typescript-advanced-type-guards SKILL.md skillA
typescript-advanced-type-guards from pantheon-org/tekhne is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add pantheon-org/tekhne/typescript-advanced-type-guards@git:20260923.7852cb4Pins git:20260923.7852cb4 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- pantheon-org/tekhne
- Path
skills/development/typescript-advanced/type-guards/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260923.7852cb4, committed Sep 23, 2026
- Size
- 8,372 bytes
- Repository stars
- 10
- License
- MIT
Runtime type guards, narrowing, and exhaustiveness checking for TypeScript — typeof/instanceof/in guards, custom and generic type predicates (value is T), discriminated union narrowing, assertion functions (asserts value is T), branded/nominal types validated at runtime, and exhaustive switch statements with a never guard. Use when replacing an unsafe `as` assertion with a real runtime check, fixing "Object is possibly undefined", modeling impossible states out of existence, writing an `is*`…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# TypeScript Type Guards Runtime type guards and narrowing: the compile-time type system backed by an actual runtime check, so a type guarantee is real rather than asserted. ## Mindset A type guard is a promise the compiler will hold you to only if the runtime check underneath it is honest. Never reach for `any` or an unchecked `as` assertion as a shortcut past a type error — both disable the exact safety net a guard exists to provide, and the error they suppress almost always points at a real design gap. Prefer narrowing a value before use over asserting its type after the fact: `if (typeof x !== "string") throw ...` gives the compiler a real fact to reason from; `x as string` gives it nothing but your word. Verify a narrowing actually narrows by re-running `tsc --noEmit` after the change — a guard that looks correct can still fail to narrow if its predicate doesn't match the shape TypeScript expects. Every union that models a real set of states deserves an exhaustive switch with a `never`-typed default branch, so adding a new state without updating every handler is a compile error, not a silent gap. ## When to Apply Use this skill when: …
Read the whole file at its exact version.
How to install
mdr add pantheon-org/tekhne/typescript-advanced-type-guards@sha256:e45d176a0cc31571The line at the top of this page pins the label git:20260923.7852cb4, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_tbd3xf2w7txp23ym)
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Versions
The registry has recorded 1 version of this file, committed on Sep 23, 2026.
Audit of the latest version
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- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
pantheon-org/tekhne · 10 stars · license MIT · pushed 2026-10-21 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_tbd3xf2w7txp23ym GET https://markdownregistry.com/api/v1/resolve?ref=pantheon-org/tekhne/typescript-advanced-type-guards GET https://markdownregistry.com/api/v1/blob/e45d176a0cc315714948fb12c9604698fa6499873e0aca4035a0cbf8e7ebb942
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.