feat: validate runtime configuration before mount

src/contracts/env.js

@@ -0,0 +1,54 @@
+const forbiddenConfigName = /(SECRET|PASSWORD|PRIVATE_KEY|TOKEN)/i;
+
+export const ENV_REGISTRY = Object.freeze({
+  VITE_BUILD_ID: build("public-metadata", true, null),
+  VITE_COMMIT_SHA: build("public-metadata", false, "local"),
+  VITE_ROUTER_BASE_PATH: build("compile-time", true, "/"),
+  VITE_RUNTIME_CONFIG_URL: build("compile-time", true, "/config.json"),
+  APP_ENV: runtime("public", true, null),
+  API_BASE_URL: runtime("public-sensitive", true, null),
+  REQUEST_TIMEOUT_MS: runtime("public", false, 10_000),
+  MAX_RETRY_ATTEMPTS: runtime("public", false, 2),
+  TELEMETRY_ENABLED: runtime("public", true, false),
+  TELEMETRY_ENDPOINT: runtime("public-sensitive", false, null),
+  AUTH_MODE: runtime("public", true, "external"),
+  CONFIG_SCHEMA_VERSION: runtime("public", true, null),
+  API_CONTRACT_VERSION: runtime("public", true, null),
+  RELEASE_MANIFEST_URL: runtime("public", true, "/release-manifest.json"),
+});
+
+/**
+ * @param {string} classification
+ * @param {boolean} required
+ * @param {unknown} defaultValue
+ */
+function build(classification, required, defaultValue) {
+  return Object.freeze({ phase: "build", classification, required, defaultValue });
+}
+
+/**
+ * @param {string} classification
+ * @param {boolean} required
+ * @param {unknown} defaultValue
+ */
+function runtime(classification, required, defaultValue) {
+  return Object.freeze({ phase: "runtime", classification, required, defaultValue });
+}
+
+/** @param {Record<string, unknown>} config */
+export function assertSafeConfigNames(config) {
+  for (const name of Object.keys(config)) {
+    if (forbiddenConfigName.test(name)) {
+      throw new Error(`Forbidden client configuration key: ${name}`);
+    }
+  }
+}
+
+export function getBuildConfig(environment = import.meta.env) {
+  const buildId = environment.VITE_BUILD_ID || "local-build";
+  const commitSha = environment.VITE_COMMIT_SHA || "local";
+  const routerBasePath = environment.VITE_ROUTER_BASE_PATH || "/";
+  const runtimeConfigUrl = environment.VITE_RUNTIME_CONFIG_URL || "/config.json";
+
+  return Object.freeze({ buildId, commitSha, routerBasePath, runtimeConfigUrl });
+}