| name | calin |
| description | Sync any ICS/iCal calendar to Microsoft Exchange as blocked time slots — supports recurring events, change detection, and privacy-preserving sync |
| version | 1.0.0 |
| metadata | {"clawdbot":{"os":["darwin"],"requires":{"env":"[Truncated]","bins":"[Truncated]","config":"[Truncated]"},"primaryEnv":"CALINT_ICS_URL","files":["*.py","install.sh","requirements.txt"]},"homepage":"https://github.com/Blucaru/CalIn"} |
CalIn — ICS Calendar to Exchange Sync
Sync busy time from any ICS/iCal calendar to Microsoft Exchange as "Blocked" slots. Works with Google Calendar, iCloud, Outlook.com, Nextcloud, Fastmail, Proton Calendar, or any CalDAV server that publishes an ICS feed.
When to Use This Skill
- User asks to sync calendars, block time, or mirror busy slots
- User wants personal calendar events to block time on their work calendar
- User asks to check sync status or clear synced events
- Scheduled background sync via Heartbeat (recommended: every 5-30 minutes)
What It Does
- Fetches events (including recurring) from any HTTPS ICS feed
- Creates/updates/deletes corresponding "Blocked" events on Exchange via Microsoft Graph API
- Tracks synced events with a local mapping file — only touches what changed
- Privacy-preserving: only syncs time slots, never event titles, descriptions, or attendees
Setup
1. Install dependencies
Requires Python 3.12+.
cd ~/.openclaw/skills/calin
bash install.sh
This creates a Python venv and installs icalendar, msal, recurring-ical-events, and requests.
2. Configure credentials
Add to ~/.calintegration/.env (created by installer with chmod 600):
CALINT_ICS_URL=<your-ics-feed-url>
CALINT_MS_CLIENT_ID=<azure-app-client-id>
CALINT_MS_TENANT_ID=<azure-app-tenant-id>
# Optional: sync to a specific Exchange calendar (defaults to primary)
# CALINT_MS_CALENDAR_ID=<calendar-id>
Where to find your ICS URL:
| Provider | Location |
|---|
| Google Calendar | Settings > your calendar > Integrate > "Secret address in iCal format" |
| iCloud | Calendar app > right-click calendar > Share > Public Calendar > copy URL |
| Outlook.com | Settings > Calendar > Shared calendars > Publish > ICS link |
| Nextcloud | Calendar > three-dot menu > Copy subscription link |
| Fastmail | Settings > Calendars > Share/export > ICS URL |
Azure AD app (free, no client secret needed):
- Go to https://portal.azure.com/#view/Microsoft_AAD_RegisteredApps/ApplicationsListBlade
- New registration > Name: "CalIn" > Redirect URI: Public client >
http://localhost:8400
- API permissions > Add > Microsoft Graph > Delegated > Calendars.ReadWrite
- Copy Application (client) ID and Directory (tenant) ID
3. Authenticate Microsoft
cd ~/.openclaw/skills/calin
venv/bin/python main.py setup
This opens a browser for one-time Microsoft login. Tokens are cached locally.
Commands
Run these from the skill directory:
| Command | What it does |
|---|
venv/bin/python main.py sync | Run one sync cycle |
venv/bin/python main.py status | Show last sync time and event count |
venv/bin/python main.py clear | Remove all synced events from Exchange |
venv/bin/python main.py setup | Re-run authentication setup |
Automated Sync (macOS)
The installer generates a launchd plist for automatic sync every 5 minutes:
cd ~/.openclaw/skills/calin
bash install.sh
cp com.calintegration.sync.plist ~/Library/LaunchAgents/
launchctl load ~/Library/LaunchAgents/com.calintegration.sync.plist
How It Works
- Fetches the ICS feed and expands all recurring events within a 14-day window
- Compares against the local event map (previous sync state)
- For each event:
- New: Creates a "Blocked" event on Exchange
- Changed (time moved): Updates the Exchange event
- Deleted from source: Deletes the Exchange event
- Saves updated event map and last sync timestamp
Change detection uses a hash of start time + end time + all-day flag. Only changed events trigger API calls.
Security and Privacy
- Credentials stored in
~/.calintegration/.env with chmod 600 permissions
- Tokens stored in
~/.calintegration/ms_token.json with chmod 600 permissions
- All files in
~/.calintegration/ directory with chmod 700
- No event details synced — only time slots are transmitted. Event titles, descriptions, attendees, and locations are never sent to Exchange
- HTTPS only — ICS URLs must use HTTPS; Graph API calls use TLS with certificate verification
- No client secret — uses PKCE (Proof Key for Code Exchange) for Microsoft auth
- ICS URL validated — rejects non-HTTPS schemes to prevent SSRF
- API path IDs validated — prevents injection in Graph API endpoint construction
- All HTTP requests have 30-second timeouts to prevent hanging
External endpoints called
| Endpoint | Purpose | Auth |
|---|
| Your ICS URL (HTTPS) | Read calendar events | URL contains secret token |
login.microsoftonline.com | Microsoft OAuth token exchange | PKCE flow |
graph.microsoft.com/v1.0 | Create/update/delete Exchange events | Bearer token |
Data flow
ICS Feed (read-only) --> [CalIn on your machine] --> Microsoft Graph API (write)
|
~/.calintegration/ (local state)
No data is sent to any third party. All processing happens locally.
