calendar: add recurring events, event management, and safety rules

Add --rrule flag to send with DTSTART/BYDAY validation (RFC 5545).
Add event list (via khal) and event delete (safe single-event removal).
Document safety rules from 2026-03-25 incident: always dry-run recurring
events, never rm .ics files, space out SMTP sends.

skills/calendar/SKILL.md

@@ -33,12 +33,16 @@ All commands go through the wrapper script:
 ```bash
 SKILL_DIR=~/.openclaw/workspace/skills/calendar
 
-# Send an invite
+# Send an invite (supports recurring events via --rrule)
 $SKILL_DIR/scripts/calendar.sh send [options]
 
 # Reply to an invite
 $SKILL_DIR/scripts/calendar.sh reply [options]
 
+# Manage events
+$SKILL_DIR/scripts/calendar.sh event list [options]
+$SKILL_DIR/scripts/calendar.sh event delete [options]
+
 # Manage todos
 $SKILL_DIR/scripts/calendar.sh todo add [options]
 $SKILL_DIR/scripts/calendar.sh todo list [options]
@@ -76,6 +80,7 @@ $SKILL_DIR/scripts/calendar.sh send \
 | `--location`    | No       | Event location                                 |
 | `--description` | No       | Event description / notes                      |
 | `--organizer`   | No       | Organizer display name (defaults to `--from`)  |
+| `--rrule`       | No       | Recurrence rule (e.g. `FREQ=WEEKLY;COUNT=13;BYDAY=TU`) |
 | `--uid`         | No       | Custom event UID (auto-generated if omitted)   |
 | `--account`     | No       | Himalaya account name (if not default)         |
 | `--dry-run`     | No       | Print ICS + MIME without sending                |
@@ -101,7 +106,17 @@ $SKILL_DIR/scripts/calendar.sh send \
   --location "Zoom - https://zoom.us/j/123456" \
   --description "Weekly check-in. Agenda: updates, blockers, action items."
 
-# Dry run
+# Recurring: every Tuesday for 13 weeks (--start MUST fall on a Tuesday)
+$SKILL_DIR/scripts/calendar.sh send \
+  --to "alice@example.com" \
+  --subject "Allergy Shot (Tue)" \
+  --summary "Allergy Shot (Tue)" \
+  --start "2026-03-31T14:30:00" \
+  --end "2026-03-31T15:00:00" \
+  --location "11965 Venice Blvd. #300, LA" \
+  --rrule "FREQ=WEEKLY;COUNT=13;BYDAY=TU"
+
+# Dry run (always use for recurring events to verify)
 $SKILL_DIR/scripts/calendar.sh send \
   --to "test@example.com" \
   --subject "Test" \
@@ -111,6 +126,52 @@ $SKILL_DIR/scripts/calendar.sh send \
   --dry-run
 ```
 
+### Recurring Events (--rrule)
+
+The `--rrule` flag accepts an RFC 5545 RRULE string. Common patterns:
+
+| Pattern | RRULE |
+|---------|-------|
+| Weekly on Tue, 13 weeks | `FREQ=WEEKLY;COUNT=13;BYDAY=TU` |
+| Weekly on Mon/Wed/Fri, until date | `FREQ=WEEKLY;UNTIL=20260630T000000Z;BYDAY=MO,WE,FR` |
+| Every 2 weeks on Thu | `FREQ=WEEKLY;INTERVAL=2;BYDAY=TH` |
+| Monthly on the 15th, 6 times | `FREQ=MONTHLY;COUNT=6;BYMONTHDAY=15` |
+| Daily for 5 days | `FREQ=DAILY;COUNT=5` |
+
+**Critical rule**: For `FREQ=WEEKLY` with a single `BYDAY`, the `--start` date **must fall on that day of the week**. The tool validates this and will reject mismatches. RFC 5545 says mismatched DTSTART/BYDAY produces undefined behavior.
+
+**Best practice**: Always `--dry-run` first for recurring events to verify the generated ICS.
+
+---
+
+## Managing Events
+
+```bash
+# List upcoming events (next 90 days)
+$SKILL_DIR/scripts/calendar.sh event list
+
+# Search events by text
+$SKILL_DIR/scripts/calendar.sh event list --search "Allergy"
+
+# List with UIDs (for deletion)
+$SKILL_DIR/scripts/calendar.sh event list --format "{uid} {title}"
+
+# Custom date range
+$SKILL_DIR/scripts/calendar.sh event list --range-start "2026-04-01" --range-end "2026-04-30"
+
+# Delete by UID
+$SKILL_DIR/scripts/calendar.sh event delete --uid "abc123@openclaw"
+
+# Delete by summary match
+$SKILL_DIR/scripts/calendar.sh event delete --match "Allergy Shot (Tue)"
+```
+
+### Event Delete Safety
+
+- Deletes only ONE event at a time. If multiple events match, it lists them and exits.
+- **NEVER use `rm` on calendar .ics files directly.** Always use `event delete`.
+- After deleting, verify with `event list` or `khal list`.
+
 ---
 
 ## Replying to Invites