mod: Phase 1 — report schema + policy engine on Prolog, 31/31

Reports → Prolog facts (report/3, classification/2, report_count/2); ordered
policy rules compile to policy_action/3 clauses, first match wins via
pl-query-one. Decisions carry their proof (matching rule + conditions +
evidence). Spam/abuse keyword classification, repeated-report escalation via
Prolog join+arithmetic, no-rule→keep default. Registry api + conformance harness.

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

lib/mod/tests/decide.sx

@@ -0,0 +1,215 @@
+;; lib/mod/tests/decide.sx — Phase 1: report representation + simple policy.
+
+(define mod-dec-count 0)
+(define mod-dec-pass 0)
+(define mod-dec-fail 0)
+(define mod-dec-failures (list))
+
+(define
+  mod-dec-test!
+  (fn
+    (name got expected)
+    (begin
+      (set! mod-dec-count (+ mod-dec-count 1))
+      (if
+        (= got expected)
+        (set! mod-dec-pass (+ mod-dec-pass 1))
+        (begin
+          (set! mod-dec-fail (+ mod-dec-fail 1))
+          (append!
+            mod-dec-failures
+            (str name "\n    expected: " expected "\n    got:      " got)))))))
+
+;; decide a single report (count over a 1-element registry)
+(define
+  mod-dec-one
+  (fn
+    (reason)
+    (let
+      ((r (mod/mk-report "r1" "alice" "bob" reason)))
+      (mod/decide-report r (list r) mod/default-rules))))
+
+(define mod-dec-action (fn (reason) (get (mod-dec-one reason) :action)))
+
+;; ── spam keyword → :hide ──
+
+(mod-dec-test!
+  "spam keyword 'spam' → hide"
+  (mod-dec-action "this is spam")
+  "hide")
+(mod-dec-test!
+  "spam keyword 'buy now' → hide"
+  (mod-dec-action "buy now while stocks last")
+  "hide")
+(mod-dec-test!
+  "spam keyword case-insensitive 'CLICK HERE' → hide"
+  (mod-dec-action "CLICK HERE now")
+  "hide")
+(mod-dec-test!
+  "spam keyword 'free money' → hide"
+  (mod-dec-action "win free money fast")
+  "hide")
+
+;; ── abuse keyword → :remove ──
+
+(mod-dec-test!
+  "abuse keyword 'harassment' → remove"
+  (mod-dec-action "ongoing harassment of users")
+  "remove")
+(mod-dec-test!
+  "abuse keyword 'threat' → remove"
+  (mod-dec-action "this is a threat")
+  "remove")
+(mod-dec-test!
+  "abuse keyword 'slur' → remove"
+  (mod-dec-action "contains a slur")
+  "remove")
+
+;; ── no rule → :keep ──
+
+(mod-dec-test!
+  "neutral reason → keep"
+  (mod-dec-action "I disagree with this post")
+  "keep")
+(mod-dec-test! "empty reason → keep" (mod-dec-action "") "keep")
+
+;; ── decision carries the matching rule (proof, not bare keyword) ──
+
+(mod-dec-test!
+  "spam decision rule name"
+  (get (mod-dec-one "this is spam") :rule)
+  "spam-hide")
+(mod-dec-test!
+  "keep decision rule name"
+  (get (mod-dec-one "fine post") :rule)
+  "default-keep")
+(mod-dec-test!
+  "abuse decision rule name"
+  (get (mod-dec-one "harassment here") :rule)
+  "abuse-remove")
+(mod-dec-test!
+  "spam proof :rule"
+  (get (get (mod-dec-one "spam!") :proof) :rule)
+  "spam-hide")
+(mod-dec-test!
+  "spam proof :evidence"
+  (get (get (mod-dec-one "spam!") :proof) :evidence)
