feat: support optional start/end time on events

event_start_date / event_end_date now accept either YYYY-MM-DD (date-only)
or YYYY-MM-DDTHH:MM (ISO datetime). The NIP-52 publisher switches kind
on the "T" delimiter: kind 31922 (date-based, YYYY-MM-DD start/end) when
absent, kind 31923 (time-based, unix-timestamp start/end + day-granularity
D tags) when present. Delete events match the original publish kind.

Closing-date parsing accepts both formats. The LNbits admin form gains
optional HH:MM inputs alongside each date picker; they fold into the
wire-format string on submit and split back on edit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nostr_publisher.py

@@ -1,14 +1,17 @@
 """
 NIP-52 calendar event publishing for the events extension.
 
-Builds kind 31922 (date-based) calendar events from the Event model,
-signs them with the event creator's Account keypair, and publishes
-via the NostrClient to nostrclient relays.
+Builds NIP-52 calendar events from the Event model, signs them with the
+creator's Account keypair, and publishes via the NostrClient.
+
+Kind 31922 is used for date-only events; kind 31923 (time-based) is used
+when event_start_date / event_end_date include a time component.
 
 Reference: https://github.com/nostr-protocol/nips/blob/master/52.md
 """
 
 import time
+from datetime import datetime, timezone
 
 import coincurve
 from loguru import logger
@@ -17,26 +20,60 @@ from .models import Event
 from .nostr.event import NostrEvent
 
 
+def _has_time(value: str | None) -> bool:
+    """ISO 8601 datetime strings contain a 'T' between date and time."""
+    return value is not None and "T" in value
+
+
+def _to_unix(value: str) -> int:
+    """Parse ISO 8601 datetime (assume UTC if naive) to unix seconds."""
+    dt = datetime.fromisoformat(value)
+    if dt.tzinfo is None:
+        dt = dt.replace(tzinfo=timezone.utc)
+    return int(dt.timestamp())
+
+
 def build_nip52_event(event: Event, pubkey: str) -> NostrEvent:
     """
-    Convert an Event model to a NIP-52 kind 31922 (date-based) calendar event.
+    Convert an Event model to a NIP-52 calendar event.
 
-    Tags:
-      d       - event.id (addressable identifier)
+    Time-based (kind 31923) if event_start_date carries an HH:MM, otherwise
+    date-based (kind 31922). Tags:
+      d       - event.id
       title   - event.name
-      start   - event.event_start_date (ISO date string)
-      end     - event.event_end_date (optional)
-      image   - event.banner (optional)
-    Content:  event.info (description)
+      start   - unix timestamp (31923) or YYYY-MM-DD (31922)
+      end     - same encoding (optional)
+      image, location, t (categories) - optional
+    Content:  event.info
     """
+    time_based = _has_time(event.event_start_date)
+    kind = 31923 if time_based else 31922
+    start_value = (
+        str(_to_unix(event.event_start_date)) if time_based else event.event_start_date
+    )
+
     tags = [
         ["d", event.id],
         ["title", event.name],
-        ["start", event.event_start_date],
+        ["start", start_value],
     ]
 
+    end_unix: int | None = None
     if event.event_end_date:
-        tags.append(["end", event.event_end_date])
+        end_value = (
+            str(_to_unix(event.event_end_date)) if time_based else event.event_end_date
+        )
+        tags.append(["end", end_value])
+        if time_based:
+            end_unix = _to_unix(event.event_end_date)
+
+    if time_based:
+        start_unix = _to_unix(event.event_start_date)
+        start_day = start_unix // 86400
+        end_day = (end_unix // 86400) if end_unix is not None else start_day
+        for day in range(start_day, end_day + 1):
+            tags.append(["D", str(day)])
+
     if event.banner:
         tags.append(["image", event.banner])
     if event.location:
@@ -47,7 +84,7 @@ def build_nip52_event(event: Event, pubkey: str) -> NostrEvent:
     nostr_event = NostrEvent(
         pubkey=pubkey,
         created_at=int(time.time()),
-        kind=31922,
+        kind=kind,
         tags=tags,
         content=event.info or "",
     )
@@ -59,15 +96,17 @@ def build_nip52_delete_event(event: Event, pubkey: str) -> NostrEvent:
     """
     Build a kind 5 delete event for a published NIP-52 calendar event.
 
-    Uses an 'a' tag to reference the parameterized replaceable event
-    (kind 31922) per NIP-09.
+    Uses an 'a' tag to reference the parameterized replaceable event per
+    NIP-09. The referenced kind must match what we published — 31923 for
+    time-based events, 31922 for date-only.
     """
+    referenced_kind = 31923 if _has_time(event.event_start_date) else 31922
     nostr_event = NostrEvent(
         pubkey=pubkey,
         created_at=int(time.time()),
         kind=5,
         tags=[
-            ["a", f"31922:{pubkey}:{event.id}"],
+            ["a", f"{referenced_kind}:{pubkey}:{event.id}"],
         ],
         content="Event canceled",
     )