fix(workflows): one workflow step per LLM call so runs stop blowing the 800s ceiling

app/lib/workflows/__tests__/runAgentStepStreaming.test.ts

@@ -0,0 +1,118 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { streamText } from "ai";
+import { runAgentStep } from "@/app/lib/workflows/runAgentStep";
+import { persistAssistantMessage } from "@/lib/chat/persistAssistantMessage";
+
+vi.mock("ai", async () => {
+  const actual = await vi.importActual<typeof import("ai")>("ai");
+  return { ...actual, streamText: vi.fn() };
+});
+vi.mock("@ai-sdk/gateway", () => ({
+  gateway: vi.fn((modelId: string) => ({ modelId, __mock: "gateway" })),
+}));
+vi.mock("@/lib/chat/persistAssistantMessage", () => ({
+  persistAssistantMessage: vi.fn(),
+}));
+vi.mock("workflow", () => ({
+  getWorkflowMetadata: vi.fn(() => ({
+    workflowRunId: "test-run-id",
+    workflowName: "test",
+    workflowStartedAt: new Date(0),
+    url: "https://example.test",
+  })),
+}));
+vi.mock("@/lib/chat/pollWorkflowCancellation", () => ({
+  pollWorkflowCancellation: vi.fn(() => ({ stop: vi.fn(), done: Promise.resolve() })),
+}));
+vi.mock("workflow/api", () => ({
+  getRun: vi.fn(() => ({
+    get status() {
+      return Promise.resolve("running");
+    },
+  })),
+}));
+
+const baseInput = {
+  modelMessages: [{ role: "user" as const, content: "hi" }],
+  originalMessages: [
+    { id: "m1", role: "user" as const, parts: [{ type: "text" as const, text: "hi" }] },
+  ],
+  modelId: "anthropic/claude-haiku-4.5",
+  agentContext: {
+    sandbox: { state: { type: "vercel" }, workingDirectory: "/sandbox/mono" },
+  },
+  assistantMessageId: "asst-test-id",
+};
+
+function makeWritable() {
+  const written: unknown[] = [];
+  const stream = new WritableStream({
+    write(chunk) {
+      written.push(chunk);
+    },
+  });
+  return { stream, written };
+}
+
+beforeEach(() => vi.clearAllMocks());
+
+describe("runAgentStep — streaming shape (mirrors upstream open-agents)", () => {
+  it("writes every stream part straight to the shared writable", async () => {
+    const parts = [
+      { type: "text-start", id: "t1" },
+      { type: "text-delta", id: "t1", delta: "hello" },
+      { type: "text-end", id: "t1" },
+    ];
+    vi.mocked(streamText).mockReturnValue({
+      toUIMessageStream: vi.fn(() =>
+        (async function* () {
+          for (const p of parts) yield p;
+        })(),
+      ),
+      finishReason: Promise.resolve("stop"),
+      response: Promise.resolve({ messages: [] }),
+    } as never);
+    const { stream, written } = makeWritable();
+
+    await runAgentStep({ ...baseInput, writable: stream } as never);
+
+    expect(written).toEqual(parts);
+  });
+
+  // Persistence moved to the workflow body. Keeping it in the step is what
+  // required the outer createUIMessageStream wrapper, and that wrapper is
+  // what dropped every tool call from the transcript (chat#1918).
+  it("does not persist from inside the step", async () => {
+    vi.mocked(streamText).mockReturnValue({
+      toUIMessageStream: vi.fn(() => (async function* () {})()),
+      finishReason: Promise.resolve("stop"),
+      response: Promise.resolve({ messages: [] }),
+    } as never);
+    const { stream } = makeWritable();
+
+    await runAgentStep({ ...baseInput, writable: stream } as never);
+
+    expect(persistAssistantMessage).not.toHaveBeenCalled();
+  });
+
+  it("reports aborted and does not rethrow when the stream aborts", async () => {
+    const abortError = Object.assign(new Error("aborted"), { name: "AbortError" });
+    vi.mocked(streamText).mockReturnValue({
+      toUIMessageStream: vi.fn(() =>
+        (async function* () {
+          yield { type: "text-start", id: "t1" };
+          throw abortError;
+        })(),
+      ),
+      finishReason: Promise.reject(abortError),
+      response: Promise.reject(abortError),
+    } as never);
+    const { stream } = makeWritable();
+
+    const result = await runAgentStep({ ...baseInput, writable: stream } as never);
+
+    expect(result.aborted).toBe(true);
+    expect(result.finishReason).toBe("stop");
+    expect(result.responseMessages).toEqual([]);
+  });
+});

