| name | add-domain-entity |
| description | Add a domain entity, aggregate, or value object to the .NET API — rich mutable class with private ctor + static factory (UUIDv7), invariants that throw, tenant_id, identity equality; records for value objects. Use when modeling new domain state under apps/api/{{ProjectName}}.Domain. |
| argument-hint | <Feature>/<TypeName> |
| allowed-tools | Read, Glob, Grep, Bash, Skill, mcp__serena__initial_instructions, mcp__serena__get_symbols_overview, mcp__serena__find_symbol, mcp__serena__find_referencing_symbols, mcp__serena__find_declaration, mcp__serena__find_implementations, mcp__serena__search_for_pattern, mcp__serena__get_diagnostics_for_file, mcp__serena__list_dir, mcp__serena__find_file, mcp__serena__create_text_file, mcp__serena__replace_symbol_body, mcp__serena__insert_after_symbol, mcp__serena__insert_before_symbol, mcp__serena__replace_content, mcp__serena__rename_symbol, mcp__serena__safe_delete_symbol |
Serena MCP is mandatory for C# code. First call mcp__serena__initial_instructions to load the Serena tool manual, then use the Serena tools for ALL .cs reading / searching / navigation / creation / editing — prefer symbol navigation (get_symbols_overview / find_symbol / find_referencing_symbols) over whole-file reads. Native Edit/Write on .cs is hook-blocked (the TS/React frontend uses the native tools).
Add a domain entity / value object
The procedure for our rich, base-class-free DDD model. Source of truth (the facts — read them):
.claude/rules/backend/domain-model.md and docs/projectStandards/coding-standards.md. The domain is
persistence-ignorant (no EF types/navigations). C# (.cs) edits via Serena.
Entity / aggregate
- Place in
{{ProjectName}}.Domain/<Feature>.
- Rich mutable class (NEVER a record). Shape:
- a private parameterless constructor (EF materialization);
- a
public static Create(...) (or named) factory with guard clauses that throws on invalid input and
mints the id via Guid.CreateVersion7() (never Guid.NewGuid() / Guid.Empty-until-save);
- all setters private — state changes only through behaviour methods;
- invariants enforced inside every behaviour method (throw on violation — the domain is the last line of
defence);
- a non-null
TenantId preserved across mutations (the tenancy invariant);
- identity-based equality declared on the type itself (no base
Entity/AggregateRoot, no domain events).
- No primary constructors.
Value object
- A record (or
readonly record struct) — immutable, value equality (e.g. Money, ModelId, TenantId).
After
- EF mapping (config) and repository → the
efcore-patterns skill. Build (dotnet build, warnings = errors).
- Tests (factory guards, invariant throws, behaviour) → the
write-tests skill, per the plan's exact test list.
