`: - The first token is the path to a slice map under `.rpiv/artifacts/slices/`. - The remainder (`Slice N: <title>`) names the **single** slice to design. Parse `N` from `Slice (\d+)`. - `--upstream <path>` *(repeats, optional)* — a direct dependency's per-slice design doc, injected by the design fanout once that dependency completes. Read each one's `## Key Interfaces` (the decided contract this slice builds on) and `## Notes / Deferred` (to detect an undecided fork). Absent ⇒ this slice is a root (no upstream dependency). Design **only** that slice. Respect its `Out of scope` — anything there belongs to another slice's design. If the slices path is missing or `Slice N` can't be parsed, print an error and stop — it's a dispatch error. ## Metadata ```! node "${SKILL_DIR}/../_shared/now.mjs" echo node "${SKILL_DIR}/../_shared/git-context.mjs" ``` Copy values verbatim. `<iso>` is the first tab-separated field; `<slug>` is the second. ## Steps 1. **Read the slice map fully** and locate the `## Slice N:` section — its Scope, Draws on, Depends on, Out of scope. 2. **Read the slice's footing**: the `Draws on` references (research sections + the source `file:line`s it rests on). Read those files fully. This is **targeted** — read what the slice names, do **not** run discovery/analysis subagents. 3. **Read each `--upstream` dependency design** (if any were passed): from each, read its `## Key Interfaces` (the decided contract this slice depends on — build against it, do **not** redesign it) and its `## Notes / Deferred`. If a contract this slice **depends on** is still an undecided fork there (the dependency parked options rather than deciding), escalate — see Step 5. Read **only** the direct upstreams you were handed; do not chase their transitive dependencies (synthesize reconciles the rest). 4. **Design this slice** — decide its shape and record: - **Approach** — the architecture decision(s) for this slice and why. - **File map** — each file to add/change and what changes (`path — add|change — what`). - **Key interfaces** — the types/signatures/exports the slice introduces or touches. - **Integration points** — where this slice wires into existing code (and into sibling slices it depends on, by file/symbol — referencing the real shapes from the upstream `## Key Interfaces`). - **Success criteria** — concrete `- [ ]` checks that prove the slice works. 5. **Resolve ambiguity:** decide from the slice map, the upstream designs, research, and code wherever you can. Use `ask_user_question` (2–4 concrete options, one at a time) ONLY when you can't settle it from those inputs — either a genuine design fork within this slice, **or** a contract this slice depends on is still an undecided fork in an upstream's `## Notes / Deferred`. Do **not** ask the user to approve the finished design — the grade panel owns that. - `Header` is capped at ≤16 characters (`MAX_HEADER_LENGTH = 16` — longer values are rejected). 6. **Write the design doc** (below), `status: ready`. 7. **Print the path**, then a one-line summary: `Slice N design: <k> files, <m> success criteria`. ## Output document Path: `.rpiv/artifacts/designs/<slug>_slice-<N>_<topic>.md` (`<topic>` = kebab-case of the slice title). ```markdown --- date: <iso> author: <author> repository: <repo> branch: <branch> commit: <commit> topic: "<slice title>" source: <slices-path> slice_n: <N> slice_title: "<title>" depends_on: [<slice numbers this slice depends on>] status: ready tags: [design, slice] --- # Design — Slice <N>: <title> ## Approach <the architecture decision(s) for this slice, grounded in file:line> ## File Map - `path/to/file.ts` — add|change — <what and why> ## Key Interfaces <signatures / types / exports — code shape, not full implementation> ## Integration Points - `path:line` — <how this slice wires in; name sibling slices it couples to>  ## Success Criteria - [ ] <concrete, checkable> ## Notes / Deferred <assumptions made in lieu of a blocker question; anything pushed to another slice> ``` ## Hard rules - **One slice only.** Never design or touch work that the slice map assigns to a different slice. - **The path carries the slice.** The basename's `_slice-<N>_` segment is mandatory and must equal `slice_n` — the workflow resolves which slice a design belongs to from both, and a title that happens to look like an ID (`LV-2`, `DT-1`) never substitutes for it. - **Code shape, not implementation.** Interfaces, file map, decisions — `implement` writes the actual code later. - **No discovery/analysis subagents. No self-review.** Read the files the slice names; decide; write. Ask only to clear a genuine blocking fork. - **Build against decided upstream contracts.** When `--upstream` designs are provided, consume their `## Key Interfaces` as fixed — never redesign a dependency's contract. If a contract you depend on is undecided (parked in the upstream's `## Notes / Deferred`), escalate (Step 5), don't guess.

