mod: Ext 11 — batch triage + corpus analytics, 277/277

mod/decide-batch triages a queue; mod/action-histogram summarizes outcomes by
action; mod/rule-coverage + mod/never-fired measure which rules fire across a
corpus — the empirical complement to lint's static unreachable check (lint finds
rules that can't fire; never-fired finds rules that didn't). +17 tests.

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

lib/mod/tests/batch.sx

@@ -0,0 +1,101 @@
+;; lib/mod/tests/batch.sx — Ext 11: batch triage + corpus analytics.
+
+(define mod-b-count 0)
+(define mod-b-pass 0)
+(define mod-b-fail 0)
+(define mod-b-failures (list))
+
+(define
+  mod-b-test!
+  (fn
+    (name got expected)
+    (begin
+      (set! mod-b-count (+ mod-b-count 1))
+      (if
+        (= got expected)
+        (set! mod-b-pass (+ mod-b-pass 1))
+        (begin
+          (set! mod-b-fail (+ mod-b-fail 1))
+          (append!
+            mod-b-failures
+            (str name "\n    expected: " expected "\n    got:      " got)))))))
+
+;; corpus: 2 spam, 1 abuse, 2 clean — distinct subjects so the count rule stays quiet
+(define
+  mod-b-corpus
+  (list
+    (mod/mk-report "r1" "u" "s1" "this is spam")
+    (mod/mk-report "r2" "u" "s2" "buy now offer")
+    (mod/mk-report "r3" "u" "s3" "harassment here")
+    (mod/mk-report "r4" "u" "s4" "a fine post")
+    (mod/mk-report "r5" "u" "s5" "thanks for sharing")))
+
+(define mod-b-decisions (mod/decide-batch mod-b-corpus mod/default-rules))
+
+;; ── decide-batch ──
+
+(mod-b-test! "one decision per report" (len mod-b-decisions) 5)
+(mod-b-test!
+  "first decision is hide"
+  (get (first mod-b-decisions) :action)
+  "hide")
+
+;; ── action histogram ──
+
+(define mod-b-hist (mod/action-histogram mod-b-decisions))
+(mod-b-test! "histogram hide count" (get mod-b-hist :hide) 2)
+(mod-b-test! "histogram remove count" (get mod-b-hist :remove) 1)
+(mod-b-test! "histogram keep count" (get mod-b-hist :keep) 2)
+(mod-b-test! "histogram escalate count" (get mod-b-hist :escalate) 0)
+(mod-b-test! "histogram ban count" (get mod-b-hist :ban) 0)
+(mod-b-test!
+  "histogram totals match corpus"
+  (+
+    (+ (get mod-b-hist :hide) (get mod-b-hist :remove))
+    (+
+      (get mod-b-hist :keep)
+      (+ (get mod-b-hist :escalate) (get mod-b-hist :ban))))
+  5)
+
+;; ── rule coverage (empirical) ──
+
+(define mod-b-cov (mod/rule-coverage mod-b-corpus mod/default-rules))
+(mod-b-test! "coverage has one row per rule" (len mod-b-cov) 6)
+(mod-b-test!
+  "spam-hide fired twice"
+  (mod/rule-fire-count mod-b-decisions "spam-hide")
+  2)
+(mod-b-test!
+  "abuse-remove fired once"
+  (mod/rule-fire-count mod-b-decisions "abuse-remove")
+  1)
+(mod-b-test!
+  "default-keep fired twice"
+  (mod/rule-fire-count mod-b-decisions "default-keep")
+  2)
+
+;; ── never-fired: rules not exercised by this corpus ──
+
+(define mod-b-never (mod/never-fired mod-b-corpus mod/default-rules))
+(mod-b-test!
+  "exonerated-keep never fired"
+  (mod/member? "exonerated-keep" mod-b-never)
+  true)
+(mod-b-test!
+  "reviewer-remove never fired"
+  (mod/member? "reviewer-remove" mod-b-never)
+  true)
+(mod-b-test!
+  "repeated-escalate never fired"
+  (mod/member? "repeated-escalate" mod-b-never)
+  true)
+(mod-b-test!
+  "spam-hide DID fire (not in never-fired)"
+  (mod/member? "spam-hide" mod-b-never)
+  false)
+(mod-b-test!
+  "three rules never fired on this corpus"
+  (len mod-b-never)
+  3)
+
+(define mod-batch-tests-run! (fn () {:failures mod-b-failures :total mod-b-count :passed mod-b-pass :failed mod-b-fail}))