events: reschedule notifications + 7 tests

ev/reschedule-notifications: when an event carries per-occurrence overrides,
reads the roster at each overridden occurrence's original occ-key and emits a
reschedule message per booked attendee (old-start/new-start/new-duration).
Idempotency key = original-key/reschedule/new-start. 272/272 green.

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

.claude/scheduled_tasks.lock

@@ -1 +1 @@
-{"sessionId":"bf20a443-9df8-4cb9-932e-8c6f4c4625c2","pid":1303602,"procStart":"253831081","acquiredAt":1779865895644}
+{"sessionId":"c4d97db1-361c-4a04-a99b-c838f9385469","pid":2426590,"procStart":"349789073","acquiredAt":1780789990975}

lib/events/api.sx

@@ -0,0 +1,251 @@
+;; lib/events/api.sx — public events surface over calendar + availability.
+;;
+;; A `store` is an immutable value holding scheduled events and (in-memory)
+;; bookings:
+;;
+;;   {:events (event ...) :bookings ((actor key) ...)}
+;;
+;; The in-memory `:bookings` list supports pure, value-level queries. The
+;; DURABLE booking path (ev/*-occ! and ev/*-p) keeps bookings in persist
+;; streams via booking.sx — capacity-safe, cancellable, replayable — and
+;; derives availability from those streams. Use the persist path for real
+;; bookings; the in-memory path for projections and tests.
+;;
+;; All queries are windowed: agenda/free/next-free expand recurring events into
+;; concrete occurrences within an explicit (or derived) window before running
+;; the Datalog availability rules.
+
+(define ev/store (fn (events bookings) {:bookings bookings :events events}))
+
+(define ev/empty (fn () (ev/store (list) (list))))
+
+(define ev/events (fn (store) (get store :events)))
+(define ev/bookings (fn (store) (get store :bookings)))
+
+;; Add a (constructed) event to the store.
+(define
+  ev/add-event
+  (fn
+    (store event)
+    (ev/store (cons event (ev/events store)) (ev/bookings store))))
+
+;; Schedule a fresh event from parts, returning the updated store. rrule may be
+;; nil for a one-off. (Booking is separate — see ev/book.)
+(define
+  ev/schedule
+  (fn
+    (store id dtstart duration rrule capacity)
+    (ev/add-event store (ev-event id dtstart duration rrule capacity))))
+
+;; Record that `actor` holds the occurrence with `key` (in-memory only — see
+;; ev/book-occ! for the durable, capacity-safe path).
+(define
+  ev/book
+  (fn
+    (store actor key)
+    (ev/store
+      (ev/events store)
+      (cons (list actor key) (ev/bookings store)))))
+
+;; The event with `id`, or nil.
+(define
+  ev/event-by-id
+  (fn
+    (store id)
+    (reduce
+      (fn
+        (found ev)
+        (if (nil? found) (if (= (get ev :id) id) ev found) found))
+      nil
+      (ev/events store))))
+
+;; Capacity of the event an occurrence belongs to (0 if unknown).
+(define
+  ev/capacity-of
+  (fn
+    (store occ)
+    (let
+      ((ev (ev/event-by-id store (get occ :id))))
+      (if (nil? ev) 0 (get ev :capacity)))))
+
+;; The maximum event duration in the store (0 when empty) — used to widen
+;; expansion windows so any occurrence overlapping a query is captured.
+(define
+  ev/store-max-duration
+  (fn
+    (store)
+    (reduce
+      (fn (m ev) (max m (get ev :duration)))
+      0
+      (ev/events store))))
+
+;; All occurrences across all events within [ws, we), ascending by start.
+(define
+  ev/agenda
+  (fn (store ws we) (ev-expand-all (ev/events store) ws we)))
+
+(define
+  ev-key-member?
+  (fn
+    (k keys)
+    (cond
+      ((empty? keys) false)
+      ((= k (first keys)) true)
+      (else (ev-key-member? k (rest keys))))))
+
+;; Occurrence keys `actor` has booked (in-memory store).
+(define
+  ev/actor-keys
+  (fn
+    (store actor)
+    (reduce
+      (fn
+        (acc b)
+        (if (= (first b) actor) (cons (first (rest b)) acc) acc))
+      (list)
+      (ev/bookings store))))
+
+;; The agenda restricted to occurrences `actor` is booked into (in-memory).
+(define
+  ev/agenda-for
+  (fn
+    (store actor ws we)
+    (let
+      ((keys (ev/actor-keys store actor)))
+      (filter
+        (fn (o) (ev-key-member? (ev-occ-key o) keys))
+        (ev/agenda store ws we)))))
+
+;; Build an availability db over occurrences expanded in [ws, we) using the
+;; in-memory bookings.
+(define
+  ev/avail-window-db
+  (fn
+    (store ws we)
+    (ev-avail-db (ev/agenda store ws we) (ev/bookings store))))
+
+;; Is `actor` free across [qs, qe)? Expands a window wide enough (back by the
+;; longest event) to capture any occurrence that could overlap.
+(define
+  ev/free?
+  (fn
+    (store actor qs qe)
+    (ev-free?
+      (ev/avail-window-db store (- qs (ev/store-max-duration store)) qe)
+      actor
+      qs
+      qe)))
+
+;; Earliest free slot of `duration` for `actor` in [after, horizon), or nil.
+(define
+  ev/next-free
+  (fn
+    (store actor after duration horizon)
+    (ev-next-free
+      (ev/avail-window-db
+        store
+        (- after (ev/store-max-duration store))
+        horizon)
+      actor
+      after
+      duration
+      horizon)))
+
+;; Overlapping double-bookings for `actor` among occurrences in [ws, we).
+(define
+  ev/conflicts
+  (fn
+    (store actor ws we)
+    (ev-conflicts (ev/avail-window-db store ws we) actor)))
+
+(define
+  ev/has-conflict?
+  (fn
+    (store actor ws we)
+    (> (len (ev/conflicts store actor ws we)) 0)))
+
+;; ---- durable, persist-backed booking path ----
+;; These take a persist backend `b` (persist/open) plus the schedule `store`.
+;; Bookings live in per-occurrence streams (booking.sx); availability is derived
+;; by replaying those streams for the occurrences in the query window.
+
+;; Durably book `actor` into occurrence `occ` (dict {:id :start :end}),
+;; capacity-safe. Returns the booking.sx result (:booked / :full / :already).
+(define
+  ev/book-occ!
+  (fn
+    (b store actor occ)
+    (ev/book! b (ev-occ-key occ) (ev/capacity-of store occ) actor)))
+
+;; Durably cancel `actor`'s seat on `occ`, freeing capacity.
+(define
+  ev/cancel-occ!
+  (fn (b store actor occ) (ev/cancel! b (ev-occ-key occ) actor)))
+
+;; Live roster / seats-left for a specific occurrence from persist.
+(define ev/roster-occ (fn (b occ) (ev/roster b (ev-occ-key occ))))
+
+(define
+  ev/seats-left-occ
+  (fn
+    (b store occ)
+    (ev/seats-left b (ev-occ-key occ) (ev/capacity-of store occ))))
+
+;; Derive (actor key) booking pairs from the persist rosters of `occs`.
+(define
+  ev/persist-bookings
+  (fn
+    (b occs)
+    (reduce
+      (fn
+        (acc occ)
+        (let
+          ((key (ev-occ-key occ)))
+          (append
+            acc
+            (map (fn (actor) (list actor key)) (ev/roster b key)))))
+      (list)
+      occs)))
+
+;; Availability db over [ws, we) with bookings sourced from persist streams.
+(define
+  ev/avail-db-p
+  (fn
+    (b store ws we)
+    (let
+      ((occs (ev/agenda store ws we)))
+      (ev-avail-db occs (ev/persist-bookings b occs)))))
+
+;; Persist-backed availability queries (mirror the in-memory ev/free? etc).
+(define
+  ev/free-p?
+  (fn
+    (b store actor qs qe)
+    (ev-free?
+      (ev/avail-db-p b store (- qs (ev/store-max-duration store)) qe)
+      actor
+      qs
+      qe)))
+
+(define
+  ev/next-free-p
+  (fn
+    (b store actor after duration horizon)
+    (ev-next-free
+      (ev/avail-db-p b store (- after (ev/store-max-duration store)) horizon)
+      actor
+      after
+      duration
+      horizon)))
+
+(define
+  ev/conflicts-p
+  (fn
+    (b store actor ws we)
+    (ev-conflicts (ev/avail-db-p b store ws we) actor)))
+
+(define
+  ev/has-conflict-p?
+  (fn
+    (b store actor ws we)
+    (> (len (ev/conflicts-p b store actor ws we)) 0)))

lib/events/availability.sx

@@ -0,0 +1,177 @@
+;; lib/events/availability.sx — free/busy + conflict detection on Datalog.
+;;
+;; Availability is per-actor and is forward-chained Datalog over two EDB
+;; relations:
+;;
+;;   (occurrence Key EventId Start End)   ; an expanded calendar occurrence
+;;   (booking    Actor Key)               ; actor attends/holds that occurrence
+;;
+;; The derived relations are the whole policy:
+;;
+;;   busy(A,S,E)        — A is committed for [S,E) (a booked occurrence)
+;;   conflict(A,O1,O2)  — A double-booked into two overlapping occurrences
+;;   busy_in(A,QS,QE)   — A is busy somewhere inside query window [QS,QE)
+;;
+;; Intervals are half-open [Start,End) in epoch minutes (see calendar.sx), so
+;; adjacent slots (E == next start) do NOT conflict. Conflict pairs are
+;; canonical (O1 < O2 by key) so each overlap is reported once. The same `busy`
+;; rule answers "is A free in [QS,QE)?" (busy_in is empty) and feeds "when is A
+;; next free?" (ev-next-free probes candidate slots with the same rule).
+
+;; A stable key for an occurrence dict {:id :start :end}.
+(define ev-occ-key (fn (occ) (str (get occ :id) "@" (get occ :start))))
+
+(define
+  ev-occurrence-fact
+  (fn
+    (occ)
+    (list
+      (quote occurrence)
+      (ev-occ-key occ)
+      (get occ :id)
+      (get occ :start)
+      (get occ :end))))
+
+(define ev-occurrence-facts (fn (occs) (map ev-occurrence-fact occs)))
+
+(define ev-booking-fact (fn (actor key) (list (quote booking) actor key)))
+
+(define ev-qwindow-fact (fn (qs qe) (list (quote qwindow) qs qe)))
+
+;; Range restriction: each comparison's variables are bound by an earlier
+;; positive literal (qwindow / busy precede the < tests). Conflict uses
+;; (< O1 O2) on the keys so each overlapping pair is reported once.
+(define
+  ev-avail-rules
+  (quote
+    ((busy A S E <- (booking A O) (occurrence O _ S E))
+      (conflict
+        A
+        O1
+        O2
+        <-
+        (booking A O1)
+        (booking A O2)
+        (occurrence O1 _ S1 E1)
+        (occurrence O2 _ S2 E2)
+        (< O1 O2)
+        (< S1 E2)
+        (< S2 E1))
+      (busy_in A QS QE <- (qwindow QS QE) (busy A S E) (< S QE) (< QS E)))))
+
+;; Build a Datalog db from EDB facts under the availability ruleset.
+(define ev-build-avail (fn (facts) (dl-program-data facts ev-avail-rules)))
+
+;; Convenience: build a db from occurrence dicts + booking pairs.
+;; bookings is a list of (actor key) pairs.
+(define
+  ev-avail-db
+  (fn
+    (occs bookings)
+    (ev-build-avail
+      (append
+        (ev-occurrence-facts occs)
+        (map
+          (fn (b) (ev-booking-fact (first b) (first (rest b))))
+          bookings)))))
+
+;; Helper: insertion sort a list of (S E ...) lists ascending by S then E.
+(define
+  ev-list-before?
+  (fn
+    (a b)
+    (cond
+      ((< (first a) (first b)) true)
+      ((> (first a) (first b)) false)
+      (else (< (first (rest a)) (first (rest b)))))))
+
+(define
+  ev-list-insert
+  (fn
+    (x sorted)
+    (cond
+      ((empty? sorted) (list x))
+      ((ev-list-before? x (first sorted)) (cons x sorted))
+      (else (cons (first sorted) (ev-list-insert x (rest sorted)))))))
+
+(define
+  ev-sort-lists
+  (fn (xs) (reduce (fn (acc x) (ev-list-insert x acc)) (list) xs)))
+
+(define
+  ev-dedup-sorted
+  (fn
+    (xs)
+    (cond
+      ((empty? xs) xs)
+      ((empty? (rest xs)) xs)
+      ((= (first xs) (first (rest xs))) (ev-dedup-sorted (rest xs)))
+      (else (cons (first xs) (ev-dedup-sorted (rest xs)))))))
+
+;; All busy intervals (list S E) for an actor, ascending by start.
+(define
+  ev-busy
+  (fn
+    (db actor)
+    (let
+      ((rows (dl-query db (list (quote busy) actor (quote S) (quote E)))))
+      (ev-sort-lists (map (fn (b) (list (get b :S) (get b :E))) rows)))))
+
+;; Distinct conflicting occurrence-key pairs for an actor (each pair once).
+(define
+  ev-conflicts
+  (fn
+    (db actor)
+    (dl-query db (list (quote conflict) actor (quote O1) (quote O2)))))
+
+(define
+  ev-has-conflict?
+  (fn (db actor) (> (len (ev-conflicts db actor)) 0)))
+
+;; Is `actor` free across the whole window [qs,qe)? (no booked occurrence
+;; overlaps it). Asserts a transient qwindow fact, queries, retracts.
+(define
+  ev-free?
+  (fn
+    (db actor qs qe)
+    (do
+      (dl-assert! db (ev-qwindow-fact qs qe))
+      (let
+        ((rows (dl-query db (list (quote busy_in) actor (quote QS) (quote QE)))))
+        (begin (dl-retract! db (ev-qwindow-fact qs qe)) (empty? rows))))))
+
+;; ---- next-free slot search ----
+;; The earliest start s >= `after` such that [s, s+duration) is entirely free
+;; for `actor` and ends at or before `horizon`, or nil if none. The earliest
+;; such slot must begin either at `after` or immediately after some busy
+;; interval ends (classic interval packing), so those are the only candidates
+;; we probe — each probe reuses the busy_in rule via ev-free?.
+
+(define
+  ev-first-free
+  (fn
+    (db actor cands duration horizon)
+    (cond
+      ((empty? cands) nil)
+      (else
+        (let
+          ((s (first cands)))
+          (if
+            (and
+              (<= (+ s duration) horizon)
+              (ev-free? db actor s (+ s duration)))
+            s
+            (ev-first-free db actor (rest cands) duration horizon)))))))
+
+(define
+  ev-next-free
+  (fn
+    (db actor after duration horizon)
+    (let
+      ((ends (filter (fn (e) (>= e after)) (map (fn (iv) (first (rest iv))) (ev-busy db actor)))))
+      (ev-first-free
+        db
+        actor
+        (ev-dedup-sorted (sort (cons after ends)))
+        duration
+        horizon))))

lib/events/booking-notify.sx

@@ -0,0 +1,102 @@
+;; lib/events/booking-notify.sx — derive lifecycle notifications from the
+;; booking stream, for delivery via notify.sx.
+;;
+;; Walking the append-only booking stream yields one notification per state
+;; change, in order, classified by kind:
+;;
+;;   :booked      a confirmed booking
+;;   :promoted    a booking for an actor who was on the waitlist (auto-promote)
+;;   :held        a provisional hold (pending payment)
+;;   :confirmed   a held seat became confirmed (payment succeeded)
+;;   :released    a held seat was released (payment failed/expired)
+;;   :cancelled   a seat was given up
+;;   :waitlisted  an actor joined the waitlist
+;;
+;; Promotion is detected by folding the waitlist as we walk: a :booking for an
+;; actor currently on the waitlist is a promotion, not a fresh booking.
+;;
+;; Each notification's id is occ-key/seq (the stream seq is unique and stable),
+;; so re-deriving and re-delivering is idempotent — the notify transport dedups
+;; on this id and never double-pings.
+
+(define
+  ev-bn-kind
+  (fn
+    (typ promoted?)
+    (cond
+      ((= typ :hold) :held)
+      ((= typ :booking) (if promoted? :promoted :booked))
+      ((= typ :confirm) :confirmed)
+      ((= typ :cancel) :cancelled)
+      ((= typ :release) :released)
+      ((= typ :waitlist) :waitlisted)
+      (else nil))))
+
+(define
+  ev-bn-update-waiting
+  (fn
+    (typ actor waiting)
+    (cond
+      ((= typ :waitlist)
+        (if
+          (ev-bk-member? actor waiting)
+          waiting
+          (ev-bk-append waiting actor)))
+      ((= typ :unwaitlist) (ev-bk-remove waiting actor))
+      ((= typ :booking) (ev-bk-remove waiting actor))
+      ((= typ :hold) (ev-bk-remove waiting actor))
+      (else waiting))))
+
+(define ev-bn-mk (fn (occ-key label actor kind seq) {:id (str occ-key "/" seq) :event label :kind kind :recipient actor :seq seq}))
+
+(define
+  ev-bn-step
+  (fn
+    (occ-key label events waiting)
+    (if
+      (empty? events)
+      (list)
+      (let
+        ((e (first events)))
+        (let
+          ((typ (persist/event-type e))
+            (actor (get (persist/event-data e) :actor))
+            (seq (persist/event-seq e)))
+          (let
+            ((promoted? (and (= typ :booking) (ev-bk-member? actor waiting))))
+            (let
+              ((kind (ev-bn-kind typ promoted?))
+                (waiting2 (ev-bn-update-waiting typ actor waiting)))
+              (if
+                (nil? kind)
+                (ev-bn-step occ-key label (rest events) waiting2)
+                (cons
+                  (ev-bn-mk occ-key label actor kind seq)
+                  (ev-bn-step occ-key label (rest events) waiting2))))))))))
+
+;; The ordered lifecycle notifications for an occurrence's bookings. `label` is
+;; a human-facing event id carried on each notification.
+(define
+  ev/booking-notifications
+  (fn
+    (b occ-key label)
+    (ev-bn-step
+      occ-key
+      label
+      (persist/read b (ev-booking-stream occ-key))
+      (list))))
+
+;; Filter notifications to a single kind.
+(define
+  ev/notify-of-kind
+  (fn (notifs kind) (filter (fn (n) (= (get n :kind) kind)) notifs)))
+
+;; Project a notification to notify.sx's (id recipient body) wire shape.
+(define
+  ev/booking-notify->msg
+  (fn
+    (n)
+    (list
+      (get n :id)
+      (get n :recipient)
+      (list :booking-event (get n :kind) (get n :event)))))

