Declare calendar route View surface

.gitignore

@@ -118,6 +118,7 @@ dist
 .template-preview-test-build/
 .import-test-build/
 webui/.component-test-build/
+webui/.calendar-picker-test-build/
 webui/.module-test-build/
 webui/.policy-test-build/
 webui/.template-preview-test-build/

README.md

@@ -1,5 +1,9 @@
 # govoplan-calendar
 
+<!-- govoplan-repository-type:start -->
+**Repository type:** module (domain).
+<!-- govoplan-repository-type:end -->
+
 GovOPlaN Calendar is the standalone calendar module. It provides tenant calendar collections, iCalendar/VEVENT event storage, a calendar WebUI, and integration boundaries for scheduling, tasks, mail, appointments, workflow, notifications, and external groupware.
 
 ## Ownership
@@ -36,9 +40,21 @@ The first backend implementation stores VEVENT data in two layers:
 CalDAV sync is implemented as a calendar-owned backend primitive. A CalDAV source
 records the remote collection URL, sync token, ETag/ctag state, username,
 credential reference, sync interval, sync direction, and conflict policy.
-Credentials can be supplied transiently for manual sync, referenced from
+Credentials can be supplied transiently for manual sync. Persisted API-managed
-environment variables with `env:NAME`, stored through a platform secret provider
+sources accept only a password or token: Calendar stores an opaque, tenant- and
-when one is available, or stored as encrypted calendar-owned credentials.
+source-bound local reference, backed by the platform secret provider when one is
+available or by an encrypted calendar-owned credential otherwise. Caller-selected
+environment and external-provider references are rejected. Trusted deployment
+code may resolve an `env:NAME` reference only through the separate deployment
+configuration helper.
+
+Deleting a source or its calendar immediately scrubs Calendar-owned ciphertext
+and provider references and emits non-secret audit evidence. If an external
+secret provider cannot confirm deletion, the operation fails closed without
+retiring the source or cancelling its queued work; retry is idempotent after a
+database rollback. Destructive module retirement first deletes and audits all
+active and legacy retained provider secrets and stops before table removal on
+provider failure.
 
 Inbound sync uses CalDAV `calendar-query` for full sync and `sync-collection`
 when a sync token exists. It imports all VEVENT components in a resource and

docs/CALENDAR_INTEGRATION_CONCEPT.md

@@ -24,10 +24,94 @@ The first standalone module provides:
 - API endpoints for listing calendars, creating/updating/deleting events, importing iCalendar, and exporting event ICS
 - free/busy API primitive with recurrence expansion for scheduling and appointment conflict checks
 - calendar-owned CalDAV sync sources with credential references, scheduled due-sync metadata, full/incremental inbound sync, two-way PUT/DELETE writes, and ETag conflict handling
+- a Calendar-owned durable desired-state outbox for two-way CalDAV writes. Event
+  state and the exact external resource snapshot commit atomically; workers use
+  deterministic hrefs, conditional requests, expiring leases, bounded
+  exponential retry, and semantic GET reconciliation after ambiguous outcomes
 - WebUI views: month, week, workweek, day, and continuous week-row scrolling
 
 The first implementation is not yet a full CalDAV network server. It is the internal calendar storage, sync, availability, and UI foundation on which Open-Xchange integration, richer recurrence editing, scheduling inbox/outbox behavior, and CalDAV server endpoints can be built.
 
+## Outbound delivery operations
+
+No event API or cross-module capability performs CalDAV network I/O inside the
+caller's transaction. A local mutation instead creates a
+`calendar_outbox_operations` row containing the exact desired ICS resource,
+target href, expected ETag, conflict-policy snapshot, and idempotency key.
+
+The registered `govoplan.calendar.dispatch_outbox` worker commits an expiring
+lease before doing network I/O and commits each outcome independently. If a
+worker loses the database connection after a successful remote write, the next
+attempt reads the remote object and compares semantic ICS fingerprints. A
+matching PUT or an already absent DELETE completes successfully without a blind
+duplicate write. Pending updates for one href supersede older never-attempted
+rows; attempted predecessors are reconciled first, and updates queued behind an
+in-flight write inherit the ETag produced by that write. Delivery and inbound
+REPORT application take the same source-row lock,
+and only one operation per source is leased at a time. This deliberately trades
+per-source throughput for a simple ordering guarantee: a stale inbound report
+cannot land after a newer outbound result, and queued leases do not expire while
+waiting behind another network request for the same source.
+
+Operators can list, dispatch, retry, reconcile, and discard tenant operations
+through the `/calendar/caldav/outbox` administration endpoints. Terminal ETag
+conflicts and exhausted retries remain the current local desired state and
+shield that resource from inbound overwrite until explicitly resolved.
+Discarding is the administrator's accept-remote transition: it is allowed only
+for the latest generation, atomically cancels its unresolved predecessor chain,
+marks the event projection as discarded, clears the sync token, and schedules a
+full inbound reconciliation so an unchanged remote object is not missed.
+
+Disabling outbound delivery or switching to inbound-only is rejected while
+unresolved desired state exists; retirement is the explicit exception and
+cancels unresolved work. Endpoint/calendar changes also require no active event
+bindings or unresolved delivery. Credential rotation does not discard committed
+desired state. Public event mutation cannot set sync-owned source hrefs, kinds,
+or ETags. Deleting a synchronized collection or retiring its source is a local
+unlink: it never deletes the remote collection or its remaining remote events.
+The unlink immediately scrubs Calendar-owned credential ciphertext and external
+provider references and audits the deletion. External provider failure blocks
+retirement before queued work is changed; a later retry tolerates a provider
+secret already removed by an earlier attempt whose database transaction rolled
+back. Provider errors and audit details never contain credential values or
+secret references.
+The current singular ownership model permits one active sync source per
+calendar; multi-source fan-in will require per-event source routing. Celery beat
+triggers recovery every minute, while root-transaction after-commit dispatch
+provides the normal low-latency path.
+
+### Collection retirement and bulk event moves
+
+Collection deletion accepts two explicit, non-destructive external actions for
+`event_action="move"`:
+
+- `detach_keep_remote` applies only when the source collection is synchronized
+  and the target is local. It moves the local event projections, clears their
+  sync-owned source kind, href, ETag, and CalDAV projection metadata, retires
+  the source locally, and cancels undelivered outbox state. An active delivery
+  lease blocks the transaction. The action never enqueues a remote DELETE, so
+  the remote collection and remote events remain unchanged.
+- `copy_to_remote` applies only when the source is local and the target has an
+  active, enabled, two-way CalDAV source. It moves the local events and commits
+  destination PUT desired states in the durable outbox in the same database
+  transaction. Remote failures therefore remain visible and retryable without
+  rolling back or hiding the local move.
+
+Local-to-local moves retain their existing behavior and do not accept an
+`external_action`. Implicit or mismatched actions, inbound-only destinations,
+and synchronized-to-synchronized moves are rejected. `remote_move` is a known
+but deliberately unsupported action: implementing it requires a separately
+approved saga for destination reconciliation, conditional source deletion,
+collision handling, and concurrent-edit policy. The WebUI does not offer that
+destructive mode.
+
+Resolved terminal rows (`succeeded`, `superseded`, and `cancelled`) are removed
+in bounded batches after `CALENDAR_OUTBOX_TERMINAL_RETENTION_DAYS` (90 days by
+default; `0` disables cleanup). `conflict` and `dead` rows are never removed by
+this cleanup because they still carry unresolved local desired state. Each
+periodic or after-commit dispatch also performs one bounded cleanup batch for
+the same tenant scope.
+
 ## Integration Points
 
 ### Scheduling

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@govoplan/calendar-webui",
-  "version": "0.1.6",
+  "version": "0.1.8",
   "private": true,
   "type": "module",
   "main": "webui/src/index.ts",
@@ -19,7 +19,7 @@
     "LICENSE"
   ],
   "peerDependencies": {
-    "@govoplan/core-webui": "^0.1.6",
+    "@govoplan/core-webui": "^0.1.9",
     "lucide-react": "^1.23.0",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",

pyproject.toml

@@ -4,15 +4,16 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "govoplan-calendar"
-version = "0.1.6"
+version = "0.1.8"
 description = "GovOPlaN calendar module with VEVENT storage and WebUI integration."
 readme = "README.md"
 requires-python = ">=3.12"
 license = { file = "LICENSE" }
 authors = [{ name = "GovOPlaN" }]
 dependencies = [
-  "govoplan-core>=0.1.6",
+  "govoplan-core>=0.1.9",
-  "govoplan-access>=0.1.6",
+  "govoplan-access>=0.1.8",
+  "defusedxml>=0.7,<1",
   "icalendar>=7.2",
   "python-dateutil>=2.9",
 ]

src/govoplan_calendar/__init__.py

@@ -2,4 +2,4 @@
 
 __all__ = ["__version__"]
 
-__version__ = "0.1.4"
+__version__ = "0.1.8"

src/govoplan_calendar/backend/caldav.py

@@ -1,12 +1,20 @@
 from __future__ import annotations
 
 import base64
+import posixpath
 import urllib.error
 import urllib.parse
 import urllib.request
 from dataclasses import dataclass, field
-from typing import Mapping, Protocol
+from typing import Any, Mapping, Protocol
-from xml.etree import ElementTree
+
+from defusedxml import ElementTree as SafeElementTree
+from govoplan_core.security.outbound_http import (
+    OutboundHttpError,
+    bounded_response_bytes,
+    build_outbound_http_opener,
+    validate_outbound_http_url,
+)
 
 
 class CalDAVError(RuntimeError):
@@ -75,6 +83,18 @@ class _DAVDiscoveryResponse:
     supported_components: tuple[str, ...] = ()
 
 
+@dataclass(slots=True)
+class _DAVDiscoveryDraft:
+    display_name: str | None = None
+    color: str | None = None
+    ctag: str | None = None
+    sync_token: str | None = None
+    is_calendar: bool = False
+    principal_hrefs: list[str] = field(default_factory=list)
+    calendar_home_set_hrefs: list[str] = field(default_factory=list)
+    supported_components: list[str] = field(default_factory=list)
+
+
 class CalDAVClient:
     def __init__(
         self,
@@ -228,8 +248,23 @@ class CalDAVClient:
         return parse_multistatus(payload)
 
     def fetch_object(self, href: str) -> str:
-        payload = self.request("GET", self.object_url(href), body=None, depth=None, expected={200})
+        return self.fetch_object_state(href).calendar_data or ""
-        return payload.decode("utf-8")
+
+    def fetch_object_state(self, href: str) -> CalDAVObject:
+        """Fetch a resource together with its ETag for outbox reconciliation."""
+
+        _status, headers, payload = self.request_raw(
+            "GET",
+            self.object_url(href),
+            body=None,
+            depth=None,
+            expected={200},
+        )
+        return CalDAVObject(
+            href=href,
+            etag=response_etag(headers),
+            calendar_data=payload.decode("utf-8"),
+        )
 
     def put_object(self, href: str, ics: str, *, etag: str | None = None, create: bool = False, overwrite: bool = False) -> CalDAVWriteResult:
         headers = {"Content-Type": "text/calendar; charset=utf-8"}
@@ -266,7 +301,21 @@ class CalDAVClient:
         return CalDAVWriteResult(href=href, etag=response_etag(response_headers), status=status)
 
     def object_url(self, href: str) -> str:
-        return urllib.parse.urljoin(self.collection_url, href)
+        candidate = same_origin_dav_url(
+            self.collection_url,
+            href,
+            label="CalDAV object href",
+        )
+        collection_parts = urllib.parse.urlparse(self.collection_url)
+        candidate_parts = urllib.parse.urlparse(candidate)
+        collection_path = posixpath.normpath(urllib.parse.unquote(collection_parts.path))
+        candidate_path = posixpath.normpath(urllib.parse.unquote(candidate_parts.path))
+        collection_prefix = collection_path.rstrip("/") + "/"
+        if not candidate_path.startswith(collection_prefix) or candidate_path == collection_path:
+            raise CalDAVError("CalDAV object href must remain inside the configured collection path")
+        if candidate_parts.query or candidate_parts.fragment:
+            raise CalDAVError("CalDAV object href must not contain a query or fragment")
+        return urllib.parse.urlunparse(candidate_parts)
 
     def request(self, method: str, url: str, *, body: bytes | None, depth: str | None, expected: set[int]) -> bytes:
         _status, _headers, payload = self.request_raw(method, url, body=body, depth=depth, expected=expected)
@@ -308,22 +357,40 @@ class CalDAVClient:
 
 
 def urllib_transport(method: str, url: str, headers: Mapping[str, str], body: bytes | None, timeout: int) -> tuple[int, Mapping[str, str], bytes]:
+    url = validate_http_url(url)
     try:
-        request = urllib.request.Request(url, data=body, headers=dict(headers), method=method)
+        url = validate_outbound_http_url(url, label="CalDAV URL")
-        with urllib.request.urlopen(request, timeout=timeout) as response:
+        request = urllib.request.Request(  # noqa: S310 - URL is validated and origin-confined.
-            return response.status, dict(response.headers.items()), response.read()
+            url,
+            data=body,
+            headers=dict(headers),
+            method=method,
+        )
+        opener = build_outbound_http_opener(_SameOriginRedirectHandler(url))
+        with opener.open(request, timeout=timeout) as response:  # noqa: S310 - validated CalDAV URL; redirects remain on origin.  # nosec B310  # nosemgrep: python.lang.security.audit.dynamic-urllib-use-detected.dynamic-urllib-use-detected
+            response_headers = dict(response.headers.items())
+            return response.status, response_headers, bounded_response_bytes(
+                response,
+                headers=response_headers,
+                label="CalDAV response",
+            )
     except urllib.error.HTTPError as exc:
-        return exc.code, dict(exc.headers.items()), exc.read()
+        response_headers = dict(exc.headers.items())
+        try:
+            payload = bounded_response_bytes(exc, headers=response_headers, label="CalDAV error response")
+        except OutboundHttpError as policy_exc:
+            raise CalDAVError(f"{method} {url} failed: {policy_exc}") from policy_exc
+        return exc.code, response_headers, payload
     except urllib.error.URLError as exc:
         raise CalDAVError(f"{method} {url} failed: {exc.reason}") from exc
-    except ValueError as exc:
+    except (OutboundHttpError, ValueError) as exc:
         raise CalDAVError(f"{method} {url} failed: {exc}") from exc
 
 
 def parse_multistatus(payload: bytes) -> CalDAVReportResult:
     try:
-        root = ElementTree.fromstring(payload)
+        root = SafeElementTree.fromstring(payload)
-    except ElementTree.ParseError as exc:
+    except SafeElementTree.ParseError as exc:
         raise CalDAVError(f"Invalid CalDAV XML response: {exc}") from exc
     objects: list[CalDAVObject] = []
     sync_token = first_child_text(root, "sync-token")
@@ -355,76 +422,167 @@ def parse_multistatus(payload: bytes) -> CalDAVReportResult:
 
 def parse_discovery_multistatus(payload: bytes) -> list[_DAVDiscoveryResponse]:
     try:
-        root = ElementTree.fromstring(payload)
+        root = SafeElementTree.fromstring(payload)
-    except ElementTree.ParseError as exc:
+    except SafeElementTree.ParseError as exc:
         raise CalDAVError(f"Invalid CalDAV XML response: {exc}") from exc
-    responses: list[_DAVDiscoveryResponse] = []
+    return [
-    for response in child_elements(root, "response"):
+        parsed
+        for response in child_elements(root, "response")
+        if (parsed := _parse_discovery_response(response)) is not None
+    ]
+
+
+def _parse_discovery_response(response: Any) -> _DAVDiscoveryResponse | None:
     href = first_child_text(response, "href")
     if not href:
-            continue
+        return None
-        display_name = None
+    draft = _DAVDiscoveryDraft()
-        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 ""
+        _apply_discovery_propstat(draft, propstat)
-            if status and " 200 " not in status and not status.endswith(" 200") and " 207 " not in status:
+    return _DAVDiscoveryResponse(
-                continue
+        href=href,
+        display_name=draft.display_name,
+        color=draft.color,
+        ctag=draft.ctag,
+        sync_token=draft.sync_token,
+        is_calendar=draft.is_calendar,
+        principal_hrefs=dedupe_tuple(draft.principal_hrefs),
+        calendar_home_set_hrefs=dedupe_tuple(draft.calendar_home_set_hrefs),
+        supported_components=dedupe_tuple(draft.supported_components),
+    )
+
+
+def _apply_discovery_propstat(draft: _DAVDiscoveryDraft, propstat: Any) -> None:
+    if not discovery_propstat_is_success(propstat):
+        return
     prop = first_child(propstat, "prop")
     if prop is None:
-                continue
+        return
     for item in prop:
+        _apply_discovery_property(draft, item)
+
+
+def discovery_propstat_is_success(propstat: Any) -> bool:
+    status = first_child_text(propstat, "status") or ""
+    return not status or " 200 " in status or status.endswith(" 200") or " 207 " in status
+
+
+def _apply_discovery_property(draft: _DAVDiscoveryDraft, item: Any) -> None:
     name = local_name(item.tag)
-                if name == "displayname" and item.text:
+    text = item.text.strip() if item.text else ""
-                    display_name = item.text.strip() or display_name
+    if name == "displayname" and text:
-                elif name == "calendar-color" and item.text:
+        draft.display_name = text or draft.display_name
-                    color = item.text.strip() or color
+    elif name == "calendar-color" and text:
-                elif name == "getctag" and item.text:
+        draft.color = text or draft.color
-                    ctag = item.text.strip() or ctag
+    elif name == "getctag" and text:
-                elif name == "sync-token" and item.text:
+        draft.ctag = text or draft.ctag
-                    sync_token = item.text.strip() or sync_token
+    elif name == "sync-token" and text:
+        draft.sync_token = text or draft.sync_token
     elif name == "resourcetype":
-                    is_calendar = is_calendar or any(local_name(child.tag) == "calendar" for child in item)
+        draft.is_calendar = draft.is_calendar or discovery_resource_is_calendar(item)
     elif name in {"current-user-principal", "principal-URL"}:
-                    principal_hrefs.extend(nested_href_texts(item))
+        draft.principal_hrefs.extend(nested_href_texts(item))
     elif name == "calendar-home-set":
-                    calendar_home_set_hrefs.extend(nested_href_texts(item))
+        draft.calendar_home_set_hrefs.extend(nested_href_texts(item))
     elif name == "supported-calendar-component-set":
+        draft.supported_components.extend(supported_calendar_component_names(item))
+
+
+def discovery_resource_is_calendar(item: Any) -> bool:
+    return any(local_name(child.tag) == "calendar" for child in item)
+
+
+def supported_calendar_component_names(item: Any) -> list[str]:
+    names: list[str] = []
     for component in item:
-                        if local_name(component.tag) == "comp":
+        if local_name(component.tag) != "comp":
+            continue
         component_name = (component.attrib.get("name") or "").strip().upper()
         if component_name:
-                                supported_components.append(component_name)
+            names.append(component_name)
-        responses.append(
+    return names
-            _DAVDiscoveryResponse(
+
-                href=href,
+
-                display_name=display_name,
+def dedupe_tuple(values: list[str]) -> tuple[str, ...]:
-                color=color,
+    return tuple(dict.fromkeys(values))
-                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}/"
+    url = validate_http_url(value)
+    return url if url.endswith("/") else f"{url}/"
+
+
+def validate_http_url(value: str) -> str:
+    parsed = urllib.parse.urlparse(value.strip())
+    if parsed.scheme.lower() not in {"http", "https"} or not parsed.netloc or not parsed.hostname:
+        raise CalDAVError("CalDAV URL must be an absolute HTTP(S) URL")
+    if parsed.username or parsed.password:
+        raise CalDAVError("CalDAV URL must not include embedded credentials")
+    if parsed.query or parsed.fragment:
+        raise CalDAVError("CalDAV URL must not include a query or fragment")
+    _url_origin(parsed)
+    return urllib.parse.urlunparse(parsed)
 
 
 def absolute_dav_url(base_url: str, href: str) -> str:
-    return urllib.parse.urljoin(ensure_collection_url(base_url), href)
+    return same_origin_dav_url(base_url, href, label="CalDAV discovery href")
+
+
+def same_origin_dav_url(base_url: str, href: str, *, label: str) -> str:
+    base = ensure_collection_url(base_url)
+    candidate = validate_http_url(urllib.parse.urljoin(base, href))
+    if _url_origin(urllib.parse.urlparse(candidate)) != _url_origin(urllib.parse.urlparse(base)):
+        raise CalDAVError(f"{label} must use the configured collection origin")
+    return candidate
+
+
+def _url_origin(parsed: urllib.parse.ParseResult) -> tuple[str, str, int]:
+    try:
+        port = parsed.port
+    except ValueError as exc:
+        raise CalDAVError("CalDAV URL has an invalid port") from exc
+    scheme = parsed.scheme.lower()
+    if port is None:
+        port = 443 if scheme == "https" else 80
+    return scheme, (parsed.hostname or "").lower(), port
+
+
+class _SameOriginRedirectHandler(urllib.request.HTTPRedirectHandler):
+    def __init__(self, source_url: str) -> None:
+        super().__init__()
+        self._source_origin = _url_origin(urllib.parse.urlparse(validate_http_url(source_url)))
+
+    def redirect_request(self, req, fp, code, msg, headers, newurl):  # type: ignore[no-untyped-def]
+        del fp, msg, headers
+        try:
+            candidate = validate_http_url(newurl)
+            candidate = validate_outbound_http_url(candidate, label="CalDAV redirect URL")
+        except (CalDAVError, OutboundHttpError):
+            return None
+        if _url_origin(urllib.parse.urlparse(candidate)) != self._source_origin:
+            return None
+        method = req.get_method()
+        data = req.data
+        if code == 303 and method != "HEAD":
+            method, data = "GET", None
+        elif code in {301, 302} and method == "POST":
+            method, data = "GET", None
+        forwarded_headers = {
+            key: value
+            for key, value in req.header_items()
+            if key.casefold() not in {"host", "content-length"}
+        }
+        return urllib.request.Request(  # noqa: S310 - candidate is validated and same-origin.
+            candidate,
+            data=data,
+            headers=forwarded_headers,
+            origin_req_host=req.origin_req_host,
+            unverifiable=True,
+            method=method,
+        )
 
 
 def strip_weak_etag(value: str | None) -> str | None:
@@ -444,25 +602,25 @@ def xml_escape(value: str) -> str:
     return value.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
 
 
-def first_child(element: ElementTree.Element, name: str) -> ElementTree.Element | None:
+def first_child(element: Any, name: str) -> Any | None:
     for child in element:
         if local_name(child.tag) == name:
             return child
     return None
 
 
-def first_child_text(element: ElementTree.Element, name: str) -> str | None:
+def first_child_text(element: Any, name: str) -> str | None:
     found = first_child(element, name)
     if found is None or found.text is None:
         return None
     return found.text.strip()
 
 
-def child_elements(element: ElementTree.Element, name: str) -> list[ElementTree.Element]:
+def child_elements(element: Any, name: str) -> list[Any]:
     return [child for child in element if local_name(child.tag) == name]
 
 
-def nested_href_texts(element: ElementTree.Element) -> list[str]:
+def nested_href_texts(element: Any) -> list[str]:
     hrefs: list[str] = []
     for child in element.iter():
         if local_name(child.tag) == "href" and child.text and child.text.strip():

src/govoplan_calendar/backend/capabilities.py

@@ -0,0 +1,82 @@
+from __future__ import annotations
+
+from collections.abc import Mapping, Sequence
+from datetime import datetime
+
+from govoplan_core.core.calendar import (
+    CalendarCapabilityError,
+    CalendarEventRef,
+    CalendarEventRequest,
+    CalendarSchedulingProvider,
+)
+from govoplan_calendar.backend.schemas import CalendarEventCreateRequest
+from govoplan_calendar.backend.service import CalendarError, create_event, list_freebusy
+
+
+class SqlCalendarSchedulingProvider(CalendarSchedulingProvider):
+    def list_freebusy(
+        self,
+        session: object,
+        *,
+        tenant_id: str,
+        start_at: datetime,
+        end_at: datetime,
+        calendar_ids: Sequence[str] | None = None,
+    ) -> tuple[Mapping[str, object], ...]:
+        try:
+            blocks = list_freebusy(
+                session,
+                tenant_id=tenant_id,
+                start_at=start_at,
+                end_at=end_at,
+                calendar_ids=list(calendar_ids) if calendar_ids is not None else None,
+            )
+        except CalendarError as exc:
+            raise CalendarCapabilityError(str(exc)) from exc
+        return tuple(blocks)
+
+    def create_event(
+        self,
+        session: object,
+        *,
+        tenant_id: str,
+        user_id: str | None,
+        request: CalendarEventRequest,
+    ) -> CalendarEventRef:
+        try:
+            payload = CalendarEventCreateRequest(
+                calendar_id=request.calendar_id,
+                summary=request.summary,
+                description=request.description,
+                location=request.location,
+                status=request.status,
+                transparency=request.transparency,
+                classification=request.classification,
+                start_at=request.start_at,
+                end_at=request.end_at,
+                timezone=request.timezone,
+                attendees=[dict(item) for item in request.attendees],
+                categories=list(request.categories),
+                related_to=[dict(item) for item in request.related_to],
+                metadata=dict(request.metadata),
+            )
+        except (TypeError, ValueError) as exc:
+            raise CalendarCapabilityError(str(exc)) from exc
+        try:
+            event = create_event(session, tenant_id=tenant_id, user_id=user_id, payload=payload)
+        except CalendarError as exc:
+            raise CalendarCapabilityError(str(exc)) from exc
+        caldav_metadata = (event.metadata_ or {}).get("caldav")
+        external_state = "local"
+        outbox_operation_id = None
+        if isinstance(caldav_metadata, dict):
+            external_state = str(caldav_metadata.get("external_state") or "queued")
+            raw_operation_id = caldav_metadata.get("outbox_operation_id")
+            outbox_operation_id = str(raw_operation_id) if raw_operation_id else None
+        return CalendarEventRef(
+            id=event.id,
+            calendar_id=event.calendar_id,
+            uid=event.uid,
+            external_state=external_state,
+            outbox_operation_id=outbox_operation_id,
+        )

src/govoplan_calendar/backend/db/models.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import uuid
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Any
 
 from sqlalchemy import Boolean, DateTime, ForeignKey, Index, Integer, JSON, String, Text, UniqueConstraint, text
@@ -151,4 +151,69 @@ class CalendarSyncCredential(Base, TimestampMixin):
     metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
 
