ = _make()
+    assert la.get_by_id(_id(99)) is None
+
+
+def test_get_by_id_returns_archive_info():
+    la, _, _ = _make([("a", _id(1), TS)])
+    info = la.get_by_id(_id(1))
+    assert isinstance(info, ArchiveInfo)
+    assert info.name == "a"
+
+
+def test_get_by_id_raw():
+    la, _, _ = _make([("a", _id(1), TS)])
+    result = la.get_by_id(_id(1), raw=True)
+    assert result == {"name": "a", "id": _id(1), "time": TS}
+
+
+# ── NotImplementedError stubs ──────────────────────────────────────────────────────
+
+
+def test_exists_id_not_implemented():
+    la, _, _ = _make()
+    with pytest.raises(NotImplementedError):
+        la.exists_id(_id(1))
+
+
+def test_exists_name_and_id_not_implemented():
+    la, _, _ = _make()
+    with pytest.raises(NotImplementedError):
+        la.exists_name_and_id("a", _id(1))
+
+
+def test_exists_name_and_ts_not_implemented():
+    la, _, _ = _make()
+    with pytest.raises(NotImplementedError):
+        la.exists_name_and_ts("a", datetime.now())
+
+
+def test_delete_by_id_not_implemented():
+    la, _, _ = _make()
+    with pytest.raises(NotImplementedError):
+        la.delete_by_id(_id(1))
+
+
+def test_undelete_by_id_not_implemented():
+    la, _, _ = _make()
+    with pytest.raises(NotImplementedError):
+        la.undelete_by_id(_id(1))
+
+
+def test_nuke_by_id_not_implemented():
+    la, _, _ = _make()
+    with pytest.raises(NotImplementedError):
+        la.nuke_by_id(_id(1))
+
+
+# ── _get_archive_meta ────────────────────────────────────────────────────────────
+
+
+def test_get_archive_meta_object_not_found():
+    la, repo, _ = _make()
+    repo.get.side_effect = LegacyRepository.ObjectNotFound(_id(1), "/fake/path")
+    result = la._get_archive_meta(_id(1))
+    assert result["exists"] is False
+    assert result["name"] == "archive-does-not-exist"
+    assert result["id"] == _id(1)
+    assert result["tags"] == ()
+
+
+def test_get_archive_meta_success():
+    la, _, manifest = _make()
+    manifest.repo_objs.parse.return_value = (None, b"data")
+    manifest.key.unpack_archive.return_value = {}
+
+    with patch("borg.legacy.archives.ArchiveItem") as mock_ai:
+        item = MagicMock()
+        item.version = 2
+        item.name = "myarchive"
+        item.time = "2021-03-15T10:00:00.000000"
+        item.username = "alice"
+        item.hostname = "myhost"
+        item.get.side_effect = lambda k, d=None: d
+        mock_ai.return_value = item
+
+        result = la._get_archive_meta(_id(1))
+
+    assert result["exists"] is True
+    assert result["name"] == "myarchive"
+    assert result["username"] == "alice"
+    assert result["hostname"] == "myhost"
+
+
+def test_get_archive_meta_bad_version():
+    la, _, manifest = _make()
+    manifest.repo_objs.parse.return_value = (None, b"data")
+    manifest.key.unpack_archive.return_value = {}
+
+    with patch("borg.legacy.archives.ArchiveItem") as mock_ai:
+        item = MagicMock()
+        item.version = 99
+        mock_ai.return_value = item
+
+        with pytest.raises(Exception, match="Unknown archive metadata version"):
+            la._get_archive_meta(_id(1))
+
+
+# ── _infos / _info_tuples ────────────────────────────────────────────────────────
+
+
+def test_infos_and_info_tuples():
+    la, _, _ = _make([("a", _id(1), TS)])
+    la._get_archive_meta = lambda id_: _archive_meta("a", _id(1))
+    infos = list(la._infos())
+    assert len(infos) == 1
+    assert infos[0]["name"] == "a"
+    tuples = list(la._info_tuples())
+    assert len(tuples) == 1
+    assert isinstance(tuples[0], ArchiveInfo)
+    assert tuples[0].name == "a"
+
+
+# ── list ──────────────────────────────────────────────────────────────────────────
+
+
+def test_list_no_filters():
+    info = _info("a", _id(1))
+    la = _make_list_target([info])
+    assert la.list() == [info]
+
+
+def test_list_sort_by_str_raises():
+    la = _make_list_target([_info("a", _id(1))])
+    with pytest.raises(TypeError, match="sequence"):
+        la.list(sort_by="name")
+
+
+def test_list_sort_by():
+    i1 = _info("b", _id(2), TS2)
+    i2 = _info("a", _id(1), TS)
+    la = _make_list_target([i1, i2])
+    result = la.list(sort_by=["name"])
+    assert result == [i2, i1]
+
+
+def test_list_reverse():
