typescript-configs

name	typescript-configs
description	Use when TypeScript work involves env values, config parsing, contextual config objects, config defaults, validation boundaries, or migration from legacy config reads.

TypeScript Configs

Use this skill when unknown runtime values become typed application configuration.

Application Shape Model

Config shape depends on app scale and framework pressure:

Application nature	Start with
Simple script, single file, usually one maintainer	One small manual parser and one local config object is fine
Medium app, multiple files/features, one person to small team	Contextual feature/module configs such as EmailConfig, BillingConfig, StorageConfig
Large app, many modules/features, one or more teams	Root parsing plus module config factories; pass only contextual configs inward
Framework-shaped app, such as Next.js, React Native/Expo, NestJS	Respect the framework's config/composition entrypoints, then project contextual configs at module/feature boundaries

Default for non-trivial apps: avoid a god AppConfig flowing everywhere. Parse raw values at the boundary, then project the smallest contextual config each module needs. Framework conventions decide where parsing/assembly starts; they do not require feature modules to consume unrelated config.

Agent Quick Path

If you see...	Read
process.env, raw config strings, !, as, untyped config	rules/parse-and-expose-config.md
broad AppConfig passed into feature modules or tests	rules/contextual-config.md
schema does network/file/cloud checks	rules/validation-vs-verification.md
default value, fallback, dev default, global config owner question, production-safe behavior tuning	rules/defaults-and-ownership.md
URL, host, IP, endpoint, token, credential, secret-bearing fallback	../typescript-security/rules/secrets-lifecycle.md
feature flag, mode, stage-derived behavior decision, repeated raw flag check	rules/feature-decisions.md
legacy env reads or risky config refactor	rules/migration.md

Owns

• Parsing unknown config into typed contextual objects.
• Deciding simple/local/module/root config shape by application scale.
• Requiredness, production-safe defaults, and config ownership.
• Separation of shape validation from external dependency verification.
• Feature flags and modes parsed into named behavior decisions.
• Migration from scattered env reads.

Does Not Own

• Secret value fetching and redaction: use ../typescript-security/SKILL.md.
• Dependency construction from config: use ../typescript-composition/SKILL.md.
• Config contract tests: use ../typescript-testing/SKILL.md.

Default

Parse unknown values once at the boundary. Pass contextual typed config inward. If a missing value would not be production-correct, require it. Keep app-wide config only for app-wide facts, and keep dependency verification separate from parsing.