DDD Tactical Lens — Right Pattern, Correct Aggregates

Decide and review the tactical design of code through the lenses from Learning Domain-Driven Design (Vlad Khononov, O'Reilly), Parts II–III. This is not a generic layering/cohesion check (use model-lens) and not a bug hunt (use code-review). It asks two questions:

1. Is this the right business-logic pattern for this subdomain? (decision tree)
2. If it's a domain model, do the aggregates and value objects actually hold their invariants and publish events safely? (correctness rules)

Apply the relevant lenses, report findings grouped by lens, cite file:line, name the rule, propose the fix. Skip lenses that don't apply rather than padding. If it's clean, say so plainly.

First: classify the subdomain

Pattern choice follows from subdomain type. Before recommending, place the work: