docs: define CalDAV secret retirement

.gitignore

@@ -8,3 +8,271 @@ __pycache__/
 node_modules/
 dist/
 webui/dist/
+
+# GovOPlaN shared ignore rules from govoplan-core
+# ---> Node
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+.pnpm-debug.log*
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+# Coverage directory used by tools like istanbul
+coverage
+*.lcov
+# nyc test coverage
+.nyc_output
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+# Bower dependency directory (https://bower.io/)
+bower_components
+# node-waf configuration
+.lock-wscript
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+# Dependency directories
+jspm_packages/
+# Snowpack dependency directory (https://snowpack.dev/)
+web_modules/
+# TypeScript cache
+*.tsbuildinfo
+# Optional npm cache directory
+.npm
+# Optional eslint cache
+.eslintcache
+# Optional stylelint cache
+.stylelintcache
+# Microbundle cache
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+# Optional REPL history
+.node_repl_history
+# Output of 'npm pack'
+*.tgz
+# Yarn Integrity file
+.yarn-integrity
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+.parcel-cache
+# Next.js build output
+.next
+out
+# Nuxt.js build / generate output
+.nuxt
+dist
+# Gatsby files
+.cache/
+# Comment in the public line in if your project uses Gatsby and not Next.js
+# https://nextjs.org/blog/next-9-1#public-directory-support
+# public
+# vuepress build output
+.vuepress/dist
+# vuepress v2.x temp and cache directory
+.temp
+.cache
+# vitepress build output
+**/.vitepress/dist
+# vitepress cache directory
+**/.vitepress/cache
+# Docusaurus cache and generated files
+.docusaurus
+# Serverless directories
+.serverless/
+# FuseBox cache
+.fusebox/
+# DynamoDB Local files
+.dynamodb/
+# TernJS port file
+.tern-port
+# Stores VSCode versions used for testing VSCode extensions
+.vscode-test
+# yarn v2
+.yarn/cache
+.yarn/unplugged
+.yarn/build-state.yml
+.yarn/install-state.gz
+.pnp.*
+# Local WebUI test/build scratch directories
+.component-test-build/
+.module-test-build/
+.policy-test-build/
+.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/
+webui/.import-test-build/
+# ---> Python
+# Byte-compiled / optimized / DLL files
+*$py.class
+# C extensions
+*.so
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+.installed.cfg
+*.egg
+MANIFEST
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+cover/
+# Translations
+*.mo
+*.pot
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+# Flask stuff:
+instance/
+.webassets-cache
+# Scrapy stuff:
+.scrapy
+# Sphinx documentation
+docs/_build/
+# PyBuilder
+.pybuilder/
+target/
+# Jupyter Notebook
+.ipynb_checkpoints
+# IPython
+profile_default/
+ipython_config.py
+# pyenv
+#   For a library or package, you might want to ignore these files since the code is
+#   intended to run in multiple environments; otherwise, check them in:
+# .python-version
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+# UV
+#   Similar to Pipfile.lock, it is generally recommended to include uv.lock in version control.
+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#uv.lock
+# poetry
+#   Similar to Pipfile.lock, it is generally recommended to include poetry.lock in version control.
+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
+#poetry.lock
+# pdm
+#   Similar to Pipfile.lock, it is generally recommended to include pdm.lock in version control.
+#pdm.lock
+#   pdm stores project-wide configurations in .pdm.toml, but it is recommended to not include it
+#   in version control.
+#   https://pdm.fming.dev/latest/usage/project/#working-with-version-control
+.pdm.toml
+.pdm-python
+.pdm-build/
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
+__pypackages__/
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+# SageMath parsed files
+*.sage.py
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+# Spyder project settings
+.spyderproject
+.spyproject
+# Rope project settings
+.ropeproject
+# mkdocs documentation
+/site
+# mypy
+.dmypy.json
+dmypy.json
+# Pyre type checker
+.pyre/
+# pytype static type analyzer
+.pytype/
+# Cython debug symbols
+cython_debug/
+# PyCharm
+#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+#.idea/
+# Ruff stuff:
+# PyPI configuration file
+.pypirc
+# ---> VisualStudioCode
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+!.vscode/*.code-snippets
+# Local History for Visual Studio Code
+.history/
+# Built Visual Studio Code Extensions
+*.vsix
+*.db
+# GovOPlaN local runtime state
+runtime/
+# GovOPlaN WebUI test output
+webui/.module-test-build/
+webui/.component-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": "0.1.5",
+  "version": "0.1.8",
   "private": true,
   "type": "module",
   "main": "webui/src/index.ts",
@@ -19,8 +19,8 @@
     "LICENSE"
   ],
   "peerDependencies": {
-    "@govoplan/core-webui": "^0.1.5",
+    "@govoplan/core-webui": "^0.1.9",
-    "lucide-react": "^0.555.0",
+    "lucide-react": "^1.23.0",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
     "react-router-dom": "^7.1.1",

pyproject.toml

@@ -4,15 +4,16 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "govoplan-calendar"
-version = "0.1.5"
+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>=0.1.5",
+  "govoplan-core>=0.1.9",
-  "govoplan-access>=0.1.5",
+  "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):
@@ -21,6 +29,10 @@ class CalDAVPreconditionFailed(CalDAVError):
     pass
 
 
+class CalDAVNotFound(CalDAVError):
+    pass
+
+
 class CalDAVTransport(Protocol):
     def __call__(self, method: str, url: str, headers: Mapping[str, str], body: bytes | None, timeout: int) -> tuple[int, Mapping[str, str], bytes]:
         ...
@@ -48,6 +60,41 @@ class CalDAVWriteResult:
     status: int = 0
 
 
+@dataclass(frozen=True, slots=True)
+class CalDAVDiscoveryCalendar:
+    collection_url: str
+    href: str
+    display_name: str | None = None
+    color: str | None = None
+    ctag: str | None = None
+    sync_token: str | None = None
+
+
+@dataclass(frozen=True, slots=True)
+class _DAVDiscoveryResponse:
+    href: str
+    display_name: str | None = None
+    color: str | None = None
+    ctag: str | None = None
+    sync_token: str | None = None
+    is_calendar: bool = False
+    principal_hrefs: tuple[str, ...] = ()
+    calendar_home_set_hrefs: tuple[str, ...] = ()
+    supported_components: tuple[str, ...] = ()
+
+
+@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,
@@ -78,6 +125,96 @@ class CalDAVClient:
         payload = self.request("PROPFIND", self.collection_url, body=body, depth="0", expected={207})
         return parse_multistatus(payload)
 
+    def discover_calendars(self) -> list[CalDAVDiscoveryCalendar]:
+        start_url = self.collection_url
+        calendars: dict[str, CalDAVDiscoveryCalendar] = {}
+        home_urls: list[str] = []
+        principal_urls: list[str] = []
+        visited_urls: set[tuple[str, str]] = set()
+        errors: list[str] = []
+
+        def add_home_href(base_url: str, href: str) -> None:
+            url = ensure_collection_url(absolute_dav_url(base_url, href))
+            if url not in home_urls:
+                home_urls.append(url)
+
+        def add_principal_href(base_url: str, href: str) -> None:
+            url = ensure_collection_url(absolute_dav_url(base_url, href))
+            if url not in principal_urls:
+                principal_urls.append(url)
+
+        def add_calendar(base_url: str, response: _DAVDiscoveryResponse) -> None:
+            if not response.is_calendar:
+                return
+            if response.supported_components and "VEVENT" not in response.supported_components:
+                return
+            url = ensure_collection_url(absolute_dav_url(base_url, response.href or base_url))
+            calendars[url] = CalDAVDiscoveryCalendar(
+                collection_url=url,
+                href=response.href,
+                display_name=response.display_name,
+                color=response.color,
+                ctag=response.ctag,
+                sync_token=response.sync_token,
+            )
+
+        def propfind(url: str, depth: str) -> list[_DAVDiscoveryResponse]:
+            key = (url, depth)
+            if key in visited_urls:
+                return []
+            visited_urls.add(key)
+            return self.propfind_discovery(url, depth=depth)
+
+        try:
+            for response in propfind(start_url, "0"):
+                add_calendar(start_url, response)
+                for href in response.calendar_home_set_hrefs:
+                    add_home_href(start_url, href)
+                for href in response.principal_hrefs:
+                    add_principal_href(start_url, href)
+        except CalDAVError as exc:
+            errors.append(str(exc))
+
+        for principal_url in principal_urls[:6]:
+            try:
+                for response in propfind(principal_url, "0"):
+                    for href in response.calendar_home_set_hrefs:
+                        add_home_href(principal_url, href)
+            except CalDAVError as exc:
+                errors.append(str(exc))
+
+        if not home_urls:
+            home_urls.append(start_url)
+
+        for home_url in home_urls:
+            try:
+                for response in propfind(home_url, "1"):
+                    add_calendar(home_url, response)
+            except CalDAVError as exc:
+                errors.append(str(exc))
+
+        if not calendars and errors:
+            raise CalDAVError(f"CalDAV discovery did not find any calendar collections: {errors[0]}")
+        return sorted(calendars.values(), key=lambda item: ((item.display_name or item.collection_url).lower(), item.collection_url))
+
+    def propfind_discovery(self, url: str, *, depth: str) -> list[_DAVDiscoveryResponse]:
+        body = b"""<?xml version="1.0" encoding="utf-8"?>
+<D:propfind xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:CS="http://calendarserver.org/ns/" xmlns:ICAL="http://apple.com/ns/ical/">
+  <D:prop>
+    <D:displayname/>
+    <D:current-user-principal/>
+    <D:principal-URL/>
+    <D:resourcetype/>
+    <D:sync-token/>
+    <C:calendar-home-set/>
+    <C:supported-calendar-component-set/>
+    <CS:getctag/>
+    <ICAL:calendar-color/>
+  </D:prop>
+</D:propfind>"""
+        payload = self.request("PROPFIND", ensure_collection_url(url), body=body, depth=depth, expected={207})
+        return parse_discovery_multistatus(payload)
+
     def list_objects(self) -> CalDAVReportResult:
         body = b"""<?xml version="1.0" encoding="utf-8"?>
 <C:calendar-query xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav">
@@ -111,8 +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"}
@@ -149,7 +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)
@@ -182,6 +348,8 @@ class CalDAVClient:
             headers.update(dict(extra_headers))
         status, response_headers, payload = self.transport(method, url, headers, body, self.timeout)
         if status not in expected:
+            if status == 404:
+                raise CalDAVNotFound(f"{method} {url} returned HTTP {status}")
             if status == 412:
                 raise CalDAVPreconditionFailed(f"{method} {url} failed because the remote resource changed")
             raise CalDAVError(f"{method} {url} returned HTTP {status}")
@@ -189,20 +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]:
-    request = urllib.request.Request(url, data=body, headers=dict(headers), method=method)
+    url = validate_http_url(url)
     try:
-        with urllib.request.urlopen(request, timeout=timeout) as response:
+        url = validate_outbound_http_url(url, label="CalDAV URL")
-            return response.status, dict(response.headers.items()), response.read()
+        request = urllib.request.Request(  # noqa: S310 - URL is validated and origin-confined.
+            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 (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")
@@ -232,8 +420,169 @@ def parse_multistatus(payload: bytes) -> CalDAVReportResult:
     return CalDAVReportResult(objects=objects, sync_token=sync_token, ctag=ctag)
 