 
-__all__ = ["CalendarCollection", "CalendarEvent", "CalendarSyncCredential", "CalendarSyncSource", "new_uuid"]
+class CalendarOutboxOperation(Base, TimestampMixin):
+    """Durable desired state for one external CalDAV resource.
+
+    Rows are inserted in the same transaction as the local event mutation.  A
+    dispatcher leases and commits the row before performing network I/O, so a
+    worker crash can be detected and reconciled without repeating a blind
+    write.
+    """
+
+    __tablename__ = "calendar_outbox_operations"
+    __table_args__ = (
+        UniqueConstraint("idempotency_key", name="uq_calendar_outbox_operations_idempotency_key"),
+        Index("ix_calendar_outbox_due", "status", "available_at", "created_at"),
+        Index("ix_calendar_outbox_tenant_status", "tenant_id", "status"),
+        Index("ix_calendar_outbox_resource", "source_id", "resource_href", "created_at"),
+        Index("ix_calendar_outbox_lease", "status", "lease_expires_at"),
+    )
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
+    source_id: Mapped[str] = mapped_column(
+        ForeignKey("calendar_sync_sources.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    event_id: Mapped[str | None] = mapped_column(
+        ForeignKey("calendar_events.id", ondelete="SET NULL"),
+        nullable=True,
+        index=True,
+    )
+    operation_kind: Mapped[str] = mapped_column(String(20), nullable=False, index=True)
+    resource_href: Mapped[str] = mapped_column(String(1000), nullable=False)
+    payload_ics: Mapped[str | None] = mapped_column(Text)
+    payload_fingerprint: Mapped[str | None] = mapped_column(String(64), nullable=True, index=True)
+    expected_etag: Mapped[str | None] = mapped_column(String(255))
+    idempotency_key: Mapped[str] = mapped_column(String(64), nullable=False)
+    status: Mapped[str] = mapped_column(String(30), default="pending", nullable=False, index=True)
+    attempt_count: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
+    max_attempts: Mapped[int] = mapped_column(Integer, default=8, nullable=False)
+    available_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=lambda: datetime.now(timezone.utc),
+        nullable=False,
+        index=True,
+    )
+    last_attempt_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    lease_token: Mapped[str | None] = mapped_column(String(36), nullable=True, index=True)
+    lease_expires_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
+    completed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    reconciled_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    remote_etag: Mapped[str | None] = mapped_column(String(255))
+    last_error: Mapped[str | None] = mapped_column(Text)
+    metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
+
+    source: Mapped[CalendarSyncSource] = relationship()
+    event: Mapped[CalendarEvent | None] = relationship()
+
+
+__all__ = [
+    "CalendarCollection",
+    "CalendarEvent",
+    "CalendarOutboxOperation",
+    "CalendarSyncCredential",
+    "CalendarSyncSource",
+    "new_uuid",
+]

src/govoplan_calendar/backend/ical.py

@@ -153,6 +153,18 @@ def events_to_ics(events: list[Any]) -> str:
 
 def event_to_component(event: Any) -> Event:
     component = Event()
+    add_event_identity_and_time(component, event)
+    add_event_status_fields(component, event)
+    add_event_optional_text_fields(component, event)
+    add_event_recurrence_and_parties(component, event)
+    add_event_raw_records(component, event)
+    add_preserved_properties(component, getattr(event, "icalendar", None) or {})
+    for alarm in alarms_for_export(event):
+        component.add_component(alarm)
+    return component
+
+
+def add_event_identity_and_time(component: Event, event: Any) -> None:
     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))
@@ -164,23 +176,35 @@ def event_to_component(event: Any) -> Event:
         component.add("duration", timedelta(seconds=int(event.duration_seconds)))
     if getattr(event, "recurrence_id", None):
         add_recurrence_id(component, str(event.recurrence_id))
+
+
+def add_event_status_fields(component: Event, event: Any) -> None:
     component.add("summary", event.summary)
     component.add("sequence", int(event.sequence or 0))
     component.add("status", event.status)
     component.add("transp", event.transparency)
     component.add("class", event.classification)
+
+
+def add_event_optional_text_fields(component: Event, event: Any) -> None:
     if event.description:
         component.add("description", event.description)
     if event.location:
         component.add("location", event.location)
     if event.categories:
         component.add("categories", list(event.categories))
+
+
+def add_event_recurrence_and_parties(component: Event, event: Any) -> None:
     if event.rrule:
         component.add("rrule", normalized_rrule_for_export(event.rrule))
     if event.organizer:
         component.add("organizer", party_for_export(event.organizer))
     for attendee in event.attendees or []:
         component.add("attendee", party_for_export(attendee))
+
+
+def add_event_raw_records(component: Event, event: Any) -> None:
     for record in getattr(event, "rdate", None) or []:
         add_raw_property(component, "RDATE", record)
     for record in getattr(event, "exdate", None) or []:
@@ -190,11 +214,6 @@ def event_to_component(event: Any) -> Event:
     for record in getattr(event, "related_to", None) or []:
         add_raw_property(component, "RELATED-TO", record)
 
-    add_preserved_properties(component, getattr(event, "icalendar", None) or {})
-    for alarm in alarms_for_export(event):
-        component.add_component(alarm)
-    return component
-
 
 def expand_event_occurrences(event: Any, range_start: datetime, range_end: datetime, *, limit: int = 1000) -> list[dict[str, Any]]:
     """Expand an event's recurrence primitives within a range.

src/govoplan_calendar/backend/manifest.py

@@ -1,14 +1,68 @@
 from __future__ import annotations
 
+from dataclasses import replace
 from pathlib import Path
 
+from sqlalchemy import inspect
+
 from govoplan_calendar.backend.db import models as calendar_models  # noqa: F401 - populate Calendar ORM metadata
 from govoplan_core.core.access import CAPABILITY_AUTH_PERMISSION_EVALUATOR, CAPABILITY_AUTH_PRINCIPAL_RESOLVER
+from govoplan_core.core.calendar import (
+    CALENDAR_AVAILABILITY_READ_SCOPE,
+    CALENDAR_EVENT_WRITE_SCOPE,
+    CAPABILITY_CALENDAR_OUTBOX,
+    CAPABILITY_CALENDAR_SCHEDULING,
+)
 from govoplan_core.core.module_guards import drop_table_retirement_provider, persistent_table_uninstall_guard
-from govoplan_core.core.modules import FrontendModule, MigrationSpec, ModuleContext, ModuleManifest, NavItem, PermissionDefinition, RoleTemplate
+from govoplan_core.core.modules import (
+    FrontendModule,
+    FrontendRoute,
+    MigrationSpec,
+    ModuleContext,
+    ModuleInterfaceProvider,
+    ModuleManifest,
+    NavItem,
+    PermissionDefinition,
+    RoleTemplate,
+)
 from govoplan_core.db.base import Base
 
 
+_calendar_table_retirement_provider = drop_table_retirement_provider(
+    calendar_models.CalendarCollection,
+    calendar_models.CalendarEvent,
+    calendar_models.CalendarOutboxOperation,
+    calendar_models.CalendarSyncCredential,
+    calendar_models.CalendarSyncSource,
+    label="Calendar",
+)
+
+
+def _calendar_retirement_provider(session: object | None, module_id: str):
+    plan = _calendar_table_retirement_provider(session, module_id)
+    base_executor = plan.destroy_data_executor
+    if base_executor is None:
+        return plan
+
+    def executor(execute_session: object, execute_module_id: str) -> None:
+        if not hasattr(execute_session, "get_bind") or not hasattr(execute_session, "query"):
+            raise RuntimeError("No database session is available for Calendar credential retirement.")
+        if inspect(execute_session.get_bind()).has_table(calendar_models.CalendarSyncCredential.__tablename__):
+            from govoplan_calendar.backend.service import delete_calendar_credentials_for_retirement
+
+            delete_calendar_credentials_for_retirement(execute_session)
+        base_executor(execute_session, execute_module_id)
+
+    return replace(
+        plan,
+        destroy_data_warnings=(
+            *plan.destroy_data_warnings,
+            "Calendar-owned credentials are deleted immediately before tables are dropped; retirement fails if an external secret provider is unavailable.",
+        ),
+        destroy_data_executor=executor,
+    )
+
+
 def _permission(scope: str, label: str, description: str) -> PermissionDefinition:
     module_id, resource, action = scope.split(":", 2)
     return PermissionDefinition(
@@ -28,11 +82,11 @@ PERMISSIONS = (
     _permission("calendar:calendar:write", "Manage calendars", "Create and edit tenant calendar collections."),
     _permission("calendar:calendar:admin", "Administer calendars", "Delete calendars and manage tenant-level calendar settings."),
     _permission("calendar:event:read", "View calendar events", "List and inspect calendar events."),
-    _permission("calendar:event:write", "Manage calendar events", "Create and edit calendar events."),
+    _permission(CALENDAR_EVENT_WRITE_SCOPE, "Manage calendar events", "Create and edit calendar events."),
     _permission("calendar:event:delete", "Delete calendar events", "Delete or cancel calendar events where policy allows it."),
     _permission("calendar:event:import", "Import iCalendar events", "Import VEVENT data from iCalendar sources."),
     _permission("calendar:event:export", "Export iCalendar events", "Export events as text/calendar VEVENT data."),
-    _permission("calendar:availability:read", "Read availability", "Read free/busy and availability data for integrations."),
+    _permission(CALENDAR_AVAILABILITY_READ_SCOPE, "Read availability", "Read free/busy and availability data for integrations."),
 )
 
 ROLE_TEMPLATES = (
@@ -44,11 +98,11 @@ ROLE_TEMPLATES = (
             "calendar:calendar:read",
             "calendar:calendar:write",
             "calendar:event:read",
-            "calendar:event:write",
+            CALENDAR_EVENT_WRITE_SCOPE,
             "calendar:event:delete",
             "calendar:event:import",
             "calendar:event:export",
-            "calendar:availability:read",
+            CALENDAR_AVAILABILITY_READ_SCOPE,
         ),
     ),
     RoleTemplate(
@@ -59,20 +113,32 @@ ROLE_TEMPLATES = (
             "calendar:calendar:read",
             "calendar:event:read",
             "calendar:event:export",
-            "calendar:availability:read",
+            CALENDAR_AVAILABILITY_READ_SCOPE,
         ),
     ),
 )
 
 
 def _tenant_summary(session, tenant_id: str) -> dict[str, int]:
-    from govoplan_calendar.backend.db.models import CalendarCollection, CalendarEvent, CalendarSyncCredential, CalendarSyncSource
+    from govoplan_calendar.backend.db.models import (
+        CalendarCollection,
+        CalendarEvent,
+        CalendarOutboxOperation,
+        CalendarSyncCredential,
+        CalendarSyncSource,
+    )
 
     return {
         "calendars": session.query(CalendarCollection).filter(CalendarCollection.tenant_id == tenant_id, CalendarCollection.deleted_at.is_(None)).count(),
         "calendar_events": session.query(CalendarEvent).filter(CalendarEvent.tenant_id == tenant_id, CalendarEvent.deleted_at.is_(None)).count(),
         "calendar_sync_sources": session.query(CalendarSyncSource).filter(CalendarSyncSource.tenant_id == tenant_id, CalendarSyncSource.deleted_at.is_(None)).count(),
         "calendar_sync_credentials": session.query(CalendarSyncCredential).filter(CalendarSyncCredential.tenant_id == tenant_id, CalendarSyncCredential.deleted_at.is_(None)).count(),
+        "calendar_outbox_pending": session.query(CalendarOutboxOperation)
+        .filter(
+            CalendarOutboxOperation.tenant_id == tenant_id,
+            CalendarOutboxOperation.status.in_(("pending", "retry", "in_progress")),
+        )
+        .count(),
     }
 
 
@@ -85,20 +151,58 @@ def _calendar_router(context: ModuleContext):
     return router
 
 
+def _calendar_scheduling_provider(context: ModuleContext) -> object:
+    del context
+    from govoplan_calendar.backend.capabilities import SqlCalendarSchedulingProvider
+
+    return SqlCalendarSchedulingProvider()
+
+
+def _calendar_outbox_provider(context: ModuleContext) -> object:
+    from govoplan_calendar.backend.outbox import (
+        OUTBOX_DEFAULT_TERMINAL_RETENTION_DAYS,
+        SqlCalendarOutboxProvider,
+    )
+
+    return SqlCalendarOutboxProvider(
+        terminal_retention_days=getattr(
+            context.settings,
+            "calendar_outbox_terminal_retention_days",
+            OUTBOX_DEFAULT_TERMINAL_RETENTION_DAYS,
+        )
+    )
+
+
 manifest = ModuleManifest(
     id="calendar",
     name="Calendar",
-    version="0.1.6",
+    version="0.1.8",
     required_capabilities=(CAPABILITY_AUTH_PRINCIPAL_RESOLVER, CAPABILITY_AUTH_PERMISSION_EVALUATOR),
     optional_dependencies=("mail", "tasks", "scheduling", "appointments", "workflow", "notifications", "dms", "connectors"),
+    provides_interfaces=(
+        ModuleInterfaceProvider(name="calendar.outbox", version="0.1.8"),
+        ModuleInterfaceProvider(name="calendar.scheduling", version="0.1.8"),
+    ),
     permissions=PERMISSIONS,
     route_factory=_calendar_router,
     role_templates=ROLE_TEMPLATES,
     tenant_summary_providers=(_tenant_summary,),
+    capability_factories={
+        CAPABILITY_CALENDAR_OUTBOX: _calendar_outbox_provider,
+        CAPABILITY_CALENDAR_SCHEDULING: _calendar_scheduling_provider,
+    },
     nav_items=(NavItem(path="/calendar", label="Calendar", icon="calendar", required_any=("calendar:event:read",), order=55),),
     frontend=FrontendModule(
         module_id="calendar",
         package_name="@govoplan/calendar-webui",
+        routes=(
+            FrontendRoute(
+                path="/calendar",
+                component="CalendarPage",
+                required_any=("calendar:event:read",),
+                order=55,
+            ),
+        ),
         nav_items=(NavItem(path="/calendar", label="Calendar", icon="calendar", required_any=("calendar:event:read",), order=55),),
     ),
     migration_spec=MigrationSpec(
@@ -106,19 +210,14 @@ manifest = ModuleManifest(
         metadata=Base.metadata,
         script_location=str(Path(__file__).with_name("migrations") / "versions"),
         retirement_supported=True,
-        retirement_provider=drop_table_retirement_provider(
+        retirement_provider=_calendar_retirement_provider,
-            calendar_models.CalendarCollection,
-            calendar_models.CalendarEvent,
-            calendar_models.CalendarSyncCredential,
-            calendar_models.CalendarSyncSource,
-            label="Calendar",
-        ),
         retirement_notes="Destructive retirement drops calendar-owned database tables after the installer captures a database snapshot.",
     ),
     uninstall_guard_providers=(
         persistent_table_uninstall_guard(
             calendar_models.CalendarCollection,
             calendar_models.CalendarEvent,
+            calendar_models.CalendarOutboxOperation,
             calendar_models.CalendarSyncCredential,
             calendar_models.CalendarSyncSource,
             label="Calendar",

src/govoplan_calendar/backend/migrations/dev_versions/__init__.py

@@ -0,0 +1 @@
+"""Calendar Alembic revisions."""

src/govoplan_calendar/backend/migrations/dev_versions/af1b2c3d4e5f_calendar_caldav_outbox.py

@@ -0,0 +1,28 @@
+"""Add the durable CalDAV desired-state outbox on the development track.
+
+Revision ID: af1b2c3d4e5f
+Revises: 9e0f1a2b3c4d
+Create Date: 2026-07-20 00:00:00.000000
+"""
+from __future__ import annotations
+
+from govoplan_calendar.backend.migrations.versions.af1b2c3d4e5f_calendar_caldav_outbox import (
+    downgrade as _downgrade,
+)
+from govoplan_calendar.backend.migrations.versions.af1b2c3d4e5f_calendar_caldav_outbox import (
+    upgrade as _upgrade,
+)
+
+
+revision = "af1b2c3d4e5f"
+down_revision = "9e0f1a2b3c4d"
+branch_labels = None
+depends_on = "4f2a9c8e7b6d"
+
+
+def upgrade() -> None:
+    _upgrade()
+
+
+def downgrade() -> None:
+    _downgrade()

src/govoplan_calendar/backend/migrations/versions/9e0f1a2b3c4d_v017_calendar_baseline.py

@@ -0,0 +1,174 @@
+"""v0.1.7 calendar baseline
+
+Revision ID: 9e0f1a2b3c4d
+Revises: None
+Create Date: 2026-07-11 00:00:00.000000
+"""
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = '9e0f1a2b3c4d'
+down_revision = None
+branch_labels = None
+depends_on = '4f2a9c8e7b6d'
+
+
+def upgrade() -> None:
+    op.create_table('calendar_collections',
+    sa.Column('id', sa.String(length=36), nullable=False),
+    sa.Column('tenant_id', sa.String(length=36), nullable=False),
+    sa.Column('slug', sa.String(length=100), nullable=False),
+    sa.Column('name', sa.String(length=255), nullable=False),
+    sa.Column('description', sa.Text(), nullable=True),
+    sa.Column('timezone', sa.String(length=100), nullable=False),
+    sa.Column('color', sa.String(length=20), nullable=True),
+    sa.Column('owner_type', sa.String(length=20), nullable=False),
+    sa.Column('owner_id', sa.String(length=36), nullable=True),
+    sa.Column('visibility', sa.String(length=20), nullable=False),
+    sa.Column('is_default', sa.Boolean(), nullable=False),
+    sa.Column('created_by_user_id', sa.String(length=36), nullable=True),
+    sa.Column('deleted_at', sa.DateTime(timezone=True), nullable=True),
+    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'], ['access_users.id'], name=op.f('fk_calendar_collections_created_by_user_id_access_users'), ondelete='SET NULL'),
+    sa.ForeignKeyConstraint(['tenant_id'], ['core_scopes.id'], name=op.f('fk_calendar_collections_tenant_id_scopes'), ondelete='CASCADE'),
+    sa.PrimaryKeyConstraint('id', name=op.f('pk_calendar_collections'))
+    )
+    op.create_index(op.f('ix_calendar_collections_created_by_user_id'), 'calendar_collections', ['created_by_user_id'], unique=False)
+    op.create_index(op.f('ix_calendar_collections_deleted_at'), 'calendar_collections', ['deleted_at'], unique=False)
+    op.create_index(op.f('ix_calendar_collections_is_default'), 'calendar_collections', ['is_default'], unique=False)
+    op.create_index('ix_calendar_collections_owner', 'calendar_collections', ['tenant_id', 'owner_type', 'owner_id'], unique=False)
+    op.create_index(op.f('ix_calendar_collections_owner_id'), 'calendar_collections', ['owner_id'], unique=False)
+    op.create_index(op.f('ix_calendar_collections_owner_type'), 'calendar_collections', ['owner_type'], unique=False)
+    op.create_index(op.f('ix_calendar_collections_tenant_id'), 'calendar_collections', ['tenant_id'], unique=False)
+    op.create_index(op.f('ix_calendar_collections_visibility'), 'calendar_collections', ['visibility'], unique=False)
+    op.create_index('uq_calendar_collections_active_slug', 'calendar_collections', ['tenant_id', 'slug'], unique=True, sqlite_where=sa.text('deleted_at IS NULL'), postgresql_where=sa.text('deleted_at IS NULL'))
+    op.create_table('calendar_sync_credentials',
+    sa.Column('id', sa.String(length=36), nullable=False),
+    sa.Column('tenant_id', sa.String(length=36), nullable=False),
+    sa.Column('credential_kind', sa.String(length=30), nullable=False),
+    sa.Column('label', sa.String(length=255), nullable=True),
+    sa.Column('secret_encrypted', sa.Text(), nullable=True),
+    sa.Column('created_by_user_id', sa.String(length=36), nullable=True),
+    sa.Column('deleted_at', sa.DateTime(timezone=True), nullable=True),
+    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'], ['access_users.id'], name=op.f('fk_calendar_sync_credentials_created_by_user_id_access_users'), ondelete='SET NULL'),
+    sa.ForeignKeyConstraint(['tenant_id'], ['core_scopes.id'], name=op.f('fk_calendar_sync_credentials_tenant_id_scopes'), ondelete='CASCADE'),
+    sa.PrimaryKeyConstraint('id', name=op.f('pk_calendar_sync_credentials'))
+    )
+    op.create_index(op.f('ix_calendar_sync_credentials_created_by_user_id'), 'calendar_sync_credentials', ['created_by_user_id'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_credentials_credential_kind'), 'calendar_sync_credentials', ['credential_kind'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_credentials_deleted_at'), 'calendar_sync_credentials', ['deleted_at'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_credentials_tenant_id'), 'calendar_sync_credentials', ['tenant_id'], unique=False)
+    op.create_index('ix_calendar_sync_credentials_tenant_kind', 'calendar_sync_credentials', ['tenant_id', 'credential_kind'], unique=False)
+    op.create_table('calendar_events',
+    sa.Column('id', sa.String(length=36), nullable=False),
+    sa.Column('tenant_id', sa.String(length=36), nullable=False),
+    sa.Column('calendar_id', sa.String(length=36), nullable=False),
+    sa.Column('uid', sa.String(length=255), nullable=False),
+    sa.Column('recurrence_id', sa.String(length=255), nullable=True),
+    sa.Column('sequence', sa.Integer(), nullable=False),
+    sa.Column('summary', sa.String(length=500), nullable=False),
+    sa.Column('description', sa.Text(), nullable=True),
+    sa.Column('location', sa.String(length=500), nullable=True),
+    sa.Column('status', sa.String(length=40), nullable=False),
+    sa.Column('transparency', sa.String(length=20), nullable=False),
+    sa.Column('classification', sa.String(length=20), nullable=False),
+    sa.Column('start_at', sa.DateTime(timezone=True), nullable=False),
+    sa.Column('end_at', sa.DateTime(timezone=True), nullable=True),
+    sa.Column('duration_seconds', sa.Integer(), nullable=True),
+    sa.Column('all_day', sa.Boolean(), nullable=False),
+    sa.Column('timezone', sa.String(length=100), nullable=True),
+    sa.Column('organizer', sa.JSON(), nullable=True),
+    sa.Column('attendees', sa.JSON(), nullable=False),
+    sa.Column('categories', sa.JSON(), nullable=False),
+    sa.Column('rrule', sa.JSON(), nullable=True),
+    sa.Column('rdate', sa.JSON(), nullable=False),
+    sa.Column('exdate', sa.JSON(), nullable=False),
+    sa.Column('reminders', sa.JSON(), nullable=False),
+    sa.Column('attachments', sa.JSON(), nullable=False),
+    sa.Column('related_to', sa.JSON(), nullable=False),
+    sa.Column('source_kind', sa.String(length=30), nullable=False),
+    sa.Column('source_href', sa.String(length=1000), nullable=True),
+    sa.Column('etag', sa.String(length=255), nullable=True),
+    sa.Column('icalendar', sa.JSON(), nullable=False),
+    sa.Column('raw_ics', sa.Text(), nullable=True),
+    sa.Column('created_by_user_id', sa.String(length=36), nullable=True),
+    sa.Column('updated_by_user_id', sa.String(length=36), nullable=True),
+    sa.Column('deleted_at', sa.DateTime(timezone=True), nullable=True),
+    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(['calendar_id'], ['calendar_collections.id'], name=op.f('fk_calendar_events_calendar_id_calendar_collections'), ondelete='CASCADE'),
+    sa.ForeignKeyConstraint(['created_by_user_id'], ['access_users.id'], name=op.f('fk_calendar_events_created_by_user_id_access_users'), ondelete='SET NULL'),
+    sa.ForeignKeyConstraint(['tenant_id'], ['core_scopes.id'], name=op.f('fk_calendar_events_tenant_id_scopes'), ondelete='CASCADE'),
+    sa.ForeignKeyConstraint(['updated_by_user_id'], ['access_users.id'], name=op.f('fk_calendar_events_updated_by_user_id_access_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')
+    )
+    op.create_index(op.f('ix_calendar_events_all_day'), 'calendar_events', ['all_day'], unique=False)
+    op.create_index(op.f('ix_calendar_events_calendar_id'), 'calendar_events', ['calendar_id'], unique=False)
+    op.create_index(op.f('ix_calendar_events_created_by_user_id'), 'calendar_events', ['created_by_user_id'], unique=False)
+    op.create_index(op.f('ix_calendar_events_deleted_at'), 'calendar_events', ['deleted_at'], unique=False)
+    op.create_index(op.f('ix_calendar_events_end_at'), 'calendar_events', ['end_at'], unique=False)
+    op.create_index(op.f('ix_calendar_events_etag'), 'calendar_events', ['etag'], unique=False)
+    op.create_index('ix_calendar_events_range', 'calendar_events', ['tenant_id', 'calendar_id', 'start_at', 'end_at'], unique=False)
+    op.create_index(op.f('ix_calendar_events_recurrence_id'), 'calendar_events', ['recurrence_id'], unique=False)
+    op.create_index(op.f('ix_calendar_events_source_kind'), 'calendar_events', ['source_kind'], unique=False)
+    op.create_index(op.f('ix_calendar_events_start_at'), 'calendar_events', ['start_at'], unique=False)
+    op.create_index(op.f('ix_calendar_events_status'), 'calendar_events', ['status'], unique=False)
+    op.create_index(op.f('ix_calendar_events_tenant_id'), 'calendar_events', ['tenant_id'], unique=False)
+    op.create_index('ix_calendar_events_tenant_status', 'calendar_events', ['tenant_id', 'status'], unique=False)
+    op.create_index('ix_calendar_events_tenant_uid', 'calendar_events', ['tenant_id', 'uid'], unique=False)
+    op.create_index(op.f('ix_calendar_events_uid'), 'calendar_events', ['uid'], unique=False)
+    op.create_index(op.f('ix_calendar_events_updated_by_user_id'), 'calendar_events', ['updated_by_user_id'], unique=False)
+    op.create_table('calendar_sync_sources',
+    sa.Column('id', sa.String(length=36), nullable=False),
+    sa.Column('tenant_id', sa.String(length=36), nullable=False),
+    sa.Column('calendar_id', sa.String(length=36), nullable=False),
+    sa.Column('source_kind', sa.String(length=30), nullable=False),
+    sa.Column('collection_url', sa.String(length=1000), nullable=False),
+    sa.Column('display_name', sa.String(length=255), nullable=True),
+    sa.Column('auth_type', sa.String(length=30), nullable=False),
+    sa.Column('username', sa.String(length=255), nullable=True),
+    sa.Column('credential_ref', sa.String(length=255), nullable=True),
+    sa.Column('sync_enabled', sa.Boolean(), nullable=False),
+    sa.Column('sync_interval_seconds', sa.Integer(), nullable=False),
+    sa.Column('sync_direction', sa.String(length=30), nullable=False),
+    sa.Column('conflict_policy', sa.String(length=30), nullable=False),
+    sa.Column('sync_token', sa.Text(), nullable=True),
+    sa.Column('ctag', sa.String(length=255), nullable=True),
+    sa.Column('last_attempt_at', sa.DateTime(timezone=True), nullable=True),
+    sa.Column('last_synced_at', sa.DateTime(timezone=True), nullable=True),
+    sa.Column('next_sync_at', sa.DateTime(timezone=True), nullable=True),
+    sa.Column('last_status', sa.String(length=30), nullable=True),
+    sa.Column('last_error', sa.Text(), nullable=True),
+    sa.Column('deleted_at', sa.DateTime(timezone=True), nullable=True),
+    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(['calendar_id'], ['calendar_collections.id'], name=op.f('fk_calendar_sync_sources_calendar_id_calendar_collections'), ondelete='CASCADE'),
+    sa.ForeignKeyConstraint(['tenant_id'], ['core_scopes.id'], name=op.f('fk_calendar_sync_sources_tenant_id_scopes'), ondelete='CASCADE'),
+    sa.PrimaryKeyConstraint('id', name=op.f('pk_calendar_sync_sources'))
+    )
+    op.create_index('ix_calendar_sync_sources_calendar', 'calendar_sync_sources', ['tenant_id', 'calendar_id', 'source_kind'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_sources_calendar_id'), 'calendar_sync_sources', ['calendar_id'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_sources_deleted_at'), 'calendar_sync_sources', ['deleted_at'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_sources_next_sync_at'), 'calendar_sync_sources', ['next_sync_at'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_sources_source_kind'), 'calendar_sync_sources', ['source_kind'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_sources_sync_enabled'), 'calendar_sync_sources', ['sync_enabled'], unique=False)
+    op.create_index(op.f('ix_calendar_sync_sources_tenant_id'), 'calendar_sync_sources', ['tenant_id'], unique=False)
+    op.create_index('uq_calendar_sync_sources_active_url', 'calendar_sync_sources', ['tenant_id', 'source_kind', 'collection_url'], unique=True, sqlite_where=sa.text('deleted_at IS NULL'), postgresql_where=sa.text('deleted_at IS NULL'))
+
+
+def downgrade() -> None:
+    op.drop_table('calendar_sync_sources')
+    op.drop_table('calendar_events')
+    op.drop_table('calendar_sync_credentials')
+    op.drop_table('calendar_collections')

