my-skill

description: "Create new Cursor skills following the Agent Skills spec. Use when: (1) creating automation for repeatable tasks, (2) documenting team patterns, (3) packaging domain knowledge for reuse. Guides through skill qualification, structure, frontmatter, content organization, and validation." tags: [skill-authoring, automation, documentation]

Create New Skill

When to Use

• Creating automation for repeatable tasks
• Documenting team patterns and workflows
• Packaging domain knowledge for reuse
• Building new skills following the Agent Skills spec

Skill Structure (Agent Skills Spec)

Based on the Agent Skills specification. See references/agent-skills-spec.md for the full spec.

Each skill is a folder containing a SKILL.md file:

skill-name/
├── SKILL.md           # Required - main skill file
├── scripts/           # Optional - executable helpers
├── references/        # Optional - reference docs
└── assets/            # Optional - templates, images, data files

Frontmatter

Example:

---
name: my-skill
description: "Does X and Y. Use when: (1) scenario A, (2) scenario B."
tags: [workflow, git]
metadata:
  author: orshalev
  version: "1.0"
---

Progressive Disclosure (from spec)

1. Metadata (~100 tokens): name + description loaded at startup for ALL skills
2. Instructions (<5000 tokens): full SKILL.md body loaded when skill activates
3. Resources (on demand): files in scripts/, references/, assets/ loaded only when needed

Keep SKILL.md under 500 lines. Move detailed reference material to separate files.

⚠️ Obsolete fields: alwaysApply, globs - DO NOT USE in skills

0. Skill Qualification

Before writing a skill, verify it’s needed:

• Is the task repeatable across features or teams?
• Does the task require specific domain knowledge?
• Are there already related skills that offer reusable structure?

If YES to any → proceed. If NO → use inline prompt or comment instead.

1. Overview (# Why?)

This skill ensures new Cursor skills are created with adequate context by referencing existing ones. It guides the agent to reuse working patterns, enforce domain-specific expectations, and apply context augmentation for stateless correctness.

2. Requirements (# What?)

• Reference at least 2 similar rules for structure/patterns.
• Analyze 5-10 real codebase implementations to identify gaps and patterns.
• Use the full 6-part task rule structure with progressive disclosure.
• Include domain-specific sections when needed (types, keys, state, flags, UI).
• Apply conditional language to distinguish defaults from alternatives.
• Provide testing scaffold, naming conventions, and pitfalls.
• Assess success rate against real implementations (target 90%+ coverage).
• Clarify file triggers with globs and explain alwaysApply.

3. Progress Tracker

• ✅ Find 2 similar existing rules
• ✅ Analyze real codebase implementations
• ✅ Identify patterns and gaps systematically
• ✅ Draft metadata and description
• ✅ Write core structure with progressive disclosure
• ✅ Add domain-specific sections (type, naming, flags)
• ✅ Apply conditional language for alternatives
• ✅ Validate rule completeness and success rate

4. Implementation Plan

Phase 1: Research

1. Search existing skills and rules for similar patterns:

   • Local skills: .cursor/skills/*/SKILL.md
   • Personal skills: .cursor/skills/personal/*/SKILL.md
   • Community catalog: .cursor/skills/community/catalog.json (if linked — see examine-skills)
   • Legacy rules: .cursor/rules/**.mdc

2. Prioritize similar:

   • Domains (state, services, analytics, feature flags)
   • Trigger files (globs), structure, or behavior

3. Copy excerpts or summarize styles:

   Similar Rule Summary

   • Rule: @persistent_state_add_property.mdc

     • Patterns: Type-specific encode/decode, Behavior test scaffold
     • Gotchas: Forgetting key naming and triple mapping

   • Rule: @assignments_add_experiment_group.mdc

     • Patterns: Feature flag, test matrix, state-to-UI linkage

Phase 1A: Download Supporting Assets (OPTIONAL)

If the user provides Google Drive URLs for screenshots, PDFs, or other assets, download them and store alongside the skill for future reference.

