Reliability Primitives (Retry / Fallback / Circuit Breaker)

The Problem It Solves

Real systems fail:

• transient errors (timeouts, rate limits)
• flaky tools
• upstream outages

Reliability primitives are cross-cutting “safety rails”.

Primitives

• Retry: try again with backoff.
• Fallback chain: try alternative strategies/providers.
• Circuit breaker: stop calling a failing dependency for a while.

flowchart TD
  C["Call dependency"] --> E{"Error?"}
  E -->|no| OK["Return"]
  E -->|yes| R["Retry/backoff"]
  R --> CB{"Too many failures?"}
  CB -->|yes| OPEN["Circuit open"]
  CB -->|no| C

Repo Reference

• Implementation: src/agent_patterns_lab/runtime/reliability.py
• Tests: tests/test_reliability.py