build(nix): reproducible dev + build env via a flake (ADR-0049)

Root flake with two outputs: devShells.default (pinned 1.95.0 toolchain via rust-toolchain.toml + rust-overlay, plus cargo-sweep) and packages.default (rustPlatform.buildRustPackage from the committed Cargo.lock; doCheck=false). flake.lock pins nixpkgs nixos-26.05 / rust-overlay / flake-utils. .envrc (use flake) for direnv parity. Single source of toolchain for dev and the upcoming CI, so they can't drift. Verified through the flake: nix build yields a working binary, clippy clean, 2424 tests pass / 0 fail / 1 intentional ignored doctest. First step toward requirements.md TT5 + D1/D2/D3.
2026-06-12 20:35:39 +00:00
parent 3d4a0fd45e
commit 9189740028
7 changed files with 307 additions and 0 deletions
@@ -0,0 +1,80 @@
+{
+  description = "RDBMS Playground — Rust TUI dev environment + reproducible build";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-26.05";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, rust-overlay, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ (import rust-overlay) ];
+        };
+
+        # Single source of the Rust toolchain: the rustup toolchain file.
+        # rust-overlay provisions the exact channel + components declared there,
+        # so the dev shell and the build package share one pinned toolchain.
+        rust = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
+
+        # Read the package version straight from Cargo.toml so it never drifts
+        # from the crate metadata (no hand-maintained duplicate here).
+        cargoToml = builtins.fromTOML (builtins.readFile ./Cargo.toml);
+
+        # System build inputs are deliberately tiny — this is a pure-Rust TUI:
+        #   * libsqlite3-sys is built with the `bundled` feature, so SQLite is
+        #     compiled from vendored C. That needs a C compiler, which the
+        #     stdenv provides automatically (no entry required here).
+        #   * arboard's clipboard backend is `x11rb` — a pure-Rust socket XCB
+        #     client. It links no C X11 libraries, so none appear below. A live
+        #     X server is only needed at *runtime* to copy; headless sessions
+        #     fall back to OSC 52.
+        # If a future dependency introduces a pkg-config / native-lib link, add
+        # it here (and document why) rather than leaking it into the host env.
+        nativeBuildInputs = [ ];
+        buildInputs = [ ];
+
+        # `nix build` → the release binary, built reproducibly from the pinned
+        # toolchain and the committed Cargo.lock (importCargoLock fetches each
+        # dependency by its lockfile checksum — offline, no cargoHash to churn).
+        # CI's release job consumes this artifact; the gate's tests run
+        # separately via `nix develop -c cargo test` (see below), so the package
+        # build skips the suite — the nix sandbox has no HOME/X server and would
+        # fight the project-dirs / clipboard paths the tests touch.
+        rdbms-playground = pkgs.rustPlatform.buildRustPackage {
+          pname = cargoToml.package.name;
+          version = cargoToml.package.version;
+          src = ./.;
+          cargoLock.lockFile = ./Cargo.lock;
+          inherit nativeBuildInputs buildInputs;
+          doCheck = false;
+        };
+      in {
+        packages.default = rdbms-playground;
+        packages.rdbms-playground = rdbms-playground;
+
+        devShells.default = pkgs.mkShell {
+          inherit buildInputs;
+          nativeBuildInputs = nativeBuildInputs ++ [
+            rust
+            # Dev-disk maintenance: cargo never garbage-collects stale per-hash
+            # build artifacts, so target/ creeps into the tens of GB (see
+            # CLAUDE.md "Build hygiene"). cargo-sweep prunes them; run it
+            # periodically between milestones.
+            pkgs.cargo-sweep
+          ];
+
+          shellHook = ''
+            echo "RDBMS Playground dev shell ($(uname -s))"
+            echo "  rust:  $(rustc --version | cut -d' ' -f1-2)"
+            echo "  cargo: $(cargo --version | cut -d' ' -f1-2)"
+          '';
+        };
+      });
+}