fix: retain uncertain optimistic mutations

tests/features/reference-feature/reference-page.test.tsx

@@ -281,6 +281,7 @@ describe("reference feature page states", () => {
         "CONFLICT",
         "CREATE_REFERENCE_RESOURCE",
         0,
+        { effect: "NOT_APPLIED" },
       ),
     });
     expect(await screen.findByText(/다른 변경과 충돌했습니다/)).toBeVisible();
@@ -290,6 +291,112 @@ describe("reference feature page states", () => {
     expect(screen.getByLabelText("설명")).toHaveValue("Keep this input");
   });
 
+  it("blocks resubmit and exposes only reconciliation for an unknown create effect", async () => {
+    const user = userEvent.setup();
+    const createResource = vi.fn(async () => ({
+      ok: false as const,
+      error: createFailure(
+        "SERVER_FAILURE",
+        "CREATE_REFERENCE_RESOURCE",
+        0,
+        { effect: "MAYBE_APPLIED" },
+      ),
+    }));
+    renderReference(
+      inputWith({ createResource }),
+      "/examples/reference-resources/new",
+    );
+    await user.type(
+      await screen.findByRole("textbox", { name: /새 항목 이름/ }),
+      "Unknown result",
+    );
+    await user.click(screen.getByRole("button", { name: "저장" }));
+
+    expect(
+      await screen.findByText("변경 결과를 확인할 수 없습니다."),
+    ).toBeVisible();
+    expect(screen.getByRole("button", { name: "저장" })).toBeDisabled();
+    expect(
+      screen.queryByText("저장하지 못했습니다. 잠시 후 다시 시도해 주세요."),
+    ).not.toBeInTheDocument();
+    await user.click(screen.getByRole("button", { name: "저장" }));
+    expect(createResource).toHaveBeenCalledOnce();
+    expect(
+      screen.getByRole("textbox", { name: /새 항목 이름/ }),
+    ).toHaveValue("Unknown result");
+
+    await user.click(
+      screen.getByRole("button", { name: "변경되지 않음으로 확인" }),
+    );
+    await waitFor(() =>
+      expect(screen.getByRole("button", { name: "저장" })).toBeEnabled(),
+    );
+    expect(createResource).toHaveBeenCalledOnce();
+    expect(
+      screen.getByRole("textbox", { name: /새 항목 이름/ }),
+    ).toHaveValue("Unknown result");
+  });
+
+  it("settles the form after confirming an unknown create was applied", async () => {
+    const user = userEvent.setup();
+    const createResource = vi.fn(async () => ({
+      ok: false as const,
+      error: createFailure(
+        "SERVER_FAILURE",
+        "CREATE_REFERENCE_RESOURCE",
+        0,
+        { effect: "MAYBE_APPLIED" },
+      ),
+    }));
+    renderReference(
+      inputWith({ createResource }),
+      "/examples/reference-resources/new",
+    );
+    const name = await screen.findByRole("textbox", {
+      name: /새 항목 이름/,
+    });
+    await user.type(name, "Already created");
+    await user.click(screen.getByRole("button", { name: "저장" }));
+    await user.click(
+      await screen.findByRole("button", { name: "변경됨으로 확인" }),
+    );
+
+    expect(await screen.findByRole("status")).toHaveTextContent("저장했습니다.");
+    expect(name).toHaveValue("");
+    await user.click(screen.getByRole("button", { name: "저장" }));
+    expect(createResource).toHaveBeenCalledOnce();
+  });
+
+  it("treats an applied-confirmed failure as a settled create", async () => {
+    const user = userEvent.setup();
+    const createResource = vi.fn(async () => ({
+      ok: false as const,
+      error: createFailure(
+        "SERVER_FAILURE",
+        "CREATE_REFERENCE_RESOURCE",
+        0,
+        { effect: "APPLIED_CONFIRMED" },
+      ),
+    }));
+    renderReference(
+      inputWith({ createResource }),
+      "/examples/reference-resources/new",
+    );
+    const name = await screen.findByRole("textbox", {
+      name: /새 항목 이름/,
+    });
+    await user.type(name, "Committed despite response");
+    await user.click(screen.getByRole("button", { name: "저장" }));
+
+    expect(await screen.findByRole("status")).toHaveTextContent("저장했습니다.");
+    expect(name).toHaveValue("");
+    expect(
+      screen.queryByText("저장하지 못했습니다. 잠시 후 다시 시도해 주세요."),
+    ).not.toBeInTheDocument();
+    await user.click(screen.getByRole("button", { name: "저장" }));
+    expect(createResource).toHaveBeenCalledOnce();
+  });
+
   it("keeps stale data visible during refresh failure and recovers on retry", async () => {
     const user = userEvent.setup();
     const listResources = vi