fix: validate sandbox plugin exports and fix plugin packaging (#363)

* fix(webhook-notifier): add build step and export built files

The webhook-notifier plugin exported raw TypeScript source from its
package.json exports (./sandbox pointed to src/sandbox-entry.ts).
When the Vite plugin resolved this at site build time, it embedded
unbuilt TypeScript into the sandbox module, causing "Unexpected token
'{'" errors at runtime.

Add a tsdown build step (matching sandboxed-test's pattern) and update
the exports map to point to dist/*.mjs.

Fixes #150

* fix(core): reject unbuilt source in sandbox module generator and bundle validator

Add two validation checks to prevent plugins with misconfigured exports
from silently breaking site builds:

1. generateSandboxedPluginsModule() now throws a clear error if a
   sandbox entrypoint resolves to a TypeScript/JSX source file instead
   of pre-built JavaScript. This catches the problem at site build time
   with an actionable message.

2. The `emdash bundle` command now validates that all package.json
   exports point to built files (.js/.mjs), not source (.ts/.tsx/.jsx).
   This catches the misconfiguration at plugin publish time, before
   consumers are affected.

Fixes #150

* chore: add changeset for sandbox source validation

* fix: use slash syntax for e18e rule override in oxlintrc

The test file override for e18e/prefer-static-regex used parenthesis
syntax ("e18e(prefer-static-regex)") which is the diagnostic display
format, not the config format. Changed to slash syntax to match the
top-level rule declarations so the override actually takes effect.

* test: add tests for sandbox source validation

Add tests for both validation checks:

- generateSandboxedPluginsModule: verifies it embeds pre-built JS,
  rejects .ts/.tsx/.mts source files, and includes the plugin ID in
  error messages.

- findSourceExports: verifies it flags .ts/.tsx/.mts/.cts/.jsx exports,
  accepts .mjs/.js exports, and handles conditional export maps.

Also extracts findSourceExports() from the inline bundle.ts validation
into bundle-utils.ts so it can be tested without the CLI harness.

* fix(atproto, audit-log): add build step and export built files

Same issue as webhook-notifier — both plugins exported raw TypeScript
source from their package.json sandbox exports. Add tsdown build steps
and update exports to point to dist/*.mjs.

* refactor(smoke): replace sequential per-site astro builds with recursive pnpm build

The build verification section was running `astro build` individually
and sequentially for every demo and template (~12 sites). Replace with
a single `pnpm run --recursive --filter {./demos/*} --filter
{./templates/*} build` which pnpm parallelizes automatically.

packages/core/tests/unit/astro/virtual-modules-sandbox.test.ts

@@ -0,0 +1,113 @@
+import { mkdtemp, rm, writeFile, mkdir } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+
+import type { PluginDescriptor } from "../../../src/astro/integration/runtime.js";
+import { generateSandboxedPluginsModule } from "../../../src/astro/integration/virtual-modules.js";
+
+function descriptor(overrides: Partial<PluginDescriptor> = {}): PluginDescriptor {
+	return {
+		id: "test-plugin",
+		version: "1.0.0",
+		entrypoint: "@test/plugin/sandbox",
+		format: "standard",
+		capabilities: [],
+		allowedHosts: [],
+		storage: {},
+		adminPages: [],
+		adminWidgets: [],
+		...overrides,
+	};
+}
+
+describe("generateSandboxedPluginsModule", () => {
+	let tmpDir: string;
+
+	beforeEach(async () => {
+		tmpDir = await mkdtemp(join(tmpdir(), "emdash-vm-test-"));
+	});
+
+	afterEach(async () => {
+		await rm(tmpDir, { recursive: true, force: true });
+	});
+
+	async function setupFakeProject(exportPath: string, content: string) {
+		// Create a fake project root with package.json
+		await writeFile(join(tmpDir, "package.json"), JSON.stringify({ name: "test-project" }));
+
+		// Create the plugin package inside node_modules
+		const pluginDir = join(tmpDir, "node_modules", "@test", "plugin");
+		await mkdir(pluginDir, { recursive: true });
+
+		// Determine the directory for the export file
+		const fileParts = exportPath.split("/");
+		if (fileParts.length > 1) {
+			const dir = join(pluginDir, ...fileParts.slice(0, -1));
+			await mkdir(dir, { recursive: true });
+		}
+
+		await writeFile(join(pluginDir, exportPath), content);
+		await writeFile(
+			join(pluginDir, "package.json"),
+			JSON.stringify({
+				name: "@test/plugin",
+				exports: { "./sandbox": `./${exportPath}` },
+			}),
+		);
+	}
+
+	it("returns empty module when no plugins configured", () => {
+		const result = generateSandboxedPluginsModule([], tmpDir);
+		expect(result).toContain("export const sandboxedPlugins = []");
+	});
+
+	it("embeds pre-built JavaScript successfully", async () => {
+		await setupFakeProject("dist/sandbox-entry.mjs", "export default { hooks: {} };");
+
+		const result = generateSandboxedPluginsModule(
+			[descriptor({ entrypoint: "@test/plugin/sandbox" })],
+			tmpDir,
+		);
+
+		expect(result).toContain("sandboxedPlugins");
+		expect(result).toContain("test-plugin");
+		expect(result).toContain("export default { hooks: {} };");
+	});
+
+	it("throws for .ts source files", async () => {
+		await setupFakeProject("src/sandbox-entry.ts", "export default {};");
+
+		expect(() =>
+			generateSandboxedPluginsModule([descriptor({ entrypoint: "@test/plugin/sandbox" })], tmpDir),
+		).toThrow(/unbuilt source/);
+	});
+
+	it("throws for .tsx source files", async () => {
+		await setupFakeProject("src/sandbox-entry.tsx", "export default {};");
+
+		expect(() =>
+			generateSandboxedPluginsModule([descriptor({ entrypoint: "@test/plugin/sandbox" })], tmpDir),
+		).toThrow(/unbuilt source/);
+	});
+
+	it("throws for .mts source files", async () => {
+		await setupFakeProject("src/sandbox-entry.mts", "export default {};");
+
+		expect(() =>
+			generateSandboxedPluginsModule([descriptor({ entrypoint: "@test/plugin/sandbox" })], tmpDir),
+		).toThrow(/unbuilt source/);
+	});
+
+	it("includes plugin id in error message", async () => {
+		await setupFakeProject("src/sandbox-entry.ts", "export default {};");
+
+		expect(() =>
+			generateSandboxedPluginsModule(
+				[descriptor({ id: "my-broken-plugin", entrypoint: "@test/plugin/sandbox" })],
+				tmpDir,
+			),
+		).toThrow(/my-broken-plugin/);
+	});
+});