# Design Slice > Design ONE vertical slice from a slice map in isolation — its architecture decisions, file map, key interfaces, integration points, and success criteria — and write a per-slice design doc to .rpiv/artifacts/designs/. Single-pass, no research subagents, no self-review; asks the user only when a genuine design fork blocks the slice. Dispatched once per slice by a design fanout; the per-slice designs are later merged by synthesize. Use as a fanout unit, not standalone. - Skill: `juicesharp/design-slice` (Agent Skill) - Install (CLI): `npx skillmds@latest add juicesharp/design-slice` - Raw SKILL.md: https://api.skillmd.com/api/skills/juicesharp/design-slice/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Research & Search - Author: juicesharp (https://skillmd.com/u/juicesharp) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/juicesharp/design-slice --- # Design Slice You design **one** vertical slice from a slice map, in isolation, and write its design doc. One pass. You do **not** decompose (the slice is already cut), implement, or self-review — the workflow's grade panel judges your output. You **may** ask the user only when a genuine design fork blocks this slice. ## Input `$ARGUMENTS` — ` Slice N: `: - The first token is the path to a slice map under `.rpiv/artifacts/slices/`. - The remainder (`Slice N: <title>`) names the **single** slice to design. Parse `N` from `Slice (\d+)`. - `--upstream <path>` *(repeats, optional)* — a direct dependency's per-slice design doc, injected by the design fanout once that dependency completes. Read each one's `## Key Interfaces` (the decided contract this slice builds on) and `## Notes / Deferred` (to detect an undecided fork). Absent ⇒ this slice is a root (no upstream dependency). Design **only** that slice. Respect its `Out of scope` — anything there belongs to another slice's design. If the slices path is missing or `Slice N` can't be parsed, print an error and stop — it's a dispatch error. ## Metadata ```! node "${SKILL_DIR}/../_shared/now.mjs" echo node "${SKILL_DIR}/../_shared/git-context.mjs" ``` Copy values verbatim. `<iso>` is the first tab-separated field; `<slug>` is the second. ## Steps 1. **Read the slice map fully** and locate the `## Slice N:` section — its Scope, Draws on, Depends on, Out of scope. 2. **Read the slice's footing**: the `Draws on` references (research sections + the source `file:line`s it rests on). Read those files fully. This is **targeted** — read what the slice names, do **not** run discovery/analysis subagents. 3. **Read each `--upstream` dependency design** (if any were passed): from each, read its `## Key Interfaces` (the decided contract this slice depends on — build against it, do **not** redesign it) and its `## Notes / Deferred`. If a contract this slice **depends on** is still an undecided fork there (the dependency parked options rather than deciding), escalate — see Step 5. Read **only** the direct upstreams you were handed; do not chase their transitive dependencies (synthesize reconciles the rest). 4. **Design this slice** — decide its shape and record: - **Approach** — the architecture decision(s) for this slice and why. - **File map** — each file to add/change and what changes (`path — add|change — what`). - **Key interfaces** — the types/signatures/exports the slice introduces or touches. - **Integration points** — where this slice wires into existing code (and into sibling slices it depends on, by file/symbol — referencing the real shapes from the upstream `## Key Interfaces`). - **Success criteria** — concrete `- [ ]` checks that prove the slice works. 5. **Resolve ambiguity:** decide from the slice map, the upstream designs, research, and code wherever you can. Use `ask_user_question` (2–4 concrete options, one at a time) ONLY when you can't settle it from those inputs — either a genuine design fork within this slice, **or** a contract this slice depends on is still an undecided fork in an upstream's `## Notes / Deferred`. Do **not** ask the user to approve the finished design — the grade panel owns that. - `Header` is capped at ≤16 characters (`MAX_HEADER_LENGTH = 16` — longer values are rejected). 6. **Write the design doc** (below), `status: ready`. 7. **Print the path**, then a one-line summary: `Slice N design: <k> files, <m> success criteria`. ## Output document Path: `.rpiv/artifacts/designs/<slug>_slice-<N>_<topic>.md` (`<topic>` = kebab-case of the slice title). ```markdown --- date: <iso> author: <author> repository: <repo> branch: <branch> commit: <commit> topic: "<slice title>" source: <slices-path> slice_n: <N> slice_title: "<title>" depends_on: [<slice numbers this slice depends on>] status: ready tags: [design, slice] --- # Design — Slice <N>: <title> ## Approach <the architecture decision(s) for this slice, grounded in file:line> ## File Map - `path/to/file.ts` — add|change — <what and why> ## Key Interfaces <signatures / types / exports — code shape, not full implementation> ## Integration Points - `path:line` — <how this slice wires in; name sibling slices it couples to>  ## Success Criteria - [ ] <concrete, checkable> ## Notes / Deferred <assumptions made in lieu of a blocker question; anything pushed to another slice> ``` ## Hard rules - **One slice only.** Never design or touch work that the slice map assigns to a different slice. - **The path carries the slice.** The basename's `_slice-<N>_` segment is mandatory and must equal `slice_n` — the workflow resolves which slice a design belongs to from both, and a title that happens to look like an ID (`LV-2`, `DT-1`) never substitutes for it. - **Code shape, not implementation.** Interfaces, file map, decisions — `implement` writes the actual code later. - **No discovery/analysis subagents. No self-review.** Read the files the slice names; decide; write. Ask only to clear a genuine blocking fork. - **Build against decided upstream contracts.** When `--upstream` designs are provided, consume their `## Key Interfaces` as fixed — never redesign a dependency's contract. If a contract you depend on is undecided (parked in the upstream's `## Notes / Deferred`), escalate (Step 5), don't guess.