fix: error bundling JSR islands (#2552)

deno.json

@@ -37,6 +37,7 @@
     "@astral/astral": "jsr:@astral/astral@^0.4.0",
     "@fresh/plugin-tailwind": "./plugin-tailwindcss/src/mod.ts",
     "@luca/esbuild-deno-loader": "jsr:@luca/esbuild-deno-loader@^0.10.3",
+    "@marvinh-test/fresh-island": "jsr:@marvinh-test/fresh-island@^0.0.1",
     "@preact/signals": "npm:@preact/signals@^1.2.3",
     "@std/async": "jsr:@std/async@^0.224.1",
     "@std/cli": "jsr:@std/cli@^0.224.5",

src/dev/builder_test.ts

@@ -2,6 +2,7 @@ import { expect } from "@std/expect";
 import * as path from "@std/path";
 import { Builder } from "./builder.ts";
 import { App } from "../app.ts";
+import { RemoteIsland } from "@marvinh-test/fresh-island";
 
 Deno.test({
   name: "Builder - chain onTransformStaticFile",
@@ -64,3 +65,26 @@ Deno.test({
     expect(css).toContain('body { background: url("/foo.jpg?__frsh_c=');
   },
 });
+
+Deno.test({
+  name: "Builder - can bundle islands from JSR",
+  fn: async () => {
+    const builder = new Builder();
+    const tmp = await Deno.makeTempDir();
+    const app = new App({
+      staticDir: tmp,
+      build: {
+        outDir: path.join(tmp, "dist"),
+      },
+    });
+
+    app.island("jsr:@marvinh-test/fresh-island", "RemoteIsland", RemoteIsland);
+
+    await builder.build(app);
+
+    const code = await Deno.readTextFile(
+      path.join(tmp, "dist", "static", "RemoteIsland.js"),
+    );
+    expect(code).toContain('"remote-island"');
+  },
+});

src/dev/esbuild.ts

@@ -110,7 +110,19 @@ export async function bundleJs(
       dependencies.set(entryPath, imports);
 
       if (entryPath !== "fresh-runtime.js" && entry.entryPoint !== undefined) {
-        const filePath = path.join(options.cwd, entry.entryPoint);
+        let filePath = "";
+        // Resolve back specifiers to original url. This is necessary
+        // to get JSR dependencies to match what we specified as
+        // an entry point to esbuild.
+        if (
+          entry.entryPoint.startsWith("https://") ||
+          entry.entryPoint.startsWith("http://")
+        ) {
+          const basename = path.basename(entryPath, path.extname(entryPath));
+          filePath = options.entryPoints[basename];
+        } else {
+          filePath = path.join(options.cwd, entry.entryPoint);
+        }
 
         const name = entryToName.get(filePath)!;
         entryToChunk.set(name, entryPath);