# TanStack Start

> Isomorphic loaders are the wrong place for a database handle.

<Tabs labels="pnpm, npm, bun">

<Tab>

```sh
pnpm add @usegraft/sdk-tanstack-start @usegraft/auth @usegraft/mcp
```

</Tab>

<Tab>

```sh
npm i @usegraft/sdk-tanstack-start @usegraft/auth @usegraft/mcp
```

</Tab>

<Tab>

```sh
bun add @usegraft/sdk-tanstack-start @usegraft/auth @usegraft/mcp
```

</Tab>

</Tabs>

Build the handle once in a server-only module, then reach it from server
functions and server routes.

## Create the handle

```ts
// src/lib/graft.server.ts
import { createDb } from "@usegraft/db";
import { createGraft } from "@usegraft/sdk-tanstack-start";
import { collections } from "../../graft.config";

export const db = createDb(process.env.DATABASE_URL!).db;
export const graft = createGraft({ db, collections });
```

Static index instead of Postgres:

```ts
import { openStaticIndex } from "@usegraft/db";

export const graft = createGraft({
  index: await openStaticIndex(".graft/index.db"),
  collections,
});
```

## Read one document

```ts
// src/routes/docs.$slug.tsx
import { createServerFn } from "@tanstack/react-start";
import { graft } from "../lib/graft.server";

const getDoc = createServerFn({ method: "GET" })
  .validator((slug: string) => slug)
  .handler(({ data: slug }) => graft.getContent("docs", slug));
```

There is no request-level memo. Reads go straight to the index; call sites own
memoization.

## Mount functions and MCP

Copy these mounts as written. The server-route factory name has moved across
TanStack Start releases; the handler signature has not.

```ts
// src/routes/api/fn/$name.ts
import { createServerFileRoute } from "@tanstack/react-start/server";
import { createFunctionsHandler } from "@usegraft/core";
import { graftRoute } from "@usegraft/sdk-tanstack-start";
import { functions } from "../../../graft.config";
import { db } from "../../lib/graft.server";

const handler = createFunctionsHandler({ db, functions });

export const ServerRoute = createServerFileRoute("/api/fn/$name").methods({
  POST: graftRoute(handler),
  GET: graftRoute(handler), // 405s with Allow and a fix
});
```

```ts
// src/routes/api/mcp.ts
import { createActorResolver } from "@usegraft/auth";
import { createServerFileRoute } from "@tanstack/react-start/server";
import { createGraftMcpHandler } from "@usegraft/mcp";
import { graftRoute } from "@usegraft/sdk-tanstack-start";
import { collections, functions } from "../../graft.config";
import { db } from "../lib/graft.server";

const actor = createActorResolver({
  issuers: (process.env.GRAFT_TRUSTED_ISSUERS ?? "")
    .split(/[,\s]+/)
    .filter(Boolean)
    .map((issuer) => ({ issuer })),
  devTokens: process.env.GRAFT_DEV_TOKEN
    ? {
        [process.env.GRAFT_DEV_TOKEN]: {
          kind: "human",
          id: "owner",
          scopes: ["content:write"],
        },
      }
    : undefined,
});

export const ServerRoute = createServerFileRoute("/api/mcp").methods({
  POST: graftRoute(
    createGraftMcpHandler({
      contentDir: "./content",
      db,
      collections,
      functions,
      actor,
    }),
  ),
});
```

This endpoint serves content writes and asset uploads. JWT verification runs
only when `issuers` is passed; the library does not read
`GRAFT_TRUSTED_ISSUERS` (`graft serve` does). See [Auth](/docs/auth).
Unauthenticated callers get 401. `allowAnonymous: true` is only for a
loopback local server — never on anything reachable from a network. A public
docs surface is [`createDocsMcpHandler`](/docs/docs-mcp), which has no write
tools and no anonymous opt-in.

The parameter is typed structurally as `{ request: Request }`, so this package
needs no `@tanstack/react-start` dependency.

## Cache and invalidation

TanStack Start has no tag-based data cache. Stamp `tagsFor(...)` into a CDN
surrogate-key header on the responses you serve, and purge
`tagsForChanges(branch, changeSet)` from your compile webhook.

```ts
import { tagsFor } from "@usegraft/sdk-tanstack-start";

const slug = "home";
headers.set("Cache-Tag", tagsFor("main", "pages", slug).join(","));
```

`Cache-Tag` is the surrogate-key header. Purge the same strings
`tagsForChanges` returns from your compile webhook.

## The caveat you cannot infer

A route `loader` is the wrong place for this handle. TanStack Start loaders
are **isomorphic**: they run on the server for the first paint and in the
browser on client-side navigation. A handle that holds a database connection
has no business in either the client bundle or the browser, which is what
`createServerFn` is for.

See [SDK reference](/docs/sdk-reference) for mounts across adapters and the
honest gaps.