This file is byte-identical to the first copy the registry indexed, one of 3 indexed copies. Same content hash, so the same checks give both the same grade.
principle-migrate-callers-then-delete-legacy-apis from backnotprop/pstack is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
Apply when introducing a new internal API while old callers still exist. Migrate callers and delete the old API in the same wave instead of preserving compatibility layers.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Migrate Callers Then Delete Legacy APIs
- Update tests to assert the new contract, and delete tests that only protect pre-refactor implementation details
**When this applies:**
- No external users depend on backward compatibility
- The project can absorb coordinated breaking changes
- The new API is part of a simplification or refactor initiative
The line at the top of this page pins the label git:20261019.6ddf66a, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.
pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (637 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
GitHub
backnotprop/pstack · 3,337 stars · license MIT · pushed 2026-10-28 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_letfoatp45wczxu7
GET https://markdownregistry.com/api/v1/resolve?ref=backnotprop/pstack/principle-migrate-callers-then-delete-legacy-apis
GET https://markdownregistry.com/api/v1/blob/580ad9bb1a0994ecb924321ba49efc38a2f85c64e22c76fb133f57a78272a2e6
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