Create flow centralization and cleanup

app/(app)/create/utils/createFlowPaths.ts

@@ -0,0 +1,78 @@
+/**
+ * Central `/create/...` path builders (Linear CR-92 §2).
+ * Prefer these over string literals so layout, redirects, hooks, and tests stay aligned.
+ */
+
+import type { CreateFlowStep } from "../types";
+import { CREATE_FLOW_REVIEW_RETURN_QUERY_KEY } from "./flowSteps";
+
+export const CREATE_ROUTES = {
+  root: "/",
+  createRoot: "/create",
+  /** First step resolves via redirect from `/create`. */
+  createFirstStep: "/create",
+  review: "/create/review",
+  finalReview: "/create/final-review",
+  completed: "/create/completed",
+  editRule: "/create/edit-rule",
+} as const;
+
+/**
+ * Post-login return and session-gate paths on wizard steps.
+ * (Also used when `pathname` is unknown but `syncDraft` must be appended.)
+ */
+export const CREATE_FLOW_SYNC_DRAFT_QUERY = "syncDraft" as const;
+export const CREATE_FLOW_SYNC_DRAFT_VALUE = "1" as const;
+
+export function createFlowStepPathWithSyncDraft(step: CreateFlowStep): string {
+  return createFlowStepPath(step, {
+    [CREATE_FLOW_SYNC_DRAFT_QUERY]: CREATE_FLOW_SYNC_DRAFT_VALUE,
+  });
+}
+
+export type CreateFlowPathQuery = Record<
+  string,
+  string | number | boolean | undefined
+>;
+
+/**
+ * Path for a wizard step: `/create/{screenId}` with optional query string.
+ */
+export function createFlowStepPath(
+  step: CreateFlowStep,
+  query?: CreateFlowPathQuery,
+): string {
+  const base = `/create/${step}`;
+  if (query == null || Object.keys(query).length === 0) return base;
+  const sp = new URLSearchParams();
+  for (const [k, v] of Object.entries(query)) {
+    if (v === undefined) continue;
+    sp.set(k, String(v));
+  }
+  const q = sp.toString();
+  return q.length > 0 ? `${base}?${q}` : base;
+}
+
+export function createCompletedPath(query?: CreateFlowPathQuery): string {
+  return createFlowStepPath("completed", query);
+}
+
+/**
+ * Navigate back from a facet step to final-review / edit-rule, dropping
+ * `reviewReturn` from the current query while preserving other params.
+ */
+export function createFlowStepPathAfterStrippingReviewReturn(
+  step: CreateFlowStep,
+  searchParams: URLSearchParams | null | undefined,
+): string {
+  const params = new URLSearchParams(searchParams?.toString() ?? "");
+  params.delete(CREATE_FLOW_REVIEW_RETURN_QUERY_KEY);
+  const query: CreateFlowPathQuery = {};
+  params.forEach((value, key) => {
+    query[key] = value;
+  });
+  return createFlowStepPath(
+    step,
+    Object.keys(query).length > 0 ? query : undefined,
+  );
+}