updates

scripts/validate.py

@@ -58,12 +58,15 @@ def main():
 
         snapshot()
         flake = f"path:{source}"
-        nix = ["nix", "--quiet"]
+        nix = ["nix", "--quiet", "--accept-flake-config"]
         locked = ["--no-update-lock-file"]
         # The repository currently exposes only x86_64-linux outputs.
         nix_files = [str(ROOT / name) for name in files if name.endswith(".nix")]
         run("format", nix + ["run", *locked, f"{flake}#formatter.x86_64-linux", "--", *nix_files])
         snapshot()
+        # Upstream devenv evaluates generated Nix (including cabal2nix). Realize
+        # those evaluation dependencies before flake check enters read-only mode.
+        run("prepare-devenv", nix + ["eval", *locked, "--raw", f"{flake}#packages.x86_64-linux.devenv.drvPath"])
         run("check", nix + ["flake", "check", "--no-build", *locked, flake])
         hosts_file = run_dir / "hosts.json"
         # Keep machine-readable output separate from Nix diagnostics.
@@ -90,5 +93,7 @@ def main():
 if __name__ == "__main__":
     try:
         main()
+    except KeyboardInterrupt:
+        sys.exit("Validation interrupted; completed stages do not establish a full pass.")
     except (OSError, ValueError, RuntimeError, subprocess.CalledProcessError) as error:
         sys.exit(str(error))