# One-time setup (see scripts/gdrive_cli/README.md for credentials.json)
cd scripts/gdrive_cli
uv run gdrive auth

# Download asset into the new skill's references folder
uv run gdrive download "URL" -o "skills/<skill-name>/references"
# Use --format when exporting Docs/Sheets/Slides (e.g. --format pdf or --format md)

Reference the downloaded files in the "Context & References" section.

Phase 1B: Real Codebase Analysis (CRITICAL)

3B. Analyze actual implementations to identify gaps and patterns:

# Find 5-10 real implementation files, not just examples
find . -name "*ExperimentGroup*.swift" | head -10
find . -name "*Reducer*.swift" | head -10
find . -name "*PresentationState*.swift" | head -10

3C. Systematic Gap Analysis:

• What patterns appear in 70%+ of files but aren't in current rules?
• What advanced patterns exist for complex cases?
• What alternative approaches do experienced developers use?
• What architecture mistakes do files reveal?

3D. Categorize findings:

• Standard Requirements: Must always be included
• Preferred Alternatives: Recommend first, show alternatives
• Optional Additions: Use when specific needs arise
• Advanced Patterns: For complex cases only

Phase 2: Define Rule Header

4. Set:

   • description: What this rule automates or enforces
   • globs: Pattern like **/PersistentState*.swift (AVOID – see note below)
   • alwaysApply: Always false. Only tech leads are allowed to choose otherwise.

   [!IMPORTANT] About File Triggers:

   • Most rules should be manually triggered by tagging (@rule_name).
   • Avoid using globs unless absolutely necessary.
   • Rules with extensive instructions (>500 lines) should NEVER auto-apply.
   • Auto-applying can consume significant context window and interfere with routine edits.

Phase 3: Write Rule Content with Progressive Disclosure

5. Include these standard sections:

Overview

Explain the problem or context driving this rule.

Requirements

Checklist of outcomes or constraints.

Progress Tracker

Step-by-step visual indicator.

Implementation Plan

Organize by phases. Use imperative markdown bullets. CRITICAL: Use progressive disclosure - show DEFAULT patterns first, then alternatives.

Context & References

List any:

• @file.swift or @existing-rule.mdc
• APIs or data contracts
• Screenshots: <!-- Screenshot: mdc:/assets/example.png -->

Constraints & Done

What NOT to change. Completion criteria.

5B. Apply Progressive Disclosure Strategy:

• Show common/default patterns prominently
• Mark alternatives clearly as such
• Use conditional guidance: "Use when...", "Optional for...", "Required when..."
• Avoid overwhelming beginners with advanced patterns upfront

Phase 3B: Progressive Disclosure Principles

[!CRITICAL] Always structure information from common to rare:

1. Lead with defaults (80 % cases)

   • Show the standard approach prominently.
   • Mark with // ✅ PREFERRED: or ### ✅ Common Case (DEFAULT):.

2. Present alternatives conditionally

   • Use // ⚠️ ALTERNATIVE: for less common approaches.
   • Always explain WHEN to use: "only when [specific condition]".
   • Consider commenting out alternative code blocks with /* */.

3. Critical user decisions

   • Mark with [!IMPORTANT] Ask the user before choosing.
   • Never assume configuration choices (e.g., "should run in China", "should run on iPad").
   • List options clearly for user selection.

4. Avoid encouraging shared resource modifications

   • Don't encourage adding to shared enums (e.g., CommonUserAffectedReason).
   • Frame as: "only when multiple use cases arise AND with explicit approval".

Phase 3C: Quality Gate & Validation Checklist

Before finalizing the rule, run these mandatory checks to avoid the most common author-ing mistakes noticed in past reviews:

1. PR/Commit Accuracy

   • Verify the PR description and commit body mention only the rules/files actually added or changed.
   • Remove stale references to rules that were NOT part of the diff.

