refactor(data): memoize loader promise instead of manual deferred

Store the promise of the extracted loadData() directly in the
per-id map rather than resolving a hand-made pending promise at the
end of the load hook. This also propagates loader errors to the
other build's pending consumer, which previously awaited forever.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/node/plugins/staticDataPlugin.ts

@@ -58,15 +58,46 @@ export const staticDataPlugin: Plugin = {
 
   load: {
     filter: { id: loaderMatch },
-    async handler(id) {
+    handler(id) {
-      let _resolve: ((res: any) => void) | undefined
+      if (isBuild) return (idToPendingPromiseMap[id] ??= loadData(id))
-      if (isBuild) {
+      return loadData(id)
-        if (idToPendingPromiseMap[id]) return idToPendingPromiseMap[id]
+    }
-        idToPendingPromiseMap[id] = new Promise((r) => {
+  },
-          _resolve = r
+
-        })
+  hotUpdate({ file, modules: existingMods }) {
+    if (this.environment.name !== 'client') return
+
+    const modules: EnvironmentModuleNode[] = []
+    const normalizedFile = normalizePath(file)
+
+    // Trigger update if a dependency (including transitive ones) changed.
+    if (normalizedFile in depToLoaderModuleIdsMap) {
+      for (const id of Array.from(
+        depToLoaderModuleIdsMap[normalizedFile] || []
+      )) {
+        delete idToLoaderModulesMap[id]
+        const mod = this.environment.moduleGraph.getModuleById(id)
+        if (mod) modules.push(mod)
+      }
+    }
+
+    // Also check if the file matches any custom watch patterns.
+    for (const id in idToLoaderModulesMap) {
+      const loader = idToLoaderModulesMap[id]
+      if (
+        loader?.watch?.length &&
+        pm(loader.watch, loader.options.globOptions)(normalizedFile)
+      ) {
+        const mod = this.environment.moduleGraph.getModuleById(id)
+        if (mod) modules.push(mod)
+      }
+    }
+
+    return modules.length ? [...existingMods, ...modules] : undefined
+  }
 }
 
+async function loadData(id: string): Promise<string> {
   const base = path.dirname(id)
   let watch: LoaderModule['watch']
   let load: LoaderModule['load']
@@ -107,42 +138,5 @@ export const staticDataPlugin: Plugin = {
   // record loader module for HMR
   if (server) idToLoaderModulesMap[id] = { watch, load, options }
 
-      const result = `export const data = JSON.parse(${JSON.stringify(JSON.stringify(data))})`
+  return `export const data = JSON.parse(${JSON.stringify(JSON.stringify(data))})`
-
-      if (_resolve) _resolve(result)
-      return result
-    }
-  },
-
-  hotUpdate({ file, modules: existingMods }) {
-    if (this.environment.name !== 'client') return
-
-    const modules: EnvironmentModuleNode[] = []
-    const normalizedFile = normalizePath(file)
-
-    // Trigger update if a dependency (including transitive ones) changed.
-    if (normalizedFile in depToLoaderModuleIdsMap) {
-      for (const id of Array.from(
-        depToLoaderModuleIdsMap[normalizedFile] || []
-      )) {
-        delete idToLoaderModulesMap[id]
-        const mod = this.environment.moduleGraph.getModuleById(id)
-        if (mod) modules.push(mod)
-      }
-    }
-
-    // Also check if the file matches any custom watch patterns.
-    for (const id in idToLoaderModulesMap) {
-      const loader = idToLoaderModulesMap[id]
-      if (
-        loader?.watch?.length &&
-        pm(loader.watch, loader.options.globOptions)(normalizedFile)
-      ) {
-        const mod = this.environment.moduleGraph.getModuleById(id)
-        if (mod) modules.push(mod)
-      }
-    }
-
-    return modules.length ? [...existingMods, ...modules] : undefined
-  }
 }