 
+def parse_discovery_multistatus(payload: bytes) -> list[_DAVDiscoveryResponse]:
+    try:
+        root = SafeElementTree.fromstring(payload)
+    except SafeElementTree.ParseError as exc:
+        raise CalDAVError(f"Invalid CalDAV XML response: {exc}") from exc
+    return [
+        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:
+        return None
+    draft = _DAVDiscoveryDraft()
+    for propstat in child_elements(response, "propstat"):
+        _apply_discovery_propstat(draft, propstat)
+    return _DAVDiscoveryResponse(
+        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:
+        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)
+    text = item.text.strip() if item.text else ""
+    if name == "displayname" and text:
+        draft.display_name = text or draft.display_name
+    elif name == "calendar-color" and text:
+        draft.color = text or draft.color
+    elif name == "getctag" and text:
+        draft.ctag = text or draft.ctag
+    elif name == "sync-token" and text:
+        draft.sync_token = text or draft.sync_token
+    elif name == "resourcetype":
+        draft.is_calendar = draft.is_calendar or discovery_resource_is_calendar(item)
+    elif name in {"current-user-principal", "principal-URL"}:
+        draft.principal_hrefs.extend(nested_href_texts(item))
+    elif name == "calendar-home-set":
+        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":
+            continue
+        component_name = (component.attrib.get("name") or "").strip().upper()
+        if component_name:
+            names.append(component_name)
+    return names
+
+
+def dedupe_tuple(values: list[str]) -> tuple[str, ...]:
+    return tuple(dict.fromkeys(values))
+
+
 def ensure_collection_url(value: str) -> str:
-    return value if value.endswith("/") else f"{value}/"
+    value = value.strip()
+    if value and "://" not in value and not value.startswith("/"):
+        value = f"https://{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 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:
@@ -253,23 +602,31 @@ 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: Any) -> list[str]:
+    hrefs: list[str] = []
+    for child in element.iter():
+        if local_name(child.tag) == "href" and child.text and child.text.strip():
+            hrefs.append(child.text.strip())
+    return hrefs
+
+
 def local_name(tag: str) -> str:
     return tag.rsplit("}", 1)[-1] if "}" in tag else tag

src/govoplan_calendar/backend/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
@@ -29,7 +29,7 @@ class CalendarCollection(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
     slug: Mapped[str] = mapped_column(String(100), nullable=False)
     name: Mapped[str] = mapped_column(String(255), nullable=False)
     description: Mapped[str | None] = mapped_column(Text)
@@ -39,7 +39,7 @@ class CalendarCollection(Base, TimestampMixin):
     owner_id: Mapped[str | None] = mapped_column(String(36), nullable=True, index=True)
     visibility: Mapped[str] = mapped_column(String(20), default="tenant", nullable=False, index=True)
     is_default: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False, index=True)
-    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
     metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
 
@@ -56,7 +56,7 @@ class CalendarEvent(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
     calendar_id: Mapped[str] = mapped_column(ForeignKey("calendar_collections.id", ondelete="CASCADE"), nullable=False, index=True)
     uid: Mapped[str] = mapped_column(String(255), nullable=False, index=True)
     recurrence_id: Mapped[str | None] = mapped_column(String(255), nullable=True, index=True)
@@ -86,8 +86,8 @@ class CalendarEvent(Base, TimestampMixin):
     etag: Mapped[str | None] = mapped_column(String(255), index=True)
     icalendar: Mapped[dict[str, Any]] = mapped_column(JSON, default=dict, nullable=False)
     raw_ics: Mapped[str | None] = mapped_column(Text)
-    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
-    updated_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    updated_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
     metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
 
@@ -110,7 +110,7 @@ class CalendarSyncSource(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
     calendar_id: Mapped[str] = mapped_column(ForeignKey("calendar_collections.id", ondelete="CASCADE"), nullable=False, index=True)
     source_kind: Mapped[str] = mapped_column(String(30), default="caldav", nullable=False, index=True)
     collection_url: Mapped[str] = mapped_column(String(1000), nullable=False)
@@ -142,13 +142,78 @@ class CalendarSyncCredential(Base, TimestampMixin):
     )
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
-    tenant_id: Mapped[str] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
     credential_kind: Mapped[str] = mapped_column(String(30), nullable=False, index=True)
     label: Mapped[str | None] = mapped_column(String(255))
     secret_encrypted: Mapped[str | None] = mapped_column(Text)
-    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True)
+    created_by_user_id: Mapped[str | None] = mapped_column(ForeignKey("access_users.id", ondelete="SET NULL"), nullable=True, index=True)
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
     metadata_: Mapped[dict[str, Any] | None] = mapped_column("metadata", JSON, nullable=True)
 
 
-__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

@@ -92,6 +92,8 @@ def parse_vevent_component(calendar: Calendar, event: Event, *, raw_ics: str) ->
     properties = component_property_records(event)
     alarms = [component_alarm_record(alarm) for alarm in event.subcomponents if alarm.name == "VALARM"]
     standard = standard_property_index(properties)
+    if dtend is None and duration_seconds is not None:
+        standard["uses_duration"] = True
 
     return {
         "uid": uid,
@@ -151,32 +153,58 @@ 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))
-    if event.end_at is not None:
+    if event_uses_duration(event):
+        component.add("duration", timedelta(seconds=int(event.duration_seconds)))
+    elif event.end_at is not None:
         component.add("dtend", event_temporal_value(event.end_at, all_day=event.all_day, timezone_id=event.timezone))
     elif getattr(event, "duration_seconds", None) is not None:
         component.add("duration", timedelta(seconds=int(event.duration_seconds)))
     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 []:
@@ -186,11 +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.
@@ -474,6 +497,16 @@ def metadata_value(event: Any, key: str) -> str | None:
     return str(value) if value else None
 
 
+def event_uses_duration(event: Any) -> bool:
+    if getattr(event, "duration_seconds", None) is None:
+        return False
+    raw_metadata = getattr(event, "icalendar", None)
+    if not isinstance(raw_metadata, dict):
+        return False
+    standard = raw_metadata.get("standard")
+    return isinstance(standard, dict) and standard.get("uses_duration") is True
+
+
 def event_temporal_value(value: datetime, *, all_day: bool, timezone_id: str | None) -> date | datetime:
     value = normalize_datetime(value)
     if all_day:

src/govoplan_calendar/backend/manifest.py

@@ -1,13 +1,67 @@
 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,
+    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(
@@ -27,11 +81,11 @@ 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 = (
@@ -43,11 +97,11 @@ 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(
@@ -58,20 +112,32 @@ 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(),
     }
 
 
@@ -84,16 +150,46 @@ 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="0.1.5",
+    version="0.1.8",
-    dependencies=("access",),
+    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",
@@ -105,19 +201,14 @@ 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/7c8d9e0f1a2b_calendar_collections_events.py

@@ -1,7 +1,7 @@
 """calendar collections and VEVENT storage
 
 Revision ID: 7c8d9e0f1a2b
-Revises: 1b2c3d4e5f70
+Revises: 2e3f4a5b6c7d
 Create Date: 2026-07-07 00:00:00.000000
 """
 from __future__ import annotations
@@ -11,14 +11,19 @@ import sqlalchemy as sa
 
 
 revision = "7c8d9e0f1a2b"
-down_revision = "1b2c3d4e5f70"
+down_revision = "2e3f4a5b6c7d"
 branch_labels = None
 depends_on = None
 
 
+def _scope_fk_target(tables: set[str]) -> str:
+    return "core_scopes.id" if "core_scopes" in tables else "tenancy_tenants.id"
+
+
 def upgrade() -> None:
     inspector = sa.inspect(op.get_bind())
     tables = set(inspector.get_table_names())
+    scope_fk_target = _scope_fk_target(tables)
     if "calendar_collections" not in tables:
         op.create_table(
             "calendar_collections",
@@ -38,8 +43,8 @@ def upgrade() -> None:
             sa.Column("metadata", sa.JSON(), nullable=True),
             sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
             sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
-            sa.ForeignKeyConstraint(["created_by_user_id"], ["users.id"], name=op.f("fk_calendar_collections_created_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["created_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_collections_created_by_user_id_users"), ondelete="SET NULL"),
-            sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_collections_tenant_id_tenants"), ondelete="CASCADE"),
+            sa.ForeignKeyConstraint(["tenant_id"], [scope_fk_target], 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_tenant_id"), "calendar_collections", ["tenant_id"], unique=False)
@@ -100,9 +105,9 @@ def upgrade() -> None:
             sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
             sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
             sa.ForeignKeyConstraint(["calendar_id"], ["calendar_collections.id"], name=op.f("fk_calendar_events_calendar_id_calendar_collections"), ondelete="CASCADE"),
-            sa.ForeignKeyConstraint(["created_by_user_id"], ["users.id"], name=op.f("fk_calendar_events_created_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["created_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_events_created_by_user_id_users"), ondelete="SET NULL"),
-            sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_events_tenant_id_tenants"), ondelete="CASCADE"),
+            sa.ForeignKeyConstraint(["tenant_id"], [scope_fk_target], name=op.f("fk_calendar_events_tenant_id_scopes"), ondelete="CASCADE"),
-            sa.ForeignKeyConstraint(["updated_by_user_id"], ["users.id"], name=op.f("fk_calendar_events_updated_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["updated_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_events_updated_by_user_id_users"), ondelete="SET NULL"),
             sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_events")),
             sa.UniqueConstraint("calendar_id", "uid", "recurrence_id", name="uq_calendar_events_calendar_uid_recurrence"),
         )

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

@@ -16,11 +16,16 @@ branch_labels = None
 depends_on = None
 
 
+def _scope_fk_target(tables: set[str]) -> str:
+    return "core_scopes.id" if "core_scopes" in tables else "tenancy_tenants.id"
+
+
 def upgrade() -> None:
     inspector = sa.inspect(op.get_bind())
     tables = set(inspector.get_table_names())
     if "calendar_sync_sources" in tables:
         return
+    scope_fk_target = _scope_fk_target(tables)
     op.create_table(
         "calendar_sync_sources",
         sa.Column("id", sa.String(length=36), nullable=False),
@@ -42,7 +47,7 @@ def upgrade() -> None:
         sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
         sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
         sa.ForeignKeyConstraint(["calendar_id"], ["calendar_collections.id"], name=op.f("fk_calendar_sync_sources_calendar_id_calendar_collections"), ondelete="CASCADE"),
-        sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_sync_sources_tenant_id_tenants"), ondelete="CASCADE"),
+        sa.ForeignKeyConstraint(["tenant_id"], [scope_fk_target], name=op.f("fk_calendar_sync_sources_tenant_id_scopes"), ondelete="CASCADE"),
         sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_sync_sources")),
     )
     for column in ("tenant_id", "calendar_id", "source_kind", "deleted_at"):

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

@@ -16,10 +16,15 @@ branch_labels = None
 depends_on = None
 
 
+def _scope_fk_target(tables: set[str]) -> str:
+    return "core_scopes.id" if "core_scopes" in tables else "tenancy_tenants.id"
+
+
 def upgrade() -> None:
     bind = op.get_bind()
     inspector = sa.inspect(bind)
     tables = set(inspector.get_table_names())
+    scope_fk_target = _scope_fk_target(tables)
     if "calendar_sync_sources" in tables:
         columns = {column["name"] for column in inspector.get_columns("calendar_sync_sources")}
         add_column_if_missing(columns, "sync_enabled", sa.Column("sync_enabled", sa.Boolean(), server_default=sa.true(), nullable=False))
@@ -47,8 +52,8 @@ def upgrade() -> None:
             sa.Column("metadata", sa.JSON(), nullable=True),
             sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
             sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
-            sa.ForeignKeyConstraint(["created_by_user_id"], ["users.id"], name=op.f("fk_calendar_sync_credentials_created_by_user_id_users"), ondelete="SET NULL"),
+            sa.ForeignKeyConstraint(["created_by_user_id"], ["access_users.id"], name=op.f("fk_calendar_sync_credentials_created_by_user_id_users"), ondelete="SET NULL"),
-            sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], name=op.f("fk_calendar_sync_credentials_tenant_id_tenants"), ondelete="CASCADE"),
+            sa.ForeignKeyConstraint(["tenant_id"], [scope_fk_target], name=op.f("fk_calendar_sync_credentials_tenant_id_scopes"), ondelete="CASCADE"),
             sa.PrimaryKeyConstraint("id", name=op.f("pk_calendar_sync_credentials")),
         )
         for column in ("tenant_id", "credential_kind", "created_by_user_id", "deleted_at"):

src/govoplan_calendar/backend/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

@@ -5,10 +5,16 @@ from datetime import datetime
 from fastapi import APIRouter, Body, Depends, HTTPException, Query, Response, status
 from sqlalchemy.orm import Session
 
