ml4t-calendar-ops skillA
ml4t-calendar-ops is agent-read markdown (skill) from ml4t/skills: Trading calendar awareness for correct date alignment and rolling windows. Use when aligning data across markets or computing holiday-aware windows..
Indexed from public GitHub and served as immutable, content-addressed versions. Install it pinned to an exact SHA-256 with the mdr CLI, and every file is verified against the hash recorded here before it reaches your agent. The deterministic audit below grades the latest version, and the same file always earns the same grade.
What the file says
# Calendar Operations
Using calendar days instead of trading days for a 20-day rolling window includes weekends and holidays, producing a window that covers 28 calendar days but only 20 observations - silently misaligning your features with your labels.
## The Problem
Markets are closed on weekends and holidays. A "20-day momentum" signal should use 20 trading days (~4 weeks), not 20 calendar days (~2.8 weeks). When you mix calendar-day math with trading-day data, rolling windows span wrong periods, cross-market joins misalign (NYSE is closed on Presidents Day but LSE is open), and date arithmetic produces gaps your model interprets as missing data. These errors are invisible until you compare strategy behavior across markets or time zones.
## The Pattern
### WRONG
```python
import polars as pl
from datetime import timedelta
# Calendar days for rolling window - includes weekends, holidays
df = df.with_columns(
momentum=pl.col("close") / pl.col("close").shift(20) - 1 # shift(20) = 20 rows
)
# If data has gaps (holidays), shift(20) is NOT 20 trading days - it skips over them unevenly
# Date arithmetic for label alignment
df = df.with_columns(
…Read the whole file at its exact version.
How to install
mdr add ml4t/skills/ml4t-calendar-ops@git:20260901.c415df0mdr add ml4t/skills/ml4t-calendar-ops@sha256:8e463698e1ccb41ePin to a label to follow the author's releases, or to a sha256 to freeze the exact bytes forever. Either way the resolved hash is written to mdr.lock, and mdr install reproduces it on any machine.
[](https://markdownregistry.com/a/art_xri2w3jywyryamyb)
1 badge views in 30 days
Versions
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260901.c415df0 latest | 2026-09-01 | c415df0 | 4,659 B | A | view · diff |
| git:20260528.303089e | 2026-05-28 | 303089e | 4,675 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (4659 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
ml4t/skills · 19 stars · license Apache-2.0 · pushed 2026-09-24 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_xri2w3jywyryamyb GET https://markdownregistry.com/api/v1/resolve?ref=ml4t/skills/ml4t-calendar-ops GET https://markdownregistry.com/api/v1/blob/8e463698e1ccb41edcac3e9164fac409efc3e6a8bd79222bdfc58b7b6cfb467f
Your agent does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.