mod: Ext 16 — ActivityPub-shaped decision export, 350/350

mod/decision->activity maps a decision to a moderation verb (remove→Delete,
ban→Block, hide/escalate→Flag, keep→no activity) shaped like an AP activity,
preserving the precise action. mod/decisions->activities batch-exports dropping
keeps. With wire (Ext 14) + fed trust (Phase 4) the federated moderation path is
end-to-end: decide → activity/wire → peer → trust-gate → apply. +17 tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/mod/activity.sx

@@ -0,0 +1,40 @@
+;; lib/mod/activity.sx — export decisions as ActivityPub-shaped events.
+;;
+;; The rose-ash platform propagates cross-domain effects as ActivityPub-shaped
+;; activities. A moderation decision maps to a moderation verb so the rest of the
+;; platform (and federated peers) can act on it: remove→Delete, ban→Block,
+;; hide/escalate→Flag, keep→no activity. The precise mod action is preserved in
+;; :action so a consumer can disambiguate (e.g. hide vs escalate, both Flag).
+
+(define
+  mod/action->verb
+  (fn
+    (action)
+    (cond
+      ((= action "remove") "Delete")
+      ((= action "ban") "Block")
+      ((= action "hide") "Flag")
+      ((= action "escalate") "Flag")
+      (true nil))))
+
+(define
+  mod/decision->activity
+  (fn
+    (d actor)
+    (let
+      ((verb (mod/action->verb (get d :action))))
+      (if (nil? verb) nil {:type verb :action (get d :action) :actor actor :summary (str "moderation/" (get d :action) " via " (get d :rule)) :object (get d :report-id) :rule (get d :rule)}))))
+
+;; map a batch of decisions to activities, dropping the no-op keeps
+(define
+  mod/decisions->activities
+  (fn
+    (decisions actor)
+    (reduce
+      (fn
+        (acc d)
+        (let
+          ((a (mod/decision->activity d actor)))
+          (if (nil? a) acc (append acc (list a)))))
+      (list)
+      decisions)))

lib/mod/conformance.conf

@@ -23,6 +23,7 @@ PRELOADS=(
   lib/mod/temporal.sx
   lib/mod/sla.sx
   lib/mod/wire.sx
+  lib/mod/activity.sx
   lib/mod/lifecycle.sx
   lib/mod/audit.sx
   lib/mod/api.sx
@@ -49,4 +50,5 @@ SUITES=(
   "sla:lib/mod/tests/sla.sx:(mod-sla-tests-run!)"
   "wire:lib/mod/tests/wire.sx:(mod-wire-tests-run!)"
   "disjunction:lib/mod/tests/disjunction.sx:(mod-disjunction-tests-run!)"
+  "activity:lib/mod/tests/activity.sx:(mod-activity-tests-run!)"
 )

lib/mod/scoreboard.json

@@ -1,8 +1,8 @@
 {
   "lang": "mod",
-  "total_passed": 333,
+  "total_passed": 350,
   "total_failed": 0,
-  "total": 333,
+  "total": 350,
   "suites": [
     {"name":"decide","passed":31,"failed":0,"total":31},
     {"name":"audit","passed":29,"failed":0,"total":29},
@@ -20,7 +20,8 @@
     {"name":"temporal","passed":15,"failed":0,"total":15},
     {"name":"sla","passed":15,"failed":0,"total":15},
     {"name":"wire","passed":16,"failed":0,"total":16},
-    {"name":"disjunction","passed":10,"failed":0,"total":10}
+    {"name":"disjunction","passed":10,"failed":0,"total":10},
+    {"name":"activity","passed":17,"failed":0,"total":17}
   ],
-  "generated": "2026-06-06T19:22:42+00:00"
+  "generated": "2026-06-06T19:28:13+00:00"
 }

lib/mod/scoreboard.md

@@ -1,6 +1,6 @@
 # mod scoreboard
 
-**333 / 333 passing** (0 failure(s)).
+**350 / 350 passing** (0 failure(s)).
 