-from govoplan_access.backend.auth.dependencies import ApiPrincipal, get_api_principal, has_scope
+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
 from govoplan_calendar.backend.caldav import CalDAVError
 from govoplan_calendar.backend.schemas import (
+    CalendarCalDavDiscoveryRequest,
+    CalendarCalDavDiscoveryResponse,
     CalendarCalDavDueSyncItemResponse,
     CalendarCalDavDueSyncResponse,
     CalendarCalDavSourceCreateRequest,
@@ -23,36 +29,66 @@ from govoplan_calendar.backend.schemas import (
     CalendarCollectionResponse,
     CalendarCollectionUpdateRequest,
     CalendarEventCreateRequest,
+    CalendarEventDeltaResponse,
     CalendarEventListResponse,
     CalendarEventResponse,
     CalendarEventUpdateRequest,
     CalendarFreeBusyRequest,
     CalendarFreeBusyResponse,
     CalendarIcsImportRequest,
+    CalendarOutboxDispatchResponse,
+    CalendarOutboxOperationListResponse,
+    CalendarOutboxOperationResponse,
+    CalendarSyncDueSyncItemResponse,
+    CalendarSyncDueSyncResponse,
+    CalendarSyncSourceCreateRequest,
+    CalendarSyncSourceListResponse,
+    CalendarSyncSourceResponse,
+    CalendarSyncSourceSyncRequest,
+    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,
     caldav_source_response,
     caldav_sync_response,
     calendar_response,
     create_calendar,
     create_caldav_source,
+    create_sync_source,
     create_event,
     delete_calendar,
     delete_caldav_source,
+    delete_sync_source,
     delete_event,
+    discover_caldav_calendars,
     event_response,
-    get_caldav_source,
     get_event,
     import_ics_event,
     list_freebusy,
     list_caldav_sources,
     list_calendars,
     list_events,
+    list_sync_sources,
+    normalize_datetime,
+    sync_due_sources,
     sync_due_caldav_sources,
     sync_caldav_source,
+    sync_source,
     update_calendar,
     update_caldav_source,
+    update_sync_source,
     update_event,
 )
 from govoplan_core.db.session import get_session
@@ -78,17 +114,142 @@ def _event_response(event) -> CalendarEventResponse:
     return CalendarEventResponse.model_validate(event_response(event))
 
 
+def _calendar_event_watermark(session: Session, tenant_id: str) -> str:
+    return encode_sequence_watermark(
+        max_sequence_id(session, tenant_id=tenant_id, module_id=CALENDAR_MODULE_ID, collections=(CALENDAR_EVENTS_COLLECTION,))
+    )
+
+
+def _parse_payload_datetime(value) -> datetime | None:
+    if not isinstance(value, str) or not value:
+        return None
+    try:
+        return datetime.fromisoformat(value)
+    except ValueError:
+        return None
+
+
+def _event_interval_overlaps(payload: dict, *, prefix: str, start_at: datetime | None, end_at: datetime | None) -> bool:
+    event_start = _parse_payload_datetime(payload.get(f"{prefix}start_at"))
+    event_end = _parse_payload_datetime(payload.get(f"{prefix}end_at")) or event_start
+    if event_start is None:
+        return False
+    if start_at is not None and event_end is not None and event_end < normalize_datetime(start_at):
+        return False
+    if end_at is not None and event_start > normalize_datetime(end_at):
+        return False
+    return True
+
+
+def _event_payload_matches_window(entry, *, calendar_id: str | None, start_at: datetime | None, end_at: datetime | None) -> bool:
+    payload = entry.payload or {}
+    current_calendar = payload.get("calendar_id")
+    previous_calendar = payload.get("previous_calendar_id")
+    current_calendar_matches = calendar_id is None or current_calendar == calendar_id
+    previous_calendar_matches = calendar_id is None or previous_calendar == calendar_id
+    return (
+        current_calendar_matches and _event_interval_overlaps(payload, prefix="", start_at=start_at, end_at=end_at)
+    ) or (
+        previous_calendar_matches and _event_interval_overlaps(payload, prefix="previous_", start_at=start_at, end_at=end_at)
+    )
+
+
+def _visible_events_for_delta(
+    session: Session,
+    *,
+    tenant_id: str,
+    event_ids: list[str],
+    calendar_id: str | None,
+    start_at: datetime | None,
+    end_at: datetime | None,
+) -> list[CalendarEvent]:
+    if not event_ids:
+        return []
+    query = session.query(CalendarEvent).filter(
+        CalendarEvent.tenant_id == tenant_id,
+        CalendarEvent.id.in_(event_ids),
+        CalendarEvent.deleted_at.is_(None),
+    )
+    if calendar_id:
+        query = query.filter(CalendarEvent.calendar_id == calendar_id)
+    if start_at is not None:
+        normalized_start = normalize_datetime(start_at)
+        query = query.filter((CalendarEvent.end_at.is_(None)) | (CalendarEvent.end_at >= normalized_start))
+    if end_at is not None:
+        query = query.filter(CalendarEvent.start_at <= normalize_datetime(end_at))
+    return query.order_by(CalendarEvent.start_at.asc(), CalendarEvent.summary.asc(), CalendarEvent.id.asc()).all()
+
+
+def _full_event_delta_response(
+    session: Session,
+    *,
+    tenant_id: str,
+    calendar_id: str | None,
+    start_at: datetime | None,
+    end_at: datetime | None,
+) -> CalendarEventDeltaResponse:
+    events = list_events(session, tenant_id=tenant_id, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    return CalendarEventDeltaResponse(
+        events=[_event_response(event) for event in events],
+        deleted=[],
+        watermark=_calendar_event_watermark(session, tenant_id),
+        has_more=False,
+        full=True,
+    )
+
+
+def _event_delta_entries(session: Session, *, tenant_id: str, since: str, limit: int):
+    try:
+        since_sequence = decode_sequence_watermark(since)
+    except ValueError as exc:
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(exc)) from exc
+    if sequence_watermark_is_expired(
+        session,
+        since=since_sequence,
+        tenant_id=tenant_id,
+        module_id=CALENDAR_MODULE_ID,
+        collections=(CALENDAR_EVENTS_COLLECTION,),
+    ):
+        return None, False
+    entries_plus_one = sequence_entries_since(
+        session,
+        since=since_sequence,
+        tenant_id=tenant_id,
+        module_id=CALENDAR_MODULE_ID,
+        collections=(CALENDAR_EVENTS_COLLECTION,),
+        limit=limit + 1,
+    )
+    has_more = len(entries_plus_one) > limit
+    return entries_plus_one[:limit], has_more
+
+
 def _caldav_source_response(source) -> CalendarCalDavSourceResponse:
     return CalendarCalDavSourceResponse.model_validate(caldav_source_response(source))
 
 
+def _sync_source_response(source) -> CalendarSyncSourceResponse:
+    return CalendarSyncSourceResponse.model_validate(caldav_source_response(source))
+
+
+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])
 
@@ -107,7 +268,7 @@ def api_create_calendar(
         return _calendar_response(calendar)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.patch("/calendars/{calendar_id}", response_model=CalendarCollectionResponse)
@@ -137,12 +298,154 @@ 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:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.get("/sync-sources", response_model=CalendarSyncSourceListResponse)
+def api_list_sync_sources(
+    calendar_id: str | None = None,
+    source_kind: str | None = None,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:read")
+    sources = list_sync_sources(session, tenant_id=principal.tenant_id, calendar_id=calendar_id, source_kind=source_kind)
+    return CalendarSyncSourceListResponse(sources=[_sync_source_response(source) for source in sources])
+
+
+@router.post("/sync-sources", response_model=CalendarSyncSourceResponse, status_code=status.HTTP_201_CREATED)
+def api_create_sync_source(
+    payload: CalendarSyncSourceCreateRequest,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        source = create_sync_source(session, tenant_id=principal.tenant_id, user_id=principal.user.id, payload=payload)
+        session.commit()
+        session.refresh(source)
+        return _sync_source_response(source)
+    except CalendarError as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.patch("/sync-sources/{source_id}", response_model=CalendarSyncSourceResponse)
+def api_update_sync_source(
+    source_id: str,
+    payload: CalendarSyncSourceUpdateRequest,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        source = update_sync_source(
+            session,
+            tenant_id=principal.tenant_id,
+            source_id=source_id,
+            payload=payload,
+            user_id=principal.user.id,
+            api_key_id=principal.api_key_id,
+        )
+        session.commit()
+        session.refresh(source)
+        return _sync_source_response(source)
+    except CalendarError as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.delete("/sync-sources/{source_id}", status_code=status.HTTP_204_NO_CONTENT)
+def api_delete_sync_source(
+    source_id: str,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        delete_sync_source(
+            session,
+            tenant_id=principal.tenant_id,
+            source_id=source_id,
+            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()
+        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)
+def api_sync_source(
+    source_id: str,
+    payload: CalendarSyncSourceSyncRequest | None = None,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:event:import")
+    payload = payload or CalendarSyncSourceSyncRequest()
+    try:
+        source, stats = sync_source(
+            session,
+            tenant_id=principal.tenant_id,
+            user_id=principal.user.id,
+            source_id=source_id,
+            password=payload.password,
+            bearer_token=payload.bearer_token,
+            force_full=payload.force_full,
+        )
+        session.commit()
+        session.refresh(source)
+        return CalendarSyncSourceSyncResponse.model_validate(caldav_sync_response(source, stats))
+    except (CalendarError, CalDAVError, ICalendarError) as exc:
+        session.rollback()
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
+@router.post("/sync-sources/sync-due", response_model=CalendarSyncDueSyncResponse)
+def api_sync_due_sources(
+    limit: int = Query(default=50, ge=1, le=200),
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:event:import")
+    results = sync_due_sources(session, tenant_id=principal.tenant_id, user_id=principal.user.id, limit=limit)
+    session.commit()
+    return CalendarSyncDueSyncResponse(
+        results=[
+            CalendarSyncDueSyncItemResponse(
+                source_id=item.source_id,
+                calendar_id=item.calendar_id,
+                status=item.status,
+                error=item.error,
+                created=item.stats.created if item.stats else 0,
+                updated=item.stats.updated if item.stats else 0,
+                deleted=item.stats.deleted if item.stats else 0,
+                unchanged=item.stats.unchanged if item.stats else 0,
+                fetched=item.stats.fetched if item.stats else 0,
+            )
+            for item in results
+        ]
+    )
 
 
 @router.get("/caldav/sources", response_model=CalendarCalDavSourceListResponse)
@@ -156,6 +459,20 @@ def api_list_caldav_sources(
     return CalendarCalDavSourceListResponse(sources=[_caldav_source_response(source) for source in sources])
 
 
+@router.post("/caldav/discover", response_model=CalendarCalDavDiscoveryResponse)
+def api_discover_caldav_calendars(
+    payload: CalendarCalDavDiscoveryRequest,
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:calendar:admin")
+    try:
+        calendars = discover_caldav_calendars(session, tenant_id=principal.tenant_id, payload=payload)
+        return CalendarCalDavDiscoveryResponse(calendars=calendars)
+    except (CalendarError, CalDAVError) as exc:
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
+
+
 @router.post("/caldav/sources", response_model=CalendarCalDavSourceResponse, status_code=status.HTTP_201_CREATED)
 def api_create_caldav_source(
     payload: CalendarCalDavSourceCreateRequest,
@@ -170,7 +487,7 @@ def api_create_caldav_source(
         return _caldav_source_response(source)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.patch("/caldav/sources/{source_id}", response_model=CalendarCalDavSourceResponse)
@@ -182,13 +499,20 @@ 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)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.delete("/caldav/sources/{source_id}", status_code=status.HTTP_204_NO_CONTENT)
@@ -199,12 +523,23 @@ 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)
@@ -231,7 +566,7 @@ def api_sync_caldav_source(
         return CalendarCalDavSyncResponse.model_validate(caldav_sync_response(source, stats))
     except (CalendarError, CalDAVError, ICalendarError) as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.post("/caldav/sync-due", response_model=CalendarCalDavDueSyncResponse)
@@ -261,6 +596,117 @@ 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,
@@ -274,13 +720,64 @@ def api_list_events(
     return CalendarEventListResponse(events=[_event_response(event) for event in events])
 
