fix(webapp): surface project rename failures on the form

The two json({ errors: { body } }) returns aren't a conform
SubmissionResult, so conform reset the form and discarded them — the
last way to fail this form with nothing on screen. Return
submission.reply({ formErrors }) and render the rename form's
form-level errors, matching the delete form on the same page.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: claude

.server-changes/fix-project-settings-toast.md

@@ -3,4 +3,4 @@ area: webapp
 type: fix
 ---
 
-Renaming a project now keeps you on the project settings page and shows a message explaining the result, instead of silently moving you to the tasks page.
+Renaming a project now keeps you on the project settings page and tells you what happened, instead of silently moving you to the tasks page or clearing the form with no explanation.

apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.settings.general/route.tsx

@@ -105,7 +105,7 @@ export const action = dashboardAction(
     );
 
     if (membershipResultOrFail.isErr()) {
-      return json({ errors: { body: membershipResultOrFail.error.type } }, { status: 404 });
+      return json(submission.reply({ formErrors: ["Project not found"] }), { status: 404 });
     }
 
     const { projectId } = membershipResultOrFail.value;
@@ -133,7 +133,9 @@ export const action = dashboardAction(
               logger.error("Failed to rename project", {
                 error: resultOrFail.error,
               });
-              return json({ errors: { body: "Failed to rename project" } }, { status: 400 });
+              return json(submission.reply({ formErrors: ["Failed to rename project"] }), {
+                status: 400,
+              });
             }
           }
         }
@@ -257,6 +259,7 @@ export default function GeneralSettingsPage() {
                     }}
                   />
                   <FormError id={projectName.errorId}>{projectName.errors}</FormError>
+                  <FormError>{renameForm.errors}</FormError>
                 </InputGroup>
                 <FormButtons
                   confirmButton={

apps/webapp/test/projectSettingsToastRedirect.test.ts

@@ -4,7 +4,7 @@
 // never renders the toast. The general settings action must therefore redirect to a page
 // that renders.
 
-import { okAsync } from "neverthrow";
+import { errAsync, okAsync } from "neverthrow";
 import { describe, expect, it, vi } from "vitest";
 import { commitSession, getSession, redirectWithErrorMessage } from "~/models/message.server";
 import { action as generalSettingsAction } from "~/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.settings.general/route";
@@ -18,11 +18,16 @@ vi.mock("~/models/organization.server", () => ({
   resolveOrgIdFromSlug: vi.fn().mockResolvedValue("org_1"),
 }));
 
+const renameFails = { value: false };
+
 vi.mock("~/services/projectSettings.server", () => ({
   ProjectSettingsService: class {
     verifyProjectMembership() {
       return okAsync({ projectId: "proj_1" });
     }
+    renameProject() {
+      return renameFails.value ? errAsync({ type: "other" as const }) : okAsync(undefined);
+    }
     deleteProject() {
       return okAsync(undefined);
     }
@@ -105,3 +110,16 @@ describe("general settings redirects target a page that renders", () => {
     expect(response.headers.get("Location")).toBe(ORG_PATH);
   });
 });
+
+describe("general settings failures reach the form", () => {
+  it("returns a form-level error when the rename fails", async () => {
+    renameFails.value = true;
+    const response = await runAction("rename", true);
+    renameFails.value = false;
+
+    expect(response.status).toBe(400);
+    expect(await response.json()).toMatchObject({
+      error: { "": ["Failed to rename project"] },
+    });
+  });
+});