fix(bundler): set is_export_star_target in dev server mode (#27521)

In dev server mode, patchImportRecordSourceIndices intentionally skips
saving source_index on JS import records. This caused the
is_export_star_target flag to never be set on export-star targets,
because the flag-setting code relied on source_index being valid.

Without this flag, the barrel optimizer could incorrectly defer
submodules of packages that are targets of `export *` from another
barrel (e.g., @tanstack/query-core being star-exported from
@tanstack/react-query), leading to classes like QueryClient becoming
undefined and causing "Right-hand side of 'instanceof' is not an
object" errors.

Fix: fall back to resolving the source index via pathToSourceIndexMap
when source_index is not set, matching the same pattern used elsewhere
in the barrel optimization code.

Co-Authored-By: Claude <noreply@anthropic.com>

src/bundler/bundle_v2.zig

@@ -4209,13 +4209,18 @@ pub const BundleV2 = struct {
                 });
                 result.ast.import_records = import_records;
 
-                // Set is_export_star_target for barrel optimization
+                // Set is_export_star_target for barrel optimization.
+                // In dev server mode, source_index is not saved on JS import
+                // records, so fall back to resolving via the path map.
+                const path_to_source_index_map = this.pathToSourceIndexMap(result.ast.target);
                 for (result.ast.export_star_import_records) |star_record_idx| {
                     if (star_record_idx < import_records.len) {
                         const star_ir = import_records.slice()[star_record_idx];
-                        if (star_ir.source_index.isValid()) {
-                            graph.input_files.items(.flags)[star_ir.source_index.get()].is_export_star_target = true;
-                        }
+                        const resolved_index = if (star_ir.source_index.isValid())
+                            star_ir.source_index.get()
+                        else
+                            path_to_source_index_map.getPath(&star_ir.path) orelse continue;
+                        graph.input_files.items(.flags)[resolved_index].is_export_star_target = true;
                     }
                 }
 

test/bake/dev/bundle.test.ts

@@ -550,6 +550,69 @@ devTest("barrel optimization: multi-file imports preserved across rebuilds", {
   },
 });
 
+devTest("barrel optimization: export star target not deferred (#27521)", {
+  files: {
+    "index.html": emptyHtmlFile({ scripts: ["index.ts"] }),
+    // The user imports from consumer-lib, which is a non-barrel package
+    // that imports QueryClient from outer-lib.
+    "index.ts": `
+      import { useQuery } from 'consumer-lib';
+      console.log('result: ' + useQuery());
+    `,
+    // consumer-lib is NOT a barrel — it has real code that uses
+    // QueryClient from outer-lib. This mirrors @refinedev/core
+    // importing QueryClient from @tanstack/react-query.
+    "node_modules/consumer-lib/package.json": JSON.stringify({
+      name: "consumer-lib",
+      version: "1.0.0",
+      main: "./index.js",
+    }),
+    "node_modules/consumer-lib/index.js": `
+      import { QueryClient } from 'outer-lib';
+      export function useQuery() {
+        const client = new QueryClient();
+        return client instanceof QueryClient ? 'PASS' : 'FAIL';
+      }
+    `,
+    // outer-lib is a barrel with sideEffects:false that re-exports
+    // everything from inner-lib via export *. Mirrors @tanstack/react-query.
+    "node_modules/outer-lib/package.json": JSON.stringify({
+      name: "outer-lib",
+      version: "1.0.0",
+      main: "./index.js",
+      sideEffects: false,
+    }),
+    "node_modules/outer-lib/index.js": `
+      export * from 'inner-lib';
+      export { Unrelated } from './unrelated.js';
+    `,
+    "node_modules/outer-lib/unrelated.js": `export const Unrelated = "X";`,
+    // inner-lib is a barrel with sideEffects:false that re-exports
+    // from submodules. Mirrors @tanstack/query-core. Without the fix,
+    // the barrel optimizer defers queryClient.js because it doesn't
+    // know inner-lib is an export-star target (source_index is not
+    // set in dev-server mode), so QueryClient becomes undefined.
+    "node_modules/inner-lib/package.json": JSON.stringify({
+      name: "inner-lib",
+      version: "1.0.0",
+      main: "./index.js",
+      sideEffects: false,
+    }),
+    "node_modules/inner-lib/index.js": `
+      export { QueryClient } from './queryClient.js';
+      export { Other } from './other.js';
+    `,
+    "node_modules/inner-lib/queryClient.js": `
+      export class QueryClient { constructor() { this.ready = true; } }
+    `,
+    "node_modules/inner-lib/other.js": `export const Other = "OTHER";`,
+  },
+  async test(dev) {
+    await using c = await dev.client("/");
+    await c.expectMessage("result: PASS");
+  },
+});
+
 devTest("barrel optimization: two export-from blocks pointing to the same source", {
   files: {
     "index.html": emptyHtmlFile({ scripts: ["index.ts"] }),