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).
