search: prefix/wildcard queries + 14 tests

prefixTerms matches indexed terms by prefix (allTerms + isPrefixOf); prefixDocs
unions their docs; prefixRankTfIdf ranks via the matched terms. 136/136.

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

lib/feed/acl.sx

@@ -0,0 +1,38 @@
+; feed/acl — per-viewer visibility filtering. The same candidate stream yields
+; different timelines for different viewers, so ACL is applied per request and
+; pre-ACL timelines are never cached.
+;
+; permit? is injected: (permit? viewer activity) -> bool. Wire a real acl-sx
+; predicate here; feed/permit-acl? is a self-contained default that reads an
+; optional :visible-to allowlist on the activity.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem?), lib/feed/rank.sx (feed/top).
+
+; default permit: actor always sees own activity; absent/nil :visible-to is
+; public; otherwise viewer must be in the allowlist.
+(define
+  feed/permit-acl?
+  (fn
+    (viewer a)
+    (or
+      (equal? viewer (get a :actor))
+      (let
+        ((allowed (get a :visible-to nil)))
+        (if (= allowed nil) true (feed/-elem? viewer allowed))))))
+
+(define feed/permit-public? (fn (viewer a) true))
+
+; filter a stream to what viewer may read
+(define
+  feed/visible
+  (fn
+    (stream viewer permit?)
+    (feed/filter stream (fn (a) (permit? viewer a)))))
+
+; the capstone: candidate stream -> ACL for viewer -> rank -> top-N
+(define
+  feed/timeline
+  (fn
+    (stream viewer permit? score-fn n)
+    (feed/top (feed/visible stream viewer permit?) score-fn n)))

lib/feed/aggregate.sx

@@ -0,0 +1,62 @@
+; feed/aggregate — group-by / counting via key-reduce. Keys must be strings
+; (dict keys), so composite keys (actor, day) are joined into one string.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx.
+
+; group activities into a dict: key-string -> (list of activities), order-preserving
+(define
+  feed/group-by
+  (fn
+    (stream key-fn)
+    (reduce
+      (fn
+        (g a)
+        (let
+          ((k (key-fn a)))
+          (assoc g k (append (get g k (list)) (list a)))))
+      {}
+      (feed/items stream))))
+
+; key-string -> count
+(define
+  feed/group-count
+  (fn
+    (stream key-fn)
+    (reduce
+      (fn
+        (g a)
+        (let
+          ((k (key-fn a)))
+          (assoc g k (+ (get g k 0) 1))))
+      {}
+      (feed/items stream))))
+
+; --- composite keys ---------------------------------------------------------
+
+(define feed/day (fn (at window) (floor (/ at window))))
+
+; (actor, day-bucket) -> "actor#day"
+(define
+  feed/actor-day-key
+  (fn
+    (window)
+    (fn
+      (a)
+      (string-append
+        (get a :actor)
+        "#"
+        (number->string (feed/day (get a :at) window))))))
+
+(define
+  feed/by-actor-day
+  (fn (stream window) (feed/group-count stream (feed/actor-day-key window))))
+
+; per-actor activity counts
+(define
+  feed/actor-counts
+  (fn (stream) (feed/group-count stream feed/actor)))
+
+; per-object activity counts (engagement)
+(define
+  feed/object-counts
+  (fn (stream) (feed/group-count stream feed/object)))

lib/feed/api.sx

@@ -0,0 +1,24 @@
+; feed/api — ergonomic API over the stream layer for non-APL callers.
+; A single mutable activity log; post appends, all returns it as a stream.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx (loaded by harness).
+
+(define feed/-log (list))
+
+; post — normalize then append. Returns the stored activity.
+(define
+  feed/post
+  (fn
+    (raw)
+    (let
+      ((a (feed/normalize raw)))
+      (begin (set! feed/-log (append feed/-log (list a))) a))))
+
+; all — the whole log as a stream (insertion order)
+(define feed/all (fn () (feed/stream feed/-log)))
+
+; reset! — clear the log (test hygiene)
+(define feed/reset! (fn () (begin (set! feed/-log (list)) nil)))
+
+; size — number of posted activities
+(define feed/size (fn () (len feed/-log)))

lib/feed/conformance.sh

@@ -0,0 +1,125 @@
+#!/usr/bin/env bash
+# lib/feed/conformance.sh — run feed test suites, emit scoreboard.json + scoreboard.md.
+
+set -uo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="${SX_SERVER:-/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe}"
+if [ ! -x "$SX_SERVER" ]; then
+  SX_SERVER="hosts/ocaml/_build/default/bin/sx_server.exe"
+fi
+if [ ! -x "$SX_SERVER" ]; then
+  echo "ERROR: sx_server.exe not found." >&2
+  exit 1
+fi
+
+SUITES=(basic fanout rank integration content notify home dedupe trending mute page thread)
+
+OUT_JSON="lib/feed/scoreboard.json"
+OUT_MD="lib/feed/scoreboard.md"
+
+run_suite() {
+  local suite=$1
+  local file="lib/feed/tests/${suite}.sx"
+  local TMP
+  TMP=$(mktemp)
+  cat > "$TMP" << EPOCHS
+(epoch 1)
+(load "spec/stdlib.sx")
+(load "lib/r7rs.sx")
+(load "lib/apl/runtime.sx")
+(load "lib/feed/normalize.sx")
+(load "lib/feed/stream.sx")
+(load "lib/feed/api.sx")
+(load "lib/feed/fanout.sx")
+(load "lib/feed/dedupe.sx")
+(load "lib/feed/aggregate.sx")
+(load "lib/feed/rank.sx")
+(load "lib/feed/acl.sx")
+(load "lib/feed/fed.sx")
+(load "lib/feed/content.sx")
+(load "lib/feed/notify.sx")
+(load "lib/feed/home.sx")
+(load "lib/feed/trending.sx")
+(load "lib/feed/mute.sx")
+(load "lib/feed/page.sx")
+(load "lib/feed/thread.sx")
+(epoch 2)
+(eval "(define feed-test-pass 0)")
+(eval "(define feed-test-fail 0)")
+(eval "(define feed-test (fn (name got expected) (if (= got expected) (set! feed-test-pass (+ feed-test-pass 1)) (set! feed-test-fail (+ feed-test-fail 1)))))")
+(epoch 3)
+(load "${file}")
+(epoch 4)
+(eval "(list feed-test-pass feed-test-fail)")
+EPOCHS
+
+  local OUTPUT
+  OUTPUT=$(timeout 300 "$SX_SERVER" < "$TMP" 2>/dev/null)
+  rm -f "$TMP"
+
+  local LINE
+  LINE=$(echo "$OUTPUT" | awk '/^\(ok-len 4 / {getline; print; exit}')
+  if [ -z "$LINE" ]; then
+    LINE=$(echo "$OUTPUT" | grep -E '^\(ok 4 \([0-9]+ [0-9]+\)\)' | tail -1 \
+            | sed -E 's/^\(ok 4 //; s/\)$//')
+  fi
+
+  local P F
+  P=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\1/')
+  F=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\2/')
+  P=${P:-0}
+  F=${F:-0}
+  echo "${P} ${F}"
+}
+
+declare -A SUITE_PASS
+declare -A SUITE_FAIL
+TOTAL_PASS=0
+TOTAL_FAIL=0
+
+echo "Running feed conformance suite..." >&2
+for s in "${SUITES[@]}"; do
+  read -r p f < <(run_suite "$s")
+  SUITE_PASS[$s]=$p
+  SUITE_FAIL[$s]=$f
+  TOTAL_PASS=$((TOTAL_PASS + p))
+  TOTAL_FAIL=$((TOTAL_FAIL + f))
+  printf "  %-12s %d/%d\n" "$s" "$p" "$((p+f))" >&2
+done
+
+# scoreboard.json
+{
+  printf '{\n'
+  printf '  "suites": {\n'
+  first=1
+  for s in "${SUITES[@]}"; do
+    if [ $first -eq 0 ]; then printf ',\n'; fi
+    printf '    "%s": {"pass": %d, "fail": %d}' "$s" "${SUITE_PASS[$s]}" "${SUITE_FAIL[$s]}"
+    first=0
+  done
+  printf '\n  },\n'
+  printf '  "total_pass": %d,\n' "$TOTAL_PASS"
+  printf '  "total_fail": %d,\n' "$TOTAL_FAIL"
+  printf '  "total": %d\n' "$((TOTAL_PASS + TOTAL_FAIL))"
+  printf '}\n'
+} > "$OUT_JSON"
+
+# scoreboard.md
+{
+  printf '# feed Conformance Scoreboard\n\n'
+  printf '_Generated by `lib/feed/conformance.sh`_\n\n'
+  printf '| Suite | Pass | Fail | Total |\n'
+  printf '|-------|-----:|-----:|------:|\n'
+  for s in "${SUITES[@]}"; do
+    p=${SUITE_PASS[$s]}
+    f=${SUITE_FAIL[$s]}
+    printf '| %s | %d | %d | %d |\n' "$s" "$p" "$f" "$((p+f))"
+  done
+  printf '| **Total** | **%d** | **%d** | **%d** |\n' "$TOTAL_PASS" "$TOTAL_FAIL" "$((TOTAL_PASS + TOTAL_FAIL))"
+} > "$OUT_MD"
+
+echo "Wrote $OUT_JSON and $OUT_MD" >&2
+echo "Total: $TOTAL_PASS pass, $TOTAL_FAIL fail" >&2
+
+[ "$TOTAL_FAIL" -eq 0 ]

lib/feed/content.sx

@@ -0,0 +1,68 @@
+; feed/content — TF-IDF relevance over activity :tags. Rare tags carry more
+; signal, so an activity matching an uncommon tag ranks above one matching a
+; common tag. Composes with rank.sx: feed/tfidf-score is just another scorer.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-distinct), lib/feed/rank.sx (feed/rank).
+
+; document frequency: tag -> number of activities whose :tags contain it
+; (a tag repeated within one activity counts once toward df)
+(define
+  feed/tag-df
+  (fn
+    (stream)
+    (reduce
+      (fn
+        (df a)
+        (reduce
+          (fn (d t) (assoc d t (+ (get d t 0) 1)))
+          df
+          (feed/-distinct (get a :tags))))
+      {}
+      (feed/items stream))))
+
+; inverse document frequency: tag -> log(N / df)
+(define
+  feed/tag-idf
+  (fn
+    (stream)
+    (let
+      ((n (feed/count stream)) (df (feed/tag-df stream)))
+      (reduce
+        (fn (idf t) (assoc idf t (log (/ n (get df t)))))
+        {}
+        (keys df)))))
+
+; term frequency within one activity: tag -> occurrence count
+(define
+  feed/-tf
+  (fn
+    (a)
+    (reduce
+      (fn (tf t) (assoc tf t (+ (get tf t 0) 1)))
+      {}
+      (get a :tags))))
+
+; relevance of an activity to a query (list of tags) given precomputed idf:
+; sum over query tags of tf(tag in activity) * idf(tag in corpus)
+(define
+  feed/tfidf-score
+  (fn
+    (idf query)
+    (fn
+      (a)
+      (let
+        ((tf (feed/-tf a)))
+        (reduce
+          (fn
+            (acc t)
+            (+ acc (* (get tf t 0) (get idf t 0))))
+          0
+          query)))))
+
+; rank a stream by relevance to query tags (idf computed over the stream itself)
+(define
+  feed/by-relevance
+  (fn
+    (stream query)
+    (feed/rank stream (feed/tfidf-score (feed/tag-idf stream) query))))

lib/feed/dedupe.sx

@@ -0,0 +1,76 @@
+; feed/dedupe — collapse duplicate items, keeping first occurrence per key.
+; Each verb may want its own key (see briefing): "alice posted X" keys on
+; (actor verb object) — distinct per actor; "alice liked X / bob liked X"
+; collapse on (verb object) so the cross-actor likes fold into one.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem? lives in fanout.sx).
+
+; generic: dedupe a stream by key-fn, first occurrence wins (stable)
+(define
+  feed/-dedup-by
+  (fn
+    (items key-fn)
+    (get
+      (reduce
+        (fn
+          (st x)
+          (let
+            ((k (key-fn x)))
+            (if (feed/-elem? k (get st :seen)) st {:seen (append (get st :seen) (list k)) :out (append (get st :out) (list x))})))
+        {:seen (list) :out (list)}
+        items)
+      :out)))
+
+(define
+  feed/dedupe
+  (fn
+    (stream key-fn)
+    (feed/stream (feed/-dedup-by (feed/items stream) key-fn))))
+
+; --- keys -------------------------------------------------------------------
+
+(define
+  feed/activity-key
+  (fn (a) (list (get a :actor) (get a :verb) (get a :object))))
+
+; collapse cross-actor duplicates of the same verb+object (e.g. likes)
+(define feed/collapse-key (fn (a) (list (get a :verb) (get a :object))))
+
+; per-receiver inbox key — one inbox event per (receiver, actor, verb, object)
+(define
+  feed/event-key
+  (fn
+    (ev)
+    (let
+      ((a (get ev :activity)))
+      (list (get ev :to) (get a :actor) (get a :verb) (get a :object)))))
+
+; verbs whose duplicates collapse across actors (reactions, not authorship).
+; rebindable: callers can (set! feed/collapse-verbs ...) to tune the policy.
+(define
+  feed/collapse-verbs
+  (list "like" "favourite" "follow" "boost" "repost"))
+
+; per-verb key: collapse-verbs fold on (verb object); the rest key on
+; (actor verb object).
+(define
+  feed/smart-key
+  (fn
+    (a)
+    (if
+      (feed/-elem? (get a :verb) feed/collapse-verbs)
+      (feed/collapse-key a)
+      (feed/activity-key a))))
+
+; --- ready-made dedupers ----------------------------------------------------
+
+(define feed/dedupe-activities (fn (s) (feed/dedupe s feed/activity-key)))
+
+(define feed/dedupe-collapse (fn (s) (feed/dedupe s feed/collapse-key)))
+
+; verb-aware: reactions collapse cross-actor, posts stay distinct per actor
+(define feed/dedupe-smart (fn (s) (feed/dedupe s feed/smart-key)))
+
+; dedupe an inbox: at most one event per receiver per (actor verb object)
+(define feed/dedupe-inbox (fn (inbox) (feed/dedupe inbox feed/event-key)))

lib/feed/fanout.sx

@@ -0,0 +1,114 @@
+; feed/fanout — THE SHOWCASE. Fan activities out to followers via the APL outer
+; product (∘.×). activities ∘.× audience → an (activity × follower) matrix of
+; inbox events; flatten to a vector; guard-keep only real follow edges.
+;
+; Requires: lib/apl/runtime.sx, lib/feed/normalize.sx, lib/feed/stream.sx.
+;
+; NOTE: apl-outer's combiner result is run through (if (scalar? r) (disclose r) r).
+; A bare dict counts as a scalar (shape ()) and disclose nils it — so the combiner
+; must (enclose ...) its event dict; apl-outer then discloses it back intact.
+
+; --- graph: {followee -> (list of followers)} -------------------------------
+
+(define feed/followers (fn (graph user) (get graph user (list))))
+
+; build a graph from (follower followee) edges: "follower follows followee"
+(define
+  feed/follow-graph
+  (fn
+    (edges)
+    (reduce
+      (fn
+        (g e)
+        (let
+          ((follower (first e)) (followee (nth e 1)))
+          (assoc
+            g
+            followee
+            (append (feed/followers g followee) (list follower)))))
+      {}
+      edges)))
+
+; --- helpers ----------------------------------------------------------------
+
+; unwrap an apl-scalar (has :ravel) back to its value; pass activities through
+(define
+  feed/-val
+  (fn
+    (x)
+    (if (and (= (type-of x) "dict") (has-key? x :ravel)) (disclose x) x)))
+
+(define feed/-elem? (fn (x lst) (some (fn (y) (equal? x y)) lst)))
+
+(define
+  feed/-distinct
+  (fn
+    (lst)
+    (if
+      (= (len lst) 0)
+      (list)
+      (get (apl-unique (make-array (list (len lst)) lst)) :ravel))))
+
+; rank-2 matrix -> rank-1 stream of its ravel
+(define feed/-flatten (fn (arr) (feed/stream (get arr :ravel))))
+
+; distinct receivers across the whole graph, sorted for determinism
+; (dict key order is unspecified, so sort to pin audience/recipient ordering)
+(define
+  feed/audience
+  (fn
+    (graph)
+    (sort
+      (feed/-distinct
+        (reduce
+          (fn (acc k) (append acc (feed/followers graph k)))
+          (list)
+          (keys graph))))))
+
+; --- the outer product ------------------------------------------------------
+
+; one (activity, follower) inbox event, enclosed so apl-outer keeps the dict
+(define feed/-mk-event (fn (a f) (enclose {:activity (feed/-val a) :to (feed/-val f)})))
+
+; keep events where :to actually follows the activity's actor
+(define
+  feed/-edge?
+  (fn
+    (graph)
+    (fn
+      (ev)
+      (feed/-elem?
+        (get ev :to)
+        (feed/followers graph (get (get ev :activity) :actor))))))
+
+; fanout — activities ∘.× audience, flatten, guard-keep real edges
+(define
+  feed/fanout
+  (fn
+    (stream graph)
+    (let
+      ((matrix (apl-outer feed/-mk-event stream (feed/stream (feed/audience graph)))))
+      (feed/filter (feed/-flatten matrix) (feed/-edge? graph)))))
+
+; --- inbox queries ----------------------------------------------------------
+
+(define
+  feed/inbox-for
+  (fn
+    (inbox user)
+    (feed/filter inbox (fn (ev) (equal? (get ev :to) user)))))
+
+(define
+  feed/recipients
+  (fn
+    (inbox)
+    (feed/-distinct (map (fn (ev) (get ev :to)) (feed/items inbox)))))
+
+; the activities (unwrapped) destined for a user
+(define
+  feed/inbox-activities
+  (fn
+    (inbox user)
+    (map
+      (fn (ev) (get ev :activity))
+      (feed/items (feed/inbox-for inbox user)))))

lib/feed/fed.sx

@@ -0,0 +1,60 @@
+; feed/fed — federation. Outbound: a local post fans out, then splits into local
+; vs remote inboxes; remote events are handed to an injected send-fn. Inbound:
+; peer activities merge into the local stream, deduped. Backfill: pull peer
+; history via an injected fetch-fn and merge.
+;
+; remote? / send-fn / fetch-fn are injected so real fed-sx transport wires in here
+; without feed depending on it.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx,
+; lib/feed/dedupe.sx.
+
+; --- merge / ingest ---------------------------------------------------------
+
+(define
+  feed/merge
+  (fn (s1 s2) (feed/stream (append (feed/items s1) (feed/items s2)))))
+
+; merge a peer stream into local, dropping (actor verb object) duplicates
+(define
+  feed/ingest
+  (fn (local peer) (feed/dedupe-activities (feed/merge local peer))))
+
+; --- inbound ----------------------------------------------------------------
+
+; peer pushes raw activities to the local inbox; normalize + ingest
+(define
+  feed/inbound
+  (fn
+    (local raw-activities)
+    (feed/ingest local (feed/stream (map feed/normalize raw-activities)))))
+
+; backfill on subscribe: pull peer history via fetch-fn, normalize, ingest
+(define
+  feed/backfill
+  (fn (local fetch-fn peer-id) (feed/inbound local (fetch-fn peer-id))))
+
+; --- outbound ---------------------------------------------------------------
+
+; split an inbox into local vs remote deliveries by viewer-id predicate
+(define feed/partition-inbox (fn (inbox remote?) {:local (feed/filter inbox (fn (ev) (not (remote? (get ev :to))))) :remote (feed/filter inbox (fn (ev) (remote? (get ev :to))))}))
+
+; fan a stream out over the graph, then partition by locality
+(define
+  feed/federate
+  (fn
+    (stream graph remote?)
+    (feed/partition-inbox (feed/fanout stream graph) remote?)))
+
+; deliver: hand each remote event to send-fn, return the local inbox to enqueue
+(define
+  feed/deliver
+  (fn
+    (stream graph remote? send-fn)
+    (let
+      ((parts (feed/federate stream graph remote?)))
+      (begin
+        (for-each
+          (fn (ev) (send-fn (get ev :to) (get ev :activity)))
+          (feed/items (get parts :remote)))
+        (get parts :local)))))

