---
name: radin-plan
description: |
  Write a step-by-step implementation plan for one backlog entry, without
  touching code. Scope is one task (a title/keyword), not the whole backlog.
  Use for /radin-plan, "plan this backlog entry", "write a plan for X before
  we execute it". radin-execute delegates here for any entry too complex to
  implement directly.
---
# Plan a Backlog Entry

Turn one backlog entry into one or more implementation plans, without writing
any code. It runs inline in whichever context invokes it. A caller that cannot
reach the user says so in its prompt; the branches below marked
"non-interactive" are then the defaults, and anything only the user could
settle is reported and stops the run.

## Step 1: Resolve the task scope

```bash
RADIN_CLI backlog plan-target "<scope id/title/keyword>"
```

It prints `id`/`title`/`task_file`/`plan_file` lines, plus one
`plan<TAB><path>` line per plan the entry already has. Route on its exit code:

- **0**: resolved and unplanned. Use it.
- **1**: nothing matches. The task isn't in the backlog yet: classify it into
  `feat`/`fix`/`chore`/`refactor` (rubric in `skills/radin-record/SKILL.md`),
  create it without asking, then re-run `plan-target` on the printed id.

  ```bash
  RADIN_CLI backlog add <category> "<short title>" <<'EOF'
  <the task as the caller stated or clearly implied it, and why it matters
  if not already obvious>
  EOF
  ```

- **2**: several entries match; it prints them as `candidate` lines on stderr.
  Ask which one.
- **3**: already planned; the `plan` lines are the existing paths. Show them and
  ask whether to re-plan (overwrite) or stop. Stop unless confirmed.

Non-interactive, for all three: report what `plan-target` printed and stop. The
scope came from an existing entry, so no match means backlog drift — the run
adds no entry, picks no candidate among several, and overwrites no plan.

## Step 2: Judge whether the scope should split

Invoke `/ponytail:ponytail` and apply its ladder: does this entry need more than one
plan? Lean toward NOT splitting. Split only when the entry genuinely
bundles multiple unrelated, independently plannable changes.

Interactive: state your read (split or not, and why) and confirm it.
Non-interactive: take the default (no split) without asking.

- **Not splitting**: the sub-task list is the entry itself.
- **Splitting**: show the proposed sub-tasks (short titles, one-line
  description each, full coverage, no overlap) and confirm. Confirmed or
  edited: use that list. Rejected: fall back to the single-item list.

## Step 3: Write each plan

Step 1 printed `task_file` and `plan_file`; a task's file never moves, so
neither is re-resolved between sub-tasks. For each sub-task, in order:

1. Read the entry's file. A sub-task from a split has only its one-line
   Step 2 description as scope, so plan just that part.
2. Explore the repo to understand the current state of the codebase, if you
   haven't already: structure, affected files, patterns, constraints. Carry the
   project's own vocabulary into the plan — its glossary or domain-model doc
   where it has one — and respect any ADR covering the area you're touching.

   - Use `codebase-memory-mcp`'s MCP tools before Grep/Glob/Read:
     `get_architecture` for the shape of an unfamiliar area, `search_graph` to
     find the symbols in scope, `trace_path` for every caller and callee the
     plan will touch, `get_code_snippet` to read one function, `query_graph`
     (after `get_graph_schema`) for anything Cypher-shaped. Run
     `index_repository` first when `list_projects` doesn't list this repo — a graph hit is a pointer: read the file before you cite or edit it, and never conclude something is absent from an empty result.
   - Prefer `rtk`-wrapped commands when `command -v rtk` succeeds. Add
     `headroom loc` for the shape of a repo you have not seen before, when
     `command -v headroom` succeeds.
   - A plan hinging on third-party API or library behavior that local code
     cannot confirm goes to `/mattpocock-skills:research` against primary
     sources first. Non-interactive: that skill spawns its own agent whose
     result may not come back, so report the unconfirmed behavior and stop.
3. Sketch the seams at which the change will be tested. Prefer an existing seam
   to a new one, and use the highest seam available. If new seams are needed,
   propose them at the highest point you can. The fewer seams across the
   codebase, the better — the ideal number is one.

