chore: sync GovOPlaN module split state

src/govoplan_calendar/backend/caldav.py

@@ -21,6 +21,10 @@ class CalDAVPreconditionFailed(CalDAVError):
     pass
 
 
+class CalDAVNotFound(CalDAVError):
+    pass
+
+
 class CalDAVTransport(Protocol):
     def __call__(self, method: str, url: str, headers: Mapping[str, str], body: bytes | None, timeout: int) -> tuple[int, Mapping[str, str], bytes]:
         ...
@@ -48,6 +52,29 @@ class CalDAVWriteResult:
     status: int = 0
 
 
+@dataclass(frozen=True, slots=True)
+class CalDAVDiscoveryCalendar:
+    collection_url: str
+    href: str
+    display_name: str | None = None
+    color: str | None = None
+    ctag: str | None = None
+    sync_token: str | None = None
+
+
+@dataclass(frozen=True, slots=True)
+class _DAVDiscoveryResponse:
+    href: str
+    display_name: str | None = None
+    color: str | None = None
+    ctag: str | None = None
+    sync_token: str | None = None
+    is_calendar: bool = False
+    principal_hrefs: tuple[str, ...] = ()
+    calendar_home_set_hrefs: tuple[str, ...] = ()
+    supported_components: tuple[str, ...] = ()
+
+
 class CalDAVClient:
     def __init__(
         self,
@@ -78,6 +105,96 @@ class CalDAVClient:
         payload = self.request("PROPFIND", self.collection_url, body=body, depth="0", expected={207})
         return parse_multistatus(payload)
 
+    def discover_calendars(self) -> list[CalDAVDiscoveryCalendar]:
+        start_url = self.collection_url
+        calendars: dict[str, CalDAVDiscoveryCalendar] = {}
+        home_urls: list[str] = []
+        principal_urls: list[str] = []
+        visited_urls: set[tuple[str, str]] = set()
+        errors: list[str] = []
+
+        def add_home_href(base_url: str, href: str) -> None:
+            url = ensure_collection_url(absolute_dav_url(base_url, href))
+            if url not in home_urls:
+                home_urls.append(url)
+
+        def add_principal_href(base_url: str, href: str) -> None:
+            url = ensure_collection_url(absolute_dav_url(base_url, href))
+            if url not in principal_urls:
+                principal_urls.append(url)
+
+        def add_calendar(base_url: str, response: _DAVDiscoveryResponse) -> None:
+            if not response.is_calendar:
+                return
+            if response.supported_components and "VEVENT" not in response.supported_components:
+                return
+            url = ensure_collection_url(absolute_dav_url(base_url, response.href or base_url))
+            calendars[url] = CalDAVDiscoveryCalendar(
+                collection_url=url,
+                href=response.href,
+                display_name=response.display_name,
+                color=response.color,
+                ctag=response.ctag,
+                sync_token=response.sync_token,
+            )
+
+        def propfind(url: str, depth: str) -> list[_DAVDiscoveryResponse]:
+            key = (url, depth)
+            if key in visited_urls:
+                return []
+            visited_urls.add(key)
+            return self.propfind_discovery(url, depth=depth)
+
+        try:
+            for response in propfind(start_url, "0"):
+                add_calendar(start_url, response)
+                for href in response.calendar_home_set_hrefs:
+                    add_home_href(start_url, href)
+                for href in response.principal_hrefs:
+                    add_principal_href(start_url, href)
+        except CalDAVError as exc:
+            errors.append(str(exc))
+
+        for principal_url in principal_urls[:6]:
+            try:
+                for response in propfind(principal_url, "0"):
+                    for href in response.calendar_home_set_hrefs:
+                        add_home_href(principal_url, href)
+            except CalDAVError as exc:
+                errors.append(str(exc))
+
+        if not home_urls:
+            home_urls.append(start_url)
+
+        for home_url in home_urls:
+            try:
+                for response in propfind(home_url, "1"):
+                    add_calendar(home_url, response)
+            except CalDAVError as exc:
+                errors.append(str(exc))
+
+        if not calendars and errors:
+            raise CalDAVError(f"CalDAV discovery did not find any calendar collections: {errors[0]}")
+        return sorted(calendars.values(), key=lambda item: ((item.display_name or item.collection_url).lower(), item.collection_url))
+
+    def propfind_discovery(self, url: str, *, depth: str) -> list[_DAVDiscoveryResponse]:
+        body = b"""<?xml version="1.0" encoding="utf-8"?>
+<D:propfind xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:CS="http://calendarserver.org/ns/" xmlns:ICAL="http://apple.com/ns/ical/">
+  <D:prop>
+    <D:displayname/>
+    <D:current-user-principal/>
+    <D:principal-URL/>
+    <D:resourcetype/>
+    <D:sync-token/>
+    <C:calendar-home-set/>
+    <C:supported-calendar-component-set/>
+    <CS:getctag/>
+    <ICAL:calendar-color/>
+  </D:prop>
+</D:propfind>"""
+        payload = self.request("PROPFIND", ensure_collection_url(url), body=body, depth=depth, expected={207})
+        return parse_discovery_multistatus(payload)
+
     def list_objects(self) -> CalDAVReportResult:
         body = b"""<?xml version="1.0" encoding="utf-8"?>
 <C:calendar-query xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav">
@@ -182,6 +299,8 @@ class CalDAVClient:
             headers.update(dict(extra_headers))
         status, response_headers, payload = self.transport(method, url, headers, body, self.timeout)
         if status not in expected:
+            if status == 404:
+                raise CalDAVNotFound(f"{method} {url} returned HTTP {status}")
             if status == 412:
                 raise CalDAVPreconditionFailed(f"{method} {url} failed because the remote resource changed")
             raise CalDAVError(f"{method} {url} returned HTTP {status}")
@@ -189,14 +308,16 @@ class CalDAVClient:
 