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/mute.sx

@@ -0,0 +1,44 @@
+; feed/mute — viewer-controlled filtering. ACL (acl.sx) is author-controlled
+; visibility; mute is the reader's own preference: hide muted actors or tags.
+; Like ACL it is per-viewer and applied per request, never cached.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem?).
+
+; drop activities authored by a muted actor
+(define
+  feed/mute-actors
+  (fn
+    (stream actors)
+    (feed/filter
+      stream
+      (fn (a) (not (feed/-elem? (get a :actor) actors))))))
+
+; drop activities carrying any muted tag
+(define
+  feed/mute-tags
+  (fn
+    (stream tags)
+    (feed/filter
+      stream
+      (fn (a) (not (some (fn (t) (feed/-elem? t tags)) (get a :tags)))))))
+
+; drop activities about a muted object (thread mute)
+(define
+  feed/mute-objects
+  (fn
+    (stream objects)
+    (feed/filter
+      stream
+      (fn (a) (not (feed/-elem? (get a :object) objects))))))
+
+; apply a viewer preference bag: {:mute-actors (...) :mute-tags (...) :mute-objects (...)}
+(define
+  feed/apply-prefs
+  (fn
+    (stream prefs)
+    (feed/mute-objects
+      (feed/mute-tags
+        (feed/mute-actors stream (get prefs :mute-actors (list)))
+        (get prefs :mute-tags (list)))
+      (get prefs :mute-objects (list)))))

lib/feed/normalize.sx

@@ -0,0 +1,31 @@
+; feed/normalize — coerce arbitrary input into the canonical activity record.
+; An activity is a small dict {:actor :verb :object :at :tags}; a stream is an
+; APL vector of such dicts (see stream.sx). Extra keys on the raw input survive
+; (e.g. :visible-to for ACL, peer metadata for federation) — :tags is the
+; flexible bag but the record is not closed.
+
+(define feed/activity-keys (list :actor :verb :object :at :tags))
+
+(define
+  feed/normalize
+  (fn
+    (raw)
+    (let
+      ((d (if (= (type-of raw) "dict") raw {})))
+      (merge d {:actor (get d :actor "") :object (get d :object nil) :at (get d :at 0) :tags (let ((t (get d :tags (list)))) (if (list? t) t (list t))) :verb (get d :verb "post")}))))
+
+(define
+  feed/activity
+  (fn (actor verb object at tags) (feed/normalize {:actor actor :object object :at at :tags tags :verb verb})))
+
+(define feed/actor (fn (a) (get a :actor)))
+(define feed/verb (fn (a) (get a :verb)))
+(define feed/object (fn (a) (get a :object)))
+(define feed/at (fn (a) (get a :at)))
+(define feed/tags (fn (a) (get a :tags)))
+
+(define
+  feed/activity?
+  (fn
+    (a)
+    (and (= (type-of a) "dict") (has-key? a :actor) (has-key? a :verb))))

lib/feed/notify.sx

@@ -0,0 +1,45 @@
+; feed/notify — a notification feed is a thin layer over a recipient's inbox:
+; the events directed at a user, optionally verb-filtered, and a digest that
+; collapses "alice, bob and 1 other liked X" by (verb, object).
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/inbox-for, feed/-elem?).
+
+; all inbox events for a user (their raw notifications)
+(define feed/notifications (fn (inbox user) (feed/inbox-for inbox user)))
+
+; restrict to notification-worthy verbs (e.g. (list "like" "reply" "follow"))
+(define
+  feed/notify-verbs
+  (fn
+    (inbox user verbs)
+    (feed/filter
+      (feed/inbox-for inbox user)
+      (fn (ev) (feed/-elem? (get (get ev :activity) :verb) verbs)))))
+
+; group key "verb|object" — deterministic, sortable
+(define
+  feed/-notify-key
+  (fn
+    (ev)
+    (let
+      ((a (get ev :activity)))
+      (string-append (get a :verb) "|" (get a :object)))))
+
+; digest: one entry per (verb, object) with the distinct actors and a count,
+; ordered by key for determinism.
+(define
+  feed/notify-digest
+  (fn
+    (inbox user)
+    (let
+      ((events (feed/items (feed/inbox-for inbox user))))
+      (let
+        ((groups (reduce (fn (g ev) (let ((a (get ev :activity)) (k (feed/-notify-key ev))) (let ((cur (get g k {:object (get a :object) :actors (list) :verb (get a :verb)}))) (assoc g k (assoc cur :actors (append (get cur :actors) (list (get a :actor)))))))) {} events)))
+        (map
+          (fn
+            (k)
+            (let
+              ((grp (get groups k)))
+              (assoc grp :count (len (get grp :actors)))))
+          (sort (keys groups)))))))

lib/feed/page.sx

@@ -0,0 +1,50 @@
+; feed/page — pagination. Offset/limit for indexed access, and cursor-based
+; (by :at) for recency feeds, which is stable under inserts: a cursor is the
+; :at of the last item seen, and the next page is the newest items older than it.
+;
+; Requires: lib/feed/stream.sx (feed/recent, feed/take, feed/filter).
+
+; --- offset / limit ---------------------------------------------------------
+
+(define
+  feed/page
+  (fn
+    (stream offset limit)
+    (feed/stream (take (drop (feed/items stream) offset) limit))))
+
+(define
+  feed/page-count
+  (fn (stream limit) (ceil (/ (feed/count stream) limit))))
+
+; --- cursor (recency feeds) -------------------------------------------------
+
+; activities strictly older than cursor (scroll down / load older)
+(define
+  feed/before
+  (fn
+    (stream cursor)
+    (feed/filter stream (fn (a) (< (get a :at) cursor)))))
+
+; activities strictly newer than cursor (load newer / "N new posts")
+(define
+  feed/after
+  (fn
+    (stream cursor)
+    (feed/filter stream (fn (a) (> (get a :at) cursor)))))
+
+; one page: the `limit` newest activities older than cursor, newest first
+(define
+  feed/page-before
+  (fn
+    (stream cursor limit)
+    (feed/take (feed/recent (feed/before stream cursor)) limit)))
+
+; cursor to fetch the next (older) page: :at of the last item of a page,
+; or nil when the page is empty (end of feed)
+(define
+  feed/next-cursor
+  (fn
+    (page)
+    (let
+      ((items (feed/items page)))
+      (if (= (len items) 0) nil (get (last items) :at)))))

lib/feed/rank.sx

@@ -0,0 +1,92 @@
+; feed/rank — scoring + ranking. Scorers are (activity -> number). Ranking is a
+; stable two-pass grade-down: first by :at descending (the tiebreak), then by
+; score descending — so ties resolve by recency, then by input order. Fully
+; deterministic on ties.
+;
+; Requires: lib/apl/runtime.sx, lib/feed/normalize.sx, lib/feed/stream.sx.
+
+; --- scorers ----------------------------------------------------------------
+
+; recency: half-life decay. score = 0.5 ^ (age / half-life). at==now -> 1.0.
+(define
+  feed/recency
+  (fn
+    (now half-life)
+    (fn (a) (expt 0.5 (/ (- now (get a :at)) half-life)))))
+
+; velocity: how many of this actor's activities fall in (at-window, at] —
+; a burst of recent activity scores higher.
+(define
+  feed/velocity
+  (fn
+    (stream window)
+    (fn
+      (a)
+      (len
+        (filter
+          (fn
+            (b)
+            (and
+              (equal? (get b :actor) (get a :actor))
+              (<= (get b :at) (get a :at))
+              (> (get b :at) (- (get a :at) window))))
+          (feed/items stream))))))
+
+; engagement: how many activities in the stream touch this activity's :object
+(define
+  feed/engagement
+  (fn
+    (stream)
+    (fn
+      (a)
+      (len
+        (filter
+          (fn (b) (equal? (get b :object) (get a :object)))
+          (feed/items stream))))))
+
+; composite: weighted sum. parts = (list (list weight scorer) ...)
+(define
+  feed/composite
+  (fn
+    (parts)
+    (fn
+      (a)
+      (reduce
+        (fn (acc p) (+ acc (* (first p) ((nth p 1) a))))
+        0
+        parts))))
+
+; --- ranking ----------------------------------------------------------------
+
+; stable reorder of items by key-fn, descending (grade-down is stable)
+(define
+  feed/-desc-by
+  (fn
+    (items key-fn)
+    (let
+      ((keys (make-array (list (len items)) (map key-fn items))))
+      (let
+        ((order (get (apl-grade-down keys) :ravel)))
+        (map (fn (i) (nth items (- i 1))) order)))))
+
+; rank by score descending; ties -> :at descending -> input order
+(define
+  feed/rank
+  (fn
+    (stream score-fn)
+    (let
+      ((by-at (feed/-desc-by (feed/items stream) feed/at)))
+      (feed/stream (feed/-desc-by by-at score-fn)))))
+
+; attach a :score to each activity (for inspection / debugging)
+(define
+  feed/with-scores
+  (fn
+    (stream score-fn)
+    (feed/stream
+      (map (fn (a) (assoc a :score (score-fn a))) (feed/items stream)))))
+
+; top-N ranked timeline
+(define
+  feed/top
+  (fn (stream score-fn n) (feed/take (feed/rank stream score-fn) n)))

lib/feed/scoreboard.json

@@ -0,0 +1,19 @@
+{
+  "suites": {
+    "basic": {"pass": 30, "fail": 0},
+    "fanout": {"pass": 29, "fail": 0},
+    "rank": {"pass": 24, "fail": 0},
+    "integration": {"pass": 22, "fail": 0},
+    "content": {"pass": 15, "fail": 0},
+    "notify": {"pass": 8, "fail": 0},
+    "home": {"pass": 6, "fail": 0},
+    "dedupe": {"pass": 9, "fail": 0},
+    "trending": {"pass": 11, "fail": 0},
+    "mute": {"pass": 9, "fail": 0},
+    "page": {"pass": 14, "fail": 0},
+    "thread": {"pass": 12, "fail": 0}
+  },
+  "total_pass": 189,
+  "total_fail": 0,
+  "total": 189
+}

lib/feed/scoreboard.md

@@ -0,0 +1,19 @@
+# feed Conformance Scoreboard
+
+_Generated by `lib/feed/conformance.sh`_
+
+| Suite | Pass | Fail | Total |
+|-------|-----:|-----:|------:|
+| basic | 30 | 0 | 30 |
+| fanout | 29 | 0 | 29 |
+| rank | 24 | 0 | 24 |
+| integration | 22 | 0 | 22 |
+| content | 15 | 0 | 15 |
+| notify | 8 | 0 | 8 |
+| home | 6 | 0 | 6 |
+| dedupe | 9 | 0 | 9 |
+| trending | 11 | 0 | 11 |
+| mute | 9 | 0 | 9 |
+| page | 14 | 0 | 14 |
+| thread | 12 | 0 | 12 |
+| **Total** | **189** | **0** | **189** |

lib/feed/stream.sx

@@ -0,0 +1,75 @@
+; feed/stream — a stream is an APL vector (rank-1 array) whose ravel holds
+; activity dicts. Operations lift APL primitives onto this shape: filter via
+; compress (/), sort via grade (⍋), take via ↑, reverse via ⌽.
+;
+; Requires: lib/apl/runtime.sx, lib/feed/normalize.sx (loaded by harness).
+
+(define feed/stream (fn (acts) (make-array (list (len acts)) acts)))
+
+(define feed/items (fn (s) (get s :ravel)))
+
+(define feed/count (fn (s) (len (get s :ravel))))
+
+(define feed/empty (feed/stream (list)))
+
+(define feed/empty? (fn (s) (= (feed/count s) 0)))
+
+; filter — bool mask ∘ compress. pred : activity -> truthy
+(define
+  feed/filter
+  (fn
+    (s pred)
+    (let
+      ((items (get s :ravel)))
+      (let
+        ((mask (make-array (list (len items)) (map (fn (a) (if (pred a) 1 0)) items))))
+        (apl-compress mask s)))))
+
+; sort-by — ascending, stable on ties (grade-up is stable). key-fn : activity -> number
+(define
+  feed/sort-by
+  (fn
+    (s key-fn)
+    (let
+      ((items (get s :ravel)))
+      (let
+        ((keys (make-array (list (len items)) (map key-fn items))))
+        (let
+          ((order (get (apl-grade-up keys) :ravel)))
+          (feed/stream (map (fn (i) (nth items (- i 1))) order)))))))
+
+(define feed/sort-by-at (fn (s) (feed/sort-by s feed/at)))
+
+; newest-first: ascending sort then reverse (⌽)
+(define feed/recent (fn (s) (apl-reverse (feed/sort-by-at s))))
+
+; take N (↑), clamped to stream length so it never over-takes/pads
+(define
+  feed/take
+  (fn
+    (s n)
+    (let
+      ((c (feed/count s)))
+      (if (>= n c) s (apl-take (apl-scalar n) s)))))
+
+(define feed/reverse (fn (s) (apl-reverse s)))
+
+; common predicates
+(define
+  feed/by-actor
+  (fn (s actor) (feed/filter s (fn (a) (equal? (get a :actor) actor)))))
+
+(define
+  feed/by-verb
+  (fn (s verb) (feed/filter s (fn (a) (equal? (get a :verb) verb)))))
+
+(define
+  feed/by-object
+  (fn
+    (s object)
+    (feed/filter s (fn (a) (equal? (get a :object) object)))))
+
+; activities at or after timestamp t
+(define
+  feed/since
+  (fn (s t) (feed/filter s (fn (a) (>= (get a :at) t)))))

lib/feed/tests/basic.sx

@@ -0,0 +1,118 @@
+; Phase 1 — normalize, stream ops, api. Uses the feed-test harness
+; (feed-test name got expected) provided by conformance.sh.
+
+; ---------- normalize ----------
+
+(feed-test
+  "normalize default actor"
+  (feed/actor (feed/normalize {}))
+  "")
+(feed-test
+  "normalize default verb"
+  (feed/verb (feed/normalize {}))
+  "post")
+(feed-test
+  "normalize default at"
+  (feed/at (feed/normalize {}))
+  0)
+(feed-test
+  "normalize default object"
+  (feed/object (feed/normalize {}))
+  nil)
+(feed-test
+  "normalize default tags"
+  (feed/tags (feed/normalize {}))
+  (list))
+(feed-test
+  "normalize keeps actor"
+  (feed/actor (feed/normalize {:actor "alice"}))
+  "alice")
+(feed-test
+  "normalize keeps verb"
+  (feed/verb (feed/normalize {:verb "like"}))
+  "like")
+(feed-test
+  "normalize scalar tag -> list"
+  (feed/tags (feed/normalize {:tags "x"}))
+  (list "x"))
+(feed-test
+  "normalize list tags kept"
+  (feed/tags (feed/normalize {:tags (list "a" "b")}))
+  (list "a" "b"))
+(feed-test
+  "activity constructor at"
+  (feed/at (feed/activity "a" "post" "o" 5 (list)))
+  5)
+(feed-test
+  "activity? on activity"
+  (feed/activity? (feed/normalize {:actor "a"}))
+  true)
+(feed-test "activity? on number" (feed/activity? 5) false)
+(feed-test "activity? on bare dict" (feed/activity? {:foo 1}) false)
+
+; ---------- stream ----------
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 30 (list))
+      (feed/activity "bob" "like" "p1" 10 (list))
+      (feed/activity "alice" "post" "p2" 20 (list)))))
+
+(feed-test "stream count" (feed/count S) 3)
+(feed-test "stream items len" (len (feed/items S)) 3)
+(feed-test
+  "sort-by-at actors asc"
+  (map feed/actor (feed/items (feed/sort-by-at S)))
+  (list "bob" "alice" "alice"))
+(feed-test
+  "recent newest first"
+  (map feed/at (feed/items (feed/recent S)))
+  (list 30 20 10))
+(feed-test
+  "take 2 of recent"
+  (feed/count (feed/take (feed/recent S) 2))
+  2)
+(feed-test
+  "take clamps past end"
+  (feed/count (feed/take S 10))
+  3)
+(feed-test
+  "by-actor alice count"
+  (feed/count (feed/by-actor S "alice"))
+  2)
+(feed-test
+  "by-verb like actor"
+  (map feed/actor (feed/items (feed/by-verb S "like")))
+  (list "bob"))
+(feed-test
+  "by-object p1 count"
+  (feed/count (feed/by-object S "p1"))
+  2)
+(feed-test
+  "since 20 count"
+  (feed/count (feed/since S 20))
+  2)
+(feed-test
+  "reverse ats"
+  (map feed/at (feed/items (feed/reverse S)))
+  (list 20 10 30))
+(feed-test "empty? on empty" (feed/empty? feed/empty) true)
+(feed-test
+  "empty? on filtered-out"
+  (feed/empty? (feed/by-actor S "zzz"))
+  true)
+
+; ---------- api ----------
+
+(feed/reset!)
+(feed/post {:actor "x" :at 1 :verb "post"})
+(feed/post {:actor "y" :at 2 :verb "like"})
+(feed-test "api size after posts" (feed/size) 2)
+(feed-test "api all count" (feed/count (feed/all)) 2)
+(feed-test
+  "post returns normalized verb"
+  (feed/verb (feed/post {:actor "z"}))
+  "post")
+(feed-test "api size after third post" (feed/size) 3)

