diff --git a/TODO.md b/TODO.md
index b3b23a3e6..93b70e618 100644
--- a/TODO.md
+++ b/TODO.md
@@ -12,8 +12,8 @@ When a given step is completed, check it off.
 
 ### Development Environment
 - [x] Create `flake.nix` with Node.js and pnpm
-- [ ] Add Rust toolchain to `flake.nix` (for later WASM work)
-- [ ] Add `flake.lock` and verify `nix develop` works
+- [x] Add Rust toolchain to `flake.nix` (for later WASM work)
+- [x] Add `flake.lock` and verify `nix develop` works
 - [ ] Create `justfile` with `dev`, `build`, `test`, `lint` recipes
 - [ ] Add `just fmt` recipe for code formatting
 - [ ] Add `just wasm` recipe placeholder for Rust builds
diff --git a/flake.nix b/flake.nix
index 2427a3acf..2cf9e6339 100644
--- a/flake.nix
+++ b/flake.nix
@@ -24,6 +24,13 @@
             nodejs_22
             pnpm
 
+            # Rust toolchain for WASM
+            cargo
+            rustc
+            wasm-pack
+            wasm-bindgen-cli
+            rust-analyzer
+
             # Useful development tools
             just
           ];
@@ -32,6 +39,9 @@
             echo "Developer Environment"
             echo "Node.js: $(node --version)"
             echo "pnpm: $(pnpm --version)"
+            echo "Rust: $(rustc --version)"
+            echo "Cargo: $(cargo --version)"
+            echo "wasm-pack: $(wasm-pack --version)"
           '';
         };
       }