## Summary - generate the paas-charm V2 metadata contract on Ubuntu 26.04 for all six 12-factor extensions: `app`/`app-image`, `peers`/`peers`, and uv - generate one `app-secret-key` option of type `secret` for every V2 framework, removing the separate V2 `app-secret-key-id` option - validate canonical `paas-config.yaml` keys (`port`, `metrics-port`, and `metrics-path`) during extension expansion and pack - constrain all six V2 init templates to the published prerelease range `paas-charm>=2.0.dev0,<3` - restore Express to the init command overview and document V1/V2 selection, generated differences, config staging, and manual migration ## Compatibility V1 output is unchanged. Ubuntu 22.04/24.04 extensions still generate the `secret-storage` peer relation and their existing string/secret-ID option pairs. Ubuntu 26.04 remains experimental and still requires `CHARMCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=1`. The V2 dependency intentionally admits the currently published `2.0.dev0` prerelease and future compatible 2.x releases, while excluding incompatible stable 1.x and unreviewed future major versions. ## Validation - `uv run pytest -q tests/extensions/test_app.py -k '26_04_uses_v2_snippet or v1_secret_option_names_unchanged or test_apply_extensions_correct'` — 13 passed - `uv run pytest -q tests/integration/commands/test_init.py -k framework_profile_charm_user` — 6 passed - `uv run pytest -q tests/extensions tests/integration/commands/test_expand_extensions.py tests/integration/commands/test_extensions.py` — 84 passed - Ruff check and format check on all touched Python files — passed - `make setup-docs && make docs` — passed with zero Sphinx warnings - `make lint-docs` — passed, including spelling, terminology, Sphinx lint, and link checking - targeted Vale check for changed documentation — passed - pre-commit hooks — passed Please review the V2 contract alignment and migration guidance. This PR is intentionally left as a draft.