feat!: Refactor to PS 7.6 module architecture with automated Pester tests

Modernize LsiGitCheckout from a monolithic PS 5.1 script to a PS 7.6 LTS
module architecture, enabling automated testing and cleaner maintainability.

- Split LsiGitCheckout.ps1 (2746 lines) into entry point (~230 lines) +
  LsiGitCheckout.psm1 module (2522 lines) + LsiGitCheckout.psd1 manifest
- Add Pester 5.x unit tests for 10 pure/near-pure functions
- Add Pester 5.x integration tests covering all 16 test configs (DryRun)
- Upgrade #Requires to PowerShell 7.6 LTS, use null-coalescing operators
- Add CLAUDE.md project context (evolved from claude/wonderful-boyd branch)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: AndreaV-Lsi

.gitignore

@@ -22,8 +22,6 @@ $RECYCLE.BIN/
 
 # PowerShell specific
 *.pssproj
-*.psm1
-*.psd1
 *.ps1xml
 
 # Visual Studio Code

CHANGELOG.md

@@ -5,6 +5,21 @@ All notable changes to LsiGitCheckout will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [8.0.0] - 2026-03-20
+
+### Changed
+- **BREAKING**: Requires PowerShell 7.6 LTS or later (previously 5.1). PowerShell 7.6 installs side-by-side with Windows PowerShell 5.1.
+- Refactored monolithic script into module architecture: `LsiGitCheckout.psm1` (functions) + `LsiGitCheckout.ps1` (entry point)
+- Post-checkout scripts now execute via `pwsh` instead of `powershell.exe`
+- Replaced verbose null-check patterns with `??` null-coalescing operator
+
+### Added
+- `LsiGitCheckout.psm1` module file containing all function definitions
+- `LsiGitCheckout.psd1` module manifest
+- `Initialize-LsiGitCheckout` function for module state initialization
+- Automated unit tests using Pester 5.x (`tests/LsiGitCheckout.Unit.Tests.ps1`)
+- Automated integration tests for all 16 test configs (`tests/LsiGitCheckout.Integration.Tests.ps1`)
+
 ## [7.1.0] - 2025-09-02
 
 ### Added

CLAUDE.md

@@ -0,0 +1,87 @@
+# CLAUDE.md — LsiGitCheckout
+
+## Project Overview
+
+PowerShell-based dependency management tool that checks out multiple Git repositories to specified versions. Module architecture: `LsiGitCheckout.psm1` (functions) + `LsiGitCheckout.ps1` (entry point). Version 8.0.0, by LS Instruments AG.
+
+## Running the Tool
+
+```powershell
+.\LsiGitCheckout.ps1                                    # defaults to dependencies.json
+.\LsiGitCheckout.ps1 -InputFile "path/to/deps.json"     # custom config
+.\LsiGitCheckout.ps1 -DryRun                             # preview without executing
+.\LsiGitCheckout.ps1 -EnableDebug -EnableErrorContext     # full debug output
+```
+
+Key parameters: `-InputFile`, `-CredentialsFile`, `-DryRun`, `-EnableDebug`, `-DisableRecursion`, `-MaxDepth` (default 5), `-ApiCompatibility` (Strict|Permissive), `-DisablePostCheckoutScripts`, `-EnableErrorContext`
+
+## Testing
+
+### Automated Tests (Pester 5.x)
+
+```powershell
+# Install Pester if needed
+Install-Module Pester -Force -MinimumVersion 5.0
+
+# Unit tests — fast, no network required
+Invoke-Pester ./tests/LsiGitCheckout.Unit.Tests.ps1 -Output Detailed
+
+# Integration tests — requires network access to GitHub test repos
+Invoke-Pester ./tests/LsiGitCheckout.Integration.Tests.ps1 -Output Detailed
+```
+
+### Manual Testing
+
+Test configs in `tests/` can also be run manually:
+
+```powershell
+.\LsiGitCheckout.ps1 -InputFile tests/dependencies_semver.json -DryRun
+```
+
+There are 16 test JSON configs covering SemVer, Agnostic, API incompatibility, custom paths, post-checkout scripts, and recursive dependencies.
+
+## Architecture
+
+- **Module**: `LsiGitCheckout.psm1` — all function definitions (~35 functions)
+- **Entry point**: `LsiGitCheckout.ps1` — param block, module import, initialization, main execution
+- **Manifest**: `LsiGitCheckout.psd1` — module metadata, exported functions
+- **Two dependency resolution modes**: SemVer (recommended, automatic version resolution) and Agnostic (explicit tag-based)
+- **Configuration**: JSON files — `dependencies.json` for repos, `git_credentials.json` for SSH keys
+- **Recursive processing**: walks dependency trees with conflict detection, max depth configurable
+- **SSH**: PuTTY/Pageant integration for authentication (`.ppk` key format)
+- **Post-checkout scripts**: optional PowerShell scripts run after successful checkouts
+
+## Coding Conventions
+
+- **PowerShell 7.6 LTS** required (`#Requires -Version 7.6`)
+- **Function names**: PascalCase Verb-Noun (e.g., `Test-GitInstalled`, `Parse-VersionPattern`, `Get-SemVersionIntersection`)
+- **Documentation**: comment-based help blocks (`.SYNOPSIS`, `.DESCRIPTION`, `.PARAMETER`) on all functions
+- **Logging**: use `Write-Log` with levels: Info, Warning, Error, Debug, Verbose
+- **Error handling**: wrap operations in `Invoke-WithErrorContext -Context "description" -ScriptBlock { ... }`
+- **Module state**: `$script:` prefix for module-scoped variables (e.g., `$script:RepositoryDictionary`, `$script:DryRun`)
+- **Initialization**: call `Initialize-LsiGitCheckout` to set module state from entry point parameters
+- **CHANGELOG**: follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) format with SemVer versioning
+
+## Project Structure
+
+```
+LsiGitCheckout.ps1       # Entry point script (~230 lines)
+LsiGitCheckout.psm1      # Module with all functions (~2520 lines)
+LsiGitCheckout.psd1      # Module manifest
+CHANGELOG.md             # Version history
+README.md                # Comprehensive user documentation
+docs/
+  comparison_guide.md    # vs Google Repo Tool
+  migration_guide.md     # Migration strategies
+examples/                # 7 example dependency JSON configs
+tests/                   # 16 test JSON configs + Pester test files
+  LsiGitCheckout.Unit.Tests.ps1         # Unit tests (no network)
+  LsiGitCheckout.Integration.Tests.ps1  # Integration tests (needs network)
+```
+
+## Key Domain Concepts
+
+- **SemVer mode**: uses `"Dependency Resolution": "SemVer"` and `"Version": "x.y.z"` fields. Supports floating versions (`"2.1.*"`, `"2.*"`)
+- **Agnostic mode**: uses `"Tag"` and `"API Compatible Tags"` fields for explicit version control
+- **Repository Dictionary** (`$script:RepositoryDictionary`): central tracking structure for all repositories being processed across the dependency tree
+- **Immutable config**: once a repo's resolution mode is set, it cannot change during processing

LsiGitCheckout.code-workspace

@@ -0,0 +1,8 @@
+{
+	"folders": [
+		{
+			"path": "."
+		}
+	],
+	"settings": {}
+}