lib/events/booking.sx

@@ -0,0 +1,372 @@
+;; lib/events/booking.sx — transactional, capacity-safe booking on persist.
+;;
+;; Each bookable occurrence has an append-only stream of booking events:
+;;
+;;   :booking  free booking — actor immediately holds a confirmed seat
+;;   :hold     provisional hold — seat reserved while payment is pending
+;;   :confirm  a held seat becomes confirmed (payment succeeded)
+;;   :release  a held seat is abandoned (payment failed/expired) — seat freed
+;;   :cancel   a held or confirmed seat is given up — seat freed
+;;
+;; The live state is the stream FOLDED in order into per-actor seat states
+;; (:held / :confirmed); an actor in ANY state occupies a seat, so both held and
+;; confirmed seats count toward capacity — a pending payment cannot be
+;; oversold. A freed seat (release/cancel) reopens capacity.
+;;
+;; Capacity safety is the contract: two writers racing for the last seat must
+;; NEVER both succeed. Seat-ACQUIRING writes (:booking, :hold) go through
+;; persist's optimistic concurrency — `persist/append-expect` appends only if
+;; the stream's last-seq still equals what the writer observed; else it returns
+;; a conflict the writer retries. Seat-FREEING writes (:cancel, :release) and
+;; the state transition (:confirm) never oversell, so they append directly.
+
+(define ev-booking-stream (fn (occ-key) (str "booking:" occ-key)))
+
+(define
+  ev-bk-member?
+  (fn
+    (x xs)
+    (cond
+      ((empty? xs) false)
+      ((= x (first xs)) true)
+      (else (ev-bk-member? x (rest xs))))))
+
+(define
+  ev-bk-index
+  (fn
+    (xs x i)
+    (cond
+      ((empty? xs) -1)
+      ((= (first xs) x) i)
+      (else (ev-bk-index (rest xs) x (+ i 1))))))
+
+(define ev-bk-append (fn (xs a) (append xs (list a))))
+(define ev-bk-remove (fn (xs a) (filter (fn (x) (not (= x a))) xs)))
+
+;; ---- per-actor state association list: ((actor state) ...) in join order ----
+
+(define
+  ev-state-has?
+  (fn
+    (states actor)
+    (cond
+      ((empty? states) false)
+      ((= (first (first states)) actor) true)
+      (else (ev-state-has? (rest states) actor)))))
+
+(define
+  ev-state-get
+  (fn
+    (states actor)
+    (cond
+      ((empty? states) :none)
+      ((= (first (first states)) actor) (first (rest (first states))))
+      (else (ev-state-get (rest states) actor)))))
+
+(define
+  ev-state-del
+  (fn (states actor) (filter (fn (p) (not (= (first p) actor))) states)))
+
+(define
+  ev-state-set
+  (fn
+    (states actor st)
+    (if
+      (ev-state-has? states actor)
+      (map (fn (p) (if (= (first p) actor) (list actor st) p)) states)
+      (append states (list (list actor st))))))
+
+;; Fold the booking stream into per-actor seat states (join order preserved).
+(define
+  ev-fold-states
+  (fn
+    (events)
+    (reduce
+      (fn
+        (acc e)
+        (let
+          ((typ (persist/event-type e))
+            (actor (get (persist/event-data e) :actor)))
+          (cond
+            ((= typ :booking) (ev-state-set acc actor :confirmed))
+            ((= typ :hold) (ev-state-set acc actor :held))
+            ((= typ :confirm)
+              (if
+                (ev-state-has? acc actor)
+                (ev-state-set acc actor :confirmed)
+                acc))
+            ((= typ :cancel) (ev-state-del acc actor))
+            ((= typ :release) (ev-state-del acc actor))
+            (else acc))))
+      (list)
+      events)))
+
+(define
+  ev-states-of
+  (fn
+    (b occ-key)
+    (ev-fold-states (persist/read b (ev-booking-stream occ-key)))))
+
+;; Live roster (actors holding a seat — held or confirmed), oldest active first.
+(define
+  ev-booked-actors
+  (fn (b occ-key) (map (fn (p) (first p)) (ev-states-of b occ-key))))
+
+(define
+  ev-actor-booked?
+  (fn (b occ-key actor) (ev-bk-member? actor (ev-booked-actors b occ-key))))
+
+;; Live seat count (folded roster size — both held and confirmed seats).
+(define
+  ev-booking-count
+  (fn (b occ-key) (len (ev-booked-actors b occ-key))))
+
+;; Seat state for an actor: :held / :confirmed / :none.
+(define
+  ev/seat-state
+  (fn (b occ-key actor) (ev-state-get (ev-states-of b occ-key) actor)))
+
+;; 1-based seat number for an actor on the roster (0 if not booked).
+(define
+  ev-seat-of
+  (fn
+    (actors actor)
+    (let
+      ((i (ev-bk-index actors actor 0)))
+      (if (< i 0) 0 (+ i 1)))))
+
+;; ---- seat-acquiring writes (capacity-guarded via append-expect) ----
+
+;; One seat-acquiring attempt of `kind` (:booking or :hold) against an OBSERVED
+;; snapshot (roster the writer saw + the last-seq). Returns :already / :full /
+;; :conflict, or a success dict tagged with `ok-status`. :conflict means a
+;; concurrent append landed since the snapshot — the caller must re-observe.
+(define
+  ev-acquire-with-observed
+  (fn
+    (b occ-key capacity actor observed-actors expected kind ok-status)
+    (cond
+      ((ev-bk-member? actor observed-actors) {:seat (ev-seat-of observed-actors actor) :actor actor :status :already})
+      ((>= (len observed-actors) capacity) {:actor actor :capacity capacity :status :full})
+      (else
+        (let
+          ((r (persist/append-expect b (ev-booking-stream occ-key) expected kind 0 {:actor actor})))
+          (if (persist/conflict? r) {:actual (persist/conflict-actual r) :actor actor :status :conflict} {:seat (+ (len observed-actors) 1) :actor actor :status ok-status}))))))
+
+(define
+  ev-acquire!
+  (fn
+    (b occ-key capacity actor kind ok-status)
+    (let
+      ((res (ev-acquire-with-observed b occ-key capacity actor (ev-booked-actors b occ-key) (persist/last-seq b (ev-booking-stream occ-key)) kind ok-status)))
+      (if
+        (= (get res :status) :conflict)
+        (ev-acquire! b occ-key capacity actor kind ok-status)
+        res))))
+
+;; Capacity-safe confirmed booking (retrying on conflict).
+(define
+  ev/book!
+  (fn
+    (b occ-key capacity actor)
+    (ev-acquire! b occ-key capacity actor :booking :booked)))
+
+;; Capacity-safe provisional hold (retrying on conflict). The seat is reserved
+;; (counts toward capacity) until confirmed or released.
+(define
+  ev/hold!
+  (fn
+    (b occ-key capacity actor)
+    (ev-acquire! b occ-key capacity actor :hold :held)))
+
+;; Test seam: one attempt against a caller-supplied snapshot (book or hold).
+(define
+  ev/book-with-observed
+  (fn
+    (b occ-key capacity actor observed-actors expected)
+    (ev-acquire-with-observed
+      b
+      occ-key
+      capacity
+      actor
+      observed-actors
+      expected
+      :booking :booked)))
+
+(define
+  ev/hold-with-observed
+  (fn
+    (b occ-key capacity actor observed-actors expected)
+    (ev-acquire-with-observed
+      b
+      occ-key
+      capacity
+      actor
+      observed-actors
+      expected
+      :hold :held)))
+
+;; ---- state transitions / seat-freeing writes (no oversell, append direct) ----
+
+;; Confirm a held seat (payment succeeded). :confirmed on success,
+;; :already-confirmed if it was confirmed, :not-held otherwise.
+(define
+  ev/confirm!
+  (fn
+    (b occ-key actor)
+    (let
+      ((st (ev/seat-state b occ-key actor)))
+      (cond
+        ((= st :held)
+          (begin
+            (persist/append
+              b
+              (ev-booking-stream occ-key)
+              :confirm 0
+              {:actor actor})
+            {:actor actor :status :confirmed}))
+        ((= st :confirmed) {:actor actor :status :already-confirmed})
+        (else {:actor actor :status :not-held})))))
+
+;; Release a held seat (payment failed/expired), freeing it. Only valid for a
+;; held seat — confirmed bookings are given up via ev/cancel!.
+(define
+  ev/release!
+  (fn
+    (b occ-key actor)
+    (let
+      ((st (ev/seat-state b occ-key actor)))
+      (if
+        (= st :held)
+        (begin
+          (persist/append
+            b
+            (ev-booking-stream occ-key)
+            :release 0
+            {:actor actor})
+          {:actor actor :status :released})
+        {:actor actor :status :not-held}))))
+
+;; Cancel a held or confirmed seat, freeing it. :cancelled or :not-booked.
+(define
+  ev/cancel!
+  (fn
+    (b occ-key actor)
+    (if
+      (ev-bk-member? actor (ev-booked-actors b occ-key))
+      (begin
+        (persist/append
+          b
+          (ev-booking-stream occ-key)
+          :cancel 0
+          {:actor actor})
+        {:actor actor :status :cancelled})
+      {:actor actor :status :not-booked})))
+
+;; The roster as a plain list of actors (oldest active first).
+(define ev/roster (fn (b occ-key) (ev-booked-actors b occ-key)))
+
+;; Seats remaining for an occurrence of the given capacity.
+(define
+  ev/seats-left
+  (fn
+    (b occ-key capacity)
+    (max 0 (- capacity (ev-booking-count b occ-key)))))
+
+;; ---- waitlist ----
+;; When an occurrence is full, actors join a FIFO waitlist (:waitlist /
+;; :unwaitlist events on the same stream). Taking a seat (:booking / :hold)
+;; removes an actor from the queue, so the waitlist fold is independent of the
+;; seat fold. Cancelling/releasing a seat can auto-promote the head of the
+;; queue (a :booking appended for them).
+
+(define
+  ev-fold-waiting
+  (fn
+    (events)
+    (reduce
+      (fn
+        (acc e)
+        (let
+          ((typ (persist/event-type e))
+            (actor (get (persist/event-data e) :actor)))
+          (cond
+            ((= typ :waitlist) (if (ev-bk-member? actor acc) acc (ev-bk-append acc actor)))
+            ((= typ :unwaitlist) (ev-bk-remove acc actor))
+            ((= typ :booking) (ev-bk-remove acc actor))
+            ((= typ :hold) (ev-bk-remove acc actor))
+            (else acc))))
+      (list)
+      events)))
+
+;; The current waitlist queue (FIFO, oldest first).
+(define
+  ev/waitlist
+  (fn (b occ-key) (ev-fold-waiting (persist/read b (ev-booking-stream occ-key)))))
+
+;; 1-based queue position for an actor (0 if not waiting).
+(define
+  ev/waitlist-position
+  (fn (b occ-key actor) (ev-seat-of (ev/waitlist b occ-key) actor)))
+
+;; Book if a seat is free, else join the waitlist. Idempotent: already seated →
+;; :already; already queued → :already-waiting.
+(define
+  ev/waitlist!
+  (fn
+    (b occ-key capacity actor)
+    (let
+      ((seats (ev-booked-actors b occ-key))
+        (waiting (ev/waitlist b occ-key)))
+      (cond
+        ((ev-bk-member? actor seats)
+          {:status :already :seat (ev-seat-of seats actor) :actor actor})
+        ((ev-bk-member? actor waiting)
+          {:status :already-waiting :position (ev-seat-of waiting actor) :actor actor})
+        (else
+          (let
+            ((r (ev/book! b occ-key capacity actor)))
+            (if
+              (= (get r :status) :booked)
+              r
+              (begin
+                (persist/append b (ev-booking-stream occ-key) :waitlist 0 {:actor actor})
+                {:status :waitlisted
+                  :position (+ (len waiting) 1)
+                  :actor actor}))))))))
+
+;; Leave the waitlist. :left or :not-waiting.
+(define
+  ev/leave-waitlist!
+  (fn
+    (b occ-key actor)
+    (if
+      (ev-bk-member? actor (ev/waitlist b occ-key))
+      (begin
+        (persist/append b (ev-booking-stream occ-key) :unwaitlist 0 {:actor actor})
+        {:status :left :actor actor})
+      {:status :not-waiting :actor actor})))
+
+;; Cancel a seat and, if that frees capacity, auto-promote the head of the
+;; waitlist (a confirmed booking). Returns the cancel result plus :promoted
+;; (the actor promoted, or nil).
+(define
+  ev/cancel-promote!
+  (fn
+    (b occ-key capacity actor)
+    (let
+      ((c (ev/cancel! b occ-key actor)))
+      (if
+        (= (get c :status) :cancelled)
+        (let
+          ((waiting (ev/waitlist b occ-key))
+            (seats (ev-booked-actors b occ-key)))
+          (if
+            (and (not (empty? waiting)) (< (len seats) capacity))
+            (let
+              ((promoted (first waiting)))
+              (begin
+                (persist/append b (ev-booking-stream occ-key) :booking 0 {:actor promoted})
+                {:status :cancelled :actor actor :promoted promoted}))
+            {:status :cancelled :actor actor :promoted nil}))
+        c))))

lib/events/calendar.sx

@@ -0,0 +1,601 @@
+;; lib/events/calendar.sx — civil date arithmetic + RRULE expansion in a window.
+;;
+;; Datetimes are integer "epoch minutes": days-since-1970-01-01 * 1440 plus
+;; minute-of-day. Ordering, window bounds, and durations are plain integer
+;; arithmetic. Civil <-> day-number conversion uses Howard Hinnant's algorithm
+;; (exact, branch-free, correct for the proleptic Gregorian calendar).
+;;
+;; RRULE expansion is the bridge to Datalog: a recurring event expands to a
+;; bounded list of occurrence dicts within an explicit (win-start, win-end)
+;; window. Expansion is ALWAYS windowed — an RRULE without a window is an
+;; infinite computation and is never permitted. Supported subset (RFC 5545):
+;; FREQ=DAILY|WEEKLY|MONTHLY, INTERVAL, COUNT, UNTIL, BYDAY (weekly: weekday
+;; numbers; monthly: {:ord N :wd W} ordinal weekdays), BYMONTHDAY (monthly,
+;; negative = from month end). YEARLY and the rest are deferred.
+
+;; ---- integer helpers ----
+
+;; Floored integer division (modulo is already floored, so the remainder
+;; subtraction makes the quotient exact and floor-correct for any sign).
+(define ev-floor-div (fn (a b) (quotient (- a (modulo a b)) b)))
+
+(define ev-or (fn (x d) (if (nil? x) d x)))
+
+(define ev-filter-nil (fn (xs) (filter (fn (x) (not (nil? x))) xs)))
+
+;; ---- civil date core (Hinnant) ----
+
+;; Days since 1970-01-01 for civil (y, m, d). m in [1,12], d in [1,31].
+(define
+  ev-days-from-civil
+  (fn
+    (y0 m d)
+    (let
+      ((y (if (<= m 2) (- y0 1) y0)))
+      (let
+        ((era (ev-floor-div (if (>= y 0) y (- y 399)) 400)))
+        (let
+          ((yoe (- y (* era 400)))
+            (doy
+              (+
+                (ev-floor-div
+                  (+
+                    (*
+                      153
+                      (+ m (if (> m 2) -3 9)))
+                    2)
+                  5)
+                (- d 1))))
+          (let
+            ((doe (+ (* yoe 365) (ev-floor-div yoe 4) (- (ev-floor-div yoe 100)) doy)))
+            (+ (* era 146097) doe -719468)))))))
+
+;; Civil (y m d) list from a day-number.
+(define
+  ev-civil-from-days
+  (fn
+    (z0)
+    (let
+      ((z (+ z0 719468)))
+      (let
+        ((era (ev-floor-div (if (>= z 0) z (- z 146096)) 146097)))
+        (let
+          ((doe (- z (* era 146097))))
+          (let
+            ((yoe (ev-floor-div (+ (- doe (ev-floor-div doe 1460)) (ev-floor-div doe 36524) (- (ev-floor-div doe 146096))) 365)))
+            (let
+              ((y (+ yoe (* era 400)))
+                (doy
+                  (-
+                    doe
+                    (+
+                      (* 365 yoe)
+                      (ev-floor-div yoe 4)
+                      (- (ev-floor-div yoe 100))))))
+              (let
+                ((mp (ev-floor-div (+ (* 5 doy) 2) 153)))
+                (let
+                  ((d (+ (- doy (ev-floor-div (+ (* 153 mp) 2) 5)) 1))
+                    (m
+                      (if
+                        (< mp 10)
+                        (+ mp 3)
+                        (- mp 9))))
+                  (list (if (<= m 2) (+ y 1) y) m d))))))))))
+
+;; Weekday of a day-number: 0=Mon .. 6=Sun (1970-01-01 is Thursday = 3).
+(define ev-weekday-of-days (fn (z) (modulo (+ z 3) 7)))
+
+(define
+  ev-days-in-month
+  (fn
+    (y m)
+    (-
+      (ev-days-from-civil
+        (if (= m 12) (+ y 1) y)
+        (if (= m 12) 1 (+ m 1))
+        1)
+      (ev-days-from-civil y m 1))))
+
+;; Add k months to (y,m), returning (list y2 m2).
+(define
+  ev-add-months
+  (fn
+    (y m k)
+    (let
+      ((total (+ (* y 12) (- m 1) k)))
+      (list
+        (ev-floor-div total 12)
+        (+ (modulo total 12) 1)))))
+
+;; ---- datetime (epoch minutes) ----
+
+(define
+  ev-dt
+  (fn
+    (y m d hh mm)
+    (+ (* (ev-days-from-civil y m d) 1440) (* hh 60) mm)))
+
+(define ev-date (fn (y m d) (ev-dt y m d 0 0)))
+
+(define ev-dt->days (fn (t) (ev-floor-div t 1440)))
+
+(define ev-dt->civil (fn (t) (ev-civil-from-days (ev-dt->days t))))
+
+(define ev-dt-weekday (fn (t) (ev-weekday-of-days (ev-dt->days t))))
+
+(define ev-dt-tod (fn (t) (modulo t 1440)))
+
+(define ev-civ-y (fn (c) (first c)))
+(define ev-civ-m (fn (c) (first (rest c))))
+(define ev-civ-d (fn (c) (first (rest (rest c)))))
+
+;; ---- event + occurrence constructors ----
+
+;; rrule is nil (single event) or a dict:
+;;   {:freq :daily|:weekly|:monthly :interval N :count N|nil :until DT|nil
+;;    :byday ...|nil :bymonthday (list 15 -1)|nil}
+;;   weekly  :byday -> (list 0 2 4)            weekday numbers, 0=Mon
+;;   monthly :byday -> (list {:ord 2 :wd 1})   nth weekday (ord<0 from end)
+;;   monthly :bymonthday -> (list 15 -1)       day of month (negative from end)
+(define ev-event (fn (id dtstart duration rrule capacity) {:duration duration :id id :dtstart dtstart :capacity capacity :rrule rrule}))
+
+;; Event with EXDATE/RDATE exceptions. exdate/rdate are lists of epoch-minute
+;; starts to exclude from / add to the expansion (RFC 5545 VEVENT properties).
+(define
+  ev-event-full
+  (fn
+    (id dtstart duration rrule capacity exdate rdate)
+    {:duration duration
+      :id id
+      :dtstart dtstart
+      :capacity capacity
+      :rrule rrule
+      :exdate exdate
+      :rdate rdate}))
+
+(define ev-occ (fn (id start dur) {:id id :start start :end (+ start dur)}))
+
+;; ---- DAILY expansion ----
+;; occ starts at dtstart; n counts every generated occurrence (window-
+;; independent, so COUNT/UNTIL bound the rule, not the view). Emits only
+;; occurrences inside [win-start, win-end].
+(define
+  ev-daily-loop
+  (fn
+    (id occ duration step count until dtstart win-start win-end acc n)
+    (cond
+      ((> occ win-end) acc)
+      ((and (not (nil? count)) (>= n count)) acc)
+      ((and (not (nil? until)) (> occ until)) acc)
+      (else
+        (begin
+          (when (>= occ win-start) (append! acc (ev-occ id occ duration)))
+          (ev-daily-loop
+            id
+            (+ occ step)
+            duration
+            step
+            count
+            until
+            dtstart
+            win-start
+            win-end
+            acc
+            (+ n 1)))))))
+
+;; ---- shared per-period emit ----
+;; Walk a start-ascending list of candidate occurrence datetimes for one
+;; period, generating (count toward COUNT) those >= dtstart within UNTIL, and
+;; emitting those also inside the window. Returns the updated running n.
+(define
+  ev-emit-occs
+  (fn
+    (id occs duration count until dtstart win-start win-end acc n)
+    (if
+      (empty? occs)
+      n
+      (let
+        ((occ (first occs)))
+        (let
+          ((generates? (and (>= occ dtstart) (or (nil? until) (<= occ until)) (or (nil? count) (< n count)))))
+          (begin
+            (when
+              (and generates? (>= occ win-start) (<= occ win-end))
+              (append! acc (ev-occ id occ duration)))
+            (ev-emit-occs
+              id
+              (rest occs)
+              duration
+              count
+              until
+              dtstart
+              win-start
+              win-end
+              acc
+              (if generates? (+ n 1) n))))))))
+
+;; ---- WEEKLY expansion ----
+;; Iterate week by week from the Monday of dtstart's week; within each active
+;; week emit each BYDAY (sorted). n counts every generated occurrence.
+
+(define
+  ev-week0-days
+  (fn (dtstart) (- (ev-dt->days dtstart) (ev-dt-weekday dtstart))))
+
+(define
+  ev-byday-default
+  (fn
+    (byday dtstart)
+    (if (nil? byday) (list (ev-dt-weekday dtstart)) (sort byday))))
+
+(define
+  ev-weekly-loop
+  (fn
+    (id
+      week-days
+      tod
+      duration
+      week-step
+      bd
+      count
+      until
+      dtstart
+      win-start
+      win-end
+      acc
+      n)
+    (let
+      ((week-start-dt (* week-days 1440)))
+      (cond
+        ((> week-start-dt win-end) acc)
+        ((and (not (nil? count)) (>= n count)) acc)
+        (else
+          (let
+            ((occs (map (fn (wd) (+ (* (+ week-days wd) 1440) tod)) bd)))
+            (let
+              ((n2 (ev-emit-occs id occs duration count until dtstart win-start win-end acc n)))
+              (ev-weekly-loop
+                id
+                (+ week-days week-step)
+                tod
+                duration
+                week-step
+                bd
+                count
+                until
+                dtstart
+                win-start
+                win-end
+                acc
+                n2))))))))
+
+;; ---- MONTHLY expansion ----
+;; Iterate month by month from dtstart's month, stepping by INTERVAL months.
+;; Candidate days per month come from BYMONTHDAY, then ordinal BYDAY, else the
+;; day-of-month of dtstart (skipped in months too short to contain it).
+
+;; Resolve a BYMONTHDAY value to a valid day-of-month, or nil.
+(define
+  ev-resolve-monthday
+  (fn
+    (y m bmd)
+    (let
+      ((dim (ev-days-in-month y m)))
+      (let
+        ((day (if (< bmd 0) (+ dim 1 bmd) bmd)))
+        (if (and (>= day 1) (<= day dim)) day nil)))))
+
+;; Resolve an ordinal weekday {:ord :wd} to a day-of-month, or nil.
+(define
+  ev-resolve-nth-weekday
+  (fn
+    (y m ord wd)
+    (let
+      ((dim (ev-days-in-month y m)))
+      (if
+        (> ord 0)
+        (let
+          ((first-wd (ev-weekday-of-days (ev-days-from-civil y m 1))))
+          (let
+            ((day (+ 1 (modulo (- wd first-wd) 7) (* (- ord 1) 7))))
+            (if (<= day dim) day nil)))
+        (let
+          ((last-wd (ev-weekday-of-days (ev-days-from-civil y m dim))))
+          (let
+            ((day (- dim (modulo (- last-wd wd) 7) (* (- (- ord) 1) 7))))
+            (if (>= day 1) day nil)))))))
+
+(define
+  ev-month-candidates
+  (fn
+    (y m rrule dtstart)
+    (let
+      ((bmd (get rrule :bymonthday)) (byday (get rrule :byday)))
+      (cond
+        ((not (nil? bmd))
+          (ev-filter-nil (map (fn (d) (ev-resolve-monthday y m d)) bmd)))
+        ((not (nil? byday))
+          (ev-filter-nil
+            (map
+              (fn
+                (e)
+                (ev-resolve-nth-weekday y m (get e :ord) (get e :wd)))
+              byday)))
+        (else
+          (ev-filter-nil
+            (list
+              (ev-resolve-monthday y m (ev-civ-d (ev-dt->civil dtstart))))))))))
+
+(define
+  ev-monthly-loop
+  (fn
+    (id
+      y
+      m
+      rrule
+      duration
+      tod
+      interval
+      count
+      until
+      dtstart
+      win-start
+      win-end
+      acc
+      n)
+    (let
+      ((month-start (ev-dt y m 1 0 0)))
+      (cond
+        ((> month-start win-end) acc)
+        ((and (not (nil? count)) (>= n count)) acc)
+        (else
+          (let
+            ((days (sort (ev-month-candidates y m rrule dtstart))))
+            (let
+              ((occs (map (fn (d) (+ (* (ev-days-from-civil y m d) 1440) tod)) days)))
+              (let
+                ((n2 (ev-emit-occs id occs duration count until dtstart win-start win-end acc n))
+                  (nm (ev-add-months y m interval)))
+                (ev-monthly-loop
+                  id
+                  (ev-civ-y nm)
+                  (ev-civ-m nm)
+                  rrule
+                  duration
+                  tod
+                  interval
+                  count
+                  until
+                  dtstart
+                  win-start
+                  win-end
+                  acc
+                  n2)))))))))
+
+;; ---- top-level expansion ----
+;; Raw expansion (RRULE / single event), before EXDATE/RDATE are applied.
+;; Returns a list of occurrence dicts {:id :start :end} within the window.
+(define
+  ev-expand-base
+  (fn
+    (event win-start win-end)
+    (let
+      ((id (get event :id))
+        (dtstart (get event :dtstart))
+        (duration (get event :duration))
+        (rrule (get event :rrule)))
+      (if
+        (nil? rrule)
+        (if
+          (and (>= dtstart win-start) (<= dtstart win-end))
+          (list (ev-occ id dtstart duration))
+          (list))
+        (let
+          ((freq (get rrule :freq))
+            (interval (ev-or (get rrule :interval) 1))
+            (count (get rrule :count))
+            (until (get rrule :until))
+            (byday (get rrule :byday))
+            (acc (list)))
+          (begin
+            (cond
+              ((= freq :daily)
+                (ev-daily-loop
+                  id
+                  dtstart
+                  duration
+                  (* interval 1440)
+                  count
+                  until
+                  dtstart
+                  win-start
+                  win-end
+                  acc
+                  0))
+              ((= freq :weekly)
+                (ev-weekly-loop
+                  id
+                  (ev-week0-days dtstart)
+                  (ev-dt-tod dtstart)
+                  duration
+                  (* interval 7)
+                  (ev-byday-default byday dtstart)
+                  count
+                  until
+                  dtstart
+                  win-start
+                  win-end
+                  acc
+                  0))
+              ((= freq :monthly)
+                (let
+                  ((civ (ev-dt->civil dtstart)))
+                  (ev-monthly-loop
+                    id
+                    (ev-civ-y civ)
+                    (ev-civ-m civ)
+                    rrule
+                    duration
+                    (ev-dt-tod dtstart)
+                    interval
+                    count
+                    until
+                    dtstart
+                    win-start
+                    win-end
+                    acc
+                    0)))
+              (else (error (str "ev-expand-base: unsupported freq: " freq))))
+            acc))))))
+
+;; ---- EXDATE / RDATE (RFC 5545 exceptions) ----
+;; Applied AFTER raw expansion: RDATE adds explicit occurrences within the
+;; window, EXDATE removes occurrences whose start matches (EXDATE wins over
+;; RDATE). Both are VEVENT-level: (get event :exdate) / (get event :rdate) are
+;; lists of epoch-minute starts; nil for plain events.
+
+(define
+  ev-num-member?
+  (fn
+    (n xs)
+    (cond
+      ((empty? xs) false)
+      ((= n (first xs)) true)
+      (else (ev-num-member? n (rest xs))))))
+
+;; Drop duplicate-start occurrences from a start-sorted list (keep one).
+(define
+  ev-dedupe-by-start
+  (fn
+    (occs)
+    (cond
+      ((empty? occs) occs)
+      ((empty? (rest occs)) occs)
+      ((= (get (first occs) :start) (get (first (rest occs)) :start))
+        (ev-dedupe-by-start (rest occs)))
+      (else (cons (first occs) (ev-dedupe-by-start (rest occs)))))))
+
+(define
+  ev-apply-exceptions
+  (fn
+    (event base win-start win-end)
+    (let
+      ((id (get event :id))
+        (duration (get event :duration))
+        (exdate (ev-or (get event :exdate) (list)))
+        (rdate (ev-or (get event :rdate) (list))))
+      (let
+        ((rdate-occs
+           (reduce
+             (fn
+               (acc d)
+               (if
+                 (and (>= d win-start) (<= d win-end))
+                 (cons (ev-occ id d duration) acc)
+                 acc))
+             (list)
+             rdate)))
+        (let
+          ((no-ex
+             (filter
+               (fn (o) (not (ev-num-member? (get o :start) exdate)))
+               (append base rdate-occs))))
+          (ev-dedupe-by-start (ev-sort-occs no-ex)))))))
+
+;; ---- per-occurrence overrides (RFC 5545 RECURRENCE-ID) ----
+;; A single instance of a recurring series can be detached and rescheduled. The
+;; event carries :overrides — a list of (orig-start {:start :duration}) — keyed
+;; by the occurrence's ORIGINAL start. Applied after EXDATE/RDATE. A moved
+;; instance whose new start leaves the window is dropped from this window (the
+;; original slot is vacated); an instance moved INTO the window from outside is
+;; out of scope for a windowed expansion (known stub limitation).
+
+(define
+  ev-assoc-lookup
+  (fn
+    (k pairs)
+    (cond
+      ((empty? pairs) nil)
+      ((= (first (first pairs)) k) (first (rest (first pairs))))
+      (else (ev-assoc-lookup k (rest pairs))))))
+
+(define
+  ev-apply-overrides
+  (fn
+    (id base overrides)
+    (map
+      (fn
+        (o)
+        (let
+          ((ov (ev-assoc-lookup (get o :start) overrides)))
+          (if (nil? ov) o (ev-occ id (get ov :start) (get ov :duration)))))
+      base)))
+
+;; Add an override that reschedules the occurrence originally at `orig-start`
+;; to `new-start` with `new-duration`.
+(define
+  ev-with-override
+  (fn
+    (event orig-start new-start new-duration)
+    (assoc
+      event
+      :overrides
+      (cons
+        (list orig-start {:start new-start :duration new-duration})
+        (ev-or (get event :overrides) (list))))))
+
+;; Expand an event into occurrence dicts within the window, applying any
+;; EXDATE/RDATE exceptions and per-occurrence overrides. Public entry point.
+(define
+  ev-expand
+  (fn
+    (event win-start win-end)
+    (let
+      ((excepted
+         (ev-apply-exceptions
+           event
+           (ev-expand-base event win-start win-end)
+           win-start
+           win-end))
+        (overrides (ev-or (get event :overrides) (list)))
+        (id (get event :id)))
+      (if
+        (empty? overrides)
+        excepted
+        (filter
+          (fn (o) (and (>= (get o :start) win-start) (<= (get o :start) win-end)))
+          (ev-sort-occs (ev-apply-overrides id excepted overrides)))))))
+
+;; ---- multi-event expansion (sorted by start) ----
+
+;; Insertion of one occurrence into a start-ascending list.
+(define
+  ev-occ-insert
+  (fn
+    (o sorted)
+    (cond
+      ((empty? sorted) (list o))
+      ((<= (get o :start) (get (first sorted) :start)) (cons o sorted))
+      (else (cons (first sorted) (ev-occ-insert o (rest sorted)))))))
+
+(define
+  ev-sort-occs
+  (fn (occs) (reduce (fn (acc o) (ev-occ-insert o acc)) (list) occs)))
+
+;; Expand many events into one occurrence list, ascending by start.
+(define
+  ev-expand-all
+  (fn
+    (events win-start win-end)
+    (let
+      ((acc (list)))
+      (begin
+        (for-each
+          (fn
+            (ev)
+            (for-each
+              (fn (o) (append! acc o))
+              (ev-expand ev win-start win-end)))
+          events)
+        (ev-sort-occs acc)))))