lib/feed/tests/content.sx

@@ -0,0 +1,85 @@
+; Follow-up — TF-IDF content ranking over :tags. (feed-test name got expected)
+
+(define
+  corpus
+  (feed/stream
+    (list
+      (feed/normalize {:actor "u" :object "o1" :at 10 :tags (list "cats" "funny")})
+      (feed/normalize {:actor "u" :object "o2" :at 20 :tags (list "cats" "news")})
+      (feed/normalize {:actor "u" :object "o3" :at 30 :tags (list "politics" "news")})
+      (feed/normalize {:actor "u" :object "o4" :at 40 :tags (list "cats")}))))
+
+; ---------- document frequency ----------
+
+(feed-test "df cats" (get (feed/tag-df corpus) "cats") 3)
+(feed-test "df news" (get (feed/tag-df corpus) "news") 2)
+(feed-test "df funny" (get (feed/tag-df corpus) "funny") 1)
+(feed-test "df politics" (get (feed/tag-df corpus) "politics") 1)
+(feed-test "df full" (feed/tag-df corpus) {:news 2 :funny 1 :politics 1 :cats 3})
+
+; ---------- inverse document frequency ----------
+
+(feed-test
+  "idf news = log(4/2)"
+  (get (feed/tag-idf corpus) "news")
+  (log 2))
+(feed-test
+  "idf funny = log(4/1)"
+  (get (feed/tag-idf corpus) "funny")
+  (log 4))
+(feed-test
+  "rarer tag has higher idf"
+  (>
+    (get (feed/tag-idf corpus) "funny")
+    (get (feed/tag-idf corpus) "cats"))
+  true)
+
+; ---------- tf-idf scoring ----------
+
+(define idf (feed/tag-idf corpus))
+
+(feed-test
+  "score query funny on o1"
+  ((feed/tfidf-score idf (list "funny")) (feed/normalize {:actor "u" :object "x" :tags (list "cats" "funny")}))
+  (log 4))
+(feed-test
+  "score query funny on non-match"
+  ((feed/tfidf-score idf (list "funny")) (feed/normalize {:actor "u" :object "x" :tags (list "cats")}))
+  0)
+(feed-test
+  "unknown query tag scores 0"
+  ((feed/tfidf-score idf (list "zzz")) (feed/normalize {:actor "u" :object "x" :tags (list "cats")}))
+  0)
+
+; ---------- ranking by relevance ----------
+
+; query news: o2,o3 match (score log2), o1,o4 don't (0); ties break by :at desc
+(feed-test
+  "by-relevance news order"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/by-relevance corpus (list "news"))))
+  (list "o3" "o2" "o4" "o1"))
+
+; query funny: only o1 matches -> ranks first
+(feed-test
+  "by-relevance funny first"
+  (get
+    (nth (feed/items (feed/by-relevance corpus (list "funny"))) 0)
+    :object)
+  "o1")
+
+; query (cats news): o2 carries both tags -> highest combined tf-idf
+(feed-test
+  "by-relevance cats+news top"
+  (get
+    (nth
+      (feed/items (feed/by-relevance corpus (list "cats" "news")))
+      0)
+    :object)
+  "o2")
+
+(feed-test
+  "by-relevance preserves count"
+  (feed/count (feed/by-relevance corpus (list "cats")))
+  4)

lib/feed/tests/dedupe.sx

@@ -0,0 +1,56 @@
+; Follow-up — verb-aware (smart) dedupe. (feed-test name got expected)
+
+; reactions (like/follow) collapse cross-actor; posts stay distinct per actor
+(define
+  M
+  (feed/stream
+    (list
+      (feed/activity "alice" "like" "X" 1 (list))
+      (feed/activity "bob" "like" "X" 2 (list))
+      (feed/activity "alice" "post" "P" 3 (list))
+      (feed/activity "bob" "post" "P" 4 (list))
+      (feed/activity "alice" "follow" "C" 5 (list))
+      (feed/activity "bob" "follow" "C" 6 (list))))) ; collapses
+
+(feed-test
+  "smart dedupe total"
+  (feed/count (feed/dedupe-smart M))
+  4)
+(feed-test
+  "smart keeps both posts"
+  (feed/count (feed/by-verb (feed/dedupe-smart M) "post"))
+  2)
+(feed-test
+  "smart collapses likes to one"
+  (feed/count (feed/by-verb (feed/dedupe-smart M) "like"))
+  1)
+(feed-test
+  "smart collapses follows to one"
+  (feed/count (feed/by-verb (feed/dedupe-smart M) "follow"))
+  1)
+(feed-test
+  "collapsed like keeps first actor"
+  (map feed/actor (feed/items (feed/by-verb (feed/dedupe-smart M) "like")))
+  (list "alice"))
+
+; contrast: plain activity dedupe keeps cross-actor likes distinct
+(feed-test
+  "activity dedupe keeps both likes"
+  (feed/count (feed/by-verb (feed/dedupe-activities M) "like"))
+  2)
+
+; contrast: blanket collapse folds the two posts (same verb+object) too
+(feed-test
+  "collapse dedupe folds posts"
+  (feed/count (feed/by-verb (feed/dedupe-collapse M) "post"))
+  1)
+
+; smart-key dispatch
+(feed-test
+  "smart-key reaction -> (verb object)"
+  (feed/smart-key (feed/activity "alice" "like" "X" 0 (list)))
+  (list "like" "X"))
+(feed-test
+  "smart-key post -> (actor verb object)"
+  (feed/smart-key (feed/activity "alice" "post" "P" 0 (list)))
+  (list "alice" "post" "P"))

lib/feed/tests/fanout.sx

@@ -0,0 +1,187 @@
+; Phase 2 — fanout via outer product + dedupe. (feed-test name got expected)
+
+; ---------- graph ----------
+
+; edges: (follower followee). bob,carol follow alice; carol,dave follow bob.
+(define
+  G
+  (feed/follow-graph
+    (list
+      (list "bob" "alice")
+      (list "carol" "alice")
+      (list "carol" "bob")
+      (list "dave" "bob"))))
+
+(feed-test "followers alice" (feed/followers G "alice") (list "bob" "carol"))
+(feed-test "followers bob" (feed/followers G "bob") (list "carol" "dave"))
+(feed-test "followers unknown" (feed/followers G "zzz") (list))
+(feed-test "audience distinct" (feed/audience G) (list "bob" "carol" "dave"))
+
+; ---------- fanout ----------
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 10 (list))
+      (feed/activity "alice" "post" "p2" 20 (list))
+      (feed/activity "bob" "like" "p1" 30 (list)))))
+
+(define IB (feed/fanout S G))
+
+(feed-test "fanout total edges" (feed/count IB) 6)
+(feed-test
+  "inbox bob count"
+  (feed/count (feed/inbox-for IB "bob"))
+  2)
+(feed-test
+  "inbox carol count"
+  (feed/count (feed/inbox-for IB "carol"))
+  3)
+(feed-test
+  "inbox dave count"
+  (feed/count (feed/inbox-for IB "dave"))
+  1)
+(feed-test
+  "inbox alice (follows none)"
+  (feed/count (feed/inbox-for IB "alice"))
+  0)
+(feed-test
+  "recipients order"
+  (feed/recipients IB)
+  (list "bob" "carol" "dave"))
+(feed-test
+  "bob inbox objects"
+  (map (fn (a) (get a :object)) (feed/inbox-activities IB "bob"))
+  (list "p1" "p2"))
+(feed-test
+  "dave inbox objects"
+  (map (fn (a) (get a :object)) (feed/inbox-activities IB "dave"))
+  (list "p1"))
+(feed-test
+  "dave inbox verb"
+  (map (fn (a) (get a :verb)) (feed/inbox-activities IB "dave"))
+  (list "like"))
+
+; empty graph → no audience → no edges
+(feed-test
+  "empty graph fanout"
+  (feed/count (feed/fanout S {}))
+  0)
+
+; actor nobody follows produces no edges
+(define
+  Sghost
+  (feed/stream (list (feed/activity "ghost" "post" "g1" 5 (list)))))
+(feed-test
+  "unfollowed actor fanout"
+  (feed/count (feed/fanout Sghost G))
+  0)
+
+; ---------- high fanout (popular actor) ----------
+
+(define
+  Gstar
+  (feed/follow-graph
+    (list
+      (list "u1" "star")
+      (list "u2" "star")
+      (list "u3" "star")
+      (list "u4" "star")
+      (list "u5" "star"))))
+(define
+  Sstar
+  (feed/stream (list (feed/activity "star" "post" "s1" 1 (list)))))
+(feed-test
+  "star fanout count"
+  (feed/count (feed/fanout Sstar Gstar))
+  5)
+(feed-test "star audience size" (len (feed/audience Gstar)) 5)
+
+; ---------- mutual follow ----------
+
+(define Gmut (feed/follow-graph (list (list "a" "b") (list "b" "a"))))
+(define
+  Smut
+  (feed/stream
+    (list
+      (feed/activity "a" "post" "pa" 1 (list))
+      (feed/activity "b" "post" "pb" 2 (list)))))
+(define IBmut (feed/fanout Smut Gmut))
+(feed-test "mutual total" (feed/count IBmut) 2)
+(feed-test
+  "mutual a gets pb"
+  (map (fn (x) (get x :object)) (feed/inbox-activities IBmut "a"))
+  (list "pb"))
+(feed-test
+  "mutual b gets pa"
+  (map (fn (x) (get x :object)) (feed/inbox-activities IBmut "b"))
+  (list "pa"))
+
+; ---------- dedupe ----------
+
+(define
+  Sdup2
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 1 (list))
+      (feed/activity "alice" "post" "p1" 9 (list))
+      (feed/activity "alice" "post" "p2" 2 (list)))))
+(feed-test
+  "dedupe-activities collapses dup"
+  (feed/count (feed/dedupe-activities Sdup2))
+  2)
+(feed-test
+  "dedupe-activities keeps distinct"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/dedupe-activities Sdup2)))
+  (list "p1" "p2"))
+
+(define
+  Slikes
+  (feed/stream
+    (list
+      (feed/activity "alice" "like" "X" 1 (list))
+      (feed/activity "bob" "like" "X" 2 (list))
+      (feed/activity "carol" "like" "Y" 3 (list)))))
+(feed-test
+  "collapse cross-actor likes"
+  (feed/count (feed/dedupe-collapse Slikes))
+  2)
+(feed-test
+  "collapse keeps distinct objects"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/dedupe-collapse Slikes)))
+  (list "X" "Y"))
+
+(feed-test
+  "activity-key shape"
+  (feed/activity-key (feed/activity "a" "post" "o" 0 (list)))
+  (list "a" "post" "o"))
+(feed-test
+  "collapse-key shape"
+  (feed/collapse-key (feed/activity "a" "like" "o" 0 (list)))
+  (list "like" "o"))
+
+; cross-post: alice posts p1 twice → bob's inbox has it twice → dedupe-inbox → once
+(define
+  Scross
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 1 (list))
+      (feed/activity "alice" "post" "p1" 5 (list)))))
+(define IBcross (feed/fanout Scross G))
+(feed-test
+  "cross-post raw bob count"
+  (feed/count (feed/inbox-for IBcross "bob"))
+  2)
+(feed-test
+  "cross-post deduped bob count"
+  (feed/count (feed/inbox-for (feed/dedupe-inbox IBcross) "bob"))
+  1)
+(feed-test
+  "dedupe-inbox keeps distinct receivers"
+  (feed/count (feed/dedupe-inbox IBcross))
+  2)

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"))

lib/feed/tests/integration.sx

@@ -0,0 +1,155 @@
+; Phase 4 — visibility (ACL) + federation, and the end-to-end timeline.
+; (feed-test name got expected)
+
+; ---------- ACL visibility ----------
+; pub: public. sec: bob, allows carol. dm: frank, allows dave.
+
+(define
+  C
+  (feed/stream
+    (list
+      (feed/normalize {:actor "alice" :object "pub" :at 10})
+      (feed/normalize {:actor "bob" :object "sec" :visible-to (list "carol") :at 20})
+      (feed/normalize {:actor "frank" :object "dm" :visible-to (list "dave") :at 30}))))
+
+(feed-test
+  "public visible to anyone"
+  (feed/count (feed/visible C "zoe" feed/permit-acl?))
+  1)
+(feed-test
+  "carol sees allowlisted + public"
+  (feed/count (feed/visible C "carol" feed/permit-acl?))
+  2)
+(feed-test
+  "dave sees dm + public"
+  (feed/count (feed/visible C "dave" feed/permit-acl?))
+  2)
+(feed-test
+  "author always sees own private"
+  (feed/count (feed/visible C "frank" feed/permit-acl?))
+  2)
+(feed-test
+  "permit-public? lets all through"
+  (feed/count (feed/visible C "zoe" feed/permit-public?))
+  3)
+(feed-test
+  "visible objects for dave"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/visible C "dave" feed/permit-acl?)))
+  (list "pub" "dm"))
+
+; per-viewer: same stream, different timelines
+(feed-test
+  "zoe timeline differs from carol"
+  (not
+    (=
+      (feed/count (feed/visible C "zoe" feed/permit-acl?))
+      (feed/count (feed/visible C "carol" feed/permit-acl?))))
+  true)
+
+; ---------- federation: merge / ingest ----------
+
+(define
+  L
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 10 (list))
+      (feed/activity "alice" "post" "p2" 20 (list)))))
+(define
+  P
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p2" 20 (list))
+      (feed/activity "peer" "post" "p9" 25 (list)))))
+
+(feed-test "merge concatenates" (feed/count (feed/merge L P)) 4)
+(feed-test
+  "ingest dedupes overlap"
+  (feed/count (feed/ingest L P))
+  3)
+
+(feed-test
+  "inbound normalizes + ingests"
+  (feed/count (feed/inbound L (list {:actor "peer" :object "p9" :at 25} {:actor "alice" :object "p1" :at 10})))
+  3)
+
+; backfill via injected fetch-fn
+(define peer-history (fn (peer-id) (list {:actor peer-id :object "h1" :at 1} {:actor peer-id :object "h2" :at 2})))
+(feed-test
+  "backfill merges peer history"
+  (feed/count (feed/backfill L peer-history "remote"))
+  4)
+(feed-test
+  "backfill objects present"
+  (map
+    (fn (a) (get a :object))
+    (feed/items
+      (feed/by-actor (feed/backfill L peer-history "remote") "remote")))
+  (list "h1" "h2"))
+
+; ---------- federation: outbound partition ----------
+
+; bob (local), alice@remote + carol@remote (remote) follow star
+(define
+  Gf
+  (feed/follow-graph
+    (list
+      (list "bob" "star")
+      (list "alice@remote" "star")
+      (list "carol@remote" "star"))))
+(define
+  Sf
+  (feed/stream (list (feed/activity "star" "post" "s1" 1 (list)))))
+(define
+  remote?
+  (fn (id) (feed/-elem? id (list "alice@remote" "carol@remote"))))
+(define parts (feed/federate Sf Gf remote?))
+
+(feed-test "local deliveries" (feed/count (get parts :local)) 1)
+(feed-test "remote deliveries" (feed/count (get parts :remote)) 2)
+(feed-test
+  "local recipient is bob"
+  (feed/recipients (get parts :local))
+  (list "bob"))
+
+; deliver: send-fn receives each remote event, local inbox returned
+(define sent (list))
+(define send-fn (fn (to act) (set! sent (append sent (list to)))))
+(define local-inbox (feed/deliver Sf Gf remote? send-fn))
+(feed-test "deliver returns local inbox" (feed/count local-inbox) 1)
+(feed-test "deliver sent to both remotes" (len sent) 2)
+(feed-test "deliver remote targets" sent (list "alice@remote" "carol@remote"))
+
+; ---------- end-to-end: federated, ACL-filtered, ranked timeline ----------
+
+(define
+  base
+  (feed/stream
+    (list
+      (feed/normalize {:actor "alice" :object "a1" :at 100})
+      (feed/normalize {:actor "bob" :object "b1" :visible-to (list "carol") :at 90})
+      (feed/normalize {:actor "eve" :object "e1" :visible-to (list "dave") :at 80}))))
+(define federated (feed/inbound base (list {:actor "peer" :object "x1" :at 110})))
+(define rec (feed/recency 120 10))
+(define
+  carol-tl
+  (feed/timeline federated "carol" feed/permit-acl? rec 3))
+
+; eve's :visible-to excludes carol -> filtered out; peer/alice public, bob allows carol
+(feed-test "carol federated timeline count" (feed/count carol-tl) 3)
+(feed-test
+  "carol timeline order (recency)"
+  (map (fn (a) (get a :object)) (feed/items carol-tl))
+  (list "x1" "a1" "b1"))
+(feed-test
+  "eve dm excluded from carol"
+  (feed/-elem? "e1" (map (fn (a) (get a :object)) (feed/items carol-tl)))
+  false)
+(feed-test
+  "dave sees eve dm not bob"
+  (map
+    (fn (a) (get a :object))
+    (feed/items
+      (feed/timeline federated "dave" feed/permit-acl? rec 5)))
+  (list "x1" "a1" "e1"))

