03: Control Flow and Stateful Lifecycles

Goal: model long-running and branching operations without losing clarity.

Recommended examples

grapheme run examples/resilience-composition.gr --json
grapheme run examples/realworld/feature-flag-progressive-rollout.gr --json
grapheme run examples/realworld/oncall-escalation-ladder.gr --json

Patterns

• loop with bounded max
• gate conditions for promotion/rollback
• explicit terminal states

Exercise

For feature flag rollout:

1. lower canary score below threshold,
2. rerun,
3. compare done vs rolled_back paths.

This teaches safe progression and failure semantics.