 
+@router.get("/events/delta", response_model=CalendarEventDeltaResponse)
+def api_list_events_delta(
+    calendar_id: str | None = None,
+    start_at: datetime | None = Query(default=None),
+    end_at: datetime | None = Query(default=None),
+    since: str | None = None,
+    limit: int = Query(default=500, ge=1, le=1000),
+    principal: ApiPrincipal = Depends(get_api_principal),
+    session: Session = Depends(get_session),
+):
+    _require_scope(principal, "calendar:event:read")
+    if since is None:
+        return _full_event_delta_response(session, tenant_id=principal.tenant_id, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    entries, has_more = _event_delta_entries(session, tenant_id=principal.tenant_id, since=since, limit=limit)
+    if entries is None:
+        return _full_event_delta_response(session, tenant_id=principal.tenant_id, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    scoped_entries = [
+        entry
+        for entry in entries
+        if entry.resource_type == CALENDAR_EVENT_RESOURCE and _event_payload_matches_window(entry, calendar_id=calendar_id, start_at=start_at, end_at=end_at)
+    ]
+    changed_ids = list(dict.fromkeys(entry.resource_id for entry in scoped_entries if entry.operation != "deleted"))
+    visible_events = _visible_events_for_delta(
+        session,
+        tenant_id=principal.tenant_id,
+        event_ids=changed_ids,
+        calendar_id=calendar_id,
+        start_at=start_at,
+        end_at=end_at,
+    )
+    visible_ids = {event.id for event in visible_events}
+    deleted = [
+        DeltaDeletedItem(
+            id=entry.resource_id,
+            resource_type=entry.resource_type,
+            revision=encode_sequence_watermark(entry.id),
+            deleted_at=entry.created_at if entry.operation == "deleted" else None,
+        )
+        for entry in scoped_entries
+        if entry.resource_id not in visible_ids
+    ]
+    watermark = encode_sequence_watermark(entries[-1].id) if has_more and entries else _calendar_event_watermark(session, principal.tenant_id)
+    return CalendarEventDeltaResponse(
+        events=[_event_response(event) for event in visible_events],
+        deleted=deleted,
+        watermark=watermark,
+        has_more=has_more,
+        full=False,
+    )
+
+
 @router.post("/events", response_model=CalendarEventResponse, status_code=status.HTTP_201_CREATED)
 def api_create_event(
     payload: CalendarEventCreateRequest,
     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()
@@ -288,7 +785,7 @@ def api_create_event(
         return _event_response(event)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.get("/events/{event_id}", response_model=CalendarEventResponse)
@@ -311,7 +808,7 @@ 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()
@@ -319,7 +816,7 @@ def api_update_event(
         return _event_response(event)
     except CalendarError as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.delete("/events/{event_id}", status_code=status.HTTP_204_NO_CONTENT)
@@ -328,9 +825,9 @@ 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)
+        delete_event(session, tenant_id=principal.tenant_id, event_id=event_id, user_id=principal.user.id)
         session.commit()
         return Response(status_code=status.HTTP_204_NO_CONTENT)
     except CalendarError as exc:
@@ -362,7 +859,7 @@ def api_import_ics_event(
         return _event_response(event)
     except (CalendarError, ICalendarError) as exc:
         session.rollback()
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc
 
 
 @router.get("/events/{event_id}/ics")
@@ -393,7 +890,7 @@ 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,
@@ -404,4 +901,4 @@ def api_freebusy(
         )
         return CalendarFreeBusyResponse(start_at=payload.start_at, end_at=payload.end_at, busy=busy)
     except CalendarError as exc:
-        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc)) from exc
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_CONTENT, detail=str(exc)) from exc

src/govoplan_calendar/backend/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

@@ -5,12 +5,20 @@ from typing import Any, Literal
 
 from pydantic import BaseModel, ConfigDict, Field, SecretStr
 
+from govoplan_core.api.v1.schemas import DeltaDeletedItem
+
 
 CalendarOwnerType = Literal["tenant", "user", "group", "resource"]
 CalendarVisibility = Literal["private", "tenant", "shared", "public"]
 CalendarDeleteEventAction = Literal["delete", "move"]
+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"]
 CalendarCalDavConflictPolicy = Literal["etag", "overwrite"]
 
 
@@ -47,6 +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):
@@ -70,9 +79,10 @@ class CalendarCollectionListResponse(BaseModel):
     calendars: list[CalendarCollectionResponse] = Field(default_factory=list)
 
 
-class CalendarCalDavSourceCreateRequest(BaseModel):
+class CalendarSyncSourceCreateRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 
+    source_kind: CalendarSyncSourceKind = "caldav"
     calendar_id: str
     collection_url: str = Field(min_length=1, max_length=1000)
     display_name: str | None = Field(default=None, max_length=255)
@@ -88,7 +98,11 @@ class CalendarCalDavSourceCreateRequest(BaseModel):
     metadata: dict[str, Any] = Field(default_factory=dict)
 
 
-class CalendarCalDavSourceUpdateRequest(BaseModel):
+class CalendarCalDavSourceCreateRequest(CalendarSyncSourceCreateRequest):
+    source_kind: Literal["caldav"] = "caldav"
+
+
+class CalendarSyncSourceUpdateRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 
     calendar_id: str | None = None
@@ -108,7 +122,11 @@ class CalendarCalDavSourceUpdateRequest(BaseModel):
     metadata: dict[str, Any] | None = None
 
 
-class CalendarCalDavSourceResponse(BaseModel):
+class CalendarCalDavSourceUpdateRequest(CalendarSyncSourceUpdateRequest):
+    pass
+
+
+class CalendarSyncSourceResponse(BaseModel):
     id: str
     tenant_id: str
     calendar_id: str
@@ -135,11 +153,44 @@ class CalendarCalDavSourceResponse(BaseModel):
     metadata: dict[str, Any] = Field(default_factory=dict)
 
 
+class CalendarCalDavSourceResponse(CalendarSyncSourceResponse):
+    pass
+
+
+class CalendarSyncSourceListResponse(BaseModel):
+    sources: list[CalendarSyncSourceResponse] = Field(default_factory=list)
+
+
 class CalendarCalDavSourceListResponse(BaseModel):
     sources: list[CalendarCalDavSourceResponse] = Field(default_factory=list)
 
 
-class CalendarCalDavSyncRequest(BaseModel):
+class CalendarCalDavDiscoveryRequest(BaseModel):
+    model_config = ConfigDict(extra="forbid")
+
+    url: str = Field(min_length=1, max_length=1000)
+    source_id: str | None = None
+    auth_type: CalendarSyncAuthType | None = None
+    username: str | None = Field(default=None, max_length=255)
+    credential_ref: str | None = Field(default=None, max_length=255)
+    password: SecretStr | None = None
+    bearer_token: SecretStr | None = None
+
+
+class CalendarCalDavDiscoveryCalendarResponse(BaseModel):
+    collection_url: str
+    href: str
+    display_name: str | None = None
+    color: str | None = None
+    ctag: str | None = None
+    sync_token: str | None = None
+
+
+class CalendarCalDavDiscoveryResponse(BaseModel):
+    calendars: list[CalendarCalDavDiscoveryCalendarResponse] = Field(default_factory=list)
+
+
+class CalendarSyncSourceSyncRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 
     password: str | None = None
@@ -147,8 +198,12 @@ class CalendarCalDavSyncRequest(BaseModel):
     force_full: bool = False
 
 
-class CalendarCalDavSyncResponse(BaseModel):
+class CalendarCalDavSyncRequest(CalendarSyncSourceSyncRequest):
-    source: CalendarCalDavSourceResponse
+    pass
+
+
+class CalendarSyncSourceSyncResponse(BaseModel):
+    source: CalendarSyncSourceResponse
     created: int = 0
     updated: int = 0
     deleted: int = 0
@@ -161,7 +216,11 @@ class CalendarCalDavSyncResponse(BaseModel):
     errors: list[str] = Field(default_factory=list)
 
 
-class CalendarCalDavDueSyncItemResponse(BaseModel):
+class CalendarCalDavSyncResponse(CalendarSyncSourceSyncResponse):
+    source: CalendarCalDavSourceResponse
+
+
+class CalendarSyncDueSyncItemResponse(BaseModel):
     source_id: str
     calendar_id: str
     status: str
@@ -173,10 +232,62 @@ class CalendarCalDavDueSyncItemResponse(BaseModel):
     fetched: int = 0
 
 
+class CalendarCalDavDueSyncItemResponse(CalendarSyncDueSyncItemResponse):
+    pass
+
+
+class CalendarSyncDueSyncResponse(BaseModel):
+    results: list[CalendarSyncDueSyncItemResponse] = Field(default_factory=list)
+
+
 class CalendarCalDavDueSyncResponse(BaseModel):
     results: list[CalendarCalDavDueSyncItemResponse] = Field(default_factory=list)
 
 
+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")
 
@@ -283,6 +394,14 @@ class CalendarEventListResponse(BaseModel):
     events: list[CalendarEventResponse] = Field(default_factory=list)
 
 
+class CalendarEventDeltaResponse(BaseModel):
+    events: list[CalendarEventResponse] = Field(default_factory=list)
+    deleted: list[DeltaDeletedItem] = Field(default_factory=list)
+    watermark: str | None = None
+    has_more: bool = False
+    full: bool = False
+
+
 class CalendarFreeBusyRequest(BaseModel):
     model_config = ConfigDict(extra="forbid")
 

src/govoplan_calendar/backend/tasks.py

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

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_ical.py

@@ -92,6 +92,7 @@ END:VCALENDAR
         self.assertEqual(event["start_at"], datetime(2026, 7, 8, 7, 0, tzinfo=timezone.utc))
         self.assertEqual(event["end_at"], datetime(2026, 7, 8, 8, 30, tzinfo=timezone.utc))
         self.assertEqual(event["duration_seconds"], 5400)
+        self.assertTrue(event["icalendar"]["standard"]["uses_duration"])
         self.assertEqual(event["description"], "Line one\nLine two")
         self.assertEqual(event["location"], "Room; 1")
         self.assertEqual(event["timezone"], "Europe/Berlin")
@@ -164,6 +165,38 @@ END:VCALENDAR
         self.assertIn("BEGIN:VALARM", ics)
         self.assertIn("TRIGGER:-PT15M", ics)
 
+    def test_generated_ics_preserves_duration_when_source_used_duration(self) -> None:
+        event = SimpleNamespace(
+            uid="event-duration@example.test",
+            start_at=datetime(2026, 7, 8, 7, 0, tzinfo=timezone.utc),
+            end_at=datetime(2026, 7, 8, 8, 30, tzinfo=timezone.utc),
+            duration_seconds=5400,
+            all_day=False,
+            timezone="Europe/Berlin",
+            summary="Duration",
+            sequence=0,
+            status="CONFIRMED",
+            transparency="OPAQUE",
+            classification="PUBLIC",
+            description=None,
+            location=None,
+            categories=[],
+            rrule=None,
+            organizer=None,
+            attendees=[],
+            rdate=[],
+            exdate=[],
+            reminders=[],
+            attachments=[],
+            related_to=[],
+            icalendar={"standard": {"uses_duration": True}},
+        )
+
+        ics = event_to_ics(event)
+
+        self.assertIn("DURATION:PT1H30M", ics)
+        self.assertNotIn("DTEND", ics)
+
     def test_expand_event_occurrences_applies_rrule_rdate_and_exdate(self) -> None:
         parsed = parse_vevent(
             """BEGIN:VCALENDAR

