cal_add: bare ISO timestamps default to UTC, events created in wrong time slot

[BrewingCoder]

Bug

When cal_add receives bare ISO 8601 timestamps (no offset or timezone), the Graph API defaults to UTC. This causes events to be created shifted from the user's intended local time.

Reproduction

Two events created via MCP cal_add:

{"title": "Dogs to groomers", "start": "2026-03-06T06:30:00", "end": "2026-03-06T08:00:00"}
{"title": "Pickup dogs from groomers", "start": "2026-03-06T12:00:00", "end": "2026-03-06T13:30:00"}

First event landed in the correct slot. Second event was shifted — both were interpreted as UTC, 5 hours ahead of the user's Eastern timezone.

Root Cause

The Graph API event resource expects a object with both and fields:

{
  "start": {"dateTime": "2026-03-06T12:00:00", "timeZone": "Eastern Standard Time"},
  "end": {"dateTime": "2026-03-06T13:30:00", "timeZone": "Eastern Standard Time"}
}

Outpost currently sends the bare dateTime without a timeZone property, so Graph defaults to UTC.

Proposed Fix

1. Add a timezone config setting (set during outpost setup, stored in config.json, e.g. "America/New_York")
2. When building the event payload in api/calendar.py, include timeZone in the start/end objects using the configured timezone
3. Add an optional --timezone flag to cal add / cal update CLI and MCP tools for per-event override
4. Fall back to UTC if no timezone is configured (current behavior, but explicit)

Affected Components

• src/outpost/api/calendar.py — event payload construction
• src/outpost/cli/calendar.py — CLI parameter
• src/outpost/mcp_server.py — MCP tool parameter
• src/outpost/config.py — timezone config setting
• outpost setup — timezone prompt

[github-actions]

Triage Summary

Priority: 🟠 high
Component: calendar

Events are being created in the wrong time slot when bare ISO timestamps are provided, as the Graph API defaults to UTC instead of the user's local timezone. This is a blocking issue for calendar functionality that affects data accuracy and user experience.

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