diff --git a/supabase/migrations/20260522001000_add_contract_version_to_inbound_webhook_events.sql b/supabase/migrations/20260522001000_add_contract_version_to_inbound_webhook_events.sql
new file mode 100644
index 000000000..6a59bd1dd
--- /dev/null
+++ b/supabase/migrations/20260522001000_add_contract_version_to_inbound_webhook_events.sql
@@ -0,0 +1,31 @@
+-- contracts/05 — adiciona inbound_webhook_events.contract_version
+--
+-- Necessário para o handler `webhook-inbound` migrado em #45 conseguir gravar
+-- a versão de contrato negociada (default '1' para compat).
+--
+-- Risco: baixo. ALTER TABLE com DEFAULT em coluna nova é metadata-only no PG12+.
+-- A coluna recebe '1' automaticamente em todas as linhas existentes via DEFAULT,
+-- sem rewrite da tabela.
+
+BEGIN;
+
+ALTER TABLE public.inbound_webhook_events
+  ADD COLUMN IF NOT EXISTS contract_version text NOT NULL DEFAULT '1';
+
+COMMENT ON COLUMN public.inbound_webhook_events.contract_version IS
+  'Versão de contrato negociada via header accept-version. Default 1 (compat com payloads legados).';
+
+-- Sanity check: deve existir após o ALTER
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.columns
+    WHERE table_schema = 'public'
+      AND table_name = 'inbound_webhook_events'
+      AND column_name = 'contract_version'
+  ) THEN
+    RAISE EXCEPTION 'contracts/05 migration: contract_version column was not created';
+  END IF;
+END $$;
+
+COMMIT;