A negentropy exchange compares two sets defined by the SAME filter: the relay
builds its side from the filter carried in NEG-OPEN, and this device builds its
side from getNegentropicNostrFeedIds. Any clause we fail to apply locally makes
our set a superset of the relay's, and each extra row comes back as an id the
relay is "missing" -- which this app then queues as a broadcast. Any clause we
apply more tightly makes it a subset, and the difference comes back as ids to
re-download that we already hold. Neither shows up as an error; both show up as a
sync that never settles.
getNegentropicNostrFeedIds was a `when` over the shape of the filter, dispatching
to one of eight hand-written @Query methods. Each method could only bind the
parameters it happened to declare, so the branches disagreed with the filter they
were serving:
- `until` was expressible by NO branch. It is sent to the relay in NEG-OPEN and
was never applied here, so every local event past the requested window was
reported to the relay as one it lacked.
- `since` was strict (`createdAt > :since`) where NIP-01 is inclusive, so an
event stamped exactly on the boundary was a phantom "need" on every pass.
- `kinds && authors` was tested before any tag branch, so a filter carrying
kinds, authors AND tags silently dropped the tags. `kinds && ids` dropped
authors. Every branch dropped whatever it had no parameter for.
- tags were matched with `tags LIKE '%' || :value || '%'` -- a substring scan of
the serialized tag JSON that matches the value in ANY tag position. A pubkey
referenced in an `e` tag counted as a `p` match. And only `tags[name].first()`
was ever bound, so the second and later values of a tag were dropped.
- the reply branch matched `'%' || :eventId || '%reply%'`, which needs the
literal text "reply" to appear somewhere after the id: it misses
`["e","<id>"]` with no marker and false-positives on any later tag containing
the word.
- the `else` branch ignored the filter's kinds entirely and substituted
`arrayOf(TextNoteEvent.KIND)`. A filter with only authors, or only tags, got a
local set of kind-1 notes -- unrelated to what the relay was reconciling.
- more than one filter returned emptyList() with a "not yet supported" warning.
That is the worst available answer: an empty local set tells the relay we hold
none of these events, so it hands back its entire set as ids to download.
- the limit branches ordered `createdAt ASC LIMIT n`, returning the OLDEST n
where a relay answering a limited filter returns the newest.
## The replacement
NostrEventFilterQuery translates a SynchronizationFilter into one SQL statement
that applies every clause, and NostrEventDao.getNostrEventsMatchingFilter runs it
as a @RawQuery. Raw because a nostr filter is a variable set of constraints over
variable-length lists, which is precisely what @Query cannot express -- and what
drove the per-shape methods that dropped constraints in the first place.
Semantics follow quartz's FilterMatcher, which is what the relays this app talks
to implement: membership for ids/authors/kinds; AND between tag names and OR
between the values of one name for `tags`; AND both ways for `tagsAll`; inclusive
`since`/`until`; and a present-but-empty list matches nothing.
Tags are matched by looking for the `["<name>","<value>"` fragment, built by
encoding through the same serializer that wrote the column so escaping agrees,
with `%`/`_`/`\` escaped and `ESCAPE '\'` on the LIKE so a wildcard inside a value
cannot widen the match. Anchoring on the tag name and on the closing quote of the
value is what keeps a hex string from matching in an unrelated tag position.
Multiple filters are now the union of their matches, de-duplicated by id.
## The Marmot branch is kept, and narrowed
Group messages still answer from MarmotGroupEvent: that table carries the NIP-40
expiry a relay uses to decide whether it still serves an event, and an indexed
chatRoomId instead of a scan of the tags JSON. But the branch now only claims a
filter it can fully honour -- exactly kind 445, an `h` tag, and nothing else --
because it answers from a different table and would otherwise reproduce the same
silently-dropped-constraint bug it is an exception to. It also fills in the `h`
tag and the real signature on the NostrEvent it synthesizes rather than leaving
them empty.
## Tests
NostrEventFilterQueryTest pins the generated SQL and the bound values for each
clause, including tag escaping and the empty-list case. It asserts the
translation rather than eyeballing it, because a dropped clause is not an error
at runtime -- it is reconciliation quietly reporting differences that are not
real.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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