diff --git a/tests/ttp/store/__init__.py b/tests/ttp/store/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/ttp/store/conftest.py b/tests/ttp/store/conftest.py
new file mode 100644
index 00000000..5a218cf8
--- /dev/null
+++ b/tests/ttp/store/conftest.py
@@ -0,0 +1,47 @@
+"""Parametrized ``rule_store`` fixture for E.2.14b.
+
+The conformance contract from ``development/TTP_TAGGING.md`` §E.2.14b:
+both backends — :class:`FilesystemRuleStore` and
+:class:`DatabaseRuleStore` — must satisfy the same observable
+behavior. Tests that consume :func:`rule_store` are run twice, once
+per backend.
+
+Filesystem is skipped on non-Linux (it raises ``RuntimeError`` from
+``__init__`` on macOS / Windows because the inotify dep is
+Linux-only).
+"""
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+from typing import Iterator
+
+import pytest
+
+from decnet.ttp.store.base import RuleStore
+from decnet.ttp.store.impl.database import DatabaseRuleStore
+from decnet.ttp.store.impl.filesystem import FilesystemRuleStore
+
+
+@pytest.fixture(
+    params=["filesystem", "database"],
+    ids=["filesystem", "database"],
+)
+def rule_store(
+    request: pytest.FixtureRequest, tmp_path: Path,
+) -> Iterator[RuleStore]:
+    """Yield a fresh :class:`RuleStore` instance per parametrization.
+
+    The filesystem backend is constructed against a ``tmp_path``
+    rules dir so tests never touch the real ``./rules/``. The
+    database backend's connection wiring lands at E.3.6; today the
+    fixture just hands out the raw class instance and impl-phase
+    tests are responsible for plumbing it into a session.
+    """
+    backend = request.param
+    if backend == "filesystem":
+        if sys.platform != "linux":
+            pytest.skip("FilesystemRuleStore requires Linux (inotify)")
+        yield FilesystemRuleStore(rules_dir=tmp_path)
+    else:
+        yield DatabaseRuleStore()
diff --git a/tests/ttp/store/test_conformance.py b/tests/ttp/store/test_conformance.py
new file mode 100644
index 00000000..19f4d76a
--- /dev/null
+++ b/tests/ttp/store/test_conformance.py
@@ -0,0 +1,173 @@
+"""E.2.14b — Cross-backend conformance for :class:`RuleStore`.
+
+Both :class:`FilesystemRuleStore` and :class:`DatabaseRuleStore` must
+satisfy the same observable contract. The :func:`rule_store` fixture
+in :mod:`conftest` parametrizes every assertion in this module over
+both backends.
+
+Per ``development/TTP_TAGGING.md`` §E.2.14b:
+
+* :meth:`load_compiled` over a known YAML corpus returns the same
+  ``CompiledRule`` set from both backends (modulo state defaulting
+  to enabled when no state row exists).
+* :meth:`get_state` for an unknown ``rule_id`` returns the default
+  ``RuleState(state="enabled", ...)`` — never raise, never return
+  ``None``.
+* :meth:`set_state` on one ``rule_id`` does not affect any other.
+* :meth:`set_state` followed by :meth:`get_state` round-trips
+  faithfully.
+* :meth:`subscribe_changes` yields ONE :class:`RuleChange` per
+  per-rule edit (5-rule edit → 5 events, never one batch of 5).
+* ``expires_at`` in the past → :meth:`get_state` returns the
+  default and emits a ``ttp.rule.state.{rule_id}`` auto-revert
+  event.
+* :meth:`set_state` failure (DB write error) raises rather than
+  silently dropping — operational state changes are not a
+  tolerated-absence path.
+
+Filesystem-specific properties (inotify mask, dotfile filter,
+atomic-swap concurrency) live in :mod:`test_filesystem`.
+"""
+from __future__ import annotations
+
+import inspect
+
+import pytest
+
+from decnet.ttp.store.base import RuleChange, RuleState, RuleStore
+
+
+# ── Surface (GREEN today) ───────────────────────────────────────────
+
+
+def test_store_implements_required_methods(rule_store: RuleStore) -> None:
+    """Every backend implements all four ABC methods. Catches a
+    refactor that accidentally drops a method body."""
