tests: close remaining contract gaps (action-dispatch, org-headline-add/find-by-id, tangle-sync, create-note, messaging-link/unlink)

org/programming-org.org

@@ -15,7 +15,7 @@ Structural manipulation tools for Org-mode files. This skill handles reading, wr
 4. (org-todo-set ast target-id status): sets TODO status via
    org-property-set.
 5. (org-headline-add ast parent-id title): adds a new child headline.
-6. (org-find-headline-by-id ast id): returns the subtree for a matching
+6. (org-headline-find-by-id ast id): returns the subtree for a matching
    headline ID.
 
 * Implementation
@@ -390,4 +390,24 @@ Verification of the structural manipulation for Org-mode files and their AST rep
                   :contents nil)))
     (org-todo-set ast "id:todo001" "DONE")
     (is (string= (getf (getf ast :properties) :TODO) "DONE"))))
+
+(test test-org-headline-add
+  "Contract 5: org-headline-add inserts a child headline."
+  (let* ((ast (list :type :HEADLINE
+                   :properties (list :ID "root" :TITLE "Root")
+                   :contents nil)))
+    (is (eq t (org-headline-add ast "root" "New Child")))
+    (is (= 1 (length (getf ast :contents))))
+    (is (string= "New Child" (getf (getf (first (getf ast :contents)) :properties) :TITLE)))))
+
+(test test-org-headline-find-by-id
+  "Contract 6: org-headline-find-by-id finds a headline by ID."
+  (let ((ast (list :type :HEADLINE :properties (list :ID "root" :TITLE "Root")
+                   :contents (list (list :type :HEADLINE :properties (list :ID "child1" :TITLE "Child"))
+                                  (list :type :HEADLINE :properties (list :ID "child2" :TITLE "Child 2")))))))
+    (let ((found (org-headline-find-by-id ast "child2")))
+      (is (not (null found)))
+      (is (string= "Child 2" (getf (getf found :properties) :TITLE))))
+    (let ((missing (org-headline-find-by-id ast "nonexistent")))
+      (is (null missing) "Missing ID should return nil"))))
 #+end_src