 
 def urllib_transport(method: str, url: str, headers: Mapping[str, str], body: bytes | None, timeout: int) -> tuple[int, Mapping[str, str], bytes]:
-    request = urllib.request.Request(url, data=body, headers=dict(headers), method=method)
     try:
+        request = urllib.request.Request(url, data=body, headers=dict(headers), method=method)
         with urllib.request.urlopen(request, timeout=timeout) as response:
             return response.status, dict(response.headers.items()), response.read()
     except urllib.error.HTTPError as exc:
         return exc.code, dict(exc.headers.items()), exc.read()
     except urllib.error.URLError as exc:
         raise CalDAVError(f"{method} {url} failed: {exc.reason}") from exc
+    except ValueError as exc:
+        raise CalDAVError(f"{method} {url} failed: {exc}") from exc
 
 
 def parse_multistatus(payload: bytes) -> CalDAVReportResult:
@@ -232,10 +353,80 @@ def parse_multistatus(payload: bytes) -> CalDAVReportResult:
     return CalDAVReportResult(objects=objects, sync_token=sync_token, ctag=ctag)
 
 
+def parse_discovery_multistatus(payload: bytes) -> list[_DAVDiscoveryResponse]:
+    try:
+        root = ElementTree.fromstring(payload)
+    except ElementTree.ParseError as exc:
+        raise CalDAVError(f"Invalid CalDAV XML response: {exc}") from exc
+    responses: list[_DAVDiscoveryResponse] = []
+    for response in child_elements(root, "response"):
+        href = first_child_text(response, "href")
+        if not href:
+            continue
+        display_name = None
+        color = None
+        ctag = None
+        sync_token = None
+        is_calendar = False
+        principal_hrefs: list[str] = []
+        calendar_home_set_hrefs: list[str] = []
+        supported_components: list[str] = []
+        for propstat in child_elements(response, "propstat"):
+            status = first_child_text(propstat, "status") or ""
+            if status and " 200 " not in status and not status.endswith(" 200") and " 207 " not in status:
+                continue
+            prop = first_child(propstat, "prop")
+            if prop is None:
+                continue
+            for item in prop:
+                name = local_name(item.tag)
+                if name == "displayname" and item.text:
+                    display_name = item.text.strip() or display_name
+                elif name == "calendar-color" and item.text:
+                    color = item.text.strip() or color
+                elif name == "getctag" and item.text:
+                    ctag = item.text.strip() or ctag
+                elif name == "sync-token" and item.text:
+                    sync_token = item.text.strip() or sync_token
+                elif name == "resourcetype":
+                    is_calendar = is_calendar or any(local_name(child.tag) == "calendar" for child in item)
+                elif name in {"current-user-principal", "principal-URL"}:
+                    principal_hrefs.extend(nested_href_texts(item))
+                elif name == "calendar-home-set":
+                    calendar_home_set_hrefs.extend(nested_href_texts(item))
+                elif name == "supported-calendar-component-set":
+                    for component in item:
+                        if local_name(component.tag) == "comp":
+                            component_name = (component.attrib.get("name") or "").strip().upper()
+                            if component_name:
+                                supported_components.append(component_name)
+        responses.append(
+            _DAVDiscoveryResponse(
+                href=href,
+                display_name=display_name,
+                color=color,
+                ctag=ctag,
+                sync_token=sync_token,
+                is_calendar=is_calendar,
+                principal_hrefs=tuple(dict.fromkeys(principal_hrefs)),
+                calendar_home_set_hrefs=tuple(dict.fromkeys(calendar_home_set_hrefs)),
+                supported_components=tuple(dict.fromkeys(supported_components)),
+            )
+        )
+    return responses
+
+
 def ensure_collection_url(value: str) -> str:
+    value = value.strip()
+    if value and "://" not in value and not value.startswith("/"):
+        value = f"https://{value}"
     return value if value.endswith("/") else f"{value}/"
 
 
+def absolute_dav_url(base_url: str, href: str) -> str:
+    return urllib.parse.urljoin(ensure_collection_url(base_url), href)
+
+
 def strip_weak_etag(value: str | None) -> str | None:
     if value is None:
         return None
@@ -271,5 +462,13 @@ def child_elements(element: ElementTree.Element, name: str) -> list[ElementTree.
     return [child for child in element if local_name(child.tag) == name]
 
 
+def nested_href_texts(element: ElementTree.Element) -> list[str]:
+    hrefs: list[str] = []
+    for child in element.iter():
+        if local_name(child.tag) == "href" and child.text and child.text.strip():
+            hrefs.append(child.text.strip())
+    return hrefs
+
+
 def local_name(tag: str) -> str:
     return tag.rsplit("}", 1)[-1] if "}" in tag else tag

src/govoplan_calendar/backend/db/models.py

@@ -29,7 +29,7 @@ class CalendarCollection(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenancy_tenants.id", ondelete="CASCADE"), nullable=False, index=True)
     slug: Mapped[str] = mapped_column(String(100), nullable=False)
     name: Mapped[str] = mapped_column(String(255), nullable=False)
     description: Mapped[str | None] = mapped_column(Text)
@@ -39,7 +39,7 @@ class CalendarCollection(Base, TimestampMixin):
     owner_id: Mapped[str | None] = mapped_column(String(36), nullable=True, index=True)
     visibility: Mapped[str] = mapped_column(String(20), default="tenant", nullable=False, index=True)
     is_default: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False, index=True)
-    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
     metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
 