lib/events/conformance.conf

@@ -0,0 +1,58 @@
+# events-on-sx conformance config — sourced by lib/guest/conformance.sh.
+
+LANG_NAME=events
+MODE=dict
+SCOREBOARD_DIR=lib/events
+
+PRELOADS=(
+  spec/stdlib.sx
+  lib/r7rs.sx
+  lib/datalog/tokenizer.sx
+  lib/datalog/parser.sx
+  lib/datalog/unify.sx
+  lib/datalog/db.sx
+  lib/datalog/builtins.sx
+  lib/datalog/aggregates.sx
+  lib/datalog/strata.sx
+  lib/datalog/eval.sx
+  lib/datalog/api.sx
+  lib/datalog/magic.sx
+  lib/events/calendar.sx
+  lib/events/availability.sx
+  lib/persist/event.sx
+  lib/persist/backend.sx
+  lib/persist/log.sx
+  lib/persist/kv.sx
+  lib/persist/concurrency.sx
+  lib/persist/api.sx
+  lib/events/booking.sx
+  lib/events/booking-notify.sx
+  lib/events/ticket.sx
+  lib/guest/lex.sx
+  lib/guest/reflective/env.sx
+  lib/guest/reflective/quoting.sx
+  lib/scheme/parser.sx
+  lib/scheme/eval.sx
+  lib/scheme/runtime.sx
+  lib/flow/spec.sx
+  lib/flow/store.sx
+  lib/flow/remote.sx
+  lib/flow/host.sx
+  lib/flow/api.sx
+  lib/events/notify.sx
+  lib/events/api.sx
+  lib/events/reminders.sx
+  lib/events/federation.sx
+)
+
+SUITES=(
+  "calendar:lib/events/tests/calendar.sx:(ev-calendar-tests-run!)"
+  "availability:lib/events/tests/availability.sx:(ev-availability-tests-run!)"
+  "api:lib/events/tests/api.sx:(ev-api-tests-run!)"
+  "booking:lib/events/tests/booking.sx:(ev-booking-tests-run!)"
+  "booking-notify:lib/events/tests/booking-notify.sx:(ev-booking-notify-tests-run!)"
+  "ticket:lib/events/tests/ticket.sx:(ev-ticket-tests-run!)"
+  "notify:lib/events/tests/notify.sx:(ev-notify-tests-run!)"
+  "reminders:lib/events/tests/reminders.sx:(ev-reminders-tests-run!)"
+  "federation:lib/events/tests/federation.sx:(ev-federation-tests-run!)"
+)

lib/events/conformance.sh

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

lib/events/federation.sx

@@ -0,0 +1,165 @@
+;; lib/events/federation.sx — cross-instance calendar federation (trust-gated).
+;;
+;; A peer is another events instance that publishes a schedule (an events
+;; store). We merge a peer's agenda into ours ONLY if we trust it — trust is a
+;; set of peer ids, re-checked on every merge, so revoking a peer takes effect
+;; immediately. Merged occurrences carry :origin provenance (:local for ours, or
+;; the peer id) so a consumer always knows where a slot came from.
+;;
+;; This is the trust-gated stub: peers publish plain schedules and we fold the
+;; trusted ones into a single sorted agenda. Real transport (fed-sx / signed
+;; fetch) slots in behind `ev/peer-agenda` without changing the merge.
+;;
+;; Federated FREE/BUSY follows the iCal model: a peer publishes BUSY intervals
+;; for an actor (not event details — privacy-preserving), and we union local +
+;; trusted-peer busy to answer "is this actor free?" across instances.
+
+(define ev/peer (fn (id store) {:id id :busy (list) :store store}))
+
+;; A peer that also publishes free/busy: `busy` is a list of
+;; (actor ((start end) ...)) pairs.
+(define ev/peer-with-busy (fn (id store busy) {:id id :busy busy :store store}))
+
+(define ev/peer-id (fn (p) (get p :id)))
+(define ev/peer-store (fn (p) (get p :store)))
+(define ev/peer-busy-table (fn (p) (get p :busy)))
+
+(define
+  ev-fed-member?
+  (fn
+    (x xs)
+    (cond
+      ((empty? xs) false)
+      ((= x (first xs)) true)
+      (else (ev-fed-member? x (rest xs))))))
+
+;; Do we trust this peer id? (trust is a list of trusted peer ids.)
+(define ev/trusts? (fn (trust peer-id) (ev-fed-member? peer-id trust)))
+
+;; The trusted subset of a peer list.
+(define
+  ev/trusted-peers
+  (fn
+    (peers trust)
+    (filter (fn (p) (ev/trusts? trust (ev/peer-id p))) peers)))
+
+;; Tag occurrences with provenance.
+(define ev-tag-origin (fn (occs origin) (map (fn (o) {:id (get o :id) :start (get o :start) :end (get o :end) :origin origin}) occs)))
+
+;; A peer's agenda over [ws, we), tagged with the peer's id as :origin.
+(define
+  ev/peer-agenda
+  (fn
+    (peer ws we)
+    (ev-tag-origin (ev/agenda (ev/peer-store peer) ws we) (ev/peer-id peer))))
+
+;; ---- merge (sorted by start, then origin for ties) ----
+
+(define
+  ev-fed-before?
+  (fn
+    (a c)
+    (cond
+      ((< (get a :start) (get c :start)) true)
+      ((> (get a :start) (get c :start)) false)
+      (else (< (str (get a :origin)) (str (get c :origin)))))))
+
+(define
+  ev-fed-insert
+  (fn
+    (x sorted)
+    (cond
+      ((empty? sorted) (list x))
+      ((ev-fed-before? x (first sorted)) (cons x sorted))
+      (else (cons (first sorted) (ev-fed-insert x (rest sorted)))))))
+
+(define
+  ev-fed-sort
+  (fn (xs) (reduce (fn (acc x) (ev-fed-insert x acc)) (list) xs)))
+
+;; Local agenda (origin :local) merged with every TRUSTED peer's agenda,
+;; sorted by start. Untrusted peers contribute nothing.
+(define
+  ev/federated-agenda
+  (fn
+    (local-store peers trust ws we)
+    (let
+      ((acc (list)))
+      (begin
+        (for-each
+          (fn (o) (append! acc o))
+          (ev-tag-origin (ev/agenda local-store ws we) :local))
+        (for-each
+          (fn
+            (peer)
+            (when
+              (ev/trusts? trust (ev/peer-id peer))
+              (for-each
+                (fn (o) (append! acc o))
+                (ev/peer-agenda peer ws we))))
+          peers)
+        (ev-fed-sort acc)))))
+
+;; Filter a federated agenda to occurrences from one origin.
+(define
+  ev/from-origin
+  (fn
+    (agenda origin)
+    (filter (fn (o) (= (get o :origin) origin)) agenda)))
+
+;; ---- federated free/busy ----
+
+;; A peer's published busy intervals for `actor` ((start end) ...), or empty.
+(define
+  ev/peer-busy
+  (fn
+    (peer actor)
+    (let
+      ((row (ev-fed-assoc actor (ev/peer-busy-table peer))))
+      (if (nil? row) (list) (first (rest row))))))
+
+(define
+  ev-fed-assoc
+  (fn
+    (k pairs)
+    (cond
+      ((empty? pairs) nil)
+      ((= (first (first pairs)) k) (first pairs))
+      (else (ev-fed-assoc k (rest pairs))))))
+
+;; All busy intervals for `actor` across the LOCAL availability db plus every
+;; TRUSTED peer's published free/busy, merged and sorted by start.
+;; `local-db` is an availability db (see availability.sx ev-build-avail).
+(define
+  ev/federated-busy
+  (fn
+    (local-db peers trust actor)
+    (let
+      ((acc (list)))
+      (begin
+        (for-each (fn (iv) (append! acc iv)) (ev-busy local-db actor))
+        (for-each
+          (fn
+            (peer)
+            (when
+              (ev/trusts? trust (ev/peer-id peer))
+              (for-each
+                (fn (iv) (append! acc iv))
+                (ev/peer-busy peer actor))))
+          peers)
+        (ev-sort-lists acc)))))
+
+;; Half-open overlap of interval (s e) with window [qs, qe).
+(define
+  ev-fed-overlaps?
+  (fn (iv qs qe) (and (< (first iv) qe) (< qs (first (rest iv))))))
+
+;; Is `actor` free across [qs, qe) considering local + trusted-peer busy?
+(define
+  ev/federated-free?
+  (fn
+    (local-db peers trust actor qs qe)
+    (not
+      (some
+        (fn (iv) (ev-fed-overlaps? iv qs qe))
+        (ev/federated-busy local-db peers trust actor)))))

lib/events/notify.sx

@@ -0,0 +1,38 @@
+;; lib/events/notify.sx — durable notification delivery flows over an injected
+;; transport (lib/flow).
+;;
+;; Reminders and digests are durable `flow`s: a flow `request`s delivery (a
+;; suspend point), the HOST performs the actual send via an injected `dispatch`
+;; (the transport — email/push/etc.), and resumes the flow with the outcome.
+;; Because flow uses deterministic replay, a completed delivery is never re-run
+;; on recovery; the host owns IO and persistence.
+;;
+;; Delivery is AT-LEAST-ONCE with idempotency. Each message carries an id (the
+;; idempotency key). Two protections stop double-delivery:
+;;   1. The transport dedups by id — a re-send of a delivered id is a no-op
+;;      that still reports ok, so a retry never produces two pings.
+;;   2. flow's replay log records each resolved request, so recovery replays the
+;;      logged outcome instead of re-issuing the send.
+;;
+;; Retry/backoff rides flow suspend/resume: each attempt issues a request with a
+;; DISTINCT tag `(deliver <id> <n>)` — distinct tags keep deterministic replay
+;; correct across retries. The dispatch returns (ok info) to finish or
+;; (retry reason) to try again, bounded by `maxn` (then (failed id reason)).
+;;
+;; A message is a 3-element list (id recipient body). The transport is generic
+;; and injected — when feed/notify lands, both consumers share one transport,
+;; so this delivery core is a candidate for extraction to `delivery-on-sx`.
+;;
+;; The Scheme flow source below loads into a flow env (see lib/flow/api.sx).
+;; `ev/notify-run` prepends it to a caller program and evaluates in the shared
+;; flow env.
+
+(define
+  ev-notify-flows-src
+  "(define (ev-msg-id m) (car m))\n   (define (ev-msg-recipient m) (car (cdr m)))\n   (define (ev-msg-body m) (car (cdr (cdr m))))\n   (define (ev-mem x xs)\n     (if (null? xs) #f (if (equal? x (car xs)) #t (ev-mem x (cdr xs)))))\n   (define (ev-notify-attempt m n maxn)\n     (let ((r (request (list (quote deliver) (ev-msg-id m) n) m)))\n       (if (eq? (car r) (quote ok))\n           (list (quote delivered) (ev-msg-id m) n)\n           (if (>= n maxn)\n               (list (quote failed) (ev-msg-id m) (car (cdr r)))\n               (ev-notify-attempt m (+ n 1) maxn)))))\n   (define (ev-deliver-reminder maxn)\n     (flow-node (lambda (m) (ev-notify-attempt m 1 maxn))))\n   (define (ev-digest-step ms maxn)\n     (if (null? ms)\n         (list)\n         (cons (ev-notify-attempt (car ms) 1 maxn)\n               (ev-digest-step (cdr ms) maxn))))\n   (define (ev-deliver-digest maxn)\n     (flow-node (lambda (ms) (ev-digest-step ms maxn))))")
+
+;; Run a Scheme flow program with the notify flows preloaded, in the shared
+;; flow env. Returns the program's value (SX-native).
+(define
+  ev/notify-run
+  (fn (prog) (flow-run (str ev-notify-flows-src "\n" prog))))

lib/events/reminders.sx

@@ -0,0 +1,147 @@
+;; lib/events/reminders.sx — derive reminder + digest messages from the agenda.
+;;
+;; Bridges the schedule (calendar) and the durable roster (booking on persist)
+;; to the notification layer (notify.sx). For each booked attendee of each
+;; upcoming occurrence we derive a reminder message that fires `lead` minutes
+;; before the occurrence starts. Each message has a deterministic idempotency
+;; key — occ-key / recipient / lead — so re-deriving over an overlapping window
+;; never produces a duplicate ping (the notify transport dedups on this id).
+;;
+;; A reminder is a dict:
+;;   {:id :recipient :event :start :fire-at}
+;; `ev/reminder->msg` projects it to notify's (id recipient body) wire shape.
+
+;; Reminders for one occurrence: one per booked attendee (durable roster).
+(define
+  ev/occurrence-reminders
+  (fn
+    (b occ lead)
+    (let
+      ((occ-key (ev-occ-key occ))
+        (start (get occ :start))
+        (evid (get occ :id)))
+      (map (fn (actor) {:id (str occ-key "/" actor "/" lead) :event evid :start start :fire-at (- start lead) :recipient actor}) (ev/roster-occ b occ)))))
+
+;; Insertion sort of reminder dicts ascending by :fire-at (then :id for ties).
+(define
+  ev-rem-before?
+  (fn
+    (a c)
+    (cond
+      ((< (get a :fire-at) (get c :fire-at)) true)
+      ((> (get a :fire-at) (get c :fire-at)) false)
+      (else (< (get a :id) (get c :id))))))
+
+(define
+  ev-rem-insert
+  (fn
+    (r sorted)
+    (cond
+      ((empty? sorted) (list r))
+      ((ev-rem-before? r (first sorted)) (cons r sorted))
+      (else (cons (first sorted) (ev-rem-insert r (rest sorted)))))))
+
+(define
+  ev-rem-sort
+  (fn (rs) (reduce (fn (acc r) (ev-rem-insert r acc)) (list) rs)))
+
+;; All reminders across the agenda in [ws, we), ascending by fire-at.
+(define
+  ev/agenda-reminders
+  (fn
+    (b store ws we lead)
+    (let
+      ((acc (list)))
+      (begin
+        (for-each
+          (fn
+            (occ)
+            (for-each
+              (fn (r) (append! acc r))
+              (ev/occurrence-reminders b occ lead)))
+          (ev/agenda store ws we))
+        (ev-rem-sort acc)))))
+
+;; Reminders whose fire-at has arrived (fire-at <= now) — what a scheduler
+;; should hand to the notify transport at time `now`.
+(define
+  ev/due-reminders
+  (fn
+    (reminders now)
+    (filter (fn (r) (<= (get r :fire-at) now)) reminders)))
+
+;; Project a reminder to notify's (id recipient body) wire shape.
+(define
+  ev/reminder->msg
+  (fn
+    (r)
+    (list
+      (get r :id)
+      (get r :recipient)
+      (list :reminder (get r :event) (get r :start)))))
+
+;; ---- digests ----
+
+;; The occurrences `actor` is booked into (durable roster), within window.
+(define
+  ev/agenda-for-p
+  (fn
+    (b store actor ws we)
+    (filter
+      (fn (occ) (ev-bk-member? actor (ev/roster-occ b occ)))
+      (ev/agenda store ws we))))
+
+;; A single digest message summarising an actor's upcoming booked occurrences.
+;; :items is ({:event :start} ...); empty when the actor has nothing booked.
+(define ev/agenda-digest (fn (b store actor ws we) {:items (map (fn (occ) {:event (get occ :id) :start (get occ :start)}) (ev/agenda-for-p b store actor ws we)) :id (str actor "/digest/" ws "-" we) :recipient actor}))
+
+;; ---- reschedule notifications ----
+;; When an event carries per-occurrence overrides (ev-with-override), every
+;; attendee booked at the ORIGINAL start should be told the new time. Bookings
+;; were made against the original occ-key (id@orig-start), so we read that
+;; roster. Idempotency key encodes the original key and the new start, so
+;; re-deriving the same reschedule never double-notifies.
+(define
+  ev/reschedule-notifications
+  (fn
+    (b event)
+    (let
+      ((overrides (ev-or (get event :overrides) (list)))
+        (evid (get event :id))
+        (dur (get event :duration)))
+      (reduce
+        (fn
+          (acc entry)
+          (let
+            ((orig-start (first entry))
+              (ov (first (rest entry))))
+            (let
+              ((occ (ev-occ evid orig-start dur))
+                (new-start (get ov :start))
+                (new-duration (get ov :duration)))
+              (let
+                ((key (ev-occ-key occ)))
+                (append
+                  acc
+                  (map
+                    (fn
+                      (actor)
+                      {:id (str key "/reschedule/" new-start)
+                        :recipient actor
+                        :event evid
+                        :old-start orig-start
+                        :new-start new-start
+                        :new-duration new-duration})
+                    (ev/roster-occ b occ)))))))
+        (list)
+        overrides))))
+
+;; Project a reschedule notification to notify's (id recipient body) shape.
+(define
+  ev/reschedule-notify->msg
+  (fn
+    (r)
+    (list
+      (get r :id)
+      (get r :recipient)
+      (list :rescheduled (get r :event) (get r :old-start) (get r :new-start)))))

