Update Skills & Instructions

When a major repository learning is discovered — a recurring pattern, a non-obvious pitfall, a crucial architectural constraint, or domain knowledge that would save future sessions significant time — capture it as a skill or instruction so it persists across sessions.

When to Use

• The user explicitly says "learn!" or asks to capture a learning
• You discover a significant pattern or constraint that cost meaningful debugging time
• You identify reusable domain knowledge that isn't documented anywhere in the repo
• A correction from the user reveals a general principle worth preserving

Decision: Skill vs Instruction vs Learning

Add a learning to an existing instruction when:

• The insight is small (1-4 sentences) and fits naturally into an existing instruction file
• It refines or extends an existing guideline
• Follow the pattern in .github/instructions/learnings.instructions.md

Create or update a skill (.github/skills/{name}/SKILL.md or .agents/skills/{name}/SKILL.md) when:

• The knowledge is substantial (multi-step procedure, detailed guidelines, or rich examples)
• It covers a distinct domain area (e.g., "how to debug X", "patterns for Y")
• Future sessions should be able to invoke it by name

Create or update an instruction (.github/instructions/{name}.instructions.md) when:

• The rule should apply automatically based on file patterns (applyTo) or globally
• It's a coding convention, architectural constraint, or process rule
• It doesn't need to be invoked on demand

Procedure

1. Identify the Learning

Reflect on what went wrong or what was discovered:

• What was the problem or unexpected behavior?
• Why was it a problem? (root cause, not symptoms)
• How was it fixed or what's the correct approach?
• Can it be generalized beyond this specific instance?

2. Check for Existing Files

Before creating new files, search for existing skills and instructions that might be the right home:

# Check existing skills
ls .github/skills/ .agents/skills/ 2>/dev/null

# Check existing instructions
ls .github/instructions/ 2>/dev/null

# Search for related content
grep -r "related-keyword" .github/skills/ .github/instructions/ .agents/skills/

3a. Add to Existing File

If an appropriate file exists, add the learning to its ## Learnings section (create the section if it doesn't exist). Each learning should be 1-4 sentences.

3b. Create a New Skill

If the knowledge warrants a standalone skill:

1. Choose the location:
   • .github/skills/{name}/SKILL.md for project-level skills (committed to repo)
   • .agents/skills/{name}/SKILL.md for agent-specific skills
2. Create the directory and SKILL.md with frontmatter:

---
name: {skill-name}
description: {One-line description of when and why to use this skill.}
---

# {Skill Title}

{Body with guidelines, procedures, examples, and learnings.}

3. The name field must match the parent folder name exactly.
4. Include concrete examples — skills with examples are far more useful than abstract rules.

3c. Create a New Instruction

If the knowledge should apply automatically:

---
description: {When these instructions should be loaded}
applyTo: '{glob pattern}' # optional — auto-load when matching files are attached
---

{Content of the instruction.}

4. Quality Checks

Before saving:

• Is the learning general enough to help future sessions, not just this one?
• Is it specific enough to be actionable, not just a vague principle?
• Does it include a concrete example of right vs wrong?
• Does it avoid duplicating knowledge already captured elsewhere?
• Is the description clear enough that the agent will know when to invoke/apply it?

5. Inform the User

After creating or updating the file:

• Summarize what was captured and where
• Explain why this location was chosen
• Note if any existing content was updated vs new content created