feat: add NIP-52 Nostr publish + sync of calendar events

Approved events are mirrored to Nostr as NIP-52 calendar events (kind
31922) signed by the wallet owner's pubkey, and incoming kind 31922/31923
events from subscribed relays are synced into the local DB so events
created on other LNbits instances or Nostr clients show up locally.

- m009 stores nostr_event_id + nostr_event_created_at on each event
  (used for replaceable updates and NIP-09 deletes); m011 adds location
  + JSON-encoded categories list (NIP-52 location/`t` tags).
- models: Event/PublicEvent/CreateEvent gain location, categories,
  nostr_event_id, nostr_event_created_at; parse_categories validator
  decodes the JSON column on read.
- nostr/{event,nostr_client}.py: Schnorr signing, websocket relay client,
  and a NostrEvent model (publish-only and subscribe variants).
- nostr_publisher.py: build/sign NIP-52 kind 31922 events and NIP-09
  delete events; publish via the relay client.
- nostr_sync.py: subscribe to kinds 31922/31923, dedupe by nostr_event_id
  / d-tag, upsert Events; auto-approves discovered Nostr events since
  they're already public.
- nostr_hooks.py: thin bridge that views_api handlers call to publish
  or delete a NIP-52 event for a given local event. Lives in its own
  module to keep `from . import nostr_client` out of the view layer
  and avoid the views_api -> publisher import cycle.
- views_api: hooks publish_or_delete_nostr_event into create-on-approved,
  update-when-already-published, cancel (delete), delete (delete), and
  approve (publish).
- __init__.py: 3-task lifespan — wait_for_paid_invoices (upstream),
  NostrClient bootstrap, and the NIP-52 sync loop. Module-level
  nostr_client global is set by the bootstrap and read dynamically by
  publish_or_delete_nostr_event so the import order works regardless of
  whether nostrclient is up at startup.

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

nostr/nostr_client.py

@@ -0,0 +1,142 @@
+"""
+Bidirectional Nostr client for the events extension.
+
+Connects to the nostrclient extension's internal WebSocket to publish
+and subscribe to NIP-52 calendar events. Based on nostrmarket's
+NostrClient pattern.
+"""
+
+import asyncio
+import json
+from asyncio import Queue
+from collections import OrderedDict
+
+from lnbits.helpers import encrypt_internal_message, urlsafe_short_hash
+from lnbits.settings import settings
+from loguru import logger
+from websocket import WebSocketApp
+
+from .event import NostrEvent
+
+MAX_SEEN_EVENTS = 500
+
+
+class NostrClient:
+    def __init__(self):
+        self.receive_event_queue: Queue = Queue()
+        self.send_req_queue: Queue = Queue()
+        self.ws: WebSocketApp | None = None
+        self.subscription_id = "events-" + urlsafe_short_hash()[:32]
+        self.running = False
+        self._seen_events: OrderedDict[str, None] = OrderedDict()
+
+    @property
+    def is_websocket_connected(self):
+        if not self.ws:
+            return False
+        return self.ws.keep_running
+
+    async def connect(self) -> WebSocketApp:
+        relay_endpoint = encrypt_internal_message("relay", urlsafe=True)
+        ws_url = (
+            f"ws://localhost:{settings.port}"
+            f"/nostrclient/api/v1/{relay_endpoint}"
+        )
+
+        logger.info("[EVENTS] Connecting to nostrclient WebSocket...")
+
+        def on_open(_):
+            logger.info("[EVENTS] Connected to nostrclient WebSocket")
+
+        def on_message(_, message):
+            try:
+                self.receive_event_queue.put_nowait(message)
+            except Exception as e:
+                logger.error(f"[EVENTS] Failed to queue message: {e}")
+
+        def on_error(_, error):
+            logger.warning(f"[EVENTS] WebSocket error: {error}")
+
+        def on_close(_, status_code, message):
+            logger.warning(
+                f"[EVENTS] WebSocket closed: {status_code} {message}"
+            )
+            self.receive_event_queue.put_nowait(
+                ValueError("WebSocket closed")
+            )
+
+        ws = WebSocketApp(
+            ws_url,
+            on_message=on_message,
+            on_open=on_open,
+            on_close=on_close,
+            on_error=on_error,
+        )
+
+        from threading import Thread
+
+        wst = Thread(target=ws.run_forever)
+        wst.daemon = True
+        wst.start()
+
+        return ws
+
+    async def run_forever(self):
+        self.running = True
+        while self.running:
+            try:
+                if not self.is_websocket_connected:
+                    self.ws = await self.connect()
+                    await asyncio.sleep(5)
+
+                req = await self.send_req_queue.get()
+                assert self.ws
+                self.ws.send(json.dumps(req))
+            except Exception as ex:
+                logger.warning(f"[EVENTS] NostrClient error: {ex}")
+                await asyncio.sleep(60)
+
+    def is_duplicate_event(self, event_id: str) -> bool:
+        """Check if an event has been seen recently."""
+        if event_id in self._seen_events:
+            return True
+        self._seen_events[event_id] = None
+        if len(self._seen_events) > MAX_SEEN_EVENTS:
+            self._seen_events.popitem(last=False)
+        return False
+
+    async def get_event(self):
+        """Get next event from the receive queue."""
+        value = await self.receive_event_queue.get()
+        if isinstance(value, ValueError):
+            raise value
+        return value
+
+    async def publish_nostr_event(self, e: NostrEvent):
+        await self.send_req_queue.put(["EVENT", e.dict()])
+
+    async def subscribe(self, filters: list[dict]):
+        """Subscribe to events matching the given filters."""
+        self.subscription_id = "events-" + urlsafe_short_hash()[:32]
+        await self.send_req_queue.put(
+            ["REQ", self.subscription_id, *filters]
+        )
+        logger.info(
+            f"[EVENTS] Subscribed to NIP-52 events "
+            f"(sub: {self.subscription_id[:20]}...)"
+        )
+
+    async def unsubscribe(self):
+        """Unsubscribe from current subscription."""
+        await self.send_req_queue.put(["CLOSE", self.subscription_id])
+
+    async def stop(self):
+        await self.unsubscribe()
+        self.running = False
+        await asyncio.sleep(2)
+        if self.ws:
+            try:
+                self.ws.close()
+            except Exception:
+                pass
+            self.ws = None