[claude] Claude adding fetch latest

[p14n]

Summary by Sourcery

Add support for fetching and processing the single latest message in CatchupService, wired through a new SystemEvent.FetchLatest, backed by server- and gRPC-side getLatestMessageId, with accompanying tests and build publishing setup

New Features:

• Implement fetchLatest in CatchupService to process the newest event beyond the current high-water mark and persist it
• Introduce SystemEvent.FetchLatest and SystemEventBroker.triggerFetchLatest to initiate fetch-latest workflows
• Extend CatchupServerInterface, CatchupServer, CatchupGrpcClient, and CatchupGrpcServer with getLatestMessageId to retrieve the highest message ID for a topic

Build:

• Add gradle.properties with Maven Central credentials and signing configuration for artifact publishing

Tests:

• Add CatchupServiceTest methods to verify fetchLatest behavior with and without new messages

[sourcery-ai]

Reviewer's Guide

This PR introduces a fetchLatest feature that compares the current high‐water mark against the latest server message ID, fetches and persists one new event if available, extends the catchup server and gRPC layers to expose latest‐ID lookup, adds a system event path to trigger fetchLatest, and includes unit tests covering both new‐message and no‐newer‐message scenarios.

Sequence diagram for fetchLatest event processing

sequenceDiagram
    participant SystemEventBroker
    participant CatchupService
    participant CatchupServer
    participant Database

    SystemEventBroker->>CatchupService: Publish SystemEvent.FetchLatest
    CatchupService->>CatchupServer: getLatestMessageId(topic)
    CatchupServer->>Database: SELECT MAX(idn) FROM postevent.{topic}
    Database-->>CatchupServer: latestId
    CatchupServer-->>CatchupService: latestId
    CatchupService->>CatchupServer: fetchEvents(latestId-1, latestId, 1, topic)
    CatchupServer-->>CatchupService: List<Event>
    CatchupService->>Database: writeEventsToMessagesTable(events)
    CatchupService->>SystemEventBroker: Publish SystemEvent.CatchupRequired (if event processed)
    CatchupService-->>SystemEventBroker: Return processedCount

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Class diagram for CatchupServerInterface and implementations with fetchLatest support

classDiagram
    class CatchupServerInterface {
        +List<Event> fetchEvents(long, long, int, String)
        +long getLatestMessageId(String)
    }
    class CatchupServer {
        +List<Event> fetchEvents(...)
        +long getLatestMessageId(String)
    }
    class CatchupGrpcClient {
        +List<Event> fetchEvents(...)
        +long getLatestMessageId(String)
    }
    class CatchupGrpcServer {
        +void getLatestMessageId(GetLatestMessageIdRequest, StreamObserver)
    }
    CatchupServerInterface <|.. CatchupServer
    CatchupServerInterface <|.. CatchupGrpcClient
    CatchupGrpcServer --> CatchupServer : uses

    class CatchupService {
        +int fetchLatest(String)
        +void onMessage(SystemEvent)
    }
    class SystemEventBroker {
        +void triggerFetchLatest(String)
    }
    class SystemEvent {
        CatchupRequired
        UnprocessedCheckRequired
        FetchLatest
        String topic
    }

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Class diagram for SystemEvent and SystemEventBroker changes

classDiagram
    class SystemEvent {
        <<enum>>
        CatchupRequired
        UnprocessedCheckRequired
        FetchLatest
        String topic
    }
    class SystemEventBroker {
        +void triggerFetchLatest(String)
    }

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File-Level Changes

Change	Details	Files
Introduce fetchLatest method in CatchupService	Retrieve current HWM from the database Invoke catchupServer.getLatestMessageId to get the latest ID Fetch and write the single new event when ID > HWM, commit, and publish CatchupRequired Extend onMessage to handle SystemEvent.FetchLatest	CatchupService.java
Extend CatchupServer and gRPC layers to support latest‐ID retrieval	Add getLatestMessageId to CatchupServerInterface Implement MAX(idn) query in CatchupServer Expose getLatestMessageId RPC in CatchupGrpcServer Invoke gRPC stub in CatchupGrpcClient.getLatestMessageId	CatchupServerInterface.java CatchupServer.java CatchupGrpcServer.java CatchupGrpcClient.java
Add system‐event trigger for fetchLatest	Add FetchLatest enum value in SystemEvent Add triggerFetchLatest helper in SystemEventBroker	SystemEvent.java SystemEventBroker.java
Add unit tests for fetchLatest behavior	Test branch with a newer message (processes one event) Test branch with no newer message (processes zero) Add getMaxIdnFromMessagesTable helper to verify DB state	CatchupServiceTest.java
Update build properties with publishing credentials	Add Maven Central username/password Configure signing key ID and password	gradle.properties

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