   Interactive: check with the user that these seams match their expectations,
   before anything is written.
   Non-interactive: record the seam you chose in the plan's `## Testing`
   section and write on.
4. Invoke `/ponytail:ponytail` and apply its ladder to produce the plan. When
   the plan has to place a new module boundary or reshape an interface, invoke
   `/mattpocock-skills:codebase-design` for that part instead of inventing
   your own vocabulary for it. Write it to the template below, section by
   section — the template is the output contract, and every plan radin writes
   has that shape.

   Non-interactive: synthesize the plan from the entry, the repo, and what this
   conversation already holds. A question none of those three answers is the
   report line that ends the run, not a decision to leave open in the plan.
5. Save the plan at the `plan_file` path Step 1 printed. For a sub-task from a
   split, re-run `plan-target "<id>" "<sub-slug>"` with the sub-task's short
   title in lowercase-hyphen form and use the `plan_file` it prints.
6. Insert the pointer via the CLI (appends `**Plan:** <path>` to the task's
   file, after any earlier `**Plan:**` lines):

   ```bash
   RADIN_CLI backlog add-plan "<id>" "<the plan_file path>"
   ```

7. Report: `✅ <id> planned. Plan: <path>. Review findings: <n or none>.` The
   count comes from Step 4, so write this line after that sub-task's review
   pass, not before it.

Planning and executing are separate tools, so this skill's whole output is the
plan file(s) it writes plus the one `**Plan:**` line the CLI appends to the
scoped task's file. Everything else in the tree stays exactly as you found it:
no source file edited, no build or test run, no commit, nothing else in the
scoped task's file, and no other task's file touched.

### The plan template

<plan-template>

```markdown
# Plan: <task title>

**Task:** `<task id>` — <the `task_file` path Step 1 printed>
**Reading this:** the entry holds the problem, the acceptance criteria and
every `**Decision:**` line; this plan holds the how and restates none of it.

## Outcome

<One or two lines: what is true of the codebase once this plan is implemented.>

## Decisions

<A LONG, numbered list: every choice the executor would otherwise have to make,
each one settled here. Each entry in the format:>

1. <The question> → <the settled answer>. Why: <one line>.

<Every claim about the current code carries its source inline — `path:line`, or
the read-only command that produced it.>

<This list is exhaustive: a decision the executor has to invent is a defect in
this plan, so keep going until nothing about the how is open.>

## Changes

<One entry per file to touch — the minimum set, no more:>

- `<path>` — <the concrete change, in prose: the symbols to touch and what
  becomes of each. No line numbers, and no pasted code.>

<Exception for code: a snippet that encodes a decision more precisely than
prose can — a schema, a type shape, a state machine, the exact string a test
asserts on. Inline it in the entry it belongs to, trimmed to the
decision-rich part.>

## Order

<The steps that must happen in a given order, numbered, each with the one line
saying why it gates the next — or "Any order." when nothing does.>

## Testing

**Seam:** <the seam from the Step 3 sketch, and why it's the highest available.>
**Prior art:** <an existing test in this repo whose shape the new test copies.>
**What to test:** <external behavior only — what a caller observes, never an
implementation detail.>

- [ ] <one line per check to run, as the command that runs it>

## Out of scope

<What a reader might expect here and this plan deliberately does not do, each
with where it does belong — or "Nothing — the entry's scope is covered in full
above.">
```

</plan-template>

## Step 4: Review each plan before handing it off

A plan is a proposal, so review it before `radin-execute` builds on it. For
each plan file just written:

1. Invoke `/thermo-nuclear` against the plan file's content (not the
   codebase): does the proposed approach itself carry a structural issue
   the rubric flags?
2. Invoke `/ponytail:ponytail-review` against the same file: speculative
   flexibility, reinvented stdlib, single-caller layers?
3. Fix each finding by editing the plan file in place. The fix belongs in
   the plan itself, and nothing goes to the backlog.

## Step 5: Report back

One line per plan, as Step 3's step 7 already printed it, then:

`Next: radin-execute (or a human) can implement from the plan(s) above.`