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 chhoumann/t3-pstack --skill typescript-best-practicesgit clone --depth 1 https://github.com/chhoumann/t3-pstackWrote 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/chhoumann/t3-pstack/typescript-best-practices)<a href="https://agentmods.dev/skills/chhoumann/t3-pstack/typescript-best-practices"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/typescript-best-practices/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/chhoumann/t3-pstack/typescript-best-practices"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/typescript-best-practices.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 | $0.00024 | $0.00655 |
| Opus 5.5 | $0.00010 | $0.00262 |
| Sonnet 5.5 | $0.00005 | $0.00131 |
| Haiku 4.5 | $0.00002 | $0.00065 |
Grade A, and why
typescript-best-practices 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.
This is a copy
84% identical to typescript-best-practices — 1 line 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.
What it actually says
TypeScript best practices
Apply the type-system-discipline principle skill first.
| Rule | Summary |
|---|---|
| Discriminated unions | Model variants with a kind literal discriminant so impossible states can't be represented. No optional-field bags. |
| Branded types | Brand primitives with & { readonly __brand: "X" } so they can't be mixed up. Validate once at the boundary. |
| Constructive modeling | Build the shape so the illegal value can't be constructed. [T, ...T[]] for non-empty, [T, T][] for even length, start plus duration for a range. Not a runtime guard, not a wish for refinement types. |
| Simplest total type | Keep T[] while every operation on it stays total. Strengthen to NonEmpty<T> only where the loose type forces !, a cast, or a "should never happen" throw. |
unknown over any |
External data is unknown. |
| Schemas before guards | Before hand-writing a property-by-property type guard, use the repository's runtime schema library and infer the type from the schema, such as z.infer. |
No as casts |
Every as is a runtime crash waiting. Cast only after validation. |
| Narrowing hierarchy | Discriminant switch > in operator > typeof/instanceof > user-defined type guard > as. |
| Type guards | Must verify the claim. A lying guard is worse than as because the bug hides behind a name that says it's safe. Name them isX or hasX. |
| Exhaustiveness | Inline const _exhaustive: never = x; in default arms so the compiler errors when a new variant is added. |
satisfies over as |
Validates the value without widening literal types. |
| Boundary validation | Parse where data crosses in, into a named domain type. Record<string, unknown> (however spelled) stops at that parse. Trust types inside. See the boundary-discipline principle skill. |
| Schema-derived types | Reach for Pick/Omit/Parameters/ReturnType/Awaited/typeof before declaring a new interface. |
| Object args | Pass objects, not positional, so argument order is self-documenting. Skip on hot paths (per-frame render, tokenizers, parsers). |
| Real tests | Don't mock what you can run. Prefer the framework's real test primitives with leak/disposable checks, and verify UI in a running build. Mock only what you can't run locally. |
| Structured telemetry | Prefer structured logger diagnostics with enough context to debug from an id. No console.log in shipped code. |
Examples: references/patterns.md.
What ships with it
1 file 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.
- yesterday Changed · +1 lines 28f9e61710e2
- 3d ago First seen · 31 lines · 24 tokens per session scan A fd61fe218e2d
typescript-best-practices is a skill published in the GitHub repository chhoumann/t3-pstack (190 stars, last pushed yesterday), licensed MIT. It adds 24 tokens to every session and 655 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 84% identical to typescript-best-practices, differing in 1 line, and is treated as a copy.
Other skills, from other repositories
no-bare-casts
Writing as in TypeScript or TSX production code, modifying a file that contains a bare as cast, silencing a type error with a cast, encountering as unknown as, or reviewing a cast site.
aws-sst-development
SST v4 (Ion) expert for managing AWS resources as code with the Pulumi-backed framework.
league-akari-shard-development
Use when creating, extending, refactoring, splitting, or reviewing League Akari main or renderer shards, including shard file organization, controller/loader/executor/handler boundaries, naming conventions, renderer TSX usage, platform guards, and public contract compatibility.
dd-code-generation
Use pup CLI for immediate Datadog operations or generate code for integration into applications.
fast-typescript-check
Keep www-sacred's TypeScript fast to type-check and fast to run. Use when touching the ASCII/canvas animation components (the only real per-frame code here), tightening type-check wall-clock, or auditing a change for runtime or compiler regressions. Scoped to this repo — a React 19 / Next.js 16 component library plus…
typescript-magician
Designs complex generic types, refactors any types to strict alternatives, creates type guards and utility types, and resolves TypeScript compiler errors. Use when the user asks about TypeScript (TS) types, generics, type inference, type guards, removing any types, strict typing, type errors, infer, extends…