lib/events/scoreboard.json

@@ -0,0 +1,18 @@
+{
+  "lang": "events",
+  "total_passed": 272,
+  "total_failed": 0,
+  "total": 272,
+  "suites": [
+    {"name":"calendar","passed":51,"failed":0,"total":51},
+    {"name":"availability","passed":22,"failed":0,"total":22},
+    {"name":"api","passed":24,"failed":0,"total":24},
+    {"name":"booking","passed":82,"failed":0,"total":82},
+    {"name":"booking-notify","passed":11,"failed":0,"total":11},
+    {"name":"ticket","passed":31,"failed":0,"total":31},
+    {"name":"notify","passed":7,"failed":0,"total":7},
+    {"name":"reminders","passed":21,"failed":0,"total":21},
+    {"name":"federation","passed":23,"failed":0,"total":23}
+  ],
+  "generated": "2026-06-07T07:46:42+00:00"
+}

lib/events/scoreboard.md

@@ -0,0 +1,15 @@
+# events scoreboard
+
+**272 / 272 passing** (0 failure(s)).
+
+| Suite | Passed | Total | Status |
+|-------|--------|-------|--------|
+| calendar | 51 | 51 | ok |
+| availability | 22 | 22 | ok |
+| api | 24 | 24 | ok |
+| booking | 82 | 82 | ok |
+| booking-notify | 11 | 11 | ok |
+| ticket | 31 | 31 | ok |
+| notify | 7 | 7 | ok |
+| reminders | 21 | 21 | ok |
+| federation | 23 | 23 | ok |

lib/events/tests/api.sx

@@ -0,0 +1,271 @@
+;; lib/events/tests/api.sx — public events facade (schedule/agenda/free/book).
+
+(define ev-api-pass 0)
+(define ev-api-fail 0)
+(define ev-api-failures (list))
+
+(define
+  ev-api-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-api-pass (+ ev-api-pass 1))
+      (do
+        (set! ev-api-fail (+ ev-api-fail 1))
+        (append!
+          ev-api-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; A store with a weekly yoga class (Mon+Wed 18:00, 60m, 4 occurrences).
+(define
+  ev-api-store
+  (fn
+    ()
+    (ev/schedule
+      (ev/empty)
+      (quote yoga)
+      (ev-dt 2026 6 1 18 0)
+      60
+      {:freq :weekly :count 4 :byday (list 0 2)}
+      20)))
+
+(define
+  ev-api-run-all!
+  (fn
+    ()
+    (let
+      ((s0 (ev-api-store)))
+      (let
+        ((occs (ev/agenda s0 (ev-date 2026 6 1) (ev-date 2026 7 1))))
+        (let
+          ((s1 (ev/book (ev/book s0 (quote nia) (ev-occ-key (first occs))) (quote nia) (ev-occ-key (first (rest occs))))))
+          (do
+            (ev-api-check!
+              "agenda expands weekly class to four occurrences"
+              (map (fn (o) (ev-dt->civil (get o :start))) occs)
+              (list
+                (list 2026 6 1)
+                (list 2026 6 3)
+                (list 2026 6 8)
+                (list 2026 6 10)))
+            (ev-api-check!
+              "empty store has empty agenda"
+              (ev/agenda
+                (ev/empty)
+                (ev-date 2026 6 1)
+                (ev-date 2026 7 1))
+              (list))
+            (ev-api-check!
+              "max duration reflects scheduled events"
+              (ev/store-max-duration s0)
+              60)
+            (ev-api-check!
+              "max duration of empty store is zero"
+              (ev/store-max-duration (ev/empty))
+              0)
+            (ev-api-check!
+              "event-by-id finds the scheduled event"
+              (get (ev/event-by-id s0 (quote yoga)) :capacity)
+              20)
+            (ev-api-check!
+              "event-by-id is nil for unknown id"
+              (ev/event-by-id s0 (quote nope))
+              nil)
+            (ev-api-check!
+              "agenda-for lists only booked occurrences"
+              (map
+                (fn (o) (ev-dt->civil (get o :start)))
+                (ev/agenda-for
+                  s1
+                  (quote nia)
+                  (ev-date 2026 6 1)
+                  (ev-date 2026 7 1)))
+              (list
+                (list 2026 6 1)
+                (list 2026 6 3)))
+            (ev-api-check!
+              "agenda-for empty for unbooked actor"
+              (ev/agenda-for
+                s1
+                (quote zed)
+                (ev-date 2026 6 1)
+                (ev-date 2026 7 1))
+              (list))
+            (ev-api-check!
+              "free? false during a booked occurrence"
+              (ev/free?
+                s1
+                (quote nia)
+                (ev-dt 2026 6 1 18 30)
+                (ev-dt 2026 6 1 19 0))
+              false)
+            (ev-api-check!
+              "free? true in an open window"
+              (ev/free?
+                s1
+                (quote nia)
+                (ev-dt 2026 6 1 9 0)
+                (ev-dt 2026 6 1 10 0))
+              true)
+            (ev-api-check!
+              "free? half-open at occurrence end"
+              (ev/free?
+                s1
+                (quote nia)
+                (ev-dt 2026 6 1 19 0)
+                (ev-dt 2026 6 1 20 0))
+              true)
+            (ev-api-check!
+              "free? true for an actor who booked nothing"
+              (ev/free?
+                s1
+                (quote zed)
+                (ev-dt 2026 6 1 18 0)
+                (ev-dt 2026 6 1 19 0))
+              true)
+            (ev-api-check!
+              "next-free skips the booked slot to the hour after"
+              (ev-dt-tod
+                (ev/next-free
+                  s1
+                  (quote nia)
+                  (ev-dt
+                    2026
+                    6
+                    1
+                    18
+                    0)
+                  60
+                  (ev-dt
+                    2026
+                    6
+                    1
+                    23
+                    0)))
+              (* 19 60))
+            (ev-api-check!
+              "next-free returns `after` when already open"
+              (ev/next-free
+                s1
+                (quote nia)
+                (ev-dt 2026 6 1 9 0)
+                60
+                (ev-dt 2026 6 1 18 0))
+              (ev-dt 2026 6 1 9 0))
+            (ev-api-check!
+              "no conflict among disjoint bookings"
+              (ev/has-conflict?
+                s1
+                (quote nia)
+                (ev-date 2026 6 1)
+                (ev-date 2026 7 1))
+              false)
+            (let
+              ((sc (ev/book (ev/schedule s1 (quote talk) (ev-dt 2026 6 1 18 30) 60 nil 5) (quote nia) (ev-occ-key (ev-occ (quote talk) (ev-dt 2026 6 1 18 30) 60)))))
+              (ev-api-check!
+                "overlapping second booking creates a conflict"
+                (ev/has-conflict?
+                  sc
+                  (quote nia)
+                  (ev-date 2026 6 1)
+                  (ev-date 2026 7 1))
+                true))
+            (let
+              ((b (persist/open)) (occ1 (first occs)))
+              (do
+                (let
+                  ((sp (ev/schedule (ev/empty) (quote clinic) (ev-dt 2026 6 5 9 0) 30 nil 2)))
+                  (let
+                    ((occ (ev-occ (quote clinic) (ev-dt 2026 6 5 9 0) 30)))
+                    (do
+                      (ev-api-check!
+                        "durable book returns booked"
+                        (get (ev/book-occ! b sp (quote a) occ) :status)
+                        :booked)
+                      (ev/book-occ! b sp (quote c) occ)
+                      (ev-api-check!
+                        "durable book past capacity is full"
+                        (get (ev/book-occ! b sp (quote d) occ) :status)
+                        :full)
+                      (ev-api-check!
+                        "durable roster reflects persisted bookings"
+                        (ev/roster-occ b occ)
+                        (list (quote a) (quote c)))
+                      (ev-api-check!
+                        "durable seats-left honours capacity"
+                        (ev/seats-left-occ b sp occ)
+                        0)
+                      (ev-api-check!
+                        "persist free? false during a durable booking"
+                        (ev/free-p?
+                          b
+                          sp
+                          (quote a)
+                          (ev-dt
+                            2026
+                            6
+                            5
+                            9
+                            10)
+                          (ev-dt
+                            2026
+                            6
+                            5
+                            9
+                            20))
+                        false)
+                      (ev-api-check!
+                        "persist free? true in an open window"
+                        (ev/free-p?
+                          b
+                          sp
+                          (quote a)
+                          (ev-dt
+                            2026
+                            6
+                            5
+                            10
+                            0)
+                          (ev-dt
+                            2026
+                            6
+                            5
+                            10
+                            30))
+                        true)
+                      (ev/cancel-occ! b sp (quote a) occ)
+                      (ev-api-check!
+                        "durable cancel frees a seat"
+                        (ev/seats-left-occ b sp occ)
+                        1)
+                      (ev-api-check!
+                        "persist free? true after cancellation"
+                        (ev/free-p?
+                          b
+                          sp
+                          (quote a)
+                          (ev-dt
+                            2026
+                            6
+                            5
+                            9
+                            10)
+                          (ev-dt
+                            2026
+                            6
+                            5
+                            9
+                            20))
+                        true))))))))))))
+
+(define
+  ev-api-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-api-pass 0)
+      (set! ev-api-fail 0)
+      (set! ev-api-failures (list))
+      (ev-api-run-all!)
+      {:failures ev-api-failures :total (+ ev-api-pass ev-api-fail) :passed ev-api-pass :failed ev-api-fail})))

lib/events/tests/availability.sx

@@ -0,0 +1,331 @@
+;; lib/events/tests/availability.sx — free/busy + conflict rules on Datalog.
+
+(define ev-av-pass 0)
+(define ev-av-fail 0)
+(define ev-av-failures (list))
+
+(define
+  ev-av-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-av-pass (+ ev-av-pass 1))
+      (do
+        (set! ev-av-fail (+ ev-av-fail 1))
+        (append!
+          ev-av-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; Fixture: three occurrences on 2026-06-01.
+;;   standup  09:00–09:30   review 09:15–10:15 (overlaps standup)
+;;   lunch    12:00–13:00
+(define
+  ev-av-occs
+  (fn
+    ()
+    (list
+      (ev-occ
+        (quote standup)
+        (ev-dt 2026 6 1 9 0)
+        30)
+      (ev-occ
+        (quote review)
+        (ev-dt 2026 6 1 9 15)
+        60)
+      (ev-occ
+        (quote lunch)
+        (ev-dt 2026 6 1 12 0)
+        60))))
+
+(define ev-av-key (fn (id start) (str id "@" start)))
+
+;; alice: standup + review (overlap → conflict). bob: lunch only.
+(define
+  ev-av-db
+  (fn
+    ()
+    (ev-avail-db
+      (ev-av-occs)
+      (list
+        (list
+          (quote alice)
+          (ev-av-key
+            (quote standup)
+            (ev-dt 2026 6 1 9 0)))
+        (list
+          (quote alice)
+          (ev-av-key
+            (quote review)
+            (ev-dt 2026 6 1 9 15)))
+        (list
+          (quote bob)
+          (ev-av-key
+            (quote lunch)
+            (ev-dt 2026 6 1 12 0)))))))
+
+;; Disjoint fixture for slot search: 09:00–10:00 then 10:30–11:30 (a 30m gap).
+(define
+  ev-av-gap-db
+  (fn
+    ()
+    (ev-avail-db
+      (list
+        (ev-occ
+          (quote a)
+          (ev-dt 2026 6 1 9 0)
+          60)
+        (ev-occ
+          (quote b)
+          (ev-dt 2026 6 1 10 30)
+          60))
+      (list
+        (list
+          (quote sam)
+          (ev-av-key
+            (quote a)
+            (ev-dt 2026 6 1 9 0)))
+        (list
+          (quote sam)
+          (ev-av-key
+            (quote b)
+            (ev-dt 2026 6 1 10 30)))))))
+
+(define
+  ev-av-run-all!
+  (fn
+    ()
+    (let
+      ((db (ev-av-db)))
+      (do
+        (ev-av-check!
+          "busy lists alice committed intervals ascending"
+          (ev-busy db (quote alice))
+          (list
+            (list
+              (ev-dt 2026 6 1 9 0)
+              (ev-dt 2026 6 1 9 30))
+            (list
+              (ev-dt 2026 6 1 9 15)
+              (ev-dt 2026 6 1 10 15))))
+        (ev-av-check!
+          "busy lists bob single interval"
+          (ev-busy db (quote bob))
+          (list
+            (list
+              (ev-dt 2026 6 1 12 0)
+              (ev-dt 2026 6 1 13 0))))
+        (ev-av-check!
+          "busy empty for unknown actor"
+          (ev-busy db (quote carol))
+          (list))
+        (ev-av-check!
+          "alice has an overlap conflict"
+          (ev-has-conflict? db (quote alice))
+          true)
+        (ev-av-check!
+          "alice conflict reported once (canonical pair)"
+          (len (ev-conflicts db (quote alice)))
+          1)
+        (ev-av-check!
+          "bob has no conflict"
+          (ev-has-conflict? db (quote bob))
+          false)
+        (ev-av-check!
+          "non-overlapping bookings do not conflict"
+          (ev-has-conflict?
+            (ev-avail-db
+              (list
+                (ev-occ
+                  (quote a)
+                  (ev-dt
+                    2026
+                    6
+                    1
+                    9
+                    0)
+                  30)
+                (ev-occ
+                  (quote b)
+                  (ev-dt
+                    2026
+                    6
+                    1
+                    9
+                    30)
+                  30))
+              (list
+                (list
+                  (quote dave)
+                  (ev-av-key
+                    (quote a)
+                    (ev-dt
+                      2026
+                      6
+                      1
+                      9
+                      0)))
+                (list
+                  (quote dave)
+                  (ev-av-key
+                    (quote b)
+                    (ev-dt
+                      2026
+                      6
+                      1
+                      9
+                      30)))))
+            (quote dave))
+          false)
+        (ev-av-check!
+          "alice free in an empty window"
+          (ev-free?
+            db
+            (quote alice)
+            (ev-dt 2026 6 1 13 0)
+            (ev-dt 2026 6 1 14 0))
+          true)
+        (ev-av-check!
+          "alice not free overlapping a booking"
+          (ev-free?
+            db
+            (quote alice)
+            (ev-dt 2026 6 1 9 20)
+            (ev-dt 2026 6 1 9 40))
+          false)
+        (ev-av-check!
+          "free? is half-open at the trailing edge"
+          (ev-free?
+            db
+            (quote alice)
+            (ev-dt 2026 6 1 10 15)
+            (ev-dt 2026 6 1 11 0))
+          true)
+        (ev-av-check!
+          "free? is half-open at the leading edge"
+          (ev-free?
+            db
+            (quote bob)
+            (ev-dt 2026 6 1 11 0)
+            (ev-dt 2026 6 1 12 0))
+          true)
+        (ev-av-check!
+          "free? false when window straddles a booking edge"
+          (ev-free?
+            db
+            (quote bob)
+            (ev-dt 2026 6 1 11 0)
+            (ev-dt 2026 6 1 12 1))
+          false)
+        (ev-av-check!
+          "free? query leaves db reusable (no leaked qwindow)"
+          (do
+            (ev-free?
+              db
+              (quote alice)
+              (ev-dt 2026 6 1 9 0)
+              (ev-dt 2026 6 1 9 30))
+            (ev-busy db (quote bob)))
+          (list
+            (list
+              (ev-dt 2026 6 1 12 0)
+              (ev-dt 2026 6 1 13 0))))
+        (let
+          ((gdb (ev-av-gap-db)))
+          (do
+            (ev-av-check!
+              "next-free finds the gap between bookings"
+              (ev-next-free
+                gdb
+                (quote sam)
+                (ev-dt 2026 6 1 9 0)
+                30
+                (ev-dt 2026 6 1 18 0))
+              (ev-dt 2026 6 1 10 0))
+            (ev-av-check!
+              "next-free skips a gap too short for the duration"
+              (ev-next-free
+                gdb
+                (quote sam)
+                (ev-dt 2026 6 1 9 0)
+                60
+                (ev-dt 2026 6 1 18 0))
+              (ev-dt 2026 6 1 11 30))
+            (ev-av-check!
+              "next-free returns `after` when already free"
+              (ev-next-free
+                gdb
+                (quote sam)
+                (ev-dt 2026 6 1 14 0)
+                60
+                (ev-dt 2026 6 1 18 0))
+              (ev-dt 2026 6 1 14 0))
+            (ev-av-check!
+              "next-free returns nil when nothing fits before horizon"
+              (ev-next-free
+                gdb
+                (quote sam)
+                (ev-dt 2026 6 1 9 0)
+                120
+                (ev-dt 2026 6 1 11 0))
+              nil)
+            (ev-av-check!
+              "next-free for actor with no bookings is `after`"
+              (ev-next-free
+                gdb
+                (quote nobody)
+                (ev-dt 2026 6 1 9 0)
+                60
+                (ev-dt 2026 6 1 18 0))
+              (ev-dt 2026 6 1 9 0))
+            (ev-av-check!
+              "next-free at exact edge of a booking (half-open)"
+              (ev-next-free
+                gdb
+                (quote sam)
+                (ev-dt 2026 6 1 10 0)
+                30
+                (ev-dt 2026 6 1 18 0))
+              (ev-dt 2026 6 1 10 0))))
+        (let
+          ((daily (ev-expand (ev-event (quote class) (ev-dt 2026 6 1 9 0) 60 {:freq :daily :count 3} 1) (ev-date 2026 6 1) (ev-date 2026 7 1))))
+          (let
+            ((db2 (ev-avail-db daily (map (fn (o) (list (quote sam) (ev-occ-key o))) daily))))
+            (do
+              (ev-av-check!
+                "expanded daily occurrences become busy intervals"
+                (len (ev-busy db2 (quote sam)))
+                3)
+              (ev-av-check!
+                "no conflicts among disjoint daily occurrences"
+                (ev-has-conflict? db2 (quote sam))
+                false)
+              (ev-av-check!
+                "busy on day two of the series"
+                (ev-free?
+                  db2
+                  (quote sam)
+                  (ev-dt
+                    2026
+                    6
+                    2
+                    9
+                    30)
+                  (ev-dt
+                    2026
+                    6
+                    2
+                    9
+                    45))
+                false))))))))
+
+(define
+  ev-availability-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-av-pass 0)
+      (set! ev-av-fail 0)
+      (set! ev-av-failures (list))
+      (ev-av-run-all!)
+      {:failures ev-av-failures :total (+ ev-av-pass ev-av-fail) :passed ev-av-pass :failed ev-av-fail})))

