kotlin-tech-index

A reference skill for ZCode / Claude that indexes Kotlin language features, standard-library APIs, compiler capabilities, and platform (JVM/Native/JS/Wasm/KMP) tooling — indexed by Kotlin version, and only the Stable/GA ones.

IRON LAW of this skill: never list Experimental / Beta / Preview / Alpha features as "ready-to-use" to the user. A capability is included in versions/*.md if and only if it is Stable/GA in that version — works out of the box, no @OptIn, no -X experimental flag.

Covers Kotlin 1.3 through 2.4.

What this skill is for

Trigger it whenever a user is starting or working in a Kotlin project and asks any version-specific question:

• "I'm on Kotlin 2.0, can I use Uuid?"
• "What's new in Kotlin 1.9?"
• "Which version added value class?"
• "I'm on 2.4.0 — list every language feature I can use."
• "How do I turn on context parameters? Which version introduced them?"

It triggers eagerly on any version-specific Kotlin question — even casual mentions like "I'm on 1.9, can I use value class?".

Design principles

1. Only Stable / GA is indexed. A capability's "home version" is the version where it became Stable — not where it was first introduced as Experimental.
2. Incremental files, accumulated view. Each versions/X.Y.Z.md lists only what's new and Stable relative to the previous version. To answer "what can I use in X?", the skill reads X and all earlier files, then removes deprecated items via references/deprecation-and-evolution.md.
3. Partial-Stable is explicitly annotated. When a feature is mostly Stable but has experimental subsets (e.g. kotlin.uuid.Uuid is Stable in 2.4.0 except V4/V7 generators), the exception is called out — never just labeled "Stable".
4. No kotlinx.* libraries. Only kotlin.* stdlib, the compiler, and platform toolchains. kotlinx.coroutines / serialization / datetime / Compose evolve independently of the language version.

Layout

SKILL.md                                  # Query workflow + Iron Law + self-check
versions/                                 # One file per Kotlin feature version
  1.3.0.md  ...  2.4.0.md
references/
  deprecation-and-evolution.md            # Deprecation map + Experimental→Stable tracker
  maintenance.md                          # Maintainer guide (writing/updating files)

Install — and you're done

This package is a skill (a markdown reference bundle), not a runtime library. Installing it copies the skill directly into your project's .claude/skills/ directory, so it's immediately usable — no manual copy step.

npm install kotlin-tech-index

What happens on install:

1. npm drops the package into node_modules/kotlin-tech-index/.
2. The postinstall hook runs init.js, which copies SKILL.md + versions/ + references/ into <project>/.claude/skills/kotlin-tech-index/.
3. Reload your agent — the skill is now available.

The installer is idempotent: re-running it (or upgrading the package) overwrites in place, so npm update kotlin-tech-index keeps the skill current.

Manual / npx invocation

If postinstall was skipped (e.g. --ignore-scripts, or pnpm/Yarn quirks), install the skill manually:

npx kotlin-tech-index              # copies into ./.claude/skills/
# or
node ./node_modules/kotlin-tech-index/init.js

Notes

• Project root resolution: the installer uses INIT_CWD (set by npm to the directory where npm install was invoked), falling back to npm_config_local_prefix, then process.cwd(). So npm install kotlin-tech-index from your project root always lands the skill in that project's .claude/skills/.
• No README/LICENSE/package.json in the skill dir — only the actual skill payload (SKILL.md, versions/, references/). Keeps the skills folder clean.

Data sources

Each versions/X.Y.Z.md cites its source URL at the top:

• Kotlin 1.3 – 2.4 official What's new pages: https://kotlinlang.org/docs/whatsnewXY.html

License

MIT © smartyu1993