From 4000fc74e4a196893bf38c66479b17f119debe7d Mon Sep 17 00:00:00 2001
From: refcell <abigger87@gmail.com>
Date: Mon, 4 Nov 2024 11:36:35 -0500
Subject: [PATCH 1/2] chore(book): Load a rollup config

---
 book/src/examples/README.md                   |  2 +-
 .../genesis/loading-a-rollup-config.md        |  0
 book/src/examples/load-a-rollup-config.md     | 34 +++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 delete mode 100644 book/src/examples/genesis/loading-a-rollup-config.md
 create mode 100644 book/src/examples/load-a-rollup-config.md

diff --git a/book/src/examples/README.md b/book/src/examples/README.md
index e22c0162..b7da6dd0 100644
--- a/book/src/examples/README.md
+++ b/book/src/examples/README.md
@@ -2,4 +2,4 @@
 
 Examples for working with `op-alloy-*` crates.
 
-TODO: document `op-alloy` crate use and using it with re-exports.
+- [Load a Rollup Config for a Chain ID](./load-a-rollup-config.md)
diff --git a/book/src/examples/genesis/loading-a-rollup-config.md b/book/src/examples/genesis/loading-a-rollup-config.md
deleted file mode 100644
index e69de29b..00000000
diff --git a/book/src/examples/load-a-rollup-config.md b/book/src/examples/load-a-rollup-config.md
new file mode 100644
index 00000000..ec2db0af
--- /dev/null
+++ b/book/src/examples/load-a-rollup-config.md
@@ -0,0 +1,34 @@
+# Loading a Rollup Config from a Chain ID
+
+In this section, the code examples demonstrate loading the
+rollup config for the given L2 Chain ID.
+
+Let's load the Rollup Config for OP Mainnet which hash chain id 10.
+
+```rust
+use op_alloy_genesis::{OP_MAINNET_CONFIG, rollup_config_from_chain_id};
+
+// The chain id for OP Mainnet
+let op_mainnet_id = 10;
+
+// Load a rollup config from the chain id.
+let op_mainnet_config = rollup_config_from_chain_id(op_mainnet_id).expect("infallible");
+
+// The chain id should match the hardcoded chain id.
+assert_eq!(OP_MAINNET_CONFIG, op_mainnet_config);
+```
+
+> ⚠️ Available Configs
+>
+> The `rollup_config_from_chain_id` method in `op-alloy-genesis` uses hardcoded
+> rollup configs. But, there are only a few of these hardcoded rollup configs in
+> `op-alloy-genesis`. This method and these configs are provided for `no_std`
+> environments where dynamic filesystem loading at runtime is not supported
+> in `no_std` environments.
+>
+> In a `std` environment, the [superchain][superchain] crate may be used which
+> dynamically provides all rollup configs from the [superchain-registry][registry]
+> for their respective chain ids.
+
+[superchain]: https://crates.io/crates/superchain
+[registry]: https://github.com/ethereum-optimism/superchain-registry

From 87fffa1efcd7fb915563c9285e98a83e2f72ce6a Mon Sep 17 00:00:00 2001
From: refcell <abigger87@gmail.com>
Date: Mon, 4 Nov 2024 12:04:54 -0500
Subject: [PATCH 2/2] fix(book): missing example link

---
 book/src/SUMMARY.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
index 745e5a51..355c309e 100644
--- a/book/src/SUMMARY.md
+++ b/book/src/SUMMARY.md
@@ -8,6 +8,7 @@
     - [System Config](./building/genesis/system-config.md)
   - [Consensus](./building/consensus.md)
 - [Examples](./examples/README.md)
+  - [Load a Rollup Config](./examples/load-a-rollup-config.md)
 - [Contributing](./CONTRIBUTING.md)
 - [Licensing](./LICENSE.md)
 - [Glossary](./glossary.md)