# Ddd When To Wrap Primitives

> Use when deciding whether a primitive value should become a domain-specific type or value object. Balances primitive obsession against value-object obsession using risk, invariants, behavior, and cost. Trigger for wrapping strings/ints/UUIDs, value object decisions, too many tiny types, or whether a primitive is good enough.

- Skill: `amadeus-dlc/ddd-when-to-wrap-primitives` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add amadeus-dlc/ddd-when-to-wrap-primitives`
- Raw SKILL.md: https://api.skillmd.com/api/skills/amadeus-dlc/ddd-when-to-wrap-primitives/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: amadeus-dlc (https://skillmd.com/u/amadeus-dlc)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/amadeus-dlc/ddd-when-to-wrap-primitives

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# When To Wrap Primitives

Wrap primitives when the wrapper changes correctness, not when it only signals virtue.

## Wrap When

- The value has a domain name and invariant.

- Two values of the same primitive type can be confused.

- Validation is repeated or easy to forget.

- Behavior naturally belongs with the value.

- Invalid states cause meaningful business risk.

## Do Not Wrap Yet When

- The value has no behavior or invariant.

- The wrapper would only forward primitive operations.

- The type is local, temporary, or purely technical.

- The team would pay high ceremony for little safety.

## Workflow

1. List candidate primitives and their risks.

2. Score invariant strength, misuse risk, behavior, reuse, and migration cost.

3. Wrap the highest-value candidates first.

4. Keep construction explicit and error reporting useful.

## Detailed Reference

For non-trivial implementation, review, or refactoring work, read `references/details.md` before giving final guidance. It contains the detailed rules, examples, smells, and migration notes that do not belong in the short invocation body.

## Output

Return a wrap/keep table with rationale and example APIs for the chosen wrappers.