Module checkpoint 

Checkpoint state types and I/O for the compaction engine.

The checkpoint is the materialized state produced by reducing all events. It lives at checkpoint/state.json in the hub cache and tracks display ID allocation, lock state, issue state, and compaction metadata.

Structs

CheckpointState

Materialized state produced by compaction.

CompactIssue

Compact issue representation for reduction (tracks mutable fields only).

CompactionLease

Advisory compaction lease to prevent concurrent compaction.

LockEntry

A lock entry in the checkpoint state.

SkewWarning

Warning about clock skew detected during compaction.

UnsignedEventWarning

Warning about an unsigned event encountered during compaction.

Functions

read_checkpoint

Read checkpoint state from disk. Returns default if missing.

read_watermark

Read the compaction watermark (last processed ordering key).

write_checkpoint

Write checkpoint state to disk (pretty-printed JSON).

write_watermark

Write the compaction watermark.