@@ -56,7 +56,7 @@ class CalendarEvent(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenancy_tenants.id", ondelete="CASCADE"), nullable=False, index=True)
     calendar_id: Mapped[str] = mapped_column(ForeignKey("calendar_collections.id", ondelete="CASCADE"), nullable=False, index=True)
     uid: Mapped[str] = mapped_column(String(255), nullable=False, index=True)
     recurrence_id: Mapped[str | None] = mapped_column(String(255), nullable=True, index=True)
@@ -86,8 +86,8 @@ class CalendarEvent(Base, TimestampMixin):
     etag: Mapped[str | None] = mapped_column(String(255), index=True)
     icalendar: Mapped[dict[str, Any]] = mapped_column(JSON, default=dict, nullable=False)
     raw_ics: Mapped[str | None] = mapped_column(Text)
-    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
-    updated_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
+    updated_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
     metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
 
@@ -110,7 +110,7 @@ class CalendarSyncSource(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenancy_tenants.id", ondelete="CASCADE"), nullable=False, index=True)
     calendar_id: Mapped[str] = mapped_column(ForeignKey("calendar_collections.id", ondelete="CASCADE"), nullable=False, index=True)
     source_kind: Mapped[str] = mapped_column(String(30), default="caldav", nullable=False, index=True)
     collection_url: Mapped[str] = mapped_column(String(1000), nullable=False)
@@ -142,11 +142,11 @@ class CalendarSyncCredential(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenancy_tenants.id", ondelete="CASCADE"), nullable=False, index=True)
     credential_kind: Mapped[str] = mapped_column(String(30), nullable=False, index=True)
     label: Mapped[str | None] = mapped_column(String(255))
     secret_encrypted: Mapped[str | None] = mapped_column(Text)
-    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
     metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
 

src/govoplan_calendar/backend/ical.py

@@ -92,6 +92,8 @@ def parse_vevent_component(calendar: Calendar, event: Event, *, raw_ics: str) ->
     properties = component_property_records(event)
     alarms = [component_alarm_record(alarm) for alarm in event.subcomponents if alarm.name == "VALARM"]
     standard = standard_property_index(properties)
+    if dtend is None and duration_seconds is not None:
+        standard["uses_duration"] = True
 
     return {
         "uid": uid,
@@ -154,7 +156,9 @@ def event_to_component(event: Any) -> Event:
     component.add("uid", event.uid)
     component.add("dtstamp", datetime.now(timezone.utc))
     component.add("dtstart", event_temporal_value(event.start_at, all_day=event.all_day, timezone_id=event.timezone))
-    if event.end_at is not None:
+    if event_uses_duration(event):
+        component.add("duration", timedelta(seconds=int(event.duration_seconds)))
+    elif event.end_at is not None:
         component.add("dtend", event_temporal_value(event.end_at, all_day=event.all_day, timezone_id=event.timezone))
     elif getattr(event, "duration_seconds", None) is not None:
         component.add("duration", timedelta(seconds=int(event.duration_seconds)))
@@ -474,6 +478,16 @@ def metadata_value(event: Any, key: str) -> str | None:
     return str(value) if value else None
 
 
+def event_uses_duration(event: Any) -> bool:
+    if getattr(event, "duration_seconds", None) is None:
+        return False
+    raw_metadata = getattr(event, "icalendar", None)
+    if not isinstance(raw_metadata, dict):
+        return False
+    standard = raw_metadata.get("standard")
+    return isinstance(standard, dict) and standard.get("uses_duration") is True
+
+
 def event_temporal_value(value: datetime, *, all_day: bool, timezone_id: str | None) -> date | datetime:
     value = normalize_datetime(value)
     if all_day:

src/govoplan_calendar/backend/migrations/versions/7c8d9e0f1a2b_calendar_collections_events.py

@@ -1,7 +1,7 @@
 """calendar collections and VEVENT storage
 
 Revision ID: 7c8d9e0f1a2b
-Revises: 1b2c3d4e5f70
+Revises: 2e3f4a5b6c7d
 Create Date: 2026-07-07 00:00:00.000000
 """
 from __future__ import annotations
@@ -11,7 +11,7 @@ import sqlalchemy as sa
 
 
 revision = "7c8d9e0f1a2b"
-down_revision = "1b2c3d4e5f70"
+down_revision = "2e3f4a5b6c7d"
 branch_labels = None
 depends_on = None
 