src/govoplan_calendar/backend/migrations/versions/af1b2c3d4e5f_calendar_caldav_outbox.py

@@ -0,0 +1,114 @@
+"""Add the durable CalDAV desired-state outbox.
+
+Revision ID: af1b2c3d4e5f
+Revises: 9e0f1a2b3c4d
+Create Date: 2026-07-20 00:00:00.000000
+"""
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "af1b2c3d4e5f"
+down_revision = "9e0f1a2b3c4d"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "calendar_outbox_operations",
+        sa.Column("id", sa.String(length=36), nullable=False),
+        sa.Column("tenant_id", sa.String(length=36), nullable=False),
+        sa.Column("source_id", sa.String(length=36), nullable=False),
+        sa.Column("event_id", sa.String(length=36), nullable=True),
+        sa.Column("operation_kind", sa.String(length=20), nullable=False),
+        sa.Column("resource_href", sa.String(length=1000), nullable=False),
+        sa.Column("payload_ics", sa.Text(), nullable=True),
+        sa.Column("payload_fingerprint", sa.String(length=64), nullable=True),
+        sa.Column("expected_etag", sa.String(length=255), nullable=True),
+        sa.Column("idempotency_key", sa.String(length=64), nullable=False),
+        sa.Column("status", sa.String(length=30), nullable=False),
+        sa.Column("attempt_count", sa.Integer(), nullable=False),
+        sa.Column("max_attempts", sa.Integer(), nullable=False),
+        sa.Column("available_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("last_attempt_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("lease_token", sa.String(length=36), nullable=True),
+        sa.Column("lease_expires_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("completed_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("reconciled_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("remote_etag", sa.String(length=255), nullable=True),
+        sa.Column("last_error", sa.Text(), nullable=True),
+        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(
+            ["event_id"],
+            ["calendar_events.id"],
+            name=op.f("fk_calendar_outbox_operations_event_id_calendar_events"),
+            ondelete="SET NULL",
+        ),
+        sa.ForeignKeyConstraint(
+            ["source_id"],
+            ["calendar_sync_sources.id"],
+            name=op.f("fk_calendar_outbox_operations_source_id_calendar_sync_sources"),
+            ondelete="CASCADE",
+        ),
+        sa.ForeignKeyConstraint(
+            ["tenant_id"],
+            ["core_scopes.id"],
+            name=op.f("fk_calendar_outbox_operations_tenant_id_scopes"),
+            ondelete="CASCADE",
+        ),
+        sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_outbox_operations")),
+        sa.UniqueConstraint(
+            "idempotency_key",
+            name="uq_calendar_outbox_operations_idempotency_key",
+        ),
+    )
+    op.create_index(
+        "ix_calendar_outbox_due",
+        "calendar_outbox_operations",
+        ["status", "available_at", "created_at"],
+        unique=False,
+    )
+    op.create_index(
+        "ix_calendar_outbox_lease",
+        "calendar_outbox_operations",
+        ["status", "lease_expires_at"],
+        unique=False,
+    )
+    op.create_index(
+        "ix_calendar_outbox_resource",
+        "calendar_outbox_operations",
+        ["source_id", "resource_href", "created_at"],
+        unique=False,
+    )
+    op.create_index(
+        "ix_calendar_outbox_tenant_status",
+        "calendar_outbox_operations",
+        ["tenant_id", "status"],
+        unique=False,
+    )
+    for column in (
+        "available_at",
+        "event_id",
+        "lease_expires_at",
+        "lease_token",
+        "operation_kind",
+        "payload_fingerprint",
+        "source_id",
+        "status",
+        "tenant_id",
+    ):
+        op.create_index(
+            op.f(f"ix_calendar_outbox_operations_{column}"),
+            "calendar_outbox_operations",
+            [column],
+            unique=False,
+        )
+
+
+def downgrade() -> None:
+    op.drop_table("calendar_outbox_operations")

src/govoplan_calendar/backend/router.py

@@ -7,6 +7,7 @@ from sqlalchemy.orm import Session
 
 from govoplan_core.auth import ApiPrincipal, get_api_principal, has_scope
 from govoplan_core.api.v1.schemas import DeltaDeletedItem
+from govoplan_core.core.calendar import CALENDAR_AVAILABILITY_READ_SCOPE, CALENDAR_EVENT_WRITE_SCOPE
 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
@@ -27,6 +28,8 @@ from govoplan_calendar.backend.schemas import (
     CalendarCollectionListResponse,
     CalendarCollectionResponse,
     CalendarCollectionUpdateRequest,
+    CalendarCredentialEnvelopeListResponse,
+    CalendarCredentialEnvelopeResponse,
     CalendarEventCreateRequest,
     CalendarEventDeltaResponse,
     CalendarEventListResponse,
@@ -35,6 +38,9 @@ from govoplan_calendar.backend.schemas import (
     CalendarFreeBusyRequest,
     CalendarFreeBusyResponse,
     CalendarIcsImportRequest,
+    CalendarOutboxDispatchResponse,
+    CalendarOutboxOperationListResponse,
+    CalendarOutboxOperationResponse,
     CalendarSyncDueSyncItemResponse,
     CalendarSyncDueSyncResponse,
     CalendarSyncSourceCreateRequest,
@@ -44,11 +50,20 @@ from govoplan_calendar.backend.schemas import (
     CalendarSyncSourceSyncResponse,
     CalendarSyncSourceUpdateRequest,
 )
+from govoplan_calendar.backend.outbox import (
+    calendar_outbox_operation_response,
+    discard_calendar_outbox_operation,
+    dispatch_calendar_outbox,
+    list_calendar_outbox_operations,
+    reconcile_calendar_outbox_operation,
+    retry_calendar_outbox_operation,
+)
 from govoplan_calendar.backend.service import (
     CALENDAR_EVENTS_COLLECTION,
     CALENDAR_EVENT_RESOURCE,
     CALENDAR_MODULE_ID,
     CalendarError,
+    available_calendar_credentials,
     caldav_source_response,
     caldav_sync_response,
     calendar_response,
@@ -62,7 +77,6 @@ from govoplan_calendar.backend.service import (
     delete_event,
     discover_caldav_calendars,
     event_response,
-    get_caldav_source,
     get_event,
     import_ics_event,
     list_freebusy,
@@ -118,6 +132,25 @@ def _parse_payload_datetime(value) -> datetime | None:
         return None
 
 
+@router.get("/credentials", response_model=CalendarCredentialEnvelopeListResponse)
+def api_list_calendar_credentials(
+    source_id: str | None = None,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    return CalendarCredentialEnvelopeListResponse(
+        credentials=[
+            CalendarCredentialEnvelopeResponse.model_validate(item)
+            for item in available_calendar_credentials(
+                session,
+                tenant_id=principal.tenant_id,
+                source_id=source_id,
+            )
+        ]
+    )
+
+
 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
@@ -220,13 +253,25 @@ def _sync_source_response(source) -> CalendarSyncSourceResponse:
     return CalendarSyncSourceResponse.model_validate(caldav_source_response(source))
 
 
+def _outbox_operation_response(operation) -> CalendarOutboxOperationResponse:
+    return CalendarOutboxOperationResponse.model_validate(
+        calendar_outbox_operation_response(operation)
+    )
+
+
 @router.get("/calendars", response_model=CalendarCollectionListResponse)
 def api_list_calendars(
     principal: ApiPrincipal = Depends(get_api_principal),
     session: Session = Depends(get_session),
 ):
     _require_scope(principal, "calendar:calendar:read")
-    calendars = list_calendars(session, tenant_id=principal.tenant_id, user_id=principal.user.id)
+    calendars = list_calendars(
+        session,
+        tenant_id=principal.tenant_id,
+        user_id=principal.user.id,
+        group_ids=principal.group_ids,
+        can_admin=principal.has("calendar:calendar:admin"),
+    )
     session.commit()
     return CalendarCollectionListResponse(calendars=[_calendar_response(calendar) for calendar in calendars])
 
@@ -275,7 +320,14 @@ def api_delete_calendar(
 ):
     _require_scope(principal, "calendar:calendar:admin")
     try:
-        delete_calendar(session, tenant_id=principal.tenant_id, calendar_id=calendar_id, payload=payload)
+        delete_calendar(
+            session,
+            tenant_id=principal.tenant_id,
+            calendar_id=calendar_id,
+            payload=payload,
+            user_id=principal.user.id,
+            api_key_id=principal.api_key_id,
+        )
         session.commit()
         return Response(status_code=status.HTTP_204_NO_CONTENT)
     except CalendarError as exc:
@@ -321,7 +373,14 @@ def api_update_sync_source(
 ):
     _require_scope(principal, "calendar:calendar:admin")
     try:
-        source = update_sync_source(session, tenant_id=principal.tenant_id, source_id=source_id, payload=payload)
+        source = update_sync_source(
+            session,
+            tenant_id=principal.tenant_id,
+            source_id=source_id,
+            payload=payload,
+            user_id=principal.user.id,
+            api_key_id=principal.api_key_id,
+        )
         session.commit()
         session.refresh(source)
         return _sync_source_response(source)
@@ -338,12 +397,23 @@ def api_delete_sync_source(
 ):
     _require_scope(principal, "calendar:calendar:admin")
     try:
-        delete_sync_source(session, tenant_id=principal.tenant_id, source_id=source_id)
+        delete_sync_source(
+            session,
+            tenant_id=principal.tenant_id,
+            source_id=source_id,
+            user_id=principal.user.id,
+            api_key_id=principal.api_key_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
+        error_status = (
+            status.HTTP_404_NOT_FOUND
+            if "not found" in str(exc).lower()
+            else status.HTTP_409_CONFLICT
+        )
+        raise HTTPException(status_code=error_status, detail=str(exc)) from exc
 
 
 @router.post("/sync-sources/{source_id}/sync", response_model=CalendarSyncSourceSyncResponse)
@@ -451,7 +521,14 @@ def api_update_caldav_source(
 ):
     _require_scope(principal, "calendar:calendar:admin")
     try:
-        source = update_caldav_source(session, tenant_id=principal.tenant_id, source_id=source_id, payload=payload)
+        source = update_caldav_source(
+            session,
+            tenant_id=principal.tenant_id,
+            source_id=source_id,
+            payload=payload,
+            user_id=principal.user.id,
+            api_key_id=principal.api_key_id,
+        )
         session.commit()
         session.refresh(source)
         return _caldav_source_response(source)
@@ -468,12 +545,23 @@ def api_delete_caldav_source(
 ):
     _require_scope(principal, "calendar:calendar:admin")
     try:
-        delete_caldav_source(session, tenant_id=principal.tenant_id, source_id=source_id)
+        delete_caldav_source(
+            session,
+            tenant_id=principal.tenant_id,
+            source_id=source_id,
+            user_id=principal.user.id,
+            api_key_id=principal.api_key_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
+        error_status = (
+            status.HTTP_404_NOT_FOUND
+            if "not found" in str(exc).lower()
+            else status.HTTP_409_CONFLICT
+        )
+        raise HTTPException(status_code=error_status, detail=str(exc)) from exc
 
 
 @router.post("/caldav/sources/{source_id}/sync", response_model=CalendarCalDavSyncResponse)
@@ -530,6 +618,117 @@ def api_sync_due_caldav_sources(
     )
 
 
+@router.get("/caldav/outbox", response_model=CalendarOutboxOperationListResponse)
+def api_list_caldav_outbox(
+    operation_status: str | None = Query(default=None, alias="status"),
+    source_id: str | None = None,
+    limit: int = Query(default=100, ge=1, le=500),
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    operations = list_calendar_outbox_operations(
+        session,
+        tenant_id=principal.tenant_id,
+        status=operation_status,
+        source_id=source_id,
+        limit=limit,
+    )
+    return CalendarOutboxOperationListResponse(
+        operations=[_outbox_operation_response(operation) for operation in operations]
+    )
+
+
+@router.post("/caldav/outbox/dispatch", response_model=CalendarOutboxDispatchResponse)
+def api_dispatch_caldav_outbox(
+    limit: int = Query(default=50, ge=1, le=200),
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    return CalendarOutboxDispatchResponse.model_validate(
+        dispatch_calendar_outbox(
+            session,
+            tenant_id=principal.tenant_id,
+            limit=limit,
+        )
+    )
+
+
+@router.post(
+    "/caldav/outbox/{operation_id}/retry",
+    response_model=CalendarOutboxOperationResponse,
+)
+def api_retry_caldav_outbox_operation(
+    operation_id: str,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        operation = retry_calendar_outbox_operation(
+            session,
+            tenant_id=principal.tenant_id,
+            operation_id=operation_id,
+        )
+        session.commit()
+        session.refresh(operation)
+        return _outbox_operation_response(operation)
+    except ValueError as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail=str(exc)) from exc
+
+
+@router.post(
+    "/caldav/outbox/{operation_id}/reconcile",
+    response_model=CalendarOutboxOperationResponse,
+)
+def api_reconcile_caldav_outbox_operation(
+    operation_id: str,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        operation = reconcile_calendar_outbox_operation(
+            session,
+            tenant_id=principal.tenant_id,
+            operation_id=operation_id,
+        )
+        session.commit()
+        session.refresh(operation)
+        return _outbox_operation_response(operation)
+    except (ValueError, CalDAVError, CalendarError) as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.post(
+    "/caldav/outbox/{operation_id}/discard",
+    response_model=CalendarOutboxOperationResponse,
+)
+def api_discard_caldav_outbox_operation(
+    operation_id: str,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    """Abandon local desired state and allow the next sync to accept remote."""
+
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        operation = discard_calendar_outbox_operation(
+            session,
+            tenant_id=principal.tenant_id,
+            operation_id=operation_id,
+        )
+        session.commit()
+        session.refresh(operation)
+        return _outbox_operation_response(operation)
+    except ValueError as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail=str(exc)) from exc
+
+
 @router.get("/events", response_model=CalendarEventListResponse)
 def api_list_events(
     calendar_id: str | None = None,
@@ -600,7 +799,7 @@ def api_create_event(
     principal: ApiPrincipal = Depends(get_api_principal),
     session: Session = Depends(get_session),
 ):
-    _require_scope(principal, "calendar:event:write")
+    _require_scope(principal, CALENDAR_EVENT_WRITE_SCOPE)
     try:
         event = create_event(session, tenant_id=principal.tenant_id, user_id=principal.user.id, payload=payload)
         session.commit()
@@ -631,7 +830,7 @@ def api_update_event(
     principal: ApiPrincipal = Depends(get_api_principal),
     session: Session = Depends(get_session),
 ):
-    _require_scope(principal, "calendar:event:write")
+    _require_scope(principal, CALENDAR_EVENT_WRITE_SCOPE)
     try:
         event = update_event(session, tenant_id=principal.tenant_id, user_id=principal.user.id, event_id=event_id, payload=payload)
         session.commit()
@@ -648,7 +847,7 @@ def api_delete_event(
     principal: ApiPrincipal = Depends(get_api_principal),
     session: Session = Depends(get_session),
 ):
-    _require_any_scope(principal, "calendar:event:delete", "calendar:event:write")
+    _require_any_scope(principal, "calendar:event:delete", CALENDAR_EVENT_WRITE_SCOPE)
     try:
         delete_event(session, tenant_id=principal.tenant_id, event_id=event_id, user_id=principal.user.id)
         session.commit()
@@ -713,7 +912,7 @@ def api_freebusy(
     principal: ApiPrincipal = Depends(get_api_principal),
     session: Session = Depends(get_session),
 ):
-    _require_scope(principal, "calendar:availability:read")
+    _require_scope(principal, CALENDAR_AVAILABILITY_READ_SCOPE)
     try:
         busy = list_freebusy(
             session,

src/govoplan_calendar/backend/runtime.py

@@ -1,36 +1,10 @@
 from __future__ import annotations
 
-from typing import Any
+from govoplan_core.core.runtime import ModuleRuntimeState
 
-_runtime_registry: object | None = None
+_runtime = ModuleRuntimeState("Calendar")
-_runtime_settings: object | None = None
 
-
+configure_runtime = _runtime.configure_runtime
-def configure_runtime(*, registry: object | None = None, settings: object | None = None) -> None:
+get_registry = _runtime.get_registry
-    global _runtime_registry, _runtime_settings
+get_settings = _runtime.get_settings
-    if registry is not None:
+settings = _runtime.settings
-        _runtime_registry = registry
-    if settings is not None:
-        _runtime_settings = settings
-
-
-def get_registry() -> object | None:
-    return _runtime_registry
-
-
-def get_settings() -> object:
-    if _runtime_settings is not None:
-        return _runtime_settings
-    try:
-        from govoplan_core.settings import settings as legacy_settings
-    except ModuleNotFoundError as exc:
-        raise RuntimeError("GovOPlaN Calendar runtime settings are not configured") from exc
-    return legacy_settings
-
-
-class SettingsProxy:
-    def __getattr__(self, name: str) -> Any:
-        return getattr(get_settings(), name)
-
-
-settings = SettingsProxy()

src/govoplan_calendar/backend/schemas.py

@@ -11,6 +11,11 @@ from govoplan_core.api.v1.schemas import DeltaDeletedItem
 CalendarOwnerType = Literal["tenant", "user", "group", "resource"]
 CalendarVisibility = Literal["private", "tenant", "shared", "public"]
 CalendarDeleteEventAction = Literal["delete", "move"]
+CalendarBulkMoveExternalAction = Literal[
+    "detach_keep_remote",
+    "copy_to_remote",
+    "remote_move",
+]
 CalendarSyncAuthType = Literal["none", "basic", "bearer"]
 CalendarSyncDirection = Literal["inbound", "two_way"]
 CalendarSyncSourceKind = Literal["caldav", "ics", "webcal", "graph", "ews"]
@@ -50,6 +55,7 @@ class CalendarCollectionDeleteRequest(BaseModel):
     event_action: CalendarDeleteEventAction = "delete"
     target_calendar_id: str | None = None
     make_target_default: bool = False
+    external_action: CalendarBulkMoveExternalAction | None = None
 
 
 class CalendarCollectionResponse(BaseModel):
@@ -130,6 +136,7 @@ class CalendarSyncSourceResponse(BaseModel):
     auth_type: str
     username: str | None = None
     credential_ref: str | None = None
+    credential_envelope_id: str | None = None
     has_credential: bool = False
     sync_enabled: bool
     sync_interval_seconds: int
@@ -159,6 +166,26 @@ class CalendarCalDavSourceListResponse(BaseModel):
     sources: list[CalendarCalDavSourceResponse] = Field(default_factory=list)
 
 
+class CalendarCredentialEnvelopeResponse(BaseModel):
+    id: str
+    scope_type: str
+    scope_id: str | None = None
+    name: str
+    description: str | None = None
+    credential_kind: str
+    public_data: dict[str, Any] = Field(default_factory=dict)
+    secret_keys: list[str] = Field(default_factory=list)
+    secret_configured: bool = False
+    allowed_modules: list[str] = Field(default_factory=list)
+    inherit_to_lower_scopes: bool = False
+    is_active: bool = True
+    revision: str
+
+
+class CalendarCredentialEnvelopeListResponse(BaseModel):
+    credentials: list[CalendarCredentialEnvelopeResponse] = Field(default_factory=list)
+
+
 class CalendarCalDavDiscoveryRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 
@@ -238,6 +265,50 @@ class CalendarCalDavDueSyncResponse(BaseModel):
     results: list[CalendarCalDavDueSyncItemResponse] = Field(default_factory=list)
 
 
+class CalendarOutboxOperationResponse(BaseModel):
+    id: str
+    tenant_id: str
+    source_id: str
+    event_id: str | None = None
+    operation_kind: str
+    resource_href: str
+    payload_fingerprint: str | None = None
+    expected_etag: str | None = None
+    idempotency_key: str
+    status: str
+    attempt_count: int
+    max_attempts: int
+    available_at: datetime
+    last_attempt_at: datetime | None = None
+    lease_expires_at: datetime | None = None
+    completed_at: datetime | None = None
+    reconciled_at: datetime | None = None
+    remote_etag: str | None = None
+    last_error: str | None = None
+    created_at: datetime
+    updated_at: datetime
+    metadata: dict[str, Any] = Field(default_factory=dict)
+
+
+class CalendarOutboxOperationListResponse(BaseModel):
+    operations: list[CalendarOutboxOperationResponse] = Field(default_factory=list)
+
+
+class CalendarOutboxDispatchItemResponse(BaseModel):
+    id: str
+    status: str
+    attempt_count: int
+    last_error: str | None = None
+
+
+class CalendarOutboxDispatchResponse(BaseModel):
+    processed: int = 0
+    succeeded: int = 0
+    retrying: int = 0
+    failed: int = 0
+    operations: list[CalendarOutboxDispatchItemResponse] = Field(default_factory=list)
+
+
 class CalendarEventCreateRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 

tests/test_caldav.py

@@ -2,32 +2,47 @@ from __future__ import annotations
 
 import unittest
 from datetime import datetime, timezone
-from types import SimpleNamespace
 from unittest.mock import patch
 
