book-legacy-change-safety skillA
book-legacy-change-safety is agent-read markdown (skill) from kunolu/640-skills: Guides safe changes to legacy or weakly tested code by characterizing behavior before editing. In strict tasks, mandatory before the first behavior-changing edit for existing-behavior bug fixes or existing code with unclear behavior, low coverage, hidden dependencies, or high regression risk; in default/lite tasks, use on demand when those risks or explicit delivery requirements are present..
Indexed from public GitHub and served as immutable, content-addressed versions. Install it pinned to an exact SHA-256 with the mdr CLI, and every file is verified against the hash recorded here before it reaches your agent. The deterministic audit below grades the latest version, and the same file always earns the same grade.
What the file says
# Book Legacy Change Safety Use this Skill when the main risk is not the requested change itself, but the uncertainty around existing behavior. It is derived from the `mini` rule style of `agent-rules-books` and is intended to complement `diagnosing-bugs`, `tdd`, source/LSP/contract impact analysis, and project validation. ## Strict Development Gate In a strict task, run this Skill before the first behavior-changing edit when either condition is true: - The task fixes a bug in existing observable behavior. - Existing target code has weak / missing tests, unclear or undocumented behavior, hidden dependencies, or high regression risk. Emit a separate visible review: ```text Legacy Change Safety Review Status: characterized | needs-safety-net | seam-required | blocked Behavior to change: ... Behavior to preserve: ... Current reproduction evidence: ... Safety net: ... Hidden dependencies / seam: ... Validation plan: ... Review mode: normal | safety-seam-only ``` - `characterized`: current behavior was reproduced or otherwise established, preserved behavior is explicit, and an adequate safety net exists. …
Read the whole file at its exact version.
How to install
mdr add kunolu/640-skills/book-legacy-change-safety@git:20260920.f9bbb90mdr add kunolu/640-skills/book-legacy-change-safety@sha256:b10f27a3b32718bfPin to a label to follow the author's releases, or to a sha256 to freeze the exact bytes forever. Either way the resolved hash is written to mdr.lock, and mdr install reproduces it on any machine.
[](https://markdownregistry.com/a/art_v5lrt36hem6dk35v)
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Versions
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260920.f9bbb90 latest | 2026-09-20 | f9bbb90 | 4,578 B | A | view · diff |
| git:20260719.6349540 | 2026-07-19 | 6349540 | 4,356 B | A | view · diff |
| git:20260718.951ea5b | 2026-07-18 | 951ea5b | 2,003 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (4578 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
kunolu/640-skills · 113 stars · license Apache-2.0 · pushed 2026-09-25 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_v5lrt36hem6dk35v GET https://markdownregistry.com/api/v1/resolve?ref=kunolu/640-skills/book-legacy-change-safety GET https://markdownregistry.com/api/v1/blob/b10f27a3b32718bf4b84591746fe9206adf1242fed2608eb01e3f1fe30031392
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