lib/feed/tests/mute.sx

@@ -0,0 +1,68 @@
+; Follow-up — viewer mute/block filtering. (feed-test name got expected)
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/normalize {:actor "alice" :object "P1" :at 1 :tags (list "news")})
+      (feed/normalize {:actor "bob" :object "P2" :at 2 :tags (list "spam")})
+      (feed/normalize {:actor "alice" :object "P3" :at 3 :tags (list "cats")})
+      (feed/normalize {:actor "carol" :object "P4" :at 4 :tags (list "news" "spam")}))))
+
+; ---------- mute actors ----------
+
+(feed-test
+  "mute bob drops his post"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/mute-actors S (list "bob"))))
+  (list "P1" "P3" "P4"))
+(feed-test
+  "mute alice drops two"
+  (feed/count (feed/mute-actors S (list "alice")))
+  2)
+(feed-test
+  "mute nobody keeps all"
+  (feed/count (feed/mute-actors S (list)))
+  4)
+
+; ---------- mute tags ----------
+
+(feed-test
+  "mute spam tag drops two"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/mute-tags S (list "spam"))))
+  (list "P1" "P3"))
+(feed-test
+  "mute news+cats leaves spam-only"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/mute-tags S (list "news" "cats"))))
+  (list "P2"))
+
+; ---------- mute objects ----------
+
+(feed-test
+  "mute object P3 (thread mute)"
+  (feed/count (feed/mute-objects S (list "P3")))
+  3)
+
+; ---------- combined prefs ----------
+
+(feed-test
+  "apply-prefs actors + tags"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/apply-prefs S {:mute-actors (list "bob") :mute-tags (list "cats")})))
+  (list "P1" "P4"))
+(feed-test
+  "apply-prefs empty keeps all"
+  (feed/count (feed/apply-prefs S {}))
+  4)
+(feed-test
+  "apply-prefs all three filters"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/apply-prefs S {:mute-objects (list "P3") :mute-actors (list "carol") :mute-tags (list "spam")})))
+  (list "P1"))

lib/feed/tests/notify.sx

@@ -0,0 +1,69 @@
+; Follow-up — notification feed over an inbox. (feed-test name got expected)
+
+; an inbox is a stream of {:to receiver :activity act} events
+(define mk-ev (fn (to act) {:activity act :to to}))
+
+(define
+  IB
+  (feed/stream
+    (list
+      (mk-ev "alice" (feed/activity "bob" "like" "P" 10 (list)))
+      (mk-ev "alice" (feed/activity "carol" "like" "P" 20 (list)))
+      (mk-ev "alice" (feed/activity "dave" "reply" "Q" 30 (list)))
+      (mk-ev "bob" (feed/activity "eve" "like" "R" 40 (list))))))
+
+; ---------- raw notifications ----------
+
+(feed-test
+  "alice notification count"
+  (feed/count (feed/notifications IB "alice"))
+  3)
+(feed-test
+  "bob notification count"
+  (feed/count (feed/notifications IB "bob"))
+  1)
+(feed-test
+  "zoe no notifications"
+  (feed/count (feed/notifications IB "zoe"))
+  0)
+
+; ---------- verb filtering ----------
+
+(feed-test
+  "alice likes only"
+  (feed/count (feed/notify-verbs IB "alice" (list "like")))
+  2)
+(feed-test
+  "alice replies only"
+  (feed/count (feed/notify-verbs IB "alice" (list "reply")))
+  1)
+(feed-test
+  "alice like+reply"
+  (feed/count (feed/notify-verbs IB "alice" (list "like" "reply")))
+  3)
+(feed-test
+  "alice follow (none)"
+  (feed/count (feed/notify-verbs IB "alice" (list "follow")))
+  0)
+
+; ---------- digest ----------
+
+(define dig (feed/notify-digest IB "alice"))
+
+(feed-test "digest group count" (len dig) 2)
+(feed-test
+  "digest sorted by key (like|P before reply|Q)"
+  (map (fn (g) (get g :object)) dig)
+  (list "P" "Q"))
+(feed-test
+  "like group actors"
+  (get (nth dig 0) :actors)
+  (list "bob" "carol"))
+(feed-test "like group count" (get (nth dig 0) :count) 2)
+(feed-test "like group verb" (get (nth dig 0) :verb) "like")
+(feed-test "reply group count" (get (nth dig 1) :count) 1)
+(feed-test
+  "reply group actors"
+  (get (nth dig 1) :actors)
+  (list "dave"))
+(feed-test "empty digest for zoe" (feed/notify-digest IB "zoe") (list))

lib/feed/tests/page.sx

@@ -0,0 +1,86 @@
+; Follow-up — pagination (offset + cursor). (feed-test name got expected)
+
+; ---------- offset / limit ----------
+
+(define
+  O
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "o1" 1 (list))
+      (feed/activity "u" "post" "o2" 2 (list))
+      (feed/activity "u" "post" "o3" 3 (list))
+      (feed/activity "u" "post" "o4" 4 (list))
+      (feed/activity "u" "post" "o5" 5 (list)))))
+
+(feed-test
+  "page 1"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/page O 0 2)))
+  (list "o1" "o2"))
+(feed-test
+  "page 2"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/page O 2 2)))
+  (list "o3" "o4"))
+(feed-test
+  "page 3 (partial)"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/page O 4 2)))
+  (list "o5"))
+(feed-test
+  "page past end empty"
+  (feed/count (feed/page O 10 2))
+  0)
+(feed-test "page-count 5/2 = 3" (feed/page-count O 2) 3)
+(feed-test "page-count 5/5 = 1" (feed/page-count O 5) 1)
+
+; ---------- cursor (recency) ----------
+
+(define
+  R
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "a" 50 (list))
+      (feed/activity "u" "post" "b" 40 (list))
+      (feed/activity "u" "post" "c" 30 (list))
+      (feed/activity "u" "post" "d" 20 (list))
+      (feed/activity "u" "post" "e" 10 (list)))))
+
+(define p1 (feed/page-before R 100 2))
+(feed-test
+  "cursor page 1 newest first"
+  (map (fn (a) (get a :object)) (feed/items p1))
+  (list "a" "b"))
+(feed-test "next cursor after page 1" (feed/next-cursor p1) 40)
+
+(define p2 (feed/page-before R (feed/next-cursor p1) 2))
+(feed-test
+  "cursor page 2"
+  (map (fn (a) (get a :object)) (feed/items p2))
+  (list "c" "d"))
+(feed-test "next cursor after page 2" (feed/next-cursor p2) 20)
+
+(define p3 (feed/page-before R (feed/next-cursor p2) 2))
+(feed-test
+  "cursor page 3 (partial)"
+  (map (fn (a) (get a :object)) (feed/items p3))
+  (list "e"))
+
+(feed-test
+  "empty page nil cursor"
+  (feed/next-cursor (feed/page-before R 5 2))
+  nil)
+
+(feed-test
+  "after cursor loads newer"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/recent (feed/after R 30))))
+  (list "a" "b"))
+(feed-test
+  "before cursor count"
+  (feed/count (feed/before R 30))
+  2)

lib/feed/tests/rank.sx

@@ -0,0 +1,160 @@
+; Phase 3 — aggregation + ranking. (feed-test name got expected)
+
+; ---------- aggregation ----------
+
+(define
+  A
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 5 (list))
+      (feed/activity "alice" "post" "p2" 15 (list))
+      (feed/activity "bob" "post" "p3" 25 (list))
+      (feed/activity "alice" "like" "p1" 35 (list)))))
+
+(feed-test "actor-counts" (feed/actor-counts A) {:alice 3 :bob 1})
+(feed-test "object-counts" (feed/object-counts A) {:p2 1 :p3 1 :p1 2})
+(feed-test
+  "group-by actor alice len"
+  (len (get (feed/group-by A feed/actor) "alice"))
+  3)
+(feed-test
+  "group-count empty"
+  (feed/group-count feed/empty feed/actor)
+  {})
+
+; day bucketing
+(define
+  D
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 5 (list))
+      (feed/activity "alice" "post" "p2" 8 (list))
+      (feed/activity "alice" "post" "p3" 12 (list)))))
+
+(feed-test "feed/day floor" (feed/day 12 10) 1)
+(feed-test "feed/day same bucket" (feed/day 8 10) 0)
+(feed-test "by-actor-day" (feed/by-actor-day D 10) {:alice#0 2 :alice#1 1})
+
+; ---------- recency ----------
+
+(define rec (feed/recency 100 10))
+(feed-test
+  "recency at=now -> 1"
+  (rec (feed/activity "x" "post" "o" 100 (list)))
+  1)
+(feed-test
+  "recency age=hl -> .5"
+  (rec (feed/activity "x" "post" "o" 90 (list)))
+  0.5)
+(feed-test
+  "recency age=2hl -> .25"
+  (rec (feed/activity "x" "post" "o" 80 (list)))
+  0.25)
+
+; ---------- velocity ----------
+
+(define vel (feed/velocity D 10))
+(feed-test
+  "velocity burst (at=12)"
+  (vel (feed/activity "alice" "post" "z" 12 (list)))
+  3)
+(feed-test
+  "velocity mid (at=8)"
+  (vel (feed/activity "alice" "post" "z" 8 (list)))
+  2)
+(feed-test
+  "velocity first (at=5)"
+  (vel (feed/activity "alice" "post" "z" 5 (list)))
+  1)
+(feed-test
+  "velocity other actor"
+  (vel (feed/activity "bob" "post" "z" 12 (list)))
+  0)
+
+; ---------- engagement ----------
+
+(define eng (feed/engagement A))
+(feed-test
+  "engagement p1"
+  (eng (feed/activity "x" "post" "p1" 0 (list)))
+  2)
+(feed-test
+  "engagement p2"
+  (eng (feed/activity "x" "post" "p2" 0 (list)))
+  1)
+
+; ---------- composite ----------
+
+(define
+  cmp1
+  (feed/composite (list (list 2 (fn (a) (get a :at))))))
+(feed-test
+  "composite single part"
+  (cmp1 (feed/activity "x" "post" "o" 5 (list)))
+  10)
+(define
+  cmp2
+  (feed/composite
+    (list
+      (list 2 (fn (a) (get a :at)))
+      (list 3 (fn (a) 1)))))
+(feed-test
+  "composite two parts"
+  (cmp2 (feed/activity "x" "post" "o" 5 (list)))
+  13)
+
+; ---------- ranking ----------
+
+(define
+  R
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "oC" 80 (list))
+      (feed/activity "u" "post" "oA" 100 (list))
+      (feed/activity "u" "post" "oB" 90 (list)))))
+
+(feed-test
+  "rank by recency objects"
+  (map (fn (a) (get a :object)) (feed/items (feed/rank R rec)))
+  (list "oA" "oB" "oC"))
+(feed-test
+  "top-2 by recency"
+  (map (fn (a) (get a :object)) (feed/items (feed/top R rec 2)))
+  (list "oA" "oB"))
+(feed-test "top-2 count" (feed/count (feed/top R rec 2)) 2)
+
+; constant score -> tiebreak by :at descending
+(define
+  T
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "f" 10 (list))
+      (feed/activity "u" "post" "g" 30 (list))
+      (feed/activity "u" "post" "h" 20 (list)))))
+(feed-test
+  "tiebreak at-desc"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/rank T (fn (a) 0))))
+  (list "g" "h" "f"))
+
+; equal score AND equal :at -> stable input order
+(define
+  E
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "first" 50 (list))
+      (feed/activity "u" "post" "second" 50 (list)))))
+(feed-test
+  "stable equal-key input order"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/rank E (fn (a) 0))))
+  (list "first" "second"))
+
+(feed-test
+  "with-scores attaches score"
+  (get (nth (feed/items (feed/with-scores R rec)) 1) :score)
+  1)
+
+(feed-test "rank preserves count" (feed/count (feed/rank A rec)) 4)

lib/feed/tests/thread.sx

@@ -0,0 +1,49 @@
+; Follow-up — conversation threading via :reply-to closure. (feed-test name got expected)
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/normalize {:actor "a" :object "root" :at 1})
+      (feed/normalize {:actor "b" :object "r1" :at 2 :verb "reply" :reply-to "root"})
+      (feed/normalize {:actor "c" :object "r2" :at 3 :verb "reply" :reply-to "root"})
+      (feed/normalize {:actor "d" :object "r3" :at 4 :verb "reply" :reply-to "r1"})
+      (feed/normalize {:actor "e" :object "x" :at 5}))))
+
+; ---------- direct replies ----------
+
+(feed-test "direct replies to root" (feed/reply-count S "root") 2)
+(feed-test "direct replies to r1" (feed/reply-count S "r1") 1)
+(feed-test "no replies to r3" (feed/reply-count S "r3") 0)
+(feed-test
+  "replies objects to root"
+  (map (fn (a) (get a :object)) (feed/items (feed/replies S "root")))
+  (list "r1" "r2"))
+
+; ---------- thread closure ----------
+
+(feed-test
+  "thread objects root (transitive)"
+  (feed/thread-objects S "root")
+  (list "root" "r1" "r2" "r3"))
+(feed-test
+  "thread root chronological"
+  (map (fn (a) (get a :object)) (feed/items (feed/thread S "root")))
+  (list "root" "r1" "r2" "r3"))
+(feed-test "thread size root" (feed/thread-size S "root") 4)
+(feed-test
+  "thread excludes unrelated x"
+  (feed/-elem?
+    "x"
+    (map (fn (a) (get a :object)) (feed/items (feed/thread S "root"))))
+  false)
+
+; ---------- sub-thread ----------
+
+(feed-test
+  "thread from r1 (sub-tree)"
+  (map (fn (a) (get a :object)) (feed/items (feed/thread S "r1")))
+  (list "r1" "r3"))
+(feed-test "thread size r1" (feed/thread-size S "r1") 2)
+(feed-test "leaf thread is itself" (feed/thread-size S "r3") 1)
+(feed-test "unrelated thread is itself" (feed/thread-size S "x") 1)

lib/feed/tests/trending.sx

@@ -0,0 +1,82 @@
+; Follow-up — trending objects/actors by recent activity. (feed-test name got expected)
+
+; window (50,100]: X@60,X@70 (a), Y@80 (b), Z@90 (c); W@40 is too old
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "a" "post" "X" 60 (list))
+      (feed/activity "a" "post" "X" 70 (list))
+      (feed/activity "b" "post" "Y" 80 (list))
+      (feed/activity "c" "post" "Z" 90 (list))
+      (feed/activity "d" "post" "W" 40 (list)))))
+
+; ---------- trending objects ----------
+
+(feed-test
+  "trending count (3 in window)"
+  (len (feed/trending S 100 50 10))
+  3)
+(feed-test
+  "trending top object"
+  (get
+    (nth (feed/trending S 100 50 10) 0)
+    :object)
+  "X")
+(feed-test
+  "trending top count"
+  (get
+    (nth (feed/trending S 100 50 10) 0)
+    :count)
+  2)
+(feed-test
+  "trending order (count desc, key asc tiebreak)"
+  (map
+    (fn (e) (get e :object))
+    (feed/trending S 100 50 10))
+  (list "X" "Y" "Z"))
+(feed-test
+  "trending top-2"
+  (map
+    (fn (e) (get e :object))
+    (feed/trending S 100 50 2))
+  (list "X" "Y"))
+(feed-test
+  "old object W excluded"
+  (feed/-elem?
+    "W"
+    (map
+      (fn (e) (get e :object))
+      (feed/trending S 100 50 10)))
+  false)
+(feed-test
+  "narrow window keeps only newest"
+  (map
+    (fn (e) (get e :object))
+    (feed/trending S 100 15 10))
+  (list "Z"))
+(feed-test
+  "empty window -> nothing"
+  (feed/trending S 100 5 10)
+  (list))
+
+; ---------- trending actors ----------
+
+(feed-test
+  "trending actor top"
+  (get
+    (nth (feed/trending-actors S 100 50 10) 0)
+    :actor)
+  "a")
+(feed-test
+  "trending actor count"
+  (get
+    (nth (feed/trending-actors S 100 50 10) 0)
+    :count)
+  2)
+(feed-test
+  "trending actors order"
+  (map
+    (fn (e) (get e :actor))
+    (feed/trending-actors S 100 50 10))
+  (list "a" "b" "c"))

lib/feed/thread.sx

@@ -0,0 +1,59 @@
+; feed/thread — conversation threading. A reply carries :reply-to <parent-object>
+; (normalize preserves it). A thread is the transitive closure over :reply-to from
+; a root object: root + replies + replies-to-replies, gathered chronologically.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem?, feed/-distinct).
+
+; direct replies to an object
+(define
+  feed/replies
+  (fn
+    (stream object)
+    (feed/filter stream (fn (a) (equal? (get a :reply-to) object)))))
+
+(define
+  feed/reply-count
+  (fn (stream object) (feed/count (feed/replies stream object))))
+
+; iterate f from x until the result stops growing (set-closure fixpoint)
+(define
+  feed/-fixpoint
+  (fn
+    (f x)
+    (let
+      ((nx (f x)))
+      (if (= (len nx) (len x)) x (feed/-fixpoint f nx)))))
+
+; the set of object-ids in the thread rooted at `root`
+(define
+  feed/thread-objects
+  (fn
+    (stream root)
+    (let
+      ((all (feed/items stream)))
+      (feed/-fixpoint
+        (fn
+          (acc)
+          (feed/-distinct
+            (append
+              acc
+              (map
+                (fn (a) (get a :object))
+                (filter (fn (a) (feed/-elem? (get a :reply-to) acc)) all)))))
+        (list root)))))
+
+; the full thread as a chronological stream (root + all descendants)
+(define
+  feed/thread
+  (fn
+    (stream root)
+    (let
+      ((objs (feed/thread-objects stream root)))
+      (feed/sort-by-at
+        (feed/filter stream (fn (a) (feed/-elem? (get a :object) objs)))))))
+
+; how many activities are in the thread (root counts as 1)
+(define
+  feed/thread-size
+  (fn (stream root) (feed/count (feed/thread stream root))))

lib/feed/trending.sx

@@ -0,0 +1,42 @@
+; feed/trending — what's hot right now: objects (or actors) ranked by activity
+; count within a recency window. Deterministic: count descending, ties broken by
+; key ascending (entries are pre-sorted by key, then stable grade-down by count).
+;
+; Requires: lib/feed/stream.sx, lib/feed/aggregate.sx (object/actor-counts),
+; lib/feed/rank.sx (feed/-desc-by).
+
+; activities within (now-window, now]
+(define
+  feed/-recent
+  (fn
+    (stream now window)
+    (feed/filter
+      stream
+      (fn (a) (and (<= (get a :at) now) (> (get a :at) (- now window)))))))
+
+; counts dict -> top-N entries {label key, :count n}, count desc, key asc
+(define
+  feed/-top-counts
+  (fn
+    (counts label n)
+    (let
+      ((entries (map (fn (k) (assoc {:count (get counts k)} label k)) (sort (keys counts)))))
+      (take (feed/-desc-by entries (fn (e) (get e :count))) n))))
+
+; top-N trending objects in the window
+(define
+  feed/trending
+  (fn
+    (stream now window n)
+    (feed/-top-counts
+      (feed/object-counts (feed/-recent stream now window))
+      :object n)))
+
+; top-N most active actors in the window
+(define
+  feed/trending-actors
+  (fn
+    (stream now window n)
+    (feed/-top-counts
+      (feed/actor-counts (feed/-recent stream now window))
+      :actor n)))

