fix(webhooks): wire receiver to vector sync queue and fix registered URI

The /webhooks/nextcloud endpoint was a no-op stub that logged the
payload and returned 200 OK; webhook deletions never reached Qdrant.
Compounding that, _get_webhook_uri() registered the docker-compose
internal hostname (http://mcp:8000) with Nextcloud whenever
/.dockerenv existed — including ECS Fargate — so cloud deployments
were registering a URL NC could not resolve.

- New vector/webhook_parser.py extracts a DocumentTask from
  NodeCreatedEvent / NodeWrittenEvent / BeforeNodeDeletedEvent
  payloads scoped to */files/Notes/*.md (matching the registered
  preset filters).
- New vector/webhook_receiver.py pushes that task onto the same
  send-stream the scanner uses (app.state.document_send_stream),
  with 503 when sync is not running so NC retries delivery.
- _get_webhook_uri() now prefers NEXTCLOUD_MCP_SERVER_URL over the
  /.dockerenv branch, so the explicit public URL set on cloud tasks
  wins; docker-compose dev still falls back to the internal name when
  no public URL is configured.

Calendar / Tables event parsing is intentionally out of scope here.

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

nextcloud_mcp_server/vector/webhook_parser.py

@@ -0,0 +1,86 @@
+"""Parse Nextcloud webhook payloads into DocumentTask objects.
+
+Maps Nextcloud webhook events to vector-sync DocumentTasks. The handler at
+``/webhooks/nextcloud`` calls :func:`extract_document_task` and forwards any
+non-None result to the same processor send-stream the scanner uses.
+
+Currently scoped to file (note) events. Calendar / Tables events fall through
+to ``None`` for now; those parsers can be added in follow-up changes.
+
+See ADR-010 for the design and ``webhook-testing-findings.md`` for real
+captured payloads.
+"""
+
+import logging
+import re
+
+from nextcloud_mcp_server.vector.scanner import DocumentTask
+
+logger = logging.getLogger(__name__)
+
+_FILE_EVENT_CREATED = "OCP\\Files\\Events\\Node\\NodeCreatedEvent"
+_FILE_EVENT_WRITTEN = "OCP\\Files\\Events\\Node\\NodeWrittenEvent"
+_FILE_EVENT_BEFORE_DELETED = "OCP\\Files\\Events\\Node\\BeforeNodeDeletedEvent"
+
+# Matches paths inside any user's Notes folder ending in .md, e.g.
+# "/admin/files/Notes/Sub/Note.md" or "/alice/files/Notes/foo.md".
+_NOTES_PATH_RE = re.compile(r"^/[^/]+/files/Notes/.+\.md$")
+
+
+def extract_document_task(payload: dict) -> DocumentTask | None:
+    """Convert a Nextcloud webhook payload into a DocumentTask.
+
+    Returns None for any event we don't (yet) handle, or any event whose
+    target isn't a markdown file under a user's Notes folder. Callers should
+    treat None as "ignored" — not an error.
+    """
+    try:
+        event = payload["event"]
+        event_class = event["class"]
+        user_id = payload["user"]["uid"]
+    except (KeyError, TypeError):
+        logger.debug("Webhook payload missing user/event/class fields")
+        return None
+
+    if event_class in (
+        _FILE_EVENT_CREATED,
+        _FILE_EVENT_WRITTEN,
+        _FILE_EVENT_BEFORE_DELETED,
+    ):
+        return _parse_file_event(event_class, event, user_id, payload.get("time", 0))
+
+    logger.debug("Ignoring webhook for unsupported event: %s", event_class)
+    return None
+
+
+def _parse_file_event(
+    event_class: str, event: dict, user_id: str, time: int
+) -> DocumentTask | None:
+    node = event.get("node") or {}
+    path = node.get("path", "")
+    node_id = node.get("id")
+
+    if not _NOTES_PATH_RE.match(path):
+        # Not a note file — could be a parent folder, an unrelated file, etc.
+        return None
+
+    if node_id is None:
+        # BeforeNodeDeletedEvent should still carry node.id; if it doesn't
+        # we can't address the Qdrant points to delete. Skip rather than
+        # guess — the polling scanner will catch up via its grace period.
+        logger.warning(
+            "Webhook %s for note %s missing node.id; falling back to scanner",
+            event_class,
+            path,
+        )
+        return None
+
+    operation = "delete" if event_class == _FILE_EVENT_BEFORE_DELETED else "index"
+
+    return DocumentTask(
+        user_id=user_id,
+        doc_id=str(node_id),
+        doc_type="note",
+        operation=operation,
+        modified_at=int(time),
+    )