Description

Added full support for an optional collection-level maturity field in collection manifests, enabling release channel gating, validation enforcement, and user-facing experimental notices in generated READMEs. Deprecated collections are now skipped during plugin generation, and experimental collections display a warning banner in both CLI plugin and VS Code extension READMEs.

• feat(schemas): Added optional maturity property (enum: stable, preview, experimental, deprecated) to root level in collection-manifest.schema.json, fixing the existing additionalProperties: false violation where experimental.collection.yml already used the field.
• feat(validation): Added collection-level maturity validation to Invoke-CollectionValidation in Validate-Collections.ps1 — rejects invalid values and allows omitted (defaults to stable).
• feat(plugins): Updated New-PluginReadmeContent and Write-PluginDirectory in PluginHelpers.psm1 to accept and forward collection maturity, injecting an experimental notice when maturity is experimental.
• feat(plugins): Updated Invoke-PluginGeneration in Generate-Plugins.ps1 to skip deprecated collections and pass maturity through to Write-PluginDirectory.
• feat(extension): Added {{MATURITY_NOTICE}} token to extension/templates/README.template.md and updated New-CollectionReadme in Prepare-Extension.ps1 to resolve the token with an experimental notice for experimental collections.
• feat(collections): Added maturity: experimental to github.collection.yml (all items already marked experimental) and design-thinking.collection.yml.
• refactor(scripts): Extracted main execution block in Generate-Plugins.ps1 into a testable Start-PluginGeneration function.
• test(scripts): Added 15+ Pester tests covering collection-level maturity validation (valid/invalid/omitted values), experimental notice in plugin and extension READMEs, deprecated collection skip, Start-PluginGeneration entry point, artifact frontmatter parsing, and DryRun mode paths.
• chore(collections): remove experimental maturity tags from GitHub backlog items and collection, and add experimental to all Design thinking collection and artifacts

Related Issue(s)

Closes #696

Type of Change

Select all that apply:

Code & Documentation:

• Bug fix (non-breaking change fixing an issue)
• New feature (non-breaking change adding functionality)
• Breaking change (fix or feature causing existing functionality to change)
• Documentation update

Infrastructure & Configuration:

• GitHub Actions workflow
• Linting configuration (markdown, PowerShell, etc.)
• Security configuration
• DevContainer configuration
• Dependency update

AI Artifacts:

• Reviewed contribution with prompt-builder agent and addressed all feedback
• Copilot instructions (.github/instructions/*.instructions.md)
• Copilot prompt (.github/prompts/*.prompt.md)
• Copilot agent (.github/agents/*.agent.md)
• Copilot skill (.github/skills/*/SKILL.md)

Other:

• Script/automation (.ps1, .sh, .py)
• Other (please describe):

Sample Prompts (for AI Artifact Contributions)

N/A — No AI artifacts were added or modified in this PR.

Testing

• Added Pester tests for all new code paths across four test files:
  • Validate-Collections.Tests.ps1 — collection-level maturity validation for all enum values, invalid values, omitted field, plus error-path coverage for missing fields, duplicate IDs, path mismatches, and maturity conflicts.
  • PluginHelpers.Tests.ps1 — experimental notice rendering (experimental, stable, omitted, null maturity), artifact frontmatter YAML parse failure, Write-PluginDirectory DryRun mode with agents, skills, missing sources, and missing shared directories.
  • Generate-Plugins.Tests.ps1 — deprecated collection skipped, experimental collection generated on PreRelease channel, plus Start-PluginGeneration function tests for success, failure, missing module, and default refresh logic.
  • Prepare-Extension.Tests.ps1 — maturity notice included for experimental collection, absent for stable and omitted maturity.
• Ran npm run plugin:generate to verify generated plugin READMEs contain the experimental notice for experimental collections.

Checklist

Required Checks

• Documentation is updated (if applicable)
• Files follow existing naming conventions
• Changes are backwards compatible (if applicable)
• Tests added for new functionality (if applicable)

AI Artifact Contributions

N/A — No AI artifacts were contributed.

Required Automated Checks

The following validation commands must pass before merging:

• Markdown linting: npm run lint:md
• Spell checking: npm run spell-check
• Frontmatter validation: npm run lint:frontmatter
• Skill structure validation: npm run validate:skills
• Link validation: npm run lint:md-links
• PowerShell analysis: npm run lint:ps

Security Considerations

• This PR does not contain any sensitive or NDA information
• Any new dependencies have been reviewed for security issues
• Security-related scripts follow the principle of least privilege

Additional Notes

• The hve-core-all.collection.yml diff shows only a cosmetic reorder of the display.featured and display.ordering fields — no functional change.
• Documentation in extension/PACKAGING.md, docs/architecture/ai-artifacts.md, and docs/contributing/ai-artifacts-common.md already covers the collection-level maturity field comprehensively; no additional doc updates were needed.
• The Start-PluginGeneration refactor replaces exit calls with return values, making the main execution block testable without process termination side effects.

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