improve(internet-identity): add derivationOrigin anti-pattern pitfall

[marc0olo]

Summary

• Adds mistake #7: icp0.io and ic0.app produce the same principal — II auto-rewrites during delegation. Adding derivationOrigin or ii-alternative-origins for this breaks auth. Different principal = different passkey/device.
• Adds eval for the domain equivalence diagnostic scenario

Addresses #136 (F3).

Eval results

Different principal after login on icp0.io vs ic0.app

Behavior	With skill	Without skill
Explains II auto-rewrites icp0.io to ic0.app	✅	❌
Advises NOT to add derivationOrigin	✅	❌
Suggests different passkey/device as cause	✅	❌

With skill: 3/3 — Without skill: 0/3

Without the skill, the agent recommends exactly the anti-pattern: adding derivationOrigin and ii-alternative-origins, which broke authentication in the real-world session that surfaced this issue.

[github-actions]

Skill Validation Report

Validating skill: /home/runner/work/icskills/icskills/skills/internet-identity

Structure

• Pass: SKILL.md found

Frontmatter

• Pass: name: "internet-identity" (valid)
• Pass: description: (323 chars)
• Pass: license: "Apache-2.0"
• Pass: compatibility: (31 chars)
• Pass: metadata: (2 entries)

Markdown

• Pass: no unclosed code fences found

Tokens

File	Tokens
SKILL.md body	1,687
Total	1,687

Content Analysis

Metric	Value
Word count	994
Code block ratio	0.32
Imperative ratio	0.12
Information density	0.22
Instruction specificity	1.00
Sections	8
List items	9
Code blocks	2

Contamination Analysis

Metric	Value
Contamination level	low
Contamination score	0.03
Primary language category	config
Scope breadth	2

• Warning: Language mismatch: javascript (1 category differ from primary)

Result: passed

Project Checks

✓ Project checks passed for 1 skills (0 warnings)