ml4t-data-leakage SKILL.md skillA
ml4t-data-leakage from ml4t/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add ml4t/skills/ml4t-data-leakage@git:20260901.c415df0Pins git:20260901.c415df0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- ml4t/skills
- Path
concepts/data-leakage/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260901.c415df0, committed Sep 1, 2026
- First version recorded
- May 28, 2026
- Size
- 4,036 bytes
- Repository stars
- 41
- License
- Apache-2.0
Prevent train-test contamination, target leakage, and temporal leakage. Use when splitting data, fitting preprocessors, or engineering features for time-series ML.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Data Leakage Leakage lets test-set information influence training, producing models that look good in development but fail in production. ## The Problem Three distinct failure modes inflate backtest performance: 1. **Target leakage** - features computed from the target variable (e.g., future returns embedded in a "sentiment score" that was derived from price changes). 2. **Train-test contamination** - fitting a scaler, encoder, or selector on the full dataset before splitting, so test statistics leak into training transforms. 3. **Temporal leakage** - using future data in features (overlaps with lookahead bias, but here the mechanism is the train/test split itself, not the feature formula). A pipeline that fits a `StandardScaler` on the full matrix before splitting commonly inflates Sharpe by 0.2-0.5 on daily data. The model learns the test set's distribution. ## The Pattern ### WRONG ```python from sklearn.preprocessing import StandardScaler from sklearn.linear_model import Ridge scaler = StandardScaler() X_scaled = scaler.fit_transform(X) # fit on ALL data (leaks test stats) X_train, X_test = X_scaled[:split], X_scaled[split:] …
Read the whole file at its exact version.
How to install
mdr add ml4t/skills/ml4t-data-leakage@sha256:391956cb6f95a9eaThe line at the top of this page pins the label git:20260901.c415df0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_m2ftq7spsgyrdwkz)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between May 28, 2026 and Sep 1, 2026, about one every 96 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260901.c415df0 latest | 2026-09-01 | c415df0 | 4,036 B | A | view · diff |
| git:20260528.303089e | 2026-05-28 | 303089e | 4,046 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 (4036 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 · 41 stars · license Apache-2.0 · pushed 2026-11-08 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_m2ftq7spsgyrdwkz GET https://markdownregistry.com/api/v1/resolve?ref=ml4t/skills/ml4t-data-leakage GET https://markdownregistry.com/api/v1/blob/391956cb6f95a9eaf3d72ea4289290e118500ce2b17878f68dcee7ba01e087ca
Your AI assistant 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.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.