-from sqlalchemy import create_engine
+from sqlalchemy import create_engine, inspect
 from sqlalchemy.orm import sessionmaker
 
 from govoplan_access.backend.db import models as access_models  # noqa: F401 - populate users/accounts tables
 from govoplan_calendar.backend.caldav import CalDAVClient, CalDAVError, CalDAVNotFound, CalDAVObject, CalDAVPreconditionFailed, CalDAVReportResult, CalDAVWriteResult, parse_multistatus
-from govoplan_calendar.backend.db.models import CalendarEvent, CalendarSyncCredential, CalendarSyncSource
+from govoplan_calendar.backend.db.models import CalendarEvent, CalendarOutboxOperation, CalendarSyncCredential
-from govoplan_calendar.backend.schemas import CalendarCalDavSourceCreateRequest, CalendarCollectionCreateRequest, CalendarEventCreateRequest, CalendarEventUpdateRequest
+from govoplan_calendar.backend.manifest import manifest
+from govoplan_calendar.backend.outbox import dispatch_calendar_outbox
+from govoplan_calendar.backend.schemas import (
+    CalendarCalDavDiscoveryRequest,
+    CalendarCalDavSourceCreateRequest,
+    CalendarCalDavSourceUpdateRequest,
+    CalendarCollectionCreateRequest,
+    CalendarEventCreateRequest,
+    CalendarEventUpdateRequest,
+)
 from govoplan_calendar.backend.service import (
     CALDAV_INTERNAL_CREDENTIAL_PREFIX,
     CalendarError,
     caldav_client_for_source,
+    caldav_source_response,
     create_calendar,
     create_caldav_source,
     create_event,
+    delete_caldav_source,
     delete_calendar,
     delete_event,
+    discover_caldav_calendars,
     list_caldav_sources,
     list_freebusy,
+    resolve_caldav_credential_ref,
+    resolve_trusted_deployment_caldav_credential_ref,
     sync_caldav_source,
     sync_due_caldav_sources,
+    update_caldav_source,
     update_event,
 )
 from govoplan_core.db.base import Base
+from govoplan_core.security.credential_envelopes import create_credential_envelope
 from govoplan_core.tenancy.scope import create_scope_tables
 from govoplan_tenancy.backend.db.models import Tenant
 
@@ -84,6 +99,14 @@ class FakeCalDAVClient:
         return CalDAVWriteResult(href=href, status=204)
 
 
+class FakeNotificationProvider:
+    def __init__(self) -> None:
+        self.requests: list[object] = []
+
+    def enqueue_notification(self, _session, request, **_kwargs) -> None:
+        self.requests.append(request)
+
+
 class CalDAVParsingTests(unittest.TestCase):
     def test_parse_multistatus_extracts_objects_sync_token_and_deletions(self) -> None:
         result = parse_multistatus(
@@ -216,10 +239,20 @@ END:VCALENDAR</C:calendar-data>
         self.assertEqual(calendars[0].collection_url, "https://cloud.example.test/remote.php/dav/calendars/ada/personal/")
 
     def test_discovery_reports_relative_url_as_caldav_error(self) -> None:
-        client = CalDAVClient(collection_url="/remote.php/dav")
+        with self.assertRaisesRegex(CalDAVError, "absolute HTTP"):
+            CalDAVClient(collection_url="/remote.php/dav")
 
-        with self.assertRaisesRegex(CalDAVError, "unknown url type"):
+    def test_object_url_rejects_off_origin_and_cross_collection_hrefs(self) -> None:
-            client.discover_calendars()
+        client = CalDAVClient(collection_url="https://dav.example.test/cal")
+
+        with self.assertRaisesRegex(CalDAVError, "collection origin"):
+            client.object_url("https://evil.example.test/steal.ics")
+        with self.assertRaisesRegex(CalDAVError, "collection path"):
+            client.object_url("https://dav.example.test/other/steal.ics")
+        self.assertEqual(
+            client.object_url("/cal/event.ics"),
+            "https://dav.example.test/cal/event.ics",
+        )
 
 
 class CalDAVSyncTests(unittest.TestCase):
@@ -228,12 +261,21 @@ class CalDAVSyncTests(unittest.TestCase):
         create_scope_tables(self.engine)
         Base.metadata.create_all(bind=self.engine)
         self.Session = sessionmaker(bind=self.engine)
+        self.sessions = []
 
     def tearDown(self) -> None:
+        for session in reversed(self.sessions):
+            session.close()
         Base.metadata.drop_all(bind=self.engine)
+        self.engine.dispose()
+
+    def session(self):
+        session = self.Session()
+        self.sessions.append(session)
+        return session
 
     def test_source_creation_encrypts_credential_and_resolves_client_secret(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
 
@@ -259,8 +301,261 @@ class CalDAVSyncTests(unittest.TestCase):
         self.assertEqual(client.username, "ada")
         self.assertEqual(client.password, "secret")
 
+    def test_source_can_resolve_reusable_core_credential(self) -> None:
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        credential = create_credential_envelope(
+            session,
+            tenant_id="tenant-1",
+            scope_type="tenant",
+            scope_id="tenant-1",
+            name="Shared DAV login",
+            credential_kind="username_password",
+            public_data={"username": "ada"},
+            secret_data={"password": "secret"},
+            allowed_modules=["calendar"],
+            inherit_to_lower_scopes=True,
+        )
+
+        source = create_caldav_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCalDavSourceCreateRequest(
+                calendar_id=calendar.id,
+                collection_url="https://dav.example.test/cal",
+                auth_type="basic",
+                credential_ref=f"credential-envelope:{credential.id}",
+            ),
+        )
+        session.commit()
+
+        client = caldav_client_for_source(session, source)
+        response = caldav_source_response(source)
+
+        self.assertEqual(client.username, "ada")
+        self.assertEqual(client.password, "secret")
+        self.assertEqual(response["credential_envelope_id"], credential.id)
+        self.assertEqual(session.query(CalendarSyncCredential).count(), 0)
+
+    def test_api_source_and_discovery_reject_caller_selected_credential_references(self) -> None:
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+
+        with self.assertRaisesRegex(CalendarError, "Caller-supplied credential references"):
+            create_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCalDavSourceCreateRequest(
+                    calendar_id=calendar.id,
+                    collection_url="https://attacker.example.test/cal",
+                    auth_type="bearer",
+                    credential_ref="env:MASTER_KEY_B64",
+                ),
+            )
+        with self.assertRaisesRegex(CalendarError, "Caller-supplied credential references"):
+            discover_caldav_calendars(
+                session,
+                tenant_id="tenant-1",
+                payload=CalendarCalDavDiscoveryRequest(
+                    url="https://attacker.example.test/cal",
+                    auth_type="bearer",
+                    credential_ref="vault:another-tenant",
+                ),
+            )
+        source = create_caldav_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCalDavSourceCreateRequest(
+                calendar_id=calendar.id,
+                collection_url="https://dav.example.test/cal",
+            ),
+        )
+        with self.assertRaisesRegex(CalendarError, "Caller-supplied credential references"):
+            update_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                source_id=source.id,
+                payload=CalendarCalDavSourceUpdateRequest(
+                    credential_ref="env:MASTER_KEY_B64",
+                ),
+            )
+
+    def test_provider_credentials_are_wrapped_in_tenant_and_source_owned_rows(self) -> None:
+        class Provider:
+            def __init__(self) -> None:
+                self.values: dict[str, str] = {}
+                self.deleted: list[str] = []
+
+            def store_secret(self, *, scope: str, name: str, value: str) -> str:
+                reference = f"vault:{scope}:{name}"
+                self.values[reference] = value
+                return reference
+
+            def read_secret(self, secret_ref: str) -> str | None:
+                return self.values.get(secret_ref)
+
+            def delete_secret(self, secret_ref: str) -> None:
+                self.deleted.append(secret_ref)
+                self.values.pop(secret_ref, None)
+
+        provider = Provider()
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=provider):
+            source = create_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCalDavSourceCreateRequest(
+                    calendar_id=calendar.id,
+                    collection_url="https://dav.example.test/cal",
+                    auth_type="basic",
+                    username="ada",
+                    password="secret",
+                ),
+            )
+            session.commit()
+            credential = session.query(CalendarSyncCredential).one()
+            provider_ref = str((credential.metadata_ or {})["provider_ref"])
+
+            self.assertTrue(source.credential_ref.startswith(CALDAV_INTERNAL_CREDENTIAL_PREFIX))
+            self.assertNotEqual(source.credential_ref, provider_ref)
+            self.assertEqual(caldav_client_for_source(session, source).password, "secret")
+            self.assertIsNone(caldav_source_response(source)["credential_ref"])
+            self.assertTrue(caldav_source_response(source)["has_credential"])
+            self.assertIsNone(
+                resolve_caldav_credential_ref(
+                    session,
+                    tenant_id="another-tenant",
+                    source_id=source.id,
+                    credential_ref=source.credential_ref,
+                )
+            )
+            self.assertIsNone(
+                resolve_caldav_credential_ref(
+                    session,
+                    tenant_id="tenant-1",
+                    source_id="another-source",
+                    credential_ref=source.credential_ref,
+                )
+            )
+
+            other_calendar = create_calendar(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCollectionCreateRequest(name="Other remote"),
+            )
+            other_source = create_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCalDavSourceCreateRequest(
+                    calendar_id=other_calendar.id,
+                    collection_url="https://dav.example.test/other-cal",
+                ),
+            )
+            other_source.auth_type = "basic"
+            other_source.username = "mallory"
+            other_source.credential_ref = source.credential_ref
+            with self.assertRaisesRegex(CalendarError, "not a server-owned credential"):
+                caldav_client_for_source(session, other_source)
+            delete_calendar(session, tenant_id="tenant-1", calendar_id=other_calendar.id)
+            self.assertEqual(provider.deleted, [])
+
+            with patch("govoplan_calendar.backend.service.audit_event") as audit:
+                delete_calendar(session, tenant_id="tenant-1", calendar_id=calendar.id)
+
+        self.assertEqual(provider.deleted, [provider_ref])
+        self.assertNotIn(provider_ref, provider.values)
+        self.assertIsNone(source.credential_ref)
+        self.assertIsNone(credential.secret_encrypted)
+        self.assertNotIn("provider_ref", credential.metadata_ or {})
+        audit.assert_called_once()
+        audit_call = audit.call_args.kwargs
+        self.assertEqual(audit_call["action"], "calendar.sync_credential_deleted")
+        self.assertEqual(audit_call["object_id"], credential.id)
+        self.assertEqual(audit_call["details"]["storage_backend"], "external_secret_provider")
+        self.assertEqual(audit_call["details"]["deletion_reason"], "calendar_deleted")
+        self.assertNotIn("credential_ref", audit_call["details"])
+        self.assertNotIn("provider_ref", audit_call["details"])
+        self.assertNotIn(provider_ref, repr(audit_call["details"]))
+
+    def test_legacy_unowned_refs_are_neither_read_nor_deleted(self) -> None:
+        class Provider:
+            def __init__(self) -> None:
+                self.read: list[str] = []
+                self.deleted: list[str] = []
+
+            def read_secret(self, secret_ref: str) -> str | None:
+                self.read.append(secret_ref)
+                return "other-tenant-secret"
+
+            def delete_secret(self, secret_ref: str) -> None:
+                self.deleted.append(secret_ref)
+
+        provider = Provider()
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        source = create_caldav_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCalDavSourceCreateRequest(
+                calendar_id=calendar.id,
+                collection_url="https://dav.example.test/cal",
+            ),
+        )
+        source.auth_type = "bearer"
+        source.credential_ref = "vault:another-tenant"
+        session.commit()
+
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=provider):
+            with self.assertRaisesRegex(CalendarError, "not a server-owned credential"):
+                caldav_client_for_source(session, source)
+            delete_calendar(session, tenant_id="tenant-1", calendar_id=calendar.id)
+
+        self.assertEqual(provider.read, [])
+        self.assertEqual(provider.deleted, [])
+
+    def test_trusted_deployment_env_resolution_is_explicit_and_separate(self) -> None:
+        with patch.dict("os.environ", {"CALDAV_DEPLOYMENT_TOKEN": "trusted-token"}):
+            self.assertEqual(
+                resolve_trusted_deployment_caldav_credential_ref("env:CALDAV_DEPLOYMENT_TOKEN"),
+                "trusted-token",
+            )
+        with self.assertRaisesRegex(CalendarError, "must use the env: prefix"):
+            resolve_trusted_deployment_caldav_credential_ref("vault:token")
+
     def test_delete_calendar_retires_caldav_source_and_credential(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
         source = create_caldav_source(
@@ -282,11 +577,319 @@ class CalDAVSyncTests(unittest.TestCase):
 
         credential = session.query(CalendarSyncCredential).one()
         self.assertIsNotNone(source.deleted_at)
+        self.assertIsNone(source.credential_ref)
         self.assertIsNotNone(credential.deleted_at)
+        self.assertIsNone(credential.secret_encrypted)
+        self.assertEqual(credential.metadata_, {"source_id": source.id})
         self.assertEqual(list_caldav_sources(session, tenant_id="tenant-1"), [])
 
+    def test_external_credential_deletion_fails_closed_when_provider_is_unavailable(self) -> None:
+        class Provider:
+            def __init__(self) -> None:
+                self.values: dict[str, str] = {}
+
+            def store_secret(self, *, scope: str, name: str, value: str) -> str:
+                reference = f"vault:{scope}:{name}"
+                self.values[reference] = value
+                return reference
+
+            def read_secret(self, secret_ref: str) -> str | None:
+                return self.values.get(secret_ref)
+
+            def delete_secret(self, secret_ref: str) -> None:
+                self.values.pop(secret_ref, None)
+
+        provider = Provider()
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=provider):
+            source = create_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCalDavSourceCreateRequest(
+                    calendar_id=calendar.id,
+                    collection_url="https://dav.example.test/provider-down",
+                    auth_type="bearer",
+                    bearer_token="do-not-log-this",
+                ),
+            )
+            session.commit()
+            credential = session.query(CalendarSyncCredential).one()
+            provider_ref = str((credential.metadata_ or {})["provider_ref"])
+
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=None), self.assertRaisesRegex(
+            CalendarError,
+            "secret provider is unavailable",
+        ):
+            delete_caldav_source(session, tenant_id="tenant-1", source_id=source.id)
+        session.rollback()
+
+        self.assertIsNone(source.deleted_at)
+        self.assertEqual(source.credential_ref, f"{CALDAV_INTERNAL_CREDENTIAL_PREFIX}{credential.id}")
+        self.assertIsNone(credential.deleted_at)
+        self.assertEqual((credential.metadata_ or {})["provider_ref"], provider_ref)
+        self.assertIn(provider_ref, provider.values)
+
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=provider), patch.object(
+            provider,
+            "delete_secret",
+            side_effect=RuntimeError(f"provider failed for {provider_ref}"),
+        ):
+            with self.assertRaises(CalendarError) as raised:
+                delete_caldav_source(session, tenant_id="tenant-1", source_id=source.id)
+        self.assertNotIn(provider_ref, str(raised.exception))
+        session.rollback()
+        self.assertIsNone(source.deleted_at)
+        self.assertIsNone(credential.deleted_at)
+
+    def test_disabling_auth_immediately_scrubs_and_audits_database_credential(self) -> None:
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        source = create_caldav_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCalDavSourceCreateRequest(
+                calendar_id=calendar.id,
+                collection_url="https://dav.example.test/disable-auth",
+                auth_type="basic",
+                username="ada",
+                password="do-not-log-this",
+            ),
+        )
+        session.commit()
+        credential = session.query(CalendarSyncCredential).one()
+        self.assertIsNotNone(credential.secret_encrypted)
+
+        with patch("govoplan_calendar.backend.service.audit_event") as audit:
+            update_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                source_id=source.id,
+                payload=CalendarCalDavSourceUpdateRequest(auth_type="none"),
+            )
+            session.commit()
+
+        self.assertIsNone(source.credential_ref)
+        self.assertIsNone(credential.secret_encrypted)
+        self.assertIsNotNone(credential.deleted_at)
+        audit.assert_called_once()
+        self.assertEqual(
+            audit.call_args.kwargs["details"]["deletion_reason"],
+            "authentication_disabled",
+        )
+        self.assertNotIn("do-not-log-this", repr(audit.call_args))
+
+    def test_external_credential_replacement_fails_closed_when_provider_is_unavailable(self) -> None:
+        class Provider:
+            def __init__(self) -> None:
+                self.values: dict[str, str] = {}
+
+            def store_secret(self, *, scope: str, name: str, value: str) -> str:
+                reference = f"vault:{scope}:{name}"
+                self.values[reference] = value
+                return reference
+
+            def read_secret(self, secret_ref: str) -> str | None:
+                return self.values.get(secret_ref)
+
+            def delete_secret(self, secret_ref: str) -> None:
+                self.values.pop(secret_ref, None)
+
+        provider = Provider()
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=provider):
+            source = create_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCalDavSourceCreateRequest(
+                    calendar_id=calendar.id,
+                    collection_url="https://dav.example.test/replacement-provider-down",
+                    auth_type="bearer",
+                    bearer_token="old-secret",
+                ),
+            )
+            session.commit()
+            credential = session.query(CalendarSyncCredential).one()
+            provider_ref = str((credential.metadata_ or {})["provider_ref"])
+
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=None), self.assertRaisesRegex(
+            CalendarError,
+            "cannot be replaced.*provider is unavailable",
+        ):
+            update_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                source_id=source.id,
+                payload=CalendarCalDavSourceUpdateRequest(bearer_token="new-secret"),
+            )
+        session.rollback()
+
+        self.assertEqual(source.credential_ref, f"{CALDAV_INTERNAL_CREDENTIAL_PREFIX}{credential.id}")
+        self.assertEqual((credential.metadata_ or {})["provider_ref"], provider_ref)
+        self.assertEqual(provider.values[provider_ref], "old-secret")
+
+    def test_external_credential_delete_is_retryable_after_database_rollback(self) -> None:
+        class Provider:
+            def __init__(self) -> None:
+                self.values: dict[str, str] = {}
+                self.deletes: list[str] = []
+
+            def store_secret(self, *, scope: str, name: str, value: str) -> str:
+                reference = f"vault:{scope}:{name}"
+                self.values[reference] = value
+                return reference
+
+            def read_secret(self, secret_ref: str) -> str | None:
+                return self.values.get(secret_ref)
+
+            def delete_secret(self, secret_ref: str) -> None:
+                self.deletes.append(secret_ref)
+                if secret_ref not in self.values:
+                    raise KeyError("already deleted")
+                self.values.pop(secret_ref, None)
+
+        provider = Provider()
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=provider):
+            source = create_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCalDavSourceCreateRequest(
+                    calendar_id=calendar.id,
+                    collection_url="https://dav.example.test/retry-delete",
+                    auth_type="basic",
+                    username="ada",
+                    password="do-not-log-this",
+                ),
+            )
+            session.commit()
+            credential = session.query(CalendarSyncCredential).one()
+            provider_ref = str((credential.metadata_ or {})["provider_ref"])
+
+            with patch("govoplan_calendar.backend.service.audit_event"):
+                delete_caldav_source(session, tenant_id="tenant-1", source_id=source.id)
+            self.assertNotIn(provider_ref, provider.values)
+            self.assertIsNotNone(credential.deleted_at)
+            self.assertIsNone(source.credential_ref)
+            session.rollback()
+
+            self.assertIsNone(source.deleted_at)
+            session.refresh(credential)
+            self.assertIsNone(credential.deleted_at)
+            self.assertEqual((credential.metadata_ or {})["provider_ref"], provider_ref)
+            self.assertIsNone(resolve_caldav_credential_ref(
+                session,
+                tenant_id="tenant-1",
+                source_id=source.id,
+                credential_ref=source.credential_ref,
+            ))
+
+            with patch("govoplan_calendar.backend.service.audit_event") as audit:
+                delete_caldav_source(session, tenant_id="tenant-1", source_id=source.id)
+                session.commit()
+
+        self.assertEqual(provider.deletes, [provider_ref, provider_ref])
+        self.assertIsNotNone(source.deleted_at)
+        self.assertIsNone(source.credential_ref)
+        self.assertIsNotNone(credential.deleted_at)
+        self.assertEqual(audit.call_count, 1)
+
+    def test_destructive_module_retirement_deletes_external_credentials_before_tables(self) -> None:
+        class Provider:
+            def __init__(self) -> None:
+                self.values: dict[str, str] = {}
+                self.deleted: list[str] = []
+
+            def store_secret(self, *, scope: str, name: str, value: str) -> str:
+                reference = f"vault:{scope}:{name}"
+                self.values[reference] = value
+                return reference
+
+            def read_secret(self, secret_ref: str) -> str | None:
+                return self.values.get(secret_ref)
+
+            def delete_secret(self, secret_ref: str) -> None:
+                self.deleted.append(secret_ref)
+                self.values.pop(secret_ref, None)
+
+        provider = Provider()
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCollectionCreateRequest(name="Remote"),
+        )
+        with patch("govoplan_calendar.backend.service.secret_provider", return_value=provider):
+            create_caldav_source(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarCalDavSourceCreateRequest(
+                    calendar_id=calendar.id,
+                    collection_url="https://dav.example.test/module-retirement",
+                    auth_type="bearer",
+                    bearer_token="do-not-log-this",
+                ),
+            )
+            session.commit()
+            credential = session.query(CalendarSyncCredential).one()
+            provider_ref = str((credential.metadata_ or {})["provider_ref"])
+            retirement_provider = manifest.migration_spec.retirement_provider
+            assert retirement_provider is not None
+            plan = retirement_provider(session, "calendar")
+            assert plan.destroy_data_executor is not None
+            with patch("govoplan_calendar.backend.service.audit_event") as audit:
+                plan.destroy_data_executor(session, "calendar")
+            # Retirement intentionally participates in the caller's database
+            # transaction. Commit before inspecting through a new Engine
+            # connection; otherwise SQLite rolls back the uncommitted DDL when
+            # the temporary inspector connection is returned to the pool.
+            session.commit()
+
+        self.assertEqual(provider.deleted, [provider_ref])
+        self.assertEqual(provider.values, {})
+        self.assertEqual(audit.call_count, 1)
+        self.assertEqual(
+            audit.call_args.kwargs["details"]["deletion_reason"],
+            "module_data_retired",
+        )
+        self.assertFalse(inspect(self.engine).has_table("calendar_sync_credentials"))
+        self.assertFalse(inspect(self.engine).has_table("calendar_sync_sources"))
+
     def test_create_source_retires_orphaned_source_for_deleted_calendar(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         old_calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Old"))
         old_source = create_caldav_source(
@@ -312,7 +915,7 @@ class CalDAVSyncTests(unittest.TestCase):
         self.assertEqual([source.id for source in list_caldav_sources(session, tenant_id="tenant-1")], [new_source.id])
 
     def test_create_source_reports_active_duplicate_as_calendar_error(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         first = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="First"))
         second = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Second"))
@@ -333,7 +936,7 @@ class CalDAVSyncTests(unittest.TestCase):
             )
 
     def test_due_sync_runs_due_sources_and_reschedules(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
         source = create_caldav_source(
@@ -359,15 +962,42 @@ class CalDAVSyncTests(unittest.TestCase):
         next_sync_at = source.next_sync_at if source.next_sync_at.tzinfo else source.next_sync_at.replace(tzinfo=timezone.utc)
         self.assertGreater(next_sync_at, datetime(2026, 7, 7, 8, 1, tzinfo=timezone.utc))
 
-    def test_create_and_update_event_puts_caldav_resource_with_etag(self) -> None:
+    def test_due_sync_emits_recovery_notification_after_previous_error(self) -> None:
-        session = self.Session()
+        session = self.session()
+        session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
+        calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
+        source = create_caldav_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarCalDavSourceCreateRequest(calendar_id=calendar.id, collection_url="https://dav.example.test/cal"),
+        )
+        source.last_status = "error"
+        source.next_sync_at = datetime(2026, 7, 7, 8, 0, tzinfo=timezone.utc)
+        session.commit()
+
+        provider = FakeNotificationProvider()
+        fake = FakeCalDAVClient(list_result=CalDAVReportResult(sync_token="token-1"))
+        with patch("govoplan_calendar.backend.service.notification_dispatch_provider", return_value=provider):
+            results = sync_due_caldav_sources(
+                session,
+                tenant_id="tenant-1",
+                now=datetime(2026, 7, 7, 8, 1, tzinfo=timezone.utc),
+                client_factory=lambda _source: fake,
+            )
+
+        self.assertEqual(results[0].status, "ok")
+        self.assertEqual(len(provider.requests), 1)
+        self.assertEqual(provider.requests[0].event_kind, "calendar.sync.ok")
+
+    def test_create_and_update_event_coalesce_to_committed_outbox_state(self) -> None:
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
         create_caldav_source(session, tenant_id="tenant-1", user_id=None, payload=CalendarCalDavSourceCreateRequest(calendar_id=calendar.id, collection_url="https://dav.example.test/cal"))
         session.commit()
 
