Scaffolding for the upcoming WhatsApp Flows feature. The whole Flows
stack (interactive button/list send + parse, server-side runner, no-
code builder, templates) will land across the next ~4 PRs *behind*
this gate so the owner can dogfood the feature on their own account
before exposing it to teammates or downstream pullers of the OSS.
What this lands:
1. `profiles.beta_features TEXT[] NOT NULL DEFAULT ARRAY[]::TEXT[]`
— generic opt-in column, lives on the existing profiles table.
Empty by default for every existing row.
2. `src/lib/flows/feature-flag.ts` — `isFlowsEnabled(profile)`
predicate + `BETA_FEATURE_FLOWS` constant. Single source of
truth for the gate; later PRs import this in every guarded
surface (sidebar nav, /flows page, /api/flows routes, webhook
dispatcher).
3. `Profile.beta_features` added to the shared TS type and the
auth hook's local copy. Auth hook loads the column and
defaults it to `[]` defensively if the DB read returns null.
4. 11 unit tests covering null/undefined/empty/mismatched cases,
including case sensitivity (only lowercase `'flows'` opts in)
and defensive guards against malformed input.
How the owner enables it for their own account, once merged:
UPDATE profiles
SET beta_features = array_append(beta_features, 'flows')
WHERE user_id = '<their-auth-uid>';
How we ship it to everyone, when ready: grep-and-delete the
`isFlowsEnabled()` callsites in one cleanup PR.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