+    i1 = _info("a", _id(1))
+    i2 = _info("b", _id(2))
+    la = _make_list_target([i1, i2])
+    assert la.list(reverse=True) == [i2, i1]
+
+
+def test_list_first():
+    infos = [_info(f"a{i}", _id(i + 1)) for i in range(5)]
+    la = _make_list_target(infos)
+    assert la.list(first=3) == infos[:3]
+
+
+def test_list_last():
+    infos = [_info(f"a{i}", _id(i + 1)) for i in range(5)]
+    la = _make_list_target(infos)
+    assert la.list(last=2) == infos[-2:]
+
+
+def test_list_date_filter():
+    i1 = _info("a", _id(1))
+    la = _make_list_target([i1])
+    with patch("borg.legacy.archives.filter_archives_by_date", return_value=[i1]) as mock_filter:
+        result = la.list(older="1d")
+    assert result == [i1]
+    assert mock_filter.called
+
+
+def test_list_match_name():
+    i1 = _info("archive-a", _id(1))
+    i2 = _info("archive-b", _id(2))
+    la = _make_list_target([i1, i2])
+    result = la.list(match=["archive-a"])
+    assert result == [i1]
+
+
+def test_list_match_name_prefix():
+    i1 = _info("archive-a", _id(1))
+    i2 = _info("other", _id(2))
+    la = _make_list_target([i1, i2])
+    result = la.list(match=["name:archive-a"])
+    assert result == [i1]
+
+
+def test_list_match_user():
+    i1 = _info("a", _id(1), username="alice")
+    i2 = _info("b", _id(2), username="bob")
+    la = _make_list_target([i1, i2])
+    assert la.list(match=["user:alice"]) == [i1]
+
+
+def test_list_match_host():
+    i1 = _info("a", _id(1), hostname="laptop")
+    i2 = _info("b", _id(2), hostname="server")
+    la = _make_list_target([i1, i2])
+    assert la.list(match=["host:laptop"]) == [i1]
+
+
+def test_list_match_tags():
+    i1 = _info("a", _id(1), tags=("prod", "db"))
+    i2 = _info("b", _id(2), tags=("dev",))
+    la = _make_list_target([i1, i2])
+    assert la.list(match=["tags:prod"]) == [i1]
+
+
+def test_list_match_aid():
+    from ..helpers.parseformat import bin_to_hex
+
+    i1 = _info("a", _id(1))
+    la = _make_list_target([i1])
+    prefix = bin_to_hex(_id(1))[:4]
+    assert la.list(match=[f"aid:{prefix}"]) == [i1]
+
+
+def test_list_match_aid_ambiguous():
+    from ..helpers.parseformat import bin_to_hex
+
+    i1 = _info("a", _id(1))
+    i2 = _info("b", _id(1))
+    la = _make_list_target([i1, i2])
+    prefix = bin_to_hex(_id(1))[:4]
+    with pytest.raises(CommandError):
+        la.list(match=[f"aid:{prefix}"])
+
+
+# ── get_one ───────────────────────────────────────────────────────────────────────
+
+
+def test_get_one_exact_match():
+    i1 = _info("backup", _id(1))
+    la = _make_list_target([i1])
+    assert la.get_one(["backup"]) == i1
+
+
+def test_get_one_no_match_raises():
+    la = _make_list_target([])
+    with pytest.raises(CommandError, match="matched 0"):
+        la.get_one(["missing"])
+
+
+def test_get_one_multiple_matches_raises():
+    i1 = _info("a", _id(1))
+    i2 = _info("a", _id(2))
+    la = _make_list_target([i1, i2])
+    with pytest.raises(CommandError, match="matched 2"):
+        la.get_one(["a"])
+
+
+# ── list_considering ──────────────────────────────────────────────────────────────
+
+
+def test_list_considering_raises_if_name_set():
+    la, _, _ = _make()
+    args = MagicMock()
+    args.name = "archive"
+    with pytest.raises(Error):
+        la.list_considering(args)
+
+
+def test_list_considering_delegates():
+    i1 = _info("a", _id(1))
+    la = _make_list_target([i1])
+    args = Namespace(
+        name=None,
+        sort_by="name",
+        match_archives=None,
+        first=None,
+        last=None,
+        older=None,
+        newer=None,
+        oldest=None,
+        newest=None,
+        deleted=False,
+    )
+    result = la.list_considering(args)
+    assert result == [i1]
+
+
+# ── ArchivesInterface Protocol / Manifest dispatch ────────────────────────────────
+
+
+def test_legacy_archives_satisfies_archives_interface():
+    la, _, _ = _make()
+    assert isinstance(la, ArchivesInterface)
+
+
+class _FakeLegacyRepo(LegacyRepository):
+    def __init__(self):
+        pass
+
+
+def test_manifest_creates_legacy_archives_for_legacy_repo():
+    repo = _FakeLegacyRepo()
+    key = PlaintextKey(repo)
+    manifest = Manifest(key, repo)
+    assert isinstance(manifest.archives, LegacyArchives)