| name | nw-ddd-architect |
| description | DDD architect design-time mandates — the Fixture-Fanout Enumeration Mandate for shared-substrate per-caller migration (enumerate production callers plus fixture sites plus atomic bundle scope, mechanically enforced) that both the ddd-architect and its reviewer load by name |
| user-invocable | false |
| disable-model-invocation | true |
DDD Architect — design-time mandates
The nw-ddd-architect agent and nw-ddd-architect-reviewer both instruct loading this file
by name (~/.claude/skills/nw-ddd-architect/SKILL.md) at DESIGN entry, before any DESIGN row
is authored. It carries the design-time mandates that must be in context BEFORE the domain
model is authored. Strategic/tactical/event-modeling knowledge lives in the sibling skills
(nw-ddd-strategic, nw-ddd-tactical, nw-ddd-event-modeling, nw-ddd-eventsourcing); this
core holds the cross-cutting enforcement mandates the agent spec references.
Fixture-Fanout Enumeration Mandate
F-DDD-ARCHITECT-SKILL-FIXTURE-FANOUT-GATE (M51 R-M51-B closure, 2026-05-25) — a
mechanically-enforced design-time gate.
When it fires. A DESIGN row that migrates a shared substrate per-caller — an adapter /
ledger / plugin whose construction or seed surface is shared between production and test
composition. Trigger by either signal:
- the row's
Decision = PER_CALLER_MIGRATION, OR
- the substrate type matches the pattern
[A-Z]\w+Ledger | [A-Z]\w+Adapter | [A-Z]\w+Plugin
AND is constructed in BOTH src/ and tests/ (for example, a shared persistence adapter).
What the row MUST enumerate (with grep evidence). Three cells, all mandatory:
- (a) Production Callers — every production callsite,
file:line for each.
- (b) Fixture Sites — every test-composition / helper /
conftest entry that CONSTRUCTS or
SEEDS the same substrate. This is the cell that is silently omitted — and its omission is the
M50 defect class: the substrate ships GREEN against its own ATs and breaks sibling consumers
at the crafter's empirical run.
- (c) Atomic Bundle Scope — the row explicitly states
production sites {N} + fixture sites {M} ship together in slice {S}. Production sites + fixture sites that read/write the SAME
substrate path MUST ship in ONE slice; splitting them across slices is the violation.
Why (empirical anchors). friction #42 F-M40-SLICE-02C-N1-PRODUCTION-FIXTURE-NOT-ATOMIC
(M50 crafter — 3 production callsites declared, 5+ fixture sites silently excluded → 12 sibling
regressions, REVERTED). A 5-instance META-pattern (#33 M34 + #38 M42 + #40 M45 + #42 M50 + #43
M49) all surfaced ONLY at the crafter's empirical execution despite architect residuality
passes — the Streetlight bias: M50 declared 7 sites where empirical run found 18 (2.5× undercount).
The eye does not see the fixture fanout; the mechanical grep does.
Mechanical procedure + rejection rule (self-execution; the reviewer runs the same).
- grep the DESIGN section for rows matching the substrate-migration trigger above.
- For each, extract the
Production Callers: count + Fixture Sites: count + Atomic Bundle:
cell.
- Run INDEPENDENT grep counts against the real tree:
- production:
grep -rn '<substrate_pattern>' src/des/ | wc -l
- fixtures:
grep -rln '<substrate_pattern>' tests/ | xargs grep -c '<substrate_pattern>' | awk -F: '{s+=$2} END {print s}'
- REJECT (critical BLOCKER) on ANY of: a missing cell (Production Callers / Fixture Sites /
Atomic Bundle Scope), a declared-vs-empirical count mismatch (off-by-N% for any N > 0), or an
Atomic Bundle that splits production from fixtures across slices. A row that lists production
callers but omits the fixture-sites enumeration is the silent-fixture-fanout defect — block it.
Defense-in-depth. Complements F-D-09 (Forbidden-Import-Roots) + the runtime cascade-detector
arch test (registry-vs-frozenset symmetry). The architect declares the enumeration (principle 9);
the reviewer re-runs the greps and blocks on mismatch (principle 6); neither trusts the other's
count — the grep is the arbiter.
