feat: add local testnet guide

how-to-guides/local-testnet.md

@@ -0,0 +1,143 @@
+# Setting Up a Celestia Local Testnet
+
+This guide walks through setting up a local Celestia testnet with a validator node, bridge node, and light node.
+
+## Prerequisites
+
+- celestia-app installed (based on [compatible versions](./participate.md))
+- celestia node binary installed
+- jq installed
+
+## Starting the Validator Node
+
+First, navigate to the celestia-app scripts directory and run the single node script:
+
+```bash
+cd celestia-app/scripts
+bash single-node.sh
+```
+
+## Setting Up the Bridge Node
+
+Once your validator node is running, get the genesis block hash:
+
+```bash
+curl -X GET "localhost:26657/block?height=1" | jq -r '.result .block_id.hash'
+```
+
+This will return a hash like:
+```
+1D53B32ACB02563E425BA1F8B5178B06A748E0F7B9748A8B1D07C34B454AF595
+```
+
+Set this as an environment variable:
+
+```bash
+export CELESTIA_CUSTOM=test:1D53B32ACB02563E425BA1F8B5178B06A748E0F7B9748A8B1D07C34B454AF595
+```
+
+Initialize the bridge node:
+
+```bash
+celestia bridge init \
+    --node.store $HOME/.celestia-custom-bridge \
+    --core.ip localhost \
+    --core.grpc.port 9090 \
+    --core.rpc.port 26657 \
+    --p2p.network test
+```
+
+Start the bridge node:
+
+```bash
+celestia bridge start \
+    --node.store $HOME/.celestia-custom-bridge \
+    --core.ip localhost \
+    --core.grpc.port 9090 \
+    --core.rpc.port 26657 \
+    --p2p.network test
+```
+
+## Setting Up the Light Node
+
+In a new terminal, set the same environment variable:
+
+```bash
+export CELESTIA_CUSTOM=test:1D53B32ACB02563E425BA1F8B5178B06A748E0F7B9748A8B1D07C34B454AF595
+```
+
+Initialize the light node:
+
+```bash
+celestia light init \
+    --p2p.network test \
+    --core.ip localhost:26657 \
+    --node.store $HOME/.celestia-custom-light/
+```
+
+Get the bridge node's peer info:
+
+```bash
+celestia p2p info --node.store $HOME/.celestia-custom-bridge
+```
+
+From the output, locate the relevant IP4 address and peer ID. The output will look similar to:
+
+```json
+{
+  "result": {
+    "id": "12D3KooWAVsZ36CdczaEXNNnDpsPcVyAnbeBe5EPG7AjttRGfux7",
+    "peer_addr": [
+      "/ip4/10.0.0.125/tcp/2121",
+      "/ip4/10.0.0.125/udp/2121/webrtc-direct/certhash/uEiBXDYwH1McBsLM2aEc3SdvAuhq2ZQ0RUgbjgTvXMQm7LA",
+      "/ip4/71.200.65.106/tcp/16279",
+      "/ip4/71.200.65.106/udp/16279/webrtc-direct/certhash/uEiBXDYwH1McBsLM2aEc3SdvAuhq2ZQ0RUgbjgTvXMQm7LA",
+      "/ip4/127.0.0.1/udp/2121/webrtc-direct/certhash/uEiBXDYwH1McBsLM2aEc3SdvAuhq2ZQ0RUgbjgTvXMQm7LA",
+      "/ip6/::1/tcp/2121",
+      "/ip6/::1/udp/2121/webrtc-direct/certhash/uEiBXDYwH1McBsLM2aEc3SdvAuhq2ZQ0RUgbjgTvXMQm7LA"
+    ]
+  }
+}
+```
+
+Start the light node with custom RPC port and trusted peer:
+
+```bash
+celestia light start \
+    --p2p.network test \
+    --core.ip localhost:26657 \
+    --node.store $HOME/.celestia-custom-light/ \
+    --headers.trusted-peers /ip4/10.0.0.125/udp/2121/webrtc-direct/certhash/uEiBXDYwH1McBsLM2aEc3SdvAuhq2ZQ0RUgbjgTvXMQm7LA/p2p/12D3KooWAVsZ36CdczaEXNNnDpsPcVyAnbeBe5EPG7AjttRGfux7 \
+    --rpc.port 42069
+```
+
+## Funding and Testing
+
+Get the bridge node's account address:
+
+```bash
+celestia state account-address --node.store $HOME/.celestia-custom-bridge
+```
+
+Get the light node's account address:
+
+```bash
+celestia state account-address --node.store $HOME/.celestia-custom-light --url http://localhost:42069
+```
+
+Send funds to the light node:
+
+```bash
+celestia-appd tx bank send validator celestia1p8yx4yveuu6ushyccepsuknaqpqn9ppq07m4n3 10000000utia \
+    --chain-id test \
+    --keyring-backend test \
+    --fees 500utia
+```
+
+Test by submitting a blob from the light node:
+
+```bash
+celestia blob submit 0x4772756763686174 '"Simplicity is the ultimate sophistication." -Leonardo da Vinci' \
+    --node.store $HOME/.celestia-custom-light \
+    --url http://localhost:42069
+```