@@ -38,8 +38,8 @@ def upgrade() -> None:
             sa.Column("metadata", sa.JSON(), nullable=True),
             sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
             sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
-            sa.ForeignKeyConstraint(["created_by_user_id"], ["users.id"], name=op.f("fk_calendar_collections_created_by_user_id_users"), ondelete="SET NULL"),
-            sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_collections_tenant_id_tenants"), ondelete="CASCADE"),
+            sa.ForeignKeyConstraint(["created_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_collections_created_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["tenant_id"], ["tenancy_tenants.id"], name=op.f("fk_calendar_collections_tenant_id_tenants"), ondelete="CASCADE"),
             sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_collections")),
         )
         op.create_index(op.f("ix_calendar_collections_tenant_id"), "calendar_collections", ["tenant_id"], unique=False)
@@ -100,9 +100,9 @@ def upgrade() -> None:
             sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
             sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
             sa.ForeignKeyConstraint(["calendar_id"], ["calendar_collections.id"], name=op.f("fk_calendar_events_calendar_id_calendar_collections"), ondelete="CASCADE"),
-            sa.ForeignKeyConstraint(["created_by_user_id"], ["users.id"], name=op.f("fk_calendar_events_created_by_user_id_users"), ondelete="SET NULL"),
-            sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_events_tenant_id_tenants"), ondelete="CASCADE"),
-            sa.ForeignKeyConstraint(["updated_by_user_id"], ["users.id"], name=op.f("fk_calendar_events_updated_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["created_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_events_created_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["tenant_id"], ["tenancy_tenants.id"], name=op.f("fk_calendar_events_tenant_id_tenants"), ondelete="CASCADE"),
+            sa.ForeignKeyConstraint(["updated_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_events_updated_by_user_id_users"), ondelete="SET NULL"),
             sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_events")),
             sa.UniqueConstraint("calendar_id", "uid", "recurrence_id", name="uq_calendar_events_calendar_uid_recurrence"),
         )

src/govoplan_calendar/backend/migrations/versions/8d9e0f1a2b3c_caldav_sync_sources.py

@@ -42,7 +42,7 @@ def upgrade() -> None:
         sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
         sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
         sa.ForeignKeyConstraint(["calendar_id"], ["calendar_collections.id"], name=op.f("fk_calendar_sync_sources_calendar_id_calendar_collections"), ondelete="CASCADE"),
-        sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_sync_sources_tenant_id_tenants"), ondelete="CASCADE"),
+        sa.ForeignKeyConstraint(["tenant_id"], ["tenancy_tenants.id"], name=op.f("fk_calendar_sync_sources_tenant_id_tenants"), ondelete="CASCADE"),
         sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_sync_sources")),
     )
     for column in ("tenant_id", "calendar_id", "source_kind", "deleted_at"):

src/govoplan_calendar/backend/migrations/versions/9e0f1a2b3c4d_caldav_credentials_outbound_sync.py

@@ -47,8 +47,8 @@ def upgrade() -> None:
             sa.Column("metadata", sa.JSON(), nullable=True),
             sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
             sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
-            sa.ForeignKeyConstraint(["created_by_user_id"], ["users.id"], name=op.f("fk_calendar_sync_credentials_created_by_user_id_users"), ondelete="SET NULL"),
-            sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_sync_credentials_tenant_id_tenants"), ondelete="CASCADE"),
+            sa.ForeignKeyConstraint(["created_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_sync_credentials_created_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["tenant_id"], ["tenancy_tenants.id"], name=op.f("fk_calendar_sync_credentials_tenant_id_tenants"), ondelete="CASCADE"),
             sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_sync_credentials")),
         )
         for column in ("tenant_id", "credential_kind", "created_by_user_id", "deleted_at"):

src/govoplan_calendar/backend/router.py

@@ -6,9 +6,14 @@ from fastapi import APIRouter, Body, Depends, HTTPException, Query, Response, st
 from sqlalchemy.orm import Session
 
 from govoplan_access.backend.auth.dependencies import ApiPrincipal, get_api_principal, has_scope
+from govoplan_core.api.v1.schemas import DeltaDeletedItem
+from govoplan_core.core.change_sequence import decode_sequence_watermark, encode_sequence_watermark, max_sequence_id, sequence_entries_since, sequence_watermark_is_expired
+from govoplan_calendar.backend.db.models import CalendarEvent
 from govoplan_calendar.backend.ical import ICalendarError, event_to_ics, http_last_modified
 from govoplan_calendar.backend.caldav import CalDAVError
 from govoplan_calendar.backend.schemas import (
+    CalendarCalDavDiscoveryRequest,
+    CalendarCalDavDiscoveryResponse,
     CalendarCalDavDueSyncItemResponse,
     CalendarCalDavDueSyncResponse,
     CalendarCalDavSourceCreateRequest,
@@ -23,24 +28,39 @@ from govoplan_calendar.backend.schemas import (
     CalendarCollectionResponse,
     CalendarCollectionUpdateRequest,
     CalendarEventCreateRequest,
+    CalendarEventDeltaResponse,
     CalendarEventListResponse,
     CalendarEventResponse,
     CalendarEventUpdateRequest,
     CalendarFreeBusyRequest,
     CalendarFreeBusyResponse,
     CalendarIcsImportRequest,
+    CalendarSyncDueSyncItemResponse,
+    CalendarSyncDueSyncResponse,
+    CalendarSyncSourceCreateRequest,
+    CalendarSyncSourceListResponse,
+    CalendarSyncSourceResponse,
+    CalendarSyncSourceSyncRequest,
+    CalendarSyncSourceSyncResponse,
+    CalendarSyncSourceUpdateRequest,
 )
 from govoplan_calendar.backend.service import (
+    CALENDAR_EVENTS_COLLECTION,
+    CALENDAR_EVENT_RESOURCE,
+    CALENDAR_MODULE_ID,
     CalendarError,
     caldav_source_response,
     caldav_sync_response,
     calendar_response,
     create_calendar,
     create_caldav_source,
+    create_sync_source,
     create_event,
     delete_calendar,
     delete_caldav_source,
+    delete_sync_source,
     delete_event,
+    discover_caldav_calendars,
     event_response,
     get_caldav_source,
     get_event,
@@ -49,10 +69,15 @@ from govoplan_calendar.backend.service import (
     list_caldav_sources,
     list_calendars,
     list_events,
+    list_sync_sources,
+    normalize_datetime,
+    sync_due_sources,
     sync_due_caldav_sources,
     sync_caldav_source,
+    sync_source,
     update_calendar,
     update_caldav_source,
+    update_sync_source,
     update_event,
 )
 from govoplan_core.db.session import get_session
@@ -78,10 +103,123 @@ def _event_response(event) -> CalendarEventResponse:
     return CalendarEventResponse.model_validate(event_response(event))
 
