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>

plans/mod-on-sx.md

@@ -16,7 +16,7 @@ federation extension.
 
 ## Status (rolling)
 
-`bash lib/mod/conformance.sh` → **260/260** (roadmap + 10 extensions complete)
+`bash lib/mod/conformance.sh` → **277/277** (roadmap + 11 extensions complete)
 
 ## Ground rules
 
@@ -147,6 +147,11 @@ lib/mod/fed.sx
   derivation goal-by-goal with `[proved]`/`[unproved]` marks and unification
   bindings. E.g. `Report rc: escalate (rule: repeated-escalate)` … `[proved]
   report(rc, B, S), report_count(S, N), N >= 3  {B=ann, N=3, S=dave}`.
+- [x] **Ext 11 — batch triage + corpus analytics** (`lib/mod/batch.sx`, +17).
+  `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 (Ext 5):
+  lint finds rules that can't fire, never-fired finds rules that didn't.
 - [x] **Ext 10 — policy what-if / impact** (`lib/mod/whatif.sx`, +13).
   `mod/decision-diff` compares one report's action under two rule sets;
   `mod/policy-impact` runs a batch and returns only the reports whose decision
@@ -191,6 +196,11 @@ lib/mod/fed.sx
 
 ## Progress log
 
+- **Ext 11 — batch triage + corpus analytics, 277/277** (+17). Operational layer:
+  triage a queue, histogram the outcomes, and measure rule coverage over real
+  data. `never-fired` pairs with lint (Ext 5) — static "can't fire" vs empirical
+  "didn't fire" — giving policy authors both views of dead rules. Histogram avoids
+  dict mutation by counting over a fixed action vocabulary.
 - **Ext 10 — policy what-if / impact, 260/260** (+13). Decisions are now
   comparable across rule sets — diff one report, or batch a whole set and surface
   only the flips. Pure SX over `decide-report`, no engine change. Closes the