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

@@ -0,0 +1,348 @@
+from __future__ import annotations
+
+import json
+import unittest
+from datetime import datetime, timezone
+from unittest.mock import patch
+
+from sqlalchemy import create_engine
+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, 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
+
+
+class CalendarSyncSourceTests(unittest.TestCase):
+    def setUp(self) -> None:
+        self.engine = create_engine("sqlite:///:memory:")
+        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()
+        return session, calendar
+
+    def test_ics_subscription_sync_imports_events_and_blocks_local_mutation(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",
+                sync_direction="two_way",
+            ),
+        )
+
+        ics = """BEGIN:VCALENDAR
+VERSION:2.0
+BEGIN:VEVENT
+UID:ics-1@example.test
+DTSTART:20260708T090000Z
+DTEND:20260708T100000Z
+SUMMARY:ICS item
+END:VEVENT
+END:VCALENDAR
+"""
+        with patch("govoplan_calendar.backend.service.http_request", return_value=(200, {"etag": '"feed-1"'}, ics)):
+            refreshed, stats = sync_source(session, tenant_id="tenant-1", user_id=None, source_id=source.id)
+
+        event = session.query(CalendarEvent).one()
+        self.assertEqual(refreshed.sync_direction, "inbound")
+        self.assertEqual(stats.created, 1)
+        self.assertEqual(event.source_kind, "ics")
+        self.assertEqual(event.summary, "ICS item")
+        with self.assertRaisesRegex(CalendarError, "inbound-only"):
+            create_event(
+                session,
+                tenant_id="tenant-1",
+                user_id=None,
+                payload=CalendarEventCreateRequest(
+                    calendar_id=calendar.id,
+                    summary="Local edit",
+                    start_at=datetime(2026, 7, 8, 12, tzinfo=timezone.utc),
+                ),
+            )
+
+    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(
+            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": [
+                {
+                    "id": "graph-event-1",
+                    "iCalUId": "graph-uid-1",
+                    "subject": "Graph item",
+                    "start": {"dateTime": "2026-07-08T09:00:00", "timeZone": "UTC"},
+                    "end": {"dateTime": "2026-07-08T10:00:00", "timeZone": "UTC"},
+                    "@odata.etag": "graph-etag-1",
+                }
+            ],
+            "@odata.deltaLink": "https://graph.microsoft.com/v1.0/me/calendar/events/delta?$deltatoken=next",
+        }
+
+        with patch("govoplan_calendar.backend.service.http_request", return_value=(200, {}, json.dumps(payload))) as request:
+            refreshed, stats = sync_source(session, tenant_id="tenant-1", user_id=None, source_id=source.id)
+
+        event = session.query(CalendarEvent).one()
+        self.assertEqual(stats.created, 1)
+        self.assertEqual(refreshed.sync_token, payload["@odata.deltaLink"])
+        self.assertEqual(event.source_kind, "graph")
+        self.assertEqual(event.source_href, "graph-event-1")
+        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(
+            session,
+            tenant_id="tenant-1",
+            user_id=None,
+            payload=CalendarSyncSourceCreateRequest(
+                source_kind="ews",
+                calendar_id=calendar.id,
+                collection_url="https://exchange.example.test/EWS/Exchange.asmx",
+                auth_type="basic",
+                username="ada",
+                password="secret",
+            ),
+        )
+        response_xml = """<?xml version="1.0" encoding="utf-8"?>
+<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"
+  xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages"
+  xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
+  <s:Body>
+    <m:FindItemResponse>
+      <m:ResponseMessages>
+        <m:FindItemResponseMessage ResponseClass="Success">
+          <m:RootFolder>
+            <t:Items>
+              <t:CalendarItem>
+                <t:ItemId Id="ews-event-1" ChangeKey="ews-etag-1" />
+                <t:Subject>EWS item</t:Subject>
+                <t:Start>2026-07-08T09:00:00Z</t:Start>
+                <t:End>2026-07-08T10:00:00Z</t:End>
+                <t:IsAllDayEvent>false</t:IsAllDayEvent>
+                <t:UID>ews-uid-1</t:UID>
+              </t:CalendarItem>
+            </t:Items>
+          </m:RootFolder>
+        </m:FindItemResponseMessage>
+      </m:ResponseMessages>
+    </m:FindItemResponse>
+  </s:Body>
+</s:Envelope>"""
+
+        with patch("govoplan_calendar.backend.service.http_request", return_value=(200, {}, response_xml)) as request:
+            _refreshed, stats = sync_source(session, tenant_id="tenant-1", user_id=None, source_id=source.id)
+
+        event = session.query(CalendarEvent).one()
+        self.assertEqual(stats.created, 1)
+        self.assertEqual(event.source_kind, "ews")
+        self.assertEqual(event.source_href, "ews-event-1")
+        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": "0.1.5",
+  "version": "0.1.8",
   "private": true,
   "type": "module",
   "main": "src/index.ts",
@@ -13,9 +13,12 @@
     },
     "./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": "^0.1.5",
+    "@govoplan/core-webui": "^0.1.9",
-    "lucide-react": "^0.555.0",
+    "lucide-react": "^1.23.0",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
     "react-router-dom": "^7.1.1",

webui/src/api/calendar.ts

@@ -55,6 +55,114 @@ export type CalendarEvent = {
 
 export type CalendarCollectionListResponse = { calendars: CalendarCollection[] };
 export type CalendarEventListResponse = { events: CalendarEvent[] };
+export type CalendarDeltaDeletedItem = { id: string; resource_type?: string | null; revision?: string | null; deleted_at?: string | null };
+export type CalendarEventDeltaResponse = {
+  events: CalendarEvent[];
+  deleted: CalendarDeltaDeletedItem[];
+  watermark?: string | null;
+  has_more: boolean;
+  full: boolean;
+};
+
+export type CalendarCalDavAuthType = "none" | "basic" | "bearer";
+export type CalendarCalDavSyncDirection = "inbound" | "two_way";
+export type CalendarCalDavConflictPolicy = "etag" | "overwrite";
+export type CalendarSyncSourceKind = "caldav" | "ics" | "webcal" | "graph" | "ews";
+
+export type CalendarSyncSource = {
+  id: string;
+  tenant_id: string;
+  calendar_id: string;
+  source_kind: CalendarSyncSourceKind;
+  collection_url: string;
+  display_name?: string | null;
+  auth_type: CalendarCalDavAuthType;
+  username?: string | null;
+  has_credential: boolean;
+  sync_enabled: boolean;
+  sync_interval_seconds: number;
+  sync_direction: CalendarCalDavSyncDirection;
+  conflict_policy: CalendarCalDavConflictPolicy;
+  sync_token?: string | null;
+  ctag?: string | null;
+  last_attempt_at?: string | null;
+  last_synced_at?: string | null;
+  next_sync_at?: string | null;
+  last_status?: string | null;
+  last_error?: string | null;
+  created_at: string;
+  updated_at: string;
+  metadata?: Record<string, unknown> | null;
+};
+
+export type CalendarCalDavSource = CalendarSyncSource;
+export type CalendarSyncSourceListResponse = { sources: CalendarSyncSource[] };
+export type CalendarCalDavSourceListResponse = { sources: CalendarCalDavSource[] };
+
+export type CalendarCalDavDiscoveryCandidate = {
+  collection_url: string;
+  href: string;
+  display_name?: string | null;
+  color?: string | null;
+  ctag?: string | null;
+  sync_token?: string | null;
+};
+
+export type CalendarCalDavDiscoveryPayload = {
+  url: string;
+  source_id?: string | null;
+  auth_type?: CalendarCalDavAuthType | null;
+  username?: string | null;
+  password?: string | null;
+  bearer_token?: string | null;
+};
+
+export type CalendarCalDavDiscoveryResponse = { calendars: CalendarCalDavDiscoveryCandidate[] };
+
+export type CalendarSyncSourceCreatePayload = {
+  source_kind?: CalendarSyncSourceKind;
+  calendar_id: string;
+  collection_url: string;
+  display_name?: string | null;
+  auth_type?: CalendarCalDavAuthType;
+  username?: string | null;
+  password?: string | null;
+  bearer_token?: string | null;
+  sync_enabled?: boolean;
+  sync_interval_seconds?: number;
+  sync_direction?: CalendarCalDavSyncDirection;
+  conflict_policy?: CalendarCalDavConflictPolicy;
+  metadata?: Record<string, unknown>;
+};
+
+export type CalendarCalDavSourceCreatePayload = CalendarSyncSourceCreatePayload;
+
+export type CalendarCalDavSourceUpdatePayload = Partial<CalendarCalDavSourceCreatePayload>;
+export type CalendarSyncSourceUpdatePayload = Partial<CalendarSyncSourceCreatePayload>;
+
+export type CalendarSyncSourceSyncPayload = {
+  password?: string | null;
+  bearer_token?: string | null;
+  force_full?: boolean;
+};
+
+export type CalendarCalDavSyncPayload = CalendarSyncSourceSyncPayload;
+
+export type CalendarSyncSourceSyncResponse = {
+  source: CalendarSyncSource;
+  created: number;
+  updated: number;
+  deleted: number;
+  unchanged: number;
+  fetched: number;
+  full_sync: boolean;
+  used_sync_token: boolean;
+  sync_token?: string | null;
+  ctag?: string | null;
+  errors: string[];
+};
+
+export type CalendarCalDavSyncResponse = CalendarSyncSourceSyncResponse;
 
 export type CalendarCollectionCreatePayload = {
   name: string;
@@ -71,25 +179,44 @@ 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 = {
   calendar_id?: string | null;
+  uid?: string | null;
+  recurrence_id?: string | null;
+  sequence?: number;
   summary: string;
   description?: string | null;
   location?: string | null;
-  start_at: string;
-  end_at?: string | null;
-  all_day?: boolean;
-  timezone?: string | null;
   status?: string;
   transparency?: string;
   classification?: string;
+  start_at: string;
+  end_at?: string | null;
+  duration_seconds?: number | null;
+  all_day?: boolean;
+  timezone?: string | null;
+  organizer?: Record<string, unknown> | null;
+  attendees?: Record<string, unknown>[];
   categories?: string[];
+  rrule?: Record<string, unknown> | null;
+  rdate?: Record<string, unknown>[];
+  exdate?: Record<string, unknown>[];
+  reminders?: Record<string, unknown>[];
+  attachments?: Record<string, unknown>[];
+  related_to?: Record<string, unknown>[];
+  source_kind?: string;
+  source_href?: string | null;
+  etag?: string | null;
+  icalendar?: Record<string, unknown>;
+  metadata?: Record<string, unknown>;
 };
 
 export type CalendarEventUpdatePayload = Partial<CalendarEventCreatePayload>;
@@ -110,6 +237,57 @@ export function deleteCalendar(settings: ApiSettings, calendarId: string, payloa
   return apiFetch<void>(settings, `/api/v1/calendar/calendars/${calendarId}`, { method: "DELETE", body: JSON.stringify(payload) });
 }
 
+export function listSyncSources(settings: ApiSettings, params: { calendar_id?: string; source_kind?: CalendarSyncSourceKind } = {}): Promise<CalendarSyncSourceListResponse> {
+  const search = new URLSearchParams();
+  if (params.calendar_id) search.set("calendar_id", params.calendar_id);
+  if (params.source_kind) search.set("source_kind", params.source_kind);
+  const suffix = search.toString() ? `?${search.toString()}` : "";
+  return apiFetch<CalendarSyncSourceListResponse>(settings, `/api/v1/calendar/sync-sources${suffix}`);
+}
+
+export function listCalDavSources(settings: ApiSettings, params: { calendar_id?: string } = {}): Promise<CalendarCalDavSourceListResponse> {
+  const search = new URLSearchParams();
+  if (params.calendar_id) search.set("calendar_id", params.calendar_id);
+  const suffix = search.toString() ? `?${search.toString()}` : "";
+  return apiFetch<CalendarCalDavSourceListResponse>(settings, `/api/v1/calendar/caldav/sources${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) });
+}
+
+export function createSyncSource(settings: ApiSettings, payload: CalendarSyncSourceCreatePayload): Promise<CalendarSyncSource> {
+  return apiFetch<CalendarSyncSource>(settings, "/api/v1/calendar/sync-sources", { method: "POST", body: JSON.stringify(payload) });
+}
+
+export function createCalDavSource(settings: ApiSettings, payload: CalendarCalDavSourceCreatePayload): Promise<CalendarCalDavSource> {
+  return apiFetch<CalendarCalDavSource>(settings, "/api/v1/calendar/caldav/sources", { method: "POST", body: JSON.stringify(payload) });
+}
+
+export function updateSyncSource(settings: ApiSettings, sourceId: string, payload: CalendarSyncSourceUpdatePayload): Promise<CalendarSyncSource> {
+  return apiFetch<CalendarSyncSource>(settings, `/api/v1/calendar/sync-sources/${sourceId}`, { method: "PATCH", body: JSON.stringify(payload) });
+}
+
+export function updateCalDavSource(settings: ApiSettings, sourceId: string, payload: CalendarCalDavSourceUpdatePayload): Promise<CalendarCalDavSource> {
+  return apiFetch<CalendarCalDavSource>(settings, `/api/v1/calendar/caldav/sources/${sourceId}`, { method: "PATCH", body: JSON.stringify(payload) });
+}
+
+export function deleteSyncSource(settings: ApiSettings, sourceId: string): Promise<void> {
+  return apiFetch<void>(settings, `/api/v1/calendar/sync-sources/${sourceId}`, { method: "DELETE" });
+}
+
+export function deleteCalDavSource(settings: ApiSettings, sourceId: string): Promise<void> {
+  return apiFetch<void>(settings, `/api/v1/calendar/caldav/sources/${sourceId}`, { method: "DELETE" });
+}
+
+export function syncSyncSource(settings: ApiSettings, sourceId: string, payload: CalendarSyncSourceSyncPayload = {}): Promise<CalendarSyncSourceSyncResponse> {
+  return apiFetch<CalendarSyncSourceSyncResponse>(settings, `/api/v1/calendar/sync-sources/${sourceId}/sync`, { method: "POST", body: JSON.stringify(payload) });
+}
+
+export function syncCalDavSource(settings: ApiSettings, sourceId: string, payload: CalendarCalDavSyncPayload = {}): Promise<CalendarCalDavSyncResponse> {
+  return apiFetch<CalendarCalDavSyncResponse>(settings, `/api/v1/calendar/caldav/sources/${sourceId}/sync`, { method: "POST", body: JSON.stringify(payload) });
+}
+
 export function listCalendarEvents(
   settings: ApiSettings,
   params: { calendar_id?: string; start_at?: string; end_at?: string } = {}
@@ -122,6 +300,20 @@ export function listCalendarEvents(
   return apiFetch<CalendarEventListResponse>(settings, `/api/v1/calendar/events${suffix}`);
 }
 