 
+def _calendar_event_watermark(session: Session, tenant_id: str) -> str:
+    return encode_sequence_watermark(
+        max_sequence_id(session, tenant_id=tenant_id, module_id=CALENDAR_MODULE_ID, collections=(CALENDAR_EVENTS_COLLECTION,))
+    )
+
+
+def _parse_payload_datetime(value) -> datetime | None:
+    if not isinstance(value, str) or not value:
+        return None
+    try:
+        return datetime.fromisoformat(value)
+    except ValueError:
+        return None
+
+
+def _event_interval_overlaps(payload: dict, *, prefix: str, start_at: datetime | None, end_at: datetime | None) -> bool:
+    event_start = _parse_payload_datetime(payload.get(f"{prefix}start_at"))
+    event_end = _parse_payload_datetime(payload.get(f"{prefix}end_at")) or event_start
+    if event_start is None:
+        return False
+    if start_at is not None and event_end is not None and event_end < normalize_datetime(start_at):
+        return False
+    if end_at is not None and event_start > normalize_datetime(end_at):
+        return False
+    return True
+
+
+def _event_payload_matches_window(entry, *, calendar_id: str | None, start_at: datetime | None, end_at: datetime | None) -> bool:
+    payload = entry.payload or {}
+    current_calendar = payload.get("calendar_id")
+    previous_calendar = payload.get("previous_calendar_id")
+    current_calendar_matches = calendar_id is None or current_calendar == calendar_id
+    previous_calendar_matches = calendar_id is None or previous_calendar == calendar_id
+    return (
+        current_calendar_matches and _event_interval_overlaps(payload, prefix="", start_at=start_at, end_at=end_at)
+    ) or (
+        previous_calendar_matches and _event_interval_overlaps(payload, prefix="previous_", start_at=start_at, end_at=end_at)
+    )
+
+
+def _visible_events_for_delta(
+    session: Session,
+    *,
+    tenant_id: str,
+    event_ids: list[str],
+    calendar_id: str | None,
+    start_at: datetime | None,
+    end_at: datetime | None,
+) -> list[CalendarEvent]:
+    if not event_ids:
+        return []
+    query = session.query(CalendarEvent).filter(
+        CalendarEvent.tenant_id == tenant_id,
+        CalendarEvent.id.in_(event_ids),
+        CalendarEvent.deleted_at.is_(None),
+    )
+    if calendar_id:
+        query = query.filter(CalendarEvent.calendar_id == calendar_id)
+    if start_at is not None:
+        normalized_start = normalize_datetime(start_at)
+        query = query.filter((CalendarEvent.end_at.is_(None)) | (CalendarEvent.end_at >= normalized_start))
+    if end_at is not None:
+        query = query.filter(CalendarEvent.start_at <= normalize_datetime(end_at))
+    return query.order_by(CalendarEvent.start_at.asc(), CalendarEvent.summary.asc(), CalendarEvent.id.asc()).all()
+
+
+def _full_event_delta_response(
+    session: Session,
+    *,
+    tenant_id: str,
+    calendar_id: str | None,
+    start_at: datetime | None,
+    end_at: datetime | None,
+) -> CalendarEventDeltaResponse:
+    events = list_events(session, tenant_id=tenant_id, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    return CalendarEventDeltaResponse(
+        events=[_event_response(event) for event in events],
+        deleted=[],
+        watermark=_calendar_event_watermark(session, tenant_id),
+        has_more=False,
+        full=True,
+    )
+
+
+def _event_delta_entries(session: Session, *, tenant_id: str, since: str, limit: int):
+    try:
+        since_sequence = decode_sequence_watermark(since)
+    except ValueError as exc:
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(exc)) from exc
+    if sequence_watermark_is_expired(
+        session,
+        since=since_sequence,
+        tenant_id=tenant_id,
+        module_id=CALENDAR_MODULE_ID,
+        collections=(CALENDAR_EVENTS_COLLECTION,),
+    ):
+        return None, False
+    entries_plus_one = sequence_entries_since(
+        session,
+        since=since_sequence,
+        tenant_id=tenant_id,
+        module_id=CALENDAR_MODULE_ID,
+        collections=(CALENDAR_EVENTS_COLLECTION,),
+        limit=limit + 1,
+    )
+    has_more = len(entries_plus_one) > limit
+    return entries_plus_one[:limit], has_more
+
+
 def _caldav_source_response(source) -> CalendarCalDavSourceResponse:
     return CalendarCalDavSourceResponse.model_validate(caldav_source_response(source))
 
