Orbit v0: Building Blocks (Phase 1)

Small, sharp components you will later embed in Orbit. Build from scratch, no frameworks.

orbit-kv (Java): thread-safe KV with TTL + LRU, RESP-like TCP protocol on virtual threads → later becomes the idea behind the gateway’s cache
orbit-ratelimit (Java + Go): token bucket, sliding-window log, and sliding-window counter; identical test vectors in both languages
orbit-dag (Go): in-memory DAG executor: JSON workflow → topo sort (Kahn) → bounded-parallel execution, per-step timeout, retries with exponential backoff + jitter, cancel-on-failure with context → the seed of orbit-engine
orbit-expr (Go): tiny expression language (lexer + Pratt parser + evaluator) for step conditions like steps.a.output.score > 0.8 && input.tier == "pro" (Writing an Interpreter in Go ch. 1–3)
Mini Redis (Go): CodeCrafters/codingchallenges stages
LLD rounds modeled on Orbit: design the class model for Workflow, Step, Run, StepExecutor (Strategy), RetryPolicy, StepState (State pattern)

Definition of done

All race-detector / concurrency tests green · [ ] Benchmarks (JMH, go test -bench) committed · [ ] README per module · [ ] ADR-000: “Why Java for the control plane and Go for the data plane”