-        fake = FakeCalDAVClient(put_etags=['"etag-1"', '"etag-2"'])
+        fake = FakeCalDAVClient(put_etags=['"etag-1"'])
-        with patch("govoplan_calendar.backend.service.caldav_client_for_source", return_value=fake):
         event = create_event(
             session,
             tenant_id="tenant-1",
@@ -381,18 +1011,22 @@ class CalDAVSyncTests(unittest.TestCase):
             ),
         )
         update_event(session, tenant_id="tenant-1", user_id=None, event_id=event.id, payload=CalendarEventUpdateRequest(summary="Updated"))
+        self.assertEqual(fake.puts, [])
         session.commit()
 
-        self.assertEqual(len(fake.puts), 2)
+        operations = session.query(CalendarOutboxOperation).all()
+        self.assertCountEqual([operation.status for operation in operations], ["superseded", "pending"])
+        dispatch_calendar_outbox(session, tenant_id="tenant-1", client_factory=lambda _session, _source: fake)
+
+        self.assertEqual(len(fake.puts), 1)
         self.assertTrue(fake.puts[0]["create"])
-        self.assertEqual(fake.puts[1]["etag"], '"etag-1"')
+        self.assertIn("SUMMARY:Updated", fake.puts[0]["ics"])
-        self.assertFalse(fake.puts[1]["create"])
         self.assertEqual(event.source_kind, "caldav")
-        self.assertEqual(event.etag, '"etag-2"')
+        self.assertEqual(event.etag, '"etag-1"')
         self.assertIn("SUMMARY:Updated", event.raw_ics or "")
 
     def test_update_event_reports_remote_etag_conflict(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
         create_caldav_source(session, tenant_id="tenant-1", user_id=None, payload=CalendarCalDavSourceCreateRequest(calendar_id=calendar.id, collection_url="https://dav.example.test/cal"))
@@ -400,13 +1034,25 @@ class CalDAVSyncTests(unittest.TestCase):
         session.add(event)
         session.commit()
 
-        fake = FakeCalDAVClient(fail_precondition=True)
+        fake = FakeCalDAVClient(
-        with patch("govoplan_calendar.backend.service.caldav_client_for_source", return_value=fake):
+            fail_precondition=True,
-            with self.assertRaisesRegex(CalendarError, "changed remotely"):
+            objects={event.source_href: recurring_resource()},
+        )
         update_event(session, tenant_id="tenant-1", user_id=None, event_id=event.id, payload=CalendarEventUpdateRequest(summary="Updated"))
+        session.commit()
+        result = dispatch_calendar_outbox(
+            session,
+            tenant_id="tenant-1",
+            client_factory=lambda _session, _source: fake,
+        )
+
+        self.assertEqual(result["failed"], 1)
+        operation = session.query(CalendarOutboxOperation).one()
+        self.assertEqual(operation.status, "conflict")
+        self.assertIn("changed remotely", operation.last_error or "")
 
     def test_delete_one_component_puts_remaining_resource_instead_of_deleting_object(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
         create_caldav_source(session, tenant_id="tenant-1", user_id=None, payload=CalendarCalDavSourceCreateRequest(calendar_id=calendar.id, collection_url="https://dav.example.test/cal"))
@@ -417,9 +1063,9 @@ class CalDAVSyncTests(unittest.TestCase):
         session.commit()
 
         fake = FakeCalDAVClient(put_etags=['"etag-2"'])
-        with patch("govoplan_calendar.backend.service.caldav_client_for_source", return_value=fake):
         delete_event(session, tenant_id="tenant-1", event_id=override.id)
         session.commit()
+        dispatch_calendar_outbox(session, tenant_id="tenant-1", client_factory=lambda _session, _source: fake)
 
         self.assertEqual(len(fake.puts), 1)
         self.assertEqual(fake.deletes, [])
@@ -429,7 +1075,7 @@ class CalDAVSyncTests(unittest.TestCase):
         self.assertIsNotNone(override.deleted_at)
 
     def test_freebusy_expands_recurring_events_and_skips_transparent_items(self) -> None:
-        session = self.Session()
+        session = self.session()
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Local"))
         create_event(
@@ -471,7 +1117,7 @@ class CalDAVSyncTests(unittest.TestCase):
         self.assertEqual(busy[0]["start_at"], datetime(2026, 7, 8, 9, 0, tzinfo=timezone.utc))
 
     def test_full_sync_imports_multi_vevent_resource_and_fetches_missing_calendar_data(self) -> None:
-        session = self.Session()
+        session = self.session()
         tenant = Tenant(id="tenant-1", slug="tenant-1", name="Tenant")
         session.add(tenant)
         calendar = create_calendar(
@@ -512,7 +1158,7 @@ class CalDAVSyncTests(unittest.TestCase):
         self.assertEqual(calendar.metadata_["source_kind"], "caldav")
 
     def test_sync_token_deletion_soft_deletes_remote_resource_events(self) -> None:
-        session = self.Session()
+        session = self.session()
         tenant = Tenant(id="tenant-1", slug="tenant-1", name="Tenant")
         session.add(tenant)
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
@@ -561,7 +1207,7 @@ class CalDAVSyncTests(unittest.TestCase):
         self.assertIsNotNone(event.deleted_at)
 
     def test_missing_resource_during_fetch_is_treated_as_remote_delete(self) -> None:
-        session = self.Session()
+        session = self.session()
         tenant = Tenant(id="tenant-1", slug="tenant-1", name="Tenant")
         session.add(tenant)
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))

tests/test_caldav_security.py

@@ -0,0 +1,142 @@
+from __future__ import annotations
+
+import contextlib
+import threading
+import unittest
+from collections.abc import Iterator
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from unittest.mock import patch
+
+from govoplan_calendar.backend.caldav import (
+    CalDAVClient,
+    CalDAVError,
+    absolute_dav_url,
+    urllib_transport,
+)
+
+
+@contextlib.contextmanager
+def running_http_server(handler: type[BaseHTTPRequestHandler]) -> Iterator[str]:
+    server = ThreadingHTTPServer(("127.0.0.1", 0), handler)
+    thread = threading.Thread(target=server.serve_forever, daemon=True)
+    thread.start()
+    try:
+        host, port = server.server_address
+        yield f"http://{host}:{port}"
+    finally:
+        server.shutdown()
+        server.server_close()
+        thread.join(timeout=2)
+
+
+class CalDAVUrlSecurityTests(unittest.TestCase):
+    def test_transport_revalidates_dns_at_connection_time(self) -> None:
+        public = [(2, 1, 6, "", ("93.184.216.34", 443))]
+        private = [(2, 1, 6, "", ("127.0.0.1", 443))]
+        with patch.dict(
+            "os.environ",
+            {"APP_ENV": "production", "GOVOPLAN_CONNECTOR_ALLOW_PRIVATE_NETWORKS": "false"},
+        ), patch(
+            "govoplan_core.security.outbound_http.socket.getaddrinfo",
+            side_effect=(public, private),
+        ), patch("govoplan_core.security.outbound_http.socket.socket") as socket_factory, self.assertRaisesRegex(
+            CalDAVError,
+            "non-public network",
+        ):
+            urllib_transport("GET", "https://dav.example.test/event.ics", {}, None, 2)
+        socket_factory.assert_not_called()
+
+    def test_discovery_href_must_remain_on_configured_origin(self) -> None:
+        base_url = "https://dav.example.test/calendars/ada/"
+
+        self.assertEqual(
+            absolute_dav_url(base_url, "/principals/users/ada/"),
+            "https://dav.example.test/principals/users/ada/",
+        )
+        with self.assertRaisesRegex(CalDAVError, "configured collection origin"):
+            absolute_dav_url(base_url, "https://evil.example.test/steal/")
+        with self.assertRaisesRegex(CalDAVError, "query or fragment"):
+            absolute_dav_url(base_url, "/principals/users/ada/?token=secret")
+
+    def test_object_href_rejects_userinfo_query_and_fragment(self) -> None:
+        client = CalDAVClient(collection_url="https://dav.example.test/calendars/ada")
+
+        with self.assertRaisesRegex(CalDAVError, "embedded credentials"):
+            client.object_url("https://user:secret@dav.example.test/calendars/ada/event.ics")
+        with self.assertRaisesRegex(CalDAVError, "query or fragment"):
+            client.object_url("/calendars/ada/event.ics?download=1")
+        with self.assertRaisesRegex(CalDAVError, "query or fragment"):
+            client.object_url("/calendars/ada/event.ics#fragment")
+        self.assertEqual(
+            client.object_url("/calendars/ada/event.ics"),
+            "https://dav.example.test/calendars/ada/event.ics",
+        )
+
+    def test_transport_refuses_redirect_before_forwarding_authorization(self) -> None:
+        forwarded_authorization: list[str | None] = []
+
+        class TargetHandler(BaseHTTPRequestHandler):
+            def do_GET(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
+                forwarded_authorization.append(self.headers.get("Authorization"))
+                self.send_response(200)
+                self.end_headers()
+
+            def log_message(self, _format: str, *_args: object) -> None:
+                return
+
+        with running_http_server(TargetHandler) as target_url:
+            class RedirectHandler(BaseHTTPRequestHandler):
+                def do_GET(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
+                    self.send_response(302)
+                    self.send_header("Location", f"{target_url}/stolen.ics")
+                    self.end_headers()
+
+                def log_message(self, _format: str, *_args: object) -> None:
+                    return
+
+            with running_http_server(RedirectHandler) as redirect_url:
+                status, _headers, _body = urllib_transport(
+                    "GET",
+                    f"{redirect_url}/event.ics",
+                    {"Authorization": "Bearer top-secret"},
+                    None,
+                    2,
+                )
+
+        self.assertEqual(status, 302)
+        self.assertEqual(forwarded_authorization, [])
+
+    def test_transport_preserves_same_origin_redirects(self) -> None:
+        forwarded_authorization: list[str | None] = []
+
+        class RedirectHandler(BaseHTTPRequestHandler):
+            def do_GET(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
+                if self.path == "/event.ics":
+                    self.send_response(302)
+                    self.send_header("Location", "/redirected.ics")
+                    self.end_headers()
+                    return
+                forwarded_authorization.append(self.headers.get("Authorization"))
+                self.send_response(200)
+                self.end_headers()
+                self.wfile.write(b"calendar")
+
+            def log_message(self, _format: str, *_args: object) -> None:
+                return
+
+        with running_http_server(RedirectHandler) as source_url:
+            status, _headers, body = urllib_transport(
+                "GET",
+                f"{source_url}/event.ics",
+                {"Authorization": "Bearer expected"},
+                None,
+                2,
+            )
+
+        self.assertEqual(status, 200)
+        self.assertEqual(body, b"calendar")
+        self.assertEqual(forwarded_authorization, ["Bearer expected"])
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_capabilities.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+import unittest
+from datetime import datetime, timezone
+
+from govoplan_calendar.backend.capabilities import SqlCalendarSchedulingProvider
+from govoplan_core.core.calendar import CalendarCapabilityError, CalendarEventRequest
+
+
+class CalendarSchedulingCapabilityTests(unittest.TestCase):
+    def test_event_request_validation_is_exposed_as_capability_error(self) -> None:
+        provider = SqlCalendarSchedulingProvider()
+
+        with self.assertRaises(CalendarCapabilityError):
+            provider.create_event(
+                object(),
+                tenant_id="tenant-1",
+                user_id="user-1",
+                request=CalendarEventRequest(
+                    summary="x" * 501,
+                    start_at=datetime(2026, 7, 20, 9, tzinfo=timezone.utc),
+                ),
+            )
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_http_security.py

@@ -0,0 +1,90 @@
+from __future__ import annotations
+
+import contextlib
+import threading
+import unittest
+from collections.abc import Iterator
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+
+from govoplan_calendar.backend.service import CalendarError, http_request
+
+
+@contextlib.contextmanager
+def running_http_server(handler: type[BaseHTTPRequestHandler]) -> Iterator[str]:
+    server = ThreadingHTTPServer(("127.0.0.1", 0), handler)
+    thread = threading.Thread(target=server.serve_forever, daemon=True)
+    thread.start()
+    try:
+        host, port = server.server_address
+        yield f"http://{host}:{port}"
+    finally:
+        server.shutdown()
+        server.server_close()
+        thread.join(timeout=2)
+
+
+class CalendarHttpSecurityTests(unittest.TestCase):
+    def test_cross_origin_redirect_does_not_forward_authorization(self) -> None:
+        forwarded_authorization: list[str | None] = []
+
+        class TargetHandler(BaseHTTPRequestHandler):
+            def do_GET(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
+                forwarded_authorization.append(self.headers.get("Authorization"))
+                self.send_response(200)
+                self.end_headers()
+
+            def log_message(self, _format: str, *_args: object) -> None:
+                return
+
+        with running_http_server(TargetHandler) as target_url:
+            class RedirectHandler(BaseHTTPRequestHandler):
+                def do_GET(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
+                    self.send_response(302)
+                    self.send_header("Location", f"{target_url}/stolen")
+                    self.end_headers()
+
+                def log_message(self, _format: str, *_args: object) -> None:
+                    return
+
+            with running_http_server(RedirectHandler) as source_url:
+                with self.assertRaisesRegex(CalendarError, "HTTP 302"):
+                    http_request(
+                        f"{source_url}/feed",
+                        headers={"Authorization": "Bearer top-secret"},
+                        timeout=2,
+                    )
+
+        self.assertEqual(forwarded_authorization, [])
+
+    def test_same_origin_redirect_remains_supported(self) -> None:
+        forwarded_authorization: list[str | None] = []
+
+        class RedirectHandler(BaseHTTPRequestHandler):
+            def do_GET(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
+                if self.path == "/feed":
+                    self.send_response(302)
+                    self.send_header("Location", "/calendar.ics")
+                    self.end_headers()
+                    return
+                forwarded_authorization.append(self.headers.get("Authorization"))
+                self.send_response(200)
+                self.end_headers()
+                self.wfile.write(b"calendar")
+
+            def log_message(self, _format: str, *_args: object) -> None:
+                return
+
+        with running_http_server(RedirectHandler) as source_url:
+            status, _headers, body = http_request(
+                f"{source_url}/feed",
+                headers={"Authorization": "Bearer expected"},
+                timeout=2,
+            )
+
+        self.assertEqual(status, 200)
+        self.assertEqual(body, "calendar")
+        self.assertEqual(forwarded_authorization, ["Bearer expected"])
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_service.py

@@ -6,7 +6,7 @@ from types import SimpleNamespace
 from unittest.mock import patch
 
 from govoplan_calendar.backend.schemas import CalendarCollectionDeleteRequest, CalendarEventResponse
-from govoplan_calendar.backend.service import delete_calendar, event_response
+from govoplan_calendar.backend.service import calendar_is_visible_to_principal, delete_calendar, event_response
 
 
 class FakeSession:
@@ -65,6 +65,67 @@ class CalendarServiceResponseTests(unittest.TestCase):
         self.assertEqual(response.start_at.tzinfo, timezone.utc)
 
 
+class CalendarVisibilityTests(unittest.TestCase):
+    @staticmethod
+    def calendar(**overrides):
+        values = {
+            "visibility": "private",
+            "owner_type": "user",
+            "owner_id": "owner-1",
+            "created_by_user_id": "creator-1",
+        }
+        values.update(overrides)
+        return SimpleNamespace(**values)
+
+    def test_tenant_shared_and_public_calendars_are_visible_to_readers(self) -> None:
+        for visibility in ("tenant", "shared", "public"):
+            with self.subTest(visibility=visibility):
+                self.assertTrue(
+                    calendar_is_visible_to_principal(
+                        self.calendar(visibility=visibility),
+                        user_id="reader-1",
+                    )
+                )
+
+    def test_private_calendar_is_visible_to_user_owner_creator_or_group_member(self) -> None:
+        self.assertTrue(
+            calendar_is_visible_to_principal(
+                self.calendar(),
+                user_id="owner-1",
+            )
+        )
+        self.assertTrue(
+            calendar_is_visible_to_principal(
+                self.calendar(),
+                user_id="creator-1",
+            )
+        )
+        self.assertTrue(
+            calendar_is_visible_to_principal(
+                self.calendar(owner_type="group", owner_id="group-1"),
+                user_id="member-1",
+                group_ids=("group-1",),
+            )
+        )
+
+    def test_private_calendar_is_hidden_from_other_readers_but_visible_to_admin(self) -> None:
+        calendar = self.calendar()
+        self.assertFalse(
+            calendar_is_visible_to_principal(
+                calendar,
+                user_id="other-1",
+                group_ids=("group-2",),
+            )
+        )
+        self.assertTrue(
+            calendar_is_visible_to_principal(
+                calendar,
+                user_id="other-1",
+                can_admin=True,
+            )
+        )
+
+
 class CalendarServiceDeleteTests(unittest.TestCase):
     def test_delete_default_calendar_soft_deletes_calendar_and_events(self) -> None:
         session = FakeSession()

tests/test_sync_sources.py

@@ -11,7 +11,7 @@ from sqlalchemy.orm import sessionmaker
 from govoplan_access.backend.db import models as access_models  # noqa: F401 - populate users/accounts tables
 from govoplan_calendar.backend.db.models import CalendarEvent
 from govoplan_calendar.backend.schemas import CalendarCollectionCreateRequest, CalendarEventCreateRequest, CalendarSyncSourceCreateRequest
-from govoplan_calendar.backend.service import CalendarError, create_calendar, create_event, create_sync_source, sync_source
+from govoplan_calendar.backend.service import CalendarError, create_calendar, create_event, create_sync_source, soft_delete_unseen_source_events, sync_source
 from govoplan_core.db.base import Base
 from govoplan_core.tenancy.scope import create_scope_tables
 from govoplan_tenancy.backend.db.models import Tenant
@@ -23,12 +23,17 @@ class CalendarSyncSourceTests(unittest.TestCase):
         create_scope_tables(self.engine)
         Base.metadata.create_all(bind=self.engine)
         self.Session = sessionmaker(bind=self.engine)
+        self.sessions = []
 
     def tearDown(self) -> None:
+        for session in reversed(self.sessions):
+            session.close()
         Base.metadata.drop_all(bind=self.engine)
+        self.engine.dispose()
 
     def session_with_calendar(self):
         session = self.Session()
+        self.sessions.append(session)
         session.add(Tenant(id="tenant-1", slug="tenant-1", name="Tenant"))
         calendar = create_calendar(session, tenant_id="tenant-1", user_id=None, payload=CalendarCollectionCreateRequest(name="Remote"))
         session.flush()
@@ -78,6 +83,55 @@ END:VCALENDAR
                 ),
             )
 
+    def test_ics_not_modified_sync_clears_error_and_reschedules(self) -> None:
+        session, calendar = self.session_with_calendar()
+        source = create_sync_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarSyncSourceCreateRequest(
+                source_kind="ics",
+                calendar_id=calendar.id,
+                collection_url="https://calendar.example.test/feed.ics",
+            ),
+        )
+        source.ctag = '"feed-1"'
+        source.last_status = "error"
+        source.last_error = "previous failure"
+
+        with patch("govoplan_calendar.backend.service.http_request", return_value=(304, {}, "")):
+            refreshed, stats = sync_source(session, tenant_id="tenant-1", user_id=None, source_id=source.id)
+
+        self.assertEqual(refreshed.last_status, "ok")
+        self.assertIsNone(refreshed.last_error)
+        self.assertIsNotNone(refreshed.last_synced_at)
+        self.assertIsNotNone(refreshed.next_sync_at)
+        self.assertEqual(stats.created, 0)
+        self.assertEqual(stats.updated, 0)
+        self.assertEqual(stats.deleted, 0)
+
+    def test_ics_sync_failure_records_error_and_reschedules(self) -> None:
+        session, calendar = self.session_with_calendar()
+        source = create_sync_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarSyncSourceCreateRequest(
+                source_kind="ics",
+                calendar_id=calendar.id,
+                collection_url="https://calendar.example.test/feed.ics",
+            ),
+        )
+
+        with patch("govoplan_calendar.backend.service.http_request", side_effect=RuntimeError("network down")):
+            with self.assertRaisesRegex(RuntimeError, "network down"):
+                sync_source(session, tenant_id="tenant-1", user_id=None, source_id=source.id)
+
+        self.assertEqual(source.last_status, "error")
+        self.assertIn("network down", source.last_error or "")
+        self.assertIsNotNone(source.last_attempt_at)
+        self.assertIsNotNone(source.next_sync_at)
+
     def test_graph_sync_imports_delta_events(self) -> None:
         session, calendar = self.session_with_calendar()
         source = create_sync_source(
@@ -117,6 +171,74 @@ END:VCALENDAR
         self.assertEqual(event.summary, "Graph item")
         self.assertIn("Bearer graph-token", request.call_args.kwargs["headers"]["Authorization"])
 
+    def test_graph_sync_rejects_cross_origin_continuation_url(self) -> None:
+        session, calendar = self.session_with_calendar()
+        source = create_sync_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarSyncSourceCreateRequest(
+                source_kind="graph",
+                calendar_id=calendar.id,
+                collection_url="me/calendar",
+                auth_type="bearer",
+                bearer_token="graph-token",
+            ),
+        )
+        payload = {
+            "value": [],
+            "@odata.nextLink": "https://attacker.example.test/collect?token=secret",
+        }
+
+        with patch(
+            "govoplan_calendar.backend.service.http_request",
+            return_value=(200, {}, json.dumps(payload)),
+        ) as request:
+            with self.assertRaisesRegex(CalendarError, "configured source origin"):
+                sync_source(
+                    session,
+                    tenant_id="tenant-1",
+                    user_id=None,
+                    source_id=source.id,
+                )
+
+        self.assertEqual(request.call_count, 1)
+        self.assertEqual(source.last_status, "error")
+
+    def test_graph_sync_rejects_cross_origin_delta_url(self) -> None:
+        session, calendar = self.session_with_calendar()
+        source = create_sync_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarSyncSourceCreateRequest(
+                source_kind="graph",
+                calendar_id=calendar.id,
+                collection_url="me/calendar",
+                auth_type="bearer",
+                bearer_token="graph-token",
+            ),
+        )
+        payload = {
+            "value": [],
+            "@odata.deltaLink": "https://attacker.example.test/collect?token=secret",
+        }
+
+        with patch(
+            "govoplan_calendar.backend.service.http_request",
+            return_value=(200, {}, json.dumps(payload)),
+        ) as request:
+            with self.assertRaisesRegex(CalendarError, "configured source origin"):
+                sync_source(
+                    session,
+                    tenant_id="tenant-1",
+                    user_id=None,
+                    source_id=source.id,
+                )
+
+        self.assertEqual(request.call_count, 1)
+        self.assertEqual(source.last_status, "error")
+
     def test_ews_sync_imports_calendar_view_items(self) -> None:
         session, calendar = self.session_with_calendar()
         source = create_sync_source(
@@ -168,6 +290,59 @@ END:VCALENDAR
         self.assertEqual(event.summary, "EWS item")
         self.assertTrue(request.call_args.kwargs["body"].startswith("<?xml"))
 
+    def test_full_sync_cleanup_soft_deletes_unseen_events_in_batches(self) -> None:
+        session, calendar = self.session_with_calendar()
+        source = create_sync_source(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarSyncSourceCreateRequest(
+                source_kind="ics",
+                calendar_id=calendar.id,
+                collection_url="https://calendar.example.test/events.ics",
+            ),
+        )
+        for index in range(3):
+            session.add(
+                CalendarEvent(
+                    tenant_id="tenant-1",
+                    calendar_id=calendar.id,
+                    uid=f"event-{index}@example.test",
+                    recurrence_id=None,
+                    summary=f"Event {index}",
+                    status="CONFIRMED",
+                    transparency="OPAQUE",
+                    classification="PUBLIC",
+                    start_at=datetime(2026, 7, 8, 9 + index, tzinfo=timezone.utc),
+                    all_day=False,
+                    attendees=[],
+                    categories=[],
+                    rdate=[],
+                    exdate=[],
+                    reminders=[],
+                    attachments=[],
+                    related_to=[],
+                    source_kind="ics",
+                    source_href=f"ics-event-{index}",
+                    icalendar={},
+                )
+            )
+        session.flush()
+
+        deleted = soft_delete_unseen_source_events(
+            session,
+            source=source,
+            seen_hrefs={"ics-event-1"},
+            batch_size=1,
+        )
+
+        active_hrefs = {
+            event.source_href
+            for event in session.query(CalendarEvent).filter(CalendarEvent.deleted_at.is_(None)).all()
+        }
+        self.assertEqual(deleted, 2)
+        self.assertEqual(active_hrefs, {"ics-event-1"})
+
 
 if __name__ == "__main__":
     unittest.main()

webui/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@govoplan/calendar-webui",
-  "version": "0.1.6",
+  "version": "0.1.8",
   "private": true,
   "type": "module",
   "main": "src/index.ts",
@@ -13,8 +13,11 @@
     },
     "./styles/calendar.css": "./src/styles/calendar.css"
   },
+  "scripts": {
+    "test:calendar-picker": "rm -rf .calendar-picker-test-build && mkdir -p .calendar-picker-test-build && printf '{\"type\":\"commonjs\"}\\n' > .calendar-picker-test-build/package.json && tsc -p tsconfig.calendar-picker-tests.json && node .calendar-picker-test-build/tests/calendar-picker.test.js && node tests/calendar-picker-structure.test.mjs"
+  },
   "peerDependencies": {
-    "@govoplan/core-webui": "^0.1.6",
+    "@govoplan/core-webui": "^0.1.9",
     "lucide-react": "^1.23.0",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",

webui/src/api/calendar.ts

@@ -78,7 +78,7 @@ export type CalendarSyncSource = {
   display_name?: string | null;
   auth_type: CalendarCalDavAuthType;
   username?: string | null;
-  credential_ref?: string | null;
+  credential_envelope_id?: string | null;
   has_credential: boolean;
   sync_enabled: boolean;
   sync_interval_seconds: number;
@@ -143,6 +143,26 @@ export type CalendarCalDavSourceCreatePayload = CalendarSyncSourceCreatePayload;
 export type CalendarCalDavSourceUpdatePayload = Partial<CalendarCalDavSourceCreatePayload>;
 export type CalendarSyncSourceUpdatePayload = Partial<CalendarSyncSourceCreatePayload>;
 