lib/search/api.sx

@@ -0,0 +1,24 @@
+;; search public API — assembles the canonical Haskell source from all layers.
+;; Tests and callers concatenate `search/src` with their own top-level bindings
+;; (e.g. "result = lookupTerm \"cat\" idx\n") and evaluate via the haskell-on-sx
+;; interpreter. Public Haskell entry points: indexDoc, lookupTerm, deleteDoc,
+;; docFreq, allTerms, tokens, positioned, evalQuery, parseQuery, searchQuery,
+;; rankTfIdf, rankBm25, topNTfIdf, topNBm25, fedIndex, aclFilter, searchTfIdfAcl,
+;; topNTfIdfAcl, searchBm25Acl, prefixTerms, prefixDocs, prefixRankTfIdf.
+
+(define
+  search/src
+  (str
+    search/tokenize-src
+    "\n"
+    search/index-src
+    "\n"
+    search/query-src
+    "\n"
+    search/parse-src
+    "\n"
+    search/rank-src
+    "\n"
+    search/fed-src
+    "\n"
+    search/prefix-src))

lib/search/conformance.conf

@@ -0,0 +1,39 @@
+# search-on-sx conformance config — sourced by lib/guest/conformance.sh.
+
+LANG_NAME=search
+SCOREBOARD_DIR=lib/search
+MODE=counters
+COUNTERS_PASS=hk-test-pass
+COUNTERS_FAIL=hk-test-fail
+TIMEOUT_PER_SUITE=600
+
+PRELOADS=(
+  lib/haskell/tokenizer.sx
+  lib/haskell/layout.sx
+  lib/haskell/parser.sx
+  lib/haskell/desugar.sx
+  lib/haskell/runtime.sx
+  lib/haskell/match.sx
+  lib/haskell/eval.sx
+  lib/haskell/map.sx
+  lib/haskell/set.sx
+  lib/haskell/testlib.sx
+  lib/search/tokenize.sx
+  lib/search/index.sx
+  lib/search/query.sx
+  lib/search/parse.sx
+  lib/search/rank.sx
+  lib/search/fed.sx
+  lib/search/prefix.sx
+  lib/search/api.sx
+  lib/search/testlib.sx
+)
+
+SUITES=(
+  "index:lib/search/tests/index.sx"
+  "boolean:lib/search/tests/boolean.sx"
+  "parse:lib/search/tests/parse.sx"
+  "rank:lib/search/tests/rank.sx"
+  "integration:lib/search/tests/integration.sx"
+  "prefix:lib/search/tests/prefix.sx"
+)

lib/search/conformance.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+# Thin wrapper — see lib/guest/conformance.sh and lib/search/conformance.conf.
+exec bash "$(dirname "$0")/../guest/conformance.sh" "$(dirname "$0")/conformance.conf" "$@"

lib/search/fed.sx

@@ -0,0 +1,16 @@
+;; search federation + ACL — Haskell source fragment. Depends on index + rank.
+;; Federation merges per-peer INDICES (not ranked results): each peer's local
+;; DocIds are relabelled to global ids `gid peer local = peer*1000 + local`
+;; (dedupe by (peer,doc-id) is automatic via the bijection), then posting lists
+;; are unioned per term. Ranking then runs once over the merged index, which is
+;; rank-correct. ACL is a post-rank filter: an injected `permit :: DocId -> Bool`
+;; predicate (viewer baked in by the caller) — never baked into the index.
+;;   fedIndex       :: [(PeerId, Index)] -> Index
+;;   aclFilter      :: (DocId -> Bool) -> [DocId] -> [DocId]
+;;   searchTfIdfAcl :: (DocId -> Bool) -> [Term] -> Index -> [DocId]
+;;   topNTfIdfAcl   :: Int -> (DocId -> Bool) -> [Term] -> Index -> [DocId]
+;;   searchBm25Acl  :: (DocId -> Bool) -> Float -> Float -> [Term] -> Index -> [DocId]
+
+(define
+  search/fed-src
+  "gid peer local = peer * 1000 + local\nfedRelabelPosting peer p = (gid peer (fst p), snd p)\nfedRelabelEntry peer e = (fst e, map (fedRelabelPosting peer) (snd e))\nfedRelabelIndex peer idx = map (fedRelabelEntry peer) idx\nfedInsP p [] = [p]\nfedInsP p (q:qs) = if fst p < fst q then p : q : qs else if fst p == fst q then p : qs else q : fedInsP p qs\nfedMergePL a b = foldr fedInsP b a\nfedInsTerm t pl [] = [(t, pl)]\nfedInsTerm t pl (x:xs) = if t < fst x then (t, pl) : x : xs else if t == fst x then (fst x, fedMergePL pl (snd x)) : xs else x : fedInsTerm t pl xs\nfedMergeEntry idx e = fedInsTerm (fst e) (snd e) idx\nfedMergeTwo a b = foldl fedMergeEntry a b\nfedAddPeer acc pair = fedMergeTwo acc (fedRelabelIndex (fst pair) (snd pair))\nfedIndex pairs = foldl fedAddPeer emptyIndex pairs\naclFilter permit docs = filter permit docs\nsearchTfIdfAcl permit ts idx = aclFilter permit (rankTfIdf ts idx)\ntopNTfIdfAcl n permit ts idx = take n (aclFilter permit (rankTfIdf ts idx))\nsearchBm25Acl permit k1 b ts idx = aclFilter permit (rankBm25 k1 b ts idx)\n")

lib/search/index.sx

@@ -0,0 +1,15 @@
+;; search inverted index — Haskell source fragment (depends on tokenize).
+;; Index = [(Term, [(DocId, [Pos])])], sorted by Term; postings sorted by DocId.
+;; Data.Map's public API lacks toList/keys/map/filter, so a sorted assoc-list
+;; index is used — it is the conceptual `Map Term [(DocId,[Pos])]` and exposes
+;; term iteration (allTerms) and df naturally for ranking.
+;;   emptyIndex :: Index
+;;   indexDoc   :: DocId -> String -> Index -> Index   (re-index replaces)
+;;   lookupTerm :: Term -> Index -> [(DocId, [Pos])]
+;;   deleteDoc  :: DocId -> Index -> Index
+;;   docFreq    :: Term -> Index -> Int
+;;   allTerms   :: Index -> [Term]
+
+(define
+  search/index-src
+  "emptyIndex = []\ngroupBump [] t p = [(t, [p])]\ngroupBump (g:gs) t p = if fst g == t then (t, snd g ++ [p]) : gs else g : groupBump gs t p\ngroupStep acc tp = groupBump acc (fst tp) (snd tp)\ngroupTok pairs = foldl groupStep [] pairs\ninsPosting d ps [] = [(d, ps)]\ninsPosting d ps (q:qs) = if d < fst q then (d, ps) : q : qs else if d == fst q then (d, ps) : qs else q : insPosting d ps qs\ninsTerm t d ps [] = [(t, [(d, ps)])]\ninsTerm t d ps (e:es) = if t < fst e then (t, [(d, ps)]) : e : es else if t == fst e then (fst e, insPosting d ps (snd e)) : es else e : insTerm t d ps es\nindexStep d ix tp = insTerm (fst tp) d (snd tp) ix\nindexDoc d text idx = foldl (indexStep d) idx (groupTok (positioned text))\nlookupTerm t idx = case lookup t idx of { Nothing -> []; Just pl -> pl }\ndocFreq t idx = length (lookupTerm t idx)\nallTerms idx = map fst idx\npostingKeep d q = fst q /= d\ndropTermDoc d e = (fst e, filter (postingKeep d) (snd e))\nplKeep e = not (null (snd e))\ndeleteDoc d idx = filter plKeep (map (dropTermDoc d) idx)\n")

lib/search/parse.sx

@@ -0,0 +1,18 @@
+;; search query parser — Haskell source fragment. Depends on tokenize + query.
+;; Grammar (precedence OR < AND < NOT):
+;;   expr   = orExpr
+;;   orExpr = andExpr (OR andExpr)*
+;;   andExpr= notExpr ((AND | <implicit>) notExpr)*   -- adjacency means AND
+;;   notExpr= NOT notExpr | atom
+;;   atom   = '(' expr ')' | '"' word+ '"' | word
+;; Keywords AND/OR/NOT are case-insensitive; bare words are normalized via tokens.
+;; Gotchas: delimiters matched by ord (escaped char literals like '\"' break the
+;; haskell-on-sx tokenizer); an [] *pattern* inside a `case` alt also breaks the
+;; parser, so qNormTerm/qDropRP/showQ are written as multi-clause functions.
+;;   parseQuery  :: String -> Query
+;;   searchQuery :: String -> Index -> [DocId]
+;;   showQ       :: Query -> String   -- canonical render for tests/debug
+
+(define
+  search/parse-src
+  "data QTok = TAnd | TOr | TNot | TLP | TRP | TWord String | TPhrase [String]\nqIsSpace c = ord c == 32\nqIsLP c = ord c == 40\nqIsRP c = ord c == 41\nqIsQuote c = ord c == 34\nqDelim c = qIsSpace c || qIsLP c || qIsRP c || qIsQuote c\nqReadWord [] = ([], [])\nqReadWord (c:cs) = if qDelim c then ([], c:cs) else let (w, rest) = qReadWord cs in (c:w, rest)\nqReadPhrase [] = ([], [])\nqReadPhrase (c:cs) = if qIsQuote c then ([], cs) else let (w, rest) = qReadPhrase cs in (c:w, rest)\ntoUpperCh c = chr (toUpper (ord c))\nqUpper w = joinChars (map toUpperCh w)\nqFirstTok [] = \"\"\nqFirstTok (x:xs) = x\nqNormTerm w = qFirstTok (tokens w)\nqClassify w = if qUpper w == \"AND\" then TAnd else if qUpper w == \"OR\" then TOr else if qUpper w == \"NOT\" then TNot else TWord (qNormTerm w)\nqPhraseTok cs = let (p, rest) = qReadPhrase cs in TPhrase (tokens p) : qtokens rest\nqWordTok cs = let (w, rest) = qReadWord cs in qClassify w : qtokens rest\nqtokens [] = []\nqtokens (c:cs) = if qIsSpace c then qtokens cs else if qIsLP c then TLP : qtokens cs else if qIsRP c then TRP : qtokens cs else if qIsQuote c then qPhraseTok cs else qWordTok (c:cs)\nqDropRP (q, (TRP:rest)) = (q, rest)\nqDropRP (q, ts) = (q, ts)\nparseAtom [] = (Term \"\", [])\nparseAtom (TLP:ts) = qDropRP (parseExpr ts)\nparseAtom (TPhrase ps : ts) = (Phrase ps, ts)\nparseAtom (TWord w : ts) = (Term w, ts)\nparseAtom ts = (Term \"\", ts)\nqWrapNot (q, ts) = (Not q, ts)\nparseNot (TNot:ts) = qWrapNot (parseNot ts)\nparseNot ts = parseAtom ts\nqStartsAtom (TWord w : ts) = True\nqStartsAtom (TPhrase p : ts) = True\nqStartsAtom (TLP : ts) = True\nqStartsAtom (TNot : ts) = True\nqStartsAtom ts = False\nqAndStep left ts = let (r, rest) = parseNot ts in parseAndR (And left r) rest\nparseAndR left (TAnd:ts) = qAndStep left ts\nparseAndR left ts = if qStartsAtom ts then qAndStep left ts else (left, ts)\nparseAnd ts = let (l, rest) = parseNot ts in parseAndR l rest\nparseOrR left (TOr:ts) = let (r, rest) = parseAnd ts in parseOrR (Or left r) rest\nparseOrR left ts = (left, ts)\nparseExpr ts = let (l, rest) = parseAnd ts in parseOrR l rest\nparseQuery s = fst (parseExpr (qtokens s))\nsearchQuery s idx = evalQuery idx (parseQuery s)\njoinSp [] = \"\"\njoinSp [x] = x\njoinSp (x:xs) = x ++ \"-\" ++ joinSp xs\nshowQ (Term t) = \"T:\" ++ t\nshowQ (And a b) = \"(\" ++ showQ a ++ \" & \" ++ showQ b ++ \")\"\nshowQ (Or a b) = \"(\" ++ showQ a ++ \" | \" ++ showQ b ++ \")\"\nshowQ (Not a) = \"!\" ++ showQ a\nshowQ (Phrase ts) = \"P:\" ++ joinSp ts\n")

lib/search/prefix.sx

@@ -0,0 +1,10 @@
+;; search prefix / wildcard queries — Haskell source fragment. Depends on index +
+;; rank (reuses candStep / rankTfIdf). A prefix matches every indexed term that
+;; starts with it; the matching terms are unioned (OR) into a docid set.
+;;   prefixTerms     :: String -> Index -> [Term]      (sorted, from allTerms)
+;;   prefixDocs      :: String -> Index -> [DocId]     (sorted union)
+;;   prefixRankTfIdf :: String -> Index -> [DocId]     (ranked by the matched terms)
+
+(define
+  search/prefix-src
+  "prefixTerms pre idx = filter (isPrefixOf pre) (allTerms idx)\nprefixDocs pre idx = foldl (candStep idx) [] (prefixTerms pre idx)\nprefixRankTfIdf pre idx = rankTfIdf (prefixTerms pre idx) idx\n")

lib/search/query.sx

@@ -0,0 +1,11 @@
+;; search query AST + boolean/phrase evaluation — Haskell source fragment.
+;; Depends on tokenize + index.
+;;   data Query = Term String | And Query Query | Or Query Query
+;;              | Not Query | Phrase [String]
+;;   evalQuery :: Index -> Query -> [DocId]   (sorted, unique)
+;; Boolean ops are linear merges over docid-sorted posting lists; Not uses
+;; allDocs as the universe; Phrase checks positional adjacency.
+
+(define
+  search/query-src
+  "data Query = Term String | And Query Query | Or Query Query | Not Query | Phrase [String]\ndocsWith t idx = map fst (lookupTerm t idx)\nsortedUnion [] ys = ys\nsortedUnion xs [] = xs\nsortedUnion (x:xs) (y:ys) = if x < y then x : sortedUnion xs (y:ys) else if x > y then y : sortedUnion (x:xs) ys else x : sortedUnion xs ys\nsortedInter [] ys = []\nsortedInter xs [] = []\nsortedInter (x:xs) (y:ys) = if x < y then sortedInter xs (y:ys) else if x > y then sortedInter (x:xs) ys else x : sortedInter xs ys\nsortedDiff [] ys = []\nsortedDiff xs [] = xs\nsortedDiff (x:xs) (y:ys) = if x < y then x : sortedDiff xs (y:ys) else if x > y then sortedDiff (x:xs) ys else sortedDiff xs ys\nmergeDocs acc e = sortedUnion acc (map fst (snd e))\nallDocs idx = foldl mergeDocs [] idx\nposIn t d idx = case lookup d (lookupTerm t idx) of { Nothing -> []; Just ps -> ps }\nelemSorted x [] = False\nelemSorted x (y:ys) = if x == y then True else if x < y then False else elemSorted x ys\nphraseAtAll [] d idx p i = True\nphraseAtAll (t:ts) d idx p i = if elemSorted (p + i) (posIn t d idx) then phraseAtAll ts d idx p (i + 1) else False\nphraseStartsAt ts d idx p = phraseAtAll ts d idx p 0\nphraseInDoc [] d idx = True\nphraseInDoc (t0:rest) d idx = any (phraseStartsAt (t0:rest) d idx) (posIn t0 d idx)\nphraseHere ts idx d = phraseInDoc ts d idx\ninterStep idx acc tt = sortedInter acc (docsWith tt idx)\nphraseCands [] idx = allDocs idx\nphraseCands (t:ts) idx = foldl (interStep idx) (docsWith t idx) ts\nphraseDocs ts idx = filter (phraseHere ts idx) (phraseCands ts idx)\nevalQuery idx q = case q of { Term t -> docsWith t idx ; And a b -> sortedInter (evalQuery idx a) (evalQuery idx b) ; Or a b -> sortedUnion (evalQuery idx a) (evalQuery idx b) ; Not a -> sortedDiff (allDocs idx) (evalQuery idx a) ; Phrase ts -> phraseDocs ts idx }\n")

lib/search/rank.sx

@@ -0,0 +1,14 @@
+;; search ranking — Haskell source fragment. Depends on tokenize + index + query.
+;; Ranked retrieval over the candidate set (docs containing any query term).
+;; Scores are floats; ties broken by DocId ascending (deterministic).
+;;   numDocs    :: Index -> Int
+;;   docFreq    :: Term -> Index -> Int           (from index)
+;;   docLen     :: DocId -> Index -> Int
+;;   rankTfIdf  :: [Term] -> Index -> [DocId]
+;;   topNTfIdf  :: Int -> [Term] -> Index -> [DocId]
+;;   rankBm25   :: Float -> Float -> [Term] -> Index -> [DocId]   (k1, b)
+;;   topNBm25   :: Int -> Float -> Float -> [Term] -> Index -> [DocId]
+
+(define
+  search/rank-src
+  "numDocs idx = length (allDocs idx)\ntfIn t d idx = length (posIn t d idx)\nqIdf n df = if df == 0 then 0 else log (n / df)\nidf t idx = qIdf (numDocs idx) (docFreq t idx)\ntermScoreTf idx d t = tfIn t d idx * idf t idx\ntfidfDoc ts idx d = sum (map (termScoreTf idx d) ts)\ncandStep idx acc t = sortedUnion acc (docsWith t idx)\ncandDocs ts idx = foldl (candStep idx) [] ts\ncmpScore p1 p2 = if fst p1 > fst p2 then LT else if fst p1 < fst p2 then GT else compare (snd p1) (snd p2)\nmkPair f ts idx d = (f ts idx d, d)\nrankWith f ts idx = map snd (sortBy cmpScore (map (mkPair f ts idx) (candDocs ts idx)))\nrankTfIdf ts idx = rankWith tfidfDoc ts idx\ntopNTfIdf n ts idx = take n (rankTfIdf ts idx)\ntfAt d idx t = tfIn t d idx\ndocLen d idx = sum (map (tfAt d idx) (allTerms idx))\nlenAt idx d = docLen d idx\navgDocLen idx = sum (map (lenAt idx) (allDocs idx)) / numDocs idx\nbm25idf t idx = log ((numDocs idx - docFreq t idx + 0.5) / (docFreq t idx + 0.5) + 1)\nbm25Term k1 b avgdl idx d t = bm25idf t idx * (tfIn t d idx * (k1 + 1)) / (tfIn t d idx + k1 * (1 - b + b * docLen d idx / avgdl))\nbm25Doc k1 b ts idx d = sum (map (bm25Term k1 b (avgDocLen idx) idx d) ts)\nrankBm25 k1 b ts idx = rankWith (bm25Doc k1 b) ts idx\ntopNBm25 n k1 b ts idx = take n (rankBm25 k1 b ts idx)\n")

