carve

name	carve
description	Turn a PRD into a multi-phase implementation plan using tracer-bullet vertical slices, saved as a local Markdown file in ./plans/. Use when user wants to break down a PRD, create an implementation plan, plan phases from a PRD, or mentions "tracer bullets".

Carve — PRD to Plan

Break a PRD into a phased implementation plan using vertical slices (tracer bullets). Output is a Markdown file in ./plans/.

CLI tools — special case. If the PRD describes a command-line tool, suggest running /agent-cli in design mode before slicing. Locking flags, output formats, and error model up front prevents rework once vertical slices start landing.

Process

1. Confirm the PRD is in context

The PRD should already be in the conversation. If it isn't, ask the user to paste it or point you to the file.

2. Identify durable architectural decisions

Reasoning approach: Mentally trace 2-3 likely implementation paths through the PRD end-to-end. A "durable" decision is one all paths share. Reason through alternatives before listing — surface hidden assumptions, then prune. Recommended for this step: opus-4.7 with extended thinking (high effort).

Before slicing, identify high-level decisions that are unlikely to change throughout implementation:

• System architecture style
• Data model shape and key entities
• Authentication / authorization approach
• Third-party service boundaries
• Key constraints (compliance, performance, budget)

These go in the plan header so every phase can reference them.

3. Draft vertical slices

Reasoning approach: Hold the full PRD in mind while slicing. Each slice must cut through ALL integration layers — verify mentally before writing. Avoid horizontal-by-default thinking; if a phase only touches one layer, it's the wrong shape.

Break the PRD into tracer bullet phases. Each phase is a thin vertical slice that cuts through ALL integration layers end-to-end, NOT a horizontal slice of one layer.

Follow the rules in vertical-slice-rules.md.

Push back on slice creep. Every slice must trace to an explicit user story in the PRD. If a draft slice includes functionality not in the PRD ("while we're in there, let's also add X"), cut X — propose it as a follow-up phase or send it back to /blueprint. Phases that drift past the PRD turn /tdd into an open-ended design exercise.

Acceptance criteria must be verifiable. For each phase, every AC must be one of:

• (a) automated test — a test exists or can be written that asserts the behavior,
• (b) observable artifact — a row in a table, a file on disk, a log line, a metric, or
• (c) runnable command — make X, curl Y, psql -c "…" that returns a known result.

"It works" or "feature complete" do not qualify. If an AC can't be reduced to one of these three, sharpen it before the phase ships to /dispatch or /tdd.

4. Quiz the user

Present the proposed breakdown as a numbered list. For each phase show:

• Title: short descriptive name
• User stories covered: which user stories from the PRD this addresses

Ask the user:

• Does the granularity feel right? (too coarse / too fine)
• Should any phases be merged or split further?

Iterate until the user approves the breakdown.

5. Write the plan file

Create ./plans/ if it doesn't exist. Write the plan as a Markdown file named after the feature (e.g. ./plans/user-onboarding.md). Use the template in plan-template.md.