Circuit breakers have state

A circuit breaker is a stateful guard around a dependency. It differs from retry. Its state determines whether a dependency call is attempted. Threshold accounting must match the actual implementation.Ā¶

calls to the circuit breaker fail immediately, without any attempt to execute the real operation.Ā¶

Source: Q0633; B433, B1133.Ā¶

Failure it prevents

Callers keep spending capacity on a known-unhealthy dependency.Ā¶

Our Effect 4.0.0 reading

No dependency circuit-breaker API was found. Compose timeout20 and typed failure handling with an explicit XState lifecycle. Define whether state is local or shared.Ā¶

Source: packages/effect/src/Effect.ts, packages/effect/src/Schema.ts.Ā¶

How to check

Generate success, failure, timeout, cooldown, and probe histories. Verify exact threshold semantics and visible state changes. This check is our proposal. The books do not prescribe it.Ā¶

Continue with Bulkheads isolate scarce capacity10, Supervision chooses what restarts11.Ā¶

Connect this to the existing rat-stack guidance26.Ā¶

Use the durability skill for the full review. Return to the durability index34.Ā¶

Sources

  1. Nygard, Michael T. Release It!: Design and Deploy Production-Ready Software. Pragmatic Bookshelf, 2007.. Pragmatic Bookshelf. Ā§4.4 Unbounded Result Sets; Chapter 5 Stability Patterns: Ā§5.1 Timeouts, Ā§5.2 Circuit Breaker, Ā§5.3 Bulkheads, Ā§5.4 Steady State, Ā§5.5 Fail Fast, Ā§5.6 Handshaking, Ā§5.7 Test Harness, Ā§5.8 Decoupling Middleware. Accessed 2026-10-23.
  2. Hebert, Fred. Property-Based Testing with PropEr, Erlang, and Elixir. Pragmatic Bookshelf, 2019.. Pragmatic Bookshelf. Chapter 7 Shrinking; Laying Out Stateful Properties; Testing Parallel Executions; Initial State for the State Machine; Adjusting the Model. Use the actual breakerā€™s threshold semantics. Accessed 2026-10-23.
  3. Effect contributors. Effect 4.0.0. Effect.ts. Effect-TS. Pinned source for our Effect mapping, not a claim from the book. Accessed 2026-10-23.
  4. Effect contributors. Effect 4.0.0. Schema.ts. Effect-TS. Pinned source for our Effect mapping, not a claim from the book. Accessed 2026-10-23.

Last changed 2026-10-23 in 58dc623. Source on GitHub. Change log.

Linked from

  1. Agent guide. An Effect stack so pure (aspirational) Kit Langton will blush.

    Circuit breakers have state ā€” A breaker stops doomed calls and controls probes before restoring traffic.

  2. Change log. What changed in the files served here, newest first.

    Circuit breakers have state ā€” new page: docs(lore): land the durability wiki pages and bibliography

  3. Durability bibliography. Books, checked short quotations, source limits, and Effect mapping provenance.

    2 Circuit BreakerĀ¶

  4. Durability starts with a recovery record. A reading order for storage, replay, worker ownership, overload, and recovery tests.

    Circuit breakers have state: A breaker stops doomed calls and controls probes before restoring traffic.Ā¶

  5. Full agent guide. An Effect stack so pure (aspirational) Kit Langton will blush.
  6. Rat Stack lore | rat-stack. Short, source-grounded notes on the ideas and decisions behind rat-stack.

    Circuit breakers have state ā€” A breaker stops doomed calls and controls probes before restoring traffic.

  7. Recovery needs model tests. Test sequences of failures and recoveries against explicit invariants.

    Continue with Checkpoints follow the promised commit, Circuit breakers have state.Ā¶

  8. Retry load needs a budget. One retry owner must control attempts, delay, and aggregate load.

    Continue with Circuit breakers have state, Admission control protects recovery.Ā¶

  9. Source change history (log.md). The generated change log as Markdown.

    Circuit breakers have state ā€” new page: docs(lore): land the durability wiki pages and bibliography

  10. Supervision chooses what restarts. Restart policy follows dependency shape and bounds repeated recovery.

    Continue with Restart must reconstruct known state, Circuit breakers have state.Ā¶