Fix npm configuration isolation before direct publication

scripts/publish-direct-npm-release.mjs

@@ -194,6 +194,11 @@ export async function publishDirectNpmRelease({
   };
   const report = path.join(root, "direct-release-report.json");
   try {
+    // npm rejects loading one path as both user and global configuration.
+    clean.NPM_CONFIG_USERCONFIG = path.join(cwd, "user.npmrc");
+    clean.NPM_CONFIG_GLOBALCONFIG = path.join(cwd, "global.npmrc");
+    await writeFile(clean.NPM_CONFIG_USERCONFIG, "", { mode: 0o600 });
+    await writeFile(clean.NPM_CONFIG_GLOBALCONFIG, "", { mode: 0o600 });
     const version = execute("npm", ["--version"], {
       cwd,
       environment: clean,

tests/direct-npm-release.test.mjs

@@ -1,3 +1,4 @@
+import { spawnSync } from "node:child_process";
 import assert from "node:assert/strict";
 import test from "node:test";
 import { createHash, generateKeyPairSync, sign } from "node:crypto";
@@ -191,8 +192,8 @@ test("publishes only exact tarballs, dependencies first, from a credential-free
     assert(c.args.includes("--ignore-scripts"));
     assert(c.args.includes("--provenance"));
     assert(c.args.includes("--registry=https://registry.npmjs.org/"));
-    assert.equal(c.opts.environment.NPM_CONFIG_USERCONFIG, "/dev/null");
-    assert.equal(c.opts.environment.NPM_CONFIG_GLOBALCONFIG, "/dev/null");
+    assert.equal(c.opts.environment.NPM_CONFIG_USERCONFIG, path.join(c.opts.cwd, "user.npmrc"));
+    assert.equal(c.opts.environment.NPM_CONFIG_GLOBALCONFIG, path.join(c.opts.cwd, "global.npmrc"));
     assert.notEqual(c.opts.cwd, f.root);
     assert.notEqual(c.opts.cwd, f.dir);
   }
@@ -447,3 +448,21 @@ test("the workflow keeps preparation unprivileged, publication gated and registr
   assert.match(verify, /AGENTPLAT_REGISTRY_CONSUMER_PROFILE: postgres/);
   assert.match(verify, /node-version: 22\.22\.0/);
 });
+
+ test("real npm loads the isolated publication configuration", async (t) => {
+  const f = await fixture(t);
+  await publishDirectNpmRelease({
+    ...f,
+    environment: environment(),
+    fetchImplementation: freshRegistry,
+    execute(command, args, options) {
+      const result = spawnSync(command, ["--version"], {
+        cwd: options.cwd,
+        env: { ...process.env, ...options.environment },
+        encoding: "utf8",
+      });
+      assert.equal(result.status, 0, result.stderr);
+      return result;
+    },
+  });
+});