Golden signals expose overload

Service26 monitoring needs all four golden signals. Separate symptom detection from internal diagnosis, and distinguish failed-request latency from successful latency.

The four golden signals of monitoring are latency, traffic, errors, and saturation.

Source: Q1833; B833.

Failure it prevents

A service reports fast responses while errors rise or scarce capacity is exhausted.

Our Effect 4.0.0 reading

Metric.counter, gauge, and histogram supply instruments. Connect backlog and parked-work observations through the actual adapters. Define alerts and response outside these constructors.

Source: packages/effect/src/Metric.ts.

How to check

Create a slow dependency and a parked item. Verify that user-visible failure and resource saturation are observable. This check is our proposal. The books do not prescribe it.

Continue with Dead letters need a return path14, Admission control protects recovery10.

Connect this to the existing rat-stack guidance23.

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

Sources

  1. Ewaschuk, Rob. Monitoring Distributed Systems. O’Reilly, 2016.. O’Reilly. The Four Golden Signals; Black-Box Versus White-Box; Symptoms Versus Causes. Accessed 2026-10-23.
  2. Effect contributors. Effect 4.0.0. Metric.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.

    Golden signals expose overload — Measure latency, traffic, errors, and saturation, including failed work.

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

    Golden signals expose overload — new page: docs(lore): land the durability wiki pages and bibliography

  3. Dead letters need a return path. Exhausted work needs durable evidence, an owner, and deliberate redrive.

    Continue with Retry needs idempotent effects, Golden signals expose overload.¶

  4. durability. Keep a rat-stack app standing when a provider, pool, or dependency slows down or a worker dies. Use at any I/O boundary, connection pool, provider call, shared waiter, fan-out, flag, gate, or work that can outlive a request, or when asked "what happens when this is slow", "add a timeout", "make this durable", or "what survives a crash".

    The Four Golden Signals.

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

    The Four Golden Signals¶

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

    Golden signals expose overload: Measure latency, traffic, errors, and saturation, including failed work.¶

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

    Golden signals expose overload — Measure latency, traffic, errors, and saturation, including failed work.

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

    Golden signals expose overload — new page: docs(lore): land the durability wiki pages and bibliography