# meta-feeder-usenet

Usenet feeder sidecar for the MetaMesh gateway tier. Bridges a Usenet header
scan **we run ourselves** (an [nntmux](https://github.com/NNTmux/newznab-tmux)
sidecar) into the MetaMesh network.

## Why this exists

`meta-feeder-indexer` proxies an **external** Newznab indexer and mints an
`nzb-release` (`0x1005`) cid that embeds *that indexer's host*. Only a peer
holding that indexer's credential can ever redeem it — so the metadata half of
Usenet is neither self-owned nor portable.

Scanning Usenet ourselves gives us the article Message-IDs for free at collation
time (no grab, no scrape). That lets this feeder mint a **portable**
`nzb-posting` (`0x1003`) cid — a digest over the Message-ID set, embedding no
host — which **any peer with a plain NNTP provider can redeem, with no indexer
credential anywhere in the path**.

This feeder **adds** a Usenet metadata source alongside `meta-feeder-indexer`.
It replaces nothing; a gateway query fans out to both.

Design record:
`meta-gateway/docs/others/self-hosted-usenet-indexer-study.md`.

## Shape

```
[nntmux sidecar: PHP + MariaDB + Redis]     [usenet-feeder: Rust, FeederPlugin]
  header-scan groups (few conns)   ──►  reads `releases` (searchname/size/guid)
  collate → releases               ──►  gunzips <nzb_root>/<c>/<guid>.nzb.gz
  writes <guid>.nzb.gz             ──►  mints 0x1003 from the Message-ID set
  (CBP purged; the gz is the only  ──►  emits the record + a relative
   durable home of the msg-ids)          `manifest_url` onto its own /blob route
                                                    │
                                                    ▼
   gateway core: seeds the .nzb as an ORDINARY sha2-256 IPFS cid, publishes it
   as a fileType=nzb meta-core record, rewrites the field to that cid
   (the same path posters take — `remote_feeder.rs` SEEDABLE_FIELDS)
                                                    │
                                                    ▼
   meta-share: resolve `manifest` cid (blockstore / bitswap / ANY holder) →
   NzbManifest::from_nzb_xml → BODY-fetch each Message-ID from ANY plain NNTP
   provider → materialise → play
```

The sidecar is **persistent cache, cheap to lose** — everything in it is
re-derivable by re-scanning. Same pattern as the Tribler sidecar: stateful
upstream, but the gateway still sees a stateless HTTP feeder.

Like every feeder this one is **meta-core-free and blockstore-free**: it finds
records and serves bytes; the core owns hashing-into-the-blockstore, the
meta-core store-back, and the libp2p wire (gateway invariant 10).

## Configuration

Operator config lives on the **feeder**, not the gateway (invariant 12). Set it
on the plugin's config page in the gateway dashboard; the env vars below are a
**first-boot seed only** — the persisted `config.json` wins on the next restart,
and there is no hot reload.

| Field | Env seed | What |
|---|---|---|
| `db_url` | `NNTMUX_DB_URL` | MariaDB DSN of nntmux's catalog, e.g. `mysql://nntmux:secret@nntmux-db:3306/nntmux`. Blank → the upstream soft-skips and the plugin reports Degraded. |
| `nzb_root` | `NNTMUX_NZB_PATH` | nntmux's NZB directory **as mounted into this container**. Must be the same volume nntmux's `PATH_TO_NZBS` points at, or every release resolves to `NotFound`. |

Infra env: `META_FEEDER_HTTP_LISTEN` (default `0.0.0.0:8080`),
`META_FEEDER_STATE_DIR` (default `/data/meta-feeder`), `RUST_LOG`.

Scan policy — which groups, backfill depth, scan interval, connection budget —
is the **gateway maintainer's** call and is configured on the nntmux sidecar.
Keep the connection budget conservative: the scanner and playback draw on the
same provider slots, so a greedy value does not merely over-scan, it stalls
playback mid-stream.

## Build

```bash
cargo build --release --bin usenet-feeder
cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings

docker build -f feeder-plugin/usenet-feeder/Dockerfile -t ghcr.io/worph/meta-feeder-usenet:dev .
```

`crates/meta-feeder-sdk/` is a **vendored copy** of the SDK, mirrored from
`meta-gateway`. Independent submodules cannot share a cargo path-dep, so keep it
in step when the SDK changes — in particular `hash.rs`'s
`compute_nzb_posting_cid`, whose normalisation rule is the dedup contract and is
mirrored again on the meta-share side.

## Gotchas

- **An empty catalog is the visible symptom of both nntmux silent-zero traps**:
  an empty `PATH_TO_NZBS` (set-but-empty beats the default, so `createNZBs()`
  aborts and you get 0 releases with no error), and seeded groups left
  `active=0`. The plugin logs a loud warning when `releases` is empty at boot —
  believe it.
- **The Message-IDs are not in the database.** nntmux purges
  collections/binaries/parts right after writing each NZB, so the on-disk
  `.nzb.gz` is the only durable home. A wrong `nzb_root` therefore fails at
  `compute_outcomes`, not at query time.