+export function listCalendarEventsDelta(
+  settings: ApiSettings,
+  params: { calendar_id?: string; start_at?: string; end_at?: string; since?: string | null; limit?: number } = {}
+): Promise<CalendarEventDeltaResponse> {
+  const search = new URLSearchParams();
+  if (params.calendar_id) search.set("calendar_id", params.calendar_id);
+  if (params.start_at) search.set("start_at", params.start_at);
+  if (params.end_at) search.set("end_at", params.end_at);
+  if (params.since) search.set("since", params.since);
+  if (params.limit) search.set("limit", String(params.limit));
+  const suffix = search.toString() ? `?${search.toString()}` : "";
+  return apiFetch<CalendarEventDeltaResponse>(settings, `/api/v1/calendar/events/delta${suffix}`);
+}
+
 export function createCalendarEvent(settings: ApiSettings, payload: CalendarEventCreatePayload): Promise<CalendarEvent> {
   return apiFetch<CalendarEvent>(settings, "/api/v1/calendar/events", { method: "POST", body: JSON.stringify(payload) });
 }

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

@@ -0,0 +1,380 @@
+import type { PlatformTranslations } from "@govoplan/core-webui";
+
+export const generatedTranslations: PlatformTranslations = {
+  "en": {
+    "i18n:govoplan-calendar.add_calendar.124c55eb": "Add calendar...",
+    "i18n:govoplan-calendar.add_calendar.8fadb5bc": "Add calendar",
+    "i18n:govoplan-calendar.add.61cc55aa": "Add",
+    "i18n:govoplan-calendar.advanced.4d064726": "Advanced",
+    "i18n:govoplan-calendar.agenda.891e9d6d": "Agenda",
+    "i18n:govoplan-calendar.all_day.11457433": "All day",
+    "i18n:govoplan-calendar.attachments_json.d91abf3c": "Attachments JSON",
+    "i18n:govoplan-calendar.attachments.6771ade6": "Attachments",
+    "i18n:govoplan-calendar.attendees_json.aeb487bb": "Attendees JSON",
+    "i18n:govoplan-calendar.attendees.a45a0962": "Attendees",
+    "i18n:govoplan-calendar.authentication.ee1acfa5": "Authentication",
+    "i18n:govoplan-calendar.automatic_sync.084644b2": "Automatic sync",
+    "i18n:govoplan-calendar.basic.aa2c96da": "Basic",
+    "i18n:govoplan-calendar.bearer_token.ffa64bcf": "Bearer token",
+    "i18n:govoplan-calendar.caldav_source.459ed16a": "CalDAV source",
+    "i18n:govoplan-calendar.caldav.64f9720e": "CalDAV",
+    "i18n:govoplan-calendar.calendar_controls.974f4fa1": "Calendar controls",
+    "i18n:govoplan-calendar.calendar_navigation.7ba43cd2": "Calendar navigation",
+    "i18n:govoplan-calendar.calendar_request_failed.ae8a54f4": "Calendar request failed.",
+    "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",
+    "i18n:govoplan-calendar.categories.6ccb6007": "Categories",
+    "i18n:govoplan-calendar.change_end_time.db66ef4b": "Change end time",
+    "i18n:govoplan-calendar.change_start_time.06eea3d3": "Change start time",
+    "i18n:govoplan-calendar.class.41ff354b": "Class",
+    "i18n:govoplan-calendar.color.1d0c8304": "Color",
+    "i18n:govoplan-calendar.confidential.84c9cc88": "CONFIDENTIAL",
+    "i18n:govoplan-calendar.configured.668c5fff": "Configured",
+    "i18n:govoplan-calendar.confirm_delete.c9f2829e": "Confirm delete",
+    "i18n:govoplan-calendar.confirmed.0542404a": "CONFIRMED",
+    "i18n:govoplan-calendar.conflict_policy.5810e150": "Conflict policy",
+    "i18n:govoplan-calendar.continuous.04f2ccda": "Continuous",
+    "i18n:govoplan-calendar.credential.8bede3ea": "Credential",
+    "i18n:govoplan-calendar.dav_url.4205e180": "DAV URL",
+    "i18n:govoplan-calendar.day.987b9ced": "Day",
+    "i18n:govoplan-calendar.delete_events_with_this_calendar.cc0e1287": "Delete events with this calendar",
+    "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...",
+    "i18n:govoplan-calendar.display_name.c7874aaa": "Display name",
+    "i18n:govoplan-calendar.duration_must_be_greater_than_zero.519292f7": "Duration must be greater than zero.",
+    "i18n:govoplan-calendar.duration_seconds.19d42eeb": "Duration seconds",
+    "i18n:govoplan-calendar.duration.1370004d": "Duration",
+    "i18n:govoplan-calendar.edit_calendar.a47a2a7a": "Edit calendar",
+    "i18n:govoplan-calendar.edit_event.a7028454": "Edit event",
+    "i18n:govoplan-calendar.edit_value.fad75899": "Edit {value0}",
+    "i18n:govoplan-calendar.end_date_and_time_must_be_after_start_date_and_t.daf31831": "End date and time must be after start date and time.",
+    "i18n:govoplan-calendar.end_date_must_be_on_or_after_start_date.a2518865": "End date must be on or after start date.",
+    "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_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",
+    "i18n:govoplan-calendar.icalendar.f388476d": "iCalendar",
+    "i18n:govoplan-calendar.ics_webcal_subscription.03bc0d63": "ICS/webcal subscription",
+    "i18n:govoplan-calendar.ics_webcal.9c55b570": "ICS/webcal",
+    "i18n:govoplan-calendar.identity.7e5a975b": "Identity",
+    "i18n:govoplan-calendar.inbound_only.bf4269b0": "Inbound only",
+    "i18n:govoplan-calendar.interval.011efcd5": "Interval",
+    "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",
+    "i18n:govoplan-calendar.location.d219c681": "Location",
+    "i18n:govoplan-calendar.make_target_calendar_the_default.10a3977b": "Make target calendar the default",
+    "i18n:govoplan-calendar.managing_sync_sources_requires_calendar_administ.835e29fa": "Managing sync sources requires calendar administration rights.",
+    "i18n:govoplan-calendar.metadata_json.b0e4c283": "Metadata JSON",
+    "i18n:govoplan-calendar.metadata.251edc0e": "Metadata",
+    "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",
+    "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": "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",
+    "i18n:govoplan-calendar.not_synced.4c205136": "Not synced",
+    "i18n:govoplan-calendar.opaque.3e1d0194": "OPAQUE",
+    "i18n:govoplan-calendar.organizer_json.3add6f9f": "Organizer JSON",
+    "i18n:govoplan-calendar.organizer.debd1720": "Organizer",
+    "i18n:govoplan-calendar.overwrite_remote.39625e32": "Overwrite remote",
+    "i18n:govoplan-calendar.participants.cd56e083": "Participants",
+    "i18n:govoplan-calendar.password.8be3c943": "Password",
+    "i18n:govoplan-calendar.previous.50f94286": "Previous",
+    "i18n:govoplan-calendar.private.b0b7ba46": "PRIVATE",
+    "i18n:govoplan-calendar.public.d1785ca2": "PUBLIC",
+    "i18n:govoplan-calendar.raw.da433cd4": "Raw",
+    "i18n:govoplan-calendar.rdate_json.5b51fca4": "RDATE JSON",
+    "i18n:govoplan-calendar.recurrence_id.e0b780ba": "Recurrence ID",
+    "i18n:govoplan-calendar.recurrence.f7ad40f5": "Recurrence",
+    "i18n:govoplan-calendar.refresh.56e3badc": "Refresh",
+    "i18n:govoplan-calendar.related_to_json.2d4e8f59": "Related-To JSON",
+    "i18n:govoplan-calendar.related_to.0e7989ff": "Related-To",
+    "i18n:govoplan-calendar.related.917df91e": "Related",
+    "i18n:govoplan-calendar.reminders_json.ca25e08f": "Reminders JSON",
+    "i18n:govoplan-calendar.reminders.ae8c3939": "Reminders",
+    "i18n:govoplan-calendar.remove_local_events_with_this_calendar.fb8831e1": "Remove local events with this calendar",
+    "i18n:govoplan-calendar.remove.e963907d": "Remove",
+    "i18n:govoplan-calendar.removing.b7d2c38b": "Removing",
+    "i18n:govoplan-calendar.replace_password.3f912c9c": "Replace password",
+    "i18n:govoplan-calendar.replace_token.bbeee6a9": "Replace token",
+    "i18n:govoplan-calendar.require_matching_etag.0ab1ffe1": "Require matching ETag",
+    "i18n:govoplan-calendar.rrule.c7b2f8a3": "RRULE",
+    "i18n:govoplan-calendar.sat.6b782d41": "Sat",
+    "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",
+    "i18n:govoplan-calendar.source.6da13add": "Source",
+    "i18n:govoplan-calendar.start_date.ff99f5b5": "Start date",
+    "i18n:govoplan-calendar.start_time.88d8206d": "Start time",
+    "i18n:govoplan-calendar.state.a7250206": "State",
+    "i18n:govoplan-calendar.status.bae7d5be": "Status",
+    "i18n:govoplan-calendar.subscription_url.b8b6a1a0": "Subscription URL",
+    "i18n:govoplan-calendar.sun.48c98cab": "Sun",
+    "i18n:govoplan-calendar.sync_now.2b7d938e": "Sync now",
+    "i18n:govoplan-calendar.sync_value.72e4ba66": "Sync {value0}",
+    "i18n:govoplan-calendar.syncing_value.ca80b487": "Syncing {value0}",
+    "i18n:govoplan-calendar.syncing.4ae6fa22": "Syncing",
+    "i18n:govoplan-calendar.syncing.e5c7727a": "Syncing...",
+    "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",
+    "i18n:govoplan-calendar.today.24345a14": "Today",
+    "i18n:govoplan-calendar.transparency.7cb338a9": "Transparency",
+    "i18n:govoplan-calendar.transparent.ea4efcae": "TRANSPARENT",
+    "i18n:govoplan-calendar.tue.529541bb": "Tue",
+    "i18n:govoplan-calendar.two_way.ee50a3e6": "Two-way",
+    "i18n:govoplan-calendar.uid.d946adf5": "UID",
+    "i18n:govoplan-calendar.username.84c29015": "Username",
+    "i18n:govoplan-calendar.value_this_calendar_will_delete_value_value.7869d1f1": "{value0} this calendar will delete {value1} {value2}.",
+    "i18n:govoplan-calendar.value_this_calendar_will_move_value_value_to_val.6c87e1c1": "{value0} this calendar will move {value1} {value2} to {value3}.",
+    "i18n:govoplan-calendar.value_this_calendar_will_remove_value_local_valu.8f21a59e": "{value0} this calendar will remove {value1} local {value2} from GovOPlaN.",
+    "i18n:govoplan-calendar.vevent.9cf5be75": "VEVENT",
+    "i18n:govoplan-calendar.wed.23408b19": "Wed",
+    "i18n:govoplan-calendar.week.f82be68a": "Week",
+    "i18n:govoplan-calendar.whole_day.951c82d1": "Whole day",
+    "i18n:govoplan-calendar.working.049ac820": "Working...",
+    "i18n:govoplan-calendar.workweek.2fef6ea4": "Workweek"
+  },
+  "de": {
+    "i18n:govoplan-calendar.add_calendar.124c55eb": "Add calendar...",
+    "i18n:govoplan-calendar.add_calendar.8fadb5bc": "Add calendar",
