Build: A Practical Multi-Agent Reliability Playbook from GitHub's Deep Dive

If your multi-agent workflow keeps failing in unpredictable ways, implement four controls first: typed handoffs, explicit state contracts, task-level evals, and transactional rollback. GitHub's engineering deep dive published on February 24, 2026 shows the same core pattern: most failures are orchestration failures, not model-IQ failures, so reliability comes from workflow design before model tuning. The Problem GitHub's deep dive highlights where multi-agent systems break when moving from a single coding assistant to multiple specialized agents. The repeated pain points are practical: Handoffs are ambiguous, so downstream agents infer missing context. Shared state mutates without schema discipline, causing drift and duplication. Success checks happen too late (end-of-run), so bad branches accumulate cost. Failed steps are hard to isolate, so recovery is "start over" instead of rollback. That failure profile is expensive. One weak handoff can trigger a cascade of retries across planner