 
+def _sync_source_response(source) -> CalendarSyncSourceResponse:
+    return CalendarSyncSourceResponse.model_validate(caldav_source_response(source))
+
+
 @router.get("/calendars", response_model=CalendarCollectionListResponse)
 def api_list_calendars(
     principal: ApiPrincipal = Depends(get_api_principal),
@@ -107,7 +245,7 @@ def api_create_calendar(
         return _calendar_response(calendar)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.patch("/calendars/{calendar_id}", response_model=CalendarCollectionResponse)
@@ -142,7 +280,124 @@ def api_delete_calendar(
         return Response(status_code=status.HTTP_204_NO_CONTENT)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.get("/sync-sources", response_model=CalendarSyncSourceListResponse)
+def api_list_sync_sources(
+    calendar_id: str | None = None,
+    source_kind: str | None = None,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:read")
+    sources = list_sync_sources(session, tenant_id=principal.tenant_id, calendar_id=calendar_id, source_kind=source_kind)
+    return CalendarSyncSourceListResponse(sources=[_sync_source_response(source) for source in sources])
+
+
+@router.post("/sync-sources", response_model=CalendarSyncSourceResponse, status_code=status.HTTP_201_CREATED)
+def api_create_sync_source(
+    payload: CalendarSyncSourceCreateRequest,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        source = create_sync_source(session, tenant_id=principal.tenant_id, user_id=principal.user.id, payload=payload)
+        session.commit()
+        session.refresh(source)
+        return _sync_source_response(source)
+    except CalendarError as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.patch("/sync-sources/{source_id}", response_model=CalendarSyncSourceResponse)
+def api_update_sync_source(
+    source_id: str,
+    payload: CalendarSyncSourceUpdateRequest,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        source = update_sync_source(session, tenant_id=principal.tenant_id, source_id=source_id, payload=payload)
+        session.commit()
+        session.refresh(source)
+        return _sync_source_response(source)
+    except CalendarError as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.delete("/sync-sources/{source_id}", status_code=status.HTTP_204_NO_CONTENT)
+def api_delete_sync_source(
+    source_id: str,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        delete_sync_source(session, tenant_id=principal.tenant_id, source_id=source_id)
+        session.commit()
+        return Response(status_code=status.HTTP_204_NO_CONTENT)
+    except CalendarError as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=str(exc)) from exc
+
+
+@router.post("/sync-sources/{source_id}/sync", response_model=CalendarSyncSourceSyncResponse)
+def api_sync_source(
+    source_id: str,
+    payload: CalendarSyncSourceSyncRequest | None = None,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:event:import")
+    payload = payload or CalendarSyncSourceSyncRequest()
+    try:
+        source, stats = sync_source(
+            session,
+            tenant_id=principal.tenant_id,
+            user_id=principal.user.id,
+            source_id=source_id,
+            password=payload.password,
+            bearer_token=payload.bearer_token,
+            force_full=payload.force_full,
+        )
+        session.commit()
+        session.refresh(source)
+        return CalendarSyncSourceSyncResponse.model_validate(caldav_sync_response(source, stats))
+    except (CalendarError, CalDAVError, ICalendarError) as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.post("/sync-sources/sync-due", response_model=CalendarSyncDueSyncResponse)
+def api_sync_due_sources(
+    limit: int = Query(default=50, ge=1, le=200),
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:event:import")
+    results = sync_due_sources(session, tenant_id=principal.tenant_id, user_id=principal.user.id, limit=limit)
+    session.commit()
+    return CalendarSyncDueSyncResponse(
+        results=[
+            CalendarSyncDueSyncItemResponse(
+                source_id=item.source_id,
+                calendar_id=item.calendar_id,
+                status=item.status,
+                error=item.error,
+                created=item.stats.created if item.stats else 0,
+                updated=item.stats.updated if item.stats else 0,
+                deleted=item.stats.deleted if item.stats else 0,
+                unchanged=item.stats.unchanged if item.stats else 0,
+                fetched=item.stats.fetched if item.stats else 0,
+            )
+            for item in results
+        ]
+    )
 
 
 @router.get("/caldav/sources", response_model=CalendarCalDavSourceListResponse)
@@ -156,6 +411,20 @@ def api_list_caldav_sources(
     return CalendarCalDavSourceListResponse(sources=[_caldav_source_response(source) for source in sources])
 
 
+@router.post("/caldav/discover", response_model=CalendarCalDavDiscoveryResponse)
+def api_discover_caldav_calendars(
+    payload: CalendarCalDavDiscoveryRequest,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        calendars = discover_caldav_calendars(session, tenant_id=principal.tenant_id, payload=payload)
+        return CalendarCalDavDiscoveryResponse(calendars=calendars)
+    except (CalendarError, CalDAVError) as exc:
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
 @router.post("/caldav/sources", response_model=CalendarCalDavSourceResponse, status_code=status.HTTP_201_CREATED)
 def api_create_caldav_source(
     payload: CalendarCalDavSourceCreateRequest,
@@ -170,7 +439,7 @@ def api_create_caldav_source(
         return _caldav_source_response(source)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.patch("/caldav/sources/{source_id}", response_model=CalendarCalDavSourceResponse)
@@ -188,7 +457,7 @@ def api_update_caldav_source(
         return _caldav_source_response(source)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.delete("/caldav/sources/{source_id}", status_code=status.HTTP_204_NO_CONTENT)
@@ -231,7 +500,7 @@ def api_sync_caldav_source(
         return CalendarCalDavSyncResponse.model_validate(caldav_sync_response(source, stats))
     except (CalendarError, CalDAVError, ICalendarError) as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.post("/caldav/sync-due", response_model=CalendarCalDavDueSyncResponse)
@@ -274,6 +543,57 @@ def api_list_events(
     return CalendarEventListResponse(events=[_event_response(event) for event in events])
 
