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.
npx skills add necoz-oss/is-kit --skill learngit clone --depth 1 https://github.com/necoz-oss/is-kitWrote 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.
[](https://agentmods.dev/skills/necoz-oss/is-kit/learn)<a href="https://agentmods.dev/skills/necoz-oss/is-kit/learn"><img src="https://agentmods.dev/badge/skills/necoz-oss/is-kit/learn/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.
<a href="https://agentmods.dev/skills/necoz-oss/is-kit/learn"><img src="https://agentmods.dev/badge/skills/necoz-oss/is-kit/learn.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 5.1 | $0.00038 | $0.00976 |
| Opus 5.5 | $0.00015 | $0.00390 |
| Sonnet 5.5 | $0.00008 | $0.00195 |
| Haiku 4.5 | $0.00004 | $0.00098 |
Grade A, and why
learn 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 5d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- learn — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 152 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/learn - Capture Reusable is-kit Patterns
Analyze the current session and capture reusable knowledge for this TypeScript type-guard library.
Auto-Activation Criteria
Consider auto-activating this skill when:
- A non-trivial bug was fixed in runtime guard behavior or type inference.
- A public API design decision was made and validated with tests.
- A tricky TypeScript modeling pattern was discovered.
- A runtime/type parity issue was diagnosed and resolved.
- The session produced reusable guidance about tests, docs, or release safety for this library.
Do not activate for:
- trivial typo fixes
- one-line doc wording changes
- obvious refactors with no reusable lesson
- patterns already documented in
.codex/skills/learn/learned/
Manual Trigger
Run /learn after finishing a meaningful implementation, refactor, or debugging session in is-kit.
What To Extract
1. Public API Design Patterns
- What API was added or changed?
- Why was that shape chosen over alternatives?
- What backward-compatibility constraint mattered?
- How should similar future APIs be designed?
Project-relevant examples:
- Distinguishing key-level optionality from value-level
undefined. - Choosing a specialized combinator vs. a more generic abstraction.
- Preserving existing semantics in a minor release while introducing a new helper.
2. Type Modeling Patterns
- How were inference, narrowing, or overloads preserved?
- What TypeScript limitation mattered?
- What exact type shape or helper solved it?
Project-relevant examples:
- Modeling
structschemas with required vs. optional keys. - Normalizing intersection-heavy inferred types for
tsd. - Preserving literal narrowing without assertion casts.
3. Runtime Validation Patterns
- What runtime behavior needed to match the type-level contract?
- What edge cases mattered?
- What implementation detail should future changes preserve?
Project-relevant examples:
- Own-key checks vs. inherited property checks in
struct. - Exact-mode semantics when optional keys are present or absent.
- Composing schema markers with existing value guards.
What ships with it
13 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- LEARNED_INDEX.md 2.8 KB
- learned/balance-runtime-cost-with-compositional-design.md 2.2 KB
- learned/deprecate-public-api-before-major-removal.md 2.7 KB
- learned/keep-typed-schema-key-coverage-explicit.md 3.7 KB
- learned/model-transformations-as-decoders.md 3.1 KB
- learned/order-precise-overloads-before-generic-fallbacks.md 2.7 KB
- learned/prefer-non-throwing-intrinsic-brand-checks.md 2.3 KB
- learned/preserve-enumerable-key-membership-in-exact-structs.md 3.8 KB
- learned/preserve-explicit-generic-call-compatibility.md 2.6 KB
- learned/preserve-type-guard-semantics-across-host-values.md 1.9 KB
- learned/require-singleton-keys-for-single-property-refinements.md 3.9 KB
- learned/separate-property-refinement-absence-contracts.md 3.9 KB
- learned/test-packed-artifacts-from-a-consumer-project.md 3.3 KB
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.
- 5d ago First seen · 152 lines · 38 tokens per session scan A db362ac51fc4
learn is a skill published in the GitHub repository necoz-oss/is-kit (163 stars, last pushed today), licensed MIT. It adds 38 tokens to every session and 976 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-11-01.
Other skills, from other repositories
use-is-kit
Create, compose, migrate, and review TypeScript runtime type guards with is-kit. Use when adding reusable guards; replacing typeof, null checks, or handwritten type predicates; narrowing unknown values; validating JSON or API responses; building collection or object schemas with struct or typedStruct; or reviewing…
learn
Extract reusable patterns from non-trivial work in the is-kit repository and store them as project knowledge. Use after meaningful API design, type-system work, debugging, or compatibility discoveries.
prettier-format
Run Prettier for the is-kit repository. Use when asked to format or check formatting in this project. Always consult AGENTS.md in the repo root before executing commands.
ax-cpp-agent-memory-skills
Use when writing C++ code with axllm for agent memory, recall callbacks, dynamic skill discovery, loaded-skill state, and used-skill tracking.
ax-cpp-agent-context
Use when writing C++ code with axllm for deciding between context maps, trajectory context policy, offline optimization (ACE/GEPA), and memory recall for long-context agents.
write-script-bun
MUST use when writing TypeScript scripts. Bun is the default and preferred TypeScript runtime — pick it for TypeScript unless the script specifically needs Deno.