+    for name in ("load_compiled", "get_state", "set_state", "subscribe_changes"):
+        assert hasattr(rule_store, name)
+
+
+def test_async_methods_are_coroutines() -> None:
+    """The three ``async def`` methods on the ABC are coroutine
+    functions; ``subscribe_changes`` is a regular ``def`` returning
+    an async iterator (per the doc's signature)."""
+    for name in ("load_compiled", "get_state", "set_state"):
+        member = getattr(RuleStore, name)
+        assert inspect.iscoroutinefunction(member), (
+            f"RuleStore.{name} must be `async def`"
+        )
+
+
+def test_rule_change_namedtuple_shape() -> None:
+    """:class:`RuleChange` carries ``change_kind``, ``rule_id``,
+    ``new_value`` — pinned so a future "improvement" that adds
+    fields trips downstream consumers (the bus republisher, the
+    engine's atomic swap path) deliberately rather than silently."""
+    assert RuleChange._fields == ("change_kind", "rule_id", "new_value")
+
+
+# ── Default state behavior ──────────────────────────────────────────
+
+
+async def test_get_state_unknown_returns_default(rule_store: RuleStore) -> None:
+    """``get_state`` for a never-set ``rule_id`` returns the default
+    ``RuleState`` — never raises, never returns ``None``.
+
+    GREEN for :class:`FilesystemRuleStore` (the impl already returns
+    ``RuleState()`` for an empty cache; covered in the contract
+    file). xfail for :class:`DatabaseRuleStore` until E.3.6 lands.
+    """
+    if type(rule_store).__name__ == "DatabaseRuleStore":
+        pytest.xfail("impl phase E.3.6 — DatabaseRuleStore.get_state")
+    state = await rule_store.get_state("R0001_unknown_rule")
+    assert state == RuleState()
+    assert state.state == "enabled"
+
+
+# ── Behavioral conformance (xfail until E.3.5/E.3.6) ────────────────
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5/E.3.6 — load_compiled lands with each "
+    "backend's parse-and-compile implementation",
+)
+async def test_load_compiled_corpus_identical_across_backends(
+    rule_store: RuleStore,
+) -> None:
+    """Both backends, given the same YAML corpus, return the same
+    set of ``CompiledRule`` (modulo state defaulting). The doc's
+    cross-backend property requires running the same fixture against
+    both — pinned here as a single test that the parametrize fans
+    out over both backends."""
+    pytest.fail("load_compiled not yet implemented")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5/E.3.6 — set_state lands with each "
+    "backend's persistence implementation",
+)
+async def test_set_state_isolates_rules(rule_store: RuleStore) -> None:
+    """``set_state(A, ...)`` does not perturb the state read by
+    ``get_state(B)``. Catches a refactor that accidentally writes
+    a global cache key."""
+    pytest.fail("set_state not yet implemented")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5/E.3.6 — set_state round-trip lands with "
+    "each backend's persistence implementation",
+)
+async def test_set_state_then_get_state_round_trips(
+    rule_store: RuleStore,
+) -> None:
+    """``set_state`` followed by ``get_state`` returns the value
+    that was set. No translation, no field drop."""
+    pytest.fail("set_state round-trip not yet implemented")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5/E.3.6 — subscribe_changes incremental "
+    "fan-out lands with each backend's watch implementation",
+)
+async def test_subscribe_changes_per_rule_not_batched(
+    rule_store: RuleStore,
+) -> None:
+    """A 5-rule edit produces 5 :class:`RuleChange` events from
+    :meth:`subscribe_changes`, never a single event carrying 5
+    entries. The bus per-rule fan-out
+    (``ttp.rule.reloaded.{rule_id}``) inherits its granularity from
+    this iterator."""
+    pytest.fail("subscribe_changes not yet implemented")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5/E.3.6 — expires_at auto-revert + "
+    "ttp.rule.state.{rule_id} emission land with each backend impl",
+)
+async def test_expired_state_reverts_to_default_and_emits(
+    rule_store: RuleStore,
+) -> None:
+    """A ``RuleState`` with ``expires_at`` in the past returns the
+    default from :meth:`get_state` AND emits a
+    ``ttp.rule.state.{rule_id}`` auto-revert event."""
+    pytest.fail("expires_at auto-revert not yet implemented")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5/E.3.6 — set_state failure semantics "
+    "(raise, never silently drop) land with each backend impl",
+)
+async def test_set_state_failure_raises_not_silent(
+    rule_store: RuleStore,
+) -> None:
+    """A backend failure during :meth:`set_state` (e.g. DB write
+    error, disk full) MUST raise rather than silently drop.
