Creating Copilot Instructions

Use this skill when the goal is to package stable rules for GitHub Copilot instead of writing one-off guidance in chat. It helps turn repository conventions into clean instruction files that are easy to install, reason about, and maintain.

When to Use

Use this skill when the user asks for things like:

• "create a repo-wide Copilot instruction file"
• "write a .instructions.md file for these tests"
• "choose the right applyTo pattern"
• "turn our coding rules into installable instructions"
• "fix an instruction file that is too broad or too vague"

Typical scenarios:

• first-time setup of copilot-instructions.md
• adding targeted guidance for a folder, language, or test type
• splitting an overgrown instruction file into smaller units
• preparing public examples for a team repository or a shared collection

What Good Looks Like

A strong instruction contribution usually includes:

• the right instruction type for the job: repo-wide or scoped
• a narrow, predictable scope
• short declarative rules with a reason when the rule is not obvious
• examples only where they materially improve compliance
• no workflow logic, no agent personality, and no prompt-specific scripting

Instruction Design Rules

• Rules over essays - prefer short, stable guidance that survives multiple tasks.
• Scope first - the applyTo pattern is part of the design, not an afterthought.
• Reason when needed - if a rule is surprising, explain the consequence in the same bullet.
• Examples beat abstraction - include a preferred and avoided example for tricky patterns.
• Context is expensive - avoid loading broad instructions that repeat what tools already enforce.

Workflow

Phase 0: Frame the request

Clarify or infer:

• whether the user needs repo-wide guidance or scoped instructions
• who will install the file: one user, a team, or a public collection
• which files or folders must be affected
• what conventions are stable enough to encode as rules

Phase 1: Study the source material

Before drafting:

• inspect existing instructions, README notes, and representative source files
• separate lint or formatter-enforced behavior from guidance that still needs human judgment
• collect only durable conventions; avoid temporary migration notes unless explicitly requested

Phase 2: Choose the file shape

Use this decision rule:

• create copilot-instructions.md when the rules apply to nearly every task in the repository
• create *.instructions.md when the rules apply to a clear file pattern, directory, or workflow boundary
• split files when one audience would otherwise inherit unrelated rules

Phase 3: Draft the instruction file

For scoped instruction files:

• choose a descriptive filename in kebab case
• write frontmatter with description, applyTo, title, and name when helpful
• keep each rule compact and testable
• add examples only for non-obvious conventions

For repo-wide instruction files:

• describe architecture, stack, folder responsibilities, commands, and non-obvious conventions
• organize by headings so Copilot can find the right rule quickly
• keep it opinionated enough to be useful but not so exhaustive that it becomes background noise

Phase 4: Create the artifact bundle

Always prepare:

• the main instruction file
• a short installation note or target path
• at least one reference template or example when the instruction is meant to be reused
• a brief summary of why the scope and file type were chosen

Use these supporting resources:

• ./resources/copilot-instructions.template.md
• ./resources/custom-instructions.template.instructions.md
• ./resources/copilot-instructions.example.md
• ./resources/custom-instructions.example.instructions.md

Phase 5: Validate before handoff

Check the final result against ./resources/instructions-quality-checklist.md.

Pay extra attention to:

• applyTo being narrow enough to avoid accidental always-on context
• rules being declarative, not step-by-step workflows
• examples matching the claimed rule
• no duplication of agent behavior, prompt workflow, or skill instructions

Common Failure Modes

• using applyTo: '**' for advice that only matters in one part of the repo
• turning the file into a tutorial instead of a rule set
• copying linter or formatter defaults instead of encoding missing conventions
• mixing multiple unrelated audiences into one instruction file
• writing rules without enough context for Copilot to understand why they matter

Resource Map

• ./resources/copilot-instructions.template.md - repo-wide starting point for a project constitution
• ./resources/custom-instructions.template.instructions.md - scoped instruction template with frontmatter
• ./resources/copilot-instructions.example.md - worked repo-level example for a test automation repository
• ./resources/custom-instructions.example.instructions.md - worked scoped example with concrete rules
• ./resources/instructions-quality-checklist.md - final review checklist before shipping

Definition of Done

A task using this skill is complete when:

• the chosen instruction type matches the actual scope
• the file is install-ready and placed in the right target location
• the rules are concise, durable, and non-duplicative
• supporting template or example material exists when the artifact is meant for reuse
• the final result passes the quality checklist without obvious ambiguity