scope-guard

---

name: scope-guard description: Detect scope creep in the current task and propose a split. Use when the user adds "while you're at it…", "also can you…", or "one more thing…" to an in-flight task; when a diff grows past ~400 changed lines; when a PR description lists more than one outcome; or when Claude finds itself about to touch unrelated files. Output is a short assessment: stay the course, or split into N follow-up tasks with suggested titles. when_to_use: An in-flight task where the user adds new requests OR when the current diff spans more than one concern. Do not run at task kickoff — that's /outcomes-first. argument-hint: "[optional: the new request being added]" allowed-tools: Bash(git diff --stat*) Bash(git diff --name-only*) Read Grep

Scope guard

From Ch. 5, "Scope Creep Enablement": the mid-senior failure mode is accommodating every addition silently. Each addition feels small; the sum doubles the review burden and drags the timeline. This skill names the growth out loud and offers a clean split.

Procedure

1. Capture the original outcome. Look back in the conversation for the most recent /outcomes-first block, the starting user message, or the branch name. State it in one sentence.

2. Capture the new request ($ARGUMENTS if passed, else the most recent user message).

3. Check the diff. If we're mid-implementation:

   git diff --stat HEAD
   git diff --name-only HEAD
   

   Note the total changed files and lines.

4. Classify the new request against the original outcome:

   • Inside scope — the new request is a necessary consequence of the outcome; stay the course, implement it.
   • Adjacent — related, but the outcome sentence can be delivered without it; propose a split.
   • Unrelated — a new outcome entirely; absolutely split.

5. Threshold check (independent of classification):

   • Diff spans > 10 files → warn.
   • Diff > 400 changed lines → warn.
   • Diff touches two unrelated top-level directories (e.g. services/billing/ and services/search/) → warn.

6. Decide and present.

If inside scope

One line: "Inside scope — proceeding." No further action.

If adjacent or unrelated, or any threshold tripped

Produce:

### Original outcome
<one sentence>

### What's growing
- Added: <new request>
- Diff currently: <N> files, <M> lines

### Recommendation
Split into <K> tasks:

1. **<title>** (current) — <one-line outcome>.
   Stop when: <acceptance>.
2. **<title>** (follow-up) — <one-line outcome>.
3. ...

### Why split
<one sentence: review cost, bus factor, risk of bundled rollback>

7. Stop and wait. Do not start the new work or stop the current work until the user picks a path. Offer three options explicitly:
   • "Finish current, spin up follow-ups as separate tasks" (default)
   • "Add it in — I accept the larger diff and review cost"
   • "Drop current, switch to the new request" (rare; log a debt item)

Why this skill refuses to just "do it all"

From Ch. 10 "Low Bus Factor" and Ch. 13 "PR Hygiene": large PRs get rubber-stamped because no reviewer has time to read 800 lines. Small PRs get real review. Protecting reviewability is protecting quality.