2. Reference Integrity

   • For any referenced code file that might be deleted in the future, paste a minimal self-contained snippet inside the rule rather than only the file path.

3. User-Driven Decisions

   • Replace any domain-specific default assumption (e.g. runInChina, reasonsAffectedUser) with // TODO(ask-user) placeholders that cause a compile-time error (#error("Ask user") in Swift) until the user provides explicit instructions.

4. Naming & Enum Accuracy

   • Double-check domain names against the source code (e.g. CommonUserAffectedReason vs UserAffectedReason).
   • Ensure property names in examples conform to actual conventions (alphabetical order, suffixes, etc.).

5. Anti-Pattern Sweep

   • Search the draft for known anti-patterns such as loadOptional(.key) ?? defaultValue and replace with the canonical API (load(.key, default:)).

6. Context Budget

   • Keep examples concise (<20 lines each) and remove super-fluous design-specific code that does not affect the logical flow.

7. Checklist Completion

   • Confirm all items in this Quality Gate are ticked before marking the rule as complete.

Phase 4: Add Domain-Specific Sections with Conditional Language

6. Structure domain-specific guidance using progressive disclosure patterns:

   Domain-specific sections guide users through different implementation paths based on their specific needs. The key is showing the most common pattern first, then progressively revealing alternatives for more complex scenarios.

   Core Principles:

   • Lead with the DEFAULT/common case (80% usage)
   • Mark alternatives clearly with conditions
   • Use visual markers (✅, ⚠️) for quick scanning
   • Include inline comments for decision points

   Structural Patterns to Use:

   ## [Number]. [Domain-Specific Topic]
   
   ### ✅ [Common Case] (DEFAULT):
   [Code/guidance for the standard approach]
   
   ### ✅ [Alternative Case] (when [specific condition]):
   [Code/guidance for this variant]
   
   ### ⚠️ [Rare/Advanced Case] (only when [edge condition]):
   [Code/guidance for exceptional situations]
   

   Example from Persistent State:

   ## 5. Type-Specific Handling
   
   ### ✅ Dates, Bools, Ints:
   - Encode as-is using `loadOptional(.key)`
   - Use `StoringBehavior<Date?>` for optional dates
   
   ### ✅ Enums:
   [Enum pattern with .Stored wrapper]
   
   ### ✅ Arrays & Dictionaries:
   - Encode directly if elements are primitives
   - For custom types, convert to `.Stored` then encode
   

   Decision Points Pattern:

   // ✅ PREFERRED: Use existing CommonUserAffectedReason when possible.
   static func reasonsAffectedUser(params: AppRDXParams) -> [String] {
     return CommonUserAffectedReason.getReasonStrings(...)
   }
   
   // ⚠️ ALTERNATIVE: Create custom logic only when CommonUserAffectedReason insufficient.
   /*
   static func reasonsAffectedUser(params: AppRDXParams) -> [String] {
     // Custom implementation
   }
   */
   

   Critical User Decisions:

   [!IMPORTANT] Ask the user before choosing.
   - Option A: Use when [specific condition]
   - Option B: Use when [different condition]
   

   Optional Sections Pattern:

   ### Phase 2B: Add Static Helpers (OPTIONAL - for complex eligibility):
   // Only add when business logic is reused across multiple files
   

7. If defining keys/constants:

Naming Conventions

• Specify specific format: someStorageKey_MM_YY, someExperimentGroupName_MM_YYYY, SomeProtocolsIMPL
• Must describe purpose and have version suffix

8. If crossing services/state/UI:

Data Flow Touchpoints

• Update: stateModel → manager → UI bindings
• Integration points: list all required files

9. If using feature flags:

Experiment Handling

• Describe expected gating: if (featureGate.isEnabled()) { ... }
• Include default behavior and test matrix

10. If UI is affected:

UI Notes

• Link design spec or include: <!-- Screenshot: mdc:/assets/foo.png -->

11. If common mistakes exist:

Common Gotchas

• Example: "Don’t forget to map all 3 key paths"

7. Common Rule Writing Pitfalls to Avoid

DO NOT:

• Set alwaysApply: true (unless you're a tech lead with specific reasons).
• Create rules >500 lines that auto-apply via globs.
• Assume user preferences (always use [!IMPORTANT] for decisions).
• Encourage modifications to shared resources without approval.
• Include overly specific design details that change frequently.
• Provide instructions for actions agents cannot perform.
• Use incorrect terminology without verifying in codebase.

