feature-new

# /feature-new -- scaffold a feature narrative Creates a feature document in an existing layer. The document follows the ULTRAPACK-style narrative template (Design / Plan / Verify / Conclusion) extended with explicit cross-references to layer invariants and global principles. ## When to use - Beginning design work on a new feature, **before** writing code - Migrating an in-flight feature from "scattered context" into the formal narrative - Creating a feature placeholder when planning future work that another session will pick up ## When NOT to use - One-line bug fixes that do not need a design phase (just commit) - Documentation-only changes (those go in handoffs or PR descriptions) - Refactors with no behavioral change (commit message is sufficient) ## Arguments ``` /feature-new <layer> <slug> [--title "..."] [--branch <name>] [--id F-NNN] ``` - `<layer>` -- existing layer name. Must be a directory under `docs/layers/`. If missing, suggest `/layer-new <layer>` first. - `<slug>` -- kebab-case feature identifier without the `F-NNN-` prefix. Examples: `api-key-rotation`, `audit-log`, `dual-encryption`. - `--title` -- human-readable feature title. If omitted, derive from slug by title-casing. - `--branch` -- git branch name. If omitted, default to `feature/<slug>`. - `--id` -- override the auto-allocated F-NNN. Use only when migrating a pre-existing feature with a known ID. Refuse if the ID already exists in this layer. ## Direction (what to do, in o...