mod: Ext 7 — repeat-offender escalation (audit log as evidence), 223/223

mod/subject-sanctions counts prior hide/remove/ban decisions about a subject from
the append-only audit log; mod/decide-escalating upgrades a sanction to :ban when
the subject has >= k priors. Non-sanction outcomes (keep/escalate) pass through.
Closes the loop between audit and policy — the trail feeds future decisions. Own
suite. +19 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` → **204/204** (roadmap + 6 extensions complete)
+`bash lib/mod/conformance.sh` → **223/223** (roadmap + 7 extensions complete)
 
 ## Ground rules
 
@@ -147,6 +147,13 @@ 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 7 — repeat-offender escalation** (`lib/mod/offenders.sx`, +19). The
+  audit log as evidence: `mod/subject-sanctions` counts prior hide/remove/ban
+  decisions about a subject; `mod/decide-escalating id k` decides normally then
+  upgrades a *sanction* to `:ban` when the subject already has ≥k prior sanctions.
+  Non-sanction outcomes (keep/escalate) pass through untouched. First decision
+  whose input spans history beyond the single report — read from the trail, not
+  re-derived.
 - [x] **Ext 6 — strictest-wins strategy** (`lib/mod/severity.sx`, +14). Alternative
   to first-match: `mod/decide-strictest` collects every proven rule (`pl-query-all`)
   and picks the highest-`mod/action-severity` action (keep<escalate<hide<remove<ban).
@@ -165,6 +172,12 @@ lib/mod/fed.sx
 
 ## Progress log
 
+- **Ext 7 — repeat-offender escalation, 223/223** (+19). Decisions can now depend
+  on history: the append-only audit log is read back as evidence, and a subject
+  with k prior sanctions has its next sanction upgraded to `:ban`. Closes the loop
+  between audit (Phase 2) and policy — the trail isn't just a record, it feeds
+  future decisions. Non-sanction outcomes never escalate (verified: a clean post
+  that the count rule escalates stays `:escalate`, never `:ban`).
 - **Ext 6 — strictest-wins strategy, 204/204** (+14). A second decision strategy
   alongside first-match: collect all proven rules and apply the harshest sanction.
   Shows the substrate supports more than one precedence policy over the same rule