lez-indexer-module/README.md

# Logos Execution Zone Indexer Module

A Logos Core **service module** (`type: core`) that runs the Logos Execution Zone
(L2) indexer and exposes it to the Logos ecosystem. It is a thin Qt plugin around
the `indexer_ffi` library from
[`logos-execution-zone`](https://github.com/logos-blockchain/logos-execution-zone):
it starts the indexer, which connects to an L1/bedrock node, indexes the zone's
channel, and serves queries over an RPC (WebSocket) server.

Registered module name: **`lez_indexer_module`**. It pairs with the
[`lez-explorer-ui`](https://github.com/logos-co/lez-explorer-ui) block explorer,
which connects to the indexer's RPC endpoint.

### Setup

#### IDE

If you're using an IDE with CMake integration make sure it points to the same cmake directory as the `justfile`, which defaults to `build`.

This will reduce friction when working on the project.

#### Nix

* Use `nix flake update` to bring all nix context and packages
* Use `nix build` to build the package (produces `lez_indexer_module.<dylib|so|dll>`)
* Use `nix run` to launch the module-viewer and check your module loads properly
* Use `nix develop` to setup your IDE

### Running the indexer

The module does **not** start the indexer on load — something must invoke its
`start_indexer` method (via the module-viewer's invoke panel, or another module /
basecamp over the Logos API):

```
start_indexer(config_path, port)
```

* `config_path` — **absolute** path to a JSON config (see
  [`config/indexer_config.json`](config/indexer_config.json)). It must be absolute:
  the module runs inside the `logos_host` subprocess, whose working directory is not
  your shell's.
* `port` — TCP port for the RPC server, e.g. `8779`. Passed as a **string** (see the
  macOS / Qt notes below).

On success it returns `0` and the RPC server listens on `ws://localhost:<port>`;
point the explorer (or any client) there. A non-zero return is the FFI
`OperationStatus` (e.g. `2 = InitializationError`) — note the FFI does not log, so
the numeric code is all you get.

### Configuration

`config/indexer_config.json` is deserialized into the indexer's `IndexerConfig`.
Key fields:

| Field | Meaning |
|---|---|
| `bedrock_config.addr` | L1/bedrock node URL the indexer reads from (default `http://localhost:8080` — it must be reachable). |
| `home` | Directory for the indexer's RocksDB state, **relative to the host's working directory** (`"."` by default). Use an absolute path for a predictable location. |
| `channel_id` | The zone channel the indexer consumes; must match what the sequencer inscribes. |

The config keys must match the `IndexerConfig` schema of the `logos-execution-zone`
rev pinned in `flake.nix`/`flake.lock`; bumping that rev may require re-syncing this
file. Unknown keys are ignored.

### macOS / Qt notes

* **Keep the module name short.** `logos_host` derives a Qt Remote Objects `local:`
  socket from it (`local:logos_<name>_<id>`), and macOS caps Unix socket paths at
  104 bytes. The build emits the library with no `lib` prefix so its filename equals
  the registered name (`lez_indexer_module`) — consumers derive the QtRO invoke
  target from the filename, so the two must stay identical.
* **`Q_INVOKABLE` parameters are `QString`.** The QtRO `ModuleProxy` invokes via
  `QMetaObject::invokeMethod` with exact type matching and delivers arguments as
  `QString`, so `start_indexer` takes the port as a string and parses it internally.