diff --git a/src/components/GitHubSkillSyncConfiguration.tsx b/src/components/GitHubSkillSyncConfiguration.tsx
index 140c24f6..c8e88f8d 100644
--- a/src/components/GitHubSkillSyncConfiguration.tsx
+++ b/src/components/GitHubSkillSyncConfiguration.tsx
@@ -6,7 +6,7 @@ import { Input } from "./ui/input";
 import { Label } from "./ui/label";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "./ui/select";
 
-export type GitHubSkillSyncPublisherOption = {
+type GitHubSkillSyncPublisherOption = {
   publisher: {
     _id: Id<"publishers">;
     handle: string;
@@ -27,7 +27,7 @@ export type GitHubSkillSyncRepository = {
   unavailableReason: "disabled" | null;
 };
 
-export type GitHubSkillSyncPreviewItem = {
+type GitHubSkillSyncPreviewItem = {
   slug: string;
   displayName: string;
   path: string;
@@ -297,6 +297,7 @@ function classificationLabel(classification: GitHubSkillSyncPreviewItem["classif
     case "ownership-conflict":
       return "Ownership conflict";
   }
+  return assertNever(classification);
 }
 
 function classificationTone(classification: GitHubSkillSyncPreviewItem["classification"]) {
@@ -309,6 +310,11 @@ function classificationTone(classification: GitHubSkillSyncPreviewItem["classifi
     case "ownership-conflict":
       return "text-status-error-fg";
   }
+  return assertNever(classification);
+}
+
+function assertNever(value: never): never {
+  throw new Error(`Unsupported GitHub Skill Sync classification: ${String(value)}`);
 }
 
 function previewReasonLabel(reason: string) {
diff --git a/src/routes/-settings.test.tsx b/src/routes/-settings.test.tsx
index 82503c48..6f42feb7 100644
--- a/src/routes/-settings.test.tsx
+++ b/src/routes/-settings.test.tsx
@@ -1,5 +1,5 @@
 /* @vitest-environment jsdom */
-import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import { act, fireEvent, render, screen, waitFor } from "@testing-library/react";
 import { getFunctionName } from "convex/server";
 import type { FunctionReturnType } from "convex/server";
 import type { ReactNode } from "react";
@@ -801,6 +801,93 @@ describe("Settings", () => {
     ).toBe(true);
   });
 
