A check for public programming-interface changes, including altered exports, their users, and the likely versioning impact.

Use it to compare changed files with a branch, classify changes as major, minor, or patch-level, and identify affected consumer files.

It shows whether a change could break other packages or applications before it is merged.

api-check — Skill by perilevy

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.

agentmods

npx agentmods add skills/perilevy/lsp-intelligence/api-check

Any agent

npx skills add perilevy/lsp-intelligence --skill api-check

Clone the repo

git clone --depth 1 https://github.com/perilevy/lsp-intelligence

Made for: Claude Code, Codex.

Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 290 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found 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.

Model	Per session	Once invoked
Fable 5	$0.00021	$0.00290
Opus 5	$0.00010	$0.00145
Sonnet 5	$0.00004	$0.00058
Haiku 4.5	$0.00002	$0.00029

Measured 2d ago against content hash 93c3cdbf2272, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-check 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 2d ago.

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.

skills/api-check/SKILL.md · 35 lines

What it actually says

API Guard

Check the public API surface for breaking changes before merging.

Steps

Parse the user's input:
- If --base <branch>: use that as the comparison base
- If --scope all: check all files, not just changed ones
- Default: changed files only, base auto-detected from main/master
Run api_guard with the parsed arguments
Present the result:
- Semver verdict: MAJOR (breaking), MINOR (additive), PATCH (internal)
- Breaking changes: list with structural diffs and consumer counts
- Risky changes: changes that might break consumers
- Safe changes: additive or internal-only
For each breaking change, highlight:
- What exactly changed (enum member added, param now required, etc.)
- How many cross-package consumers are affected
- Sample consumer files
If breaking changes exist:
- Suggest running /impact on the most impactful symbol
- Ask if the breaking change is intentional
- Offer to run /check on consumer files to verify they compile

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.

2d ago First seen · 35 lines · 0 tokens per session scan A 93c3cdbf2272

Subscribe to this mod's changes

api-check is a skill published in the GitHub repository perilevy/lsp-intelligence (1 stars, last pushed 4mo ago), licensed MIT. It adds 21 tokens to every session and 290 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Code review

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Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

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chat-perf

Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.

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