feed: feed/home capstone — fanout∘inbox∘dedupe∘ACL∘rank∘take as one line + 6 tests

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

lib/feed/tests/home.sx

@@ -0,0 +1,73 @@
+; Follow-up — feed/home capstone pipeline. (feed-test name got expected)
+
+; alice follows star and bob (edges: follower followee)
+(define
+  G
+  (feed/follow-graph (list (list "alice" "star") (list "alice" "bob"))))
+
+; star posts s1 then s2; bob posts b1; star re-posts s1 (cross-post dup);
+; zoe posts z1 (alice does NOT follow zoe)
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "star" "post" "s1" 10 (list))
+      (feed/activity "star" "post" "s2" 20 (list))
+      (feed/activity "bob" "post" "b1" 15 (list))
+      (feed/activity "star" "post" "s1" 5 (list))
+      (feed/activity "zoe" "post" "z1" 30 (list)))))
+
+(define rec (feed/recency 100 10))
+
+(feed-test
+  "home count (deduped, followed only)"
+  (feed/count (feed/home S G "alice" feed/permit-public? rec 10))
+  3)
+
+(feed-test
+  "home order by recency"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/home S G "alice" feed/permit-public? rec 10)))
+  (list "s2" "b1" "s1"))
+
+(feed-test
+  "home excludes unfollowed zoe"
+  (feed/-elem?
+    "z1"
+    (map
+      (fn (a) (get a :object))
+      (feed/items (feed/home S G "alice" feed/permit-public? rec 10))))
+  false)
+
+(feed-test
+  "home top-2"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/home S G "alice" feed/permit-public? rec 2)))
+  (list "s2" "b1"))
+
+(feed-test
+  "home dedupes cross-post (one s1)"
+  (len
+    (filter
+      (fn (o) (equal? o "s1"))
+      (map
+        (fn (a) (get a :object))
+        (feed/items
+          (feed/home S G "alice" feed/permit-public? rec 10)))))
+  1)
+
+; ACL applied per-viewer in the home pipeline
+(define
+  Sacl
+  (feed/stream
+    (list (feed/normalize {:actor "star" :object "pub" :at 20}) (feed/normalize {:actor "star" :object "sec" :visible-to (list "carol") :at 25}))))
+(define Gacl (feed/follow-graph (list (list "alice" "star"))))
+
+(feed-test
+  "home hides activity alice not permitted"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/home Sacl Gacl "alice" feed/permit-acl? rec 10)))
+  (list "pub"))