fix(domain-events): correct payload guidance — keep events serializable

[bradystroud]

1. What triggered this change? (PBI link, Email Subject, conversation + reason, etc)

While auditing a project's internal rules compare against SSW Rules, I noticed this rule advises "the entire Entity or Aggregate can be included since the event's scope is confined to the current bounded context."

We learned the hard way that this guidance doesn't hold up once an Outbox (or any async/persisted event handler) is introduced. Events holding an aggregate root fail to deserialize with System.NotSupportedException: Deserialization of types without a parameterless constructor... is not supported, because aggregate roots typically have factory methods, private set / init properties, and EF Core navigation properties. Events get stuck in the outbox and never publish.

The same problem affects event sourcing, audit replay, and promotion to Integration Events — anything that requires JSON serialization.

2. What was changed?

In public/uploads/rules/when-to-use-domain-and-integration-events/rule.mdx:

• Removed the inaccurate sentence claiming the full aggregate can be passed in a domain event.
• Added a new ## Event payloads — keep them serializable section with:
  • The three concrete reasons events need to serialize (Outbox, event sourcing, Integration Event promotion).
  • Bad/Good csharp examples — bad passes the aggregate, good passes flat primitives + IDs + enums-as-int.
  • A guidelines list: what to include, what to exclude, how to flatten value objects.
  • A short "Why not just pass the entity?" subsection — explains why this looks fine in-process but breaks the moment you bolt on anything async.

Bounded-context greybox kept; Integration Events section untouched; frontmatter unchanged (lastUpdated / lastUpdatedBy are system-managed).

Frontmatter validates clean via scripts/frontmatter-validator.

3. I paired or mob programmed with:

🤖 Drafted with Claude Code

[github-actions]

🔍 Preview PR Changes

View updated pages in edit mode:

• Do you know when to use Domain and Integration Events?

Branch: fix-domain-events-payload-guidance

[github-actions]

👋 Hi @bradystroud,

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[github-actions]

Howzit @bradystroud,

This PR has been here a while.

Did you know you should avoid merge debt?

1. Please action (e.g. get a review) and merge or close

Thanks!