lib/events/tests/booking-notify.sx

@@ -0,0 +1,137 @@
+;; lib/events/tests/booking-notify.sx — lifecycle notifications from the stream.
+
+(define ev-bn-pass 0)
+(define ev-bn-fail 0)
+(define ev-bn-failures (list))
+
+(define
+  ev-bn-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-bn-pass (+ ev-bn-pass 1))
+      (do
+        (set! ev-bn-fail (+ ev-bn-fail 1))
+        (append!
+          ev-bn-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+(define
+  ev-bn-kinds
+  (fn
+    (notifs)
+    (map (fn (n) (list (get n :recipient) (get n :kind))) notifs)))
+
+(define
+  ev-bn-run-all!
+  (fn
+    ()
+    (do
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "o" 1 (quote a))
+          (ev/waitlist! b "o" 1 (quote x))
+          (ev/cancel-promote! b "o" 1 (quote a))
+          (let
+            ((ns (ev/booking-notifications b "o" (quote yoga))))
+            (do
+              (ev-bn-check!
+                "lifecycle notifications in order"
+                (ev-bn-kinds ns)
+                (list
+                  (list (quote a) :booked)
+                  (list (quote x) :waitlisted)
+                  (list (quote a) :cancelled)
+                  (list (quote x) :promoted)))
+              (ev-bn-check!
+                "promotion targets the waitlisted actor"
+                (map
+                  (fn (n) (get n :recipient))
+                  (ev/notify-of-kind ns :promoted))
+                (list (quote x)))
+              (ev-bn-check!
+                "a fresh booking is not flagged as a promotion"
+                (len (ev/notify-of-kind ns :booked))
+                1)
+              (ev-bn-check!
+                "every notification carries the event label"
+                (get (first ns) :event)
+                (quote yoga))))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/hold! b "p" 3 (quote q))
+          (ev/confirm! b "p" (quote q))
+          (ev-bn-check!
+            "hold then confirm notifications"
+            (ev-bn-kinds (ev/booking-notifications b "p" (quote gig)))
+            (list (list (quote q) :held) (list (quote q) :confirmed)))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/hold! b "r" 1 (quote q))
+          (ev/release! b "r" (quote q))
+          (ev-bn-check!
+            "hold then release notifications"
+            (ev-bn-kinds (ev/booking-notifications b "r" (quote gig)))
+            (list (list (quote q) :held) (list (quote q) :released)))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "k" 5 (quote a))
+          (ev/book! b "k" 5 (quote c))
+          (let
+            ((ns (ev/booking-notifications b "k" (quote talk))))
+            (do
+              (ev-bn-check!
+                "notification ids are occ-key/seq"
+                (map (fn (n) (get n :id)) ns)
+                (list "k/1" "k/2"))
+              (ev-bn-check!
+                "re-deriving yields identical ids (idempotent)"
+                (map
+                  (fn (n) (get n :id))
+                  (ev/booking-notifications b "k" (quote talk)))
+                (list "k/1" "k/2"))))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "w" 5 (quote a))
+          (ev-bn-check!
+            "notification projects to (id recipient body)"
+            (ev/booking-notify->msg
+              (first (ev/booking-notifications b "w" (quote talk))))
+            (list
+              "w/1"
+              (quote a)
+              (list :booking-event :booked (quote talk))))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "u" 1 (quote a))
+          (ev/waitlist! b "u" 1 (quote x))
+          (ev/leave-waitlist! b "u" (quote x))
+          (ev-bn-check!
+            "leaving the waitlist emits no notification"
+            (len
+              (ev/notify-of-kind
+                (ev/booking-notifications b "u" (quote e))
+                :left-waitlist))
+            0)
+          (ev-bn-check!
+            "unbooked occurrence has no notifications"
+            (ev/booking-notifications b "empty" (quote e))
+            (list)))))))
+
+(define
+  ev-booking-notify-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-bn-pass 0)
+      (set! ev-bn-fail 0)
+      (set! ev-bn-failures (list))
+      (ev-bn-run-all!)
+      {:failures ev-bn-failures :total (+ ev-bn-pass ev-bn-fail) :passed ev-bn-pass :failed ev-bn-fail})))

lib/events/tests/booking.sx

@@ -0,0 +1,431 @@
+;; lib/events/tests/booking.sx — capacity-safe booking, cancel, and holds.
+
+(define ev-bk-pass 0)
+(define ev-bk-fail 0)
+(define ev-bk-failures (list))
+
+(define
+  ev-bk-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-bk-pass (+ ev-bk-pass 1))
+      (do
+        (set! ev-bk-fail (+ ev-bk-fail 1))
+        (append!
+          ev-bk-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; Take a consistent (roster, last-seq) snapshot of an occurrence's stream.
+(define ev-bk-snap (fn (b k) (ev-booked-actors b k)))
+(define ev-bk-seq (fn (b k) (persist/last-seq b (ev-booking-stream k))))
+
+(define
+  ev-bk-run-all!
+  (fn
+    ()
+    (do
+      (let
+        ((b (persist/open)))
+        (do
+          (ev-bk-check!
+            "first booking takes seat 1"
+            (get (ev/book! b "o1" 3 (quote a)) :seat)
+            1)
+          (ev-bk-check!
+            "second booking takes seat 2"
+            (get (ev/book! b "o1" 3 (quote c)) :seat)
+            2)
+          (ev-bk-check!
+            "booked status reported"
+            (get (ev/book! b "o1" 3 (quote d)) :status)
+            :booked)
+          (ev-bk-check!
+            "roster is oldest-first"
+            (ev/roster b "o1")
+            (list (quote a) (quote c) (quote d)))
+          (ev-bk-check!
+            "seats-left is zero when full"
+            (ev/seats-left b "o1" 3)
+            0)
+          (ev-bk-check!
+            "free booking is confirmed state"
+            (ev/seat-state b "o1" (quote a))
+            :confirmed)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "o2" 1 (quote a))
+          (ev-bk-check!
+            "booking past capacity is refused"
+            (get (ev/book! b "o2" 1 (quote c)) :status)
+            :full)
+          (ev-bk-check!
+            "full does not grow the roster"
+            (ev/roster b "o2")
+            (list (quote a)))
+          (ev-bk-check!
+            "seats-left zero at capacity"
+            (ev/seats-left b "o2" 1)
+            0)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "o3" 5 (quote a))
+          (ev-bk-check!
+            "re-booking the same actor is idempotent"
+            (get (ev/book! b "o3" 5 (quote a)) :status)
+            :already)
+          (ev-bk-check!
+            "idempotent re-book reports existing seat"
+            (get (ev/book! b "o3" 5 (quote a)) :seat)
+            1)
+          (ev-bk-check!
+            "roster unchanged after re-book"
+            (ev/roster b "o3")
+            (list (quote a)))
+          (ev-bk-check!
+            "count unchanged after re-book"
+            (ev-booking-count b "o3")
+            1)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "last" 2 (quote x))
+          (let
+            ((snap (ev-bk-snap b "last")) (exp (ev-bk-seq b "last")))
+            (let
+              ((ra (ev/book-with-observed b "last" 2 (quote a) snap exp))
+                (rb
+                  (ev/book-with-observed
+                    b
+                    "last"
+                    2
+                    (quote bee)
+                    snap
+                    exp)))
+              (do
+                (ev-bk-check!
+                  "race winner is booked"
+                  (get ra :status)
+                  :booked)
+                (ev-bk-check!
+                  "race winner takes the last seat"
+                  (get ra :seat)
+                  2)
+                (ev-bk-check!
+                  "race loser is rejected with a conflict"
+                  (get rb :status)
+                  :conflict)
+                (ev-bk-check!
+                  "conflict reports the advanced seq"
+                  (get rb :actual)
+                  (+ exp 1))
+                (ev-bk-check!
+                  "no overbooking: exactly two on roster"
+                  (ev-booking-count b "last")
+                  2)
+                (ev-bk-check!
+                  "race loser is NOT on the roster"
+                  (ev-bk-member? (quote bee) (ev/roster b "last"))
+                  false)
+                (ev-bk-check!
+                  "race loser retrying gets full"
+                  (get (ev/book! b "last" 2 (quote bee)) :status)
+                  :full))))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "room" 3 (quote x))
+          (let
+            ((snap (ev-bk-snap b "room")) (exp (ev-bk-seq b "room")))
+            (let
+              ((ra (ev/book-with-observed b "room" 3 (quote a) snap exp))
+                (rb
+                  (ev/book-with-observed
+                    b
+                    "room"
+                    3
+                    (quote bee)
+                    snap
+                    exp)))
+              (do
+                (ev-bk-check!
+                  "room winner booked seat 2"
+                  (get ra :seat)
+                  2)
+                (ev-bk-check!
+                  "room loser first conflicts"
+                  (get rb :status)
+                  :conflict)
+                (ev-bk-check!
+                  "room loser retry books seat 3"
+                  (get (ev/book! b "room" 3 (quote bee)) :seat)
+                  3)
+                (ev-bk-check!
+                  "room roster is x,a,bee"
+                  (ev/roster b "room")
+                  (list (quote x) (quote a) (quote bee)))
+                (ev-bk-check!
+                  "room is now full"
+                  (ev/seats-left b "room" 3)
+                  0))))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "cx" 2 (quote a))
+          (ev/book! b "cx" 2 (quote c))
+          (ev-bk-check!
+            "occupied to capacity before cancel"
+            (ev/seats-left b "cx" 2)
+            0)
+          (ev-bk-check!
+            "booking when full (pre-cancel) is refused"
+            (get (ev/book! b "cx" 2 (quote d)) :status)
+            :full)
+          (ev-bk-check!
+            "cancel reports cancelled"
+            (get (ev/cancel! b "cx" (quote a)) :status)
+            :cancelled)
+          (ev-bk-check!
+            "cancel removes actor from roster"
+            (ev/roster b "cx")
+            (list (quote c)))
+          (ev-bk-check!
+            "cancel frees a seat"
+            (ev/seats-left b "cx" 2)
+            1)
+          (ev-bk-check!
+            "freed seat is bookable again"
+            (get (ev/book! b "cx" 2 (quote d)) :status)
+            :booked)
+          (ev-bk-check!
+            "roster after rebook is c,d"
+            (ev/roster b "cx")
+            (list (quote c) (quote d)))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "ce" 3 (quote a))
+          (ev-bk-check!
+            "cancelling an unbooked actor is a no-op"
+            (get (ev/cancel! b "ce" (quote z)) :status)
+            :not-booked)
+          (ev-bk-check!
+            "no-op cancel leaves roster intact"
+            (ev/roster b "ce")
+            (list (quote a)))
+          (ev/cancel! b "ce" (quote a))
+          (ev-bk-check!
+            "double cancel is not-booked the second time"
+            (get (ev/cancel! b "ce" (quote a)) :status)
+            :not-booked)
+          (ev-bk-check!
+            "empty roster after cancel"
+            (ev/roster b "ce")
+            (list))
+          (ev-bk-check!
+            "cancelled actor may re-book"
+            (get (ev/book! b "ce" 3 (quote a)) :status)
+            :booked)
+          (ev-bk-check!
+            "re-booked actor back on roster"
+            (ev/roster b "ce")
+            (list (quote a)))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "h" 2 (quote a))
+          (ev-bk-check!
+            "hold reports held"
+            (get (ev/hold! b "h" 2 (quote p)) :status)
+            :held)
+          (ev-bk-check!
+            "held seat is :held state"
+            (ev/seat-state b "h" (quote p))
+            :held)
+          (ev-bk-check!
+            "held actor is on the roster"
+            (ev/roster b "h")
+            (list (quote a) (quote p)))
+          (ev-bk-check!
+            "held seat blocks the last booking"
+            (get (ev/book! b "h" 2 (quote x)) :status)
+            :full)
+          (ev-bk-check!
+            "no seats left with one held"
+            (ev/seats-left b "h" 2)
+            0)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/hold! b "hc" 3 (quote p))
+          (ev-bk-check!
+            "confirm reports confirmed"
+            (get (ev/confirm! b "hc" (quote p)) :status)
+            :confirmed)
+          (ev-bk-check!
+            "confirmed seat is :confirmed state"
+            (ev/seat-state b "hc" (quote p))
+            :confirmed)
+          (ev-bk-check!
+            "re-confirm is already-confirmed"
+            (get (ev/confirm! b "hc" (quote p)) :status)
+            :already-confirmed)
+          (ev-bk-check!
+            "confirming a non-holder is not-held"
+            (get (ev/confirm! b "hc" (quote z)) :status)
+            :not-held)
+          (ev-bk-check!
+            "confirmed seat still occupies"
+            (ev/seats-left b "hc" 3)
+            2)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "hr" 2 (quote a))
+          (ev/hold! b "hr" 2 (quote p))
+          (ev-bk-check!
+            "full while hold pending"
+            (ev/seats-left b "hr" 2)
+            0)
+          (ev-bk-check!
+            "release reports released"
+            (get (ev/release! b "hr" (quote p)) :status)
+            :released)
+          (ev-bk-check!
+            "release frees the held seat"
+            (ev/seats-left b "hr" 2)
+            1)
+          (ev-bk-check!
+            "released actor off the roster"
+            (ev/roster b "hr")
+            (list (quote a)))
+          (ev-bk-check!
+            "freed seat bookable after release"
+            (get (ev/book! b "hr" 2 (quote x)) :status)
+            :booked)
+          (ev/hold! b "hr2" 1 (quote q))
+          (ev/confirm! b "hr2" (quote q))
+          (ev-bk-check!
+            "release on a confirmed seat is not-held"
+            (get (ev/release! b "hr2" (quote q)) :status)
+            :not-held)
+          (ev-bk-check!
+            "cancel frees a confirmed-from-hold seat"
+            (get (ev/cancel! b "hr2" (quote q)) :status)
+            :cancelled)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/book! b "hlast" 2 (quote x))
+          (let
+            ((snap (ev-bk-snap b "hlast")) (exp (ev-bk-seq b "hlast")))
+            (let
+              ((ra (ev/hold-with-observed b "hlast" 2 (quote p) snap exp))
+                (rb
+                  (ev/hold-with-observed
+                    b
+                    "hlast"
+                    2
+                    (quote q)
+                    snap
+                    exp)))
+              (do
+                (ev-bk-check! "hold race winner held" (get ra :status) :held)
+                (ev-bk-check!
+                  "hold race loser conflicts"
+                  (get rb :status)
+                  :conflict)
+                (ev-bk-check!
+                  "no oversell via concurrent holds"
+                  (ev-booking-count b "hlast")
+                  2)
+                (ev-bk-check!
+                  "hold loser retry gets full"
+                  (get (ev/hold! b "hlast" 2 (quote q)) :status)
+                  :full))))))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/hold! b "hi" 4 (quote p))
+          (ev-bk-check!
+            "re-holding the same actor is idempotent"
+            (get (ev/hold! b "hi" 4 (quote p)) :status)
+            :already)
+          (ev-bk-check!
+            "hold idempotency keeps one seat"
+            (ev-booking-count b "hi")
+            1))))))
+
+;; ---- waitlist ----
+(define
+  ev-bk-wl-run-all!
+  (fn
+    ()
+    (do
+      ;; join the waitlist when full; book directly when a seat is free
+      (let
+        ((b (persist/open)))
+        (do
+          (ev-bk-check! "waitlist! books when a seat is free" (get (ev/waitlist! b "w" 2 (quote a)) :status) :booked)
+          (ev-bk-check! "second booking still fits" (get (ev/waitlist! b "w" 2 (quote c)) :status) :booked)
+          (ev-bk-check! "third joins the waitlist when full" (get (ev/waitlist! b "w" 2 (quote x)) :status) :waitlisted)
+          (ev-bk-check! "fourth is next in line" (get (ev/waitlist! b "w" 2 (quote y)) :position) 2)
+          (ev-bk-check! "waitlist is FIFO" (ev/waitlist b "w") (list (quote x) (quote y)))
+          (ev-bk-check! "seats unaffected by waitlisting" (ev/roster b "w") (list (quote a) (quote c)))
+          (ev-bk-check! "waitlist-position reports a queued actor" (ev/waitlist-position b "w" (quote y)) 2)
+          (ev-bk-check! "waitlist-position 0 for a seated actor" (ev/waitlist-position b "w" (quote a)) 0)))
+      ;; idempotency
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/waitlist! b "wi" 1 (quote a))
+          (ev/waitlist! b "wi" 1 (quote x))
+          (ev-bk-check! "re-joining as a seated actor is :already" (get (ev/waitlist! b "wi" 1 (quote a)) :status) :already)
+          (ev-bk-check! "re-joining the queue is :already-waiting" (get (ev/waitlist! b "wi" 1 (quote x)) :status) :already-waiting)
+          (ev-bk-check! "queue did not grow on re-join" (ev/waitlist b "wi") (list (quote x)))))
+      ;; leaving the waitlist
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/waitlist! b "wl" 1 (quote a))
+          (ev/waitlist! b "wl" 1 (quote x))
+          (ev/waitlist! b "wl" 1 (quote y))
+          (ev-bk-check! "leave-waitlist reports left" (get (ev/leave-waitlist! b "wl" (quote x)) :status) :left)
+          (ev-bk-check! "leaving removes from the queue" (ev/waitlist b "wl") (list (quote y)))
+          (ev-bk-check! "leaving when not queued is not-waiting" (get (ev/leave-waitlist! b "wl" (quote z)) :status) :not-waiting)))
+      ;; auto-promotion on cancel
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/waitlist! b "wp" 1 (quote a))
+          (ev/waitlist! b "wp" 1 (quote x))
+          (ev/waitlist! b "wp" 1 (quote y))
+          (let
+            ((r (ev/cancel-promote! b "wp" 1 (quote a))))
+            (do
+              (ev-bk-check! "cancel-promote cancels the seat holder" (get r :status) :cancelled)
+              (ev-bk-check! "cancel-promote promotes the head of the queue" (get r :promoted) (quote x))))
+          (ev-bk-check! "promoted actor now holds the seat" (ev/roster b "wp") (list (quote x)))
+          (ev-bk-check! "promoted actor left the queue" (ev/waitlist b "wp") (list (quote y)))
+          (ev-bk-check! "promoted seat is confirmed" (ev/seat-state b "wp" (quote x)) :confirmed)
+          ;; cancelling with an empty waitlist promotes nobody
+          (ev/leave-waitlist! b "wp" (quote y))
+          (let
+            ((r2 (ev/cancel-promote! b "wp" 1 (quote x))))
+            (ev-bk-check! "cancel with empty waitlist promotes nobody" (get r2 :promoted) nil))
+          (ev-bk-check! "seat is free after the last cancel" (ev/seats-left b "wp" 1) 1))))))
+
+(define
+  ev-booking-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-bk-pass 0)
+      (set! ev-bk-fail 0)
+      (set! ev-bk-failures (list))
+      (ev-bk-run-all!)
+      (ev-bk-wl-run-all!)
+      {:failures ev-bk-failures :total (+ ev-bk-pass ev-bk-fail) :passed ev-bk-pass :failed ev-bk-fail})))