lib/search/scoreboard.json

@@ -0,0 +1,15 @@
+{
+  "lang": "search",
+  "total_passed": 136,
+  "total_failed": 0,
+  "total": 136,
+  "suites": [
+    {"name":"index","passed":18,"failed":0,"total":18},
+    {"name":"boolean","passed":28,"failed":0,"total":28},
+    {"name":"parse","passed":32,"failed":0,"total":32},
+    {"name":"rank","passed":23,"failed":0,"total":23},
+    {"name":"integration","passed":21,"failed":0,"total":21},
+    {"name":"prefix","passed":14,"failed":0,"total":14}
+  ],
+  "generated": "2026-06-06T20:21:41+00:00"
+}

lib/search/scoreboard.md

@@ -0,0 +1,12 @@
+# search scoreboard
+
+**136 / 136 passing** (0 failure(s)).
+
+| Suite | Passed | Total | Status |
+|-------|--------|-------|--------|
+| index | 18 | 18 | ok |
+| boolean | 28 | 28 | ok |
+| parse | 32 | 32 | ok |
+| rank | 23 | 23 | ok |
+| integration | 21 | 21 | ok |
+| prefix | 14 | 14 | ok |

lib/search/testlib.sx

@@ -0,0 +1,50 @@
+;; search test helpers — convert forced haskell values to plain SX and run
+;; programs built on top of search/src. Reuses hk-test / counters from
+;; lib/haskell/testlib.sx (preloaded by the conformance config).
+
+;; Recursively turn a forced HK value into plain SX:
+;;   cons-list  -> SX list,  Tuple -> SX list,  leaves unchanged.
+(define
+  search-hk->sx
+  (fn
+    (v)
+    (cond
+      ((and (list? v) (not (empty? v)) (= (first v) "[]")) (list))
+      ((and (list? v) (not (empty? v)) (= (first v) ":"))
+        (cons
+          (search-hk->sx (nth v 1))
+          (search-hk->sx (nth v 2))))
+      ((and (list? v) (not (empty? v)) (= (first v) "Tuple"))
+        (map search-hk->sx (rest v)))
+      (:else v))))
+
+;; Evaluate `extra` (extra top-level Haskell bindings) on top of search/src
+;; and return binding `name` as plain SX.
+(define
+  search-eval
+  (fn
+    (extra name)
+    (search-hk->sx
+      (hk-deep-force
+        (get (hk-eval-program (hk-core (str search/src extra))) name)))))
+
+(define
+  search-join
+  (fn
+    (sep xs)
+    (cond
+      ((empty? xs) "")
+      ((empty? (rest xs)) (first xs))
+      (:else (str (first xs) sep (search-join sep (rest xs)))))))
+
+;; Batch many haskell expressions into ONE program evaluation (amortizes the
+;; cost of parsing/binding search/src — important under heavy CPU load).
+;; `setup` is extra top-level Haskell; `exprs` is a list of expression strings
+;; whose results form a single haskell list. Returns the SX list of results.
+(define
+  search-batch
+  (fn
+    (setup exprs)
+    (search-eval
+      (str setup "\nresult = [" (search-join ", " exprs) "]\n")
+      "result")))

lib/search/tests/boolean.sx

@@ -0,0 +1,123 @@
+;; Phase 2 — query AST + boolean/phrase evaluation (hand-built Query values).
+;; Corpus:
+;;   doc 1 "the quick brown dog"   -> the quick brown dog
+;;   doc 2 "a quick brown fox"     -> a quick brown fox
+;;   doc 3 "the dog barks loudly"  -> the dog barks loudly
+;; All queries run in ONE program evaluation (search-batch) to stay fast.
+
+(define
+  search-corpus
+  "idx = indexDoc 3 \"the dog barks loudly\" (indexDoc 2 \"a quick brown fox\" (indexDoc 1 \"the quick brown dog\" emptyIndex))\n")
+
+(define
+  bool-cases
+  (list
+    (list
+      "term in two docs"
+      "evalQuery idx (Term \"quick\")"
+      (list 1 2))
+    (list
+      "term in two docs (the)"
+      "evalQuery idx (Term \"the\")"
+      (list 1 3))
+    (list "term in one doc" "evalQuery idx (Term \"fox\")" (list 2))
+    (list "term absent" "evalQuery idx (Term \"zzz\")" (list))
+    (list
+      "term case-sensitive at AST level"
+      "evalQuery idx (Term \"QUICK\")"
+      (list))
+    (list "term on empty index" "evalQuery emptyIndex (Term \"cat\")" (list))
+    (list
+      "and both terms"
+      "evalQuery idx (And (Term \"quick\") (Term \"brown\"))"
+      (list 1 2))
+    (list
+      "and overlap subset"
+      "evalQuery idx (And (Term \"the\") (Term \"dog\"))"
+      (list 1 3))
+    (list
+      "and disjoint is empty"
+      "evalQuery idx (And (Term \"the\") (Term \"fox\"))"
+      (list))
+    (list
+      "and right-nested"
+      "evalQuery idx (And (Term \"the\") (And (Term \"dog\") (Term \"barks\")))"
+      (list 3))
+    (list
+      "or two singletons"
+      "evalQuery idx (Or (Term \"fox\") (Term \"barks\"))"
+      (list 2 3))
+    (list
+      "or all docs"
+      "evalQuery idx (Or (Term \"quick\") (Term \"the\"))"
+      (list 1 2 3))
+    (list
+      "or with absent term"
+      "evalQuery idx (Or (Term \"fox\") (Term \"zzz\"))"
+      (list 2))
+    (list "not term" "evalQuery idx (Not (Term \"the\"))" (list 2))
+    (list "not term 2" "evalQuery idx (Not (Term \"quick\"))" (list 3))
+    (list
+      "and with not"
+      "evalQuery idx (And (Term \"quick\") (Not (Term \"the\")))"
+      (list 2))
+    (list
+      "double negation"
+      "evalQuery idx (Not (Not (Term \"fox\")))"
+      (list 2))
+    (list
+      "or of and with term"
+      "evalQuery idx (Or (And (Term \"the\") (Term \"dog\")) (Term \"fox\"))"
+      (list 1 2 3))
+    (list
+      "phrase adjacent both docs"
+      "evalQuery idx (Phrase [\"quick\", \"brown\"])"
+      (list 1 2))
+    (list
+      "phrase adjacent one doc"
+      "evalQuery idx (Phrase [\"brown\", \"dog\"])"
+      (list 1))
+    (list
+      "phrase the quick"
+      "evalQuery idx (Phrase [\"the\", \"quick\"])"
+      (list 1))
+    (list
+      "phrase dog barks"
+      "evalQuery idx (Phrase [\"dog\", \"barks\"])"
+      (list 3))
+    (list
+      "phrase non-adjacent empty"
+      "evalQuery idx (Phrase [\"quick\", \"dog\"])"
+      (list))
+    (list
+      "phrase order matters"
+      "evalQuery idx (Phrase [\"brown\", \"quick\"])"
+      (list))
+    (list
+      "phrase single term"
+      "evalQuery idx (Phrase [\"dog\"])"
+      (list 1 3))
+    (list
+      "phrase three terms"
+      "evalQuery idx (Phrase [\"the\", \"dog\", \"barks\"])"
+      (list 3))
+    (list
+      "and of phrase and term"
+      "evalQuery idx (And (Phrase [\"quick\", \"brown\"]) (Term \"dog\"))"
+      (list 1))
+    (list
+      "not of phrase"
+      "evalQuery idx (Not (Phrase [\"quick\", \"brown\"]))"
+      (list 3))))
+
+(define
+  bool-results
+  (search-batch search-corpus (map (fn (c) (nth c 1)) bool-cases)))
+
+(map-indexed
+  (fn
+    (i c)
+    (hk-test (nth c 0) (nth bool-results i) (nth c 2)))
+  bool-cases)
+
+{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}

lib/search/tests/index.sx

@@ -0,0 +1,88 @@
+;; Phase 1 — tokenize + inverted index.
+;; All cases run in ONE program evaluation (search-batch) to stay fast under load.
+;; Scalar results (docFreq) are wrapped as singleton lists so the batch is a list
+;; of lists.
+
+(define
+  index-cases
+  (list
+    (list
+      "tokens basic lowercases"
+      "tokens \"The Cat sat\""
+      (list "the" "cat" "sat"))
+    (list
+      "tokens strips punctuation"
+      "tokens \"Hello, World!\""
+      (list "hello" "world"))
+    (list "tokens collapses whitespace" "tokens \"  a   b  \"" (list "a" "b"))
+    (list "tokens empty is empty" "tokens \"\"" (list))
+    (list "tokens keeps digits" "tokens \"abc123 x9\"" (list "abc123" "x9"))
+    (list
+      "positioned attaches ordinals"
+      "positioned \"a b a\""
+      (list
+        (list "a" 0)
+        (list "b" 1)
+        (list "a" 2)))
+    (list
+      "index + lookup single doc"
+      "lookupTerm \"cat\" (indexDoc 1 \"the cat sat\" emptyIndex)"
+      (list (list 1 (list 1))))
+    (list
+      "lookup missing term is empty"
+      "lookupTerm \"dog\" (indexDoc 1 \"the cat sat\" emptyIndex)"
+      (list))
+    (list
+      "lookup records all positions"
+      "lookupTerm \"the\" (indexDoc 1 \"the cat the dog the\" emptyIndex)"
+      (list (list 1 (list 0 2 4))))
+    (list
+      "multi-doc posting list sorted by docid"
+      "lookupTerm \"x\" (indexDoc 1 \"x y\" (indexDoc 2 \"x z\" emptyIndex))"
+      (list
+        (list 1 (list 0))
+        (list 2 (list 0))))
+    (list
+      "index/query case symmetry"
+      "lookupTerm \"cat\" (indexDoc 1 \"CAT Cat cat\" emptyIndex)"
+      (list (list 1 (list 0 1 2))))
+    (list
+      "re-index replaces a doc"
+      "lookupTerm \"a\" (indexDoc 1 \"a a a\" (indexDoc 1 \"a\" emptyIndex))"
+      (list (list 1 (list 0 1 2))))
+    (list
+      "delete removes a doc"
+      "lookupTerm \"cat\" (deleteDoc 1 (indexDoc 1 \"the cat\" emptyIndex))"
+      (list))
+    (list
+      "delete leaves other docs"
+      "lookupTerm \"cat\" (deleteDoc 2 (indexDoc 2 \"big cat\" (indexDoc 1 \"the cat\" emptyIndex)))"
+      (list (list 1 (list 1))))
+    (list
+      "docFreq counts docs"
+      "[docFreq \"cat\" (indexDoc 2 \"a cat\" (indexDoc 1 \"the cat\" emptyIndex))]"
+      (list 2))
+    (list
+      "docFreq zero for missing"
+      "[docFreq \"zzz\" (indexDoc 1 \"a b\" emptyIndex)]"
+      (list 0))
+    (list
+      "allTerms sorted and unique"
+      "allTerms (indexDoc 1 \"banana apple cherry apple\" emptyIndex)"
+      (list "apple" "banana" "cherry"))
+    (list
+      "allTerms merged across docs"
+      "allTerms (indexDoc 2 \"d a\" (indexDoc 1 \"c b\" emptyIndex))"
+      (list "a" "b" "c" "d"))))
+
+(define
+  index-results
+  (search-batch "" (map (fn (c) (nth c 1)) index-cases)))
+
+(map-indexed
+  (fn
+    (i c)
+    (hk-test (nth c 0) (nth index-results i) (nth c 2)))
+  index-cases)
+
+{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}

lib/search/tests/integration.sx

@@ -0,0 +1,102 @@
+;; Phase 4 — federation (merge per-peer indices) + ACL post-filter.
+;; Peers (global id = peer*1000 + local):
+;;   peer 1: 1 "alpha beta"  2 "alpha gamma"     -> 1001 1002
+;;   peer 2: 1 "alpha delta" 2 "beta gamma"      -> 2001 2002
+;; ACL predicates are injected (viewer baked in by the caller), applied post-rank.
+
+(define
+  fed-setup
+  "p1 = indexDoc 2 \"alpha gamma\" (indexDoc 1 \"alpha beta\" emptyIndex)\np2 = indexDoc 2 \"beta gamma\" (indexDoc 1 \"alpha delta\" emptyIndex)\nfed = fedIndex [(1, p1), (2, p2)]\npermitP1 g = g < 2000\npermitNone g = False\npermitList g = elem g [1002, 2001]\n")
+
+(define
+  fed-cases
+  (list
+    (list
+      "fed merges all docs"
+      "sort (allDocs fed)"
+      (list 1001 1002 2001 2002))
+    (list
+      "fed docFreq across peers"
+      "[docFreq \"alpha\" fed]"
+      (list 3))
+    (list "fed docFreq beta" "[docFreq \"beta\" fed]" (list 2))
+    (list "fed numDocs" "[numDocs fed]" (list 4))
+    (list
+      "fed term lookup spans peers"
+      "map fst (lookupTerm \"gamma\" fed)"
+      (list 1002 2002))
+    (list
+      "fed preserves positions"
+      "lookupTerm \"beta\" fed"
+      (list
+        (list 1001 (list 1))
+        (list 2002 (list 0))))
+    (list
+      "fed rank alpha tie by gid"
+      "rankTfIdf [\"alpha\"] fed"
+      (list 1001 1002 2001))
+    (list
+      "fed rank beta"
+      "rankTfIdf [\"beta\"] fed"
+      (list 1001 2002))
+    (list
+      "fed boolean and"
+      "searchQuery \"alpha AND beta\" fed"
+      (list 1001))
+    (list
+      "fed boolean or"
+      "searchQuery \"delta OR barks\" fed"
+      (list 2001))
+    (list
+      "fed phrase within peer1"
+      "searchQuery \"\\\"alpha beta\\\"\" fed"
+      (list 1001))
+    (list
+      "fed phrase within peer2"
+      "searchQuery \"\\\"beta gamma\\\"\" fed"
+      (list 2002))
+    (list
+      "fed phrase peer2 alpha delta"
+      "searchQuery \"\\\"alpha delta\\\"\" fed"
+      (list 2001))
+    (list "fed empty peer list" "allDocs (fedIndex [])" (list))
+    (list
+      "fed single relabelled peer"
+      "rankTfIdf [\"alpha\"] (fedIndex [(5, p1)])"
+      (list 5001 5002))
+    (list
+      "acl peer1 only"
+      "aclFilter permitP1 (rankTfIdf [\"alpha\"] fed)"
+      (list 1001 1002))
+    (list
+      "acl allowlist preserves rank order"
+      "aclFilter permitList (rankTfIdf [\"alpha\"] fed)"
+      (list 1002 2001))
+    (list
+      "acl topN after filter"
+      "topNTfIdfAcl 1 permitP1 [\"alpha\"] fed"
+      (list 1001))
+    (list
+      "acl denies all"
+      "aclFilter permitNone (rankTfIdf [\"alpha\"] fed)"
+      (list))
+    (list
+      "acl on bm25"
+      "searchBm25Acl permitP1 1.5 0.75 [\"alpha\"] fed"
+      (list 1001 1002))
+    (list
+      "acl end-to-end tfidf"
+      "searchTfIdfAcl permitP1 [\"alpha\"] fed"
+      (list 1001 1002))))
+
+(define
+  fed-results
+  (search-batch fed-setup (map (fn (c) (nth c 1)) fed-cases)))
+
+(map-indexed
+  (fn
+    (i c)
+    (hk-test (nth c 0) (nth fed-results i) (nth c 2)))
+  fed-cases)
+
+{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}

