A 60-minute booking across fall-back is still 60 minutes -- and looks like zero

This pack pins exact duration everywhere: a 60-minute appointment spanning a fall-back transition is 60 real minutes whose start and end render as the identical wall-clock hour, an hour apart.

This is one of the things Scheduling & Availability Core already handles. Bookings and availability that survive timezones, repeating events and daylight saving — without double-booking.

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Is this you?

Treating a booking's duration as nominal -- '60 minutes' meaning 'one hour later on the clock' -- rather than exact elapsed time produces a wrong result the moment a booking spans a DST transition: on a fall-back night, a booking starting at 1:00am and ending 'one hour later' at 2:00am is actually two real hours, because 1:00am-2:00am happens twice; a booking treated as nominal duration silently doubles or halves its real length depending on which direction the transition runs.

Why this one is easy to get wrong

Adding a fixed number of hours to a wall-clock time to get an end time is the natural, simplest way to compute a booking's end -- and it's indistinguishable from correct on every night that isn't a DST transition, which is the overwhelming majority of nights. The RFC's own distinction between exact and nominal duration is a fairly obscure spec detail that most scheduling code never has reason to encounter until a booking happens to span the specific night it matters.

What you get instead

durationMinutes on both a rule and a booking is always real elapsed minutes, computed in the exact representation, never nominal -- a 3-hour availability window starting 23:00 on a US fall-back night ends at 01:00 local, not 02:00, and a 60-minute appointment crossing the boundary is genuinely 60 real minutes whose rendered start and end show the identical wall-clock hour, an hour apart. maxHorizonDays is likewise exact 24-hour days rather than a calendar concept, documented as a one-function change if a product instead wants calendar days in the resource's own zone.

Source: ARCHITECTURE.md 'Duration is EXACT minutes (decided)' — checkable in the pack you receive

How you actually use this

You don’t install a library or wire up an SDK. Your own coding agent builds the code in your project, and you keep it — no runtime dependency on us.

Step 1
Download and unzip
You get a folder: the docs that tell an agent what to build, a starting skeleton, and the test suite that decides when it's done.
Step 2
Open it in Claude Code or Cursor
Point your coding agent at the folder. Nothing to install, no account with us, no API key.
Step 3
Paste one prompt
The pack contains the exact prompt. Paste it as your first message and leave it alone — it works through the build itself, choosing a cheaper or stronger model per task.
Step 4
Run ./verify.sh
One command. It prints a pass or fail for every check. Green means the build is done — the same script we ran to produce the receipt on this page.

Typical build: about 22 minutes of your agent working, mostly unattended. Then you integrate the working module into your app the way you would any code you’d written yourself.

Why you can believe this

3 of 3 runs passed

We ran this pack from an empty folder 3 times and published exactly what happened — every check, the model, the token cost, the wall time. Not a testimonial, and not our opinion: the same verify.sh you run yourself. Read the full receipt →

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