anti-entropy-governance — Claude Code skill: how to install

---
name: anti-entropy-governance
description: "Use when touching retiring old logic, collapsing duplicate owners, removing fallbacks, or schema/persistence/source-of-truth boundaries; identify opportunities automatically; destructive execution requires explicit confirmation."
---

# Anti-Entropy

## Overview

Use this skill when the task is not merely "change code" but "remove old paths
safely without growing entropy".

This skill chooses between:

- `delete-first` for internal code retirement
- `compat-exception` for proven external dependency boundaries
- `confirmation-first` for irreversible state or an external contract whose
  distributed consumers cannot be observed

It does not replace `brainstorming`, `writing-plans`,
`systematic-debugging`, or `verification-before-completion`. It is a narrow
governance owner for retirement, fallback collapse, duplicate-owner cleanup,
and deletion safety.

## When to Use

Use when any of these are true:

- old logic, duplicate owners, or stale fallbacks should be retired
- a candidate fix is "delete old path" vs "add another fallback"
- internal keyword / phrase / trigger logic is being replaced by structured logic
- a new canonical owner exists and the old owner may still carry real behavior
- a cleanup, migration, or deprecation task touches schema, persistence,
  source-of-truth, or external compatibility boundaries
- the task risks confusing code retirement with live data deletion

Do not use for:

- pure additive feature work with no retirement decision
- tiny wording edits
- simple status or read-only Q&A
- normal bug fixes that do not involve owner collapse, fallback cleanup, or
  deletion choice

## Auto-Compose Boundary

This skill should be composed by other owners. It should not become a new
global hot-path entry.

Prefer composition from:

- `brainstorming` for approach selection involving retirement or persistence risk
- `writing-plans` for plans that delete old paths or touch schema / migration /
  persistence
- `systematic-debugging` when the tempting fix is fallback growth or
  delete-vs-retain
- `verification-before-completion` for cleanup / retirement / compatibility /
  migration closeout

Load automatically when the task touches owner collapse, fallback removal, or schema/persistence/source-of-truth boundaries. Automatic loading identifies and advises only; destructive execution still requires explicit scoped user confirmation.

## Core Principle

Default to reducing internal entropy, not preserving internal history.

Retirement is responsibility-scoped before it is carrier-scoped. Name the
obsolete or duplicated authority first. If the same carrier has a separately
evidenced legitimate role, remove the invalid responsibility and keep only
that role-scoped capability; this is not a compatibility exception. Apply
`delete-first` to the carrier once no legitimate responsibility remains.
Unknown consumers alone still do not justify retaining an internal carrier.

Use this rule:

- internal code retirement -> `delete-first`
- external compatibility boundary -> `compat-exception` with active dependency
  evidence; `confirmation-first` when distribution is proven but consumers
  cannot be observed
- persistent-state or irreversible source-of-truth object ->
  `confirmation-first`

Unknown alone neither proves an external dependency nor blocks internal
`delete-first`. Once distribution is proven, unobservable consumers also do not
prove deletion safe: inspect read-only. Before editing, require user-authored,
scoped authorization that explicitly accepts the concrete external risk.
An informed instruction may already supply it; otherwise disclose the risk
and request scoped confirmation.

Mentioning, loading, or discussing destructive-action rules never authorizes
destructive execution. Without explicit scoped user confirmation:

- no irreversible deletion is executed
- no destructive tool call is made
- no runnable destructive command is emitted as the next action
- no broad assent is reinterpreted as deletion approval

## Deletion Classes

Classify the deletion target first:

- `code-retirement`
  - source code
  - internal triggers
  - duplicate owners
  - stale fallback branches
  - compat-only carriers
  - dead tests/config tied to removed internal behavior

- `contract-carrying code`
  - schema definition files
  - migration files
  - public API contract code
  - host install/discovery code
  - persistence read/write logic

- `live-state mutation surface`
  - code or commands that would mutate live databases, object stores, queues,
    or other persistent state

- `derived-state`
  - rebuildable caches
  - generated indexes
  - temporary exports
  - recomputable artifacts

- `persistent-state`
  - live database tables / columns / rows
  - source-of-truth object storage files
  - user records
  - permission / identity / membership records
  - audit / billing / irreversible business records
  - non-rebuildable queue or event contents

## Default Path By Class

- `code-retirement` -> `delete-first`
- `contract-carrying code` -> classify by the Core Principle; internal-only
  retirement uses `delete-first` with high-risk verification
- `live-state mutation surface` -> inspect and classify; destructive execution
  still requires confirmation when it reaches persistent-state
- `derived-state` -> verify rebuildability first, then decide
- `persistent-state` -> `confirmation-first`

## Hard Stops

If the target is `persistent-state` or another irreversible source-of-truth
object:

- do not execute deletion automatically
- do not emit a runnable destructive command as the next action
- do not call a destructive tool
- do not interpret generic agreement as confirmation
- ask for explicit scoped user confirmation
- request backup / rollback / migration note when relevant

Examples that require confirmation:

- `DROP TABLE`
- `DROP COLUMN`
- `TRUNCATE`
- bulk delete of real business data
- deleting source-of-truth uploaded files
- deleting permission, identity, audit, billing, or membership records
- purging non-rebuildable queues or event streams

## Data Destruction Guard

When `confirmation-first` protects persistent-state or an irreversible
source-of-truth object, stop normal retirement flow and emit:

```text
Data Destruction Guard:
- Target Class:
- Exact Target(s):
- Environment:
- Why Irreversible:
- Backup / Rollback Note:
- Allowed Read-Only Next Steps:
- Blocked Destructive Steps:
- Confirmation Required: yes
- Status: awaiting scoped confirmation
```

Only explicit scoped confirmation can continue. Broad assent such as "OK",
"continue", or "sounds good" is insufficient. If scope changes at all, previous
confirmation is invalid and fresh confirmation is required.

