fix(next): skip eager discovery in deferred build mode

.changeset/slow-bottles-pull.md

@@ -0,0 +1,5 @@
+---
+'@workflow/next': patch
+---
+
+Stop eager input-graph directive discovery in deferred Next.js builds and rely on loader/socket-driven discovery with `onBeforeDeferredEntries`.

packages/core/e2e/dev.test.ts

@@ -412,6 +412,63 @@ ${apiFileContent}`
         });
       }
     );
+
+    test.skipIf(!supportsDeferredStepCopies)(
+      'should copy package step sources discovered via manifest entries',
+      { timeout: 30_000 },
+      async () => {
+        const workflowManifestPath = path.join(
+          appPath,
+          'app/.well-known/workflow/v1/manifest.json'
+        );
+        const copiedStepDir = path.join(
+          path.dirname(generatedStep),
+          '__workflow_step_files__'
+        );
+
+        await pollUntil({
+          description:
+            'copied deferred step files to include @workflow/ai package steps',
+          timeoutMs: 25_000,
+          check: async () => {
+            await fetchWithTimeout('/api/chat');
+            const manifestJson = await fs.readFile(
+              workflowManifestPath,
+              'utf8'
+            );
+            const manifest = JSON.parse(manifestJson) as {
+              steps?: Record<string, unknown>;
+            };
+            const manifestStepFiles = Object.keys(manifest.steps || {});
+            expect(
+              manifestStepFiles.some((filePath) =>
+                filePath.includes('ai/dist/agent/durable-agent.js')
+              )
+            ).toBe(true);
+
+            const copiedStepFileNames = await fs.readdir(copiedStepDir);
+            const copiedStepContents = await Promise.all(
+              copiedStepFileNames.map(async (copiedStepFileName) => {
+                const copiedStepFilePath = path.join(
+                  copiedStepDir,
+                  copiedStepFileName
+                );
+                const copiedStepStats = await fs.stat(copiedStepFilePath);
+                if (!copiedStepStats.isFile()) {
+                  return '';
+                }
+                return await fs.readFile(copiedStepFilePath, 'utf8');
+              })
+            );
+            expect(
+              copiedStepContents.some((content) =>
+                content.includes('async function closeStream')
+              )
+            ).toBe(true);
+          },
+        });
+      }
+    );
   });
 }
 

packages/core/e2e/local-build.test.ts

@@ -83,6 +83,14 @@ const ESM_STEP_BUNDLE_PROJECTS: Record<string, string> = {
     '.vercel/output/functions/.well-known/workflow/v1/step.func/index.mjs',
 };
 
+const DEFERRED_BUILD_MODE_PROJECTS = new Set([
+  'nextjs-webpack',
+  'nextjs-turbopack',
+]);
+const DEFERRED_BUILD_UNSUPPORTED_WARNING =
+  'Enabled lazyDiscovery but Next.js version is not compatible';
+const EAGER_DISCOVERY_LOG = 'Discovering workflow directives';
+
 describe.each([
   'example',
   'nextjs-webpack',
@@ -111,6 +119,15 @@ describe.each([
 
     expect(result.output).not.toContain('Error:');
 
+    if (DEFERRED_BUILD_MODE_PROJECTS.has(project)) {
+      const deferredBuildSupported = !result.output.includes(
+        DEFERRED_BUILD_UNSUPPORTED_WARNING
+      );
+      if (deferredBuildSupported) {
+        expect(result.output).not.toContain(EAGER_DISCOVERY_LOG);
+      }
+    }
+
     if (usesVercelWorld()) {
       const diagnosticsManifestPath = path.join(
         getWorkbenchAppPath(project),