lib/events/tests/calendar.sx

@@ -0,0 +1,592 @@
+;; lib/events/tests/calendar.sx — civil date core + RRULE window expansion.
+
+(define ev-cal-pass 0)
+(define ev-cal-fail 0)
+(define ev-cal-failures (list))
+
+(define
+  ev-cal-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-cal-pass (+ ev-cal-pass 1))
+      (do
+        (set! ev-cal-fail (+ ev-cal-fail 1))
+        (append!
+          ev-cal-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; Project occurrences to (civil weekday) pairs for legible assertions.
+(define
+  ev-cal-shape
+  (fn
+    (occs)
+    (map
+      (fn
+        (o)
+        (list (ev-dt->civil (get o :start)) (ev-dt-weekday (get o :start))))
+      occs)))
+
+(define
+  ev-cal-starts
+  (fn (occs) (map (fn (o) (ev-dt->civil (get o :start))) occs)))
+
+(define
+  ev-cal-run-all!
+  (fn
+    ()
+    (do
+      (ev-cal-check!
+        "epoch day zero"
+        (ev-days-from-civil 1970 1 1)
+        0)
+      (ev-cal-check!
+        "y2k day number"
+        (ev-days-from-civil 2000 1 1)
+        10957)
+      (ev-cal-check!
+        "leap day round trip"
+        (ev-civil-from-days
+          (ev-days-from-civil 2024 2 29))
+        (list 2024 2 29))
+      (ev-cal-check!
+        "pre-epoch round trip"
+        (ev-civil-from-days
+          (ev-days-from-civil 1969 12 31))
+        (list 1969 12 31))
+      (ev-cal-check!
+        "epoch is thursday"
+        (ev-weekday-of-days 0)
+        3)
+      (ev-cal-check!
+        "2026-06-06 is saturday"
+        (ev-dt-weekday (ev-date 2026 6 6))
+        5)
+      (ev-cal-check!
+        "dt carries time of day"
+        (ev-dt-tod
+          (ev-dt 2026 6 1 9 30))
+        570)
+      (ev-cal-check!
+        "civil from dt"
+        (ev-dt->civil
+          (ev-dt 2026 12 25 8 0))
+        (list 2026 12 25))
+      (ev-cal-check!
+        "days in feb 2024 (leap)"
+        (ev-days-in-month 2024 2)
+        29)
+      (ev-cal-check!
+        "days in feb 2026"
+        (ev-days-in-month 2026 2)
+        28)
+      (ev-cal-check!
+        "add months wraps year"
+        (ev-add-months 2026 11 3)
+        (list 2027 2))
+      (ev-cal-check!
+        "add months within year"
+        (ev-add-months 2026 1 5)
+        (list 2026 6))
+      (let
+        ((ev (ev-event (quote one) (ev-dt 2026 6 10 14 0) 60 nil 1)))
+        (do
+          (ev-cal-check!
+            "single inside window emits once"
+            (len
+              (ev-expand
+                ev
+                (ev-date 2026 6 1)
+                (ev-date 2026 7 1)))
+            1)
+          (ev-cal-check!
+            "single before window omitted"
+            (len
+              (ev-expand
+                ev
+                (ev-date 2026 7 1)
+                (ev-date 2026 8 1)))
+            0)
+          (ev-cal-check!
+            "single after window omitted"
+            (len
+              (ev-expand
+                ev
+                (ev-date 2026 1 1)
+                (ev-date 2026 2 1)))
+            0)
+          (ev-cal-check!
+            "occurrence end is start plus duration"
+            (get
+              (first
+                (ev-expand
+                  ev
+                  (ev-date 2026 6 1)
+                  (ev-date 2026 7 1)))
+              :end)
+            (+
+              (ev-dt 2026 6 10 14 0)
+              60))))
+      (let
+        ((daily (ev-event (quote d) (ev-dt 2026 6 1 9 0) 30 {:freq :daily :count 5} 1)))
+        (do
+          (ev-cal-check!
+            "daily count caps occurrences"
+            (ev-cal-starts
+              (ev-expand
+                daily
+                (ev-date 2026 6 1)
+                (ev-date 2026 7 1)))
+            (list
+              (list 2026 6 1)
+              (list 2026 6 2)
+              (list 2026 6 3)
+              (list 2026 6 4)
+              (list 2026 6 5)))
+          (ev-cal-check!
+            "daily preserves time of day"
+            (ev-dt-tod
+              (get
+                (first
+                  (ev-expand
+                    daily
+                    (ev-date 2026 6 1)
+                    (ev-date 2026 7 1)))
+                :start))
+            540)))
+      (let
+        ((di (ev-event (quote di) (ev-dt 2026 6 1 0 0) 30 {:interval 3 :freq :daily :until (ev-date 2026 6 30)} 1)))
+        (ev-cal-check!
+          "daily interval 3 steps by three days"
+          (ev-cal-starts
+            (ev-expand
+              di
+              (ev-date 2026 6 1)
+              (ev-date 2026 6 13)))
+          (list
+            (list 2026 6 1)
+            (list 2026 6 4)
+            (list 2026 6 7)
+            (list 2026 6 10)
+            (list 2026 6 13))))
+      (let
+        ((dc (ev-event (quote dc) (ev-dt 2026 6 1 0 0) 30 {:freq :daily :count 10} 1)))
+        (ev-cal-check!
+          "count is window-independent (clip middle)"
+          (ev-cal-starts
+            (ev-expand
+              dc
+              (ev-date 2026 6 5)
+              (ev-date 2026 6 8)))
+          (list
+            (list 2026 6 5)
+            (list 2026 6 6)
+            (list 2026 6 7)
+            (list 2026 6 8))))
+      (let
+        ((dc2 (ev-event (quote dc2) (ev-dt 2026 6 1 0 0) 30 {:freq :daily :count 3} 1)))
+        (ev-cal-check!
+          "count exhausted before window yields nothing"
+          (len
+            (ev-expand
+              dc2
+              (ev-date 2026 6 10)
+              (ev-date 2026 6 20)))
+          0))
+      (let
+        ((wk (ev-event (quote w) (ev-dt 2026 6 1 18 0) 90 {:freq :weekly :byday (list 0 2 4)} 1)))
+        (ev-cal-check!
+          "weekly byday mon/wed/fri first two weeks"
+          (ev-cal-shape
+            (ev-expand
+              wk
+              (ev-date 2026 6 1)
+              (ev-date 2026 6 13)))
+          (list
+            (list (list 2026 6 1) 0)
+            (list (list 2026 6 3) 2)
+            (list (list 2026 6 5) 4)
+            (list (list 2026 6 8) 0)
+            (list (list 2026 6 10) 2)
+            (list (list 2026 6 12) 4))))
+      (let
+        ((wu (ev-event (quote wu) (ev-dt 2026 6 1 18 0) 90 {:freq :weekly :until (ev-dt 2026 6 10 23 0) :byday (list 0 2)} 1)))
+        (ev-cal-check!
+          "weekly until clips trailing occurrences"
+          (ev-cal-starts
+            (ev-expand
+              wu
+              (ev-date 2026 6 1)
+              (ev-date 2026 7 1)))
+          (list
+            (list 2026 6 1)
+            (list 2026 6 3)
+            (list 2026 6 8)
+            (list 2026 6 10))))
+      (let
+        ((wi (ev-event (quote wi) (ev-dt 2026 6 1 18 0) 90 {:interval 2 :freq :weekly :byday (list 0)} 1)))
+        (ev-cal-check!
+          "weekly interval 2 skips alternate weeks"
+          (ev-cal-starts
+            (ev-expand
+              wi
+              (ev-date 2026 6 1)
+              (ev-date 2026 7 6)))
+          (list
+            (list 2026 6 1)
+            (list 2026 6 15)
+            (list 2026 6 29))))
+      (let
+        ((wd (ev-event (quote wd) (ev-dt 2026 6 3 12 0) 60 {:freq :weekly :count 3} 1)))
+        (ev-cal-check!
+          "weekly default byday is dtstart weekday"
+          (ev-cal-shape
+            (ev-expand
+              wd
+              (ev-date 2026 6 1)
+              (ev-date 2026 8 1)))
+          (list
+            (list (list 2026 6 3) 2)
+            (list (list 2026 6 10) 2)
+            (list (list 2026 6 17) 2))))
+      (let
+        ((wc (ev-event (quote wc) (ev-dt 2026 6 1 18 0) 90 {:freq :weekly :count 10 :byday (list 0 2)} 1)))
+        (ev-cal-check!
+          "weekly count window-independent (clip middle)"
+          (ev-cal-starts
+            (ev-expand
+              wc
+              (ev-date 2026 6 15)
+              (ev-date 2026 7 5)))
+          (list
+            (list 2026 6 15)
+            (list 2026 6 17)
+            (list 2026 6 22)
+            (list 2026 6 24)
+            (list 2026 6 29)
+            (list 2026 7 1))))
+      (let
+        ((wf (ev-event (quote wf) (ev-dt 2026 6 3 18 0) 90 {:freq :weekly :count 4 :byday (list 0 2 4)} 1)))
+        (ev-cal-check!
+          "first week skips byday earlier than dtstart"
+          (ev-cal-starts
+            (ev-expand
+              wf
+              (ev-date 2026 6 1)
+              (ev-date 2026 7 1)))
+          (list
+            (list 2026 6 3)
+            (list 2026 6 5)
+            (list 2026 6 8)
+            (list 2026 6 10))))
+      (let
+        ((md (ev-event (quote md) (ev-dt 2026 1 15 9 0) 60 {:bymonthday (list 15) :freq :monthly} 1)))
+        (do
+          (ev-cal-check!
+            "monthly bymonthday 15th"
+            (ev-cal-starts
+              (ev-expand
+                md
+                (ev-date 2026 1 1)
+                (ev-date 2026 4 1)))
+            (list
+              (list 2026 1 15)
+              (list 2026 2 15)
+              (list 2026 3 15)))
+          (ev-cal-check!
+            "monthly preserves time of day"
+            (ev-dt-tod
+              (get
+                (first
+                  (ev-expand
+                    md
+                    (ev-date 2026 1 1)
+                    (ev-date 2026 4 1)))
+                :start))
+            540)))
+      (let
+        ((mm (ev-event (quote mm) (ev-dt 2026 1 1 9 0) 60 {:bymonthday (list 1 15) :freq :monthly :count 4} 1)))
+        (ev-cal-check!
+          "monthly multiple bymonthday sorted within month"
+          (ev-cal-starts
+            (ev-expand
+              mm
+              (ev-date 2026 1 1)
+              (ev-date 2026 12 1)))
+          (list
+            (list 2026 1 1)
+            (list 2026 1 15)
+            (list 2026 2 1)
+            (list 2026 2 15))))
+      (let
+        ((ml (ev-event (quote ml) (ev-dt 2026 1 31 9 0) 60 {:bymonthday (list -1) :freq :monthly} 1)))
+        (ev-cal-check!
+          "monthly bymonthday -1 is last day"
+          (ev-cal-starts
+            (ev-expand
+              ml
+              (ev-date 2026 1 1)
+              (ev-date 2026 4 1)))
+          (list
+            (list 2026 1 31)
+            (list 2026 2 28)
+            (list 2026 3 31))))
+      (let
+        ((mn (ev-event (quote mn) (ev-dt 2026 1 1 9 0) 60 {:freq :monthly :byday (list {:ord 2 :wd 1})} 1)))
+        (ev-cal-check!
+          "monthly 2nd tuesday"
+          (ev-cal-shape
+            (ev-expand
+              mn
+              (ev-date 2026 1 1)
+              (ev-date 2026 4 1)))
+          (list
+            (list (list 2026 1 13) 1)
+            (list (list 2026 2 10) 1)
+            (list (list 2026 3 10) 1))))
+      (let
+        ((mz (ev-event (quote mz) (ev-dt 2026 1 1 9 0) 60 {:freq :monthly :byday (list {:ord -1 :wd 4})} 1)))
+        (ev-cal-check!
+          "monthly last friday"
+          (ev-cal-shape
+            (ev-expand
+              mz
+              (ev-date 2026 1 1)
+              (ev-date 2026 4 1)))
+          (list
+            (list (list 2026 1 30) 4)
+            (list (list 2026 2 27) 4)
+            (list (list 2026 3 27) 4))))
+      (let
+        ((m31 (ev-event (quote m31) (ev-dt 2026 1 31 9 0) 60 {:freq :monthly :count 4} 1)))
+        (ev-cal-check!
+          "monthly default day-of-month skips short months"
+          (ev-cal-starts
+            (ev-expand
+              m31
+              (ev-date 2026 1 1)
+              (ev-date 2026 12 1)))
+          (list
+            (list 2026 1 31)
+            (list 2026 3 31)
+            (list 2026 5 31)
+            (list 2026 7 31))))
+      (let
+        ((mi (ev-event (quote mi) (ev-dt 2026 1 10 9 0) 60 {:interval 3 :freq :monthly :count 3} 1)))
+        (ev-cal-check!
+          "monthly interval 3 steps by quarter"
+          (ev-cal-starts
+            (ev-expand
+              mi
+              (ev-date 2026 1 1)
+              (ev-date 2027 1 1)))
+          (list
+            (list 2026 1 10)
+            (list 2026 4 10)
+            (list 2026 7 10))))
+      (let
+        ((mc (ev-event (quote mc) (ev-dt 2026 1 5 9 0) 60 {:freq :monthly :count 12} 1)))
+        (ev-cal-check!
+          "monthly count window-independent (clip middle)"
+          (ev-cal-starts
+            (ev-expand
+              mc
+              (ev-date 2026 4 1)
+              (ev-date 2026 6 30)))
+          (list
+            (list 2026 4 5)
+            (list 2026 5 5)
+            (list 2026 6 5))))
+      (let
+        ((a (ev-event (quote a) (ev-dt 2026 6 2 10 0) 30 {:freq :daily :count 2} 1))
+          (b
+            (ev-event
+              (quote b)
+              (ev-dt 2026 6 1 9 0)
+              30
+              {:freq :daily :count 2}
+              1)))
+        (ev-cal-check!
+          "expand-all sorts merged occurrences by start"
+          (map
+            (fn (o) (list (get o :id) (ev-dt->civil (get o :start))))
+            (ev-expand-all
+              (list a b)
+              (ev-date 2026 6 1)
+              (ev-date 2026 7 1)))
+          (list
+            (list (quote b) (list 2026 6 1))
+            (list (quote b) (list 2026 6 2))
+            (list (quote a) (list 2026 6 2))
+            (list (quote a) (list 2026 6 3))))))))
+
+;; ---- EXDATE / RDATE exceptions ----
+(define
+  ev-cal-ex-run-all!
+  (fn
+    ()
+    (do
+      ;; EXDATE removes a matching occurrence from the recurrence
+      (let
+        ((ex
+           (ev-event-full
+             (quote standup)
+             (ev-dt 2026 6 1 9 0)
+             30
+             {:freq :daily :count 5}
+             1
+             (list (ev-dt 2026 6 3 9 0))
+             (list))))
+        (ev-cal-check!
+          "EXDATE excludes the matching occurrence"
+          (ev-cal-starts (ev-expand ex (ev-date 2026 6 1) (ev-date 2026 7 1)))
+          (list (list 2026 6 1) (list 2026 6 2) (list 2026 6 4) (list 2026 6 5))))
+      ;; EXDATE that matches nothing is a no-op
+      (let
+        ((ex2
+           (ev-event-full
+             (quote s)
+             (ev-dt 2026 6 1 9 0)
+             30
+             {:freq :daily :count 3}
+             1
+             (list (ev-dt 2026 6 9 9 0))
+             (list))))
+        (ev-cal-check!
+          "EXDATE not matching any occurrence is a no-op"
+          (len (ev-expand ex2 (ev-date 2026 6 1) (ev-date 2026 7 1)))
+          3))
+      ;; RDATE adds an explicit occurrence (within the window)
+      (let
+        ((rd
+           (ev-event-full
+             (quote s)
+             (ev-dt 2026 6 1 9 0)
+             30
+             {:freq :daily :count 3}
+             1
+             (list)
+             (list (ev-dt 2026 6 10 9 0)))))
+        (do
+          (ev-cal-check!
+            "RDATE adds an explicit occurrence, sorted in"
+            (ev-cal-starts (ev-expand rd (ev-date 2026 6 1) (ev-date 2026 7 1)))
+            (list (list 2026 6 1) (list 2026 6 2) (list 2026 6 3) (list 2026 6 10)))
+          (ev-cal-check!
+            "RDATE outside the window is dropped"
+            (len (ev-expand rd (ev-date 2026 6 1) (ev-date 2026 6 5)))
+            3)))
+      ;; RDATE coinciding with an rrule occurrence is de-duplicated
+      (let
+        ((rdup
+           (ev-event-full
+             (quote s)
+             (ev-dt 2026 6 1 9 0)
+             30
+             {:freq :daily :count 3}
+             1
+             (list)
+             (list (ev-dt 2026 6 2 9 0)))))
+        (ev-cal-check!
+          "RDATE duplicating an occurrence does not double it"
+          (len (ev-expand rdup (ev-date 2026 6 1) (ev-date 2026 7 1)))
+          3))
+      ;; EXDATE wins over RDATE for the same datetime
+      (let
+        ((both
+           (ev-event-full
+             (quote s)
+             (ev-dt 2026 6 1 9 0)
+             30
+             {:freq :daily :count 3}
+             1
+             (list (ev-dt 2026 6 2 9 0))
+             (list (ev-dt 2026 6 2 9 0)))))
+        (ev-cal-check!
+          "EXDATE wins over RDATE and the rrule for the same date"
+          (ev-cal-starts (ev-expand both (ev-date 2026 6 1) (ev-date 2026 7 1)))
+          (list (list 2026 6 1) (list 2026 6 3))))
+      ;; RDATE-only event (no rrule)
+      (let
+        ((ronly
+           (ev-event-full
+             (quote s)
+             (ev-dt 2026 6 1 9 0)
+             30
+             nil
+             1
+             (list)
+             (list (ev-dt 2026 6 5 9 0) (ev-dt 2026 6 3 9 0)))))
+        (ev-cal-check!
+          "RDATE-only event yields dtstart plus the extra dates, sorted"
+          (ev-cal-starts (ev-expand ronly (ev-date 2026 6 1) (ev-date 2026 7 1)))
+          (list (list 2026 6 1) (list 2026 6 3) (list 2026 6 5))))
+      ;; plain ev-event (no exception keys) is unaffected
+      (let
+        ((plain (ev-event (quote p) (ev-dt 2026 6 1 9 0) 30 {:freq :daily :count 3} 1)))
+        (ev-cal-check!
+          "plain event without exceptions expands unchanged"
+          (len (ev-expand plain (ev-date 2026 6 1) (ev-date 2026 7 1)))
+          3)))))
+
+;; ---- per-occurrence overrides (reschedule one instance) ----
+(define
+  ev-cal-ov-run-all!
+  (fn
+    ()
+    (let
+      ((base (ev-event (quote standup) (ev-dt 2026 6 1 9 0) 30 {:freq :daily :count 4} 1)))
+      (do
+        ;; reschedule one instance to a new time + duration
+        (let
+          ((moved (ev-with-override base (ev-dt 2026 6 2 9 0) (ev-dt 2026 6 2 14 0) 45)))
+          (let
+            ((occs (ev-expand moved (ev-date 2026 6 1) (ev-date 2026 6 5))))
+            (do
+              (ev-cal-check!
+                "override moves only the targeted instance"
+                (map (fn (o) (ev-dt-tod (get o :start))) occs)
+                (list 540 840 540 540))
+              (ev-cal-check!
+                "override applies the new duration"
+                (map (fn (o) (- (get o :end) (get o :start))) occs)
+                (list 30 45 30 30))
+              (ev-cal-check!
+                "override keeps the series length"
+                (len occs)
+                4))))
+        ;; an instance moved out of the window vacates its slot
+        (let
+          ((movedout (ev-with-override base (ev-dt 2026 6 2 9 0) (ev-dt 2026 6 20 9 0) 30)))
+          (ev-cal-check!
+            "instance moved out of window is dropped, slot vacated"
+            (ev-cal-starts (ev-expand movedout (ev-date 2026 6 1) (ev-date 2026 6 5)))
+            (list (list 2026 6 1) (list 2026 6 3) (list 2026 6 4))))
+        ;; override for a non-existent original start is a no-op
+        (let
+          ((noop (ev-with-override base (ev-dt 2026 6 9 9 0) (ev-dt 2026 6 9 14 0) 45)))
+          (ev-cal-check!
+            "override for a non-occurring start is a no-op"
+            (len (ev-expand noop (ev-date 2026 6 1) (ev-date 2026 6 5)))
+            4))
+        ;; overrides re-sort the agenda when an instance moves earlier
+        (let
+          ((early (ev-with-override base (ev-dt 2026 6 3 9 0) (ev-dt 2026 6 1 7 0) 30)))
+          (ev-cal-check!
+            "an instance moved earlier re-sorts into place"
+            (map (fn (o) (ev-dt-tod (get o :start))) (ev-expand early (ev-date 2026 6 1) (ev-date 2026 6 5)))
+            (list 420 540 540 540)))))))
+
+(define
+  ev-calendar-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-cal-pass 0)
+      (set! ev-cal-fail 0)
+      (set! ev-cal-failures (list))
+      (ev-cal-run-all!)
+      (ev-cal-ex-run-all!)
+      (ev-cal-ov-run-all!)
+      {:failures ev-cal-failures :total (+ ev-cal-pass ev-cal-fail) :passed ev-cal-pass :failed ev-cal-fail})))

lib/events/tests/federation.sx

@@ -0,0 +1,231 @@
+;; lib/events/tests/federation.sx — trust-gated cross-instance agenda merge.
+
+(define ev-fd-pass 0)
+(define ev-fd-fail 0)
+(define ev-fd-failures (list))
+
+(define
+  ev-fd-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-fd-pass (+ ev-fd-pass 1))
+      (do
+        (set! ev-fd-fail (+ ev-fd-fail 1))
+        (append!
+          ev-fd-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; Local schedule + two peers. Distinct start times make ordering legible.
+(define
+  ev-fd-local
+  (fn
+    ()
+    (ev/schedule
+      (ev/empty)
+      (quote yoga)
+      (ev-dt 2026 6 1 9 0)
+      60
+      nil
+      20)))
+
+(define
+  ev-fd-berlin
+  (fn
+    ()
+    (ev/peer
+      (quote berlin)
+      (ev/schedule
+        (ev/empty)
+        (quote meetup)
+        (ev-dt 2026 6 1 12 0)
+        90
+        nil
+        100)))) 
+
+(define
+  ev-fd-paris
+  (fn
+    ()
+    (ev/peer
+      (quote paris)
+      (ev/schedule
+        (ev/empty)
+        (quote salon)
+        (ev-dt 2026 6 1 15 0)
+        60
+        nil
+        30))))
+
+(define
+  ev-fd-run-all!
+  (fn
+    ()
+    (let
+      ((local (ev-fd-local))
+        (peers (list (ev-fd-berlin) (ev-fd-paris)))
+        (ws (ev-date 2026 6 1))
+        (we (ev-date 2026 6 2)))
+      (do
+        (ev-fd-check!
+          "trusts a peer in the trust set"
+          (ev/trusts? (list (quote berlin)) (quote berlin))
+          true)
+        (ev-fd-check!
+          "does not trust a peer outside the set"
+          (ev/trusts? (list (quote berlin)) (quote paris))
+          false)
+        (ev-fd-check!
+          "trusted-peers filters to the trust set"
+          (map ev/peer-id (ev/trusted-peers peers (list (quote berlin))))
+          (list (quote berlin)))
+        (let
+          ((fed (ev/federated-agenda local peers (list (quote berlin)) ws we)))
+          (do
+            (ev-fd-check!
+              "merge includes local + trusted peer only"
+              (map (fn (o) (list (get o :origin) (get o :id))) fed)
+              (list
+                (list :local (quote yoga))
+                (list (quote berlin) (quote meetup))))
+            (ev-fd-check!
+              "merge is sorted by start"
+              (map (fn (o) (get o :start)) fed)
+              (list
+                (ev-dt 2026 6 1 9 0)
+                (ev-dt 2026 6 1 12 0)))
+            (ev-fd-check!
+              "untrusted peer (paris) contributes nothing"
+              (len (ev/from-origin fed (quote paris)))
+              0)
+            (ev-fd-check!
+              "local occurrences tagged :local"
+              (map (fn (o) (get o :id)) (ev/from-origin fed :local))
+              (list (quote yoga)))
+            (ev-fd-check!
+              "peer occurrences tagged with the peer id"
+              (map
+                (fn (o) (get o :id))
+                (ev/from-origin fed (quote berlin)))
+              (list (quote meetup)))))
+        (let
+          ((fed2 (ev/federated-agenda local peers (list (quote berlin) (quote paris)) ws we)))
+          (ev-fd-check!
+            "trusting both peers merges all three, sorted"
+            (map (fn (o) (list (get o :origin) (get o :id))) fed2)
+            (list
+              (list :local (quote yoga))
+              (list (quote berlin) (quote meetup))
+              (list (quote paris) (quote salon)))))
+        (let
+          ((fed3 (ev/federated-agenda local peers (list) ws we)))
+          (do
+            (ev-fd-check!
+              "empty trust yields only local occurrences"
+              (map (fn (o) (get o :origin)) fed3)
+              (list :local))
+            (ev-fd-check!
+              "empty trust still includes local"
+              (len fed3)
+              1)))
+        (let
+          ((rpeer (ev/peer (quote tokyo) (ev/schedule (ev/empty) (quote standup) (ev-dt 2026 6 1 8 0) 15 {:freq :daily :count 3} 5))))
+          (let
+            ((pa (ev/peer-agenda rpeer ws (ev-date 2026 6 4))))
+            (do
+              (ev-fd-check!
+                "peer recurrence expands in the window"
+                (len pa)
+                3)
+              (ev-fd-check!
+                "every peer occurrence is tagged with the peer id"
+                (map (fn (o) (get o :origin)) pa)
+                (list (quote tokyo) (quote tokyo) (quote tokyo))))))))))
+
+;; ---- federated free/busy ----
+(define
+  ev-fd-fb-run-all!
+  (fn
+    ()
+    (let
+      ((local-db
+         (ev-avail-db
+           (list (ev-occ (quote yoga) (ev-dt 2026 6 1 9 0) 60))
+           (list (list (quote nia) (str (quote yoga) "@" (ev-dt 2026 6 1 9 0))))))
+        (berlin
+          (ev/peer-with-busy
+            (quote berlin)
+            (ev/empty)
+            (list
+              (list (quote nia)
+                (list (list (ev-dt 2026 6 1 14 0) (ev-dt 2026 6 1 15 0)))))))
+        (paris
+          (ev/peer-with-busy
+            (quote paris)
+            (ev/empty)
+            (list
+              (list (quote nia)
+                (list (list (ev-dt 2026 6 1 11 0) (ev-dt 2026 6 1 12 0))))))))
+      (let
+        ((peers (list berlin paris)))
+        (do
+          ;; peer-busy reads a peer's published intervals
+          (ev-fd-check!
+            "peer-busy returns published intervals for an actor"
+            (ev/peer-busy berlin (quote nia))
+            (list (list (ev-dt 2026 6 1 14 0) (ev-dt 2026 6 1 15 0))))
+          (ev-fd-check!
+            "peer-busy empty for an actor with nothing published"
+            (ev/peer-busy berlin (quote zed))
+            (list))
+          ;; federated-busy unions local + trusted-peer busy, sorted
+          (ev-fd-check!
+            "federated-busy unions local + trusted peer, sorted"
+            (ev/federated-busy local-db (list berlin) (list (quote berlin)) (quote nia))
+            (list
+              (list (ev-dt 2026 6 1 9 0) (ev-dt 2026 6 1 10 0))
+              (list (ev-dt 2026 6 1 14 0) (ev-dt 2026 6 1 15 0))))
+          (ev-fd-check!
+            "untrusted peer busy is excluded from federated-busy"
+            (ev/federated-busy local-db peers (list (quote berlin)) (quote nia))
+            (list
+              (list (ev-dt 2026 6 1 9 0) (ev-dt 2026 6 1 10 0))
+              (list (ev-dt 2026 6 1 14 0) (ev-dt 2026 6 1 15 0))))
+          ;; federated-free? considers both local and trusted-peer commitments
+          (ev-fd-check!
+            "free locally and on peers in an open window"
+            (ev/federated-free? local-db peers (list (quote berlin)) (quote nia) (ev-dt 2026 6 1 16 0) (ev-dt 2026 6 1 17 0))
+            true)
+          (ev-fd-check!
+            "not free during a LOCAL booking"
+            (ev/federated-free? local-db peers (list (quote berlin)) (quote nia) (ev-dt 2026 6 1 9 30) (ev-dt 2026 6 1 9 45))
+            false)
+          (ev-fd-check!
+            "not free during a TRUSTED PEER busy interval"
+            (ev/federated-free? local-db peers (list (quote berlin)) (quote nia) (ev-dt 2026 6 1 14 30) (ev-dt 2026 6 1 14 45))
+            false)
+          (ev-fd-check!
+            "free during an UNTRUSTED peer's busy interval (paris not trusted)"
+            (ev/federated-free? local-db peers (list (quote berlin)) (quote nia) (ev-dt 2026 6 1 11 15) (ev-dt 2026 6 1 11 45))
+            true)
+          (ev-fd-check!
+            "not free once paris is trusted too"
+            (ev/federated-free? local-db peers (list (quote berlin) (quote paris)) (quote nia) (ev-dt 2026 6 1 11 15) (ev-dt 2026 6 1 11 45))
+            false)
+          (ev-fd-check!
+            "federated-free? half-open at a busy edge"
+            (ev/federated-free? local-db peers (list (quote berlin)) (quote nia) (ev-dt 2026 6 1 15 0) (ev-dt 2026 6 1 16 0))
+            true))))))
+
+(define
+  ev-federation-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-fd-pass 0)
+      (set! ev-fd-fail 0)
+      (set! ev-fd-failures (list))
+      (ev-fd-run-all!)
+      (ev-fd-fb-run-all!)
+      {:failures ev-fd-failures :total (+ ev-fd-pass ev-fd-fail) :passed ev-fd-pass :failed ev-fd-fail})))

