diff --git a/packages/app/src/onboarding/internal/model.test.ts b/packages/app/src/onboarding/internal/model.test.ts
index ee3a8b00c9..5838876e91 100644
--- a/packages/app/src/onboarding/internal/model.test.ts
+++ b/packages/app/src/onboarding/internal/model.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import {
   createOnboardingModel,
   type OnboardingCompletionStorage,
@@ -134,7 +134,6 @@ describe("onboarding model", () => {
     advance(model);
     advance(model);
     advance(model);
-    advance(model);
     expect(model.getState()).toMatchObject({ stepIndex: 3 });
     model.goTo("providers");
     expect(model.getState()).toMatchObject({ stepIndex: 1 });
@@ -162,6 +161,25 @@ describe("onboarding model", () => {
     expect(model.getState()).toMatchObject({ status: "open", stepIndex: 2 });
   });
 
+  it("moving on from the last step finishes setup, unless the user left that step first", async () => {
+    const storage = new MemoryCompletionStorage();
+    const model = await openModel(storage);
+    model.applySetupHost(FRESH_HOST, { includePhoneStep: false });
+    model.goTo("orchestration");
+
+    // Finish is applying choices when the user goes back to Projects.
+    const finishingFrom = currentVisit(model);
+    model.back();
+    model.next(finishingFrom);
+    expect(model.getState()).toMatchObject({ status: "open", stepIndex: 2 });
+    expect(storage.completed).toBe(false);
+
+    advance(model);
+    advance(model);
+    await vi.waitFor(() => expect(storage.completed).toBe(true));
+    expect(model.getState()).toEqual({ status: "hidden" });
+  });
+
   it("records completion when setup closes, so it does not open again", async () => {
     const storage = new MemoryCompletionStorage();
     const model = await openModel(storage);
diff --git a/packages/app/src/onboarding/internal/model.ts b/packages/app/src/onboarding/internal/model.ts
index 1ac2f01f4a..f8aaf46d4f 100644
--- a/packages/app/src/onboarding/internal/model.ts
+++ b/packages/app/src/onboarding/internal/model.ts
@@ -46,8 +46,9 @@ export interface OnboardingModel {
   applySetupHost(host: OnboardingSetupHost | null, options: OnboardingStepOptions): void;
   reopen(serverId: string, options: OnboardingStepOptions): void;
   /**
-   * Moves on from the step visit the caller saw. A no-op once that visit ended, so an action that
-   * finishes late never moves a step the user left or a setup they closed and reopened.
+   * Moves on from the step visit the caller saw; from the last step, that finishes setup. A no-op
+   * once that visit ended, so an action that finishes late never moves a step the user left or
+   * closes a setup they went back in, or closed and reopened.
    */
   next(visit: number): void;
   back(): void;
@@ -129,6 +130,12 @@ export function createOnboardingModel(input: {
 
   const ready = loadCompletion();
 
+  async function complete() {
+    completion = "completed";
+    setState({ status: "hidden" });
+    await input.storage.markCompleted();
+  }
+
   return {
     ready,
     getState: () => state,
@@ -146,7 +153,9 @@ export function createOnboardingModel(input: {
       setState(openState(serverId, options));
     },
     next(visit) {
-      if (state.status === "open" && state.visit === visit) moveTo(state.stepIndex + 1);
+      if (state.status !== "open" || state.visit !== visit) return;
+      if (state.stepIndex === state.steps.length - 1) void complete();
+      else moveTo(state.stepIndex + 1);
     },
     back() {
       if (state.status === "open") moveTo(state.stepIndex - 1);
@@ -156,10 +165,6 @@ export function createOnboardingModel(input: {
       const stepIndex = state.steps.indexOf(step);
       if (stepIndex >= 0) moveTo(stepIndex);
     },
-    async complete() {
-      completion = "completed";
-      setState({ status: "hidden" });
-      await input.storage.markCompleted();
-    },
+    complete,
   };
 }
diff --git a/packages/app/src/onboarding/internal/onboarding-modal.tsx b/packages/app/src/onboarding/internal/onboarding-modal.tsx
index c36c4855f1..0eb0418185 100644
--- a/packages/app/src/onboarding/internal/onboarding-modal.tsx
+++ b/packages/app/src/onboarding/internal/onboarding-modal.tsx
@@ -42,11 +42,8 @@ export function OnboardingModal({ model, state }: { model: OnboardingModel; stat
   }, [model]);
   const handleBack = useCallback(() => model.back(), [model]);
   const { visit } = state;
-  // Moving on from the last step finishes setup; any step's own work runs before that.
-  const handleAdvance = useCallback(() => {
-    if (isLast) void model.complete();
-    else model.next(visit);
-  }, [isLast, model, visit]);
+  // A step's own work runs before it moves on; from the last step, moving on finishes setup.
+  const handleAdvance = useCallback(() => model.next(visit), [model, visit]);
   const handleAddSuggestions = useCallback(() => {
     void (async () => {
       if (await addChecked()) handleAdvance();