principle-migrate-callers-then-delete-legacy-apis

principle-migrate-callers-then-delete-legacy-apis is a skill for Claude Code from chhoumann/t3-pstack. It costs 45 tokens per session (229 once invoked), scanned A, a copy of principle-migrate-callers-then-delete-legacy-apis, MIT.

A refactoring rule for replacing an internal API: move all internal callers to the new interface, then remove the old one in the same change. An API is the defined way that software components call each other.

In plain words
What is it for?
Use it during coordinated internal API changes when there are no outside users who need the old interface. Update tests to check the new contract and remove tests for deleted implementation details.
Why use it?
It avoids maintaining two paths and prevents temporary compatibility code from becoming permanent complexity.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

Part of the t3-pstack plugin — 62 skills, 4 agents, 1 hook shipped together

Good fit Use it during coordinated internal API changes when there are no outside users who need the old interface. Update tests to check the new contract and remove tests for deleted implementation details.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/chhoumann/t3-pstack/principle-migrate-callers-then-delete-legacy-apis
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add chhoumann/t3-pstack --skill principle-migrate-callers-then-delete-legacy-apis
Clone the repo
git clone --depth 1 https://github.com/chhoumann/t3-pstack

Made for: Claude Code.

Or install t3-pstack, the plugin that ships this one along with the rest of its 62 skills, 4 agents, 1 hook.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for principle-migrate-callers-then-delete-legacy-apis

README.md
[![agentmods](https://agentmods.dev/badge/skills/chhoumann/t3-pstack/principle-migrate-callers-then-delete-legacy-apis/github.svg)](https://agentmods.dev/skills/chhoumann/t3-pstack/principle-migrate-callers-then-delete-legacy-apis)
Your own site
<a href="https://agentmods.dev/skills/chhoumann/t3-pstack/principle-migrate-callers-then-delete-legacy-apis"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/principle-migrate-callers-then-delete-legacy-apis/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/chhoumann/t3-pstack/principle-migrate-callers-then-delete-legacy-apis"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/principle-migrate-callers-then-delete-legacy-apis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 229 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 91% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00045 $0.00229
Opus 5.5 $0.00018 $0.00092
Sonnet 5.5 $0.00009 $0.00046
Haiku 4.5 $0.00005 $0.00023

Measured yesterday against content hash 09978915a4a1, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

principle-migrate-callers-then-delete-legacy-apis scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

91% identical to principle-migrate-callers-then-delete-legacy-apis — 10 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/pstack/skills/principle-migrate-callers-then-delete-legacy-apis/SKILL.md · 23 lines

What it actually says

Migrate Callers Then Delete Legacy APIs

When we decide a new API is the right design, migrate callers and remove the old API in the same refactor wave instead of preserving compatibility layers.

Rule:

  • Do not keep legacy API paths only because internal callers still exist
  • Inventory callers, migrate them, and delete the old API immediately
  • Treat temporary adapters as exceptional and time-boxed, not default architecture
  • 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

Keeping both old and new APIs creates dual-path complexity, slows cleanup, and makes the codebase feel append-only.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday Changed 09978915a4a1
  2. 3d ago First seen · 23 lines · 45 tokens per session scan A 8014f4eb04fe

Subscribe to this mod's changes

principle-migrate-callers-then-delete-legacy-apis is a skill published in the GitHub repository chhoumann/t3-pstack (190 stars, last pushed yesterday), licensed MIT. It adds 45 tokens to every session and 229 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 91% identical to principle-migrate-callers-then-delete-legacy-apis, differing in 10 lines, and is treated as a copy.

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