mod: Ext 17 — per-domain policy registry, 364/364

mod/register-policy! domain rules + mod/decide-in domain r reports give each
rose-ash domain its own rule set; unregistered domains fall back to default-rules
(never unmoderated). Same spam report → remove under a strict market policy, hide
under blog default. Engine already took rules as a param, so this is registry +
fallback, no engine change. +14 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` → **350/350** (roadmap + 16 extensions complete)
+`bash lib/mod/conformance.sh` → **364/364** (roadmap + 17 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 17 — per-domain policy registry** (`lib/mod/policies.sx`, +14).
+  `mod/register-policy! domain rules` + `mod/decide-in domain r reports` give each
+  rose-ash domain (blog/market/events/…) its own rule set; unregistered domains
+  fall back to default-rules so a new domain is never unmoderated. Same spam report
+  → :remove under a strict market policy, :hide under blog's default.
 - [x] **Ext 16 — ActivityPub-shaped export** (`lib/mod/activity.sx`, +17).
   `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
@@ -224,6 +229,11 @@ lib/mod/fed.sx
 
 ## Progress log
 
+- **Ext 17 — per-domain policy registry, 364/364** (+14). Multi-tenant policy:
+  the engine already took `rules` as a parameter, so domain-scoping is just a
+  registry + a default fallback — no engine change. Makes the whole policy
+  vocabulary (16 prior features) per-domain configurable. Default fallback means
+  adding a domain can't accidentally leave it unmoderated.
 - **Ext 16 — ActivityPub-shaped export, 350/350** (+17). Bridges mod-sx to the
   wider rose-ash platform, which propagates cross-domain effects as AP-shaped
   activities. Decisions become Flag/Delete/Block activities (keep = no-op); with