POC

c/tskit/tables.h

@@ -158,6 +158,10 @@ typedef struct {
     /** @brief The ID of the edge that this mutation lies on, or TSK_NULL
       if there is no corresponding edge.*/
     tsk_id_t edge;
+    /** @brief Inherited state. */
+    const char *inherited_state;
+    /** @brief Size of the inherited state in bytes. */
+    tsk_size_t inherited_state_length;
 } tsk_mutation_t;
 
 /**

c/tskit/trees.c

@@ -4951,6 +4951,8 @@ tsk_treeseq_get_mutation(
         goto out;
     }
     mutation->edge = self->site_mutations_mem[index].edge;
+    mutation->inherited_state = self->site_mutations_mem[index].inherited_state;
+    mutation->inherited_state_length = self->site_mutations_mem[index].inherited_state_length;
 out:
     return ret;
 }