Shadow Mode Validation

Q: What is a Claude Code skill and how does the Shadow Mode Validation skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Shadow Mode Validation is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Engineering · Sub-category: devops · Last updated: 2026-07-15

Design know-how for shadow-mode validation — running a candidate decision mechanism (typically an LLM judgment) in observe-only parallel with the live path, recording what it WOULD have decided per event, and letting the accumulated record decide enforcement, in the style of ADR-0076's skill-selection shadow instrument. Use when an unvalidated stochastic mechanism is about to replace or filter a live behavior (a one-way door for output quality), when a selector/classifier/gate has no published reliability evidence for the model class in play, or when designing the isolation, kill-switch, and exit criteria for a shadow deployment. NOT for aggregate readings over stored state (that is read-only-instruments / ADR-0071), NOT for the audit-log record schema itself (that is replayable-audit-logs / ADR-0075 — a shadow log IS one of those logs), and NOT a substitute for unit tests — shadow mode validates decision quality in production traffic, not code correctness.

Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

Shadow mode runs a candidate decision mechanism alongside the live path, records its would-be decision per event, and changes nothing. The live behavior stays exactly as it was; the only output is an append-only record of "here is what the new mechanism would have done." Enforcement — actually letting the mechanism steer behavior — is a separate, later decision made from the accumulated record. Canonical example: core/skill_selection.py (ADR-0076) — a pass-1 LLM skill-applicability selection observed for 2–4 weeks before any change to system-prompt injection.

What this skill does

Shadow Mode Validation is a community-contributed Claude Code skill in the devops sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/shadow-mode-validation/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when an unvalidated stochastic mechanism is about to replace or filter a live behavior (a one-way door for output quality), when a selector/classifier/gate has no published reliability evidence for the model class in play, or when designing the isolation, kill-switch, and exit criteria for a shadow deployment. NOT for aggregate readings over stored state (that is read-only-instruments / ADR-0071), NOT for the audit-log record schema itself (that is replayable-audit-logs / ADR-0075 — a shadow log IS one of those logs), and NOT a substitute for unit tests — shadow mode validates decision quality in production traffic, not code correctness.

Who uses this skill

The Shadow Mode Validation Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 158,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/shadow-mode-validation
curl -L https://claudskills.com/skills/shadow-mode-validation/SKILL.md \
  -o ~/.claude/skills/shadow-mode-validation/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/shadow-mode-validation/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/shadow-mode-validation/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\shadow-mode-validation\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Shadow Mode Validation Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/shadow-mode-validation/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the Shadow Mode Validation skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the Shadow Mode Validation skill?

Use Shadow Mode Validation when your Claude Code task falls under the Engineering category — specifically in the devops area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Shadow Mode Validation" or describe the task and let Claude pick). Browse related skills at /category/engineering/.

What is a Claude Code skill and how does the Shadow Mode Validation skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Shadow Mode Validation is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/shimo4228/contemplative-agent/blob/HEAD/.claude/skills/shadow-mode-validation/SKILL.md
License: MIT
Author: shimo4228
Website: https://doi.org/10.5281/zenodo.19212118

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

shimo4228. (2026). Shadow Mode Validation [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/shadow-mode-validation/

BibTeX

@misc{shadow-mode-validation-2026,
  author    = {shimo4228},
  title     = {Shadow Mode Validation [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/shadow-mode-validation/}
}

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Badge

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Security scan

Grade A · scanned 2026-07-23 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
✓ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/shadow-mode-validation/#security)

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Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills. · What's New · Install guide · About · llms.txt

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