fix: hand npm the release artifact's absolute path, so publishing finds it

The first real 0.2.0 publish failed on its first package with ENOENT:
"Publishing ekklesia-contracts-0.2.0.tgz failed: npm error code ENOENT".

The publish workflow passes a relative release path,
--release "$(find package-train …)", which is
package-train/ekklesia-packages-0.2.0. The tool validated the artifacts
relative to the job's working directory, but ran npm in its own
temporary home (cwd /tmp/ekklesia-publish-XXXXXX) with the same relative
path, package-train/ekklesia-packages-0.2.0/ekklesia-contracts-0.2.0.tgz,
which there names nothing. The disposable-registry suite always passed
an absolute path, so it never saw this.

- loadReleaseTrain resolves the release directory once; every artifact
  path is absolute from validation on, and npm is given only that exact
  file's absolute path (anything else is refused at the npm boundary).
- Just before each upload the file is checked against the validated
  bytes once more; the tool logs the absolute path it publishes, and a
  failure names it with npm's path/syscall lines (npm's temporary home
  masked, the token never shown).
- Regression tests: unit tests with a recording npm (relative nested
  release from another cwd; npm's argv, cwd, and the file's existence; a
  changed artifact refused before npm runs), which fail on the previous
  tool; and a disposable-Gitea test that runs the CLI exactly as the
  workflow does, from the Actions artifact layout, round-tripping all
  nine packages byte for byte.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tests/package-publication.test.ts

@@ -1,4 +1,4 @@
-import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
+import { chmod, cp, mkdir, mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import path from "node:path";
 import { fileURLToPath } from "node:url";
@@ -462,6 +462,119 @@ describe("the registry and its credentials", () => {
   });
 });
 
+describe("the artifact npm is given", () => {
+  /**
+   * The release where the Actions artifact puts it, `<workspace>/package-train/<release>`, named
+   * relatively from the current directory, which is not the release directory: exactly how the
+   * publish workflow called the tool when npm was handed a path relative to its own temporary home.
+   */
+  async function nestedRelease(): Promise<{ relative: string; absolute: string }> {
+    const workspace = await mkdtemp(path.join(tmpdir(), "ekklesia-workspace-"));
+    scratch.push(workspace);
+    const absolute = path.join(workspace, "package-train", `ekklesia-packages-${VERSION}`);
+    await mkdir(path.dirname(absolute), { recursive: true });
+    await cp(await releaseDirectory(), absolute, { recursive: true });
+    const relative = path.relative(process.cwd(), absolute);
+    expect(path.isAbsolute(relative)).toBe(false);
+    expect(process.cwd()).not.toBe(absolute);
+    return { absolute, relative };
+  }
+
+  /** An npm that records what it was given, and where it ran, then fails as a registry would. */
+  async function recordingNpm(): Promise<{
+    npm: string;
+    calls: () => Promise<{ argv: string[]; cwd: string; exists: boolean }[]>;
+  }> {
+    const directory = await mkdtemp(path.join(tmpdir(), "ekklesia-fake-npm-"));
+    scratch.push(directory);
+    const log = path.join(directory, "calls.jsonl");
+    const npm = path.join(directory, "npm");
+    await writeFile(
+      npm,
+      `#!/usr/bin/env node
+const { appendFileSync, existsSync } = require("node:fs");
+const argv = process.argv.slice(2);
+appendFileSync(${JSON.stringify(log)}, JSON.stringify({ argv, cwd: process.cwd(), exists: existsSync(argv[1] ?? "") }) + "\\n");
+process.stderr.write("npm error code E503\\nnpm error 503 Service Unavailable\\n");
+process.exit(1);
+`,
+    );
+    await chmod(npm, 0o755);
+    return {
+      calls: async () =>
+        (await readFile(log, "utf8").catch(() => ""))
+          .split("\n")
+          .filter(Boolean)
+          .map((line) => JSON.parse(line)),
+      npm,
+    };
+  }
+
+  const notFound = (async () => new Response("{}", { status: 404 })) as typeof fetch;
+
+  it("resolves a relative, nested release to absolute artifact paths when it loads the train", async () => {
+    const { absolute, relative } = await nestedRelease();
+    const train = await loadReleaseTrain(relative, { revision: REVISION, version: VERSION });
+    for (const local of train.packages) {
+      expect(local.path).toBe(path.join(absolute, local.entry.file));
+      expect(path.isAbsolute(local.path)).toBe(true);
+      expect((await readFile(local.path)).equals(local.data)).toBe(true);
+    }
+  });
+
+  it("hands npm the exact validated tarball by its absolute path, from npm's own directory, and says which", async () => {
+    const { absolute, relative } = await nestedRelease();
+    const { calls, npm } = await recordingNpm();
+    const error = await publishPackageTrain({
+      fetch: notFound,
+      npm,
+      registry: REGISTRY,
+      releaseDirectory: relative,
+      revision: REVISION,
+      token: "publish-token-value",
+      version: VERSION,
+    }).catch((caught: unknown) => caught);
+    expect(error).toMatchObject({ code: "PUBLISH_FAILED" });
+    const first = tarballName("@ekklesia/contracts", VERSION);
+    const expected = path.join(absolute, first);
+    // The failure names the exact file npm was given, and never the token.
+    expect((error as Error).message).toContain(expected);
+    expect((error as Error).message).toContain("E503");
+    expect((error as Error).message).not.toContain("publish-token-value");
+
+    const [call] = await calls();
+    expect(call?.argv.slice(0, 2)).toEqual(["publish", expected]);
+    expect(call?.exists).toBe(true);
+    // npm ran in a directory of its own, where a relative path would have named nothing.
+    expect(call?.cwd).not.toBe(absolute);
+    expect(path.isAbsolute(call?.cwd ?? "")).toBe(true);
+    expect(JSON.stringify(call)).not.toContain("publish-token-value");
+  });
+
+  it("refuses to publish an artifact that changed after it was validated, before npm runs", async () => {
+    const { absolute, relative } = await nestedRelease();
+    const { calls, npm } = await recordingNpm();
+    const file = path.join(absolute, tarballName("@ekklesia/contracts", VERSION));
+    await expect(
+      publishPackageTrain({
+        fetch: notFound,
+        hooks: {
+          beforePublish: async (_name, index) => {
+            if (index === 0) await writeFile(file, "changed after validation");
+          },
+        },
+        npm,
+        registry: REGISTRY,
+        releaseDirectory: relative,
+        revision: REVISION,
+        token: "publish-token-value",
+        version: VERSION,
+      }),
+    ).rejects.toMatchObject({ code: "INVALID_RELEASE" });
+    expect(await calls()).toEqual([]);
+  });
+});
+
 describe("what the publisher may do to a registry", () => {
   it("never deletes, unpublishes, or overwrites: it only publishes new versions and moves a tag", async () => {
     // Code only: the tool's comments may say what it never does.