fix: properly track re-exports of server function factories

fixes #6029

Author: schiller-manuel

e2e/react-start/server-functions/src/routes/factory/-functions/functions.ts

@@ -2,6 +2,10 @@ import { createMiddleware, createServerFn } from '@tanstack/react-start'
 import { createBarServerFn } from './createBarServerFn'
 import { createFooServerFn } from './createFooServerFn'
 import { createFakeFn } from './createFakeFn'
+// Test re-export syntax: `export { foo } from './module'`
+import { reexportFactory } from './reexportIndex'
+// Test star re-export syntax: `export * from './module'`
+import { starReexportFactory } from './starReexportIndex'
 
 export const fooFn = createFooServerFn().handler(({ context }) => {
   return {
@@ -91,3 +95,23 @@ export const composedFn = composeFactory()
       context,
     }
   })
+
+// Test that re-exported factories (using `export { foo } from './module'`) work correctly
+// The middleware from reexportFactory should execute and add { reexport: 'reexport-middleware-executed' } to context
+export const reexportedFactoryFn = reexportFactory().handler(({ context }) => {
+  return {
+    name: 'reexportedFactoryFn',
+    context,
+  }
+})
+
+// Test that star re-exported factories (using `export * from './module'`) work correctly
+// The middleware from starReexportFactory should execute and add { starReexport: 'star-reexport-middleware-executed' } to context
+export const starReexportedFactoryFn = starReexportFactory().handler(
+  ({ context }) => {
+    return {
+      name: 'starReexportedFactoryFn',
+      context,
+    }
+  },
+)

e2e/react-start/server-functions/src/routes/factory/-functions/reexportIndex.ts

@@ -0,0 +1,2 @@
+// This file tests re-exporting a factory function from another module
+export { reexportFactory } from './reexportWrapper'

e2e/react-start/server-functions/src/routes/factory/-functions/reexportWrapper.ts

@@ -0,0 +1,12 @@
+import { createMiddleware, createServerFn } from '@tanstack/react-start'
+
+const reexportMiddleware = createMiddleware({ type: 'function' }).server(
+  ({ next }) => {
+    console.log('reexport middleware triggered')
+    return next({
+      context: { reexport: 'reexport-middleware-executed' } as const,
+    })
+  },
+)
+
+export const reexportFactory = createServerFn().middleware([reexportMiddleware])

e2e/react-start/server-functions/src/routes/factory/-functions/starReexportIndex.ts

@@ -0,0 +1,2 @@
+// This file tests re-exporting a factory function from another module using the star syntax
+export * from './starReexportWrapper'

e2e/react-start/server-functions/src/routes/factory/-functions/starReexportWrapper.ts

@@ -0,0 +1,14 @@
+import { createMiddleware, createServerFn } from '@tanstack/react-start'
+
+const starReexportMiddleware = createMiddleware({ type: 'function' }).server(
+  ({ next }) => {
+    console.log('star reexport middleware triggered')
+    return next({
+      context: { starReexport: 'star-reexport-middleware-executed' } as const,
+    })
+  },
+)
+
+export const starReexportFactory = createServerFn().middleware([
+  starReexportMiddleware,
+])

e2e/react-start/server-functions/src/routes/factory/index.tsx

@@ -12,6 +12,8 @@ import {
   fooFnPOST,
   localFn,
   localFnPOST,
+  reexportedFactoryFn,
+  starReexportedFactoryFn,
 } from './-functions/functions'
 
 export const Route = createFileRoute('/factory/')({
@@ -130,6 +132,26 @@ const functions = {
       window,
     },
   },
+  // Test that re-exported factories (using `export { foo } from './module'`) work correctly
+  // The middleware from reexportFactory should execute and add { reexport: 'reexport-middleware-executed' } to context
+  reexportedFactoryFn: {
+    fn: reexportedFactoryFn,
+    type: 'serverFn',
+    expected: {
+      name: 'reexportedFactoryFn',
+      context: { reexport: 'reexport-middleware-executed' },
+    },
+  },
+  // Test that star re-exported factories (using `export * from './module'`) work correctly
+  // The middleware from starReexportFactory should execute and add { starReexport: 'star-reexport-middleware-executed' } to context
+  starReexportedFactoryFn: {
+    fn: starReexportedFactoryFn,
+    type: 'serverFn',
+    expected: {
+      name: 'starReexportedFactoryFn',
+      context: { starReexport: 'star-reexport-middleware-executed' },
+    },
+  },
 } satisfies Record<string, TestCase>
 
