implement-plan

# Implement Plan Execute an implementation plan file. ## Task Tracking At the start, use `TaskCreate` to create a task for each step: 1. Resolve and read the plan file 2. Read context files 3. Run `/implement` skill 4. Update plan status ## Step 1: Resolve and Read the Plan File Determine which plan file to implement using these rules in order: 1. **Explicit path** — If an absolute or relative path was passed, use it 2. **Explicit slug** — If a slug was passed (e.g., `add-image-cache`), resolve to `.turbo/plans/<slug>.md` if that file exists; otherwise fall through to rule 5 before erroring 3. **Single file** — Glob `.turbo/plans/*.md`. If exactly one plan exists, use it 4. **Most recent** — If multiple plans exist, use the most recently modified 5. **Unexpanded shell** — If a slug or path was passed but resolved to no plan, derive `<slug>` from the basename (stripping `.md`) and check `.turbo/shells/<slug>.md`. If it exists, halt with: "`<slug>` is a shell that needs expansion first. Run `/pick-next-shell` to expand and implement it." 6. **Legacy fallback** — If `.turbo/plans/` does not exist but `.turbo/plan.md` exists, use it 7. **Nothing found** — If no plan matched any rule above, tell the user to run `/turboplan` (for a new task) or `/pick-next-shell` (for existing shells) and stop If multiple plans exist and the most-recent choice is non-obvious (e.g., several plans were modified within the same minute), use `AskUserQuestion` to let the user pick from the candi...