 | Suite | Passed | Total | Status |
 |-------|--------|-------|--------|
@@ -21,3 +21,4 @@
 | sla | 15 | 15 | ok |
 | wire | 16 | 16 | ok |
 | disjunction | 10 | 10 | ok |
+| activity | 17 | 17 | ok |

lib/mod/tests/activity.sx

@@ -0,0 +1,95 @@
+;; lib/mod/tests/activity.sx — Ext 16: ActivityPub-shaped decision export.
+
+(define mod-ap-count 0)
+(define mod-ap-pass 0)
+(define mod-ap-fail 0)
+(define mod-ap-failures (list))
+
+(define
+  mod-ap-test!
+  (fn
+    (name got expected)
+    (begin
+      (set! mod-ap-count (+ mod-ap-count 1))
+      (if
+        (= got expected)
+        (set! mod-ap-pass (+ mod-ap-pass 1))
+        (begin
+          (set! mod-ap-fail (+ mod-ap-fail 1))
+          (append!
+            mod-ap-failures
+            (str name "\n    expected: " expected "\n    got:      " got)))))))
+
+;; ── action → AP verb ──
+
+(mod-ap-test! "remove → Delete" (mod/action->verb "remove") "Delete")
+(mod-ap-test! "ban → Block" (mod/action->verb "ban") "Block")
+(mod-ap-test! "hide → Flag" (mod/action->verb "hide") "Flag")
+(mod-ap-test! "escalate → Flag" (mod/action->verb "escalate") "Flag")
+(mod-ap-test! "keep → nil (no activity)" (mod/action->verb "keep") nil)
+
+;; ── single decision → activity ──
+
+(define mod-ap-spam (mod/mk-report "r1" "a" "bob" "this is spam"))
+(define
+  mod-ap-dec
+  (mod/decide-report mod-ap-spam (list mod-ap-spam) mod/default-rules))
+(define mod-ap-act (mod/decision->activity mod-ap-dec "instance.example"))
+
+(mod-ap-test! "activity type is Flag (hide)" (get mod-ap-act :type) "Flag")
+(mod-ap-test! "activity object is report id" (get mod-ap-act :object) "r1")
+(mod-ap-test!
+  "activity actor preserved"
+  (get mod-ap-act :actor)
+  "instance.example")
+(mod-ap-test!
+  "activity preserves precise action"
+  (get mod-ap-act :action)
+  "hide")
+(mod-ap-test! "activity carries rule" (get mod-ap-act :rule) "spam-hide")
+(mod-ap-test!
+  "activity summary"
+  (get mod-ap-act :summary)
+  "moderation/hide via spam-hide")
+
+;; ── keep produces no activity ──
+
+(define mod-ap-clean (mod/mk-report "r2" "a" "b" "a fine post"))
+(define
+  mod-ap-keep
+  (mod/decide-report mod-ap-clean (list mod-ap-clean) mod/default-rules))
+(mod-ap-test!
+  "keep decision → nil activity"
+  (mod/decision->activity mod-ap-keep "x")
+  nil)
+
+;; ── abuse → Delete ──
+
+(define mod-ap-abuse (mod/mk-report "r3" "a" "b" "harassment here"))
+(define
+  mod-ap-abuse-dec
+  (mod/decide-report mod-ap-abuse (list mod-ap-abuse) mod/default-rules))
+(mod-ap-test!
+  "abuse decision → Delete activity"
+  (get (mod/decision->activity mod-ap-abuse-dec "x") :type)
+  "Delete")
+
+;; ── batch export drops keeps ──
+
+(define mod-ap-decisions (list mod-ap-dec mod-ap-keep mod-ap-abuse-dec))
+(define mod-ap-acts (mod/decisions->activities mod-ap-decisions "inst"))
+(mod-ap-test! "batch export drops the keep" (len mod-ap-acts) 2)
+(mod-ap-test!
+  "batch export first is the Flag"
+  (get (first mod-ap-acts) :type)
+  "Flag")
+(mod-ap-test!
+  "batch export second is the Delete"
+  (get (nth mod-ap-acts 1) :type)
+  "Delete")
+(mod-ap-test!
+  "empty decisions → no activities"
+  (mod/decisions->activities (list) "inst")
+  (list))
+
+(define mod-activity-tests-run! (fn () {:failures mod-ap-failures :total mod-ap-count :passed mod-ap-pass :failed mod-ap-fail}))