fix(invitations): a token could never be generated — pgcrypto is in another schema

supabase/migrations/20260828140000_invitation_token_cannot_find_pgcrypto.sql

@@ -0,0 +1,36 @@
+-- Generating an invitation token raises, because it looks for pgcrypto in the
+-- wrong schema.
+--
+-- `generate_invitation_token()` calls `gen_random_bytes(24)` unqualified and
+-- declares no search_path, so the name resolves against whatever the CALLER
+-- has. pgcrypto is installed in `extensions`, not `public` — which is the
+-- normal Supabase layout — and PostgREST calls with `public` on the path. So
+-- the function raises `function gen_random_bytes(integer) does not exist` every
+-- time, and no invitation token has ever been generated.
+--
+-- Same family as the timeline functions repaired in 20260828110000: a
+-- reference that is only resolved at call time, so it looks correct until
+-- somebody uses it. Found by the plpgsql_check gate added alongside them, which
+-- is the first thing that has ever been able to see this class.
+--
+-- Two changes, and the first is the fix:
+--
+--   * qualify the call as `extensions.gen_random_bytes`, so it resolves by
+--     name rather than by whoever happens to be calling;
+--   * pin `search_path`, which this function did not set at all. An unpinned
+--     search_path on a function is also how a caller can shadow a name it
+--     resolves — worth closing on a function whose whole job is minting a
+--     credential.
+--
+-- Deliberately NOT moving pgcrypto into public: extensions belong in their own
+-- schema, and every other caller already reaches them there.
+
+CREATE OR REPLACE FUNCTION public.generate_invitation_token()
+RETURNS text
+LANGUAGE plpgsql
+SET search_path TO 'public', 'extensions'
+AS $function$
+BEGIN
+  RETURN encode(extensions.gen_random_bytes(24), 'base64');
+END;
+$function$;