events: sync scoreboard.md to 391/391

Companion to b2578139 — the markdown scoreboard render.

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

lib/events/scoreboard.json

@@ -1,12 +1,12 @@
 {
   "lang": "events",
-  "total_passed": 376,
+  "total_passed": 391,
   "total_failed": 0,
-  "total": 376,
+  "total": 391,
   "suites": [
     {"name":"calendar","passed":51,"failed":0,"total":51},
-    {"name":"timezone","passed":17,"failed":0,"total":17},
-    {"name":"ical","passed":56,"failed":0,"total":56},
+    {"name":"timezone","passed":25,"failed":0,"total":25},
+    {"name":"ical","passed":63,"failed":0,"total":63},
     {"name":"availability","passed":22,"failed":0,"total":22},
     {"name":"api","passed":41,"failed":0,"total":41},
     {"name":"booking","passed":82,"failed":0,"total":82},
@@ -17,5 +17,5 @@
     {"name":"federation","passed":29,"failed":0,"total":29},
     {"name":"integration","passed":8,"failed":0,"total":8}
   ],
-  "generated": "2026-06-07T20:02:48+00:00"
+  "generated": "2026-06-10T22:03:34+00:00"
 }

lib/events/scoreboard.md

@@ -1,12 +1,12 @@
 # events scoreboard
 
-**376 / 376 passing** (0 failure(s)).
+**391 / 391 passing** (0 failure(s)).
 
 | Suite | Passed | Total | Status |
 |-------|--------|-------|--------|
 | calendar | 51 | 51 | ok |
-| timezone | 17 | 17 | ok |
-| ical | 56 | 56 | ok |
+| timezone | 25 | 25 | ok |
+| ical | 63 | 63 | ok |
 | availability | 22 | 22 | ok |
 | api | 41 | 41 | ok |
 | booking | 82 | 82 | ok |

lib/events/tests/ical.sx

@@ -335,6 +335,17 @@
         (do
           (ev-ic-check! "Paris DAYLIGHT goes to +0200 (CEST)" (ev-ic-find vtz "TZOFFSETTO:+0200") "TZOFFSETTO:+0200")
           (ev-ic-check! "Paris STANDARD goes to +0100 (CET)" (ev-ic-find vtz "TZOFFSETTO:+0100") "TZOFFSETTO:+0100")))
+      ;; southern hemisphere exports a valid VTIMEZONE too: reversed offsets,
+      ;; first-Sunday rules, and the -480 rule time folds back to local 02:00/03:00
+      (let
+        ((vtz (ev-ical-vtimezone ev-tz-sydney)))
+        (do
+          (ev-ic-check! "Sydney VTIMEZONE names the zone" (ev-ic-find vtz "TZID") "TZID:Australia/Sydney")
+          (ev-ic-check! "Sydney DAYLIGHT goes to +1100 (AEDT)" (ev-ic-find vtz "TZOFFSETTO:+1100") "TZOFFSETTO:+1100")
+          (ev-ic-check! "Sydney STANDARD goes to +1000 (AEST)" (ev-ic-find vtz "TZOFFSETTO:+1000") "TZOFFSETTO:+1000")
+          (ev-ic-check! "Sydney DAYLIGHT rule is first Sunday of October" (ev-ic-find vtz "RRULE:FREQ=YEARLY;BYMONTH=10") "RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=1SU")
+          (ev-ic-check! "Sydney STANDARD rule is first Sunday of April" (ev-ic-find vtz "RRULE:FREQ=YEARLY;BYMONTH=4") "RRULE:FREQ=YEARLY;BYMONTH=4;BYDAY=1SU")
+          (ev-ic-check! "Sydney DAYLIGHT begins 02:00 local (AEST std, -480 folded)" (ev-ic-find vtz "DTSTART") "DTSTART:19701004T020000")))
 
       ;; ---- VCALENDAR carries one VTIMEZONE per distinct zone ----
       (let
@@ -371,7 +382,13 @@
         (get
           (ev/ical-lines->event (ev/event->ical-lines (ev-event-tz (quote a) (ev-dt 2026 7 15 18 0) 60 nil 1 ev-tz-london)))
           :dtstart)
-        (ev-dt 2026 7 15 18 0)))))
+        (ev-dt 2026 7 15 18 0))
+      (ev-ic-check!
+        "import parses a southern-zone DTSTART;TZID local time"
+        (get
+          (ev/ical-lines->event (ev/event->ical-lines (ev-event-tz (quote a) (ev-dt 2026 1 15 18 0) 60 nil 1 ev-tz-sydney)))
+          :dtstart)
+        (ev-dt 2026 1 15 18 0)))))
 