 
+@router.get("/events/delta", response_model=CalendarEventDeltaResponse)
+def api_list_events_delta(
+    calendar_id: str | None = None,
+    start_at: datetime | None = Query(default=None),
+    end_at: datetime | None = Query(default=None),
+    since: str | None = None,
+    limit: int = Query(default=500, ge=1, le=1000),
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:event:read")
+    if since is None:
+        return _full_event_delta_response(session, tenant_id=principal.tenant_id, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    entries, has_more = _event_delta_entries(session, tenant_id=principal.tenant_id, since=since, limit=limit)
+    if entries is None:
+        return _full_event_delta_response(session, tenant_id=principal.tenant_id, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    scoped_entries = [
+        entry
+        for entry in entries
+        if entry.resource_type == CALENDAR_EVENT_RESOURCE and _event_payload_matches_window(entry, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    ]
+    changed_ids = list(dict.fromkeys(entry.resource_id for entry in scoped_entries if entry.operation != "deleted"))
+    visible_events = _visible_events_for_delta(
+        session,
+        tenant_id=principal.tenant_id,
+        event_ids=changed_ids,
+        calendar_id=calendar_id,
+        start_at=start_at,
+        end_at=end_at,
+    )
+    visible_ids = {event.id for event in visible_events}
+    deleted = [
+        DeltaDeletedItem(
+            id=entry.resource_id,
+            resource_type=entry.resource_type,
+            revision=encode_sequence_watermark(entry.id),
+            deleted_at=entry.created_at if entry.operation == "deleted" else None,
+        )
+        for entry in scoped_entries
+        if entry.resource_id not in visible_ids
+    ]
+    watermark = encode_sequence_watermark(entries[-1].id) if has_more and entries else _calendar_event_watermark(session, principal.tenant_id)
+    return CalendarEventDeltaResponse(
+        events=[_event_response(event) for event in visible_events],
+        deleted=deleted,
+        watermark=watermark,
+        has_more=has_more,
+        full=False,
+    )
+
+
 @router.post("/events", response_model=CalendarEventResponse, status_code=status.HTTP_201_CREATED)
 def api_create_event(
     payload: CalendarEventCreateRequest,
@@ -288,7 +608,7 @@ def api_create_event(
         return _event_response(event)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.get("/events/{event_id}", response_model=CalendarEventResponse)
@@ -319,7 +639,7 @@ def api_update_event(
         return _event_response(event)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.delete("/events/{event_id}", status_code=status.HTTP_204_NO_CONTENT)
@@ -330,7 +650,7 @@ def api_delete_event(
 ):
     _require_any_scope(principal, "calendar:event:delete", "calendar:event:write")
     try:
-        delete_event(session, tenant_id=principal.tenant_id, event_id=event_id)
+        delete_event(session, tenant_id=principal.tenant_id, event_id=event_id, user_id=principal.user.id)
         session.commit()
         return Response(status_code=status.HTTP_204_NO_CONTENT)
     except CalendarError as exc:
@@ -362,7 +682,7 @@ def api_import_ics_event(
         return _event_response(event)
     except (CalendarError, ICalendarError) as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.get("/events/{event_id}/ics")
@@ -404,4 +724,4 @@ def api_freebusy(
         )
         return CalendarFreeBusyResponse(start_at=payload.start_at, end_at=payload.end_at, busy=busy)
     except CalendarError as exc:
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc

src/govoplan_calendar/backend/schemas.py

@@ -5,12 +5,15 @@ from typing import Any, Literal
 
 from pydantic import BaseModel, ConfigDict, Field, SecretStr
 
+from govoplan_core.api.v1.schemas import DeltaDeletedItem
+
 
 CalendarOwnerType = Literal["tenant", "user", "group", "resource"]
 CalendarVisibility = Literal["private", "tenant", "shared", "public"]
 CalendarDeleteEventAction = Literal["delete", "move"]
 CalendarSyncAuthType = Literal["none", "basic", "bearer"]
 CalendarSyncDirection = Literal["inbound", "two_way"]
+CalendarSyncSourceKind = Literal["caldav", "ics", "webcal", "graph", "ews"]
 CalendarCalDavConflictPolicy = Literal["etag", "overwrite"]
 
 
@@ -70,9 +73,10 @@ class CalendarCollectionListResponse(BaseModel):
     calendars: list[CalendarCollectionResponse] = Field(default_factory=list)
 
 
-class CalendarCalDavSourceCreateRequest(BaseModel):
+class CalendarSyncSourceCreateRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 
+    source_kind: CalendarSyncSourceKind = "caldav"
     calendar_id: str
     collection_url: str = Field(min_length=1, max_length=1000)
     display_name: str | None = Field(default=None, max_length=255)
@@ -88,7 +92,11 @@ class CalendarCalDavSourceCreateRequest(BaseModel):
     metadata: dict[str, Any] = Field(default_factory=dict)
 
