datalog: org-chart + transitive headcount demo (219/219)

Adds dl-demo-org-rules: (subordinate Mgr Emp) over a (manager
EMP MGR) graph, and (headcount Mgr N) using count aggregation
grouped by manager. Demonstrates real-world hierarchy queries
(e.g. "everyone reporting up to the CEO") + per-manager rollup.

3 new demo tests: transitive subordinates of CEO (5 entries),
CEO headcount, and direct manager headcount.

lib/datalog/demo.sx

@@ -6,7 +6,7 @@
 ;; below show the shape of queries we want, and the test suite runs
 ;; them against synthetic in-memory tuples loaded via dl-program-data.
 ;;
-;; Six thematic demos:
+;; Seven thematic demos:
 ;;
 ;;   1. Federation — follow graph, transitive reach, mutuals, FOAF.
 ;;   2. Content    — posts, tags, likes, popularity, "for you" feed.
@@ -15,6 +15,7 @@
 ;;                      follow (transitively)" multi-domain query.
 ;;   5. Tag co-occurrence — distinct (T1, T2) pairs with counts.
 ;;   6. Shortest path  — weighted-DAG path enumeration + min agg.
+;;   7. Org chart      — transitive subordinate + headcount per mgr.
 
 ;; ── Demo 1: federation follow graph ─────────────────────────────
 ;; EDB: (follows ACTOR-A ACTOR-B) — A follows B.
@@ -132,6 +133,24 @@
        (is W (+ W1 W2)))
      (shortest X Y W <- (path X Y _) (min W C (path X Y C))))))
 
+;; ── Demo 7: org chart + transitive headcount ───────────────────
+;; Manager graph: each employee has a single manager. Compute the
+;; transitive subordinate set and headcount per manager.
+;;
+;; EDB:
+;;   (manager EMP MGR)            — EMP reports directly to MGR
+;; IDB:
+;;   (subordinate MGR EMP)        — EMP is in MGR's subtree
+;;   (headcount MGR N)            — number of subordinates under MGR
+(define
+  dl-demo-org-rules
+  (quote
+    ((subordinate Mgr Emp <- (manager Emp Mgr))
+     (subordinate Mgr Emp
+       <- (manager Mid Mgr) (subordinate Mid Emp))
+     (headcount Mgr N
+       <- (subordinate Mgr Anyone) (count N E (subordinate Mgr E))))))
+
 ;; ── Loader stub ──────────────────────────────────────────────────
 ;; Wiring to PostgreSQL would replace these helpers with calls into
 ;; rose-ash's internal HTTP RPC (fetch_data → /internal/data/...).

lib/datalog/scoreboard.json

@@ -1,8 +1,8 @@
 {
   "lang": "datalog",
-  "total_passed": 216,
+  "total_passed": 219,
   "total_failed": 0,
-  "total": 216,
+  "total": 219,
   "suites": [
     {"name":"tokenize","passed":26,"failed":0,"total":26},
     {"name":"parse","passed":18,"failed":0,"total":18},
@@ -14,7 +14,7 @@
     {"name":"aggregates","passed":19,"failed":0,"total":19},
     {"name":"api","passed":20,"failed":0,"total":20},
     {"name":"magic","passed":22,"failed":0,"total":22},
-    {"name":"demo","passed":18,"failed":0,"total":18}
+    {"name":"demo","passed":21,"failed":0,"total":21}
   ],
-  "generated": "2026-05-08T10:21:54+00:00"
+  "generated": "2026-05-08T10:23:54+00:00"
 }

lib/datalog/scoreboard.md

@@ -1,6 +1,6 @@
 # datalog scoreboard
 
-**216 / 216 passing** (0 failure(s)).
+**219 / 219 passing** (0 failure(s)).
 
 | Suite | Passed | Total | Status |
 |-------|--------|-------|--------|
@@ -14,4 +14,4 @@
 | aggregates | 19 | 19 | ok |
 | api | 20 | 20 | ok |
 | magic | 22 | 22 | ok |
-| demo | 18 | 18 | ok |
+| demo | 21 | 21 | ok |

lib/datalog/tests/demo.sx

@@ -262,6 +262,42 @@
           (quote (shortest a d W)))
         (list))
 
+      ;; ── Org chart + headcount ─────────────────────────────
+      (dl-demo-test-set! "ceo subordinate transitive"
+        (dl-query
+          (dl-demo-make
+            (quote
+              ((manager ic1 mgr1) (manager ic2 mgr1)
+               (manager mgr1 vp1) (manager ic3 vp1)
+               (manager vp1 ceo)))
+            dl-demo-org-rules)
+          (quote (subordinate ceo X)))
+        (list
+          {:X (quote vp1)} {:X (quote mgr1)} {:X (quote ic1)}
+          {:X (quote ic2)} {:X (quote ic3)}))
+
+      (dl-demo-test-set! "ceo headcount = 5"
+        (dl-query
+          (dl-demo-make
+            (quote
+              ((manager ic1 mgr1) (manager ic2 mgr1)
+               (manager mgr1 vp1) (manager ic3 vp1)
+               (manager vp1 ceo)))
+            dl-demo-org-rules)
+          (quote (headcount ceo N)))
+        (list {:N 5}))
+
+      (dl-demo-test-set! "mgr1 headcount = 2"
+        (dl-query
+          (dl-demo-make
+            (quote
+              ((manager ic1 mgr1) (manager ic2 mgr1)
+               (manager mgr1 vp1) (manager ic3 vp1)
+               (manager vp1 ceo)))
+            dl-demo-org-rules)
+          (quote (headcount mgr1 N)))
+        (list {:N 2}))
+
       (dl-demo-test-set! "no access without grant"
         (dl-query
           (dl-demo-make