feed: verb-aware smart dedupe — reactions collapse cross-actor, posts stay per-actor + 9 tests

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

plans/feed-on-sx.md

@@ -14,7 +14,7 @@ APL, ACL visibility filtering via `lib/acl/`, federation via fed-sx.
 
 ## Status (rolling)
 
-`bash lib/feed/conformance.sh` → **134/134** (Phases 1–4 + TF-IDF + notifications + home)
+`bash lib/feed/conformance.sh` → **143/143** (Phases 1–4 + TF-IDF + notifications + home + smart-dedupe)
 
 ## Ground rules
 
@@ -147,6 +147,10 @@ are function parameters. Real acl-sx / fed-sx wire in at the call site unchanged
 - [x] **Capstone** `feed/home` — the whole pipeline as one line: fanout ∘ inbox ∘
   dedupe ∘ ACL ∘ rank ∘ take (`home.sx`); 6 tests incl. per-viewer ACL + cross-post
   dedupe. (134/134 total.)
+- [x] Per-verb dedupe rules (briefing gotcha #3) — `feed/dedupe-smart` /
+  `feed/smart-key`: reactions (like/follow/boost/...) collapse cross-actor on
+  (verb,object); posts stay distinct per actor. `feed/collapse-verbs` is
+  rebindable policy; 9 tests. (143/143 total.)
 
 (none)