+  it("ignores a preview response after the selected repository changes", async () => {
+    const listRepositories = vi.fn().mockResolvedValue({
+      publisher: { _id: "publisher_patrick", handle: "patrick", kind: "user" },
+      page: 1,
+      perPage: 100,
+      hasMore: false,
+      repositories: [
+        {
+          repositoryId: "1",
+          repo: "patrick-erichsen/skills",
+          ownerId: "123",
+          ownerLogin: "patrick-erichsen",
+          defaultBranch: "main",
+          archived: false,
+          disabled: false,
+          fork: false,
+          pushedAt: "2026-07-23T12:00:00Z",
+          selectable: true,
+          unavailableReason: null,
+        },
+      ],
+    });
+    let resolvePreview: ((value: unknown) => void) | undefined;
+    const previewRepository = vi.fn(
+      () =>
+        new Promise((resolve) => {
+          resolvePreview = resolve;
+        }),
+    );
+    useActionMock.mockImplementation((action) => {
+      const actionName = getFunctionName(action);
+      if (actionName === "githubSkillSyncSettings:listRepositories") return listRepositories;
+      if (actionName === "githubSkillSyncSettings:previewRepository") return previewRepository;
+      return vi.fn();
+    });
+    mockSignedInSettings({
+      search: { view: "githubSources" },
+      memberships: [personalMembership],
+    });
+
+    render(<Settings />);
+
+    await waitFor(() => expect(listRepositories).toHaveBeenCalled());
+    fireEvent.click(screen.getByRole("button", { name: "Preview repository" }));
+    await waitFor(() => expect(previewRepository).toHaveBeenCalled());
+
+    fireEvent.change(screen.getByLabelText("Repository URL"), {
+      target: { value: "patrick-erichsen/other-skills" },
+    });
+    await act(async () => {
+      resolvePreview?.({
+        publisher: { _id: "publisher_patrick", handle: "patrick", kind: "user" },
+        repository: {
+          requestedRepo: "patrick-erichsen/skills",
+          repositoryId: "1",
+          repo: "patrick-erichsen/skills",
+          redirected: false,
+          defaultBranch: "main",
+          commit: "a".repeat(40),
+        },
+        summary: {
+          total: 1,
+          newDestinations: 1,
+          replacements: 0,
+          unavailable: 0,
+          conflicts: 0,
+        },
+        items: [
+          {
+            slug: "html",
+            displayName: "HTML",
+            path: "skills/html",
+            contentHash: "hash-html",
+            classification: "new-destination",
+            eligible: true,
+            destination: null,
+          },
+        ],
+      });
+    });
+
+    expect(screen.getByLabelText<HTMLInputElement>("Repository URL").value).toBe(
+      "patrick-erichsen/other-skills",
+    );
+    expect(screen.queryByRole("heading", { name: "Repository preview" })).toBeNull();
+  });
+
   it("shows synced repos as separate cards and lets owners delete a source", async () => {
     const deleteSource = vi.fn().mockResolvedValue({ ok: true, deletedSkills: 0 });
     useMutationMock.mockImplementation((mutation) =>
diff --git a/src/routes/settings.tsx b/src/routes/settings.tsx
index d89ab78f..9e0a42f2 100644
--- a/src/routes/settings.tsx
+++ b/src/routes/settings.tsx
@@ -36,6 +36,7 @@ import {
   type FormEvent,
   type ReactNode,
   useEffect,
+  useRef,
   useState,
 } from "react";
 import { toast } from "sonner";
@@ -331,6 +332,7 @@ export function Settings() {
   const [isLoadingGitHubRepositories, setIsLoadingGitHubRepositories] = useState(false);
   const [githubSyncPreview, setGitHubSyncPreview] = useState<GitHubSkillSyncPreview | null>(null);
   const [isPreviewingGitHubSource, setIsPreviewingGitHubSource] = useState(false);
+  const githubSyncPreviewRequestId = useRef(0);
   const [deletingSourceId, setDeletingSourceId] = useState<Id<"githubSkillSources"> | null>(null);
   const [sourceToDelete, setSourceToDelete] = useState<GitHubSkillSource | null>(null);
   const [deleteDialogOpen, setDeleteDialogOpen] = useState(false);
@@ -472,7 +474,7 @@ export function Settings() {
     ) {
       setGitHubRepositories([]);
       setGitHubRepositoriesError(null);
-      return;
+      return undefined;
     }
     let cancelled = false;
     setIsLoadingGitHubRepositories(true);
@@ -788,6 +790,8 @@ export function Settings() {
     if (!selectedSourcePublisher) return;
     const repo = parseGitHubRepoInput(githubRepo);
     if (!repo) return;
+    const requestId = githubSyncPreviewRequestId.current + 1;
+    githubSyncPreviewRequestId.current = requestId;
     setIsPreviewingGitHubSource(true);
     setGitHubSyncPreview(null);
     try {
@@ -795,12 +799,16 @@ export function Settings() {
         publisherId: selectedSourcePublisher.publisher._id,
         repo,
       });
+      if (githubSyncPreviewRequestId.current !== requestId) return;
       setGithubRepo(result.repository.repo);
       setGitHubSyncPreview(result as GitHubSkillSyncPreview);
     } catch (error) {
+      if (githubSyncPreviewRequestId.current !== requestId) return;
       toast.error(getUserFacingConvexError(error, "GitHub repository could not be previewed."));
     } finally {
-      setIsPreviewingGitHubSource(false);
+      if (githubSyncPreviewRequestId.current === requestId) {
+        setIsPreviewingGitHubSource(false);
+      }
     }
   }
 
@@ -1706,17 +1714,21 @@ export function Settings() {
                         publisherOptions={githubSourcePublishers}
                         selectedPublisherId={selectedSourcePublisher.publisher._id}
                         onPublisherChange={(publisherId) => {
+                          githubSyncPreviewRequestId.current += 1;
                           setSelectedSourcePublisherId(publisherId);
                           setGithubRepo("");
                           setGitHubSyncPreview(null);
+                          setIsPreviewingGitHubSource(false);
                         }}
                         repositories={githubRepositories}
                         repositoriesError={githubRepositoriesError}
                         isLoadingRepositories={isLoadingGitHubRepositories}
                         githubRepo={githubRepo}
                         onGithubRepoChange={(repo) => {
+                          githubSyncPreviewRequestId.current += 1;
                           setGithubRepo(repo);
                           setGitHubSyncPreview(null);
+                          setIsPreviewingGitHubSource(false);
                         }}
                         onPreview={onPreviewGitHubSource}
                         isPreviewing={isPreviewingGitHubSource}