Check SCSpecType is a superset of SCValType

.github/workflows/scspectype-superset.yml

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+name: SCSpecType Superset
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    runs-on: ubuntu-slim
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: actions/setup-node@v7
+        with:
+          node-version: lts/*
+
+      - run: node .scripts/check-scspectype-superset.ts

.scripts/check-scspectype-superset.ts

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+// Every SCValType that can appear at a contract function boundary must be
+// expressible in a contract spec, so SCSpecType needs a counterpart for it.
+// The names line up by prefix: SCV_U32 -> SC_SPEC_TYPE_U32.
+
+import { readFileSync } from "node:fs";
+
+// SCValType variants that cannot cross a contract function boundary, and so
+// intentionally have no SCSpecType counterpart.
+const EXCLUDED = [
+  "CONTRACT_INSTANCE",
+  "LEDGER_KEY_CONTRACT_INSTANCE",
+  "LEDGER_KEY_NONCE",
+];
+
+const spec = readFileSync("Stellar-contract-spec.x", "utf8");
+const val = readFileSync("Stellar-contract.x", "utf8").match(/\bSCV_\w+/g) ?? [];
+
+const missing = [...new Set(val.map((name) => name.slice("SCV_".length)))]
+  .filter((name) => !EXCLUDED.includes(name))
+  .filter((name) => !new RegExp(`\\bSC_SPEC_TYPE_${name}\\b`).test(spec));
+
+if (missing.length > 0) {
+  console.log(`
+SCValType variants with no SCSpecType counterpart: ${missing.map((n) => "SCV_" + n).join(", ")}
+
+SCSpecType must be a superset of SCValType so that every value type usable at a
+contract function boundary can be captured in a contract spec. Either add the
+missing SCSpecType variant, or, if the value cannot cross a contract boundary,
+add it to EXCLUDED in this script.`);
+  process.exit(1);
+}
+
+console.log("SCSpecType covers every SCValType variant.");