lib/search/tests/parse.sx

@@ -0,0 +1,139 @@
+;; Phase 2 — query parser (parseQuery / searchQuery).
+;; AST cases assert showQ (parseQuery s); search cases assert searchQuery s idx
+;; against the standard corpus. Each group runs in one batched program eval.
+;;   doc 1 "the quick brown dog"   doc 2 "a quick brown fox"   doc 3 "the dog barks loudly"
+
+(define
+  parse-corpus
+  "idx = indexDoc 3 \"the dog barks loudly\" (indexDoc 2 \"a quick brown fox\" (indexDoc 1 \"the quick brown dog\" emptyIndex))\n")
+
+(define
+  ast-cases
+  (list
+    (list "single term" "showQ (parseQuery \"cat\")" "T:cat")
+    (list "term normalized" "showQ (parseQuery \"CAT\")" "T:cat")
+    (list "explicit and" "showQ (parseQuery \"cat AND dog\")" "(T:cat & T:dog)")
+    (list
+      "lowercase and keyword"
+      "showQ (parseQuery \"cat and dog\")"
+      "(T:cat & T:dog)")
+    (list "implicit and" "showQ (parseQuery \"cat dog\")" "(T:cat & T:dog)")
+    (list "or" "showQ (parseQuery \"cat OR dog\")" "(T:cat | T:dog)")
+    (list "not" "showQ (parseQuery \"NOT cat\")" "!T:cat")
+    (list
+      "and binds tighter than or"
+      "showQ (parseQuery \"cat AND dog OR bird\")"
+      "((T:cat & T:dog) | T:bird)")
+    (list
+      "or then and"
+      "showQ (parseQuery \"cat OR dog AND bird\")"
+      "(T:cat | (T:dog & T:bird))")
+    (list
+      "parens override precedence"
+      "showQ (parseQuery \"(cat OR dog) AND bird\")"
+      "((T:cat | T:dog) & T:bird)")
+    (list
+      "and with not"
+      "showQ (parseQuery \"cat AND NOT dog\")"
+      "(T:cat & !T:dog)")
+    (list
+      "two-word phrase"
+      "showQ (parseQuery \"\\\"quick brown\\\"\")"
+      "P:quick-brown")
+    (list
+      "three-word phrase"
+      "showQ (parseQuery \"\\\"quick brown fox\\\"\")"
+      "P:quick-brown-fox")
+    (list
+      "and left-assoc"
+      "showQ (parseQuery \"a AND b AND c\")"
+      "((T:a & T:b) & T:c)")
+    (list
+      "or left-assoc"
+      "showQ (parseQuery \"a OR b OR c\")"
+      "((T:a | T:b) | T:c)")
+    (list
+      "punctuation stripped"
+      "showQ (parseQuery \"cat, dog!\")"
+      "(T:cat & T:dog)")))
+
+(define
+  search-cases
+  (list
+    (list "term" "searchQuery \"quick\" idx" (list 1 2))
+    (list
+      "term normalized"
+      "searchQuery \"QUICK\" idx"
+      (list 1 2))
+    (list
+      "explicit and"
+      "searchQuery \"quick AND brown\" idx"
+      (list 1 2))
+    (list
+      "implicit and"
+      "searchQuery \"quick brown\" idx"
+      (list 1 2))
+    (list "and disjoint" "searchQuery \"the AND fox\" idx" (list))
+    (list "or" "searchQuery \"fox OR barks\" idx" (list 2 3))
+    (list "not" "searchQuery \"NOT the\" idx" (list 2))
+    (list "and not" "searchQuery \"quick AND NOT the\" idx" (list 2))
+    (list
+      "precedence and-or"
+      "searchQuery \"the AND dog OR fox\" idx"
+      (list 1 2 3))
+    (list
+      "precedence or-and"
+      "searchQuery \"fox OR the AND dog\" idx"
+      (list 1 2 3))
+    (list
+      "parens"
+      "searchQuery \"the AND (dog OR fox)\" idx"
+      (list 1 3))
+    (list
+      "phrase"
+      "searchQuery \"\\\"quick brown\\\"\" idx"
+      (list 1 2))
+    (list
+      "phrase one doc"
+      "searchQuery \"\\\"brown dog\\\"\" idx"
+      (list 1))
+    (list
+      "phrase and term"
+      "searchQuery \"\\\"quick brown\\\" AND dog\" idx"
+      (list 1))
+    (list
+      "not phrase"
+      "searchQuery \"NOT \\\"quick brown\\\"\" idx"
+      (list 3))
+    (list
+      "implicit and terms"
+      "searchQuery \"dog barks\" idx"
+      (list 3))))
+
+(define
+  ast-results
+  (search-batch "" (map (fn (c) (nth c 1)) ast-cases)))
+(define
+  search-results
+  (search-batch
+    parse-corpus
+    (map (fn (c) (nth c 1)) search-cases)))
+
+(map-indexed
+  (fn
+    (i c)
+    (hk-test
+      (str "ast: " (nth c 0))
+      (nth ast-results i)
+      (nth c 2)))
+  ast-cases)
+(map-indexed
+  (fn
+    (i c)
+    (hk-test
+      (str "search: " (nth c 0))
+      (nth search-results i)
+      (nth c 2)))
+  search-cases)
+
+{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}

lib/search/tests/prefix.sx

@@ -0,0 +1,63 @@
+;; Extension — prefix / wildcard queries.
+;; Corpus: 1 "alpha alpine"  2 "beta apple"  3 "banana alpha"
+;; allTerms sorted: alpha alpine apple banana beta
+
+(define
+  prefix-setup
+  "idx = indexDoc 3 \"banana alpha\" (indexDoc 2 \"beta apple\" (indexDoc 1 \"alpha alpine\" emptyIndex))\n")
+
+(define
+  prefix-cases
+  (list
+    (list
+      "prefix terms two matches"
+      "prefixTerms \"al\" idx"
+      (list "alpha" "alpine"))
+    (list
+      "prefix terms narrower"
+      "prefixTerms \"alp\" idx"
+      (list "alpha" "alpine"))
+    (list
+      "prefix terms wide"
+      "prefixTerms \"a\" idx"
+      (list "alpha" "alpine" "apple"))
+    (list "prefix terms single" "prefixTerms \"ban\" idx" (list "banana"))
+    (list "prefix terms exact term" "prefixTerms \"beta\" idx" (list "beta"))
+    (list "prefix terms none" "prefixTerms \"z\" idx" (list))
+    (list
+      "prefix docs union"
+      "prefixDocs \"al\" idx"
+      (list 1 3))
+    (list "prefix docs single term" "prefixDocs \"ban\" idx" (list 3))
+    (list
+      "prefix docs wide"
+      "prefixDocs \"a\" idx"
+      (list 1 2 3))
+    (list "prefix docs none" "prefixDocs \"z\" idx" (list))
+    (list
+      "prefix docs exact"
+      "prefixDocs \"alpha\" idx"
+      (list 1 3))
+    (list
+      "prefix rank ranks by matched terms"
+      "prefixRankTfIdf \"al\" idx"
+      (list 1 3))
+    (list
+      "prefix rank single doc"
+      "prefixRankTfIdf \"ban\" idx"
+      (list 3))
+    (list "prefix rank empty" "prefixRankTfIdf \"z\" idx" (list))))
+
+(define
+  prefix-results
+  (search-batch
+    prefix-setup
+    (map (fn (c) (nth c 1)) prefix-cases)))
+
+(map-indexed
+  (fn
+    (i c)
+    (hk-test (nth c 0) (nth prefix-results i) (nth c 2)))
+  prefix-cases)
+
+{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}

lib/search/tests/rank.sx

@@ -0,0 +1,90 @@
+;; Phase 3 — ranking (TF-IDF, BM25, top-N). Deterministic: ties broken by DocId.
+;; Corpora:
+;;   idx1: 1 "alpha alpha alpha gamma"  2 "alpha"  3 "beta"
+;;   idx2: 1 "cat"  2 "cat cat dog elephant frog grape"  3 "zzz"
+;;   idx3: 1 "kite"  2 "kite"   (identical docs -> tiebreak)
+
+(define
+  rank-setup
+  "idx1 = indexDoc 3 \"beta\" (indexDoc 2 \"alpha\" (indexDoc 1 \"alpha alpha alpha gamma\" emptyIndex))\nidx2 = indexDoc 3 \"zzz\" (indexDoc 2 \"cat cat dog elephant frog grape\" (indexDoc 1 \"cat\" emptyIndex))\nidx3 = indexDoc 2 \"kite\" (indexDoc 1 \"kite\" emptyIndex)\n")
+
+(define
+  rank-cases
+  (list
+    (list
+      "tfidf tf ordering"
+      "rankTfIdf [\"alpha\"] idx1"
+      (list 1 2))
+    (list
+      "tfidf rare term boosts"
+      "rankTfIdf [\"alpha\", \"beta\"] idx1"
+      (list 1 3 2))
+    (list
+      "tfidf single-doc term"
+      "rankTfIdf [\"gamma\"] idx1"
+      (list 1))
+    (list "tfidf absent term empty" "rankTfIdf [\"nope\"] idx1" (list))
+    (list "tfidf empty query empty" "rankTfIdf [] idx1" (list))
+    (list
+      "tfidf candidate union tie by docid"
+      "rankTfIdf [\"beta\", \"gamma\"] idx1"
+      (list 1 3))
+    (list
+      "tfidf tf ordering idx2"
+      "rankTfIdf [\"cat\"] idx2"
+      (list 2 1))
+    (list "topN tfidf 1" "topNTfIdf 1 [\"alpha\"] idx1" (list 1))
+    (list
+      "topN tfidf 2"
+      "topNTfIdf 2 [\"alpha\", \"beta\"] idx1"
+      (list 1 3))
+    (list
+      "topN exceeds results"
+      "topNTfIdf 10 [\"gamma\"] idx1"
+      (list 1))
+    (list "topN zero" "topNTfIdf 0 [\"alpha\"] idx1" (list))
+    (list
+      "bm25 tf+length flips tfidf"
+      "rankBm25 1.5 0.75 [\"cat\"] idx2"
+      (list 1 2))
+    (list
+      "bm25 b=0 ignores length"
+      "rankBm25 1.5 0.0 [\"cat\"] idx2"
+      (list 2 1))
+    (list
+      "bm25 alpha idx1"
+      "rankBm25 1.5 0.75 [\"alpha\"] idx1"
+      (list 1 2))
+    (list "bm25 absent empty" "rankBm25 1.5 0.75 [\"nope\"] idx1" (list))
+    (list
+      "bm25 single-doc term"
+      "rankBm25 1.5 0.75 [\"gamma\"] idx1"
+      (list 1))
+    (list "bm25 topN 1" "topNBm25 1 1.5 0.75 [\"cat\"] idx2" (list 1))
+    (list
+      "bm25 same candidate set"
+      "sort (rankBm25 1.5 0.75 [\"alpha\", \"beta\"] idx1)"
+      (list 1 2 3))
+    (list
+      "tfidf stable tiebreak"
+      "rankTfIdf [\"kite\"] idx3"
+      (list 1 2))
+    (list
+      "bm25 stable tiebreak"
+      "rankBm25 1.5 0.75 [\"kite\"] idx3"
+      (list 1 2))
+    (list "numDocs" "[numDocs idx1]" (list 3))
+    (list "docLen counts tokens" "[docLen 1 idx1]" (list 4))
+    (list "docFreq via index" "[docFreq \"alpha\" idx1]" (list 2))))
+
+(define
+  rank-results
+  (search-batch rank-setup (map (fn (c) (nth c 1)) rank-cases)))
+
+(map-indexed
+  (fn
+    (i c)
+    (hk-test (nth c 0) (nth rank-results i) (nth c 2)))
+  rank-cases)
+
+{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}

lib/search/tokenize.sx

@@ -0,0 +1,8 @@
+;; search tokenizer — Haskell source fragment.
+;; normalize (lowercase + strip punctuation), split on whitespace, attach positions.
+;; tokens :: String -> [String]
+;; positioned :: String -> [(String, Int)]  -- 0-based ordinal positions
+
+(define
+  search/tokenize-src
+  "lowerChar c = chr (toLower (ord c))\nnormChar c = if isAlphaNum c then lowerChar c else ' '\nisBlankCh c = c == ' '\ndropBlanks [] = []\ndropBlanks (c:cs) = if isBlankCh c then dropBlanks cs else c:cs\ntakeWord [] = []\ntakeWord (c:cs) = if isBlankCh c then [] else c : takeWord cs\nafterWord [] = []\nafterWord (c:cs) = if isBlankCh c then c:cs else afterWord cs\nsplitWords s = let s2 = dropBlanks s in if null s2 then [] else takeWord s2 : splitWords (afterWord s2)\nappendStr a b = a ++ b\njoinChars cs = foldr appendStr \"\" cs\ntokens s = map joinChars (splitWords (map normChar s))\nposFrom i [] = []\nposFrom i (x:xs) = (x, i) : posFrom (i + 1) xs\npositioned s = posFrom 0 (tokens s)\n")

plans/agent-briefings/search-loop.md

@@ -0,0 +1,110 @@
+# search-on-sx loop agent (single agent, queue-driven)
+
+Role: iterates `plans/search-on-sx.md` forever. **Full-text + structured search on
+Haskell** — tokenize, inverted index, query AST, boolean + phrase + ranked
+queries (TF-IDF / BM25), ACL-aware post-filter, federated index merge. Typed ADTs
+make query parsing clean; lazy lists make posting-list iteration efficient. Sits on
+`lib/haskell/` (1514/1514 already green); adds a search-shaped vocabulary on top.
+
+```
+description: search-on-sx queue loop
+subagent_type: general-purpose
+run_in_background: true
+isolation: worktree
+```
+
+## Prompt
+
+You are the sole background agent working `plans/search-on-sx.md`. Isolated
+worktree `/root/rose-ash-loops/search` on branch `loops/search`, forever, one
+commit per feature. Push to `origin/loops/search` after every commit. Never touch
+`main` or `architecture`.
+
+## Restart baseline — check before iterating
+
+1. Read `plans/search-on-sx.md` — roadmap + Progress log.
+2. `ls lib/search/` — pick up from the most advanced file.
+3. If `lib/search/tests/*.sx` exist, run them via `bash lib/search/conformance.sh`.
+   Green before new work.
+4. If `lib/search/scoreboard.md` exists, that's your baseline.
+5. Read the `lib/haskell/` public API once — that's your substrate. `lib/haskell/
+   haskell.sx` exists; also study `runtime.sx`, `eval.sx`, `parser.sx`, `infer.sx`,
+   `match.sx`, `map.sx`, `set.sx`, `testlib.sx`. Learn how to declare ADTs, pattern
+   match, and use the `Map`/`Set` helpers before writing index code. Verify the real
+   exported names with sx_find_all / grep — don't assume from the plan's sketch.
+
+## The queue
+
+Phase order per `plans/search-on-sx.md`:
+
+- **Phase 1** — tokenize + inverted index + simple term lookup
+  (`Map Term [(DocId,[Pos])]`, insert/lookup, `(search/index doc)`,
+  `(search/query term)`).
+- **Phase 2** — query AST + boolean/phrase eval (Term | And | Or | Not | Phrase;
+  posting-list set ops; positional phrase match).
+- **Phase 3** — ranking (TF-IDF, BM25), top-N.
+- **Phase 4** — ACL-aware post-filter + federation (merge per-peer indices).
+
+Within a phase, pick the checkbox that unlocks the most tests per effort.
+
+Every iteration: implement → test → commit → tick `[ ]` → Progress log → next.
+
+## Ground rules (hard)
+
+- **Scope:** only `lib/search/**` and `plans/search-on-sx.md`. Do **not** edit
+  `spec/`, `hosts/`, `shared/`, other `lib/<lang>/` dirs, `lib/stdlib.sx`, or
+  `lib/` root. May **import** from `lib/haskell/` only (its public API). Do **not**
+  modify Haskell.
+- **NEVER call `sx_build`.** 600s watchdog. If the sx_server binary is broken →
+  Blockers entry, stop. Run tests by invoking the sx_server binary directly from a
+  conformance.sh (model it on `lib/haskell/conformance.sh`), pointing `SX_SERVER`
+  at `/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe` — fresh
+  worktrees have no `_build/`, so the relative path won't resolve.
+- **Shared-file issues** → plan's Blockers with minimal repro; don't fix here.
+- **SX files:** `sx-tree` MCP tools ONLY. **They take `file:` not `path:`** — a
+  wrong key yields `Yojson Type_error("Expected string, got null")`, which looks
+  like a broken binary but is just a param mismatch. `sx_validate` after edits.
+  Path-based edits (`sx_replace_node`) count comment headers in their indices and
+  can clobber the wrong node — re-read after, or prefer `sx_write_file` for small
+  files.
+- **Unicode in `.sx`:** raw UTF-8 only, never `\uXXXX` escapes.
+- **Commit granularity:** one feature per commit. Short factual messages
+  (`search: phrase query positional match + 7 tests`). Push to `origin/loops/search`.
+- **Plan file:** update Progress log (newest first) + tick boxes every commit.
+
+## search-specific gotchas
+
+- **Posting lists are the hot path.** Keep them sorted by DocId so boolean AND/OR
+  are linear merges, not nested scans. Phrase match needs positions, so store
+  `(DocId, [Pos])` — don't drop positions early to save space; you can't recover them.
+- **Tokenization decides recall.** Normalize consistently (lowercase, strip
+  punctuation) on BOTH index and query side, or queries silently miss. Test the
+  index/query symmetry explicitly.
+- **Ranking must be deterministic on ties.** TF-IDF/BM25 scores collide; always
+  add a stable tiebreak (DocId ascending) or tests flake.
+- **ACL filter is per-viewer and post-ranking.** Filter the result list against the
+  viewer, after scoring — never bake visibility into the index (the same index
+  serves all viewers). Inject the permit predicate; don't hardwire an ACL module
+  that doesn't exist yet.
+- **Federation merges indices, not results.** Merging per-peer inverted indices
+  (union posting lists per term) is cleaner and rank-correct vs merging ranked
+  result lists. Mock peer indices in tests.
+
+## General gotchas (all loops)
+
+- SX `do` = R7RS iteration. Use `begin` for multi-expr sequences.
+- `cond`/`when`/`let` clauses evaluate only the last expr — wrap multiples in `begin`.
+- `let` is parallel, not sequential — nest `let`s when a binding references an earlier one.
+- `env-bind!` creates a binding; `env-set!` mutates an existing one (walks scope chain).
+- `sx_validate` after every structural edit.
+- Namespace-prefix all guest helpers (`search/...`) — short/host-colliding names
+  get silently shadowed or hang the runtime.
+
+## Style
+
+- No comments in `.sx` unless non-obvious.
+- No new planning docs — update `plans/search-on-sx.md` inline.
+- Short, factual commit messages.
+- One feature per iteration. Commit. Log. Push. Next.
+
+Go. Start by reading the plan; find the first unchecked `[ ]`; implement it.