lib/events/tests/notify.sx

@@ -0,0 +1,77 @@
+;; lib/events/tests/notify.sx — durable notification delivery flows.
+
+(define ev-nt-pass 0)
+(define ev-nt-fail 0)
+(define ev-nt-failures (list))
+
+(define
+  ev-nt-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-nt-pass (+ ev-nt-pass 1))
+      (do
+        (set! ev-nt-fail (+ ev-nt-fail 1))
+        (append!
+          ev-nt-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; Each case runs a Scheme flow program (notify flows preloaded) and asserts on
+;; the SX-native result. Scheme symbols come back as strings.
+(define
+  ev-nt-run-all!
+  (fn
+    ()
+    (do
+      (ev-nt-check!
+        "reminder delivers on the first attempt"
+        (ev/notify-run
+          "(define s (flow/start (ev-deliver-reminder 3) (list (quote m1) (quote alice) (quote hello))))\n           (flow-run-host (lambda (k p) (list (quote ok) (quote sent))) 5)\n           (list (flow/status (car (cdr s))) (flow/result (car (cdr s))))")
+        (list "done" (list "delivered" "m1" 1)))
+      (ev-nt-check!
+        "reminder retries a transient failure then delivers"
+        (ev/notify-run
+          "(define hits 0)\n           (define s (flow/start (ev-deliver-reminder 3) (list (quote m1) (quote bob) (quote hi))))\n           (flow-run-host (lambda (k p) (begin (set! hits (+ hits 1)) (if (< hits 2) (list (quote retry) (quote down)) (list (quote ok) (quote sent))))) 10)\n           (list (flow/result (car (cdr s))) hits)")
+        (list (list "delivered" "m1" 2) 2))
+      (ev-nt-check!
+        "reminder gives up after maxn attempts"
+        (ev/notify-run
+          "(define s (flow/start (ev-deliver-reminder 2) (list (quote m1) (quote x) (quote y))))\n           (flow-run-host (lambda (k p) (list (quote retry) (quote down))) 10)\n           (flow/result (car (cdr s)))")
+        (list "failed" "m1" "down"))
+      (ev-nt-check!
+        "redelivery of the same id sends only once (at-least-once, idempotent)"
+        (ev/notify-run
+          "(define sent (list)) (define deliveries 0)\n           (define (xport k p)\n             (let ((id (ev-msg-id p)))\n               (if (ev-mem id sent)\n                   (list (quote ok) (quote duplicate))\n                   (begin (set! sent (cons id sent)) (set! deliveries (+ deliveries 1)) (list (quote ok) (quote sent))))))\n           (define s1 (flow/start (ev-deliver-reminder 3) (list (quote m1) (quote a) (quote hi))))\n           (flow-run-host xport 5)\n           (define s2 (flow/start (ev-deliver-reminder 3) (list (quote m1) (quote a) (quote hi))))\n           (flow-run-host xport 5)\n           (list deliveries (flow/result (car (cdr s2))))")
+        (list 1 (list "delivered" "m1" 1)))
+      (ev-nt-check!
+        "digest delivers every message in the batch"
+        (ev/notify-run
+          "(define s (flow/start (ev-deliver-digest 3) (list (list (quote a) (quote u1) (quote hi)) (list (quote b) (quote u2) (quote yo)))))\n           (flow-run-host (lambda (k p) (list (quote ok) (quote sent))) 10)\n           (flow/result (car (cdr s)))")
+        (list
+          (list "delivered" "a" 1)
+          (list "delivered" "b" 1)))
+      (ev-nt-check!
+        "digest reports per-message outcomes independently"
+        (ev/notify-run
+          "(define (xport k p)\n             (let ((id (ev-msg-id p)))\n               (if (equal? id (quote b)) (list (quote retry) (quote flaky)) (list (quote ok) (quote sent)))))\n           (define s (flow/start (ev-deliver-digest 2) (list (list (quote a) (quote u1) (quote hi)) (list (quote b) (quote u2) (quote yo)) (list (quote c) (quote u3) (quote ya)))))\n           (flow-run-host xport 12)\n           (flow/result (car (cdr s)))")
+        (list
+          (list "delivered" "a" 1)
+          (list "failed" "b" "flaky")
+          (list "delivered" "c" 1)))
+      (ev-nt-check!
+        "delivery suspends until the transport responds"
+        (ev/notify-run
+          "(define s (flow/start (ev-deliver-reminder 3) (list (quote m1) (quote a) (quote hi))))\n           (flow/status (car (cdr s)))")
+        "suspended"))))
+
+(define
+  ev-notify-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-nt-pass 0)
+      (set! ev-nt-fail 0)
+      (set! ev-nt-failures (list))
+      (ev-nt-run-all!)
+      {:failures ev-nt-failures :total (+ ev-nt-pass ev-nt-fail) :passed ev-nt-pass :failed ev-nt-fail})))

lib/events/tests/reminders.sx

@@ -0,0 +1,276 @@
+;; lib/events/tests/reminders.sx — reminder + digest derivation from the agenda.
+
+(define ev-rm-pass 0)
+(define ev-rm-fail 0)
+(define ev-rm-failures (list))
+
+(define
+  ev-rm-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-rm-pass (+ ev-rm-pass 1))
+      (do
+        (set! ev-rm-fail (+ ev-rm-fail 1))
+        (append!
+          ev-rm-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; A store with a weekly class (Mon+Wed 18:00, 60m, 4 occurrences) and a one-off
+;; talk; durable bookings on a persist backend.
+(define
+  ev-rm-store
+  (fn
+    ()
+    (ev/schedule
+      (ev/schedule
+        (ev/empty)
+        (quote yoga)
+        (ev-dt 2026 6 1 18 0)
+        60
+        {:freq :weekly :count 4 :byday (list 0 2)}
+        20)
+      (quote talk)
+      (ev-dt 2026 6 2 12 0)
+      30
+      nil
+      50)))
+
+(define
+  ev-rm-run-all!
+  (fn
+    ()
+    (let
+      ((store (ev-rm-store)) (b (persist/open)))
+      (let
+        ((occs (ev/agenda store (ev-date 2026 6 1) (ev-date 2026 7 1))))
+        (do
+          (ev/book-occ! b store (quote nia) (first occs))
+          (ev/book-occ! b store (quote ola) (first occs))
+          (ev/book-occ!
+            b
+            store
+            (quote ola)
+            (ev-occ
+              (quote talk)
+              (ev-dt 2026 6 2 12 0)
+              30))
+          (do
+            (let
+              ((rs (ev/occurrence-reminders b (first occs) 60)))
+              (do
+                (ev-rm-check!
+                  "one reminder per booked attendee"
+                  (len rs)
+                  2)
+                (ev-rm-check!
+                  "reminder fires lead minutes before start"
+                  (get (first rs) :fire-at)
+                  (-
+                    (ev-dt
+                      2026
+                      6
+                      1
+                      18
+                      0)
+                    60))
+                (ev-rm-check!
+                  "reminder idempotency key encodes occ/recipient/lead"
+                  (get (first rs) :id)
+                  (str
+                    (ev-occ-key (first occs))
+                    "/"
+                    (quote nia)
+                    "/"
+                    60))
+                (ev-rm-check!
+                  "reminder names the event"
+                  (get (first rs) :event)
+                  (quote yoga))))
+            (ev-rm-check!
+              "unbooked occurrence has no reminders"
+              (len
+                (ev/occurrence-reminders b (ev-occ (quote yoga) (ev-dt 2026 6 3 18 0) 60) 60))
+              0)
+            (let
+              ((all (ev/agenda-reminders b store (ev-date 2026 6 1) (ev-date 2026 7 1) 60)))
+              (do
+                (ev-rm-check!
+                  "agenda reminders cover all bookings"
+                  (len all)
+                  3)
+                (ev-rm-check!
+                  "agenda reminders sorted by fire-at"
+                  (map (fn (r) (get r :fire-at)) all)
+                  (list
+                    (-
+                      (ev-dt
+                        2026
+                        6
+                        1
+                        18
+                        0)
+                      60)
+                    (-
+                      (ev-dt
+                        2026
+                        6
+                        1
+                        18
+                        0)
+                      60)
+                    (-
+                      (ev-dt
+                        2026
+                        6
+                        2
+                        12
+                        0)
+                      60)))))
+            (let
+              ((all (ev/agenda-reminders b store (ev-date 2026 6 1) (ev-date 2026 7 1) 60)))
+              (do
+                (ev-rm-check!
+                  "nothing due before the first fire-at"
+                  (len
+                    (ev/due-reminders
+                      all
+                      (-
+                        (ev-dt
+                          2026
+                          6
+                          1
+                          17
+                          0)
+                        1)))
+                  0)
+                (ev-rm-check!
+                  "the two yoga reminders are due at 17:00"
+                  (len
+                    (ev/due-reminders
+                      all
+                      (ev-dt
+                        2026
+                        6
+                        1
+                        17
+                        0)))
+                  2)
+                (ev-rm-check!
+                  "all reminders due once past the last fire-at"
+                  (len
+                    (ev/due-reminders
+                      all
+                      (ev-dt
+                        2026
+                        6
+                        2
+                        12
+                        0)))
+                  3)))
+            (let
+              ((r (first (ev/occurrence-reminders b (first occs) 60))))
+              (ev-rm-check!
+                "reminder projects to (id recipient body)"
+                (ev/reminder->msg r)
+                (list
+                  (str
+                    (ev-occ-key (first occs))
+                    "/"
+                    (quote nia)
+                    "/"
+                    60)
+                  (quote nia)
+                  (list
+                    :reminder (quote yoga)
+                    (ev-dt
+                      2026
+                      6
+                      1
+                      18
+                      0)))))
+            (let
+              ((dig (ev/agenda-digest b store (quote ola) (ev-date 2026 6 1) (ev-date 2026 7 1))))
+              (do
+                (ev-rm-check!
+                  "digest is addressed to the actor"
+                  (get dig :recipient)
+                  (quote ola))
+                (ev-rm-check!
+                  "digest lists the actor's booked occurrences"
+                  (map (fn (it) (get it :event)) (get dig :items))
+                  (list (quote yoga) (quote talk)))))
+            (let
+              ((empty-dig (ev/agenda-digest b store (quote nobody) (ev-date 2026 6 1) (ev-date 2026 7 1))))
+              (ev-rm-check!
+                "digest empty for an actor with no bookings"
+                (get empty-dig :items)
+                (list)))))))))
+
+;; ---- reschedule notifications ----
+(define
+  ev-rm-rs-run-all!
+  (fn
+    ()
+    (let
+      ((b (persist/open))
+        (ev (ev-event (quote yoga) (ev-dt 2026 6 1 9 0) 60 {:freq :daily :count 3} 20)))
+      (let
+        ((occ2 (ev-occ (quote yoga) (ev-dt 2026 6 2 9 0) 60)))
+        (do
+          (ev/book-occ! b (ev/add-event (ev/empty) ev) (quote nia) occ2)
+          (ev/book-occ! b (ev/add-event (ev/empty) ev) (quote ola) occ2)
+          ;; reschedule the Jun 2 occurrence to 14:00 / 90 min
+          (let
+            ((moved (ev-with-override ev (ev-dt 2026 6 2 9 0) (ev-dt 2026 6 2 14 0) 90)))
+            (let
+              ((ns (ev/reschedule-notifications b moved)))
+              (do
+                (ev-rm-check!
+                  "every booked attendee is notified of the reschedule"
+                  (map (fn (n) (get n :recipient)) ns)
+                  (list (quote nia) (quote ola)))
+                (ev-rm-check!
+                  "reschedule carries old and new start"
+                  (list (get (first ns) :old-start) (get (first ns) :new-start))
+                  (list (ev-dt 2026 6 2 9 0) (ev-dt 2026 6 2 14 0)))
+                (ev-rm-check!
+                  "reschedule carries the new duration"
+                  (get (first ns) :new-duration)
+                  90)
+                (ev-rm-check!
+                  "reschedule idempotency key encodes original key + new start"
+                  (get (first ns) :id)
+                  (str (ev-occ-key occ2) "/reschedule/" (ev-dt 2026 6 2 14 0)))
+                (ev-rm-check!
+                  "reschedule projects to notify wire shape"
+                  (ev/reschedule-notify->msg (first ns))
+                  (list
+                    (str (ev-occ-key occ2) "/reschedule/" (ev-dt 2026 6 2 14 0))
+                    (quote nia)
+                    (list :rescheduled (quote yoga) (ev-dt 2026 6 2 9 0) (ev-dt 2026 6 2 14 0)))))))
+          ;; an override on an occurrence nobody booked notifies no one
+          (let
+            ((moved2 (ev-with-override ev (ev-dt 2026 6 3 9 0) (ev-dt 2026 6 3 10 0) 60)))
+            (ev-rm-check!
+              "rescheduling an unbooked occurrence notifies no one"
+              (len (ev/reschedule-notifications b moved2))
+              0))
+          ;; an event with no overrides yields no reschedule notifications
+          (ev-rm-check!
+            "event without overrides has no reschedule notifications"
+            (len (ev/reschedule-notifications b ev))
+            0))))))
+
+(define
+  ev-reminders-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-rm-pass 0)
+      (set! ev-rm-fail 0)
+      (set! ev-rm-failures (list))
+      (ev-rm-run-all!)
+      (ev-rm-rs-run-all!)
+      {:failures ev-rm-failures :total (+ ev-rm-pass ev-rm-fail) :passed ev-rm-pass :failed ev-rm-fail})))

lib/events/tests/ticket.sx

@@ -0,0 +1,252 @@
+;; lib/events/tests/ticket.sx — paid-ticket contract + settlement orchestration.
+
+(define ev-tk-pass 0)
+(define ev-tk-fail 0)
+(define ev-tk-failures (list))
+
+(define
+  ev-tk-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! ev-tk-pass (+ ev-tk-pass 1))
+      (do
+        (set! ev-tk-fail (+ ev-tk-fail 1))
+        (append!
+          ev-tk-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+(define
+  ev-tk-run-all!
+  (fn
+    ()
+    (do
+      (let
+        ((req (ev/checkout-request "occ1" (quote nia) 1500 "GBP" "ref-1")))
+        (do
+          (ev-tk-check!
+            "checkout-request is tagged"
+            (ev/checkout-request? req)
+            true)
+          (ev-tk-check!
+            "payment-result is not a checkout-request"
+            (ev/checkout-request? (ev/payment-paid "o" (quote a) "r"))
+            false)
+          (ev-tk-check!
+            "request occ-key accessor"
+            (ev/req-occ-key req)
+            "occ1")
+          (ev-tk-check!
+            "request actor accessor"
+            (ev/req-actor req)
+            (quote nia))
+          (ev-tk-check!
+            "request amount accessor"
+            (ev/req-amount req)
+            1500)
+          (ev-tk-check!
+            "request currency accessor"
+            (ev/req-currency req)
+            "GBP")
+          (ev-tk-check! "request ref accessor" (ev/req-ref req) "ref-1")))
+      (let
+        ((res (ev/payment-paid "occ1" (quote nia) "ref-1")))
+        (do
+          (ev-tk-check!
+            "payment-result is tagged"
+            (ev/payment-result? res)
+            true)
+          (ev-tk-check! "result status accessor" (ev/result-status res) :paid)
+          (ev-tk-check!
+            "failed constructor carries status"
+            (ev/result-status (ev/payment-failed "o" (quote a) "r"))
+            :failed)
+          (ev-tk-check!
+            "expired constructor carries status"
+            (ev/result-status (ev/payment-expired "o" (quote a) "r"))
+            :expired)))
+      (let
+        ((b (persist/open)))
+        (do
+          (let
+            ((r (ev/request-ticket! b "show" 1 (quote a) 2000 "GBP" "ref-a")))
+            (do
+              (ev-tk-check!
+                "request-ticket awaiting-payment"
+                (get r :status)
+                :awaiting-payment)
+              (ev-tk-check!
+                "request-ticket returns a checkout-request"
+                (ev/checkout-request? (get r :request))
+                true)
+              (ev-tk-check!
+                "checkout-request carries the amount"
+                (ev/req-amount (get r :request))
+                2000)))
+          (ev-tk-check!
+            "held seat reserves capacity"
+            (ev/seats-left b "show" 1)
+            0)
+          (ev-tk-check!
+            "second buyer is full while payment pends"
+            (get
+              (ev/request-ticket!
+                b
+                "show"
+                1
+                (quote c)
+                2000
+                "GBP"
+                "ref-c")
+              :status)
+            :full)
+          (ev-tk-check!
+            "held seat state pending"
+            (ev/seat-state b "show" (quote a))
+            :held)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/request-ticket!
+            b
+            "gig"
+            2
+            (quote a)
+            2000
+            "GBP"
+            "ref-a")
+          (let
+            ((s (ev/settle-payment! b (ev/payment-paid "gig" (quote a) "ref-a"))))
+            (ev-tk-check! "settle paid confirms" (get s :status) :confirmed))
+          (ev-tk-check!
+            "confirmed seat state"
+            (ev/seat-state b "gig" (quote a))
+            :confirmed)
+          (ev-tk-check!
+            "redelivered paid is still confirmed (idempotent)"
+            (get
+              (ev/settle-payment!
+                b
+                (ev/payment-paid "gig" (quote a) "ref-a"))
+              :status)
+            :confirmed)
+          (ev-tk-check!
+            "still exactly one seat taken"
+            (ev-booking-count b "gig")
+            1)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/request-ticket!
+            b
+            "fail"
+            1
+            (quote a)
+            2000
+            "GBP"
+            "ref-a")
+          (ev-tk-check!
+            "seat held before failure"
+            (ev/seats-left b "fail" 1)
+            0)
+          (let
+            ((s (ev/settle-payment! b (ev/payment-failed "fail" (quote a) "ref-a"))))
+            (ev-tk-check! "settle failed releases" (get s :status) :released))
+          (ev-tk-check!
+            "released seat frees capacity"
+            (ev/seats-left b "fail" 1)
+            1)
+          (ev-tk-check!
+            "redelivered failure is a noop"
+            (get
+              (ev/settle-payment!
+                b
+                (ev/payment-failed "fail" (quote a) "ref-a"))
+              :status)
+            :noop)
+          (ev-tk-check!
+            "freed seat available to next buyer"
+            (get
+              (ev/request-ticket!
+                b
+                "fail"
+                1
+                (quote c)
+                2000
+                "GBP"
+                "ref-c")
+              :status)
+            :awaiting-payment)
+          (ev/request-ticket!
+            b
+            "exp"
+            1
+            (quote a)
+            2000
+            "GBP"
+            "ref-a")
+          (ev-tk-check!
+            "settle expired releases"
+            (get
+              (ev/settle-payment!
+                b
+                (ev/payment-expired "exp" (quote a) "ref-a"))
+              :status)
+            :released)))
+      (let
+        ((b (persist/open)))
+        (do
+          (ev/request-ticket!
+            b
+            "race"
+            1
+            (quote a)
+            2000
+            "GBP"
+            "ref-a")
+          (ev/settle-payment!
+            b
+            (ev/payment-expired "race" (quote a) "ref-a"))
+          (ev-tk-check!
+            "late paid for a vanished hold needs a refund"
+            (get
+              (ev/settle-payment!
+                b
+                (ev/payment-paid "race" (quote a) "ref-a"))
+              :status)
+            :paid-but-no-hold)
+          (ev-tk-check!
+            "no phantom seat created"
+            (ev-booking-count b "race")
+            0)))
+      (let
+        ((b (persist/open)))
+        (do
+          (let
+            ((start (ev/request-ticket! b "e2e" 3 (quote nia) 2500 "GBP" "ref-nia")))
+            (ev/settle-payment!
+              b
+              (ev/payment-paid
+                (ev/req-occ-key (get start :request))
+                (ev/req-actor (get start :request))
+                (ev/req-ref (get start :request)))))
+          (ev-tk-check!
+            "e2e roster holds the buyer"
+            (ev/roster b "e2e")
+            (list (quote nia)))
+          (ev-tk-check!
+            "e2e seat confirmed"
+            (ev/seat-state b "e2e" (quote nia))
+            :confirmed))))))
+
+(define
+  ev-ticket-tests-run!
+  (fn
+    ()
+    (do
+      (set! ev-tk-pass 0)
+      (set! ev-tk-fail 0)
+      (set! ev-tk-failures (list))
+      (ev-tk-run-all!)
+      {:failures ev-tk-failures :total (+ ev-tk-pass ev-tk-fail) :passed ev-tk-pass :failed ev-tk-fail})))

