Question: intended timezone convention for options-chain DTE

**Describe the behavior

Options-chain DTE calculations appear to depend on the local timezone of the machine running OpenBB.

For example, the YFinance options-chain provider obtains the exchange timezone:

tz = timezone(underlying.get("exchangeTimezoneName", "UTC"))

However, DTE is calculated using the machine’s local calendar date:

now = datetime.now().date()
dte = (exp - now).days

I found similar local-date calculations in other options-chain providers, so I wanted to confirm the intended cross-provider convention before proposing a code change.

** To reproduce

At the same instant worldwide:

from datetime import datetime, timezone
from pytz import timezone as get_timezone

instant = datetime(
    2026,
    7,
    28,
    1,
    30,
    tzinfo=timezone.utc,
)

exchange_timezone = get_timezone("America/New_York")
machine_timezone = get_timezone("Asia/Tokyo")

exchange_date = instant.astimezone(exchange_timezone).date()
machine_date = instant.astimezone(machine_timezone).date()

expiration = datetime(2026, 7, 31).date()

exchange_dte = (expiration - exchange_date).days
machine_dte = (expiration - machine_date).days

print("Exchange calendar date:", exchange_date)
print("Machine calendar date:", machine_date)
print("DTE using exchange date:", exchange_dte)
print("DTE using machine date:", machine_dte)

Output:

Exchange calendar date: 2026-07-27
Machine calendar date: 2026-07-28
DTE using exchange date: 4
DTE using machine date: 3

The same contract can therefore receive a different DTE depending on the user’s machine timezone.

** Expected behavior / question

What is the intended convention for options-chain DTE across providers?

1. Machine-local date
2. UTC date
3. Exchange-local date
4. A date or DTE supplied directly by the provider

I would be happy to contribute a deterministic regression test and implementation once the intended behavior and scope are confirmed.

** Desktop

• OS: macOS
• Python version: 3.14.4
• Branch: develop

** Additional context

I have not changed the implementation yet because multiple providers appear to use the machine-local date, and changing only YFinance could introduce inconsistent behavior across providers.