# Graph compatibility notes

Checked against the original at `../orly` (`pkg/database/graph-*.go`,
`pkg/database/save-event.go`, `pkg/database/delete-event.go` and
`pkg/database/indexes/keys.go`), and morly's `pkg/store/index/keys.mx`.

## Matches

- `pks`, `spk`, `epg`, `peg`, `eeg`, `gee`, `ppg`, `gpp` key prefixes, field
  order, widths and direction bytes.
- Author edge `0`; outbound p-tag edge `1`; inbound reverse `2`.
- E-tag out `0`, in `1`; pubkey-pubkey out `0`, in `1`.
- Author and p-tag event→pubkey edges, the reverse pubkey→event edges, and the
  direct pubkey→pubkey edges written from every p-tag.
- E-tag event→event edges only when the target event is stored, written in both
  directions.
- `pp` traversal is a BFS over kind-3 `ppg`/`gpp` edges.
- `pe` traversal is the original one-hop authored / p-tag-mention query.
- `ee` is seeded from the events authored by the supplied pubkey.

## Intentional corrections

- **Reverse p-tag deletion.** orly's `deleteGraphIndexes` copies the forward
  direction byte when constructing the reverse `peg` key, so a p-tag edge with
  direction 1 constructs another `peg` direction 1 instead of direction 2.
  torly constructs the actual reverse (`DirPTagIn`).
- **`pe` result shape.** orly's executor puts event IDs into
  `pubkeys_by_depth` for outbound `pe`. torly always reports event IDs in
  `events_by_depth`.
- **`ee` direction.** orly's executor passes `out`, `in` or `both` to
  `TraverseThread`, which only recognizes `outbound`, `inbound` or `both`;
  consequently its `out` and `in` return nothing. torly maps `out` to `eeg`,
  `in` to `gee`, and `both` to the union.
- **Complete kind coverage.** orly's `GetEventsByAuthor` and
  `GetEventsReferencingPubkey` use a short common-kind list when no kinds are
  requested. torly scans all kinds.

## Deliberate differences

- Events with more than **256** `p`/`e` tags are not graph-indexed at all.
  Truncating them would silently change the graph, so they contribute no
  author, p-tag or e-tag edges. They remain stored and queryable through the
  normal NIP-01 indexes.
- `ee` treats every event authored by the seed as a root and excludes all of
  them from the response. orly excludes only the current root, so an authored
  event referenced by another root can appear in its result.
- torly backfills an e-tag edge when a reply is stored before its root. orly
  only creates the edge if the target already exists.
- A graph response is sorted per depth for deterministic output; orly emits
  discovery order.

The deployed orly relay currently reports `graph queries not supported on this
relay` because its graph executor is not initialized, so runtime comparison of
`_graph` was not possible against that instance; the comparison above is
against the source implementation.