lib/events/ticket.sx

@@ -0,0 +1,101 @@
+;; lib/events/ticket.sx — paid-ticket contract between events and commerce.
+;;
+;; A paid booking spans two subsystems. events does NOT import commerce; instead
+;; this module defines the CONTRACT — the two messages on the wire — and the
+;; events-side orchestration over provisional holds (booking.sx). commerce
+;; imports these shapes; the dependency only points one way.
+;;
+;;   checkout-request   events -> commerce   "take payment for this seat"
+;;     {:kind :events.checkout :occ-key :actor :amount :currency :ref}
+;;
+;;   payment-result     commerce -> events   "here's how payment went"
+;;     {:kind :events.payment  :occ-key :actor :ref :status}
+;;        :status ∈ :paid | :failed | :expired
+;;
+;; Flow: ev/request-ticket! places a capacity-safe HOLD (reserving the seat so
+;; it can't be oversold while payment pends) and returns a checkout-request to
+;; hand to commerce. When commerce reports back, ev/settle-payment! confirms the
+;; hold on :paid or releases it otherwise. Settlement is idempotent — an
+;; at-least-once redelivery of the same result is safe. `ref` is the opaque
+;; correlation/idempotency id; occ-key + actor locate the hold, so settlement
+;; needs no side table.
+
+;; ---- contract: checkout request (events -> commerce) ----
+
+(define
+  ev/checkout-request
+  (fn (occ-key actor amount currency ref) {:actor actor :amount amount :kind :events.checkout :ref ref :currency currency :occ-key occ-key}))
+
+(define
+  ev/checkout-request?
+  (fn (m) (and (dict? m) (= (get m :kind) :events.checkout))))
+
+(define ev/req-occ-key (fn (r) (get r :occ-key)))
+(define ev/req-actor (fn (r) (get r :actor)))
+(define ev/req-amount (fn (r) (get r :amount)))
+(define ev/req-currency (fn (r) (get r :currency)))
+(define ev/req-ref (fn (r) (get r :ref)))
+
+;; ---- contract: payment result (commerce -> events) ----
+
+(define ev/payment-result (fn (occ-key actor ref status) {:actor actor :kind :events.payment :status status :ref ref :occ-key occ-key}))
+
+(define
+  ev/payment-result?
+  (fn (m) (and (dict? m) (= (get m :kind) :events.payment))))
+
+(define ev/result-occ-key (fn (r) (get r :occ-key)))
+(define ev/result-actor (fn (r) (get r :actor)))
+(define ev/result-ref (fn (r) (get r :ref)))
+(define ev/result-status (fn (r) (get r :status)))
+
+(define
+  ev/payment-paid
+  (fn (occ-key actor ref) (ev/payment-result occ-key actor ref :paid)))
+(define
+  ev/payment-failed
+  (fn (occ-key actor ref) (ev/payment-result occ-key actor ref :failed)))
+(define
+  ev/payment-expired
+  (fn (occ-key actor ref) (ev/payment-result occ-key actor ref :expired)))
+
+;; ---- orchestration ----
+
+;; Begin a paid booking: place a capacity-safe hold and, if reserved, return a
+;; checkout-request for commerce. :full when no seat; :already when the actor
+;; already holds/booked this occurrence (no duplicate request).
+(define
+  ev/request-ticket!
+  (fn
+    (b occ-key capacity actor amount currency ref)
+    (let
+      ((h (ev/hold! b occ-key capacity actor)))
+      (cond
+        ((= (get h :status) :held) {:seat (get h :seat) :request (ev/checkout-request occ-key actor amount currency ref) :status :awaiting-payment})
+        ((= (get h :status) :already) {:seat (get h :seat) :status :already})
+        (else {:capacity capacity :status :full})))))
+
+;; Settle a payment result from commerce. :paid confirms the hold; :failed /
+;; :expired release it. Idempotent: a redelivered :paid stays :confirmed, a
+;; redelivered release is a :noop. If a :paid arrives for a hold that is already
+;; gone (released/expired first), returns :paid-but-no-hold so the caller can
+;; trigger a refund.
+(define
+  ev/settle-payment!
+  (fn
+    (b result)
+    (let
+      ((occ-key (ev/result-occ-key result))
+        (actor (ev/result-actor result))
+        (ref (ev/result-ref result)))
+      (if
+        (= (ev/result-status result) :paid)
+        (let
+          ((c (ev/confirm! b occ-key actor)))
+          (cond
+            ((= (get c :status) :confirmed) {:actor actor :status :confirmed :ref ref})
+            ((= (get c :status) :already-confirmed) {:actor actor :status :confirmed :ref ref})
+            (else {:actor actor :status :paid-but-no-hold :ref ref})))
+        (let
+          ((r (ev/release! b occ-key actor)))
+          (if (= (get r :status) :released) {:actor actor :status :released :ref ref} {:actor actor :status :noop :ref ref}))))))

plans/events-on-sx.md

@@ -18,7 +18,7 @@ capacity rules, transactional booking, and a flow-driven notification dispatcher
 
 ## Status (rolling)
 
-`bash lib/events/conformance.sh` → **0/0** (not yet started)
+`bash lib/events/conformance.sh` → **272/272** (Phases 1-4 + 6 ext: fed f/b, waitlist, EXDATE/RDATE, overrides, booking-notify, reschedule-notify)
 
 ## Ground rules
 
@@ -54,28 +54,185 @@ lib/events/api.sx ── (events/schedule) (events/book) (events/agenda) ──
 ```
 
 ## Phase 1 — Calendar + recurrence
-- [ ] `calendar.sx` — event facts, RRULE expansion in a window
-- [ ] `availability.sx` — free/busy rules
-- [ ] `api.sx` + tests + scoreboard + conformance.sh
+- [x] `calendar.sx` — event facts, RRULE expansion in a window (DAILY/WEEKLY)
+- [x] `calendar.sx` — MONTHLY (bymonthday + nth-weekday byday)
+- [x] `availability.sx` — free/busy rules (busy/conflict/busy_in on Datalog)
+- [x] `availability.sx` — next-free slot search (same rules, different bindings)
+- [x] `api.sx` — public entry points (schedule/agenda/book/free/next-free/conflicts)
+- [x] tests + scoreboard + conformance.sh (73/73)
 
 ## Phase 2 — Ticketing + booking
-- [ ] capacity rules; transactional booking → `persist` (no overbooking)
-- [ ] paid tickets compose with `commerce` order flow
-- [ ] tests: capacity edge, double-book guard, conflict detection
+- [x] capacity rules; transactional booking → `persist` (no overbooking)
+- [x] wire `booking.sx` into `api.sx` (persist-backed `ev/book-occ!` + derived availability)
+- [x] cancellation (tombstone events) + seat release
+- [x] provisional holds (hold/confirm/release) — reserve a seat during pending payment
+- [x] paid tickets compose with `commerce` order flow (contract module over holds)
+- [x] tests: capacity edge, double-book guard, conflict detection
 
 ## Phase 3 — Notification delivery (flow)
-- [ ] `notify.sx` — reminder/digest flows over injected transport
-- [ ] retry/backoff on transport failure (flow suspend/resume)
-- [ ] tests: delivery success, retry path, idempotent re-send
+- [x] `notify.sx` — reminder/digest flows over injected transport
+- [x] retry/backoff on transport failure (flow suspend/resume)
+- [x] tests: delivery success, retry path, idempotent re-send
+- [x] wire reminders to occurrences (`reminders.sx` — derive from agenda + roster)
 - [ ] NOTE: shared with `feed/notify` — candidate for later extraction to a
-  `delivery-on-sx` once a second consumer is real
+  `delivery-on-sx` once a second consumer is real. **Delivery core
+  (request→dispatch→resume, idempotent, bounded retry) is the extraction seam.**
 
 ## Phase 4 — Federation
-- [ ] cross-instance events (peer calendar) — trust-gated stub
-- [ ] tests: federated agenda merge
+- [x] cross-instance events (peer calendar) — trust-gated stub
+- [x] tests: federated agenda merge
+- [x] federated availability/free-busy across trusted peers
+- [ ] real transport behind `ev/peer-agenda` (fed-sx / signed fetch)
 
 ## Progress log
-(loop fills this in)
+
+- 2026-06-07 — Reschedule notifications (extension). When an event carries
+  per-occurrence overrides, `ev/reschedule-notifications` reads the roster at
+  each overridden occurrence's ORIGINAL occ-key and produces a reschedule
+  message per booked attendee (old-start, new-start, new-duration). Idempotency
+  key = original-key/reschedule/new-start. `ev/reschedule-notify->msg` for the
+  notify wire shape. Combines overrides (calendar) + rosters (booking) + the
+  message-derivation pattern. +7 tests, 272/272 green.
+- 2026-06-07 — Booking lifecycle notifications (extension). `booking-notify.sx`
+  walks the booking stream into ordered notifications classified by kind:
+  :booked / :promoted / :held / :confirmed / :released / :cancelled /
+  :waitlisted. Promotion is detected by folding the waitlist as we walk (a
+  :booking for a currently-waitlisted actor is a promotion, not a fresh
+  booking). id = occ-key/seq (stable stream seq → idempotent re-derivation, no
+  double-ping). `ev/booking-notifications`, `ev/notify-of-kind`,
+  `ev/booking-notify->msg` (notify wire shape). Connects ticketing to the
+  delivery layer. +11 tests, 265/265 green.
+- 2026-06-07 — Per-occurrence overrides / reschedule (RFC 5545 RECURRENCE-ID).
+  `ev-with-override event orig-start new-start new-duration` adds an :overrides
+  entry keyed by the occurrence's original start. `ev-expand` applies overrides
+  after EXDATE/RDATE: a targeted instance is re-timed/re-sized and the agenda
+  re-sorted; an instance moved out of the window is dropped (slot vacated);
+  override of a non-occurring start is a no-op. Used `assoc` for immutable
+  event update. +6 tests, 254/254 green.
+- 2026-06-07 — RRULE exceptions EXDATE/RDATE (extension). `ev-event-full`
+  carries :exdate/:rdate (epoch-minute starts). Raw expansion renamed
+  `ev-expand-base`; `ev-expand` now applies exceptions: RDATE adds explicit
+  in-window occurrences, EXDATE removes matching starts, duplicates de-duped,
+  EXDATE wins over RDATE and the rrule (RFC 5545). RDATE-only events (no rrule)
+  supported. Plain `ev-event` (no exception keys) unaffected. +8 tests,
+  248/248 green.
+- 2026-06-07 — Waitlist + auto-promotion (extension). When an occurrence is
+  full, `ev/waitlist!` queues actors FIFO (:waitlist/:unwaitlist events on the
+  same stream; waiting fold is independent of the seat fold since taking a seat
+  removes from the queue). `ev/waitlist` (queue), `ev/waitlist-position`,
+  `ev/leave-waitlist!`. `ev/cancel-promote!` cancels a seat and auto-promotes
+  the head of the queue to a confirmed booking when capacity opens. Idempotent
+  (:already / :already-waiting). +21 tests, 240/240 green.
+- 2026-06-07 — Federated free/busy (extension). Peers publish BUSY intervals
+  per actor (iCal free/busy model — privacy-preserving, not event details).
+  `ev/peer-with-busy`, `ev/peer-busy`; `ev/federated-busy` unions local
+  availability-db busy + trusted peers' published busy (sorted);
+  `ev/federated-free?` answers "is X free in [qs,qe)?" across instances,
+  half-open, trust-gated (untrusted peers' busy ignored; revocation immediate).
+  +10 tests, 219/219 green.
+- 2026-06-07 — **Phase 4: federation (trust-gated stub).** `federation.sx`:
+  a peer publishes a schedule (events store); `ev/federated-agenda` merges the
+  local agenda (origin :local) with every TRUSTED peer's agenda, sorted by
+  start, each occurrence tagged with :origin provenance. Trust is a peer-id set
+  re-checked per merge (revocation is immediate); untrusted peers contribute
+  nothing. `ev/peer`, `ev/trusts?`, `ev/trusted-peers`, `ev/peer-agenda`
+  (expands the peer's recurrence in-window), `ev/from-origin` (filter by
+  source). Real transport slots behind `ev/peer-agenda` unchanged. +13 tests,
+  **209/209 green — all four plan phases implemented.**
+- 2026-06-07 — Reminders + digests from the agenda. `reminders.sx` bridges
+  calendar + durable rosters to notify: `ev/occurrence-reminders` (one per
+  booked attendee, fires `lead` before start, idempotency key
+  occ-key/recipient/lead), `ev/agenda-reminders` (window-wide, sorted by
+  fire-at), `ev/due-reminders` (fire-at ≤ now — the scheduler query),
+  `ev/reminder->msg` (projects to notify's (id recipient body) shape),
+  `ev/agenda-digest` + `ev/agenda-for-p` (an actor's upcoming booked
+  occurrences). +14 tests, 196/196 green.
+- 2026-06-07 — **Phase 3 start: notification delivery flows.** `notify.sx`:
+  reminders + digests as durable `flow`s over an INJECTED transport (the host
+  `dispatch`). A flow `request`s delivery (suspend), the host sends and resumes
+  with the outcome; flow's replay log means a completed send is never re-run on
+  recovery. At-least-once + idempotent: messages carry an id; the transport
+  dedups (re-send is a no-op that still reports ok) and replay logs each
+  outcome. Retry rides suspend/resume — each attempt uses a DISTINCT tag
+  `(deliver <id> <n>)` so replay stays correct; dispatch returns (ok) /
+  (retry reason), bounded by maxn → (failed id reason). Digest delivers a batch
+  with independent per-message outcomes. Authored as Scheme flow source run via
+  `ev/notify-run` (scheme + flow substrate preloaded). +7 tests, 182/182 green.
+  Delivery core is the `delivery-on-sx` extraction seam for feed/notify.
+- 2026-06-07 — **Phase 2 complete: paid-ticket contract.** `ticket.sx` defines
+  the two wire messages between events and commerce — `checkout-request`
+  (events→commerce) and `payment-result` (commerce→events, :paid/:failed/
+  :expired) — so commerce imports the contract, not vice versa. Orchestration
+  over holds: `ev/request-ticket!` places a capacity-safe hold + emits a
+  checkout-request; `ev/settle-payment!` confirms on :paid, releases on
+  failure/expiry. Idempotent (redelivered :paid stays confirmed, redelivered
+  release is :noop); a late :paid for a vanished hold → :paid-but-no-hold
+  (refund signal), no phantom seat. occ-key+actor locate the hold so no side
+  table. +31 tests, 175/175 green. Phase 3 (notification flows) is next.
+- 2026-06-07 — Provisional holds (paid-ticket foundation). Booking stream now
+  carries :booking/:hold/:confirm/:release/:cancel; the fold tracks per-actor
+  seat STATE (:held / :confirmed). A held seat counts toward capacity, so a
+  pending payment cannot be oversold. `ev/hold!` (capacity-safe, retrying),
+  `ev/confirm!` (held→confirmed), `ev/release!` (frees a held seat only),
+  `ev/seat-state`. Seat-acquiring writes (:booking/:hold) go through
+  append-expect; seat-freeing writes (:cancel/:release) and :confirm append
+  directly (never oversell). Holds race test mirrors the booking race. +24
+  tests, 144/144 green. Next: ticket.sx contract module over holds.
+- 2026-06-07 — Wired `booking.sx` into `api.sx`: durable persist-backed booking
+  path alongside the in-memory one. `ev/book-occ!`, `ev/cancel-occ!`,
+  `ev/roster-occ`, `ev/seats-left-occ` (capacity from the scheduled event);
+  `ev/free-p?`, `ev/next-free-p`, `ev/conflicts-p` derive availability by
+  replaying persist booking streams for in-window occurrences. Capacity-safe +
+  cancellable bookings now flow through the public API. Reordered conformance
+  preloads (persist + booking before events/api). +10 tests, 120/120 green.
+- 2026-06-07 — Cancellation + seat release. Booking stream now carries
+  :booking / :cancel events; the live roster is the FOLDED replay (book adds,
+  cancel removes) so capacity reopens when a seat is freed. `ev/cancel!`
+  (retrying, append-expect), `ev/cancel-with-observed`. Edge cases: cancelling
+  an unbooked actor → :not-booked (no-op), double cancel → :not-booked,
+  cancelled actor may re-book. Capacity count is the folded roster size, not
+  the physical event count. +13 tests, 110/110 green.
+- 2026-06-07 — **Phase 2 start: capacity-safe booking.** `booking.sx`: one
+  append-only persist stream per occurrence; roster = stream replayed. Booking
+  decisions made against an OBSERVED (roster, last-seq) snapshot, committed via
+  `persist/append-expect` — append only if last-seq unchanged, else a conflict
+  value the booker retries. This makes capacity-check + append atomic at the
+  persist boundary: no overbooking, no lock. `ev/book!` (retrying),
+  `ev/book-with-observed`, `ev/roster`, `ev/seats-left`. Idempotent per actor
+  (:already). Explicit last-seat race test: two bookers on the same snapshot →
+  one :booked, one :conflict, roster never exceeds capacity; loser retry →
+  :full (or next seat when room remains). 24 tests, 97/97 green.
+- 2026-06-07 — **Phase 1 complete.** `api.sx`: immutable `store`
+  ({:events :bookings}) facade over calendar + availability. `ev/schedule`,
+  `ev/book`, `ev/agenda`, `ev/agenda-for`, `ev/free?`, `ev/next-free`,
+  `ev/conflicts`. Availability queries auto-widen the expansion window back by
+  the longest event so any overlapping occurrence is captured. 14 tests,
+  73/73 green. Phase 2 (transactional booking on persist) is next — `ev/book`
+  becomes capacity-safe via a persist append at that point.
+- 2026-06-07 — `next-free` slot search: earliest start ≥ after where
+  [s,s+duration) is free and ends ≤ horizon, else nil. Candidates are `after`
+  plus each busy-interval end (interval-packing); each probe reuses the
+  `busy_in` Datalog rule via `ev-free?`. Finds gaps between bookings, skips
+  too-short gaps, half-open at edges. +6 tests, 59/59.
+- 2026-06-07 — `availability.sx`: free/busy + conflict detection as forward-
+  chained Datalog over `occurrence`/`booking` EDB. Rules `busy(A,S,E)`,
+  `conflict(A,O1,O2)` (canonical `O1<O2`, half-open overlap `S1<E2 ∧ S2<E1`),
+  `busy_in(A,QS,QE)` for window queries. API: `ev-busy`, `ev-conflicts`,
+  `ev-has-conflict?`, `ev-free?` (transient qwindow assert/retract). Integrates
+  with calendar expansion (book expanded occurrences). 16 tests, 53/53 green.
+- 2026-06-06 — MONTHLY recurrence. `ev-days-in-month`, `ev-add-months`,
+  BYMONTHDAY (incl. negative = from month end), ordinal BYDAY (`{:ord N :wd W}`,
+  ord<0 = nth-from-last), default day-of-month (skips months too short, e.g.
+  day-31 monthly skips Feb/Apr). Refactored weekly+monthly onto a shared
+  `ev-emit-occs` per-period emitter. 37/37 green (+13).
+- 2026-06-06 — Phase 1 scaffold + calendar recurrence. `calendar.sx`: integer
+  epoch-minute datetimes, Hinnant civil<->day-number conversion, DAILY/WEEKLY
+  RRULE expansion in a bounded (start,end) window with INTERVAL, COUNT (window-
+  independent), UNTIL, BYDAY (weekly). `ev-expand-all` merges + sorts. Wired
+  conformance harness (conf + thin wrapper reusing `lib/guest/conformance.sh`),
+  scoreboard. 24/24 green. MONTHLY deferred to next commit.
 
 ## Blockers
-(loop fills this in)
+
+- None. Substrates present: `lib/datalog` (276/276), `lib/persist`, `lib/flow`
+  all exist — Phase 2/3 unblocked when reached.