feat: KitchenStock light UI, Gemma 31B AI, supermarket store filters & 130+ vegan products

supabase/migrations/00004_rate_limit_rpc.sql

@@ -0,0 +1,48 @@
+-- Migration 00004: Rate Limiting Function
+
+CREATE OR REPLACE FUNCTION public.check_rate_limit(
+    p_action TEXT,
+    p_max_requests INT,
+    p_window_seconds INT
+)
+RETURNS BOOLEAN
+LANGUAGE plpgsql
+SECURITY DEFINER
+SET search_path = public
+AS $$
+DECLARE
+    v_user_id UUID;
+    v_count INT;
+    v_window_start TIMESTAMPTZ;
+BEGIN
+    v_user_id := auth.uid();
+    IF v_user_id IS NULL THEN
+        RAISE EXCEPTION 'UNAUTHORIZED: User must be authenticated to check rate limit';
+    END IF;
+
+    v_window_start := NOW() - (p_window_seconds || ' seconds')::INTERVAL;
+
+    -- Clean up old events for this user/action
+    DELETE FROM public.rate_limit_events
+    WHERE user_id = v_user_id
+      AND action = p_action
+      AND created_at < v_window_start;
+
+    -- Count requests in current window
+    SELECT COUNT(*) INTO v_count
+    FROM public.rate_limit_events
+    WHERE user_id = v_user_id
+      AND action = p_action
+      AND created_at >= v_window_start;
+
+    IF v_count >= p_max_requests THEN
+        RETURN FALSE;
+    END IF;
+
+    -- Record request
+    INSERT INTO public.rate_limit_events (user_id, action)
+    VALUES (v_user_id, p_action);
+
+    RETURN TRUE;
+END;
+$$;