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Long-form notes on software, distributed systems, and the craft of building. Shipping one a week.
Catching a Retry Race with One Seed: Deterministic Simulation in Rust using turmoil
I had three flaky retry tests no one could reproduce on a laptop. I rewrote one in Rust on top of turmoil, Tokio's deterministic simulator, and a single 8-byte seed pinned the partition race byte-for-byte. These are my notes on what the seed actually controls, what leaks past it, and when deterministic simulation testing is worth the seam.
Durable Execution Isn't About Agents — It's About Replayable Backend Workflows
I came to durable-execution runtimes through the agent press, but the constraint that surprises everyone is determinism on replay. These are my notes from working a six-step payment reconciliation as a Restate workflow in TypeScript — the line that broke replay, the mental model that fixed it, and the trade-offs that come with the pattern.