diff --git a/backend/migrations/019_exercises_optional_fields.sql b/backend/migrations/019_exercises_optional_fields.sql
new file mode 100644
index 0000000..b8ccb62
--- /dev/null
+++ b/backend/migrations/019_exercises_optional_fields.sql
@@ -0,0 +1,11 @@
+-- Migration 019: Make exercise goal and execution optional
+-- Many wiki exercises have only goal OR execution, not both
+
+ALTER TABLE exercises
+    ALTER COLUMN goal DROP NOT NULL,
+    ALTER COLUMN execution DROP NOT NULL;
+
+-- Add CHECK constraint: at least one of goal/execution must be present
+ALTER TABLE exercises
+    ADD CONSTRAINT exercises_goal_or_execution_required
+    CHECK (goal IS NOT NULL OR execution IS NOT NULL);