+export type CalendarCredentialEnvelope = {
+  id: string;
+  scope_type: string;
+  scope_id?: string | null;
+  name: string;
+  description?: string | null;
+  credential_kind: string;
+  public_data: Record<string, unknown>;
+  secret_keys: string[];
+  secret_configured: boolean;
+  allowed_modules: string[];
+  inherit_to_lower_scopes: boolean;
+  is_active: boolean;
+  revision: string;
+};
+
+export type CalendarCredentialEnvelopeListResponse = {
+  credentials: CalendarCredentialEnvelope[];
+};
+
 export type CalendarSyncSourceSyncPayload = {
   password?: string | null;
   bearer_token?: string | null;
@@ -182,10 +202,12 @@ export type CalendarCollectionCreatePayload = {
 
 export type CalendarCollectionUpdatePayload = Partial<CalendarCollectionCreatePayload>;
 export type CalendarDeleteEventAction = "delete" | "move";
+export type CalendarBulkMoveExternalAction = "detach_keep_remote" | "copy_to_remote" | "remote_move";
 export type CalendarCollectionDeletePayload = {
   event_action?: CalendarDeleteEventAction;
   target_calendar_id?: string | null;
   make_target_default?: boolean;
+  external_action?: CalendarBulkMoveExternalAction | null;
 };
 
 export type CalendarEventCreatePayload = {
@@ -253,6 +275,13 @@ export function listCalDavSources(settings: ApiSettings, params: { calendar_id?:
   return apiFetch<CalendarCalDavSourceListResponse>(settings, `/api/v1/calendar/caldav/sources${suffix}`);
 }
 
+export function listCalendarCredentials(settings: ApiSettings, sourceId?: string | null): Promise<CalendarCredentialEnvelopeListResponse> {
+  const search = new URLSearchParams();
+  if (sourceId) search.set("source_id", sourceId);
+  const suffix = search.toString() ? `?${search.toString()}` : "";
+  return apiFetch<CalendarCredentialEnvelopeListResponse>(settings, `/api/v1/calendar/credentials${suffix}`);
+}
+
 export function discoverCalDavCalendars(settings: ApiSettings, payload: CalendarCalDavDiscoveryPayload): Promise<CalendarCalDavDiscoveryResponse> {
   return apiFetch<CalendarCalDavDiscoveryResponse>(settings, "/api/v1/calendar/caldav/discover", { method: "POST", body: JSON.stringify(payload) });
 }

webui/src/features/calendar/CalendarPage.tsx

@@ -11,13 +11,16 @@ import {
 "react";
 import { CalendarDays, ChevronLeft, ChevronRight, Pencil, Plus, RefreshCw, Trash2 } from "lucide-react";
 import {
+  AdminIconButton,
   Button,
   ColorPickerField,
   DateField,
   Dialog,
   DismissibleAlert,
   LoadingFrame,
+  PasswordField,
   SegmentedControl,
+  TableActionGroup,
   TimeField,
   ToggleSwitch,
   hasScope,
@@ -35,6 +38,7 @@ import {
   discoverCalDavCalendars,
   listCalendarEvents,
   listCalendarEventsDelta,
+  listCalendarCredentials,
   listCalendars,
   listSyncSources,
   syncSyncSource,
@@ -46,8 +50,10 @@ import {
   type CalendarCalDavDiscoveryCandidate,
   type CalendarCalDavDiscoveryPayload,
   type CalendarCalDavSyncDirection,
+  type CalendarBulkMoveExternalAction,
   type CalendarCollection,
   type CalendarCollectionDeletePayload,
+  type CalendarCredentialEnvelope,
   type CalendarDeleteEventAction,
   type CalendarEvent,
   type CalendarEventCreatePayload,
@@ -83,7 +89,7 @@ type CalendarCalDavFormPayload = {
   display_name: string;
   auth_type: CalendarCalDavAuthType;
   username: string;
-  credential_ref: string;
+  credential_envelope_id: string;
   password: string;
   bearer_token: string;
   sync_enabled: boolean;
@@ -234,8 +240,10 @@ export default function CalendarPage({ settings, auth }: {settings: ApiSettings;
     setLoading(true);
     setError("");
     try {
-      const response = await listCalendars(settings);
+      const [response, sourceResponse] = await Promise.all([
-      const sourceResponse = await listSyncSources(settings);
+        listCalendars(settings),
+        listSyncSources(settings)
+      ]);
       setCalendars(response.calendars);
       setSyncSources(sourceResponse.sources);
       const ids = response.calendars.map((calendar) => calendar.id);
@@ -681,31 +689,24 @@ export default function CalendarPage({ settings, auth }: {settings: ApiSettings;
                   <button type="button" className="calendar-list-name" onClick={() => setEventCalendarId(calendar.id)}>
                     {calendar.name}
                   </button>
-                  <div className="calendar-list-actions">
+                  <TableActionGroup
-                    {source && canSyncCalendars &&
+                    className="calendar-list-actions"
-                    <Button
+                    actions={[
-                      type="button"
+                      source && canSyncCalendars && {
-                      className={syncing ? "calendar-row-icon-button is-syncing" : "calendar-row-icon-button"}
+                        id: "sync",
-                      title={syncing ? i18nMessage("i18n:govoplan-calendar.syncing_value.ca80b487", { value0: calendar.name }) : i18nMessage("i18n:govoplan-calendar.sync_value.72e4ba66", { value0: calendar.name })}
+                        label: syncing ? i18nMessage("i18n:govoplan-calendar.syncing_value.ca80b487", { value0: calendar.name }) : i18nMessage("i18n:govoplan-calendar.sync_value.72e4ba66", { value0: calendar.name }),
-                      aria-label={syncing ? i18nMessage("i18n:govoplan-calendar.syncing_value.ca80b487", { value0: calendar.name }) : i18nMessage("i18n:govoplan-calendar.sync_value.72e4ba66", { value0: calendar.name })}
+                        icon: <RefreshCw size={15} className={syncing ? "calendar-sync-spin" : undefined} />,
-                      onClick={() => void handleSyncSource(source)}
+                        onClick: () => void handleSyncSource(source),
-                      disabled={saving || syncing}>
+                        disabled: saving || syncing
-
+                      },
-                        <RefreshCw size={15} className={syncing ? "calendar-sync-spin" : undefined} />
+                      (canManageCalendars || canDeleteCalendars) && {
-                      </Button>
+                        id: "edit",
+                        label: i18nMessage("i18n:govoplan-calendar.edit_value.fad75899", { value0: calendar.name }),
+                        icon: <Pencil size={15} />,
+                        onClick: () => openCalendarEditor(calendar)
                       }
-                    {(canManageCalendars || canDeleteCalendars) &&
+                    ]}
-                    <Button
+                  />
-                      type="button"
-                      className="calendar-row-icon-button"
-                      title={i18nMessage("i18n:govoplan-calendar.edit_value.fad75899", { value0: calendar.name })}
-                      aria-label={i18nMessage("i18n:govoplan-calendar.edit_value.fad75899", { value0: calendar.name })}
-                      onClick={() => openCalendarEditor(calendar)}>
-
-                        <Pencil size={15} />
-                      </Button>
-                    }
-                  </div>
                 </div>);
 
             })}
@@ -761,13 +762,19 @@ export default function CalendarPage({ settings, auth }: {settings: ApiSettings;
 
             <div className="calendar-toolbar-center">
               <div className="calendar-icon-group" aria-label="i18n:govoplan-calendar.calendar_navigation.7ba43cd2">
-                <Button type="button" className="calendar-icon-button" title="i18n:govoplan-calendar.previous.50f94286" aria-label="i18n:govoplan-calendar.previous.50f94286" onClick={() => moveFocus(-1)} disabled={mode === "continuous"}>
+                <AdminIconButton
-                  <ChevronLeft size={18} />
+                  label="i18n:govoplan-calendar.previous.50f94286"
-                </Button>
+                  icon={<ChevronLeft size={18} />}
+                  onClick={() => moveFocus(-1)}
+                  disabled={mode === "continuous"}
+                />
                 <Button type="button" onClick={handleToday}>i18n:govoplan-calendar.today.24345a14</Button>
-                <Button type="button" className="calendar-icon-button" title="i18n:govoplan-calendar.next.bc981983" aria-label="i18n:govoplan-calendar.next.bc981983" onClick={() => moveFocus(1)} disabled={mode === "continuous"}>
+                <AdminIconButton
-                  <ChevronRight size={18} />
+                  label="i18n:govoplan-calendar.next.bc981983"
-                </Button>
+                  icon={<ChevronRight size={18} />}
+                  onClick={() => moveFocus(1)}
+                  disabled={mode === "continuous"}
+                />
                 <div className="calendar-range-label">
                   <CalendarDays size={18} aria-hidden="true" />
                   <strong>{heading}</strong>
@@ -776,9 +783,11 @@ export default function CalendarPage({ settings, auth }: {settings: ApiSettings;
             </div>
 
             <div className="calendar-toolbar-right">
-              <Button type="button" className="calendar-icon-button" title="i18n:govoplan-calendar.refresh.56e3badc" aria-label="i18n:govoplan-calendar.refresh.56e3badc" onClick={() => void loadEvents()}>
+              <AdminIconButton
-                <RefreshCw size={18} />
+                label="i18n:govoplan-calendar.refresh.56e3badc"
-              </Button>
+                icon={<RefreshCw size={18} />}
+                onClick={() => void loadEvents()}
+              />
               {canWrite &&
               <Button type="button" variant="primary" onClick={() => setEventDialog({ kind: "create" })} disabled={!targetCalendarId}>
                   <Plus size={17} /> i18n:govoplan-calendar.new.6403f2b7
@@ -877,6 +886,7 @@ export default function CalendarPage({ settings, auth }: {settings: ApiSettings;
       <CalendarCollectionDialog
         key={calendarDialog.kind === "edit" ? calendarDialog.calendar.id : "new-calendar"}
         state={calendarDialog}
+        settings={settings}
         source={calendarDialog.kind === "edit" ? syncSourceByCalendarId.get(calendarDialog.calendar.id) ?? null : null}
         saving={saving}
         syncingSourceId={syncingSourceId}
@@ -895,6 +905,7 @@ export default function CalendarPage({ settings, auth }: {settings: ApiSettings;
       <CalendarCollectionDeleteDialog
         state={calendarDeleteDialog}
         calendars={calendars}
+        syncSources={syncSources}
         saving={saving}
         onCancel={() => setCalendarDeleteDialog(null)}
         onDelete={handleCalendarDelete} />
@@ -1302,6 +1313,7 @@ function CalendarEventChip({
 
 function CalendarCollectionDialog({
   state,
+  settings,
   source,
   saving,
   syncingSourceId,
@@ -1328,7 +1340,7 @@ function CalendarCollectionDialog({
 
 
 
-}: {state: CalendarCollectionDialogState;source: CalendarSyncSource | null;saving: boolean;syncingSourceId: string;canWrite: boolean;canDelete: boolean;canManageSources: boolean;canSyncSources: boolean;onCancel: () => void;onSave: (payload: CalendarCollectionFormPayload) => Promise<boolean>;onRequestDelete: (calendar: CalendarCollection, eventCount: number | null, loadingEventCount: boolean) => void;onSync: (source: CalendarSyncSource, payload?: {password?: string | null;bearer_token?: string | null;force_full?: boolean;}) => Promise<void>;onDiscover: (payload: CalendarCalDavDiscoveryPayload) => Promise<{calendars: CalendarCalDavDiscoveryCandidate[];}>;}) {
+}: {state: CalendarCollectionDialogState;settings: ApiSettings;source: CalendarSyncSource | null;saving: boolean;syncingSourceId: string;canWrite: boolean;canDelete: boolean;canManageSources: boolean;canSyncSources: boolean;onCancel: () => void;onSave: (payload: CalendarCollectionFormPayload) => Promise<boolean>;onRequestDelete: (calendar: CalendarCollection, eventCount: number | null, loadingEventCount: boolean) => void;onSync: (source: CalendarSyncSource, payload?: {password?: string | null;bearer_token?: string | null;force_full?: boolean;}) => Promise<void>;onDiscover: (payload: CalendarCalDavDiscoveryPayload) => Promise<{calendars: CalendarCalDavDiscoveryCandidate[];}>;}) {
   const calendar = state.kind === "edit" ? state.calendar : null;
   const isEdit = Boolean(calendar);
   const [sourceMode, setSourceMode] = useState<CalendarSourceMode>(source ? source.source_kind : "local");
@@ -1339,7 +1351,9 @@ function CalendarCollectionDialog({
   const [displayName, setDisplayName] = useState(source?.display_name ?? "");
   const [authType, setAuthType] = useState<CalendarCalDavAuthType>(source?.auth_type ?? "basic");
   const [username, setUsername] = useState(source?.username ?? "");
-  const [credentialRef, setCredentialRef] = useState(source?.credential_ref ?? "");
+  const [credentialEnvelopeId, setCredentialEnvelopeId] = useState(source?.credential_envelope_id ?? "");
+  const [availableCredentials, setAvailableCredentials] = useState<CalendarCredentialEnvelope[]>([]);
+  const [credentialsError, setCredentialsError] = useState("");
   const [password, setPassword] = useState("");
   const [bearerToken, setBearerToken] = useState("");
   const [syncEnabled, setSyncEnabled] = useState(source?.sync_enabled ?? true);
@@ -1357,8 +1371,8 @@ function CalendarCollectionDialog({
   const effectiveCollectionUrl = (collectionUrl || davUrl).trim();
   const effectiveAuthType = sourceMode === "graph" ? "bearer" : authType;
   const needsSourceSecret = sourceMode !== "local" && (
-  effectiveAuthType === "basic" && !source?.has_credential && !credentialRef.trim() && !password.trim() ||
+  effectiveAuthType === "basic" && !source?.has_credential && !credentialEnvelopeId && !password.trim() ||
-  effectiveAuthType === "bearer" && !source?.has_credential && !credentialRef.trim() && !bearerToken.trim());
+  effectiveAuthType === "bearer" && !source?.has_credential && !credentialEnvelopeId && !bearerToken.trim());
 
   const sourceDetailsInvalid = sourceMode !== "local" && (
   !isExistingSyncSource && !canEditSource ||
@@ -1381,7 +1395,7 @@ function CalendarCollectionDialog({
     displayName,
     authType,
     username,
-    credentialRef,
+    credentialEnvelopeId,
     password,
     bearerToken,
     syncEnabled,
@@ -1398,6 +1412,28 @@ function CalendarCollectionDialog({
     onDiscard: onCancel
   });
 
+  useEffect(() => {
+    if (sourceMode === "local" || !canManageSources) {
+      setAvailableCredentials([]);
+      setCredentialsError("");
+      return;
+    }
+    let active = true;
+    listCalendarCredentials(settings, source?.id)
+      .then((response) => {
+        if (active) setAvailableCredentials(response.credentials);
+      })
+      .catch((err) => {
+        if (active) {
+          setAvailableCredentials([]);
+          setCredentialsError(errorText(err));
+        }
+      });
+    return () => {
+      active = false;
+    };
+  }, [canManageSources, settings.accessToken, settings.apiBaseUrl, settings.apiKey, source?.id, sourceMode]);
+
   function currentPayload(): CalendarCollectionFormPayload {
     return {
       sourceMode,
@@ -1409,7 +1445,7 @@ function CalendarCollectionDialog({
         display_name: displayName,
         auth_type: effectiveAuthType,
         username,
-        credential_ref: credentialRef,
+        credential_envelope_id: credentialEnvelopeId,
         password,
         bearer_token: bearerToken,
         sync_enabled: syncEnabled,
@@ -1490,11 +1526,11 @@ function CalendarCollectionDialog({
         url,
         source_id: source?.id ?? null,
         auth_type: authType,
-        username: authType === "basic" ? username.trim() || null : null,
+        username: authType === "basic" ? username.trim() || null : null
-        credential_ref: credentialRef.trim() || null
       };
-      if (authType === "basic" && password.trim()) payload.password = password;
+      if (credentialEnvelopeId) payload.credential_ref = credentialEnvelopeRef(credentialEnvelopeId);
-      if (authType === "bearer" && bearerToken.trim()) payload.bearer_token = bearerToken;
+      if (!credentialEnvelopeId && authType === "basic" && password.trim()) payload.password = password;
+      if (!credentialEnvelopeId && authType === "bearer" && bearerToken.trim()) payload.bearer_token = bearerToken;
       const response = await onDiscover(payload);
       setDiscoveredCalendars(response.calendars);
       if (response.calendars.length > 0) {
@@ -1602,22 +1638,49 @@ function CalendarCollectionDialog({
                   <option value="bearer">i18n:govoplan-calendar.bearer_token.ffa64bcf</option>
                 </select>
               </label>
+              {effectiveAuthType !== "none" &&
+              <label>
+                <span>Reusable credential</span>
+                <select
+                  value={credentialEnvelopeId}
+                  disabled={saving || !canEditSource}
+                  onChange={(event) => {
+                    const credentialId = event.target.value;
+                    setCredentialEnvelopeId(credentialId);
+                    setPassword("");
+                    setBearerToken("");
+                    const credential = availableCredentials.find((item) => item.id === credentialId);
+                    const credentialUsername = credential?.public_data?.username;
+                    if (credentialUsername) setUsername(String(credentialUsername));
+                  }}>
+                  <option value="">{source?.has_credential && !source.credential_envelope_id ? "Keep source-specific credential" : "Enter credentials below"}</option>
+                  {availableCredentials.map((credential) =>
+                    <option key={credential.id} value={credential.id}>
+                      {credential.name}{credential.public_data?.username ? ` (${String(credential.public_data.username)})` : ""}
+                    </option>
+                  )}
+                </select>
+              </label>
+              }
+              {credentialsError && <p className="calendar-form-error calendar-dialog-wide">{credentialsError}</p>}
               {effectiveAuthType === "basic" &&
             <>
                   <label>
                     <span>i18n:govoplan-calendar.username.84c29015</span>
-                    <input value={username} onChange={(item) => setUsername(item.target.value)} required={sourceMode !== "local" && effectiveAuthType === "basic"} maxLength={255} disabled={saving || !canEditSource} />
+                    <input value={username} onChange={(item) => setUsername(item.target.value)} required={sourceMode !== "local" && effectiveAuthType === "basic"} maxLength={255} disabled={saving || !canEditSource || Boolean(credentialEnvelopeId)} />
                   </label>
+                  {!credentialEnvelopeId &&
                   <label>
-                    <span>{source?.has_credential || credentialRef.trim() ? "i18n:govoplan-calendar.replace_password.3f912c9c" : "i18n:govoplan-calendar.password.8be3c943"}</span>
+                    <span>{source?.has_credential ? "i18n:govoplan-calendar.replace_password.3f912c9c" : "i18n:govoplan-calendar.password.8be3c943"}</span>
-                    <input type="password" value={password} onChange={(item) => setPassword(item.target.value)} disabled={saving || !canEditSource} autoComplete="new-password" />
+                    <PasswordField value={password} onValueChange={setPassword} disabled={saving || !canEditSource} autoComplete="new-password" />
                   </label>
+                  }
                 </>
             }
-              {effectiveAuthType === "bearer" &&
+              {effectiveAuthType === "bearer" && !credentialEnvelopeId &&
             <label>
-                  <span>{source?.has_credential || credentialRef.trim() ? "i18n:govoplan-calendar.replace_token.bbeee6a9" : "i18n:govoplan-calendar.bearer_token.ffa64bcf"}</span>
+                  <span>{source?.has_credential ? "i18n:govoplan-calendar.replace_token.bbeee6a9" : "i18n:govoplan-calendar.bearer_token.ffa64bcf"}</span>
-                  <input type="password" value={bearerToken} onChange={(item) => setBearerToken(item.target.value)} disabled={saving || !canEditSource} autoComplete="new-password" />
+                  <PasswordField value={bearerToken} onValueChange={setBearerToken} disabled={saving || !canEditSource} autoComplete="new-password" />
                 </label>
             }
               <div className={sourceMode === "caldav" ? "calendar-discovery-actions" : "calendar-discovery-actions is-readonly"}>
@@ -1649,10 +1712,6 @@ function CalendarCollectionDialog({
                   <span>i18n:govoplan-calendar.display_name.c7874aaa</span>
                   <input value={displayName} onChange={(item) => setDisplayName(item.target.value)} maxLength={255} disabled={saving || !canEditMutableSourceSettings} />
                 </label>
-                <label>
-                  <span>i18n:govoplan-calendar.credential_reference.a7e92de5</span>
-                  <input value={credentialRef} onChange={(item) => setCredentialRef(item.target.value)} placeholder="env:CALDAV_PASSWORD" maxLength={255} disabled={saving || !canEditSource} />
-                </label>
               </div>
               <div className="calendar-sync-settings">
                 <ToggleSwitch label="i18n:govoplan-calendar.automatic_sync.084644b2" checked={syncEnabled} disabled={saving || !canEditMutableSourceSettings} onChange={setSyncEnabled} />
@@ -1682,7 +1741,7 @@ function CalendarCollectionDialog({
                   <div><dt>i18n:govoplan-calendar.last_attempt.82aee111</dt><dd>{source.last_attempt_at ? dateTimeLabel(new Date(source.last_attempt_at)) : "i18n:govoplan-calendar.never.80c3052d"}</dd></div>
                   <div><dt>i18n:govoplan-calendar.last_sync.ef0ef267</dt><dd>{source.last_synced_at ? dateTimeLabel(new Date(source.last_synced_at)) : "i18n:govoplan-calendar.never.80c3052d"}</dd></div>
                   <div><dt>i18n:govoplan-calendar.next_sync.88c7af72</dt><dd>{source.next_sync_at && source.sync_enabled ? dateTimeLabel(new Date(source.next_sync_at)) : "i18n:govoplan-calendar.not_scheduled.9c367369"}</dd></div>
-                  <div><dt>i18n:govoplan-calendar.credential.8bede3ea</dt><dd>{source.has_credential || source.credential_ref ? "i18n:govoplan-calendar.configured.668c5fff" : "i18n:govoplan-calendar.not_configured.811931bb"}</dd></div>
+                  <div><dt>i18n:govoplan-calendar.credential.8bede3ea</dt><dd>{source.has_credential ? "i18n:govoplan-calendar.configured.668c5fff" : "i18n:govoplan-calendar.not_configured.811931bb"}</dd></div>
                 </dl>
                 {source.last_error && <p className="calendar-form-error">{source.last_error}</p>}
                 <div className="calendar-sync-actions">
@@ -1700,7 +1759,7 @@ function CalendarCollectionDialog({
                 </div>
               </div>
           }
-            {sourceMode !== "local" && effectiveAuthType !== "none" && !source?.has_credential && !credentialRef.trim() && <p className="calendar-form-note">i18n:govoplan-calendar.enter_a_secret_now_or_use_an_environment_referen.6db0e6ce <code>env:CALENDAR_SYNC_SECRET</code>.</p>}
+            {needsSourceSecret && <p className="calendar-form-note">i18n:govoplan-calendar.enter_a_password_or_token_for_this_source.74c09a54</p>}
           </section>
         }
       </form>
@@ -1711,6 +1770,7 @@ function CalendarCollectionDialog({
 function CalendarCollectionDeleteDialog({
   state,
   calendars,
+  syncSources,
   saving,
   onCancel,
   onDelete
@@ -1720,9 +1780,13 @@ function CalendarCollectionDeleteDialog({
 
 
 
-}: {state: CalendarDeleteDialogState;calendars: CalendarCollection[];saving: boolean;onCancel: () => void;onDelete: (calendar: CalendarCollection, payload: CalendarCollectionDeletePayload) => Promise<void>;}) {
+}: {state: CalendarDeleteDialogState;calendars: CalendarCollection[];syncSources: CalendarSyncSource[];saving: boolean;onCancel: () => void;onDelete: (calendar: CalendarCollection, payload: CalendarCollectionDeletePayload) => Promise<void>;}) {
   const { calendar, eventCount, loadingEventCount } = state;
-  const moveTargets = calendars.filter((item) => item.id !== calendar.id);
+  const syncSourceByCalendarId = new Map(syncSources.map((source) => [source.calendar_id, source]));
+  const source = syncSourceByCalendarId.get(calendar.id) ?? null;
+  const moveTargets = calendars.filter((item) =>
+  item.id !== calendar.id && calendarMoveTargetIsSupported(source, syncSourceByCalendarId.get(item.id) ?? null)
+  );
   const firstMoveTargetId = moveTargets[0]?.id || "";
   const hasEvents = (eventCount ?? 0) > 0;
   const canMoveEvents = hasEvents && moveTargets.length > 0;
@@ -1732,12 +1796,15 @@ function CalendarCollectionDeleteDialog({
   const effectiveEventAction: CalendarDeleteEventAction = canMoveEvents ? eventAction : "delete";
   const confirmDisabled = saving || loadingEventCount || canMoveEvents && effectiveEventAction === "move" && !targetCalendarId;
   const actionLabel = calendarDeleteActionLabel(calendar);
+  const targetSource = syncSourceByCalendarId.get(targetCalendarId) ?? null;
+  const externalAction = calendarBulkMoveExternalAction(source, targetSource);
 
   function confirm() {
     void onDelete(calendar, {
       event_action: effectiveEventAction,
       target_calendar_id: effectiveEventAction === "move" ? targetCalendarId : null,
-      make_target_default: effectiveEventAction === "move" && calendar.is_default && makeTargetDefault
+      make_target_default: effectiveEventAction === "move" && calendar.is_default && makeTargetDefault,
+      external_action: effectiveEventAction === "move" ? externalAction : null
     });
   }
 