+    "i18n:govoplan-calendar.add.61cc55aa": "Hinzufügen",
+    "i18n:govoplan-calendar.advanced.4d064726": "Advanced",
+    "i18n:govoplan-calendar.agenda.891e9d6d": "Agenda",
+    "i18n:govoplan-calendar.all_day.11457433": "Ganztägig",
+    "i18n:govoplan-calendar.attachments_json.d91abf3c": "Attachments JSON",
+    "i18n:govoplan-calendar.attachments.6771ade6": "Attachments",
+    "i18n:govoplan-calendar.attendees_json.aeb487bb": "Attendees JSON",
+    "i18n:govoplan-calendar.attendees.a45a0962": "Attendees",
+    "i18n:govoplan-calendar.authentication.ee1acfa5": "Authentication",
+    "i18n:govoplan-calendar.automatic_sync.084644b2": "Automatic sync",
+    "i18n:govoplan-calendar.basic.aa2c96da": "Basic",
+    "i18n:govoplan-calendar.bearer_token.ffa64bcf": "Bearer token",
+    "i18n:govoplan-calendar.caldav_source.459ed16a": "CalDAV source",
+    "i18n:govoplan-calendar.caldav.64f9720e": "CalDAV",
+    "i18n:govoplan-calendar.calendar_controls.974f4fa1": "Calendar controls",
+    "i18n:govoplan-calendar.calendar_navigation.7ba43cd2": "Calendar navigation",
+    "i18n:govoplan-calendar.calendar_request_failed.ae8a54f4": "Calendar request failed.",
+    "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",
+    "i18n:govoplan-calendar.categories.6ccb6007": "Categories",
+    "i18n:govoplan-calendar.change_end_time.db66ef4b": "Change end time",
+    "i18n:govoplan-calendar.change_start_time.06eea3d3": "Change start time",
+    "i18n:govoplan-calendar.class.41ff354b": "Class",
+    "i18n:govoplan-calendar.color.1d0c8304": "Color",
+    "i18n:govoplan-calendar.confidential.84c9cc88": "CONFIDENTIAL",
+    "i18n:govoplan-calendar.configured.668c5fff": "Configured",
+    "i18n:govoplan-calendar.confirm_delete.c9f2829e": "Confirm delete",
+    "i18n:govoplan-calendar.confirmed.0542404a": "CONFIRMED",
+    "i18n:govoplan-calendar.conflict_policy.5810e150": "Conflict policy",
+    "i18n:govoplan-calendar.continuous.04f2ccda": "Continuous",
+    "i18n:govoplan-calendar.credential.8bede3ea": "Credential",
+    "i18n:govoplan-calendar.dav_url.4205e180": "DAV URL",
+    "i18n:govoplan-calendar.day.987b9ced": "Tag",
+    "i18n:govoplan-calendar.delete_events_with_this_calendar.cc0e1287": "Delete events with this calendar",
+    "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...",
+    "i18n:govoplan-calendar.display_name.c7874aaa": "Anzeigename",
+    "i18n:govoplan-calendar.duration_must_be_greater_than_zero.519292f7": "Duration must be greater than zero.",
+    "i18n:govoplan-calendar.duration_seconds.19d42eeb": "Duration seconds",
+    "i18n:govoplan-calendar.duration.1370004d": "Duration",
+    "i18n:govoplan-calendar.edit_calendar.a47a2a7a": "Edit calendar",
+    "i18n:govoplan-calendar.edit_event.a7028454": "Termin bearbeiten",
+    "i18n:govoplan-calendar.edit_value.fad75899": "Edit {value0}",
+    "i18n:govoplan-calendar.end_date_and_time_must_be_after_start_date_and_t.daf31831": "End date and time must be after start date and time.",
+    "i18n:govoplan-calendar.end_date_must_be_on_or_after_start_date.a2518865": "End date must be on or after start date.",
+    "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_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",
+    "i18n:govoplan-calendar.icalendar.f388476d": "iCalendar",
+    "i18n:govoplan-calendar.ics_webcal_subscription.03bc0d63": "ICS/webcal subscription",
+    "i18n:govoplan-calendar.ics_webcal.9c55b570": "ICS/webcal",
+    "i18n:govoplan-calendar.identity.7e5a975b": "Identity",
+    "i18n:govoplan-calendar.inbound_only.bf4269b0": "Inbound only",
+    "i18n:govoplan-calendar.interval.011efcd5": "Interval",
+    "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",
+    "i18n:govoplan-calendar.location.d219c681": "Ort",
+    "i18n:govoplan-calendar.make_target_calendar_the_default.10a3977b": "Make target calendar the default",
+    "i18n:govoplan-calendar.managing_sync_sources_requires_calendar_administ.835e29fa": "Managing sync sources requires calendar administration rights.",
+    "i18n:govoplan-calendar.metadata_json.b0e4c283": "Metadata JSON",
+    "i18n:govoplan-calendar.metadata.251edc0e": "Metadata",
+    "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_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",
+    "i18n:govoplan-calendar.not_synced.4c205136": "Not synced",
+    "i18n:govoplan-calendar.opaque.3e1d0194": "OPAQUE",
+    "i18n:govoplan-calendar.organizer_json.3add6f9f": "Organizer JSON",
+    "i18n:govoplan-calendar.organizer.debd1720": "Organizer",
+    "i18n:govoplan-calendar.overwrite_remote.39625e32": "Overwrite remote",
+    "i18n:govoplan-calendar.participants.cd56e083": "Participants",
+    "i18n:govoplan-calendar.password.8be3c943": "Passwort",
+    "i18n:govoplan-calendar.previous.50f94286": "Previous",
+    "i18n:govoplan-calendar.private.b0b7ba46": "PRIVATE",
+    "i18n:govoplan-calendar.public.d1785ca2": "PUBLIC",
+    "i18n:govoplan-calendar.raw.da433cd4": "Raw",
+    "i18n:govoplan-calendar.rdate_json.5b51fca4": "RDATE JSON",
+    "i18n:govoplan-calendar.recurrence_id.e0b780ba": "Recurrence ID",
+    "i18n:govoplan-calendar.recurrence.f7ad40f5": "Wiederholung",
+    "i18n:govoplan-calendar.refresh.56e3badc": "Refresh",
+    "i18n:govoplan-calendar.related_to_json.2d4e8f59": "Related-To JSON",
+    "i18n:govoplan-calendar.related_to.0e7989ff": "Related-To",
+    "i18n:govoplan-calendar.related.917df91e": "Related",
+    "i18n:govoplan-calendar.reminders_json.ca25e08f": "Reminders JSON",
+    "i18n:govoplan-calendar.reminders.ae8c3939": "Reminders",
+    "i18n:govoplan-calendar.remove_local_events_with_this_calendar.fb8831e1": "Remove local events with this calendar",
+    "i18n:govoplan-calendar.remove.e963907d": "Remove",
+    "i18n:govoplan-calendar.removing.b7d2c38b": "Removing",
+    "i18n:govoplan-calendar.replace_password.3f912c9c": "Replace password",
+    "i18n:govoplan-calendar.replace_token.bbeee6a9": "Replace token",
+    "i18n:govoplan-calendar.require_matching_etag.0ab1ffe1": "Require matching ETag",
+    "i18n:govoplan-calendar.rrule.c7b2f8a3": "RRULE",
+    "i18n:govoplan-calendar.sat.6b782d41": "Sat",
+    "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",
+    "i18n:govoplan-calendar.source.6da13add": "Quelle",
+    "i18n:govoplan-calendar.start_date.ff99f5b5": "Start date",
+    "i18n:govoplan-calendar.start_time.88d8206d": "Start time",
+    "i18n:govoplan-calendar.state.a7250206": "State",
+    "i18n:govoplan-calendar.status.bae7d5be": "Status",
+    "i18n:govoplan-calendar.subscription_url.b8b6a1a0": "Subscription URL",
+    "i18n:govoplan-calendar.sun.48c98cab": "Sun",
+    "i18n:govoplan-calendar.sync_now.2b7d938e": "Sync now",
+    "i18n:govoplan-calendar.sync_value.72e4ba66": "Sync {value0}",
+    "i18n:govoplan-calendar.syncing_value.ca80b487": "Syncing {value0}",
+    "i18n:govoplan-calendar.syncing.4ae6fa22": "Syncing",
+    "i18n:govoplan-calendar.syncing.e5c7727a": "Syncing...",
+    "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",
+    "i18n:govoplan-calendar.today.24345a14": "Heute",
+    "i18n:govoplan-calendar.transparency.7cb338a9": "Transparency",
+    "i18n:govoplan-calendar.transparent.ea4efcae": "TRANSPARENT",
+    "i18n:govoplan-calendar.tue.529541bb": "Tue",
+    "i18n:govoplan-calendar.two_way.ee50a3e6": "Two-way",
+    "i18n:govoplan-calendar.uid.d946adf5": "UID",
+    "i18n:govoplan-calendar.username.84c29015": "Benutzername",
+    "i18n:govoplan-calendar.value_this_calendar_will_delete_value_value.7869d1f1": "{value0} this calendar will delete {value1} {value2}.",
+    "i18n:govoplan-calendar.value_this_calendar_will_move_value_value_to_val.6c87e1c1": "{value0} this calendar will move {value1} {value2} to {value3}.",
+    "i18n:govoplan-calendar.value_this_calendar_will_remove_value_local_valu.8f21a59e": "{value0} this calendar will remove {value1} local {value2} from GovOPlaN.",
+    "i18n:govoplan-calendar.vevent.9cf5be75": "VEVENT",
+    "i18n:govoplan-calendar.wed.23408b19": "Wed",
+    "i18n:govoplan-calendar.week.f82be68a": "Woche",
+    "i18n:govoplan-calendar.whole_day.951c82d1": "Whole day",
+    "i18n:govoplan-calendar.working.049ac820": "Working...",
+    "i18n:govoplan-calendar.workweek.2fef6ea4": "Workweek"
+  }
+};

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

@@ -1,21 +1,33 @@
 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"));
 
 const eventRead = ["calendar:event:read"];
+const translations = {
+  en: generatedTranslations.en,
+  de: generatedTranslations.de
+};
+
+const calendarPicker: CalendarPickerUiCapability = { CalendarPicker };
 
 export const calendarModule: PlatformWebModule = {
   id: "calendar",
-  label: "Calendar",
+  label: "i18n:govoplan-calendar.calendar.adab5090",
   version: "1.0.0",
   dependencies: ["access"],
   optionalDependencies: ["mail", "tasks", "scheduling", "appointments", "workflow", "notifications", "dms", "connectors"],
-  navItems: [{ to: "/calendar", label: "Calendar", iconName: "calendar", anyOf: eventRead, order: 55 }],
+  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
+  }
+
 };
 
 export default calendarModule;

webui/src/styles/calendar.css

@@ -17,13 +17,18 @@
   box-sizing: border-box;
 }
 
+.calendar-loading-frame {
+  min-height: 0;
+  height: 100%;
+}
+
 .calendar-shell {
   min-height: 0;
   height: 100%;
   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);
 }
@@ -46,7 +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);
 }
 
@@ -84,76 +89,15 @@
   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;
-  display: inline-grid;
   grid-template-columns: repeat(5, minmax(0, 1fr));
   width: min(520px, 100%);
   max-width: 520px;
-  overflow: hidden;
-  border: 1px solid #c9c3b9;
-  border-radius: 8px;
-  background: #c9c3b9;
-  box-shadow: inset 0 1px 0 rgba(255,255,255,.75), 0 1px 1px rgba(0,0,0,.05);
 }
 
