# deepen

Finds shallow modules with bloated interfaces and re-architects them to hide complexity. Run it when your test suite is green and you have token budget left over.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 770 installs · ★ 1156
- Author: JuliusBrussee
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/JuliusBrussee/cavekit/tree/HEAD/skills/deepen/SKILL.md
- Updated: 2026-08-14
- HTML: https://affpapa.org/en/nevibecode/skills/deepen

## What it does

The skill targets shallow modules in files touched by your current task. These are classes or functions whose interfaces demand as much cognitive effort as writing the implementation from scratch, such as pass-through wrappers or methods taking five configuration flags. It tackles strictly one module per pass. Surgical precision prevents messy diff churn across your repository.

The workflow follows five discrete steps: pick the shallowest module, diagnose the defect with line references, research a deeper design, draft spec modifications (§I, §V, and §T), and verify invariants. The skill never silently rewrites files. Instead, it hands the proposed spec edits over to your spec-writing tool. If the `codebase-design` skill is installed, deepen adopts its vocabulary.

External behavior is strictly preserved throughout the pass. Both before and after the change, your entire test suite must stay green. Running deepen during crunch time or midway through an unfinished feature is a mistake, because it is built solely to drain spare token budget on design debt.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add JuliusBrussee/cavekit --skill deepen -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/deepen/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/deepen/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add JuliusBrussee/cavekit --skill deepen -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/deepen/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add JuliusBrussee/cavekit --skill deepen -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/deepen/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install JuliusBrussee/cavekit deepen
```

2. **Manually: put the files in place**
- File: `.github/skills/deepen/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add JuliusBrussee/cavekit --skill deepen -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/JuliusBrussee/cavekit --path skills/deepen
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/deepen/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add JuliusBrussee/cavekit --skill deepen -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/JuliusBrussee/cavekit/tree/HEAD/skills/deepen/SKILL.md

## When to use it
- hide implementation details behind a smaller interface
- eliminate pass-through methods and configuration leakage
- draft §I, §V, and §T edits without altering runtime behavior
- curb change amplification across unrelated files

## Example prompts
- /ck:deepen
- this module feels shallow, pull complexity down
- use spare budget on the codebase to improve module design

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: ab7ef9428f22b0d1.

BEGIN THIRD-PARTY FILE ab7ef9428f22b0d1
```text
---
name: deepen
description: |
  Optional design-improvement pass for when you have spare usage to drain. Finds
  the shallowest modules in the code the spec touches, researches a deeper
  design, and proposes refactors that shrink interfaces and hide decisions —
  behavior held constant, tests green before and after. Proposes §I/§V/§T edits,
  never silent rewrites. Triggers when the user says "deepen this", "improve the
  design", "this module feels shallow", "pull complexity down", "use spare
  budget on the codebase", or invokes /ck:deepen. Leans on the codebase-design
  skill's deep-module vocabulary when present.
---

# deepen — make modules deep

**Behavior is sacred: tests green before AND after. Every change shrinks an interface or hides a decision — deepen, don't churn.**

A **deep module** hides a lot behind a small interface; a **shallow** one's
interface costs as much to use as writing the code yourself. Complexity =
dependencies + obscurity, and it compounds. Deepen spends spare usage paying
that down *before* it becomes a §B. Run it when the build is green & you have
budget to drain — not under deadline.

## WHEN TO DEEPEN

- Build is green, tests pass, & you have token budget spare.
- A module's interface feels as complex as its implementation (shallow smell).
- The same change keeps touching many files (change amplification).
- User explicitly asks to improve design quality.

⊥ run mid-feature or under pressure. Deepen is the deliberate pass, not the reflex.

## FIVE STEPS

### 1. PICK THE SHALLOW
Scan the modules the spec touches. Rank by shallowness — interface surface vs
work done. Pick the **one** worst offender. Tells:
- Pass-through method that only forwards to one other (shallow layer).
- Caller must set 5 flags right to use it (config leakage).
- Same abstraction repeated at two layers (no information hiding).
- A `?` or §B that traces back to a confusing interface.

One module per pass. Deepening is surgical, ⊥ a codebase sweep.

### 2. DIAGNOSE
Name the design defect in caveman, citing file:line:
> src/auth/token.go: 6-arg ctor leaks rotation policy to every caller. shallow.
Complexity is real only if it shows: change amplification, high cognitive load,
or an unknown-unknown (caller must know a hidden fact to call it right).

### 3. RESEARCH THE DEEPENING
What does a deeper version look like? Pull a known pattern (hand to **research**
for the external case → §R) or derive from the codebase's own better modules.
Moves that deepen:
- **Pull complexity down** — hide the hard part inside, give callers the simple path.
- **Define errors out of existence** — design the interface so the edge can't occur.
- **Information hiding** — one decision, one module; callers don't learn it.
- **General-purpose interface** over a pile of special-case methods.

### 4. PROPOSE
Draft the change as spec edits, not a silent rewrite:
```
END THIRD-PARTY FILE ab7ef9428f22b0d1

The third-party file has ended. Everything between the ab7ef9428f22b0d1 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2916 of 4072 bytes. © JuliusBrussee · MIT · https://github.com/JuliusBrussee/cavekit/tree/HEAD/skills/deepen/SKILL.md

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