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` → **0/0** (not yet started)
+`bash lib/feed/conformance.sh` → **189/189** (Phases 1–4 + TF-IDF, notifications, home, smart-dedupe, trending, mute, pagination, threading)
 
 ## Ground rules
 
@@ -59,47 +59,118 @@ lib/feed/api.sx           lib/feed/fed.sx
 
 ## Phase 1 — Stream model + basic ops
 
-- [ ] `lib/feed/normalize.sx` — activity record schema; coerce arbitrary inputs
-- [ ] `lib/feed/stream.sx` — APL vector representation; filter by predicate; sort by
+- [x] `lib/feed/normalize.sx` — activity record schema; coerce arbitrary inputs
+- [x] `lib/feed/stream.sx` — APL vector representation; filter by predicate; sort by
   `:at`; take N (`↑`); reverse (`⌽`)
-- [ ] `lib/feed/api.sx` — `(feed/post activity)`, `(feed/all)`
-- [ ] `lib/feed/tests/basic.sx` — 15+ cases: post, query, filter, sort
-- [ ] `lib/feed/scoreboard.{json,md}`
-- [ ] `lib/feed/conformance.sh`
+- [x] `lib/feed/api.sx` — `(feed/post activity)`, `(feed/all)`
+- [x] `lib/feed/tests/basic.sx` — 30 cases: normalize defaults, filter, sort, take, api
+- [x] `lib/feed/scoreboard.{json,md}`
+- [x] `lib/feed/conformance.sh`
 
 ## Phase 2 — Fanout via outer product
 
-- [ ] follower graph: `followers user → vector of user ids`
-- [ ] fanout: activities `∘.×` followers → matrix `(activity, follower)` pairs
-- [ ] flatten to inbox events vector
-- [ ] dedupe — group by `(actor, verb, object)` collapse to one inbox event per
-  receiver
-- [ ] `lib/feed/tests/fanout.sx` — 20+ cases: small graph, mutual follow, popular
-  actor (high-fanout), cross-post dedupe
+- [x] follower graph: `followers user → vector of user ids` (`feed/follow-graph`,
+  `feed/followers`; graph = `{followee -> (followers)}` dict)
+- [x] fanout: activities `∘.×` audience → matrix via `apl-outer feed/-mk-event`
+- [x] flatten to inbox events vector (`feed/-flatten` rank-2 → rank-1)
+- [x] dedupe — `feed/dedupe-inbox` by `(to, actor, verb, object)`; also
+  `feed/dedupe-activities` `(actor verb object)` and `feed/dedupe-collapse`
+  `(verb object)` for cross-actor likes
+- [x] `lib/feed/tests/fanout.sx` — 29 cases: small graph, mutual follow, star
+  (high-fanout), empty graph, unfollowed actor, cross-post dedupe
 
 ## Phase 3 — Aggregation + ranking
 
-- [ ] group-by — `(actor, day) → count` via key-reduce
-- [ ] velocity score — recent activity count over window
-- [ ] recency score — decay by age
-- [ ] composite rank — weighted sum of components
-- [ ] top-N per timeline
-- [ ] `lib/feed/tests/rank.sx` — 20+ cases: ranking stable on tie, decay shape,
-  per-user weighting
+- [x] group-by — `feed/group-by`/`feed/group-count` key-reduce; `feed/by-actor-day`
+  buckets `(actor, day)` via `feed/day` (string-joined keys)
+- [x] velocity score — `feed/velocity` counts actor's activities in `(at-window, at]`
+- [x] recency score — `feed/recency` half-life decay `0.5^(age/hl)`
+- [x] composite rank — `feed/composite` weighted sum of `(weight scorer)` parts
+- [x] top-N per timeline — `feed/top` = rank then take
+- [x] `lib/feed/tests/rank.sx` — 24 cases: decay shape, velocity burst, stable
+  tie-break, top-N, composite
 
 ## Phase 4 — Visibility filter + federation
 
-- [ ] ACL filter — each candidate activity passed through `(acl/permit? viewer :read
-  activity)`
-- [ ] fed-sx outbound — local `feed/post` fans out to remote followers' inboxes
-- [ ] fed-sx inbound — peer activities arrive at local inbox
-- [ ] backfill on subscribe — request peer history, merge into local stream
-- [ ] `lib/feed/tests/integration.sx` — federated timeline with ACL applied
+`lib/acl/` and fed-sx don't exist yet and are out of scope (import `lib/apl/`
+only), so ACL/transport are injected: `permit?`, `remote?`, `send-fn`, `fetch-fn`
+are function parameters. Real acl-sx / fed-sx wire in at the call site unchanged.
+
+- [x] ACL filter — `feed/visible stream viewer permit?`; default `feed/permit-acl?`
+  reads `:visible-to` allowlist (+ author-sees-own); per-viewer, never cached
+- [x] fed-sx outbound — `feed/federate`/`feed/deliver` fan out then partition
+  local vs remote inboxes; remote events handed to injected `send-fn`
+- [x] fed-sx inbound — `feed/inbound` normalizes + `feed/ingest` dedupes peer
+  activities into the local stream
+- [x] backfill on subscribe — `feed/backfill local fetch-fn peer-id`
+- [x] `lib/feed/tests/integration.sx` — 22 cases incl. end-to-end
+  `feed/timeline` (federated → ACL for viewer → recency rank → top-N)
 
 ## Progress log
 
-(loop fills this in)
+- **Phase 1 done (30/30).** Stream = APL rank-1 array whose ravel holds activity
+  dicts. `normalize.sx` (record schema + accessors), `stream.sx` (filter via `/`
+  compress, sort via `⍋` grade-up [stable], take via `↑`, reverse via `⌽`,
+  by-actor/verb/object/since predicates), `api.sx` (mutable log: post/all/reset!/size).
+  Substrate: `apl-compress`, `apl-grade-up`, `apl-take`, `apl-reverse`, `make-array`.
+  Grade-up returns 1-based indices (⎕IO=1), is stable on ties → deterministic sort.
+- **Phase 2 done (59/59 total).** `fanout.sx` (graph + `apl-outer` showcase),
+  `dedupe.sx` (per-key dedupe, first-wins stable). Key APL gotcha: `scalar?` is
+  true for ANY dict and `disclose` nils a non-array dict, so an apl-outer combiner
+  MUST `enclose` its event dict — apl-outer discloses it back intact. `apl-unique`
+  preserves first-occurrence order; dict `keys` order is NOT stable, so
+  `feed/audience` sorts (else recipient ordering flakes). `apl-compress` needs a
+  rank-1 array, so the (activity×follower) matrix is flattened to its ravel before
+  the edge-guard filter.
+- **Phase 3 done (83/83 total).** `aggregate.sx` (group-by/count, day buckets) +
+  `rank.sx` (recency/velocity/engagement scorers, composite, top-N). `sort` is
+  single-arg ascending only — no comparator — so ranking uses a stable two-pass
+  `apl-grade-down` (by :at desc, then by score desc) for deterministic tie-breaks.
+  Dict keys must be strings, so composite group keys are string-joined ("actor#day").
+- **Phase 4 done (105/105 total).** `acl.sx` (per-viewer `feed/visible`,
+  `feed/timeline` capstone) + `fed.sx` (merge/ingest/inbound/backfill/federate/
+  deliver). ACL/transport are dependency-injected (permit?/remote?/send-fn/fetch-fn)
+  since lib/acl + fed-sx don't exist. `feed/normalize` now MERGEs defaults over the
+  raw dict (was projecting to 5 keys) so extra metadata (:visible-to, peer fields)
+  survives — matches the "flexible bag" principle.
 
-## Blockers
+## Roadmap is complete (all 4 phases). Possible follow-ups:
 
-(loop fills this in)
+- Wire real acl-sx once `lib/acl/` exists (swap injected `permit?`).
+- Wire real fed-sx transport (swap `send-fn`/`fetch-fn`).
+- [x] TF-IDF over `:tags` for content ranking — `content.sx`: `feed/tag-df`,
+  `feed/tag-idf` (log N/df), `feed/tfidf-score`, `feed/by-relevance`; 15 tests.
+  Composes as a scorer with rank.sx. (120/120 total.)
+- [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.)
+- [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.)
+- [x] Trending — `feed/trending` / `feed/trending-actors`: objects/actors ranked
+  by activity count in a recency window, count-desc with key-asc tiebreak
+  (`trending.sx`); 11 tests. (154/154 total.)
+- [x] Mute/block — `feed/mute-actors` / `feed/mute-tags` / `feed/mute-objects` /
+  `feed/apply-prefs`: viewer-controlled per-request filtering (complements ACL's
+  author-controlled visibility) (`mute.sx`); 9 tests. (163/163 total.)
+- [x] Pagination — `feed/page`/`feed/page-count` (offset) + `feed/before`/
+  `feed/after`/`feed/page-before`/`feed/next-cursor` (cursor by :at, stable under
+  inserts) (`page.sx`); 14 tests. (177/177 total.)
+- [x] Threading — `feed/replies`/`feed/reply-count`/`feed/thread`/
+  `feed/thread-objects`/`feed/thread-size`: conversation closure over `:reply-to`
+  (transitive fixpoint), chronological (`thread.sx`); 12 tests. (189/189 total.)
+
+(none)
+
+## Notes for next iteration
+
+- sx-tree MCP tools take `file:` NOT `path:` (CLAUDE.md is stale). Wrong key →
+  `Yojson Type_error("Expected string, got null")`. Looks like a broken binary, isn't.
+- sx_server binary lives in main repo: `/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe`
+  (worktree has no `_build`). conformance.sh already points there with relative fallback.
+- Phase 2 substrate verified available: `apl-outer` (∘.×), `apl-member` (∊),
+  `apl-unique`, `apl-iota` (1-based).

plans/search-on-sx.md

@@ -10,7 +10,7 @@ extension that merges per-peer indices.
 
 ## Status (rolling)
 
-`bash lib/search/conformance.sh` → **0/0** (not yet started)
+`bash lib/search/conformance.sh` → **122/122** (Phases 1–4 complete)
 
 ## Ground rules
 
@@ -61,46 +61,110 @@ lib/search/index.sx                     lib/search/eval.sx
 
 ## Phase 1 — Tokenize + index
 
-- [ ] `lib/search/tokenize.sx` — normalize (lowercase, strip punctuation), split on
+- [x] `lib/search/tokenize.sx` — normalize (lowercase, strip punctuation), split on
   whitespace, return positions
-- [ ] `lib/search/index.sx` — inverted index data structure (typed `Map` from
-  haskell lib); `insert`, `delete`, `lookup`
-- [ ] `lib/search/api.sx` — `(search/index doc)`, `(search/lookup term)`
-- [ ] `lib/search/tests/index.sx` — 15+ cases: tokenize, insert + lookup, update,
-  delete, multi-doc
-- [ ] `lib/search/scoreboard.{json,md}`
-- [ ] `lib/search/conformance.sh`
+- [x] `lib/search/index.sx` — inverted index data structure; `indexDoc`, `deleteDoc`,
+  `lookupTerm`, `docFreq`, `allTerms`. (Data.Map's public API lacks
+  toList/keys/map/filter, so a sorted assoc-list `[(Term,[(DocId,[Pos])])]` is used —
+  the conceptual `Map Term [(DocId,[Pos])]` with free term iteration.)
+- [x] `lib/search/api.sx` — assembles `search/src` (tokenize + index); Haskell entry
+  points `indexDoc` / `lookupTerm`
+- [x] `lib/search/tests/index.sx` — 18 cases: tokenize, insert + lookup, update,
+  delete, multi-doc, positions, docFreq, allTerms
+- [x] `lib/search/scoreboard.{json,md}`
+- [x] `lib/search/conformance.sh`
 
 ## Phase 2 — Query AST + boolean evaluation
 
-- [ ] Query ADT: `Term Text | And Query Query | Or Query Query | Not Query |
-  Phrase [Text]`
-- [ ] `lib/search/parse.sx` — query syntax parser (boolean operators, quoted phrases)
-- [ ] `lib/search/eval.sx` — boolean eval via set ops on posting lists
-- [ ] phrase eval — adjacency check using positions
-- [ ] `lib/search/tests/boolean.sx` — 25+ cases: term, and, or, not, phrase,
-  composition, parser edge cases
+- [x] Query ADT: `Term String | And Query Query | Or Query Query | Not Query |
+  Phrase [String]` (in `lib/search/query.sx`)
+- [x] `lib/search/parse.sx` — query syntax parser: tokenizer + recursive-descent
+  (OR < AND < NOT precedence, implicit AND on adjacency, quoted phrases, parens,
+  case-insensitive keywords); `parseQuery`, `searchQuery`, `showQ`
+- [x] `lib/search/query.sx` — boolean eval via set ops on docid-sorted posting lists
+  (sortedUnion/Inter/Diff, Not over allDocs universe)
+- [x] phrase eval — positional adjacency check (phraseInDoc / phraseStartsAt)
+- [x] `lib/search/tests/boolean.sx` — 28 cases: term, and, or, not, phrase,
+  composition (parser edge cases move to the parse.sx suite)
 
 ## Phase 3 — Ranking
 
-- [ ] document frequency tracking — extend index with `df` per term
-- [ ] TF-IDF scoring
-- [ ] BM25 scoring (configurable k1, b)
-- [ ] top-N retrieval (heap-based)
-- [ ] `lib/search/tests/rank.sx` — 20+ cases: TF-IDF behavior, BM25 vs TF-IDF,
-  ranking stability, top-N correctness
+- [x] document frequency — `docFreq`/`idf`/`bm25idf` derived from the index
+  (posting-list length); no separate df store needed
+- [x] TF-IDF scoring (`rankTfIdf`)
+- [x] BM25 scoring, configurable k1/b (`rankBm25 k1 b`)
+- [x] top-N retrieval (`topNTfIdf`/`topNBm25` — sortBy + take; stable DocId tiebreak)
+- [x] `lib/search/tests/rank.sx` — 23 cases: TF-IDF tf/idf behavior, BM25 length-norm
+  + tf-saturation flips vs TF-IDF, b-parameter effect, tiebreak stability, top-N
 
 ## Phase 4 — ACL filter + federation
 
-- [ ] post-filter — each candidate result tested via `(acl/permit? viewer :read doc)`
-- [ ] federated query — fan out to peer instances via fed-sx, merge results
-- [ ] merge policy — interleave by rank, dedupe by `(peer, doc-id)`
-- [ ] `lib/search/tests/integration.sx` — federated search with ACL filter
+- [x] post-filter — `aclFilter`/`searchTfIdfAcl`/`topNTfIdfAcl`/`searchBm25Acl` take an
+  injected `permit :: DocId -> Bool` predicate, applied post-rank (never in the index)
+- [x] federated query — `fedIndex :: [(PeerId, Index)] -> Index` merges per-peer
+  inverted indices (union posting lists per term); rank/search run once over the merge
+- [x] merge policy — relabel local DocIds to global `gid = peer*1000 + local`
+  (bijection ⇒ dedupe by (peer,doc-id) is automatic); ranking interleaves peers by score
+- [x] `lib/search/tests/integration.sx` — 21 cases: index merge, cross-peer df/lookup,
+  position preservation, boolean/phrase over the merge, ACL filter + top-N + bm25
+
+## Extensions (post-roadmap, search-shaped vocabulary)
+
+- [x] prefix / wildcard queries (`prefixTerms`, `prefixDocs`, `prefixRankTfIdf`) — 14 tests
+- [ ] fuzzy matching — edit distance term expansion
+- [ ] result pagination (offset / limit)
+- [ ] snippet / highlight generation
+- [ ] stemming (suffix stripping) — recall-improving normalizer
 
 ## Progress log
 
-(loop fills this in)
+- **Extension: prefix/wildcard queries (136/136 total).** `prefixTerms` matches every
+  indexed term starting with a prefix (via allTerms + isPrefixOf); `prefixDocs` unions
+  their docs; `prefixRankTfIdf` ranks treating the matched terms as the query. 14 tests.
+- **Phase 4 complete — federation + ACL (122/122 total). Roadmap done.** `fedIndex`
+  merges per-peer inverted indices (union posting lists per term) after relabelling
+  local DocIds to global `gid = peer*1000 + local` — the bijection makes (peer,doc-id)
+  dedupe automatic and keeps positions, so ranking runs once over the merge and
+  interleaves peers by score (rank-correct). ACL is a post-rank `filter` over an
+  injected `permit :: DocId -> Bool` (viewer baked in by the caller) — never in the
+  index; `searchTfIdfAcl`/`topNTfIdfAcl`/`searchBm25Acl`. 21 integration tests.
+- **Phase 3 complete — ranking (101/101 total).** TF-IDF (`rankTfIdf`) and BM25
+  (`rankBm25 k1 b`) over the candidate set (docs containing any query term), scores
+  as floats with deterministic DocId-ascending tiebreak; `topNTfIdf`/`topNBm25` via
+  sortBy+take. df/idf derived from posting-list length (no separate df store). 23
+  tests incl. a BM25-vs-TF-IDF flip (length-norm + tf-saturation) and the b-parameter
+  effect. Float division/`log`/float literals all work in haskell-on-sx.
+- **Phase 2 complete — parser (78/78 total).** Query tokenizer (ord-based
+  delimiters, quoted phrases) + recursive-descent parser with OR<AND<NOT precedence,
+  implicit AND on adjacency, parens, case-insensitive keywords. `parseQuery`,
+  `searchQuery`, `showQ` (canonical render for AST tests). 32 tests in parse.sx.
+  **haskell-on-sx parser gotchas hit while writing this (see parse.sx header):**
+  (1) escaped char literals like `'\"'` break the tokenizer — match delimiters by
+  `ord c == 34`; (2) an `[]` *pattern* inside a `case` alt breaks the parser — use
+  multi-clause functions instead; (3) `case`/constructor patterns and `let (a,b)=..`
+  are fine. Embedded Haskell string literals in a `.sx` source string need single
+  `\"`, not `\\\"`.
+- **Phase 2 boolean/phrase eval (46/46 total).** Query ADT
+  `Term|And|Or|Not|Phrase` + `evalQuery :: Index -> Query -> [DocId]` in query.sx.
+  Boolean ops are linear merges over docid-sorted posting lists; Not subtracts from
+  the allDocs universe; Phrase checks positional adjacency. 28 tests in boolean.sx.
+  Refactored both suites to **batch all cases into one program eval** (search-batch
+  in testlib) — under the heavy CPU load on this box (~11 on 2 cores), 18–28 separate
+  hk-eval-program calls timed out; one combined eval per suite is ~20× faster.
+  Parser (parse.sx) is the remaining Phase 2 box.
+- **Phase 1 complete (18/18).** Tokenizer (lowercase + strip punctuation + positions),
+  inverted index as sorted assoc-list `[(Term,[(DocId,[Pos])])]`, indexDoc/deleteDoc/
+  lookupTerm/docFreq/allTerms. Search lib is Haskell source assembled into `search/src`
+  and evaluated via the haskell-on-sx interpreter; tests reuse `hk-test` counters and a
+  `search-eval` helper that forces HK values to plain SX. conformance.sh models
+  lib/haskell (MODE=counters, COUNTERS_PASS/FAIL=hk-test-pass/fail).
 
 ## Blockers
 
-(loop fills this in)
+- **None.** Note: the box is heavily CPU-oversubscribed by sibling loop agents
+  (load ~11 on 2 cores); each program eval is ~10× slower than nominal, so suite
+  timeout is set to 600s. Runs are correct, just slow.
+- **Data.Map public API gap (informational, not fixing):** the haskell-on-sx
+  `import Data.Map` binds only empty/singleton/insert/lookup/member/size/null/delete/
+  insertWith/adjust/findWithDefault — no toList/keys/elems/map/filter/unionWith. Index
+  uses a pure assoc-list instead so term iteration and federation merge stay simple.