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 agentmods add skills/xobotyi/cc-foundry/typescriptnpx skills add xobotyi/cc-foundry --skill typescriptgit clone --depth 1 https://github.com/xobotyi/cc-foundryWhat 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 | $0.00060 | $0.03179 |
| Opus 5 | $0.00030 | $0.01589 |
| Sonnet 5 | $0.00012 | $0.00636 |
| Haiku 4.5 | $0.00006 | $0.00318 |
Grade B, and why
typescript scanned grade B with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Strips warnings and disclaimersmediumAnti-refusal
Omitting safety caveats hides risk from the user and is a common jailbreak preamble.
- Don't lecture — state what's wrong and how to fix it. How it starts
The opening of the file, as written. The whole thing — 245 lines — stays where its author put it; the contents beside it link to each section on GitHub.
TypeScript
Types encode intent. Let the compiler prove the rest.
TypeScript's value is in catching bugs at compile time. Write types that express your domain; let inference handle the
obvious. Never fight the type system — if you need as or any, the types are wrong.
References
| Topic | Reference | Contents |
|---|---|---|
| Generics, utility types, type-level programming | [${CLAUDE_SKILL_DIR}/references/generics.md] |
Utility type tables, conditional/mapped type examples, infer, template literals |
| Narrowing, type guards, discriminated unions | [${CLAUDE_SKILL_DIR}/references/narrowing.md] |
typeof/instanceof/in examples, exhaustive switch, type predicates, assertion fns |
| tsconfig options, module resolution, project setup | [${CLAUDE_SKILL_DIR}/references/configuration.md] |
Base/strict/module configs, library setup, compiler directives, project structure |
| Branded types, overloads, class patterns, enums | [${CLAUDE_SKILL_DIR}/references/patterns.md] |
Interface vs type examples, assertion patterns, enum anti-patterns, callback types |
Type Safety
strict: truealways. No exceptions. It enablesstrictNullChecks,noImplicitAny,strictFunctionTypes, and other critical checks.unknownoverany. Useunknownand narrow with type guards.anydisables type checking entirely. Reserveanyfor migration or test mocks only — document why.- No non-null assertions (
!) without justification. Prefer narrowing. If!is truly needed, annotate it with the reason the value cannot be null. - No type assertions (
as) for object literals. Use type annotations (: Foo) instead — assertions hide missing/extra property errors.
What ships with it
5 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.
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.
- 3d ago First seen · 245 lines · 60 tokens per session scan B d5f69f181266
typescript is a skill published in the GitHub repository xobotyi/cc-foundry (20 stars, last pushed 3d ago), licensed MIT. It adds 60 tokens to every session and 3,179 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 1 finding (strips warnings and disclaimers). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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