# Allow Sign-Up Via Environment Variable

Date: 2026-08-19
Status: Draft

## Summary

Replace the current "count of users" check that gates sign-up with a
single environment variable. This lets an operator explicitly control
whether public sign-up is available, instead of Podstalk inferring it
from how many users already exist.

## Motivation

Today `ServeSignup` disables sign-up once a user already exists
(`store.UserCount() > 0`). That is implicit and easy to get wrong: the
first user must register before anyone can log in, and once that happens
no one can ever register again. Controlling this with an explicit
environment variable is predictable and self-documenting.

## Behavior

New environment variable: `PODSTALK_ALLOW_SIGNUP`.

- Unset or any falsy value (`false`, `0`, `no`, `off`): sign-up **disabled**.
- Truthy value (`true`, `1`, `yes`, `on`): sign-up **enabled**.

Default (unset) is **disabled**.

## Changes

### `main.go`

Read `PODSTALK_ALLOW_SIGNUP` from the environment and resolve it with a
truthy-value parser. Set the resulting boolean on the `AuthHandler`.

### `handler/auth.go`

- Add an `AllowSignup bool` field to `AuthHandler`.
- `ServeSignup`: redirect to `/signin` when `!AllowSignup` (replaces the
  `UserCount() > 0` check).
- Replace the `hasUsers()` helper (driven by user count) with a check on
  `AllowSignup`, so the Sign In page shows/ hides the "Sign Up" nav link
  based on whether sign-up is enabled.

### Unchanged

`store.UserCount()` remains in the store package. It is no longer used by
authentication but is left in place as a general utility.

## Out of Scope

- No admin/user-management UI to invite specific users.
- No change to the existing `adduser` CLI command (operator provisioning
  still works regardless of the sign-up toggle).
- No change to sign-in/sign-out behavior.

## Testing

- `scripts/build` passes (gofmt, go vet, go build, docker build).
- Manual verification is limited by the sandbox; behavior relies on the
  straightforward boolean branch and the truthy parser.