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/conformance.sh

@@ -13,7 +13,7 @@ if [ ! -x "$SX_SERVER" ]; then
   exit 1
 fi
 
-SUITES=(basic fanout rank integration content notify)
+SUITES=(basic fanout rank integration content notify home)
 
 OUT_JSON="lib/feed/scoreboard.json"
 OUT_MD="lib/feed/scoreboard.md"
@@ -39,6 +39,7 @@ run_suite() {
 (load "lib/feed/fed.sx")
 (load "lib/feed/content.sx")
 (load "lib/feed/notify.sx")
+(load "lib/feed/home.sx")
 (epoch 2)
 (eval "(define feed-test-pass 0)")
 (eval "(define feed-test-fail 0)")

lib/feed/home.sx

@@ -0,0 +1,23 @@
+; feed/home — the capstone. A user's home timeline is the whole pipeline as one
+; line: fan all activities out over the follow graph, take the events landing in
+; the viewer's inbox, dedupe cross-posts, apply the viewer's ACL, rank, take N.
+;
+; Requires: fanout.sx, dedupe.sx, acl.sx (feed/timeline), rank.sx, stream.sx.
+
+; the activities in a user's inbox, as a stream
+(define
+  feed/inbox-stream
+  (fn (inbox user) (feed/stream (feed/inbox-activities inbox user))))
+
+; fanout ∘ inbox ∘ dedupe ∘ ACL ∘ rank ∘ take
+(define
+  feed/home
+  (fn
+    (stream graph viewer permit? score-fn n)
+    (feed/timeline
+      (feed/dedupe-activities
+        (feed/inbox-stream (feed/fanout stream graph) viewer))
+      viewer
+      permit?
+      score-fn
+      n)))

lib/feed/scoreboard.json

@@ -5,9 +5,10 @@
     "rank": {"pass": 24, "fail": 0},
     "integration": {"pass": 22, "fail": 0},
     "content": {"pass": 15, "fail": 0},
-    "notify": {"pass": 8, "fail": 0}
+    "notify": {"pass": 8, "fail": 0},
+    "home": {"pass": 6, "fail": 0}
   },
-  "total_pass": 128,
+  "total_pass": 134,
   "total_fail": 0,
-  "total": 128
+  "total": 134
 }

lib/feed/scoreboard.md

@@ -10,4 +10,5 @@ _Generated by `lib/feed/conformance.sh`_
 | integration | 22 | 0 | 22 |
 | content | 15 | 0 | 15 |
 | notify | 8 | 0 | 8 |
-| **Total** | **128** | **0** | **128** |
+| home | 6 | 0 | 6 |
+| **Total** | **134** | **0** | **134** |

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"))

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` → **128/128** (Phases 1–4 + TF-IDF + notifications)
+`bash lib/feed/conformance.sh` → **134/134** (Phases 1–4 + TF-IDF + notifications + home)
 
 ## Ground rules
 
@@ -144,6 +144,9 @@ are function parameters. Real acl-sx / fed-sx wire in at the call site unchanged
 - [x] Notification feed (verb-filtered, per-recipient) — `notify.sx`:
   `feed/notifications`, `feed/notify-verbs`, `feed/notify-digest` (collapses
   "X, Y liked Z" by (verb,object), sorted-deterministic); 8 tests. (128/128 total.)
+- [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.)
 
 (none)