diff --git a/frontend/src/lib/api.ts b/frontend/src/lib/api.ts
index ac78629..b6afbf8 100644
--- a/frontend/src/lib/api.ts
+++ b/frontend/src/lib/api.ts
@@ -32,22 +32,87 @@ export interface DataResponse {
   rows: DataRow[];
 }
 
+interface FetchOptions {
+  params?: Record<string, string>;
+  method?: string;
+  body?: unknown;
+  okStatuses?: number[];
+}
+
+async function extractDetail(res: Response): Promise<string | null> {
+  try {
+    const body: unknown = await res.json();
+    if (
+      typeof body === "object" &&
+      body !== null &&
+      "detail" in body &&
+      typeof body.detail === "string"
+    ) {
+      return body.detail;
+    }
+  } catch {
+    // non-json error body
+  }
+  return null;
+}
+
 async function apiFetch<T>(
   path: string,
-  params?: Record<string, string>,
-  okStatuses: number[] = [200],
+  options: FetchOptions = {},
 ): Promise<T> {
+  const { params, method = "GET", body, okStatuses = [200] } = options;
   const query = params ? `?${new URLSearchParams(params)}` : "";
   const key = getApiKey();
+  const headers: Record<string, string> = {};
+  if (key) headers.Authorization = `Bearer ${key}`;
+  if (body !== undefined) headers["Content-Type"] = "application/json";
+
   const res = await fetch(`${BASE}${path}${query}`, {
-    headers: key ? { Authorization: `Bearer ${key}` } : {},
+    method,
+    headers,
+    body: body !== undefined ? JSON.stringify(body) : undefined,
   });
   if (!okStatuses.includes(res.status)) {
-    throw new ApiError(res.status, `request to ${path} failed: ${res.status}`);
+    const detail = await extractDetail(res);
+    throw new ApiError(
+      res.status,
+      detail ?? `request to ${path} failed: ${res.status}`,
+    );
   }
   return res.json() as Promise<T>;
 }
 
+export interface ProposedDependency {
+  name: string;
+  version: string;
+  lookback?: string;
+}
+
+export interface DatasetProposalPayload {
+  name: string;
+  version: string;
+  calendar: string;
+  granularity: string;
+  start_date: string;
+  schema: Record<string, string>;
+  dependencies: ProposedDependency[];
+  builder_script: string;
+  author_name: string;
+  team: string;
+  discord_user: string;
+  description: string;
+  env_vars: boolean;
+  requirements_txt?: string;
+  env_template?: string;
+}
+
+export interface ProposalResponse {
+  dataset_name: string;
+  dataset_version: string;
+  pr_url: string;
+  branch: string;
+}
+
 export async function fetchDatasets(): Promise<DatasetSummary[]> {
   const body = await apiFetch<{ datasets: DatasetSummary[] }>("/datasets");
   return body.datasets;
@@ -62,7 +127,20 @@ export function fetchData(
 ): Promise<DataResponse> {
   return apiFetch<DataResponse>(
     `/data/${encodeURIComponent(name)}/${encodeURIComponent(version)}`,
-    { start, end, "build-data": "false" },
-    [200, 206],
+    {
+      params: { start, end, "build-data": "false" },
+      okStatuses: [200, 206],
+    },
   );
 }
+
+// nothing is written to the server: the backend validates the submission and
+// opens a github pr; the dataset goes live after review + merge + restart
+export function proposeDataset(
+  payload: DatasetProposalPayload,
+): Promise<ProposalResponse> {
+  return apiFetch<ProposalResponse>("/datasets", {
+    method: "POST",
+    body: payload,
+  });
+}
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index 981014d..dd953ed 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -1,4 +1,5 @@
 import {
+  MutationCache,
   QueryCache,
   QueryClient,
   QueryClientProvider,
@@ -14,15 +15,16 @@ import { ApiError } from "@/lib/api";
 
 import "@/index.css";
 
+function handleAuthError(error: unknown) {
+  if (error instanceof ApiError && error.status === 401) {
+    toast.error("invalid or missing API key");
+    requestApiKey();
+  }
+}
+
 const queryClient = new QueryClient({
-  queryCache: new QueryCache({
-    onError: (error) => {
-      if (error instanceof ApiError && error.status === 401) {
-        toast.error("invalid or missing API key");
-        requestApiKey();
-      }
-    },
-  }),
+  queryCache: new QueryCache({ onError: handleAuthError }),
+  mutationCache: new MutationCache({ onError: handleAuthError }),
   defaultOptions: {
     queries: {
       // client errors won't fix themselves on retry