Type System Discipline

Portability (required)

This skill is part of the portable pstack pack.

1. Read the pstack capability contract and the adapter for the active coding agent before any helper delegation.
2. Prefer capability verbs (explore, implement, review, parallel, ask_user, verify, model_role) over vendor tool names.
3. Resolve models through model_role. Never require a vendor-specific model identifier.
4. When helper spawning is unavailable, run the work on the lead agent and state that fan-out was collapsed.

The type checker is a proof assistant. Use it to eliminate impossible states, mismatched primitives, and unhandled variants at compile time. A case the types let you ignore becomes a runtime failure the compiler could have stopped. Prefer defining errors and special cases out of existence over proliferating handlers; unrepresentable states, total functions, and interface redesign (the patterns below) are the tools.

Applies to any typed language. Skills like typescript-best-practices ground it in specific syntax.

The patterns: