Fable Loop

Repeat a check only when repetition can reveal new state, with explicit termination, backoff, error classification, and zero ambiguity about why the loop stopped.

Mission

Polling is not "run the same command until it turns green." A good loop models a changing external condition, distinguishes pending from failure, respects rate/cost budgets, and terminates on success, terminal failure, cancellation, or exhausted budget.

If repeated execution cannot produce new information, the task belongs in diagnosis—not a loop.

Activate When

• waiting for CI/deployment/build/batch-job state to change;
• monitoring a bounded asynchronous operation;
• checking eventually-consistent external state;
• repeating a safe measurement while a known process progresses;
• running a finite stabilization sample where repetition itself is the measurement.