Implements the filesystem-backed rule store body left empty at contract
phase: YAML parse + Pydantic validation, asyncinotify watch over
./rules/ttp/, in-process state cache with auto-revert on expires_at,
and a subscribe_changes() async iterator yielding one RuleChange per
per-rule edit. Bus topic builders ttp_rule_reloaded / ttp_rule_state
ship alongside.
Why: the rule plane needed a store before the engine (E.3.7) could
consume RuleChange events and atomically swap compiled rules into its
dispatch index.
Notes:
- Linux-only by construction (asyncinotify wheel gated by sys_platform
marker; FilesystemRuleStore.__init__ raises on non-Linux).
- Filename allowlist is the FIRST check on every inotify event.
- Content-hash dedup so a single write firing IN_CREATE + IN_CLOSE_WRITE
produces exactly one RuleChange.
- All compile work serializes on a single asyncio.Lock.
- Subscribers register their queue eagerly so events fired between
subscribe_changes() and the first __anext__() are buffered.
xfails flipped: per-save-style + filter-ordering + atomic-swap in
test_filesystem.py; load_compiled / set_state isolation / round-trip /
per-rule fan-out / expired-state revert / set_state failure semantics
in test_conformance.py (FS side; DB side stays xfail until E.3.6);
malformed-YAML compile-time check in test_rule_engine.py.
Tests: 197 passed, 35 xfailed (gated on E.3.6 / E.3.7 / lifters).
mypy + bandit: clean on all touched files.
Wiki update for the per-rule reload + state-change topics lands in a
matching wiki-checkout/Service-Bus.md edit (separate repo).
Adds decnet/ttp/store/ subpackage:
- base.py: RuleState frozen dataclass, RuleChange NamedTuple, RuleStore ABC
- factory.py: get_rule_store() reading DECNET_TTP_RULE_STORE_TYPE
- impl/filesystem.py: FilesystemRuleStore with sys.platform=='linux'
fail-fast guard, allowlist filename regex, raw inotify mask bits
(lib import deferred to E.3 so contract phase compiles without the
asyncinotify dep installed)
- impl/database.py: DatabaseRuleStore stub (no platform guard)
TTPRule + TTPRuleState SQLModels were already shipped at E.1.1; this
commit closes the type-only TYPE_CHECKING forward-ref in
rule_engine.py via real runtime imports through the new package.
Third and fourth TTP-tagging contract commits, plus a scoped subset
of the E.2.4 conformance tests covering the contract surface shipped
here (full hypothesis-fuzz suite still lands with E.2.4).
E.1.3 — decnet/ttp/base.py
- TaggerEvent NamedTuple: source_kind, source_id, attacker_uuid,
identity_uuid, session_id, decky_id, opaque payload.
- Tagger(ABC) with abstract async tag(); class-level name and
HANDLES: frozenset[str] (default empty so a misconfigured subclass
is loudly idle, not loudly noisy).
- TolerantTagger(Tagger): concrete tag() wraps abstract _tag_impl()
in try/except Exception (deliberately not BaseException — so
KeyboardInterrupt / SystemExit / asyncio.CancelledError propagate
and the worker can shut down cleanly). Swallowed exceptions log
at WARNING with exc_info, never ERROR — absence is the steady
state, not a bug. Subclasses override _tag_impl, never tag — the
tolerance contract is enforced in the base class, not on trust.
- KNOWN_SOURCE_KINDS: Final[frozenset[str]] enumerating every
source_kind a producer is allowed to emit. Closed-by-enumeration
at the runtime layer; the composite tagger keys its WARNING/INFO
bridge off this constant to surface the silent-drop trap from
the design doc (lines 160–195).
E.1.4 — decnet/ttp/factory.py
- get_tagger() reads DECNET_TTP_TAGGER_TYPE (default 'composite');
unknown values raise ValueError with the known-list. Mirrors
decnet.intel.factory and decnet.clustering.factory.
- _KNOWN = ('composite',). Per-lifter classes (E.1.6) are children
of the composite, not standalone tagger types.
- CompositeTagger(Tagger): pre-computes a dict[str, list[Tagger]]
dispatch index from each lifter's HANDLES; fans events out
concurrently with asyncio.gather and concatenates results.
Empty lifters=[] is the legal contract-phase state — E.1.6
wires the real lifters in.
- Unhandled-event observability: source_kind in KNOWN_SOURCE_KINDS
but no lifter claims it -> WARNING once per kind per process
(missed E.1.6 update). Unknown kind -> INFO once per kind per
process (future-feature telemetry, by design). Per-process dedup
via plain set; E.1.6 may swap in a proper rate-limiter once
production traffic shapes are known.
Tests — tests/ttp/test_base.py, tests/ttp/test_factory.py
- Tagger / TolerantTagger abstractness, missing-tag-impl rejection,
WARNING-not-ERROR log level, propagation of KeyboardInterrupt /
SystemExit / asyncio.CancelledError.
- Factory env-var routing, unknown-name ValueError, dispatch-index
correctness, only-claiming-lifter invocation, WARNING-once for
known-but-unclaimed kinds, INFO-once for unknown kinds, result
concatenation across lifters.
Mypy clean under .311/bin/mypy --ignore-missing-imports.
