feat: CommandHandler auto-retry on concurrency conflict #156

New issue

Closed

opened 2026-03-01 12:31:09 +00:00 by ash · 0 comments

ash commented

2026-03-01 12:31:09 +00:00

Owner

Problem

When Append returns ErrConcurrencyConflict, the CommandHandler returns the error to the caller. If the caller doesnt retry (common mistake), the command is silently dropped.

Solution

Add configurable auto-retry:

eskit.NewCommandHandler(store, decider,
    eskit.WithConflictRetry(3),              // retry up to 3 times
    eskit.WithConflictRetryDelay(10*time.Millisecond),
)

On conflict: reload events, re-evolve state, re-decide, re-append. Exponential backoff between retries.

This is the standard pattern in event sourcing — the framework should handle it, not every caller.

Priority

High — footgun for every user who forgets to handle ErrConcurrencyConflict

## Problem When Append returns ErrConcurrencyConflict, the CommandHandler returns the error to the caller. If the caller doesnt retry (common mistake), the command is silently dropped. ## Solution Add configurable auto-retry: ```go eskit.NewCommandHandler(store, decider, eskit.WithConflictRetry(3), // retry up to 3 times eskit.WithConflictRetryDelay(10*time.Millisecond), ) ``` On conflict: reload events, re-evolve state, re-decide, re-append. Exponential backoff between retries. This is the standard pattern in event sourcing — the framework should handle it, not every caller. ## Priority High — footgun for every user who forgets to handle ErrConcurrencyConflict