rpi-plan

Create an implementation plan through an interactive, gated flow. Consumes research.md from /rpi-research

RPI principle: Research documents what is. Plan decides what should change. Implement performs the change and verifies it.

Announce at start: "Starting /rpi-plan."

Core Principle: Gated, Not Single-Shot

Plans built in one shot tend to bake in assumptions. This skill enforces four explicit gates so you can correct course before the plan crystallizes:

1. Understanding gate — present what's understood; resolve open questions
2. Design option gate — present 2-4 options grounded in research; pick one
3. Phase outline gate — confirm phase boundaries before writing details
4. Draft review gate — iterate on the written plan until satisfied

Each gate uses AskUserQuestion.

Setup

1. Run "$SKILL_BASE_DIR/setup.sh" "<slug>" (extract <slug> from $ARGUMENTS). Parse stdout for REPO, TOPIC_SLUG, ARTIFACT_DIR. $SKILL_BASE_DIR is the "Base directory for this skill" path shown at the top of this prompt.
   • If exit 2, AskUserQuestion for slug.

Pre-flight Validation

• If <ARTIFACT_DIR>/plan.md exists, AskUserQuestion: Overwrite / New slug / Abort.
• Check <ARTIFACT_DIR>/research.md — if missing, Abort and tell the user to run /rpi-research first.
• Check <ARTIFACT_DIR>/research.md — note presence; it determines Step 1's branch below.

Process

Step 1: Load context

1. Read <ARTIFACT_DIR>/research.md fully.
2. Read every file referenced under ## Code References whose contents will materially shape the plan. Use the Read tool with no offset/limit on the most relevant 3-5 files; skim the rest.

Step 2: Gate 1 — Understanding

Present a focused summary:

Based on <research.md | inline research>, here's what I understand:

- <current implementation detail with file:line>
- <key pattern or constraint discovered>
- <potential complexity / edge case>

Open questions I couldn't resolve from the code:
- <question 1>
- <question 2>

Ask the user each open question (batch when ≤4 questions; otherwise prioritize the load-bearing ones). Only ask questions code can't answer — don't waste a gate on things you could verify with one more file read.

If the user corrects a stated understanding, verify the correction by reading the relevant code before accepting it. Do not just take dictation.

Step 3: Gate 2 — Design Option Pick

Surface 2-4 plausible approaches, each citing research findings as evidence. Skip this gate only if there's genuinely one obvious approach (and say so explicitly).

For each option:

**Option A: <name>**
- Approach: <one sentence>
- Evidence: <file:line refs from research showing why this fits>
- Tradeoffs: <pros / cons>

**Option B: <name>**
...

Use AskUserQuestion with the options as choices. Capture the user's pick + rationale in a buffer — it will land in the plan's header.

Step 4: Gate 3 — Phase Outline

Propose phase boundaries (1-line each). Each phase must be independently testable and produce a working unit.

Proposed phasing:

1. <Phase 1 name> — <what it produces; validation command>
2. <Phase 2 name> — <what it produces; validation command>
3. <Phase 3 name> — <what it produces; validation command>

Total: ~<N> tasks across <M> phases.

Use AskUserQuestion: Confirm phasing / Adjust phase boundaries / Adjust task granularity / Abort.

If the user requests adjustments, iterate until they confirm. Keep phase boundaries independently testable and adjust task granularity until the outline is clear enough to draft.

Step 5: Gate 4 — Draft and Review

Read ./plan-template.md, then write the plan to <ARTIFACT_DIR>/plan.md using that structure. Then announce:

Plan drafted at <path>.

Please review:
- Are tasks small enough for one fresh subagent to complete safely, with clear tests/validation?
- Are success criteria specific and runnable?
- Anything missing or out of scope to drop?

Iterate via Edit until the user signals satisfaction. No open questions in the final plan — if something is unresolved, return to Gate 2 or 3.

Plan Template (dw-05 format)

Read ./plan-template.md and use that exact structure for <ARTIFACT_DIR>/plan.md. The template includes required execution progress fields, task/phase format, and task granularity guidance.

Completion

1. Confirm artifact path, phase count, task count.
2. Instruct: "Plan ready at <ARTIFACT_DIR>/plan.md. Review once more, then run /rpi-implement <slug> to execute."

Red Flags

Stop and reconsider if:

• A gate gets skipped because "the user will catch it later" — gates exist because they're cheaper than fixing the plan after implementation starts.
• An option at Gate 2 has no evidence from research — that's a design hunch, not a grounded option. Either find the evidence or drop the option.
• The plan would contain placeholders or "TBD" — return to the appropriate gate; placeholders become bugs.
• The plan is becoming vague because the scope is large — tighten phase boundaries, task granularity, success criteria, and scope guards before drafting.

Notes on the four-gate flow

Gates aren't ceremony — each one prevents a specific failure mode:

Gate	Prevents
Understanding	Planning around a misread of current state
Design option	Locking in an approach the user wouldn't have picked
Phase outline	Phases that aren't independently testable or are wrongly ordered
Draft review	Tasks too vague for /rpi-implement to dispatch cleanly

If a gate feels redundant in a given session (e.g., the user gave the design decision upfront), state the assumption explicitly and ask once for confirmation rather than skipping silently.