* Introduce a virgin Arch-based Nix flake E2E workflow that validates pkgmgr’s full flake installation path using shared caches for faster and reproducible CI runs.
* Introduced a unified **layer-based installer pipeline** with clear precedence (OS-packages, Nix, Python, Makefile).
* Reworked installer structure and improved Python/Nix/Makefile installers, including isolated Python venvs and refined flake-output handling.
* Fully rewrote **command resolution** with stronger typing, safer fallbacks, and explicit support for `command: null` to mark library-only repositories.
* Added extensive **unit and integration tests** for installer capability ordering, command resolution, and Nix/Python installer behavior.
* Expanded documentation with capability hierarchy diagrams and scenario matrices.
* Removed deprecated repository entries and obsolete configuration files.
- Fixed a crash in `pkgmgr code` caused by missing `directory` metadata by introducing `_resolve_repository_path()` with proper fallbacks to `repositories_base_dir` / `repositories_dir`.
- Updated `explore`, `terminal` and `code` tool commands to use the new resolver.
- Improved VS Code workspace generation and path handling.
* Fix floating 'latest' tag logic: dereference annotated target (vX.Y.Z^{}), add tag message to avoid Git errors, ensure best-effort update without blocking releases, and update unit tests (see ChatGPT conversation: https://chatgpt.com/share/69383024-efa4-800f-a875-129b81fa40ff).
* Add Git helpers for branch sync and floating 'latest' tag in the release workflow, ensure main/master are updated from origin before tagging, and extend unit/e2e tests including 'pkgmgr release --help' coverage (see ChatGPT conversation: https://chatgpt.com/share/69383024-efa4-800f-a875-129b81fa40ff)
* Expose DISTROS and BASE_IMAGE_* variables as exported Makefile environment variables so all build and test commands can consume them dynamically. By exporting these values, every Make target (e.g., build, build-no-cache, build-missing, test-container, test-unit, test-e2e) and every delegated script in scripts/build/ and scripts/test/ now receives a consistent view of the supported distributions and their base container images. This change removes duplicated definitions across scripts, ensures reproducible builds, and allows build tooling to react automatically when new distros or base images are added to the Makefile.
* Refine pkgmgr release CLI close wiring and integration tests for --close flag (ChatGPT: https://chatgpt.com/share/69376b4e-8440-800f-9d06-535ec1d7a40e)
* Add pkgmgr branch close subcommand, extend CLI parser wiring, and add unit tests for branch handling and version version-selection logic (see ChatGPT conversation: https://chatgpt.com/share/693762a3-9ea8-800f-a640-bc78170953d1)
* Add branch closing helper and --close flag to release command, including CLI wiring and tests (see https://chatgpt.com/share/69374aec-74ec-800f-bde3-5d91dfdb9b91)
* Add preview-first release workflow and extended packaging support (see ChatGPT conversation: https://chatgpt.com/share/693722b4-af9c-800f-bccc-8a4036e99630)
* Implement unified release helper with preview mode, multi-packaging version bumps, and new integration/unit tests (see ChatGPT conversation 2025-12-08: https://chatgpt.com/share/693722b4-af9c-800f-bccc-8a4036e99630)