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nainishshafinainishshafi/developer-productivity-skills/.github/skills/powershell-writer/SKILL.md

powershell-writer

Skill1 starsChanged 4 days agoMITView on GitHub

Writes idiomatic, high-performance, and secure PowerShell scripts, modules, and automation workflows (PowerShell 7.4+ LTS & Windows PowerShell 5.1). Covers advanced functions ([CmdletBinding]), approved verbs, object pipeline streaming, error handling with Set-StrictMode, Pester v5 testing, PSScriptAnalyzer rules, and parallel concurrency. Use when asked to "write powershell", "powershell script", "create powershell module", "powershell-writer", "ps1 script", "pester test", or "powershell automation".

1 other project uses a version of this.

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The file

We split this skill into the rules it gives an agent

3 rules. About 0 are common, 0 are distinctive, and 3 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈0

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 3

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    Prefer simple .ps1 scripts for linear orchestration (< 150 lines).

    line 27
  2. Very specific:

    Never use Invoke-Expression (iex).

    line 29
  3. Very specific:

    Always validate manifests using Test-ModuleManifest before shipping.

    line 30

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

PowerShell Writer

Staff-level guidance for authoring production-grade PowerShell scripts, advanced functions, and enterprise modules across cross-platform environments (Windows, Linux, macOS).

When to Use This Skill

  • Writing standalone automation scripts (.ps1) or reusable modules (.psm1 / .psd1).
  • Implementing advanced cmdlets with [CmdletBinding()], parameter validation, and pipeline streaming (begin/process/end).
  • Enforcing defensive error handling with $ErrorActionPreference = 'Stop', try/catch, and Set-StrictMode.
  • Eliminating performance bottlenecks like the $O(N^2)$ array append antipattern ($arr += $item).
  • Multi-threading and background tasks using ForEach-Object -Parallel, Start-ThreadJob, or Runspaces.
  • Authoring unit tests with Pester v5 and linting with PSScriptAnalyzer.

Architectural Philosophy: Guidance Over Dogmatism

PowerShell is an object-oriented shell and automation engine. Heuristics guide design:

  • Prefer simple .ps1 scripts for linear orchestration (< 150 lines); use Modules (.psm1) when distributing 5+ reusable cmdlets.
  • Emit structured [PSCustomObject] rather than raw strings or bloated custom C# class hierarchies.
  • Never use Invoke-Expression (iex); pass arrays or use the call operator (&).
  • Always validate manifests using Test-ModuleManifest before shipping.

Core Knowledge Modules

Load the relevant module based on your task:

DomainDescriptionModule File
Core & Cmdlet Design[CmdletBinding()], approved verbs, pipeline binding, parameter validationCmdlet Design
Error Handling$ErrorActionPreference = 'Stop', Set-StrictMode, try/catch, $LASTEXITCODEError Handling
Anti-Bloat & PragmatismDecision matrix, over-engineering self-checks, avoiding $O(N^2)$ array trapsAnti-Bloat Guidelines
Pipeline & SplattingStreaming, [PSCustomObject], calculated properties, hashtable splatting (@params)Pipeline & Objects
Data & REST APIsInvoke-RestMethod, JSON depth limits, CSV/XML, native CLI argument quotingData & REST APIs
Concurrency & JobsForEach-Object -Parallel, thread-safe collections, Start-ThreadJob, RunspacesConcurrency & Parallelism
Module ArchitectureProfessional directory layout, .psm1, .psd1 manifests, Export-ModuleMemberModule Architecture
Security & Hardeningiex ban, SecureString, SecretManagement, ExecutionPolicy, CLMSecurity & Hardening
Testing & QualityPester v5 test patterns (Discovery vs Run), mocks, PSScriptAnalyzer rulesTesting with Pester v5

References

  • PowerShell Writer Reference Guide — Comprehensive architectural and operational reference.
  • Code Reviewer — Multi-language senior code review skill.
  • API Security — Universal API security and authentication audit.
  • Detect Overengineering — Anti-bloat heuristics and YAGNI auditing.

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