# Fable Scope Discipline

> Use when implementing any change in existing code — when tempted to clean up nearby code, add unrequested validation or options, fix something "arguably in scope", or when the diff is growing past what was asked.

- **Type:** Skill
- **Install:** `agentstack add skill-dizzymii-fable-skills-fable-scope-discipline`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [DizzyMii](https://agentstack.voostack.com/s/dizzymii)
- **Installs:** 0
- **Category:** [AI & ML](https://agentstack.voostack.com/c/ai-and-ml)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [DizzyMii](https://github.com/DizzyMii)
- **Source:** https://github.com/DizzyMii/fable-skills/tree/main/skills/fable-scope-discipline
- **Website:** https://github.com/DizzyMii/fable-skills

## Install

```sh
agentstack add skill-dizzymii-fable-skills-fable-scope-discipline
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Scope Discipline

## Overview

Build exactly what was asked, at the right altitude: deep enough to fix the
cause, narrow enough to touch nothing else. Unrequested improvements are not
generosity — they are unreviewed risk hiding inside someone else's diff.

## Rules

1. **Implement what was asked.** Nothing speculative, nothing "while I'm
   here."
2. **Adjacency is not scope.** "Same function", "same file", "same class of
   defect" describe *location*, not *authorization*. The user's words define
   the task; nearness defines nothing.
3. **The argument test.** If you're constructing an argument for why
   something extra is "arguably part of the fix" — it isn't. Real scope
   never needs the argument. Put the argument in your report and let the
   user decide.
4. **The open-question test.** If the extra fix has an unresolved design
   choice (raise or clamp? rename to what?), that proves it's its own task.
   You can't settle a contract question inside someone else's bugfix.
5. **Right altitude.** Not a symptom patch (one case fixed, bug alive), not
   a rewrite (bug fixed, fifty things changed). Root cause, within scope.
6. **No drive-bys.** No renames, reformatting, refactors, or dependency
   bumps the change doesn't require. Diff noise buries the change.
7. **Touch budget.** Diff much larger than the ask implies → stop and
   re-check your altitude.
8. **Look before you delete or overwrite.** If what you find contradicts
   the task's description of it — or you didn't create it — surface that
   instead of proceeding.
9. **Discoveries go in the report.** Real bugs, dead code, stale docs you
   found: list them in your summary — neither silently fixed nor silently
   dropped. "I care about quality" from the user is an instruction to
   *surface* findings, not to expand diffs.

## Rationalizations (verbatim from baseline failure)

| Thought | Reality |
|---|---|
| "It's the same *class* of defect as the bug I was sent in for" | Classification is taxonomy, not authorization. The user named one defect. |
| "It lives in the same function's contract" | Location again. Contracts change by decision, not by proximity to your cursor. |
| "Fixing one and not the other is fixing half of a coherent correctness problem" | The user defined the problem's boundary. "Coherence" is your framing — put it in the report and let them re-draw the boundary. |
| "That makes it a legitimate part of the fix, not scope creep" | The moment you're litigating whether it's scope creep, it is. Done-with-the-argument ≠ authorized. |
| "Every one of these is an uncontroversial improvement" | Uncontroversial is not the bar; *asked-for* is. Improvements travel in their own reviewable diff. |
| "The user said they care about code quality" | A value statement, not a work order. Quality includes atomic, revertible, reviewable diffs. |

Provenance: rows 1–4 are verbatim Opus 4.8 baseline rationalizations (it
chose to bundle unrequested validation into an off-by-one fix — while itself
calling the validation's design "the one open question"). fable-skills test
logs, 2026-06-10.

## Red Flags — stop and shrink the diff

- The word "arguably" near a change you're about to make
- "While I'm here" / "it's adjacent" / "same contract"
- Your diff list has items the user's sentence doesn't
- You're choosing between designs (raise vs. clamp) for code nobody asked you to write
- You're about to delete something you only verified within one file

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [DizzyMii](https://github.com/DizzyMii)
- **Source:** [DizzyMii/fable-skills](https://github.com/DizzyMii/fable-skills)
- **License:** MIT
- **Homepage:** https://github.com/DizzyMii/fable-skills

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-dizzymii-fable-skills-fable-scope-discipline
- Seller: https://agentstack.voostack.com/s/dizzymii
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.