packages/core/tests/unit/cli/bundle-utils.test.ts

@@ -21,6 +21,7 @@ import {
 	resolveSourceEntry,
 	findNodeBuiltinImports,
 	findBuildOutput,
+	findSourceExports,
 } from "../../../src/cli/commands/bundle-utils.js";
 import type { ResolvedPlugin } from "../../../src/plugins/types.js";
 
@@ -298,3 +299,62 @@ describe("findNodeBuiltinImports", () => {
 		expect(findNodeBuiltinImports(code)).toEqual(["fs"]);
 	});
 });
+
+describe("findSourceExports", () => {
+	it("flags .ts exports", () => {
+		const issues = findSourceExports({ ".": "./src/index.ts" });
+		expect(issues).toEqual([{ exportPath: ".", resolvedPath: "./src/index.ts" }]);
+	});
+
+	it("flags .tsx exports", () => {
+		const issues = findSourceExports({ "./admin": "./src/admin.tsx" });
+		expect(issues).toEqual([{ exportPath: "./admin", resolvedPath: "./src/admin.tsx" }]);
+	});
+
+	it("flags .mts exports", () => {
+		const issues = findSourceExports({ ".": "./src/index.mts" });
+		expect(issues).toHaveLength(1);
+	});
+
+	it("flags .cts exports", () => {
+		const issues = findSourceExports({ ".": "./src/index.cts" });
+		expect(issues).toHaveLength(1);
+	});
+
+	it("flags .jsx exports", () => {
+		const issues = findSourceExports({ ".": "./src/index.jsx" });
+		expect(issues).toHaveLength(1);
+	});
+
+	it("accepts .mjs exports", () => {
+		const issues = findSourceExports({ ".": "./dist/index.mjs" });
+		expect(issues).toEqual([]);
+	});
+
+	it("accepts .js exports", () => {
+		const issues = findSourceExports({ ".": "./dist/index.js" });
+		expect(issues).toEqual([]);
+	});
+
+	it("handles conditional exports with import field", () => {
+		const issues = findSourceExports({
+			".": { import: "./src/index.ts", types: "./dist/index.d.mts" },
+		});
+		expect(issues).toEqual([{ exportPath: ".", resolvedPath: "./src/index.ts" }]);
+	});
+
+	it("accepts conditional exports pointing to built files", () => {
+		const issues = findSourceExports({
+			".": { import: "./dist/index.mjs", types: "./dist/index.d.mts" },
+		});
+		expect(issues).toEqual([]);
+	});
+
+	it("flags multiple bad exports", () => {
+		const issues = findSourceExports({
+			".": "./src/index.ts",
+			"./sandbox": "./src/sandbox-entry.ts",
+		});
+		expect(issues).toHaveLength(2);
+	});
+});