events: end-to-end delivery pipeline (derivation -> notify flow) + 8 tests

ev/deliver-messages bridges SX notification messages to the Scheme notify
flow: each (id recipient body) is serialized to s-expr text, spliced as quoted
data into the digest-flow program, delivered over an injected transport, and
results unboxed. Integration suite drives all three derivations (reminders /
booking-notify / reschedule) through delivery end to end; empty batch guarded
(empty digest completes without suspending). 303/303 green.

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

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` → **295/295** (Phases 1-4 + 8 ext: fed f/b, waitlist, EXDATE/RDATE, overrides, booking/reschedule-notify, fed transport, timezones+DST)
+`bash lib/events/conformance.sh` → **303/303** (Phases 1-4 + 9 ext: fed f/b, waitlist, EXDATE/RDATE, overrides, booking/reschedule-notify, fed transport, timezones+DST, e2e delivery pipeline)
 
 ## Ground rules
 
@@ -74,6 +74,8 @@ lib/events/api.sx ── (events/schedule) (events/book) (events/agenda) ──
 - [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)
+- [x] end-to-end pipeline: derive (reminders/booking/reschedule) → deliver via
+  the notify flow (`ev/deliver-messages`, SX→Scheme bridge)
 - [ ] NOTE: shared with `feed/notify` — candidate for later extraction to a
   `delivery-on-sx` once a second consumer is real. **Delivery core
   (request→dispatch→resume, idempotent, bounded retry) is the extraction seam.**
@@ -86,6 +88,16 @@ lib/events/api.sx ── (events/schedule) (events/book) (events/agenda) ──
 
 ## Progress log
 
+- 2026-06-07 — End-to-end delivery pipeline (closes the derivation↔delivery
+  gap). `ev/deliver-messages` bridges SX notification messages to the Scheme
+  notify flow: each (id recipient body) is `serialize`d to s-expression text,
+  spliced as quoted data into the digest-flow program, delivered over an
+  injected transport-src, and results unboxed ({:scm-string}→str). New
+  integration suite drives all three derivations through delivery: reminders →
+  delivered (ids = idempotency keys), transient-fail transport → failed,
+  waitlist-promotion notification → delivered, reschedule notice → delivered,
+  empty batch → empty (guarded: an empty digest completes without suspending).
+  +8 tests, 303/303 green.
 - 2026-06-07 — Timezone + DST support (user request). `timezone.sx`: a tz maps
   wall-clock LOCAL ↔ absolute UTC (offset = local-utc). :fixed (constant) and
   :dst (std/dst offsets + two UTC transition rules, e.g. EU last-Sun-Mar/Oct