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bridges/snowbridge/README.md

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+# Snowbridge ·
+[![codecov](https://codecov.io/gh/Snowfork/snowbridge/branch/main/graph/badge.svg?token=9hvgSws4rN)]
+(https://codecov.io/gh/Snowfork/snowbridge)
+![GitHub](https://img.shields.io/github/license/Snowfork/snowbridge)
+
+Snowbridge is a trustless bridge between Polkadot and Ethereum. For documentation, visit https://docs.snowbridge.network.
+
+## Components
+
+### Parachain
+
+Polkadot parachain and our pallets. See [parachain/README.md](https://github.com/Snowfork/snowbridge/blob/main/parachain/README.md).
+
+### Contracts
+
+Ethereum contracts and unit tests. See [contracts/README.md](https://github.com/Snowfork/snowbridge/blob/main/contracts/README.md)
+
+### Relayer
+
+Off-chain relayer services for relaying messages between Polkadot and Ethereum. See
+[relayer/README.md](https://github.com/Snowfork/snowbridge/blob/main/relayer/README.md)
+
+### Local Testnet
+
+Scripts to provision a local testnet, running the above services to bridge between local deployments of Polkadot and
+Ethereum. See [web/packages/test/README.md](https://github.com/Snowfork/snowbridge/blob/main/web/packages/test/README.md).
+
+### Smoke Tests
+
+Integration tests for our local testnet. See [smoketest/README.md](https://github.com/Snowfork/snowbridge/blob/main/smoketest/README.md).
+
+## Development
+
+We use the Nix package manager to provide a reproducible and maintainable developer environment.
+
+After [installing nix](https://nixos.org/download.html) Nix, enable [flakes](https://nixos.wiki/wiki/Flakes):
+
+```sh
+mkdir -p ~/.config/nix
+echo 'experimental-features = nix-command flakes' >> ~/.config/nix/nix.conf
+```
+
+Then activate a developer shell in the root of our repo, where
+[`flake.nix`](https://github.com/Snowfork/snowbridge/blob/main/flake.nix) is located:
+
+```sh
+nix develop
+```
+
+Also make sure to run this initialization script once:
+```sh
+scripts/init.sh
+```
+
+### Support for code editors
+
+To ensure your code editor (such as VS Code) can execute tools in the nix shell, startup your editor within the
+interactive shell.
+
+Example for VS Code:
+
+```sh
+nix develop
+code .
+```
+
+### Custom shells
+
+The developer shell is bash by default. To preserve your existing shell:
+
+```sh
+nix develop --command $SHELL
+```
+
+### Automatic developer shells
+
+To automatically enter the developer shell whenever you open the project, install
+[`direnv`](https://direnv.net/docs/installation.html) and use the template `.envrc`:
+
+```sh
+cp .envrc.example .envrc
+direnv allow
+```
+
+### Upgrading the Rust toolchain
+
+Sometimes we would like to upgrade rust toolchain. First update `parachain/rust-toolchain.toml` as required and then
+update `flake.lock` running
+```sh
+nix flake lock --update-input rust-overlay
+```
+
+## Troubleshooting
+
+Check the contents of all `.envrc` files.
+
+Remove untracked files:
+```sh
+git clean -idx
+```
+
+Ensure that the current Rust toolchain is the one selected in `scripts/init.sh`.
+
+Ensure submodules are up-to-date:
+```sh
+git submodule update
+```
+
+Check untracked files & directories:
+```sh
+git clean -ndx | awk '{print $3}'
+```
+After removing `node_modules` directories (eg. with `git clean above`), clear the pnpm cache:
+```sh
+pnpm store prune
+```
+
+Check Nix config in `~/.config/nix/nix.conf`.
+
+Run a pure developer shell (note that this removes access to your local tools):
+```sh
+nix develop -i --pure-eval
+```
+
+## Security
+
+The security policy and procedures can be found in SECURITY.md.