cellar: Instructions file for Claude Code

Important tools

1. Cellar

When you need the API of a JVM dependency, always use cellar. Use it before metals-mcp.

Project-aware commands (run from project root)

For querying the current project's code and dependencies (auto-detects build tool):

cellar get [--module <name>] <fqn>       # single symbol
cellar list [--module <name>] <package>  # explore a package
cellar search [--module <name>] <query>  # find by name

• Mill/sbt projects: --module is required (e.g. --module lib, --module core)
• scala-cli projects: --module is not supported (omit it)
• --test: query the test-scope classpath (sbt/scala-cli; for Mill, use the test module directly, e.g. --module foo.test)
• --no-cache: skip classpath cache, re-extract from build tool
• --java-home: override JRE classpath

External commands (query arbitrary Maven coordinates)

For querying any published artifact by explicit coordinate:

cellar get-external <coordinate> <fqn>       # single symbol
cellar list-external <coordinate> <package>  # explore a package
cellar search-external <coordinate> <query>  # find by name
cellar deps <coordinate>                     # dependency tree

Coordinates must be explicit: group:artifact_3:version

Development Principles

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

Before implementing:

State your assumptions explicitly. If uncertain, ask.
If multiple interpretations exist, present them - don't pick silently.
If a simpler approach exists, say so. Push back when warranted.
If something is unclear, stop. Name what's confusing. Ask.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

No features beyond what was asked.
No abstractions for single-use code.
No "flexibility" or "configurability" that wasn't requested.
No error handling for impossible scenarios.
If you write 200 lines and it could be 50, rewrite it.

Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.