Index: db-scripts/triggers/finance_validate_trigger.sql
===================================================================
--- db-scripts/triggers/finance_validate_trigger.sql	(revision 42da64dc0d28f9380336816f6fb82c7572d0021d)
+++ db-scripts/triggers/finance_validate_trigger.sql	(revision 42da64dc0d28f9380336816f6fb82c7572d0021d)
@@ -0,0 +1,48 @@
+-- Validate finance percentages on insert/update
+-- Ensures the five budget fields sum to ~100 (tolerance 0.01) and each is between 0 and 100
+-- Schema: trekr
+
+CREATE OR REPLACE FUNCTION trekr.fn_validate_finance_percentages()
+RETURNS trigger
+LANGUAGE plpgsql
+AS $$
+DECLARE
+    s NUMERIC;
+    eps CONSTANT NUMERIC := 0.01; -- allow small rounding differences
+    vals NUMERIC[] := ARRAY[NEW.spending_budget, NEW.saving_budget, NEW.investing_budget, NEW.donation_budget, NEW.credit];
+    v NUMERIC;
+BEGIN
+    -- Null checks: all five values must be provided (business rule)
+    FOREACH v IN ARRAY vals LOOP
+        IF v IS NULL THEN
+            RAISE EXCEPTION 'All 5 finance percentage values are required';
+        END IF;
+        IF v < 0 OR v > 100 THEN
+            RAISE EXCEPTION 'Finance percentage values must be between 0 and 100';
+        END IF;
+    END LOOP;
+
+    s := (NEW.spending_budget + NEW.saving_budget + NEW.investing_budget + NEW.donation_budget + NEW.credit)::numeric;
+    IF abs(s - 100) > eps THEN
+        RAISE EXCEPTION 'Finance percentages must sum to 100 (got: %)', s;
+    END IF;
+
+    RETURN NEW;
+END;
+$$;
+
+-- Trigger on finance_users table
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_trigger t
+        JOIN pg_class c ON t.tgrelid = c.oid
+        WHERE t.tgname = 'trg_validate_finance_percentages' AND c.relname = 'finance_users'
+    ) THEN
+        CREATE TRIGGER trg_validate_finance_percentages
+        BEFORE INSERT OR UPDATE ON trekr.finance_users
+        FOR EACH ROW
+        EXECUTE FUNCTION trekr.fn_validate_finance_percentages();
+    END IF;
+END$$;
+