@@ -1787,7 +1854,7 @@ function CalendarCollectionDeleteDialog({
               checked={eventAction === "move"}
               onChange={() => setEventAction("move")} />
 
-              <span>i18n:govoplan-calendar.move_events_to_another_calendar.830c7b09</span>
+              <span>{calendarBulkMoveOptionLabel(externalAction)}</span>
             </label>
             {eventAction === "move" &&
           <>
@@ -1800,15 +1867,18 @@ function CalendarCollectionDeleteDialog({
                   </select>
                 </label>
                 {calendar.is_default &&
-            <label className="calendar-checkbox-row">
+                  <ToggleSwitch label="i18n:govoplan-calendar.make_target_calendar_the_default.10a3977b" checked={makeTargetDefault} onChange={setMakeTargetDefault} />
-                    <input type="checkbox" checked={makeTargetDefault} onChange={(item) => setMakeTargetDefault(item.target.checked)} />
-                    <span>i18n:govoplan-calendar.make_target_calendar_the_default.10a3977b</span>
-                  </label>
             }
+                <p className="calendar-form-note">{calendarBulkMoveConsequence(externalAction)}</p>
               </>
           }
           </fieldset>
         }
+        {!loadingEventCount && hasEvents && moveTargets.length === 0 &&
+        <p className="calendar-form-note">{source ?
+          "i18n:govoplan-calendar.no_local_target_calendar_is_available_add_a_local_.fad3cb65" :
+          "i18n:govoplan-calendar.no_compatible_target_calendar_is_available_add_a_l.1cf6e47b"}</p>
+        }
       </div>
     </Dialog>);
 
@@ -2402,15 +2472,19 @@ function syncSourceCreatePayload(sourceMode: CalendarSourceMode, payload: Calend
     display_name: payload.display_name.trim() || null,
     auth_type: sourceKind === "graph" ? "bearer" : payload.auth_type,
     username: sourceKind !== "graph" && payload.auth_type === "basic" ? payload.username.trim() || null : null,
-    credential_ref: payload.credential_ref.trim() || null,
     sync_enabled: payload.sync_enabled,
     sync_interval_seconds: Math.max(60, payload.sync_interval_seconds),
     sync_direction: sourceKind === "caldav" ? payload.sync_direction : "inbound",
     conflict_policy: payload.conflict_policy,
     metadata: {}
   };
-  if (result.auth_type === "basic" && payload.password.trim()) result.password = payload.password;
+  if (payload.credential_envelope_id) {
-  if (result.auth_type === "bearer" && payload.bearer_token.trim()) result.bearer_token = payload.bearer_token;
+    result.credential_ref = credentialEnvelopeRef(payload.credential_envelope_id);
+  } else if (result.auth_type === "basic" && payload.password.trim()) {
+    result.password = payload.password;
+  } else if (result.auth_type === "bearer" && payload.bearer_token.trim()) {
+    result.bearer_token = payload.bearer_token;
+  }
   return result;
 }
 
@@ -2418,14 +2492,22 @@ function syncSourceConnectionUpdatePayload(payload: CalendarCalDavFormPayload):
   const result: CalendarSyncSourceUpdatePayload = {
     collection_url: payload.collection_url.trim(),
     auth_type: payload.auth_type,
-    username: payload.auth_type === "basic" ? payload.username.trim() || null : null,
+    username: payload.auth_type === "basic" ? payload.username.trim() || null : null
-    credential_ref: payload.credential_ref.trim() || null
   };
-  if (payload.auth_type === "basic" && payload.password.trim()) result.password = payload.password;
+  if (payload.credential_envelope_id) {
-  if (payload.auth_type === "bearer" && payload.bearer_token.trim()) result.bearer_token = payload.bearer_token;
+    result.credential_ref = credentialEnvelopeRef(payload.credential_envelope_id);
+  } else if (payload.auth_type === "basic" && payload.password.trim()) {
+    result.password = payload.password;
+  } else if (payload.auth_type === "bearer" && payload.bearer_token.trim()) {
+    result.bearer_token = payload.bearer_token;
+  }
   return result;
 }
 
+function credentialEnvelopeRef(credentialId: string): string {
+  return `credential-envelope:${credentialId}`;
+}
+
 function syncSourceKindForMode(sourceMode: CalendarSourceMode, collectionUrl: string): CalendarSyncSourceKind {
   if (sourceMode === "ics" && collectionUrl.trim().toLowerCase().startsWith("webcal://")) return "webcal";
   return sourceMode === "local" ? "caldav" : sourceMode;
@@ -2471,6 +2553,39 @@ function calendarEventDeleteOptionLabel(calendar: CalendarCollection): string {
   return calendarIsExternal(calendar) ? "i18n:govoplan-calendar.remove_local_events_with_this_calendar.fb8831e1" : "i18n:govoplan-calendar.delete_events_with_this_calendar.cc0e1287";
 }
 
+function calendarMoveTargetIsSupported(
+source: CalendarSyncSource | null,
+targetSource: CalendarSyncSource | null)
+: boolean {
+  if (source) return targetSource === null;
+  return targetSource === null || calendarSyncSourceAcceptsCopies(targetSource);
+}
+
+function calendarSyncSourceAcceptsCopies(source: CalendarSyncSource): boolean {
+  return source.source_kind === "caldav" && source.sync_enabled && source.sync_direction === "two_way";
+}
+
+function calendarBulkMoveExternalAction(
+source: CalendarSyncSource | null,
+targetSource: CalendarSyncSource | null)
+: CalendarBulkMoveExternalAction | undefined {
+  if (source && !targetSource) return "detach_keep_remote";
+  if (!source && targetSource && calendarSyncSourceAcceptsCopies(targetSource)) return "copy_to_remote";
+  return undefined;
+}
+
+function calendarBulkMoveOptionLabel(action: CalendarBulkMoveExternalAction | undefined): string {
+  if (action === "detach_keep_remote") return "i18n:govoplan-calendar.detach_local_events_and_keep_remote_events.c58ad4e7";
+  if (action === "copy_to_remote") return "i18n:govoplan-calendar.move_and_copy_events_to_the_external_calendar.23c3a004";
+  return "i18n:govoplan-calendar.move_events_to_another_calendar.830c7b09";
+}
+
+function calendarBulkMoveConsequence(action: CalendarBulkMoveExternalAction | undefined): string {
+  if (action === "detach_keep_remote") return "i18n:govoplan-calendar.govoplan_moves_the_local_event_copies_to_the_targe.4863e46b";
+  if (action === "copy_to_remote") return "i18n:govoplan-calendar.govoplan_moves_the_events_locally_and_queues_durab.da075b16";
+  return "i18n:govoplan-calendar.events_remain_in_govoplan_no_external_calendar_is_.62cb5937";
+}
+
 function calendarDeleteWarning(
 calendar: CalendarCollection,
 eventCount: number,

webui/src/features/calendar/CalendarPicker.tsx

@@ -0,0 +1,114 @@
+import { useEffect, useId, useMemo, useState } from "react";
+import {
+  FormField,
+  hasScope,
+  type CalendarPickerProps
+} from "@govoplan/core-webui";
+import { listCalendars, type CalendarCollection } from "../../api/calendar";
+import {
+  CALENDAR_PICKER_READ_SCOPE,
+  calendarPickerOptions,
+  calendarPickerTenantId
+} from "./calendarPickerLogic";
+
+const LABEL = "i18n:govoplan-calendar.calendar.adab5090";
+const SELECT_CALENDAR = "i18n:govoplan-calendar.select_calendar.f38b5ba2";
+const LOADING_CALENDARS = "i18n:govoplan-calendar.loading_calendars.afbb957b";
+const CALENDARS_UNAVAILABLE = "i18n:govoplan-calendar.calendars_are_unavailable.f074c862";
+const NO_CALENDARS_AVAILABLE = "i18n:govoplan-calendar.no_calendars_are_available.711d2cf3";
+const SELECTED_CALENDAR_UNAVAILABLE = "i18n:govoplan-calendar.the_selected_calendar_is_no_longer_available.39f0f1f5";
+
+export default function CalendarPicker({
+  settings,
+  auth,
+  value,
+  onChange,
+  id,
+  name,
+  label = LABEL,
+  emptyLabel = SELECT_CALENDAR,
+  disabled = false,
+  required = false,
+  className
+}: CalendarPickerProps) {
+  const generatedId = useId();
+  const selectId = id ?? `calendar-picker-${generatedId.replace(/:/g, "")}`;
+  const statusId = `${selectId}-status`;
+  const [calendars, setCalendars] = useState<CalendarCollection[]>([]);
+  const [loading, setLoading] = useState(false);
+  const [failed, setFailed] = useState(false);
+  const canRead = hasScope(auth, CALENDAR_PICKER_READ_SCOPE);
+  const tenantId = calendarPickerTenantId(auth);
+
+  useEffect(() => {
+    let cancelled = false;
+    if (!canRead) {
+      setCalendars([]);
+      setLoading(false);
+      setFailed(true);
+      return () => {
+        cancelled = true;
+      };
+    }
+
+    setLoading(true);
+    setFailed(false);
+    listCalendars(settings)
+      .then((response) => {
+        if (!cancelled) setCalendars(response.calendars);
+      })
+      .catch(() => {
+        if (!cancelled) {
+          setCalendars([]);
+          setFailed(true);
+        }
+      })
+      .finally(() => {
+        if (!cancelled) setLoading(false);
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [canRead, settings.accessToken, settings.apiBaseUrl, settings.apiKey, tenantId]);
+
+  const options = useMemo(() => calendarPickerOptions(calendars), [calendars]);
+  const selectedUnavailable = Boolean(value) && !loading && !options.some((calendar) => calendar.id === value);
+  const status = failed
+    ? CALENDARS_UNAVAILABLE
+    : !loading && options.length === 0
+      ? NO_CALENDARS_AVAILABLE
+      : selectedUnavailable
+        ? SELECTED_CALENDAR_UNAVAILABLE
+        : "";
+  const placeholder = loading
+    ? LOADING_CALENDARS
+    : failed
+      ? CALENDARS_UNAVAILABLE
+      : options.length === 0
+        ? NO_CALENDARS_AVAILABLE
+        : emptyLabel;
+
+  return (
+    <div className={["calendar-picker", className].filter(Boolean).join(" ")}>
+      <FormField label={label}>
+        <select
+          id={selectId}
+          name={name}
+          value={value}
+          required={required}
+          disabled={disabled || loading || failed || options.length === 0}
+          aria-busy={loading || undefined}
+          aria-describedby={status ? statusId : undefined}
+          onChange={(event) => onChange(event.target.value)}
+        >
+          <option value="">{placeholder}</option>
+          {selectedUnavailable ? <option value={value} disabled>{SELECTED_CALENDAR_UNAVAILABLE}</option> : null}
+          {options.map((calendar) => (
+            <option key={calendar.id} value={calendar.id}>{calendar.name}</option>
+          ))}
+        </select>
+      </FormField>
+      {status ? <div id={statusId} className="muted small-note" role={failed ? "alert" : "status"}>{status}</div> : null}
+    </div>
+  );
+}

webui/src/features/calendar/calendarPickerLogic.ts

@@ -0,0 +1,24 @@
+type CalendarPickerAuth = {
+  tenant: { id: string };
+  active_tenant?: { id: string };
+};
+
+export type CalendarPickerOption = {
+  id: string;
+  name: string;
+  is_default: boolean;
+};
+
+export const CALENDAR_PICKER_READ_SCOPE = "calendar:calendar:read";
+
+export function calendarPickerOptions<TCalendar extends CalendarPickerOption>(calendars: TCalendar[]): TCalendar[] {
+  return [...calendars].sort((left, right) => {
+    if (left.is_default !== right.is_default) return left.is_default ? -1 : 1;
+    const nameDelta = left.name.localeCompare(right.name, undefined, { sensitivity: "base" });
+    return nameDelta !== 0 ? nameDelta : left.id.localeCompare(right.id);
+  });
+}
+
+export function calendarPickerTenantId(auth: CalendarPickerAuth): string {
+  return (auth.active_tenant ?? auth.tenant).id;
+}

webui/src/i18n/generatedTranslations.ts

@@ -24,6 +24,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.calendar_source_type.92cdb42f": "Calendar source type",
     "i18n:govoplan-calendar.calendar_views.9e6b9c2b": "Calendar views",
     "i18n:govoplan-calendar.calendar.adab5090": "Calendar",
+    "i18n:govoplan-calendar.calendars_are_unavailable.f074c862": "Calendars are unavailable.",
     "i18n:govoplan-calendar.calendars.94445018": "Calendars",
     "i18n:govoplan-calendar.cancel.77dfd213": "Cancel",
     "i18n:govoplan-calendar.cancelled.5587b0af": "CANCELLED",
@@ -38,7 +39,6 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.confirmed.0542404a": "CONFIRMED",
     "i18n:govoplan-calendar.conflict_policy.5810e150": "Conflict policy",
     "i18n:govoplan-calendar.continuous.04f2ccda": "Continuous",
-    "i18n:govoplan-calendar.credential_reference.a7e92de5": "Credential reference",
     "i18n:govoplan-calendar.credential.8bede3ea": "Credential",
     "i18n:govoplan-calendar.dav_url.4205e180": "DAV URL",
     "i18n:govoplan-calendar.day.987b9ced": "Day",
@@ -46,6 +46,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.delete.f6fdbe48": "Delete",
     "i18n:govoplan-calendar.deleting.2cda36c9": "Deleting",
     "i18n:govoplan-calendar.description.55f8ebc8": "Description",
+    "i18n:govoplan-calendar.detach_local_events_and_keep_remote_events.c58ad4e7": "Detach local events and keep remote events",
     "i18n:govoplan-calendar.direction.fd8e45ba": "Direction",
     "i18n:govoplan-calendar.discover.4827ea22": "Discover",
     "i18n:govoplan-calendar.discovering.1884f689": "Discovering...",
@@ -61,18 +62,21 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.end_date.89d10cd6": "End date",
     "i18n:govoplan-calendar.end_mode.5a06de37": "End mode",
     "i18n:govoplan-calendar.end_time.cd7800da": "End time",
-    "i18n:govoplan-calendar.enter_a_secret_now_or_use_an_environment_referen.6db0e6ce": "Enter a secret now or use an environment reference such as",
+    "i18n:govoplan-calendar.enter_a_password_or_token_for_this_source.74c09a54": "Enter a password or token for this source.",
     "i18n:govoplan-calendar.etag.11d00f6e": "ETag",
     "i18n:govoplan-calendar.event": "event",
     "i18n:govoplan-calendar.event_count_could_not_be_loaded_the_backend_will.163ff055": "Event count could not be loaded. The backend will still apply the selected delete action.",
     "i18n:govoplan-calendar.events": "events",
     "i18n:govoplan-calendar.events_are_stored_in_govoplan_and_are_not_synced.3660e504": "Events are stored in GovOPlaN and are not synced to an external calendar source.",
+    "i18n:govoplan-calendar.events_remain_in_govoplan_no_external_calendar_is_.62cb5937": "Events remain in GovOPlaN; no external calendar is changed.",
     "i18n:govoplan-calendar.ews_endpoint.a3273983": "EWS endpoint",
     "i18n:govoplan-calendar.exchange_web_services_source.53caabf3": "Exchange Web Services source",
     "i18n:govoplan-calendar.exchange.5b13eac7": "Exchange",
     "i18n:govoplan-calendar.exdate_json.7d0c538d": "EXDATE JSON",
     "i18n:govoplan-calendar.fri.bbd6e32e": "Fri",
     "i18n:govoplan-calendar.full_sync.21b89c76": "Full sync",
+    "i18n:govoplan-calendar.govoplan_moves_the_events_locally_and_queues_durab.da075b16": "GovOPlaN moves the events locally and queues durable CalDAV copies. Delivery failures remain visible and retryable.",
+    "i18n:govoplan-calendar.govoplan_moves_the_local_event_copies_to_the_targe.4863e46b": "GovOPlaN moves the local event copies to the target calendar and unlinks this source. The remote calendar and its events remain unchanged.",
     "i18n:govoplan-calendar.graph_calendar_url.e59607f3": "Graph calendar URL",
     "i18n:govoplan-calendar.graph.9a7405eb": "Graph",
     "i18n:govoplan-calendar.icalendar_json.fb6cc33e": "iCalendar JSON",
@@ -85,6 +89,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.last_attempt.82aee111": "Last attempt",
     "i18n:govoplan-calendar.last_sync.ef0ef267": "Last sync",
     "i18n:govoplan-calendar.loading_calendar.7eb8f548": "Loading calendar...",
+    "i18n:govoplan-calendar.loading_calendars.afbb957b": "Loading calendars...",
     "i18n:govoplan-calendar.loading_event_count.716ad3c2": "Loading event count...",
     "i18n:govoplan-calendar.local_calendar.ed3f72f8": "Local calendar",
     "i18n:govoplan-calendar.local.dc99d54d": "Local",
@@ -96,6 +101,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.microsoft_graph_source.ec4f1383": "Microsoft Graph source",
     "i18n:govoplan-calendar.mon.24b2a099": "Mon",
     "i18n:govoplan-calendar.month.082bc378": "Month",
+    "i18n:govoplan-calendar.move_and_copy_events_to_the_external_calendar.23c3a004": "Move and copy events to the external calendar",
     "i18n:govoplan-calendar.move_events_to_another_calendar.830c7b09": "Move events to another calendar",
     "i18n:govoplan-calendar.name.709a2322": "Name",
     "i18n:govoplan-calendar.never.80c3052d": "Never",
@@ -103,9 +109,12 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.new.6403f2b7": "New",
     "i18n:govoplan-calendar.next_sync.88c7af72": "Next sync",
     "i18n:govoplan-calendar.next.bc981983": "Next",
+    "i18n:govoplan-calendar.no_compatible_target_calendar_is_available_add_a_l.1cf6e47b": "No compatible target calendar is available. Add a local calendar or an active two-way CalDAV calendar.",
     "i18n:govoplan-calendar.no_calendar_collections_found.6453624a": "No calendar collections found.",
+    "i18n:govoplan-calendar.no_calendars_are_available.711d2cf3": "No calendars are available.",
     "i18n:govoplan-calendar.no_calendars.3a7e4a7a": "No calendars",
     "i18n:govoplan-calendar.no_events.e339ba73": "No events",
+    "i18n:govoplan-calendar.no_local_target_calendar_is_available_add_a_local_.fad3cb65": "No local target calendar is available. Add a local calendar to detach these events without changing the remote calendar.",
     "i18n:govoplan-calendar.none.6eef6648": "None",
     "i18n:govoplan-calendar.not_configured.811931bb": "Not configured",
     "i18n:govoplan-calendar.not_scheduled.9c367369": "Not scheduled",
@@ -140,6 +149,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.save.efc007a3": "Save",
     "i18n:govoplan-calendar.saving.ae7e8875": "Saving...",
     "i18n:govoplan-calendar.sequence.5c8f4e0e": "Sequence",
+    "i18n:govoplan-calendar.select_calendar.f38b5ba2": "Select calendar",
     "i18n:govoplan-calendar.show_value.60e2ce8e": "Show {value0}",
     "i18n:govoplan-calendar.source_href.819fa147": "Source href",
     "i18n:govoplan-calendar.source_kind.7eda9bc4": "Source kind",
@@ -158,6 +168,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.target_calendar.e533fe1d": "Target calendar",
     "i18n:govoplan-calendar.tentative.d19f9022": "TENTATIVE",
     "i18n:govoplan-calendar.the_selected_calendar.67caa12f": "the selected calendar",
+    "i18n:govoplan-calendar.the_selected_calendar_is_no_longer_available.39f0f1f5": "The selected calendar is no longer available.",
     "i18n:govoplan-calendar.thu.3593ccd9": "Thu",
     "i18n:govoplan-calendar.timezone.d1f7dc89": "Timezone",
     "i18n:govoplan-calendar.title.768e0c1c": "Title",
@@ -201,6 +212,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.calendar_source_type.92cdb42f": "Calendar source type",
     "i18n:govoplan-calendar.calendar_views.9e6b9c2b": "Calendar views",
     "i18n:govoplan-calendar.calendar.adab5090": "Kalender",
+    "i18n:govoplan-calendar.calendars_are_unavailable.f074c862": "Kalender sind nicht verfügbar.",
     "i18n:govoplan-calendar.calendars.94445018": "Calendars",
     "i18n:govoplan-calendar.cancel.77dfd213": "Abbrechen",
     "i18n:govoplan-calendar.cancelled.5587b0af": "CANCELLED",
@@ -215,7 +227,6 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.confirmed.0542404a": "CONFIRMED",
     "i18n:govoplan-calendar.conflict_policy.5810e150": "Conflict policy",
     "i18n:govoplan-calendar.continuous.04f2ccda": "Continuous",
-    "i18n:govoplan-calendar.credential_reference.a7e92de5": "Credential reference",
     "i18n:govoplan-calendar.credential.8bede3ea": "Credential",
     "i18n:govoplan-calendar.dav_url.4205e180": "DAV URL",
     "i18n:govoplan-calendar.day.987b9ced": "Tag",
@@ -223,6 +234,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.delete.f6fdbe48": "Löschen",
     "i18n:govoplan-calendar.deleting.2cda36c9": "Deleting",
     "i18n:govoplan-calendar.description.55f8ebc8": "Beschreibung",
+    "i18n:govoplan-calendar.detach_local_events_and_keep_remote_events.c58ad4e7": "Lokale Termine abtrennen und entfernte Termine beibehalten",
     "i18n:govoplan-calendar.direction.fd8e45ba": "Direction",
     "i18n:govoplan-calendar.discover.4827ea22": "Discover",
     "i18n:govoplan-calendar.discovering.1884f689": "Discovering...",
@@ -238,18 +250,21 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.end_date.89d10cd6": "End date",
     "i18n:govoplan-calendar.end_mode.5a06de37": "End mode",
     "i18n:govoplan-calendar.end_time.cd7800da": "End time",
-    "i18n:govoplan-calendar.enter_a_secret_now_or_use_an_environment_referen.6db0e6ce": "Enter a secret now or use an environment reference such as",
+    "i18n:govoplan-calendar.enter_a_password_or_token_for_this_source.74c09a54": "Geben Sie ein Passwort oder Token für diese Quelle ein.",
     "i18n:govoplan-calendar.etag.11d00f6e": "ETag",
     "i18n:govoplan-calendar.event": "event",
     "i18n:govoplan-calendar.event_count_could_not_be_loaded_the_backend_will.163ff055": "Event count could not be loaded. The backend will still apply the selected delete action.",
     "i18n:govoplan-calendar.events": "events",
     "i18n:govoplan-calendar.events_are_stored_in_govoplan_and_are_not_synced.3660e504": "Events are stored in GovOPlaN and are not synced to an external calendar source.",
+    "i18n:govoplan-calendar.events_remain_in_govoplan_no_external_calendar_is_.62cb5937": "Die Termine bleiben in GovOPlaN; kein externer Kalender wird geändert.",
     "i18n:govoplan-calendar.ews_endpoint.a3273983": "EWS endpoint",
     "i18n:govoplan-calendar.exchange_web_services_source.53caabf3": "Exchange Web Services source",
     "i18n:govoplan-calendar.exchange.5b13eac7": "Exchange",
     "i18n:govoplan-calendar.exdate_json.7d0c538d": "EXDATE JSON",
     "i18n:govoplan-calendar.fri.bbd6e32e": "Fri",
     "i18n:govoplan-calendar.full_sync.21b89c76": "Full sync",
+    "i18n:govoplan-calendar.govoplan_moves_the_events_locally_and_queues_durab.da075b16": "GovOPlaN verschiebt die Termine lokal und reiht dauerhafte CalDAV-Kopien ein. Zustellfehler bleiben sichtbar und können erneut versucht werden.",
+    "i18n:govoplan-calendar.govoplan_moves_the_local_event_copies_to_the_targe.4863e46b": "GovOPlaN verschiebt die lokalen Terminkopien in den Zielkalender und trennt diese Quelle. Der entfernte Kalender und seine Termine bleiben unverändert.",
     "i18n:govoplan-calendar.graph_calendar_url.e59607f3": "Graph calendar URL",
     "i18n:govoplan-calendar.graph.9a7405eb": "Graph",
     "i18n:govoplan-calendar.icalendar_json.fb6cc33e": "iCalendar JSON",
@@ -262,6 +277,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.last_attempt.82aee111": "Last attempt",
     "i18n:govoplan-calendar.last_sync.ef0ef267": "Last sync",
     "i18n:govoplan-calendar.loading_calendar.7eb8f548": "Loading calendar...",
+    "i18n:govoplan-calendar.loading_calendars.afbb957b": "Kalender werden geladen...",
     "i18n:govoplan-calendar.loading_event_count.716ad3c2": "Loading event count...",
     "i18n:govoplan-calendar.local_calendar.ed3f72f8": "Local calendar",
     "i18n:govoplan-calendar.local.dc99d54d": "Local",
@@ -273,16 +289,20 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.microsoft_graph_source.ec4f1383": "Microsoft Graph source",
     "i18n:govoplan-calendar.mon.24b2a099": "Mon",
     "i18n:govoplan-calendar.month.082bc378": "Monat",
-    "i18n:govoplan-calendar.move_events_to_another_calendar.830c7b09": "Move events to another calendar",
+    "i18n:govoplan-calendar.move_and_copy_events_to_the_external_calendar.23c3a004": "Termine verschieben und in den externen Kalender kopieren",
+    "i18n:govoplan-calendar.move_events_to_another_calendar.830c7b09": "Termine in einen anderen Kalender verschieben",
     "i18n:govoplan-calendar.name.709a2322": "Name",
     "i18n:govoplan-calendar.never.80c3052d": "Never",
     "i18n:govoplan-calendar.new_event.2ef3795c": "New event",
     "i18n:govoplan-calendar.new.6403f2b7": "New",
     "i18n:govoplan-calendar.next_sync.88c7af72": "Next sync",
     "i18n:govoplan-calendar.next.bc981983": "Weiter",
+    "i18n:govoplan-calendar.no_compatible_target_calendar_is_available_add_a_l.1cf6e47b": "Kein kompatibler Zielkalender ist verfügbar. Fügen Sie einen lokalen Kalender oder einen aktiven CalDAV-Kalender mit bidirektionaler Synchronisierung hinzu.",
     "i18n:govoplan-calendar.no_calendar_collections_found.6453624a": "No calendar collections found.",
+    "i18n:govoplan-calendar.no_calendars_are_available.711d2cf3": "Es sind keine Kalender verfügbar.",
     "i18n:govoplan-calendar.no_calendars.3a7e4a7a": "No calendars",
     "i18n:govoplan-calendar.no_events.e339ba73": "No events",
+    "i18n:govoplan-calendar.no_local_target_calendar_is_available_add_a_local_.fad3cb65": "Kein lokaler Zielkalender ist verfügbar. Fügen Sie einen lokalen Kalender hinzu, um diese Termine abzutrennen, ohne den entfernten Kalender zu ändern.",
     "i18n:govoplan-calendar.none.6eef6648": "Keine",
     "i18n:govoplan-calendar.not_configured.811931bb": "Nicht konfiguriert",
     "i18n:govoplan-calendar.not_scheduled.9c367369": "Not scheduled",
@@ -317,6 +337,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.save.efc007a3": "Speichern",
     "i18n:govoplan-calendar.saving.ae7e8875": "Saving...",
     "i18n:govoplan-calendar.sequence.5c8f4e0e": "Sequence",
+    "i18n:govoplan-calendar.select_calendar.f38b5ba2": "Kalender auswählen",
     "i18n:govoplan-calendar.show_value.60e2ce8e": "Show {value0}",
     "i18n:govoplan-calendar.source_href.819fa147": "Source href",
     "i18n:govoplan-calendar.source_kind.7eda9bc4": "Source kind",
@@ -335,6 +356,7 @@ export const generatedTranslations: PlatformTranslations = {
     "i18n:govoplan-calendar.target_calendar.e533fe1d": "Target calendar",
     "i18n:govoplan-calendar.tentative.d19f9022": "TENTATIVE",
     "i18n:govoplan-calendar.the_selected_calendar.67caa12f": "the selected calendar",
+    "i18n:govoplan-calendar.the_selected_calendar_is_no_longer_available.39f0f1f5": "Der ausgewählte Kalender ist nicht mehr verfügbar.",
     "i18n:govoplan-calendar.thu.3593ccd9": "Thu",
     "i18n:govoplan-calendar.timezone.d1f7dc89": "Timezone",
     "i18n:govoplan-calendar.title.768e0c1c": "Title",

