plan-slice

Plan Slice

You restructure an existing feature plan into vertical slices — ordered increments where each slice delivers something that runs and can be verified end-to-end before moving to the next slice.

Announce at start: "I'm using the plan-slice skill. I'll restructure your plan into vertical slices with code skeletons."

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Step 1 — Select the Plan File

List available basic plan files (exclude -dev.md and -ticket.md files that are already outputs):

ls ~/.claude/plans/ 2>/dev/null | grep -v '\-dev\.md' | grep -v '\-ticket\.md' | sort -r

Use AskUserQuestion with a single question to let the user pick which plan to slice. Show the filenames as options (most recent first). Include a "Let me type the path manually" escape hatch.

After selection, read the plan file in full.

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Step 2 — Read Supporting Context

Extract the file paths listed under "Files to Create" and "Files to Modify" in the plan. Read those files from the codebase (if they exist) to understand:

• Naming conventions and code style
• Method signatures and patterns already in use
• DB schema conventions
• Test patterns

This context is essential for generating realistic code skeletons.

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Step 3 — Determine Slice Boundaries

Analyse the feature end-to-end and identify 3–6 vertical slice boundaries. Each slice must:

• Deliver a working, independently testable increment — not "all DB work" or "all API work"
• Touch all layers required for that increment (DB + service + API + UI as appropriate)
• Be named by what it delivers, not which layer it is

Good slice names: "Core data model", "Create flow end-to-end", "List view with filters" Bad slice names: "Database layer", "Backend", "Frontend"

Consider natural dependencies — a "List view" slice can't come before the "Core data model" slice. Order slices so each one builds on the last.

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Step 4 — Write the Sliced Plan

Filename: take the input filename, strip .md, append -dev.md. Example: 2026-05-22-user-notifications.md → 2026-05-22-user-notifications-dev.md

Check for collisions:

ls ~/.claude/plans/ 2>/dev/null | grep "<derived-slug>-dev" || echo "clear"

If collision, append -2, -3, etc. before .md.

Write ~/.claude/plans/<filename>-dev.md using this structure:

---
date: YYYY-MM-DD
project: <project name from original plan>
feature: <feature name from original plan>
type: vertical-slice-plan
---

# <Feature Name> — Developer Plan (Vertical Slices)

> Implement slices in order. Each slice should pass its own verification before moving to the next.

**Slices:** <N total> | **Estimated:** <X days>

---

## Slice 1: <Name — describes what is delivered>

**Delivers:** <One sentence: what a tester/developer can verify once this slice is complete>
**Layers:** <e.g. DB + Service, or API + UI + Tests>

- [ ] <Sub-task — be specific enough to execute without looking elsewhere>

  ```<lang>
  <Key method signature, SQL statement, or template snippet>
  <Show the critical logic structure — not boilerplate, just the decision points>

• <Test sub-task — what to write and what to verify>
• Verify:
• Commit: feat: <short description>

---

Slice 2:

Delivers: <...> Layers: <...>

• Verify: <...>
• Commit: feat: <...>

<Repeat for all slices. Aim for 3–6.>

---

Full Verification

<Copy the Verification section from the original plan — this is the end-to-end acceptance check once all slices are complete.>

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## After Writing

Tell the user:

> "✅ Developer plan saved to `~/.claude/plans/<filename>-dev.md`
>
> The original plan is unchanged at `~/.claude/plans/<original-filename>.md`.
> Run `/plan-ticket` if you also want a PM ticket for this feature."