Emdash source with visual editor image upload fix

Fixes:
1. media.ts: wrap placeholder generation in try-catch
2. toolbar.ts: check r.ok, display error message in popover

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/);
+	});
+});