A Logos Core **service module** (`type: core`, universal authoring model) that runs the Logos Execution Zone (L2) indexer and exposes it to the Logos ecosystem. It is a thin Qt-free 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 and indexes the zone's channel, and exposes **query methods over the Logos protocol** (Qt Remote Objects).
Registered module name: **`lez_indexer_module`**. Its public methods *are* its API — other modules call them in-process over the Logos protocol. It pairs with the
[`lez-explorer-ui`](https://github.com/logos-co/lez-explorer-ui) block explorer, which reads from it **in-process over the Logos protocol** (typed `modules().lez_indexer_module.*` calls) — no RPC endpoint or socket in between.
> **Keep the module name short.** `logos_host` derives a Qt Remote Objects `local:` socket from it (`local:logos_<name>_<id>`), and Unix socket path names are limited to at most 108 bytes (see [man unix](https://man7.org/linux/man-pages/man7/unix.7.html)). 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.
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 protocol):
-`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.
On success it returns `0`; a non-zero return is the FFI `OperationStatus` (e.g. `2 = InitializationError`). Once started, consume the indexer through the query methods below.
Each returns a compact JSON string (an **empty** string means not-found / failed query); all ids/hashes are 32-byte hex, all numeric args/ids are decimal strings.
| Method | Returns |
| --- | --- |
| `getLastFinalizedBlockId()` | tip block id (bare decimal string) |
| `getBlockById(block_id)` | block JSON |
| `getBlockByHash(hash)` | block JSON |
| `getBlocks(before, limit)` | JSON array of blocks; `before` = `""` for the tip, else a block id to page back from |
| `getTransaction(hash)` | transaction JSON |
| `getAccount(account_id)` | account JSON (the payload omits the id; callers inject the queried id) |
| `getTransactionsByAccount(account_id, offset, limit)` | JSON array of transactions touching the account |
Because the module uses the universal authoring model (`interface: "universal"`), it publishes a typed LIDL contract, so universal consumers get Qt-typed wrappers (`modules().lez_indexer_module.getBlockById(...)`) rather than dynamic by-name calls.
| `bedrock_config.addr` | L1/bedrock node URL the indexer reads from; it must be reachable. | `http://localhost:8080` |
| `home` | Directory for the indexer's RocksDB state, relative to the host's working directory. 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.