DO:

• Default to manual triggering with alwaysApply: false.
• Use progressive disclosure (common → alternative → advanced).
• Mark critical decisions for user input.
• Focus on patterns and references rather than rigid implementations.
• Acknowledge platform limitations explicitly.
• Verify all names, properties, and conventions from actual code.

Phase 5: Validate and Assess Success Rate

12. Match structure to @persistent_state_add_property and @assignments_add_experiment_group
13. Ensure headings, checkboxes, codeblocks follow Lightricks standards
14. Check all provided code is minimal, real, and copyable

Phase 5B: Success Rate Assessment

15. Test rule effectiveness against real codebase files:

• Would this rule successfully guide creation of 5-10 analyzed files?
• What percentage of common use cases are covered?
• What percentage of complex use cases have guidance?
• Estimate: Simple cases ___%, Medium cases ___%, Complex cases ___%

16. Identify remaining gaps:

• What patterns are still missing?
• What would fail with current rule guidance?
• What requires expert knowledge not captured?

Phase 5C: Iteration and User Feedback

17. Be prepared to iterate when users provide corrections:

• Architecture mistakes happen - user corrections are valuable
• Update patterns based on real usage experience
• Adjust progressive disclosure based on feedback
• Don't override existing requirements - add alternatives instead

5. Context & References

• Referenced rules:

  • @persistent_state_add_property.mdc
  • @assignments_add_experiment_group.mdc - Recently updated using this methodology

• Successful Case Study: Experiment Group Rule Update

  • Analyzed 10 real ExperimentGroup files systematically
  • Identified 10 critical gaps through codebase analysis
  • Applied progressive disclosure strategy (30% → 90% success rate)
  • Used conditional language to avoid breaking existing patterns
  • Integrated user feedback to correct architecture mistakes

• Cursor Docs: Rule triggers and types

6. Constraints & Done

• DO NOT guess APIs or file paths — use existing ones.
• DO NOT write rules without researching prior art.
• DO NOT override common patterns — add alternatives instead.
• DO NOT force advanced patterns — use progressive disclosure.
• ✅ Quality Gate checklist completed
• ✅ All 6 core sections written
• ✅ Real codebase analysis completed (5-10 files)
• ✅ Progressive disclosure applied (defaults → alternatives → advanced)
• ✅ Conditional language used (PREFERRED vs ALTERNATIVE)
• ✅ Domain scaffolds added (types, keys, UI, flags)
• ✅ Success rate assessed (target 90%+ coverage)
• ✅ Refs to prior rules included
• ✅ Globs and triggering logic defined

Phase 5D: Skill Validation Checklist

Before finalizing, verify compliance with Agent Skills spec:

• Folder structure: {skill-name}/SKILL.md (not a standalone file)
• name field in frontmatter matches folder name (lowercase, hyphens only, 1-64 chars)
• description field clearly describes what the skill does and when to use it (max 1024 chars)
• No obsolete fields (alwaysApply, globs) in frontmatter
• SKILL.md under 500 lines — move details to references/
• Optional: tags for catalog discovery
• Optional: references/ folder for supporting docs
• Optional: scripts/ folder for automation helpers

Additional quality checks:

• Progressive disclosure applied (defaults → alternatives)
• User decisions marked with [!IMPORTANT]
• All terminology verified against codebase
• Platform limitations acknowledged