+    Operational state changes are NOT a tolerated-absence path —
+    state drift would be silent and dangerous."""
+    pytest.fail("set_state failure semantics not yet implemented")
diff --git a/tests/ttp/store/test_database.py b/tests/ttp/store/test_database.py
new file mode 100644
index 00000000..1f735e57
--- /dev/null
+++ b/tests/ttp/store/test_database.py
@@ -0,0 +1,80 @@
+"""E.2.14b — Database-specific RuleStore properties.
+
+Per ``development/TTP_TAGGING.md`` §E.2.14b: the database backend's
+tests run against BOTH SQLite and MySQL via the ``db_backends``
+fixture in :mod:`tests.web.db.conftest`. Today the database store's
+methods raise ``NotImplementedError`` so most assertions xfail.
+
+The cross-backend conformance assertions (load_compiled equality,
+get_state default, set_state isolation/round-trip,
+subscribe_changes per-rule fan-out, expires_at auto-revert) live in
+:mod:`test_conformance` and run against this backend automatically
+via the parametrized ``rule_store`` fixture in :mod:`conftest`.
+
+This module pins behavior that's *only* meaningful for the database
+backend — specifically the propagation of state via the underlying
+``ttp_rule_state`` table, which conformance tests exercise but don't
+introspect at the SQL level.
+"""
+from __future__ import annotations
+
+import inspect
+
+import pytest
+
+from decnet.ttp.store.impl.database import DatabaseRuleStore
+
+
+def test_database_store_constructs_without_platform_guard() -> None:
+    """Unlike the filesystem backend, the database store has no
+    platform restriction — a macOS / Windows operator who set
+    ``DECNET_TTP_RULE_STORE_TYPE=database`` MUST be able to import
+    and construct the class without hitting an import-time error.
+    Pinned because regressing this would re-block non-Linux
+    contributors from running the suite at all."""
+    store = DatabaseRuleStore()
+    assert store is not None
+
+
+def test_database_store_implements_abc() -> None:
+    """All four ABC methods are defined on the concrete class —
+    not inherited as abstract. Catches a refactor that accidentally
+    drops a method body without removing the ``@abstractmethod``
+    decorator from the ABC."""
+    for name in ("load_compiled", "get_state", "set_state", "subscribe_changes"):
+        member = getattr(DatabaseRuleStore, name)
+        assert not getattr(member, "__isabstractmethod__", False)
+
+
+def test_async_methods_are_coroutines() -> None:
+    for name in ("load_compiled", "get_state", "set_state"):
+        member = getattr(DatabaseRuleStore, name)
+        assert inspect.iscoroutinefunction(member)
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.6 — DatabaseRuleStore needs to write "
+    "into ttp_rule_state via the repository session; today the "
+    "method body raises NotImplementedError",
+)
+async def test_set_state_writes_to_ttp_rule_state_table() -> None:
+    """``set_state`` writes / upserts a row in the ``ttp_rule_state``
+    table. After the write, a fresh ``DatabaseRuleStore`` instance
+    sees the same value via :meth:`get_state` (state survives
+    process restart — that's the whole point of the database
+    backend over the filesystem one)."""
+    pytest.fail("DatabaseRuleStore.set_state not yet implemented")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.6 — master-side filesystem→DB sync of "
+    "ttp_rule lands with the swarm-mode wiring",
+)
+async def test_filesystem_to_db_sync_populates_ttp_rule() -> None:
+    """In swarm mode, the master watches ``./rules/ttp/`` and
+    syncs each YAML edit into the ``ttp_rule`` table; workers
+    tail the DB. This test pins the half of the contract that
+    only the database backend implements."""
+    pytest.fail("master-side fs→DB sync not yet implemented")
diff --git a/tests/ttp/store/test_filesystem.py b/tests/ttp/store/test_filesystem.py
new file mode 100644
index 00000000..456cfe42
--- /dev/null
+++ b/tests/ttp/store/test_filesystem.py
@@ -0,0 +1,221 @@
+"""E.2.14b — Filesystem-specific RuleStore properties.
+
+Pins behavior that's unique to :class:`FilesystemRuleStore`:
+
+* Inotify event mask covers four save styles (``IN_CLOSE_WRITE``,
+  ``IN_MOVED_TO``, ``IN_CREATE``, ``IN_DELETE``) per ``strace`` of
+  vim and other editors. Verified by parametrizing each case and
+  asserting one event per save.