 interface TestCase {

e2e/react-start/server-functions/tests/server-functions.spec.ts

@@ -543,3 +543,51 @@ test('redirect in server function called in query during SSR', async ({
   await expect(page.getByTestId('redirect-target-ssr')).toBeVisible()
   expect(page.url()).toContain('/redirect-test-ssr/target')
 })
+
+test('re-exported server function factory middleware executes correctly', async ({
+  page,
+}) => {
+  // This test specifically verifies that when a server function factory is re-exported
+  // using `export { foo } from './module'` syntax, the middleware still executes.
+  // Previously, this syntax caused middleware to be silently skipped.
+  await page.goto('/factory')
+
+  await expect(page.getByTestId('factory-route-component')).toBeInViewport()
+
+  // Click the button for the re-exported factory function
+  await page.getByTestId('btn-fn-reexportedFactoryFn').click()
+
+  // Wait for the result
+  await expect(page.getByTestId('fn-result-reexportedFactoryFn')).toContainText(
+    'reexport-middleware-executed',
+  )
+
+  // Verify the full context was returned (middleware executed)
+  await expect(
+    page.getByTestId('fn-comparison-reexportedFactoryFn'),
+  ).toContainText('equal')
+})
+
+test('star re-exported server function factory middleware executes correctly', async ({
+  page,
+}) => {
+  // This test specifically verifies that when a server function factory is re-exported
+  // using `export * from './module'` syntax, the middleware still executes.
+  // Previously, this syntax caused middleware to be silently skipped.
+  await page.goto('/factory')
+
+  await expect(page.getByTestId('factory-route-component')).toBeInViewport()
+
+  // Click the button for the star re-exported factory function
+  await page.getByTestId('btn-fn-starReexportedFactoryFn').click()
+
+  // Wait for the result
+  await expect(
+    page.getByTestId('fn-result-starReexportedFactoryFn'),
+  ).toContainText('star-reexport-middleware-executed')
+
+  // Verify the full context was returned (middleware executed)
+  await expect(
+    page.getByTestId('fn-comparison-starReexportedFactoryFn'),
+  ).toContainText('equal')
+})

packages/start-plugin-core/src/create-server-fn-plugin/compiler.ts

@@ -51,6 +51,8 @@ interface ModuleInfo {
   ast: ReturnType<typeof parseAst>
   bindings: Map<string, Binding>
   exports: Map<string, ExportEntry>
+  // Track `export * from './module'` declarations for re-export resolution
+  reExportAllSources: Array<string>
 }
 
 export class ServerFnCompiler {
@@ -86,6 +88,7 @@ export class ServerFnCompiler {
             exports: new Map(),
             code: '',
             id: libId,
+            reExportAllSources: [],
           }
           this.moduleCache.set(libId, rootModule)
         }
@@ -116,6 +119,7 @@ export class ServerFnCompiler {
 
     const bindings = new Map<string, Binding>()
     const exports = new Map<string, ExportEntry>()
+    const reExportAllSources: Array<string> = []
 
     // we are only interested in top-level bindings, hence we don't traverse the AST
     // instead we only iterate over the program body
@@ -178,6 +182,16 @@ export class ServerFnCompiler {
               ? sp.exported.name
               : sp.exported.value
             exports.set(exported, { tag: 'Normal', name: local })
+
+            // When re-exporting from another module (export { foo } from './module'),
+            // create an import binding so the server function can be resolved
+            if (node.source) {
+              bindings.set(local, {
+                type: 'import',
+                source: node.source.value,
+                importedName: local,
+              })
+            }
           }
         }
       } else if (t.isExportDefaultDeclaration(node)) {
@@ -189,10 +203,21 @@ export class ServerFnCompiler {
           bindings.set(synth, { type: 'var', init: d as t.Expression })
           exports.set('default', { tag: 'Default', name: synth })
         }
+      } else if (t.isExportAllDeclaration(node)) {
+        // Handle `export * from './module'` syntax
+        // Track the source so we can look up exports from it when needed
+        reExportAllSources.push(node.source.value)
       }
     }
 
-    const info: ModuleInfo = { code, id, ast, bindings, exports }
+    const info: ModuleInfo = {
+      code,
+      id,
+      ast,
+      bindings,
+      exports,
+      reExportAllSources,
+    }
     this.moduleCache.set(id, info)
     return info
   }
@@ -343,7 +368,43 @@ export class ServerFnCompiler {
 
       const importedModule = await this.getModuleInfo(target)
 
+      // Try to find the export in the module's direct exports
       const moduleExport = importedModule.exports.get(binding.importedName)
+
+      // If not found directly, check re-export-all sources (`export * from './module'`)
+      if (!moduleExport && importedModule.reExportAllSources.length > 0) {
+        for (const reExportSource of importedModule.reExportAllSources) {
+          const reExportTarget = await this.options.resolveId(
+            reExportSource,
+            importedModule.id,
+          )
+          if (reExportTarget) {
+            const reExportModule = await this.getModuleInfo(reExportTarget)
+            const reExportEntry = reExportModule.exports.get(
+              binding.importedName,
+            )
+            if (reExportEntry) {
+              // Found the export in a re-exported module, resolve from there
+              const reExportBinding = reExportModule.bindings.get(
+                reExportEntry.name,
+              )
+              if (reExportBinding) {
+                if (reExportBinding.resolvedKind) {
+                  return reExportBinding.resolvedKind
+                }
+                const resolvedKind = await this.resolveBindingKind(
+                  reExportBinding,
+                  reExportModule.id,
+                  visited,
+                )
+                reExportBinding.resolvedKind = resolvedKind
+                return resolvedKind
+              }
+            }
+          }
+        }
+      }
+
       if (!moduleExport) {
         return 'None'
       }