 
-class CalendarCalDavSourceUpdateRequest(BaseModel):
+class CalendarCalDavSourceCreateRequest(CalendarSyncSourceCreateRequest):
+    source_kind: Literal["caldav"] = "caldav"
+
+
+class CalendarSyncSourceUpdateRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 
     calendar_id: str | None = None
@@ -108,7 +116,11 @@ class CalendarCalDavSourceUpdateRequest(BaseModel):
     metadata: dict[str, Any] | None = None
 
 
-class CalendarCalDavSourceResponse(BaseModel):
+class CalendarCalDavSourceUpdateRequest(CalendarSyncSourceUpdateRequest):
+    pass
+
+
+class CalendarSyncSourceResponse(BaseModel):
     id: str
     tenant_id: str
     calendar_id: str
@@ -135,11 +147,44 @@ class CalendarCalDavSourceResponse(BaseModel):
     metadata: dict[str, Any] = Field(default_factory=dict)
 
 
+class CalendarCalDavSourceResponse(CalendarSyncSourceResponse):
+    pass
+
+
+class CalendarSyncSourceListResponse(BaseModel):
+    sources: list[CalendarSyncSourceResponse] = Field(default_factory=list)
+
+
 class CalendarCalDavSourceListResponse(BaseModel):
     sources: list[CalendarCalDavSourceResponse] = Field(default_factory=list)
 
 
-class CalendarCalDavSyncRequest(BaseModel):
+class CalendarCalDavDiscoveryRequest(BaseModel):
+    model_config = ConfigDict(extra="forbid")
+
+    url: str = Field(min_length=1, max_length=1000)
+    source_id: str | None = None
+    auth_type: CalendarSyncAuthType | None = None
+    username: str | None = Field(default=None, max_length=255)
+    credential_ref: str | None = Field(default=None, max_length=255)
+    password: SecretStr | None = None
+    bearer_token: SecretStr | None = None
+
+
+class CalendarCalDavDiscoveryCalendarResponse(BaseModel):
+    collection_url: str
+    href: str
+    display_name: str | None = None
+    color: str | None = None
+    ctag: str | None = None
+    sync_token: str | None = None
+
+
+class CalendarCalDavDiscoveryResponse(BaseModel):
+    calendars: list[CalendarCalDavDiscoveryCalendarResponse] = Field(default_factory=list)
+
+
+class CalendarSyncSourceSyncRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 
     password: str | None = None
@@ -147,8 +192,12 @@ class CalendarCalDavSyncRequest(BaseModel):
     force_full: bool = False
 
 
-class CalendarCalDavSyncResponse(BaseModel):
-    source: CalendarCalDavSourceResponse
+class CalendarCalDavSyncRequest(CalendarSyncSourceSyncRequest):
+    pass
+
+
+class CalendarSyncSourceSyncResponse(BaseModel):
+    source: CalendarSyncSourceResponse
     created: int = 0
     updated: int = 0
     deleted: int = 0
@@ -161,7 +210,11 @@ class CalendarCalDavSyncResponse(BaseModel):
     errors: list[str] = Field(default_factory=list)
 
 
-class CalendarCalDavDueSyncItemResponse(BaseModel):
+class CalendarCalDavSyncResponse(CalendarSyncSourceSyncResponse):
+    source: CalendarCalDavSourceResponse
+
+
+class CalendarSyncDueSyncItemResponse(BaseModel):
     source_id: str
     calendar_id: str
     status: str
@@ -173,6 +226,14 @@ class CalendarCalDavDueSyncItemResponse(BaseModel):
     fetched: int = 0
 
 
+class CalendarCalDavDueSyncItemResponse(CalendarSyncDueSyncItemResponse):
+    pass
+
+
+class CalendarSyncDueSyncResponse(BaseModel):
+    results: list[CalendarSyncDueSyncItemResponse] = Field(default_factory=list)
+
+
 class CalendarCalDavDueSyncResponse(BaseModel):
     results: list[CalendarCalDavDueSyncItemResponse] = Field(default_factory=list)
 
@@ -283,6 +344,14 @@ class CalendarEventListResponse(BaseModel):
     events: list[CalendarEventResponse] = Field(default_factory=list)
 
 
+class CalendarEventDeltaResponse(BaseModel):
+    events: list[CalendarEventResponse] = Field(default_factory=list)
+    deleted: list[DeltaDeletedItem] = Field(default_factory=list)
+    watermark: str | None = None
+    has_more: bool = False
+    full: bool = False
+
+
 class CalendarFreeBusyRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 

src/govoplan_calendar/backend/tasks.py

@@ -5,11 +5,11 @@ from celery import shared_task
 
 @shared_task(name="govoplan_calendar.sync_due_caldav_sources")
 def sync_due_caldav_sources_task(tenant_id: str | None = None, limit: int = 50) -> list[dict[str, object]]:
-    from govoplan_calendar.backend.service import sync_due_caldav_sources
+    from govoplan_calendar.backend.service import sync_due_sources
     from govoplan_core.db.session import get_database
 
     with get_database().SessionLocal() as session:
-        results = sync_due_caldav_sources(session, tenant_id=tenant_id, limit=limit)
+        results = sync_due_sources(session, tenant_id=tenant_id, limit=limit)
         session.commit()
         return [
             {