 (define
   ev-ical-tests-run!

lib/events/tests/timezone.sx

@@ -76,6 +76,58 @@
           ev-tz-paris
           (ev-dt 2026 7 15 12 0))
         120)
+      ;; ---- southern hemisphere (reversed seasons) ----
+      (ev-tz-check!
+        "Sydney January offset is 660 (AEDT, summer DST)"
+        (ev-tz-offset
+          ev-tz-sydney
+          (ev-dt 2026 1 15 12 0))
+        660)
+      (ev-tz-check!
+        "Sydney July offset is 600 (AEST, winter std)"
+        (ev-tz-offset
+          ev-tz-sydney
+          (ev-dt 2026 7 15 12 0))
+        600)
+      (ev-tz-check!
+        "Sydney DST starts first Sunday of October"
+        (ev-dt->civil
+          (+ (ev-tz-transition 2026 (get ev-tz-sydney :dst-start)) 480))
+        (list 2026 10 4))
+      (ev-tz-check!
+        "Sydney DST ends first Sunday of April"
+        (ev-dt->civil
+          (+ (ev-tz-transition 2026 (get ev-tz-sydney :dst-end)) 480))
+        (list 2026 4 5))
+      (ev-tz-check!
+        "09:00 Sydney in summer (AEDT) is previous-day 22:00 UTC"
+        (ev-tz-local->utc
+          ev-tz-sydney
+          (ev-dt 2026 1 15 9 0))
+        (ev-dt 2026 1 14 22 0))
+      (ev-tz-check!
+        "09:00 Sydney in winter (AEST) is previous-day 23:00 UTC"
+        (ev-tz-local->utc
+          ev-tz-sydney
+          (ev-dt 2026 7 15 9 0))
+        (ev-dt 2026 7 14 23 0))
+      (let
+        ((au (ev-event-tz (quote au) (ev-dt 2026 4 3 9 0) 60 {:freq :daily :count 5} 8 ev-tz-sydney)))
+        (let
+          ((occs (ev-expand au (ev-date 2026 3 25) (ev-date 2026 4 12))))
+          (do
+            (ev-tz-check!
+              "Sydney daily occurrences shift in UTC across the autumn DST end"
+              (map (fn (o) (ev-dt-tod (get o :start))) occs)
+              (list 1320 1320 1380 1380 1380))
+            (ev-tz-check!
+              "but every Sydney occurrence stays 09:00 local wall-clock"
+              (map
+                (fn
+                  (o)
+                  (first (rest (ev-tz-local-of ev-tz-sydney (get o :start)))))
+                occs)
+              (list 540 540 540 540 540)))))
       (ev-tz-check!
         "DST starts last Sunday of March"
         (ev-dt->civil

lib/events/timezone.sx

@@ -13,8 +13,11 @@
 ;;   :fixed  — a constant offset.
 ;;   :dst    — std/dst offsets + two transition rules. Transitions are given in
 ;;             UTC (EU zones all switch at 01:00 UTC), so the offset at any UTC
-;;             instant is a direct range check; no recursion. Northern-hemisphere
-;;             ordering (dst-start < dst-end within a year) is assumed.
+;;             instant is a direct range check; no recursion. Both hemispheres
+;;             are supported: northern zones have dst-start < dst-end (DST is the
+;;             interval [start, end)); southern zones have dst-start > dst-end
+;;             (DST wraps the year boundary), detected by comparing the two
+;;             transitions — see ev-tz-offset.
 ;;
 ;; Requires calendar.sx (ev-dt, ev-days-from-civil, ev-civil-from-days,
 ;; ev-civ-y, ev-floor-div, ev-resolve-nth-weekday).
@@ -58,10 +61,20 @@
           (let
             ((start (ev-tz-transition year (get tz :dst-start)))
               (end (ev-tz-transition year (get tz :dst-end))))
+            ;; Northern hemisphere: dst-start < dst-end, DST is the closed-open
+            ;; interval [start, end). Southern hemisphere: dst-start > dst-end
+            ;; (DST begins in spring ~Oct and ends ~Apr), so within a calendar
+            ;; year DST wraps the boundary — active OUTSIDE [end, start).
             (if
-              (and (>= utc-dt start) (< utc-dt end))
-              (get tz :dst-offset)
-              (get tz :std-offset)))))
+              (< start end)
+              (if
+                (and (>= utc-dt start) (< utc-dt end))
+                (get tz :dst-offset)
+                (get tz :std-offset))
+              (if
+                (or (>= utc-dt start) (< utc-dt end))
+                (get tz :dst-offset)
+                (get tz :std-offset))))))
       (else 0))))
 
