Add reusable rainix-copy-artifacts workflow (no prelude)

.github/workflows/rainix-copy-artifacts.yaml

@@ -0,0 +1,54 @@
+name: rainix-copy-artifacts
+on:
+  workflow_call:
+jobs:
+  copy-artifacts:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: nixbuild/nix-quick-install-action@v30
+        with:
+          nix_conf: |
+            keep-env-derivations = true
+            keep-outputs = true
+      # Substitute prebuilt derivations from the shared Cachix cache so the
+      # toolchain + any prelude build don't refetch crates from crates.io (whose
+      # download endpoint 403s nix's User-Agent). Pushes new paths when
+      # CACHIX_AUTH_TOKEN is set; continue-on-error degrades gracefully.
+      - uses: cachix/cachix-action@v15
+        continue-on-error: true
+        with:
+          name: rainlanguage
+          authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+          # No store-watching daemon: it checkpoints the nix DB concurrently
+          # with cache-nix-action and corrupts it. Push happens in the post step.
+          useDaemon: false
+      - name: Restore and save Nix store
+        uses: nix-community/cache-nix-action@v7
+        with:
+          primary-key: nix-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
+          restore-prefixes-first-match: nix-${{ runner.os }}-
+          gc-max-store-size-linux: 8G
+      - name: Install soldeer dependencies
+        if: hashFiles('soldeer.lock') != ''
+        run: nix develop github:rainlanguage/rainix#sol-shell -c forge soldeer install
+      # No prelude/codegen step on purpose: committing the generated artifacts
+      # (meta, pointers, abi) is exactly what lets consumers build without a
+      # prelude. This job rebuilds from the committed sources and asserts the
+      # committed artifacts still match — it does not regenerate meta inputs.
+      - name: Regenerate pointer artifacts
+        if: hashFiles('script/BuildPointers.sol') != ''
+        run: nix develop github:rainlanguage/rainix#sol-shell -c forge script ./script/BuildPointers.sol
+      - name: Build Solidity
+        run: nix develop github:rainlanguage/rainix#sol-shell -c forge build
+      - name: Copy forge artifacts into committed location
+        if: hashFiles('script/CopyArtifacts.sol') != ''
+        run: nix develop github:rainlanguage/rainix#sol-shell -c forge script ./script/CopyArtifacts.sol --ffi
+      - name: Format (so generated artifacts match committed style)
+        run: nix develop github:rainlanguage/rainix#sol-shell -c forge fmt
+      - name: Assert committed artifacts match freshly built
+        run: |
+          if ! git diff --exit-code; then
+            echo "::error::Committed meta/pointer/abi artifacts are stale. Regenerate (.#prelude, BuildPointers.sol, CopyArtifacts.sol, forge fmt) and commit."
+            exit 1
+          fi