Pin Rust version to 1.85.0

Cargo.toml

@@ -5,6 +5,7 @@ resolver = "3"
 [workspace.package]
 edition = "2024"
 license = "MIT OR Apache-2.0"
+rust-version = "1.85.0"
 
 [workspace.lints.rust]
 unsafe_code = "forbid"

crates/README.md

@@ -3,7 +3,7 @@
 Independent Rust app crates live in this directory.
 
 Each subdirectory should be a normal Cargo package with its own `Cargo.toml`.
-The repository root is a virtual workspace, so shared commands such as `make fmt-check`, `make clippy`, and `make test` run across all crates.
+The repository root is a virtual workspace, so shared commands such as `make format`, `make lint`, and `make test` run across all crates.
 
 Suggested shape:
 

crates/geomerge-demo/Cargo.toml

@@ -3,6 +3,7 @@ name = "geomerge-demo"
 version = "0.1.0"
 edition.workspace = true
 license.workspace = true
+rust-version.workspace = true
 
 [lints]
 workspace = true

flake.nix

@@ -18,8 +18,8 @@
           overlays = [ rust-overlay.overlays.default ];
         };
 
-        # Edition 2024 requires Rust >= 1.85. Pin to a recent stable.
+        # Pinned to match workspace.package.rust-version in Cargo.toml.
-        rustToolchain = pkgs.rust-bin.stable.latest.default.override {
+        rustToolchain = pkgs.rust-bin.stable."1.85.0".default.override {
           extensions = [ "rust-src" "rust-analyzer" "clippy" "rustfmt" ];
         };
       in

rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "1.85.0"
+components = ["rustfmt", "clippy", "rust-analyzer"]