fix(dev_server): keep workspace members out of the SSR dep optimizer (#370)

Vite applies the top-level optimizeDeps to the client environment only, so
the ssr environment and worker environments still pre-bundled workspace
members and plugin transforms never ran on them. The member-sources plugin
now adds the member exclude list to every non-client environment through
configEnvironment, which merges with a consumer's own list.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: mikn

changelog.d/dev-server-ssr-optimize-exclude.md

@@ -0,0 +1,11 @@
+### Fixed
+
+- **`ts_dev_server` keeps workspace members out of every environment's dep
+  optimizer.** The generated config listed members only in the top-level
+  `optimizeDeps.exclude`, which Vite applies to the client environment alone.
+  When a framework or worker plugin turned on dep discovery for the `ssr` or a
+  worker environment, that environment pre-bundled a member, and a pre-bundle
+  never reaches plugin transforms such as StyleX. A `configEnvironment` hook
+  now adds the same exclude list to every non-client environment; a
+  consumer's own exclude list still merges in. A member a plugin lists in an
+  environment's `optimizeDeps.include` is still pre-bundled there.

tests/dev_server/dev_server_behaviour_test.go

@@ -385,6 +385,27 @@ func TestDevServerBehaviour(t *testing.T) {
 				t.Errorf("no module id the plugin transformed lies under the member's store %s: %v", store, seen.Transformed)
 			}
 		})
+		t.Run("server_environment_optimizer_cannot_pre_bundle_a_workspace_member", func(t *testing.T) {
+			const pkg = "tests/npm/dev_inherited_types"
+			t.Setenv("MEMBER_SOURCES_SERVER_OPTIMIZERS", "1")
+			ws := t.TempDir()
+			app := filepath.Join(ws, filepath.FromSlash(pkg))
+			mkdir(t, app)
+			mkdir(t, filepath.Join(ws, "bazel-bin"))
+			source := filepath.Join(ws, "packages", "shared", "src")
+			mkdir(t, source)
+			write(t, filepath.Join(source, "index.ts"), `export const tagline: string = "MEMBER_SOURCE";`)
+			write(t, filepath.Join(app, "index.html"), "SERVER_OPTIMIZERS")
+			write(t, filepath.Join(app, "entry.ts"), `export { tagline } from "shared";`)
+			srv := start(t, tree.File(pkg+"/member_sources_vite_dev_launcher").Abs(), ws, t.TempDir())
+			base := srv.awaitHTTP(t, "/index.html")
+			for _, environment := range []string{"ssr", "worker"} {
+				r := get(t, base, "/environment-transform?"+url.Values{"environment": {environment}, "url": {"/entry.ts"}}.Encode())
+				if r.status != 200 || !strings.Contains(r.body, "/packages/shared/src/index.ts") {
+					t.Errorf("the %s environment imports the member from somewhere other than its source: HTTP %d\n%s\n%s", environment, r.status, r.body, srv.log(t))
+				}
+			}
+		})
 		t.Run("workspace_member_is_served_from_its_source", func(t *testing.T) {
 			const pkg = "tests/npm/dev_inherited_types"
 			for _, launcher := range []string{"member_sources_vite_dev_launcher", "member_sources_dev_launcher"} {

tests/npm/dev_inherited_types/member_sources.vite.mjs

@@ -7,6 +7,13 @@ const transformed = [];
 export default {
   plugins: [{
     name: 'member-sources',
+    // Server environments that discover deps to pre-bundle, as worker and SSR framework plugins configure them.
+    config: () => process.env.MEMBER_SOURCES_SERVER_OPTIMIZERS && {
+      environments: {
+        ssr: { optimizeDeps: { noDiscovery: false } },
+        worker: { consumer: 'server', resolve: { noExternal: true }, optimizeDeps: { noDiscovery: false } },
+      },
+    },
     async transform(code, id) {
       transformed.push(id);
       // Like most transforms, it leaves node_modules alone; one that resolves for
@@ -22,6 +29,15 @@ export default {
         sources: JSON.parse(process.env.BAZEL_MEMBER_SOURCES ?? 'null'),
         transformed,
       })));
+      server.middlewares.use('/environment-transform', async (req, res) => {
+        const query = new URL(req.url, 'http://localhost').searchParams;
+        try {
+          res.end((await server.environments[query.get('environment')].transformRequest(query.get('url')))?.code ?? '');
+        } catch (error) {
+          res.statusCode = 500;
+          res.end(String(error?.stack ?? error));
+        }
+      });
     },
   }, {
     name: 'pre-claims',

ts/private/ts_dev_server.bzl

@@ -471,6 +471,8 @@ def _generate_dev_config(
             "const bazelMemberSources = {\n" +
             "  name: 'bazel:member-sources',\n" +
             "  enforce: 'pre',\n" +
+            "  // Vite gives the top-level optimizeDeps to the client environment only; a pre-bundle skips plugin transforms.\n" +
+            "  configEnvironment: name => (name === 'client' ? null : { optimizeDeps: { exclude: [...memberNames] } }),\n" +
             "  async resolveId(id, importer, options) {\n" +
             "    // Only a member by name, or an import from a member's files, can reach a member's store.\n" +
             "    const pkg = id.split('?')[0].split('/').slice(0, id.startsWith('@') ? 2 : 1).join('/');\n" +