 ;; UTC instant -> local wall-clock.
@@ -98,6 +111,19 @@
     120
     (ev-tz-rule 3 -1 6 60)
     (ev-tz-rule 10 -1 6 60)))
+;; Southern hemisphere: AEST +600 (std, winter), AEDT +660 (dst, summer). DST
+;; begins 02:00 AEST first Sunday October and ends 03:00 AEDT first Sunday April
+;; — both 16:00 UTC the preceding Saturday, i.e. -480 minutes from the Sunday in
+;; the rule (the model adds rule :time to the resolved weekday's UTC midnight).
+;; dst-start (Oct) > dst-end (Apr), so ev-tz-offset takes the wrap-the-year path.
+(define
+  ev-tz-sydney
+  (ev-tz-dst
+    "Australia/Sydney"
+    600
+    660
+    (ev-tz-rule 10 1 6 -480)
+    (ev-tz-rule 4 1 6 -480)))
 
 ;; ---- tz-aware event expansion ----
 

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` → **376/376** (Phases 1-4 + 13 ext + tz iCal export via TZID + VTIMEZONE)
+`bash lib/events/conformance.sh` → **391/391** (Phases 1-4 + 14 ext + tz iCal export via TZID + VTIMEZONE + southern-hemisphere DST incl. iCal round-trip)
 
 ## Ground rules
 
@@ -88,6 +88,26 @@ lib/events/api.sx ── (events/schedule) (events/book) (events/agenda) ──
 
 ## Progress log
 
+- 2026-06-10 — Harden southern-hemisphere DST: explicit iCal coverage for the
+  previous commit's unverified claim that "southern zones round-trip through
+  iCal unchanged". Added a Sydney VTIMEZONE export block (TZID:Australia/Sydney,
+  DAYLIGHT→+1100/STANDARD→+1000, first-Sunday rules BYMONTH=10/4 BYDAY=1SU, and
+  DAYLIGHT DTSTART:19701004T020000 — proving the −480 rule time folds back to
+  local 02:00 AEST) and a southern-zone DTSTART;TZID export→import round-trip.
+  +7 tests (ical 63). 391/391 green.
+- 2026-06-10 — Southern-hemisphere DST. The `:dst` zone model assumed northern
+  ordering (dst-start < dst-end, DST = [start, end)); southern zones (DST begins
+  ~Oct, ends ~Apr) have dst-start > dst-end and so silently never entered DST —
+  `ev-tz-offset` returned std year-round. Fixed by detecting the ordering: when
+  start < end DST is the interval [start, end); when start > end DST wraps the
+  year boundary (active when `utc ≥ start OR utc < end`). Added predefined
+  `ev-tz-sydney` (AEST +600 / AEDT +660; transitions 02:00 AEST first-Sun-Oct
+  and 03:00 AEDT first-Sun-Apr, both 16:00 UTC the prior Saturday → rule time
+  −480). VTIMEZONE export already rule-agnostic, so southern zones round-trip
+  too (the −480 folds the from-offset back to the correct local 02:00/03:00).
+  +8 tests (timezone 25): summer/winter offsets, both transition dates,
+  local→utc both seasons, and a daily expansion crossing the autumn DST-end that
+  shifts in UTC (1320·1320·1380·1380·1380) yet stays 09:00 local. 384/384 green.
 - 2026-06-07 — VTIMEZONE iCal export (supersedes the UTC-Z tz fix — full DST
   fidelity). A tz event now exports DTSTART;TZID=<name>:<local> (+ EXDATE/RDATE
   in the same TZID-local form; UNTIL stays UTC per RFC), and the VCALENDAR emits