Module engine_journal 

Durable engine journal for restart-safe command/event logging.

This module provides persistent storage for engine commands and their resulting events, enabling:

• Restart-safe ACK: API responses only after DB commit
• Idempotency: duplicate request_id returns cached response
• Auditability: full command + event trace queryable
• Future replay: schema supports snapshot + replay recovery

Structs

EngineJournalWriter

Durable engine journal writer

InMemoryJournalWriter

In-memory journal writer for testing. Exercises real idempotency logic without requiring a database.

JournalAppendResult

Result of appending a transition to the journal

JournalCommandSummary

JournalEventRecord

JournalFullRecord

Enums

EngineJournalError

Error type for engine journal operations

EventPersistenceMode

Event persistence mode for journal writes. Controls the latency/durability tradeoff.

Traits

JournalWriter

Trait for journal writers (enables mock implementations for testing)

Functions

ensure_no_fill_events 🔒

get_critical_event_types 🔒

Get the set of critical event types that are always persisted in Full mode. These events are needed for the outbox publisher to replay state correctly. Configured via ENGINE_JOURNAL_CRITICAL_EVENT_TYPES env var. Default: “L2Update” (essential for cache state rebuild)

is_critical_event_type 🔒

Check if an event type is critical and should always be persisted in Full mode

Type Aliases

SharedEngineJournalWriter

Thread-safe wrapper for journal writers (trait object for mock support)