Both defects came out of Phase 13's acceptance walk, and neither was visible to
any test.
**1. The one-shot rule-group guard was not a guard.** `seedRuleGroup` and
`coreRules.seedGroup` both read their settings stamp, inserted the whole group,
and wrote the stamp AFTER the loop. Two instances booting in the same moment both
read "absent" and both insert -- the walk ended up with 52 module rules where the
module ships 26. `docker compose up --scale app=2` and a rolling restart both
start two instances on purpose, so this is ordinary rather than exotic.
`settings.db` gains `claim(key, value)`: the same `INSERT IGNORE` as
`seedDefault`, reporting its own `affectedRows`, so exactly one caller can win a
key. The atomicity is the PRIMARY KEY's -- no transaction, no lock, the same
bargain `engagementWorker`'s row claim already makes. Both seeders claim before
inserting.
The trade the code already documented is unchanged, only its order: a process
that dies mid-loop leaves the group stamped and partly seeded, and the missing
rules are an operator's visit to the "new rule" form. A duplicate rule is two
mails per event, for every rule in the group, which both functions' own comments
already call the worse outcome.
**Why no test caught it:** the stubs supplied `get` and `set` over a Map, which
cannot race, so they agreed with the bug -- Phase 4a's `foundRows` finding in a
different costume. The fake is now `claim`-shaped and decides without yielding,
exactly as the table does, and both suites gained a test that runs two seeders
with `Promise.all` and asserts one insert each. Verified by reverting the fix:
the module test then reports every rule inserted twice.
**2. A rule that names a `digest` body could not be saved.** `registries.js`
`checkSeedRule` permits `digest` in as many words -- it is the body
`teamDigestWorker` renders for a rule whose email channel an individual set to
digest mode, so it never appears in `channels` and never could -- and
MODULE_API.md 2.4 tells modules they may point `template_keys` at
`notify.digest`. `engagementRules.model.js` then rejected any key that was not
one of the rule's channels.
So every rule shipping a digest body answered an operator who opened it and
pressed Save with a 400 naming a key they had never typed: core's own Team and
news rules, and sixteen of module-uo's. The only way to save was to delete the
digest body, silently dropping digest support from that rule. The two validators
now agree; anything that is neither a channel nor `digest` is still refused, with
a test for each direction.
No MODULE_API bump: no member is added, removed or changed, and the documented
contract is what the code now honours rather than something new.
Co-Authored-By: Claude <noreply@anthropic.com>