chore: import upstream snapshot with attribution

.github/scripts/attach-plugin-tarballs.mjs

@@ -0,0 +1,122 @@
+// Attach sandboxed-plugin tarballs to the GitHub releases that
+// `changesets/action` creates during a release run.
+//
+// The decentralized plugin registry (RFC 0001) stores only a *link* to the
+// plugin bytes, not the bytes themselves. By bundling each published
+// sandboxed plugin and uploading the tarball as a release asset, every
+// version automatically gets a stable public URL that an `emdash-plugin
+// publish --url ...` step (or a human) can point a registry record at.
+//
+// Input: the `publishedPackages` output from changesets/action, passed via
+// the PUBLISHED_PACKAGES env var as a JSON array of `{ name, version }`.
+// Only packages under `packages/plugins/*` that expose a `./sandbox` export
+// and are not private are processed; everything else (native plugins, test
+// fixtures) is skipped.
+//
+// Set DRY_RUN=1 to bundle and resolve tarballs without calling `gh`.
+
+import { execFileSync } from "node:child_process";
+import { existsSync, readdirSync, readFileSync } from "node:fs";
+import { join } from "node:path";
+
+const PLUGINS_DIR = "packages/plugins";
+const BUNDLER = "packages/plugin-cli/dist/index.mjs";
+
+const SLASH_RE = /\//g;
+const LEADING_AT_RE = /^@/;
+
+const repo = process.env.GITHUB_REPOSITORY;
+const dryRun = process.env.DRY_RUN === "1";
+
+if (!dryRun && !repo) {
+	console.error("GITHUB_REPOSITORY is not set; cannot target `gh release upload`.");
+	process.exit(1);
+}
+
+// `?? "[]"` only catches undefined/null. An unset Actions output arrives as
+// an empty string, which would make JSON.parse throw, so coalesce that too.
+const raw = process.env.PUBLISHED_PACKAGES?.trim() || "[]";
+let published;
+try {
+	published = JSON.parse(raw);
+} catch (error) {
+	console.error(`Could not parse PUBLISHED_PACKAGES as JSON: ${error.message}`);
+	process.exit(1);
+}
+
+if (!Array.isArray(published) || published.length === 0) {
+	console.log("No published packages to process.");
+	process.exit(0);
+}
+
+// name -> version for the packages that were just published.
+const publishedVersions = new Map(published.map((p) => [p.name, p.version]));
+
+/** Slugify a manifest id the same way the bundler names its tarball. */
+const slugify = (id) => id.replace(SLASH_RE, "-").replace(LEADING_AT_RE, "");
+
+const failures = [];
+let attached = 0;
+
+for (const entry of readdirSync(PLUGINS_DIR, { withFileTypes: true })) {
+	if (!entry.isDirectory()) continue;
+
+	const dir = join(PLUGINS_DIR, entry.name);
+	const pkgPath = join(dir, "package.json");
+	if (!existsSync(pkgPath)) continue;
+
+	// We read every plugin dir, so a single malformed package.json must not
+	// abort the whole step. Treat an unreadable manifest as a skip.
+	let pkg;
+	try {
+		pkg = JSON.parse(readFileSync(pkgPath, "utf-8"));
+	} catch {
+		console.warn(`Skipping ${entry.name}: could not read/parse package.json`);
+		continue;
+	}
+
+	// Only published, public, sandboxed plugins.
+	if (!publishedVersions.has(pkg.name)) continue;
+	if (pkg.private === true) continue;
+	if (!pkg.exports?.["./sandbox"]) {
+		console.log(`Skipping ${pkg.name}: no ./sandbox export (not a sandboxed plugin).`);
+		continue;
+	}
+
+	const version = publishedVersions.get(pkg.name);
+	const tag = `${pkg.name}@${version}`;
+	console.log(`\n=== ${pkg.name}@${version} ===`);
+
+	try {
+		// Bundle. This rebuilds from source and writes dist/<slug>-<version>.tar.gz
+		// plus dist/manifest.json, so we can read the exact id/version back out
+		// rather than guessing the filename (stale tarballs may linger in dist/).
+		execFileSync("node", [BUNDLER, "bundle", "--dir", dir], { stdio: "inherit" });
+
+		const manifest = JSON.parse(readFileSync(join(dir, "dist", "manifest.json"), "utf-8"));
+		const tarball = join(dir, "dist", `${slugify(manifest.id)}-${manifest.version}.tar.gz`);
+		if (!existsSync(tarball)) {
+			throw new Error(`Expected tarball not found: ${tarball}`);
+		}
+
+		if (dryRun) {
+			console.log(`[dry-run] would upload ${tarball} to release ${tag}`);
+		} else {
+			// --clobber so re-runs replace the asset instead of failing.
+			execFileSync("gh", ["release", "upload", tag, tarball, "--clobber", "--repo", repo], {
+				stdio: "inherit",
+			});
+			console.log(`Attached ${tarball} to ${tag}`);
+		}
+		attached++;
+	} catch (error) {
+		console.error(`Failed to attach tarball for ${pkg.name}: ${error.message}`);
+		failures.push(pkg.name);
+	}
+}
+
+console.log(`\nAttached ${attached} plugin tarball(s).`);
+if (failures.length > 0) {
+	console.error(`Failed: ${failures.join(", ")}`);
+	process.exit(1);
+}