+* Filename allowlist (vs denylist) — dotfile / scratch / wrong-ext
+  filenames produce zero events and zero loaded rules; the positive
+  sibling case still loads.
+* CLOSE_WRITE on a filtered name produces NEITHER a parse attempt
+  NOR a log line. The filter is the first thing the event handler
+  checks; observability noise on every vim save would be its own
+  bug.
+* Atomic-swap concurrency: parallel edits compile in a serialized
+  stream; concurrent :meth:`evaluate` sees only fully-frozen
+  ``CompiledRule`` (NamedTuple, mutation-resistant).
+
+Skipped wholesale on non-Linux (the store class refuses to construct
+without inotify). Most behavioral assertions xfail-gated behind
+E.3.5; the constants and immutability properties are GREEN today.
+"""
+from __future__ import annotations
+
+import re
+import sys
+
+import pytest
+
+from decnet.ttp.impl.rule_engine import CompiledRule
+from decnet.ttp.store.base import RuleState
+from decnet.ttp.store.impl import filesystem as fs
+
+pytestmark = pytest.mark.skipif(
+    sys.platform != "linux",
+    reason="FilesystemRuleStore is Linux-only (inotify dep)",
+)
+
+
+# ── Constants (GREEN today) ─────────────────────────────────────────
+
+
+def test_inotify_mask_covers_four_save_styles() -> None:
+    """The mask is the bitwise OR of IN_CLOSE_WRITE | IN_MOVED_TO |
+    IN_CREATE | IN_DELETE. Each bit covers one canonical save style.
+    Pinning the OR pins the contract: a future contributor cannot
+    quietly drop a bit (and silently miss an editor's save mode).
+    """
+    expected = (
+        fs._IN_CLOSE_WRITE
+        | fs._IN_MOVED_TO
+        | fs._IN_CREATE
+        | fs._IN_DELETE
+    )
+    assert fs._INOTIFY_MASK == expected
+    # Each bit must actually be set in the composite.
+    for bit in (
+        fs._IN_CLOSE_WRITE,
+        fs._IN_MOVED_TO,
+        fs._IN_CREATE,
+        fs._IN_DELETE,
+    ):
+        assert fs._INOTIFY_MASK & bit
+
+
+def test_inotify_mask_uses_canonical_kernel_values() -> None:
+    """Bit values match ``<sys/inotify.h>``. Sanity check against
+    accidental endianness / byte-shuffle bugs in the inlined
+    constants. Real values from man inotify(7).
+    """
+    assert fs._IN_CLOSE_WRITE == 0x00000008
+    assert fs._IN_MOVED_TO == 0x00000080
+    assert fs._IN_CREATE == 0x00000100
+    assert fs._IN_DELETE == 0x00000200
+
+
+# ── Filename allowlist (GREEN today) ────────────────────────────────
+
+
+@pytest.mark.parametrize(
+    "filename",
+    [
+        ".T1110_brute_force.yaml.swp",      # vim swap
+        ".T1110_brute_force.yaml.swo",      # secondary vim swap
+        "T1110_brute_force.yaml~",           # tilde backup
+        ".T1110_brute_force.yaml.bak",       # dot-prefix backup
+        "4913",                              # vim atomic-save probe
+        ".4913",                             # dot-prefix variant
+        ".foo",                              # any dotfile, no yaml
+        "T1110_brute_force.yaml.tmp",        # wrong extension
+        "T1110_brute_force.txt",             # right shape, wrong ext
+    ],
+)
+def test_scratch_filenames_rejected_by_allowlist(filename: str) -> None:
+    """Dotfile / scratch / wrong-extension filenames fail the
+    allowlist regex.
+
+    Listed exhaustively (rather than property-tested) because the
+    allowlist's *exclusion* set is the load-bearing surface — a
+    future "let's also accept .yaml.tmp" PR must trip this test
+    deliberately.
+    """
+    assert fs._VALID_RULE_FILENAME.fullmatch(filename) is None
+
+
+@pytest.mark.parametrize(
+    "filename",
+    [
+        "T1110_brute_force.yaml",
+        "T1078.yaml",
+        "T1059_command_and_scripting.yml",
+        "R0001.yaml",
+    ],
+)
+def test_valid_rule_filenames_accepted(filename: str) -> None:
+    """Positive cases: real rule files are accepted by the allowlist
+    regex. Confirms the filter excludes scratch files without
+    false-rejecting real ones."""