webui/src/index.ts

@@ -1,2 +1,4 @@
 export { calendarModule as default, calendarModule } from "./module";
 export * from "./api/calendar";
+export { default as CalendarPicker } from "./features/calendar/CalendarPicker";
+export * from "./features/calendar/calendarPickerLogic";

webui/src/module.ts

@@ -1,7 +1,8 @@
 import { createElement, lazy } from "react";
-import type { PlatformWebModule } from "@govoplan/core-webui";
+import type { CalendarPickerUiCapability, PlatformWebModule } from "@govoplan/core-webui";
 import "./styles/calendar.css";
 import { generatedTranslations } from "./i18n/generatedTranslations";
+import CalendarPicker from "./features/calendar/CalendarPicker";
 
 const CalendarPage = lazy(() => import("./features/calendar/CalendarPage"));
 
@@ -11,6 +12,8 @@ const translations = {
   de: generatedTranslations.de
 };
 
+const calendarPicker: CalendarPickerUiCapability = { CalendarPicker };
+
 export const calendarModule: PlatformWebModule = {
   id: "calendar",
   label: "i18n:govoplan-calendar.calendar.adab5090",
@@ -20,7 +23,10 @@ export const calendarModule: PlatformWebModule = {
   translations,
   navItems: [{ to: "/calendar", label: "i18n:govoplan-calendar.calendar.adab5090", iconName: "calendar", anyOf: eventRead, order: 55 }],
   routes: [
-  { path: "/calendar", anyOf: eventRead, order: 55, render: ({ settings, auth }) => createElement(CalendarPage, { settings, auth }) }]
+  { path: "/calendar", anyOf: eventRead, order: 55, render: ({ settings, auth }) => createElement(CalendarPage, { settings, auth }) }],
+  uiCapabilities: {
+    "calendar.picker": calendarPicker
+  }
 
 };
 

webui/src/styles/calendar.css

@@ -28,7 +28,7 @@
   display: grid;
   grid-template-columns: minmax(240px, 300px) minmax(0, 1fr);
   overflow: hidden;
-  border: 1px solid var(--line);
+  border: var(--border-line);
   border-radius: 0;
   background: var(--panel);
 }
@@ -51,7 +51,7 @@
   align-items: center;
   gap: 14px;
   padding: 10px 14px;
-  border-bottom: 1px solid var(--line);
+  border-bottom: var(--border-line);
   background: var(--panel-header);
 }
 
@@ -89,21 +89,6 @@
   gap: 6px;
 }
 
-.calendar-icon-button.btn {
-  width: 36px;
-  min-width: 36px;
-  height: 36px;
-  display: inline-flex;
-  align-items: center;
-  justify-content: center;
-  padding: 0;
-}
-
-.calendar-icon-button.btn:disabled {
-  opacity: .42;
-  cursor: default;
-}
-
 .calendar-mode-switch {
   flex: 0 1 520px;
   grid-template-columns: repeat(5, minmax(0, 1fr));
@@ -121,14 +106,14 @@
   display: flex;
   flex-direction: column;
   overflow: hidden;
-  border-right: 1px solid var(--line);
+  border-right: var(--border-line);
   background: linear-gradient(180deg, var(--panel-soft), var(--panel));
 }
 
 .calendar-sidebar-heading {
   flex: 0 0 auto;
   padding: 13px 14px;
-  border-bottom: 1px solid var(--line);
+  border-bottom: var(--border-line);
   color: var(--muted);
   font-size: 12px;
   font-weight: 800;
@@ -137,7 +122,7 @@
 }
 
 .calendar-sidebar-heading.is-secondary {
-  border-top: 1px solid var(--line);
+  border-top: var(--border-line);
 }
 
 .calendar-list,
@@ -201,9 +186,9 @@
   display: inline-flex;
   align-items: center;
   padding: 2px;
-  border: 1px solid #c9c3b9;
+  border: 1px solid var(--control-border);
   border-radius: 999px;
-  background: #d8d3cb;
+  background: var(--calendar-switch-bg);
   cursor: pointer;
   transition: background .16s ease, border-color .16s ease;
 }
@@ -217,8 +202,8 @@
   width: 14px;
   height: 14px;
   border-radius: 50%;
-  background: #fff;
+  background: var(--surface);
-  box-shadow: 0 1px 2px rgba(0, 0, 0, .18);
+  box-shadow: var(--shadow-thumb);
   transform: translateX(0);
   transition: transform .16s ease;
 }
@@ -250,40 +235,7 @@
 }
 
 .calendar-list-actions {
-  display: flex;
+  width: auto;
-  align-items: center;
-  justify-content: flex-end;
-  gap: 2px;
-  min-width: 28px;
-}
-
-.calendar-row-icon-button.btn {
-  width: 28px;
-  min-width: 28px;
-  height: 28px;
-  display: inline-flex;
-  align-items: center;
-  justify-content: center;
-  padding: 0;
-  border-color: transparent;
-  background: transparent;
-  opacity: .72;
-}
-
-.calendar-row-icon-button.btn:hover,
-.calendar-row-icon-button.btn:focus-visible {
-  border-color: var(--line-dark);
-  background: var(--surface);
-  opacity: 1;
-}
-
-.calendar-row-icon-button.btn.is-syncing,
-.calendar-row-icon-button.btn.is-syncing:disabled {
-  border-color: var(--green);
-  background: var(--surface);
-  color: var(--green);
-  opacity: 1;
-  cursor: progress;
 }
 
 .calendar-sync-spin {
@@ -306,7 +258,7 @@
   min-width: 0;
   margin-top: 6px;
   padding-top: 8px;
-  border-top: 1px solid var(--line);
+  border-top: var(--border-line);
 }
 
 .calendar-create-action .btn {
@@ -331,7 +283,7 @@
 .calendar-agenda-group + .calendar-agenda-group {
   margin-top: 8px;
   padding-top: 8px;
-  border-top: 1px solid var(--line);
+  border-top: var(--border-line);
 }
 
 .calendar-agenda-group h3 {
@@ -346,15 +298,15 @@
 
 .calendar-agenda-item {
   --calendar-event-color: var(--green);
-  --calendar-event-bg: #edf8f5;
+  --calendar-event-bg: var(--calendar-event-bg-default);
-  --calendar-event-border: #b9d7d0;
+  --calendar-event-border: var(--calendar-event-border-default);
   display: block;
   min-height: 28px;
   padding: 5px 7px;
   border: 1px solid var(--calendar-event-border);
   border-left: 4px solid var(--calendar-event-color, var(--green));
   background: var(--calendar-event-bg);
-  color: #21453e;
+  color: var(--calendar-event-text);
 }
 
 .calendar-agenda-item strong {
@@ -369,7 +321,7 @@
 .calendar-agenda-item .calendar-event-separator,
 .calendar-agenda p {
   margin: 0;
-  color: #4d6764;
+  color: var(--calendar-event-muted-text);
   font-size: 12px;
 }
 
@@ -401,9 +353,9 @@
   inset: 0 auto auto 0;
   z-index: 4;
   padding: 10px;
-  border-right: 1px solid var(--line);
+  border-right: var(--border-line);
-  border-bottom: 1px solid var(--line);
+  border-bottom: var(--border-line);
-  background: rgba(255, 255, 255, 0.9);
+  background: var(--panel-glass-bright);
 }
 
 .calendar-week-rows {
@@ -439,7 +391,7 @@
   top: 0;
   z-index: 2;
   flex: 0 0 auto;
-  border-bottom: 1px solid var(--line-dark);
+  border-bottom: var(--border-line-dark);
   background: var(--panel);
 }
 
@@ -459,7 +411,7 @@
 
 .calendar-week-row {
   min-height: 132px;
-  border-bottom: 1px solid var(--line);
+  border-bottom: var(--border-line);
 }
 
 .calendar-week-rows.is-continuous .calendar-week-row {
@@ -476,22 +428,22 @@
   flex-direction: column;
   gap: 6px;
   padding: 8px;
-  border-right: 1px solid var(--line);
+  border-right: var(--border-line);
   background: var(--surface);
   overflow: hidden;
 }
 
 .calendar-day-cell.is-even-month {
-  background: #ffffff;
+  background: var(--surface);
 }
 
 .calendar-day-cell.is-odd-month {
-  background: #f8f6f2;
+  background: var(--calendar-grid-bg);
 }
 
 .calendar-day-cell.is-muted {
-  color: #8a8278;
+  color: var(--muted);
-  background: #f1efeb;
+  background: var(--control-gradient-end-muted);
 }
 
 .calendar-day-cell.is-today {
@@ -499,7 +451,7 @@
 }
 
 .calendar-day-cell.is-drop-target {
-  background: #e3f3ef;
+  background: var(--calendar-today-bg);
   box-shadow: inset 0 0 0 2px var(--green);
 }
 
@@ -535,8 +487,8 @@
 
 .calendar-event-chip {
   --calendar-event-color: var(--green);
-  --calendar-event-bg: #edf8f5;
+  --calendar-event-bg: var(--calendar-event-bg-default);
-  --calendar-event-border: #b9d7d0;
+  --calendar-event-border: var(--calendar-event-border-default);
   min-width: 0;
   min-height: 26px;
   display: block;
@@ -545,7 +497,7 @@
   border-left: 4px solid var(--calendar-event-color);
   border-radius: 4px;
   background: var(--calendar-event-bg);
-  color: #21453e;
+  color: var(--calendar-event-text);
   cursor: pointer;
   font: inherit;
   font-size: 12px;
@@ -597,7 +549,7 @@
 .calendar-event-time,
 .calendar-event-separator {
   flex: 0 0 auto;
-  color: #4d6764;
+  color: var(--calendar-event-muted-text);
 }
 
 .calendar-more-events {
@@ -635,8 +587,8 @@
 .calendar-time-corner,
 .calendar-all-day-label,
 .calendar-all-day-cell {
-  border-bottom: 1px solid var(--line-dark);
+  border-bottom: var(--border-line-dark);
-  border-right: 1px solid var(--line);
+  border-right: var(--border-line);
   background: var(--panel);
 }
 
@@ -649,12 +601,12 @@
 }
 
 .calendar-time-header > header.is-today {
-  background: #e0f0ea;
+  background: var(--calendar-selected-bg);
 }
 
 .calendar-time-header > header.is-weekend,
 .calendar-all-day-cell.is-weekend {
-  background: #f1efeb;
+  background: var(--control-gradient-end-muted);
 }
 
 .calendar-time-header > header span {
@@ -665,7 +617,7 @@
 .calendar-all-day-strip {
   flex: 0 0 auto;
   min-height: 42px;
-  border-bottom: 1px solid var(--line-dark);
+  border-bottom: var(--border-line-dark);
 }
 
 .calendar-all-day-label {
@@ -683,7 +635,7 @@
 }
 
 .calendar-all-day-cell.is-drop-target {
-  background: #e3f3ef;
+  background: var(--calendar-today-bg);
   box-shadow: inset 0 0 0 2px var(--green);
 }
 
@@ -712,8 +664,8 @@
 
 .calendar-hour-label {
   min-height: 64px;
-  border-bottom: 1px solid var(--line);
+  border-bottom: var(--border-line);
-  border-right: 1px solid var(--line);
+  border-right: var(--border-line);
   padding: 8px;
   color: var(--muted);
   font-size: 12px;
@@ -724,17 +676,17 @@
   position: relative;
   height: 1536px;
   min-height: 1536px;
-  border-right: 1px solid var(--line);
+  border-right: var(--border-line);
   background:
     linear-gradient(to bottom, var(--calendar-day-shade), var(--calendar-day-shade)),
     linear-gradient(
       to bottom,
-      rgba(241, 239, 235, var(--calendar-off-hours-opacity)) 0,
+      rgba(var(--calendar-off-hours-rgb), var(--calendar-off-hours-opacity)) 0,
-      rgba(241, 239, 235, var(--calendar-off-hours-opacity)) var(--calendar-work-start-y),
+      rgba(var(--calendar-off-hours-rgb), var(--calendar-off-hours-opacity)) var(--calendar-work-start-y),
       transparent var(--calendar-work-start-y),
       transparent var(--calendar-work-end-y),
-      rgba(241, 239, 235, var(--calendar-off-hours-opacity)) var(--calendar-work-end-y),
+      rgba(var(--calendar-off-hours-rgb), var(--calendar-off-hours-opacity)) var(--calendar-work-end-y),
-      rgba(241, 239, 235, var(--calendar-off-hours-opacity)) 100%
+      rgba(var(--calendar-off-hours-rgb), var(--calendar-off-hours-opacity)) 100%
     ),
     repeating-linear-gradient(
       to bottom,
@@ -746,11 +698,11 @@
 }
 
 .calendar-day-time-column.is-weekend {
-  --calendar-day-shade: rgba(241, 239, 235, .74);
+  --calendar-day-shade: var(--calendar-day-shade);
 }
 
 .calendar-day-time-column.is-drop-target {
-  box-shadow: inset 0 0 0 2px rgba(90, 169, 155, .55);
+  box-shadow: var(--calendar-focus-inset);
 }
 
 .calendar-time-drop-marker {
@@ -778,10 +730,10 @@
   top: -13px;
   left: 10px;
   padding: 2px 6px;
-  border: 1px solid #4f9489;
+  border: 1px solid var(--calendar-success-border);
   border-radius: 4px;
   background: var(--green);
-  color: #fff;
+  color: var(--on-accent);
   font-size: 11px;
   font-weight: 800;
   line-height: 1.2;
@@ -799,15 +751,15 @@
 
 .calendar-timed-event {
   --calendar-event-color: var(--green);
-  --calendar-event-bg: #edf8f5;
+  --calendar-event-bg: var(--calendar-event-bg-default);
-  --calendar-event-border: #b9d7d0;
+  --calendar-event-border: var(--calendar-event-border-default);
   display: block;
   padding: 0;
   overflow: hidden;
   border: 1px solid var(--calendar-event-border);
   border-left: 4px solid var(--calendar-event-color);
   background: var(--calendar-event-bg);
-  color: #21453e;
+  color: var(--calendar-event-text);
   cursor: pointer;
   font-size: 12px;
 }
@@ -817,8 +769,8 @@
 .calendar-timed-event.is-linked-hover,
 .calendar-timed-overflow:hover,
 .calendar-timed-overflow:focus-visible {
-  border-color: var(--calendar-event-color, #5aa99b);
+  border-color: var(--calendar-event-color, var(--success-border));
-  background: var(--calendar-event-bg, #e3f3ef);
+  background: var(--calendar-event-bg, var(--calendar-today-bg));
   outline: none;
 }
 
@@ -837,7 +789,7 @@
 }
 
 .calendar-timed-event-content:focus-visible {
-  outline: 2px solid rgba(90, 169, 155, .35);
+  outline: var(--calendar-focus-outline);
   outline-offset: -2px;
 }
 
@@ -864,7 +816,7 @@
   width: 34px;
   height: 2px;
   border-radius: 999px;
-  background: rgba(33, 69, 62, .46);
+  background: var(--calendar-overlay);
   content: "";
   opacity: 0;
   transform: translateX(-50%);
@@ -890,7 +842,7 @@
   height: 28px;
   display: grid;
   place-items: center;
-  border: 1px solid var(--line-dark);
+  border: var(--border-line-dark);
   background: var(--panel-soft);
   color: var(--text-strong);
   cursor: pointer;
@@ -963,7 +915,7 @@
   display: grid;
   gap: 12px;
   padding: 12px;
-  border: 1px solid var(--line);
+  border: var(--border-line);
   border-radius: 6px;
   background: var(--panel-soft);
 }
@@ -1051,7 +1003,7 @@
 }
 
 .calendar-vevent-details {
-  border-top: 1px solid var(--line);
+  border-top: var(--border-line);
   padding-top: 4px;
 }
 
@@ -1059,7 +1011,7 @@
   display: grid;
   gap: 10px;
   padding: 12px 0;
-  border-top: 1px solid var(--line);
+  border-top: var(--border-line);
 }
 
 .calendar-vevent-section:first-of-type {
@@ -1085,7 +1037,7 @@
 
 .calendar-sync-status {
   padding: 3px 8px;
-  border: 1px solid var(--line-dark);
+  border: var(--border-line-dark);
   border-radius: 999px;
   background: var(--surface);
   color: var(--muted);
@@ -1094,8 +1046,8 @@
 }
 
 .calendar-sync-status.is-error {
-  border-color: #f0b8b2;
+  border-color: var(--calendar-danger-border);
-  background: #fff2f0;
+  background: var(--calendar-danger-bg);
   color: var(--red);
 }
 
@@ -1115,7 +1067,7 @@
   display: grid;
   gap: 10px;
   padding: 10px;
-  border: 1px solid var(--line);
+  border: var(--border-line);
   border-radius: 6px;
   background: var(--surface);
 }
@@ -1150,9 +1102,9 @@
 .calendar-form-error {
   margin: 0;
   padding: 9px 10px;
-  border: 1px solid #f0b8b2;
+  border: 1px solid var(--calendar-danger-border);
   border-radius: 4px;
-  background: #fff2f0;
+  background: var(--calendar-danger-bg);
   color: var(--red);
   font-size: 13px;
 }
@@ -1166,13 +1118,13 @@
 }
 
 .calendar-delete-warning {
-  border: 1px solid #f0b8b2;
+  border: 1px solid var(--calendar-danger-border);
-  background: #fff2f0;
+  background: var(--calendar-danger-bg);
   color: var(--red);
 }
 
 .calendar-form-note {
-  border: 1px solid var(--line);
+  border: var(--border-line);
   background: var(--panel-soft);
   color: var(--muted);
 }
@@ -1182,7 +1134,7 @@
   gap: 10px;
   margin: 0;
   padding: 10px;
-  border: 1px solid var(--line);
+  border: var(--border-line);
   border-radius: 6px;
   background: var(--panel-soft);
 }
@@ -1275,7 +1227,7 @@
 
   .calendar-sidebar {
     border-right: 0;
-    border-bottom: 1px solid var(--line);
+    border-bottom: var(--border-line);
   }
 
   .calendar-mode-switch {

webui/tests/calendar-picker-structure.test.mjs

@@ -0,0 +1,20 @@
+import fs from "node:fs";
+
+function assert(condition, message) {
+  if (!condition) throw new Error(message);
+}
+
+const picker = fs.readFileSync(new URL("../src/features/calendar/CalendarPicker.tsx", import.meta.url), "utf8");
+const moduleSource = fs.readFileSync(new URL("../src/module.ts", import.meta.url), "utf8");
+const coreTypes = fs.readFileSync(new URL("../../../govoplan-core/webui/src/types.ts", import.meta.url), "utf8");
+
+assert(moduleSource.includes('"calendar.picker": calendarPicker'), "Calendar must register the named picker capability");
+assert(coreTypes.includes("export type CalendarPickerUiCapability"), "Core must expose the narrow cross-module contract");
+assert(picker.includes("listCalendars(settings)"), "Picker must use Calendar's authenticated list API");
+assert(picker.includes("hasScope(auth, CALENDAR_PICKER_READ_SCOPE)"), "Picker must avoid loading without read permission");
+assert(picker.includes("value={value}"), "Picker must remain controlled by its consumer");
+assert(picker.includes("onChange={(event) => onChange(event.target.value)}"), "Picker must return the chosen calendar id");
+assert(picker.includes("aria-busy={loading || undefined}"), "Picker must expose loading state accessibly");
+assert(picker.includes("aria-describedby={status ? statusId : undefined}"), "Picker must associate availability feedback");
+
+console.log("Calendar picker capability structure checks passed.");

webui/tests/calendar-picker.test.ts

@@ -0,0 +1,37 @@
+import {
+  calendarPickerOptions,
+  calendarPickerTenantId,
+  type CalendarPickerOption
+} from "../src/features/calendar/calendarPickerLogic";
+
+function assert(condition: unknown, message: string): void {
+  if (!condition) throw new Error(message);
+}
+
+function calendar(id: string, name: string, isDefault = false): CalendarPickerOption {
+  return {
+    id,
+    name,
+    is_default: isDefault
+  };
+}
+
+const input = [
+  calendar("z", "Zulu"),
+  calendar("b", "Bravo", true),
+  calendar("a", "alpha")
+];
+const ordered = calendarPickerOptions(input);
+
+assert(ordered.map((item) => item.id).join(",") === "b,a,z", "default calendar should lead, followed by names");
+assert(input.map((item) => item.id).join(",") === "z,b,a", "picker sorting must not mutate API data");
+assert(
+  calendarPickerTenantId({ tenant: { id: "fallback" }, active_tenant: { id: "active" } }) === "active",
+  "active tenant should partition picker requests"
+);
+assert(
+  calendarPickerTenantId({ tenant: { id: "fallback" } }) === "fallback",
+  "legacy tenant should remain a supported fallback"
+);
+
+console.log("Calendar picker behavior checks passed.");

webui/tsconfig.calendar-picker-tests.json

@@ -0,0 +1,18 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "lib": ["ES2020", "DOM"],
+    "strict": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "module": "CommonJS",
+    "moduleResolution": "Node",
+    "noEmit": false,
+    "outDir": ".calendar-picker-test-build",
+    "rootDir": "."
+  },
+  "include": [
+    "tests/calendar-picker.test.ts",
+    "src/features/calendar/calendarPickerLogic.ts"
+  ]
+}