app/lib/workflows/__tests__/runAgentWorkflow.test.ts

@@ -23,6 +23,15 @@ vi.mock("@/app/lib/workflows/closeChatStream", () => ({
 vi.mock("@/app/lib/workflows/generateAssistantMessageId", () => ({
   generateAssistantMessageId: vi.fn(),
 }));
+// The loop's supporting steps — exercised in runAgentWorkflowLoop.test.ts.
+vi.mock("@/app/lib/workflows/convertMessagesStep", () => ({
+  convertMessagesStep: vi.fn(() => Promise.resolve([])),
+}));
+vi.mock("@/app/lib/workflows/persistAssistantMessageStep", () => ({
+  persistAssistantMessageStep: vi.fn(),
+}));
+vi.mock("@/app/lib/workflows/sendStreamStart", () => ({ sendStreamStart: vi.fn() }));
+vi.mock("@/app/lib/workflows/sendStreamFinish", () => ({ sendStreamFinish: vi.fn() }));
 vi.mock("@/lib/credits/handleChatCredits", () => ({
   handleChatCredits: vi.fn(),
 }));
@@ -76,6 +85,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
@@ -98,6 +108,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
@@ -117,6 +128,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
@@ -129,6 +141,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
@@ -147,22 +160,28 @@ describe("runAgentWorkflow", () => {
     expect(closeChatStream).toHaveBeenCalledWith(writableStub);
   });
 
-  it("forwards chatId to runAgentStep so it can persist the assistant message per step", async () => {
+  // Persistence moved to the workflow body, so the step has no business
+  // knowing the chat id. Guards against re-coupling them.
+  it("does NOT pass chatId to runAgentStep — persistence is the workflow body's job", async () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
     await runAgentWorkflow(baseInput);
 
-    expect(runAgentStep).toHaveBeenCalledWith(expect.objectContaining({ chatId: "chat-1" }));
+    expect(runAgentStep).toHaveBeenCalledWith(
+      expect.not.objectContaining({ chatId: expect.anything() }),
+    );
   });
 
   it("generates a fresh assistantMessageId via the step and forwards it to runAgentStep", async () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
@@ -178,6 +197,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
@@ -218,6 +238,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: responseMessage as never,
     });
 
@@ -247,6 +268,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: responseMessage as never,
     });
 
@@ -266,6 +288,7 @@ describe("runAgentWorkflow", () => {
     vi.mocked(runAgentStep).mockResolvedValue({
       finishReason: "stop",
       aborted: false,
+      responseMessages: [],
       responseMessage: undefined,
     });
 
@@ -292,6 +315,7 @@ describe("runAgentWorkflow", () => {
       vi.mocked(runAgentStep).mockResolvedValue({
         finishReason: "stop",
         aborted: false,
+        responseMessages: [],
         responseMessage: responseMessageWithMetadata,
       });
 
@@ -308,6 +332,7 @@ describe("runAgentWorkflow", () => {
           responseMessage: responseMessageWithMetadata,
           finishReason: "stop",
           aborted: false,
+          responseMessages: [],
           sessionId: "session-1",
           sessionTitle: "test session",
           repoOwner: "recoupable",
@@ -321,6 +346,7 @@ describe("runAgentWorkflow", () => {
       vi.mocked(runAgentStep).mockResolvedValue({
         finishReason: "stop",
         aborted: false,
+        responseMessages: [],
         responseMessage: responseMessageWithMetadata,
       });
 
@@ -334,6 +360,7 @@ describe("runAgentWorkflow", () => {
       vi.mocked(runAgentStep).mockResolvedValue({
         finishReason: "stop",
         aborted: false,
+        responseMessages: [],
         responseMessage: responseMessageWithMetadata,
       });
 
@@ -350,6 +377,7 @@ describe("runAgentWorkflow", () => {
       vi.mocked(runAgentStep).mockResolvedValue({
         finishReason: "stop",
         aborted: false,
+        responseMessages: [],
         responseMessage: undefined,
       });
 
@@ -378,6 +406,7 @@ describe("runAgentWorkflow", () => {
       vi.mocked(runAgentStep).mockResolvedValue({
         finishReason: "stop",
         aborted: true,
+        responseMessages: [],
         responseMessage: abortedResponseMessage as never,
       });
 
@@ -398,6 +427,7 @@ describe("runAgentWorkflow", () => {
       vi.mocked(runAgentStep).mockResolvedValue({
         finishReason: "stop",
         aborted: true,
+        responseMessages: [],
         responseMessage: abortedResponseMessage as never,
       });
 
@@ -410,6 +440,7 @@ describe("runAgentWorkflow", () => {
       vi.mocked(runAgentStep).mockResolvedValue({
         finishReason: "stop",
         aborted: true,
+        responseMessages: [],
         responseMessage: abortedResponseMessage as never,
       });