# User input and MFA

`ctx.input` pauses execution and lets Link display a form. Submitting resumes the same run.

## Request a code

Inside a flow's `exec(ctx)`:

```ts
const { code } = await ctx.input("verification", {
  purpose: "operation",
  schema: z.object({ code: z.string().regex(/^\d{6}$/) }),
  fields: { code: { label: "Verification code", type: "text" } },
  message: "Enter the code sent by the website to confirm cancellation.",
});
```

Import `z` from `zod`. Use `code` in the next durable step to submit the actual website form.

| Purpose      | Example                   | App behavior                             |
| ------------ | ------------------------- | ---------------------------------------- |
| `connection` | Expired login needs MFA   | Ask the account holder to restore access |
| `operation`  | Cancellation confirmation | Ask the user to confirm this operation   |

Authentication flows default to connection purpose. Other flows default to operation purpose.

![Hosted Link waits for a verification code from the account holder.](/docs/hosted-mfa.png)

## Rejected input

Inside `exec(ctx)`, call your website's verification helper from a durable step:

```ts
for (let attempt = 0; attempt < 3; attempt++) {
  const { code } = await ctx.input("verification", {
    purpose: "operation",
    schema: z.object({ code: z.string().min(1) }),
    fields: { code: { label: "Verification code", type: "text" } },
    ...(attempt
      ? {
          feedback: {
            tone: "error" as const,
            message: "Incorrect code. Try again.",
          },
        }
      : {}),
  });
  const accepted = await ctx.step("verify", () => submitCode(ctx, code));
  if (accepted) return { verified: true };
}
throw new FlowError("VERIFICATION_REJECTED", "Verification attempts exhausted");
```

`submitCode(ctx, code)` is your website helper: submit the real form and return whether the website accepted it. Import `FlowError` from the SDK and use a matching output schema for your flow.

Each request is a new occurrence; a previous code is not reused. Supported field types are `text`, `email` and `password`; schemas describe flat string fields.

## Foreground and background

| Run                  | What happens when it needs input                     |
| -------------------- | ---------------------------------------------------- |
| User-driven endpoint | Open hosted Link for the waiting run                 |
| Scheduled sync       | Send `run.requires_input`; let the user return later |
| Sync already waiting | No overlapping scheduled occurrence is created       |

**Next:** [Resume a waiting run from your app](/docs/connect#resume-an-existing-run).