Spec #2405 - Manifests without installer info

[Trenly]

📖 Description

This PR introduces the specification for the NoInstaller installer type (Issue #2405), enabling WinGet to recognize and manage packages that have no downloadable installer. The specification covers the complete design for:

• Installer Type Support — New NoInstaller enum value in InstallerTypeEnum
• Manifest Schema — New InstallerAvailabilityMessage field (manifest v1.30.0) with field constraints
• CLI Behavior — Install, upgrade, show, search, and uninstall command handling
• ARP Correlation — Using ProductCode and AppsAndFeaturesEntries for managing pre-installed software
• Use Cases — System components, pre-installed software, out-of-band distributions, version tombstones
• Validation — Validation-NoExecutables waiver requirement for community repository
• Architecture & Locale Scenarios — Mixed installability and availability across architectures and locales
• Future Enhancements — Issue Support for filtering packages on installer method #823 installer filtering with default exclusion of NoInstaller packages

The specification addresses all design feedback from PR #6157 and provides a comprehensive reference for implementation across winget-cli, winget-create, winget-cli-restsource, and winget-pkgs.

🔗 References

• Manifests without installer info #2405 — Manifests without installer info
• Add support for Manifests with No Installers #6157 — Add support for Manifests with No Installers (implementation PR)
• Package Tombstones #1900 — Version tombstones
• Support for filtering packages on installer method #823 — Filtering on installer method / installer type

🔍 Validation

No validation needed — This is a specification document that describes design intent and expected behavior. No code changes, manifests, or executable artifacts are included.

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Updated Release Notes (if applicable)
• Updated documentation (if applicable) — Specification document added
• Updated Copilot instructions (if build, architecture, or conventions changed)

📋 Issue Type

• Bug fix
• Feature
• Task — Specification documentation