feat(indexing): support definition storage

[yordis]

• Keep index lifecycle state behind a focused core boundary before transport wiring is introduced.
• Preserve idempotent create and list semantics where later lifecycle code can depend on them.

[cursor]

PR Summary

Low Risk
New isolated core types and in-memory store with no production wiring or persistence yet; behavior is fully covered by unit tests.

Overview
Introduces a core storage boundary for index definitions before any transport wiring: IIndexDefinitionStore with create, read, list, and delete, plus an in-memory implementation.

Create is idempotent when the same or equivalent IndexDefinition is submitted (AlreadyExists); a different definition under the same name returns Conflicts without overwriting. List returns definitions sorted by name; tests assert snapshot semantics on the returned collection.

Adds IndexName (lowercase alphanumeric, _, -) and StoredIndexDefinition. IndexDefinition gains value equality and GetHashCode so duplicate creates can be detected reliably.

Coverage includes store behavior, name validation, and definition equality tests.

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 7634a374-0cff-471d-928b-6cddd85cfe78

📥 Commits

Reviewing files that changed from the base of the PR and between f662b88 and fadc1be.

📒 Files selected for processing (5)

• src/EventStore.Core.XUnit.Tests/Services/Storage/Indexing/InMemoryIndexDefinitionStoreTests.cs
• src/EventStore.Core.XUnit.Tests/Services/Storage/Indexing/IndexDefinitionTests.cs
• src/EventStore.Core/Services/Storage/Indexing/IIndexDefinitionStore.cs
• src/EventStore.Core/Services/Storage/Indexing/InMemoryIndexDefinitionStore.cs
• src/EventStore.Core/Services/Storage/Indexing/IndexDefinition.cs

Walkthrough

Adds IndexName (a validated value object), IIndexDefinitionStore interface with IndexDefinitionCreateResult enum and StoredIndexDefinition record, InMemoryIndexDefinitionStore (lock-guarded dictionary implementation), and full xUnit test coverage for both IndexName and the store.

Changes

Index Definition Store

Layer / File(s)	Summary
IndexName and store contracts src/EventStore.Core/Services/Storage/Indexing/IndexName.cs, src/EventStore.Core/Services/Storage/Indexing/IIndexDefinitionStore.cs	IndexName sealed record validates input (lowercase alphanumeric, underscore, dash only). IIndexDefinitionStore defines async Create, Read, List, Delete; IndexDefinitionCreateResult enum covers Created/AlreadyExists/Conflicts; StoredIndexDefinition record wraps name and definition with null guards.
InMemoryIndexDefinitionStore src/EventStore.Core/Services/Storage/Indexing/InMemoryIndexDefinitionStore.cs	Lock-guarded dictionary keyed by IndexName.Value implements all four store operations with null-argument and cancellation checks.
Tests src/EventStore.Core.XUnit.Tests/Services/Storage/Indexing/IndexNameTests.cs, src/EventStore.Core.XUnit.Tests/Services/Storage/Indexing/InMemoryIndexDefinitionStoreTests.cs	IndexNameTests covers valid/invalid construction and ToString. InMemoryIndexDefinitionStoreTests covers CRUD semantics, idempotency, conflict detection, snapshot behavior, argument validation, and cancellation.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 A name must be tidy, no spaces allowed,
Just dashes and letters—the rabbit is proud.
The store holds your indexes, safe under lock,
Create, read, or delete, tick-tock, tick-tock.
Tests confirm every path, even cancel with grace—
A hoppy new feature lands right into place! 🌿

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding index definition storage support.
Description check	✅ Passed	The description matches the change by mentioning index lifecycle state and idempotent create/list semantics.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch yordis/feat-index-definition-store

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[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/EventStore.Core/Services/Storage/Indexing/IIndexDefinitionStore.cs`:
- Line 12: The IIndexDefinitionStore.Read contract currently claims a non-null
StoredIndexDefinition even though the implemented behavior is null when the
index is missing. Update the Read signature in IIndexDefinitionStore to return a
nullable StoredIndexDefinition, and make sure any implementations and callers of
Read are aligned with that nullable contract so missing definitions are handled
safely instead of being treated as always present.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 4275a07b-7891-4f0c-923f-5c2e1c2f1a69

📥 Commits

Reviewing files that changed from the base of the PR and between f44b7f5 and f662b88.

📒 Files selected for processing (5)

• src/EventStore.Core.XUnit.Tests/Services/Storage/Indexing/InMemoryIndexDefinitionStoreTests.cs
• src/EventStore.Core.XUnit.Tests/Services/Storage/Indexing/IndexNameTests.cs
• src/EventStore.Core/Services/Storage/Indexing/IIndexDefinitionStore.cs
• src/EventStore.Core/Services/Storage/Indexing/InMemoryIndexDefinitionStore.cs
• src/EventStore.Core/Services/Storage/Indexing/IndexName.cs