OG/db/auth-hook.sql

-- Custom Access Token Hook
-- Implements AD-2 from docs/03-architecture.md:
--   "A Postgres function copies role/org_id into JWT claims (custom
--    access token hook) so RLS can check them cheaply."
--
-- Run this AFTER schema.sql (needs the profiles table to exist).
-- After running, enable the hook in the Supabase dashboard (see bottom
-- of this file for the exact steps) — running the SQL alone does not
-- activate it.

create or replace function public.custom_access_token_hook(event jsonb)
returns jsonb
language plpgsql
stable
as $$
  declare
    claims jsonb;
    user_role public.user_role;
    user_org_id uuid;
  begin
    -- Look up this user's role and org_id from profiles.
    select role, org_id
      into user_role, user_org_id
      from public.profiles
      where id = (event->>'user_id')::uuid;

    claims := event->'claims';

    if user_role is not null then
      claims := jsonb_set(claims, '{role}', to_jsonb(user_role));
      claims := jsonb_set(claims, '{org_id}', to_jsonb(user_org_id));
    else
      claims := jsonb_set(claims, '{role}', 'null');
      claims := jsonb_set(claims, '{org_id}', 'null');
    end if;

    event := jsonb_set(event, '{claims}', claims);

    return event;
  end;
$$;

-- The hook runs as the supabase_auth_admin role, not as the logged-in
-- user, so it needs explicit permission to call the function and read
-- profiles. Everyone else is explicitly blocked from calling it directly.

grant usage on schema public to supabase_auth_admin;

grant execute
  on function public.custom_access_token_hook
  to supabase_auth_admin;

revoke execute
  on function public.custom_access_token_hook
  from authenticated, anon, public;

grant select
  on table public.profiles
  to supabase_auth_admin;

create policy "Allow auth admin to read profiles for JWT hook"
  on public.profiles
  as permissive
  for select
  to supabase_auth_admin
  using (true);

-- ============================================================
-- Dashboard steps to enable this hook (run the SQL above first):
--
-- 1. Supabase dashboard → Authentication → Hooks (left sidebar,
--    under "Configuration").
-- 2. Find "Customize Access Token (JWT) Claims hook".
-- 3. Choose "Postgres function" as the hook type.
-- 4. Select public.custom_access_token_hook from the dropdown.
-- 5. Enable the hook (toggle on) and save.
-- 6. Existing logged-in sessions keep their OLD token until they
--    refresh/re-login — log out and back in to see new claims.
-- ============================================================