## Anti-Entropy Declaration

Before deletion, state:

```text
Anti-Entropy Declaration:
- Deletion Class:
- Old Path/Object:
- Invalid Responsibility / Authority:
- Legitimate Capability Remaining on Carrier:
- New Canonical Owner:
- Expected Preserved Behavior:
- Expected Retired Behavior:
- External Boundary Touched: no | yes
- Source-of-Truth Data Risk: none | possible | confirmed
- User Confirmation Required: no | yes
```

For external-unknown code, fill `User Confirmation Required` with `yes` unless
the user's own instruction already names the concrete external risk, accepts
its possible breakage, and authorizes the exact retirement scope, or the user
later gives scoped confirmation after your disclosure. A generic original
deletion request does not satisfy this slot. Do not infer acceptance from mere
awareness of external use or from your own risk summary.

If `User Confirmation Required: yes`, stop normal delete-first flow.
Persistent-state or irreversible targets enter `Data Destruction Guard`;
external-unknown code stays in the `Retirement Decision` hold below.

## Retirement Decision

Choose one path only:

```text
Retirement Decision:
- Path: delete-first | compat-exception | confirmation-first
- Why:
- Non-edits:
```

Rules:

- choose `delete-first` for internal retirement unless a stronger boundary blocks it
- choose `compat-exception` only when external dependency is proven
- choose `confirmation-first` for irreversible targets or proven distribution
  whose consumers cannot be observed

If `Path = confirmation-first`, no destructive execution may happen until
scoped confirmation is established. For external-unknown code, earlier generic
deletion instructions do not count. An informed, scoped user instruction may
establish confirmation before your disclosure; otherwise disclose the risk
and directly ask the user to confirm the exact retirement scope before editing.
Do not only state that confirmation is required or quote the words needed.

## Verification Plan

Do not verify only by "tests are green". Verify that the old logic actually
died and the new owner actually carries the behavior.

```text
Verification Plan:
- Main-path check:
- Lingering-reference check:
- Negative check:
- Boundary check:
```

Meaning:

- `Main-path check`: new canonical owner still satisfies intended behavior
- `Lingering-reference check`: the retired responsibility is no longer active;
  when its carrier was deleted, the old path is no longer referenced on the
  main path
- `Negative check`: retired trigger/path really stopped working
- `Boundary check`: host/API/schema/persistence boundary was not accidentally broken

## Gap Taxonomy

If a gap appears after deletion, classify it before repairing:

- `expected-retirement`
- `missing-owner-logic`
- `stale-internal-consumer`
- `baseline-gap`
- `external-compat`
- `persistent-state-risk`

`persistent-state-risk` is a stop condition, not a normal repair branch.

## Gap Closure

Repair order:

- `expected-retirement`
  - update tests, docs, or caller expectations
- `missing-owner-logic`
  - fix the new canonical owner
- `stale-internal-consumer`
  - migrate the internal consumer
- `baseline-gap`
  - correct requirement / spec / baseline first
- `external-compat`
  - allow compat only if active external dependency evidence exists
- `persistent-state-risk`
  - stop and ask for user confirmation

Use this contract:

```text
Gap Closure:
- Gap Found:
- Gap Type:
- Repair Action:
- Reintroduced Compat: no | yes
- If yes, External Dependency Evidence:
- Retirement Trigger:
```

If `Gap Type = persistent-state-risk`, stop and return to the confirmation
gate. Do not improvise destructive repair.

## Compat Exception Gate

Retention is allowed only if all are true:

- an external boundary is touched
- current active dependency evidence exists
- deletion would break a published or documented contract
- the current slice cannot complete owner repair or consumer migration
- an observation metric exists
- a retirement trigger exists

Without these, do not retain compat.

## Completion Semantics

Completion claims must reflect the real outcome:

- internal retirement with old compat preserved -> `bounded mitigation` or
  `deferred debt`, not clean retirement
- external compat retained with full evidence -> `bounded compatibility exception`
- persistent-state deletion without scoped confirmation -> not complete

## Common Mistakes

Do not:

- treat unknown dependency as proof of dependency
- treat missing active-dependency evidence as proof that deletion is safe across
  a proven external boundary
- keep both owners active "for safety"
- add a fallback before checking whether the gap belongs in the new owner
- confuse migration-file deletion with live database deletion
- treat source-of-truth data cleanup as ordinary code retirement
- call a task "cleaned up" when old logic still carries main-path behavior
- delete a carrier merely because one authority on it was invalid when a
  separately evidenced legitimate role remains
- treat a warning or guard card as destructive authorization

## Minimal Reporting Shape

This shape is the anti-entropy workflow's decision surface, not a separate
final completion report. When anti-entropy materially shapes a completed task,
its preserved/retired behavior, deletion class, retained boundary, verification
plan, and residual risk should flow into `verification-before-completion`'s
unified Aegis impact/safety receipt.

```text
Aegis Visibility:
Anti-Entropy Declaration:
Retirement Decision:
Verification Plan:
Gap Closure:
```

Use the compact shape by default. Expand only when task risk requires it.