-.calendar-mode-tab {
+.calendar-mode-switch .segmented-control-option {
   min-height: 34px;
-  border: 0;
-  border-radius: 0;
-  background: linear-gradient(#ffffff, #f1efeb);
-  color: #4f4a43;
-  cursor: pointer;
-  font: inherit;
-  font-size: 13px;
-  font-weight: 800;
-  box-shadow: inset 0 1px 0 rgba(255,255,255,.75), 0 1px 1px rgba(0,0,0,.05);
-  transition: background .18s ease, box-shadow .18s ease, color .18s ease;
-}
-
-.calendar-mode-tab + .calendar-mode-tab {
-  border-left: 1px solid #c9c3b9;
-}
-
-.calendar-mode-tab:first-child {
-  border-radius: 7px 0 0 7px;
-}
-
-.calendar-mode-tab:last-child {
-  border-radius: 0 7px 7px 0;
-}
-
-.calendar-mode-tab:hover,
-.calendar-mode-tab:focus-visible {
-  background: linear-gradient(#ffffff, #e8e5df);
-  color: #4f4a43;
-  box-shadow: inset 0 1px 0 rgba(255,255,255,.82), 0 2px 5px rgba(0,0,0,.08);
-}
-
-.calendar-mode-tab:focus-visible {
-  outline: 3px solid rgba(82, 130, 177, .22);
-  outline-offset: -1px;
-}
-
-.calendar-mode-tab.is-active {
-  background: var(--line);
-  color: var(--text-strong);
-  box-shadow: inset 0 2px 5px rgba(0,0,0,.12), inset 0 -1px 0 rgba(255,255,255,.45);
 }
 
 .calendar-sidebar {
@@ -162,14 +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;
@@ -178,7 +122,7 @@
 }
 
 .calendar-sidebar-heading.is-secondary {
-  border-top: 1px solid var(--line);
+  border-top: var(--border-line);
 }
 
 .calendar-list,
@@ -216,7 +160,7 @@
 .calendar-list-row {
   min-width: 0;
   display: grid;
-  grid-template-columns: 42px minmax(0, 1fr) 30px;
+  grid-template-columns: 42px minmax(0, 1fr) auto;
   align-items: center;
   gap: 4px;
   min-height: 36px;
@@ -230,6 +174,10 @@
   background: var(--panel-soft);
 }
 
+.calendar-list-row.is-syncing {
+  background: var(--panel-soft);
+}
+
 .calendar-visibility-switch {
   --calendar-list-color: var(--green);
   width: 34px;
@@ -238,9 +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;
 }
@@ -254,8 +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;
 }
@@ -286,64 +234,36 @@
   outline: none;
 }
 
-.calendar-row-icon-button.btn {
+.calendar-list-actions {
-  width: 28px;
+  width: auto;
-  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-sync-spin {
-.calendar-row-icon-button.btn:focus-visible {
+  animation: calendar-sync-spin .85s linear infinite;
-  border-color: var(--line-dark);
-  background: var(--surface);
-  opacity: 1;
 }
 
-.calendar-create-form input[type="color"] {
+@keyframes calendar-sync-spin {
-  width: 24px;
+  to {
-  min-width: 24px;
+    transform: rotate(360deg);
-  height: 24px;
+  }
-  padding: 0;
-  overflow: hidden;
-  border: 1px solid var(--line-dark);
-  border-radius: 4px;
-  background: transparent;
-  cursor: pointer;
 }
 
-.calendar-create-form input:disabled {
+@media (prefers-reduced-motion: reduce) {
-  opacity: .55;
+  .calendar-sync-spin {
-  cursor: not-allowed;
+    animation: none;
+  }
 }
 
-.calendar-create-form {
+.calendar-create-action {
   min-width: 0;
-  display: grid;
-  grid-template-columns: minmax(0, 1fr) 28px 36px;
-  align-items: center;
-  gap: 6px;
   margin-top: 6px;
   padding-top: 8px;
-  border-top: 1px solid var(--line);
+  border-top: var(--border-line);
 }
 
-.calendar-create-form input[type="text"],
+.calendar-create-action .btn {
-.calendar-create-form input:not([type]) {
+  width: 100%;
-  min-width: 0;
+  justify-content: center;
-  height: 34px;
-  border: 1px solid var(--line-dark);
-  border-radius: 4px;
-  background: var(--surface);
-  color: var(--text);
-  font: inherit;
-  padding: 6px 8px;
 }
 
 .calendar-agenda {
@@ -363,7 +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 {
@@ -378,15 +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 {
@@ -401,7 +321,7 @@
 .calendar-agenda-item .calendar-event-separator,
 .calendar-agenda p {
   margin: 0;
-  color: #4d6764;
+  color: var(--calendar-event-muted-text);
   font-size: 12px;
 }
 
@@ -433,9 +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 {
@@ -471,7 +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);
 }
 
@@ -491,7 +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 {
@@ -508,22 +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 {
@@ -531,7 +451,7 @@
 }
 
 .calendar-day-cell.is-drop-target {
-  background: #e3f3ef;
+  background: var(--calendar-today-bg);
   box-shadow: inset 0 0 0 2px var(--green);
 }
 
@@ -567,8 +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;
@@ -577,7 +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;
@@ -629,7 +549,7 @@
 .calendar-event-time,
 .calendar-event-separator {
   flex: 0 0 auto;
-  color: #4d6764;
+  color: var(--calendar-event-muted-text);
 }
 
 .calendar-more-events {
@@ -667,8 +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);
 }
 
@@ -681,12 +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 {
@@ -697,7 +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 {
@@ -715,7 +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);
 }
 
@@ -744,8 +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;
@@ -756,17 +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,
@@ -778,11 +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 {
@@ -810,10 +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;
@@ -831,15 +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;
 }
@@ -849,8 +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;
 }
 
@@ -869,7 +789,7 @@
 }
 
 .calendar-timed-event-content:focus-visible {
-  outline: 2px solid rgba(90, 169, 155, .35);
+  outline: var(--calendar-focus-outline);
   outline-offset: -2px;
 }
 
@@ -896,7 +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%);
@@ -922,7 +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;
@@ -931,7 +851,11 @@
 }
 
 .calendar-event-dialog {
-  width: min(560px, 100%);
+  width: min(680px, 100%);
+}
+
+.calendar-vevent-dialog {
+  width: min(920px, 100%);
 }
 
 .calendar-dialog-form {
@@ -974,22 +898,213 @@
 
 .calendar-dialog-name-color-row {
   display: grid;
-  grid-template-columns: minmax(0, 1fr) 86px;
+  grid-template-columns: minmax(0, 1fr) 142px;
   gap: 12px;
 }
 
-.calendar-dialog-color-label input[type="color"] {
+.calendar-source-switch {
+  grid-template-columns: repeat(auto-fit, minmax(104px, 1fr));
   width: 100%;
+}
+
+.calendar-source-switch .segmented-control-option {
+  min-height: 34px;
+}
+
+.calendar-source-pane {
+  display: grid;
+  gap: 12px;
+  padding: 12px;
+  border: var(--border-line);
+  border-radius: 6px;
+  background: var(--panel-soft);
+}
+
+.calendar-source-pane h3 {
+  margin: 0;
+  color: var(--text-strong);
+  font-size: 14px;
+}
+
+.calendar-source-pane-heading,
+.calendar-sync-actions {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 10px;
+}
+
+.calendar-dialog-grid-two,
+.calendar-dialog-grid-three,
+.calendar-caldav-setup,
+.calendar-sync-settings {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 12px;
+}
+
+.calendar-dialog-grid-three {
+  grid-template-columns: repeat(3, minmax(0, 1fr));
+}
+
+.calendar-dialog-wide {
+  grid-column: 1 / -1;
+}
+
+.calendar-caldav-setup {
+  align-items: end;
+}
+
+.calendar-discovery-actions {
+  grid-column: 1 / -1;
+  display: flex;
+  align-items: center;
+  gap: 10px;
   min-width: 0;
-  padding: 3px;
+}
+
+.calendar-discovery-actions .btn {
+  flex: 0 0 auto;
+}
+
+.calendar-discovery-actions span {
+  min-width: 0;
+  overflow: hidden;
+  color: var(--muted);
+  font-size: 12px;
+  font-weight: 700;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.calendar-discovery-actions.is-readonly {
+  justify-content: flex-start;
+}
+
+.calendar-advanced-settings {
+  display: grid;
+  gap: 12px;
+}
+
+.calendar-advanced-settings summary {
+  width: fit-content;
+  cursor: pointer;
+  color: var(--text-strong);
+  font-size: 13px;
+  font-weight: 800;
+}
+
+.calendar-advanced-settings[open] {
+  gap: 12px;
+}
+
+.calendar-advanced-settings[open] summary {
+  margin-bottom: 12px;
+}
+
+.calendar-vevent-details {
+  border-top: var(--border-line);
+  padding-top: 4px;
+}
+
+.calendar-vevent-section {
+  display: grid;
+  gap: 10px;
+  padding: 12px 0;
+  border-top: var(--border-line);
+}
+
+.calendar-vevent-section:first-of-type {
+  border-top: 0;
+  padding-top: 0;
+}
+
+.calendar-vevent-section h3 {
+  margin: 0;
+  color: var(--text-strong);
+  font-size: 13px;
+}
+
+.calendar-vevent-section textarea {
+  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
+  font-size: 12px;
+  line-height: 1.45;
+}
+
+.calendar-sync-settings {
+  align-items: end;
+}
+
+.calendar-sync-status {
+  padding: 3px 8px;
+  border: var(--border-line-dark);
+  border-radius: 999px;
+  background: var(--surface);
+  color: var(--muted);
+  font-size: 12px;
+  font-weight: 800;
+}
+
+.calendar-sync-status.is-error {
+  border-color: var(--calendar-danger-border);
+  background: var(--calendar-danger-bg);
+  color: var(--red);
+}
+
+.calendar-sync-status.is-syncing {
+  border-color: var(--green);
+  background: var(--surface);
+  color: var(--green);
+}
+
+.calendar-sync-button.btn.is-syncing,
+.calendar-sync-button.btn.is-syncing:disabled {
+  opacity: 1;
+  cursor: progress;
+}
+
+.calendar-sync-status-panel {
+  display: grid;
+  gap: 10px;
+  padding: 10px;
+  border: var(--border-line);
+  border-radius: 6px;
+  background: var(--surface);
+}
+
+.calendar-sync-status-panel dl {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 8px 14px;
+  margin: 0;
+}
+
+.calendar-sync-status-panel dl div {
+  min-width: 0;
+}
+
+.calendar-sync-status-panel dt {
+  color: var(--muted);
+  font-size: 11px;
+  font-weight: 800;
+  text-transform: uppercase;
+}
+
+.calendar-sync-status-panel dd {
+  margin: 2px 0 0;
+  overflow: hidden;
+  color: var(--text);
+  font-size: 13px;
+  text-overflow: ellipsis;
+  white-space: nowrap;
 }
 
 .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;
 }
@@ -1003,13 +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);
 }
@@ -1019,7 +1134,7 @@
   gap: 10px;
   margin: 0;
   padding: 10px;
-  border: 1px solid var(--line);
+  border: var(--border-line);
   border-radius: 6px;
   background: var(--panel-soft);
 }
@@ -1056,6 +1171,15 @@
   color: var(--muted);
 }
 
+.calendar-delete-dialog {
+  width: min(520px, 100%);
+}
+
+.calendar-delete-dialog-body {
+  display: grid;
+  gap: 12px;
+}
+
 .calendar-event-dialog-footer {
   justify-content: space-between;
   gap: 12px;
@@ -1103,7 +1227,7 @@
 
   .calendar-sidebar {
     border-right: 0;
-    border-bottom: 1px solid var(--line);
+    border-bottom: var(--border-line);
   }
 
   .calendar-mode-switch {
@@ -1114,7 +1238,12 @@
 
   .calendar-dialog-row,
   .calendar-dialog-date-row,
-  .calendar-dialog-name-color-row {
+  .calendar-dialog-name-color-row,
+  .calendar-dialog-grid-two,
+  .calendar-dialog-grid-three,
+  .calendar-caldav-setup,
+  .calendar-sync-settings,
+  .calendar-sync-status-panel dl {
     grid-template-columns: 1fr;
   }
 }

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"
+  ]
+}