+  (list "spam"))
+(mod-dec-test!
+  "spam proof :count"
+  (get (get (mod-dec-one "spam!") :proof) :count)
+  1)
+
+;; ── classification (evidence derivation) ──
+
+(mod-dec-test!
+  "classify spam"
+  (mod/classify-keywords (mod/mk-report "r1" "a" "b" "spam!"))
+  (list "spam"))
+(mod-dec-test!
+  "classify abuse"
+  (mod/classify-keywords (mod/mk-report "r1" "a" "b" "abuse"))
+  (list "abuse"))
+(mod-dec-test!
+  "classify neutral → empty"
+  (mod/classify-keywords (mod/mk-report "r1" "a" "b" "hello"))
+  (list))
+(mod-dec-test!
+  "classify both spam+abuse"
+  (mod/classify-keywords (mod/mk-report "r1" "a" "b" "spam and abuse"))
+  (list "spam" "abuse"))
+
+;; ── report-count + repeated → :escalate ──
+
+(define
+  mod-dec-three
+  (list
+    (mod/mk-report "r1" "a" "bob" "x")
+    (mod/mk-report "r2" "c" "bob" "y")
+    (mod/mk-report "r3" "d" "bob" "z")))
+
+(mod-dec-test!
+  "report-count counts subject"
+  (mod/report-count "bob" mod-dec-three)
+  3)
+(mod-dec-test!
+  "3 reports about subject → escalate"
+  (get
+    (mod/decide-report (first mod-dec-three) mod-dec-three mod/default-rules)
+    :action)
+  "escalate")
+(mod-dec-test!
+  "escalate rule name"
+  (get
+    (mod/decide-report (first mod-dec-three) mod-dec-three mod/default-rules)
+    :rule)
+  "repeated-escalate")
+
+(define
+  mod-dec-two
+  (list
+    (mod/mk-report "r1" "a" "carol" "x")
+    (mod/mk-report "r2" "c" "carol" "y")))
+
+(mod-dec-test!
+  "2 reports about subject → keep (below threshold)"
+  (get
+    (mod/decide-report (first mod-dec-two) mod-dec-two mod/default-rules)
+    :action)
+  "keep")
+
+;; ── precedence: spam beats repeated ──
+
+(define
+  mod-dec-spam-among-many
+  (list
+    (mod/mk-report "r1" "a" "dave" "buy now spam")
+    (mod/mk-report "r2" "c" "dave" "y")
+    (mod/mk-report "r3" "d" "dave" "z")))
+
+(mod-dec-test!
+  "spam wins over repeated (precedence)"
+  (get
+    (mod/decide-report
+      (first mod-dec-spam-among-many)
+      mod-dec-spam-among-many
+      mod/default-rules)
+    :action)
+  "hide")
+
+;; ── accessors ──
+
+(mod-dec-test!
+  "report-about accessor"
+  (mod/report-about (mod/mk-report "r1" "a" "bob" "x"))
+  "bob")
+(mod-dec-test!
+  "report-by accessor"
+  (mod/report-by (mod/mk-report "r1" "alice" "bob" "x"))
+  "alice")
+
+;; ── api registry ──
+
+(mod/reset!)
+(define mod-dec-r1 (mod/report "alice" "bob" "this is spam"))
+(define mod-dec-r2 (mod/report "carol" "eve" "fine post"))
+
+(mod-dec-test!
+  "mod/report assigns sequential id r1"
+  (mod/report-id mod-dec-r1)
+  "r1")
+(mod-dec-test!
+  "mod/report assigns sequential id r2"
+  (mod/report-id mod-dec-r2)
+  "r2")
+(mod-dec-test!
+  "mod/decide via registry → hide"
+  (get (mod/decide "r1") :action)
+  "hide")
+(mod-dec-test!
+  "mod/decide via registry → keep"
+  (get (mod/decide "r2") :action)
+  "keep")
+(mod-dec-test! "mod/decide unknown id → nil" (mod/decide "r99") nil)
+
+(define mod-decide-tests-run! (fn () {:failures mod-dec-failures :total mod-dec-count :passed mod-dec-pass :failed mod-dec-fail}))