Source: https://guthlabs.ai/docs/instruments/jet-lag-planner/
instrument / verified-clean
# Jet Lag Planner
The current ledger marks this instrument verified clean within the source-bound verification corpus.
Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**
## Inspectable records
[01**Overview**Purpose and lifecycle]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## Ledger state
The current ledger marks this instrument verified clean within the source-bound verification corpus.
**Area**: Everyday & Life
**Tranche**: tranche-4
**Evidence ID**: t4-175
**Ledger rows**: 1
No ledger note is attached.
## Review findings
The honest_label appropriately states that this is an educational rule of thumb and not medical or sleep-disorder advice. Before release, define timezones_crossed precisely, add a rounding policy, provide the missing light-exposure logic and constraints, and require baseline sleep information for a true day-by-day schedule.
### Formula and scope findings
- The adjustment formula is underspecified for fractional results: no rounding or schedule-length policy is given when timezones_crossed/1.5 is non-integer.
- The term timezones_crossed is ambiguous: it could mean absolute UTC-offset difference, legal time-zone boundaries crossed, or destination-minus-home offset; daylight-saving changes and the International Date Line are not addressed.
- No formula is provided for the promised light-exposure suggestion.
- The bedtime-shift rule does not define whether eastward means earlier bedtime and westward means later bedtime, nor does it specify how many pre-flight days are available.
- A day-by-day schedule cannot be computed from the listed inputs without a baseline bedtime, wake time, desired sleep window, and schedule start date.
### Unit assumptions
- timezones_crossed is treated as the absolute difference between home and destination UTC offsets, measured in hours; fractional offsets such as 4.5 hours are allowed.
- direction is eastward when the destination UTC offset is greater than the home offset and westward when it is lower.
- For test arithmetic, eastward adjustment is 1 day per crossed time zone and westward adjustment is 1.5 crossed time zones per day.
- The approximately 1-hour daily bedtime shift is treated as exactly 1 hour for testing; eastward means shifting bedtime 1 hour earlier per day and westward means shifting it 1 hour later per day.
- No clinical light-timing recommendation is inferred because the specification supplies no light-exposure formula.
## Boundary hardening
**BREAK_CLAIMED** · SELF_FLAGGED
The arithmetic itself has no division-by-zero trap, but the specification does not define a precise light-exposure algorithm or an unambiguous sign convention for bedtime shifts. Consequently, concrete light timing and consistently signed schedules cannot be generated without additional conventions.
## Errata and corrections
No applied erratum is attached to this unique-name record.
## Inspectable example
4 review vectors are recorded. One source-bound sample is shown below.
````
{
"inputs": {
"home_zone": "America/New_York",
"destination_zone": "Asia/Tokyo",
"travel_date": "2026-04-10",
"home_utc_offset_hours": -5,
"destination_utc_offset_hours": 9,
"direction": "eastward",
"timezones_crossed": 14
},
"expected_outputs": {
"days_to_adjust": 14,
"bedtime_shift_hours_per_day": -1,
"bedtime_shift_direction": "earlier",
"light_exposure": "undetermined_by_spec"
},
"working": "UTC-offset difference = 9 - (-5) = 14 hours. Eastward rate = 1 timezone/day. Days to adjust = 14 / 1 = 14 days. Bedtime shift = 1 hour/day earlier, represented as -1 hour/day."
}
````
## Related workflows
No source-defined multi-instrument workflow membership is recorded.
## Sources and evidence
These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.
- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`
- `evidence-tranche4/tranche4-results.json`
- `BOUNDARY_HAZARD_CATALOG.json`