+    assert fs._VALID_RULE_FILENAME.fullmatch(filename) is not None
+
+
+def test_filename_allowlist_uses_fullmatch_semantics() -> None:
+    """The pattern uses ``\\Z`` / ``fullmatch`` — anchoring is
+    load-bearing. ``foo.yaml.tmp`` would match a non-anchored
+    ``.yaml`` substring search but is correctly rejected by
+    ``fullmatch``. Pinning the regex's anchor behavior catches a
+    refactor to ``re.search`` that would silently widen the
+    allowlist."""
+    # The compiled pattern as authored doesn't carry trailing $
+    # because fullmatch implicitly anchors. The string we test
+    # passes a no-anchor `search` but fails `fullmatch`.
+    assert re.compile(fs._VALID_RULE_FILENAME.pattern).search(
+        "T1110_brute_force.yaml.tmp",
+    ) is not None
+    assert fs._VALID_RULE_FILENAME.fullmatch(
+        "T1110_brute_force.yaml.tmp",
+    ) is None
+
+
+# ── Construction guard (GREEN today) ────────────────────────────────
+
+
+def test_construct_with_tmp_path_works(tmp_path) -> None:
+    """The constructor accepts an explicit ``rules_dir`` so tests
+    can sandbox without touching the real ``./rules/``."""
+    store = fs.FilesystemRuleStore(rules_dir=tmp_path)
+    assert store._rules_dir == tmp_path
+
+
+# ── CompiledRule immutability (GREEN today) ─────────────────────────
+
+
+def test_compiled_rule_is_frozen() -> None:
+    """``CompiledRule`` is a :class:`NamedTuple`, so field
+    assignment raises ``AttributeError``. The doc references
+    ``FrozenInstanceError`` (the dataclass equivalent), but the
+    actual implementation uses NamedTuple — the in-test smoke
+    signal is the same property (mutation-resistant) under a
+    different exception type. Pinning the AttributeError behavior
+    here clarifies the contract for future readers."""
+    rule = CompiledRule(
+        rule_id="R0001",
+        rule_version=1,
+        name="test",
+        applies_to=frozenset({"attacker_command"}),
+        match_spec={},
+        emits=(("T1110", None),),
+        evidence_fields=(),
+        state=RuleState(),
+    )
+    with pytest.raises(AttributeError):
+        rule.rule_id = "tampered"  # type: ignore[misc]  # deliberate mutation attempt
+
+
+# ── Inotify save-style coverage (xfail until E.3.5) ─────────────────
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5 — inotify event loop lands with the FS "
+    "store implementation; per-save-style assertions wait on it",
+)
+@pytest.mark.parametrize("save_style", ["close_write", "moved_to", "create", "delete"])
+async def test_each_save_style_yields_exactly_one_event(
+    save_style: str,
+) -> None:
+    """Each of the four save styles produces exactly one
+    :class:`RuleChange` event from :meth:`subscribe_changes`. xfail
+    until the inotify event loop lands at E.3.5."""
+    pytest.fail(f"inotify event loop not yet implemented ({save_style})")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5 — scratch-file filter wired into the "
+    "event handler lands with the FS store implementation",
+)
+async def test_close_write_on_filtered_name_emits_no_log_line() -> None:
+    """A CLOSE_WRITE event on a name failing the allowlist (e.g.
+    ``.foo.yaml.swp``) produces NEITHER a parse attempt NOR a log
+    line. The filter is the FIRST thing the event handler checks;
+    observability noise on every vim save would be its own bug."""
+    pytest.fail("event handler filter ordering not yet implemented")
+
+
+# ── Atomic-swap concurrency (xfail until E.3.5) ─────────────────────
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.5 — atomic per-rule swap + serialized "
+    "compile lands with the FS store implementation",
+)
+async def test_atomic_swap_serializes_compile() -> None:
+    """N parallel asyncio tasks editing distinct rule files compile
+    in a single ordered stream — no two intervals overlap on an
+    instrumented engine. Concurrent :meth:`RuleEngine.evaluate`
+    calls during the edit storm see only fully-frozen
+    ``CompiledRule`` values, never a torn intermediate."""
+    pytest.fail("atomic-swap concurrency not yet implemented")