Composable middleware chain for job execution.

Middleware wraps job execution with before/after logic. Each middleware is a function that receives the job map and a Next function. Call Next() to continue the chain, or return early to short-circuit.

Writing Middleware

my_middleware(Job, Next) ->
    %% Before
    logger:info(\"starting job\", #{job_id => maps:get(id, Job)}),
    Result = Next(),
    %% After
    logger:info(\"finished job\", #{job_id => maps:get(id, Job)}),
    Result.

Middleware Order

Built-in middleware runs in this order:

1. Logger metadata (sets structured log context)
2. Seki resilience (rate limit, bulkhead, circuit breaker)
3. Global middleware (from config)
4. Worker middleware (from worker callback)
5. Worker:perform/1