Group the event store storage by Bounded Context

[alexander-yevsyukov]

This PR makes the event store of each Bounded Context land in its own physical
storage when the application runs on a storage backend which keys physical
storages by the record specification, such as jdbc-storage or gcloud-jvm.

Problem

All Bounded Contexts of an application share one StorageFactory.
DefaultEventStore created its record storage with no StorageGroup, and
its record specification is the same for every context (EventId → Event).
Backends deriving the physical storage identity from the specification alone
therefore put the events of all contexts into one table
(spine_core_Event in jdbc-storage) or one Datastore kind
(spine.core.Event in gcloud-jvm):

• events of all contexts (plus System contexts with persistEvents())
  intermingle in one physical store;
• CatchUpProcess reads via EventStore.read(..) filtered by event type —
  when two contexts share an event proto type, catch-up in one context replays
  the events of the other;
• there is no physical boundary for per-context data lifecycle.

InMemoryStorageFactory is unaffected only by accident: each
createRecordStorage(..) call returns a fresh, instance-isolated storage.
This is why tests never caught the issue.

Fix

DefaultEventStore now creates its record storage under a StorageGroup
named after the Bounded Context, via the new
StorageGroup.of(BoundedContextName) factory:

• StorageGroup's documented purpose is exactly this: differentiating
  storages holding records of the same type, so a vendor does not conflate
  them — per-entity histories already use it.
• Both group-honoring backends are fixed with no backend changes:
  jdbc-storage derives the Billing_Event table, gcloud-jvm the
  Billing-Event kind, through their existing grouped-naming paths.
• InMemoryStorageFactory ignores groups — no behavior change in tests.

The follow-up work in jdbc-storage and gcloud-jvm (custom-name /
custom-layout API for context-grouped storages, migration notes) is planned in
.agents/tasks/event-store-context-prefix.md
and will be addressed in separate PRs after this one lands.

Migration note (release notes material)

On group-honoring backends the event log moves to a new per-context physical
storage. Existing deployments keep their data in the old shared storage
(spine_core_Event / kind spine.core.Event); operators split it by the
type column/property using each context's event-type set. Detailed guidance
is part of the planned jdbc-storage / gcloud-jvm follow-ups.

Testing

• New EventStoreIdentitySpec asserts, at the createRecordStorage(..)
  vendor seam, that the event store arrives with the (group, recordType)
  identity (<context name>, Event), that two contexts produce two distinct
  identities, and that the group passes through SystemAwareStorageFactory
  intact.
• New StorageGroupSpec (a ClassTest) covers both of(..) factories and
  null-checks the static API.
• Full ./gradlew build dokkaGenerate passes locally, including the
  behavioral InMemoryDefaultEventStoreTest and the delivery/catch-up suites.

🤖 Generated with Claude Code

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[Copilot]

Pull request overview

This PR isolates DefaultEventStore persistence per Bounded Context by assigning the event store’s underlying record storage to a StorageGroup derived from the context name, preventing storage backends that key by record spec from conflating multiple contexts into a single physical store.

Changes:

• Pass a context-derived StorageGroup when creating the event store record storage in DefaultEventStore.
• Extend StorageGroup with of(BoundedContextName) and update its documentation to cover context-scoped grouping.
• Add tests asserting the (group, recordType) identity reaching the StorageFactory.createRecordStorage(..) seam, plus a small StorageGroup factory spec.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
version.gradle.kts	Bumps published snapshot version.
server/src/main/kotlin/io/spine/server/storage/StorageGroup.kt	Adds of(BoundedContextName) for context-based grouping and updates KDoc.
server/src/main/java/io/spine/server/event/store/DefaultEventStore.java	Creates event store record storage under a context-derived StorageGroup.
server/src/test/kotlin/io/spine/server/storage/StorageGroupSpec.kt	Verifies StorageGroup factories for entity class and context name.
server/src/test/kotlin/io/spine/server/event/store/EventStoreIdentitySpec.kt	Asserts event store storage identity is grouped by context and survives SystemAwareStorageFactory wrapping.
server/src/test/kotlin/io/spine/server/entity/storage/HistoryStorageIdentitySpec.kt	Minor punctuation fix in KDoc.
docs/dependencies/pom.xml	Updates generated dependencies POM version.
docs/dependencies/dependencies.md	Updates generated dependency report version/timestamp.
.agents/tasks/event-store-context-prefix.md	Task notes / follow-up plan (not reviewed per repo guidelines).

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[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.82%. Comparing base (2df13c1) to head (5084bf8).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1673      +/-   ##
==========================================
- Coverage   87.87%   87.82%   -0.05%     
==========================================
  Files        1067     1067              
  Lines       22466    22468       +2     
  Branches     1090     1090              
==========================================
- Hits        19741    19733       -8     
- Misses       2346     2354       +8     
- Partials      379      381       +2     

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