Module observability 

Phantom Protocol observability subsystem.

Replaces the Phase 4.5 hand-rolled metrics module (transport::metrics). Lock-free hot-path atomics for per-packet recording plus opt-in OpenTelemetry instruments (metrics + traces) gated behind the telemetry-otel Cargo feature.

See docs/observability/refactor-plan.md for the full design and docs/observability/metrics-catalog.md for the instrument inventory. This file is the public module surface; concrete types live in the submodules below.

Layout

• atomics — lock-free hot-path counters (HotPathAtomics).
• config — ObservabilityConfig (namespace, histogram buckets).
• instruments — OTel instrument holder; ZST no-op when the feature is off.
• bridge — registers ObservableCounter callbacks over the atomics.
• attrs — typed attribute-value enums (the cardinality contract).
• snapshot — MetricsSnapshot, a cold-path read for FFI / debug.

Re-exports

pub use attrs::leg_str;

pub use attrs::AeadAlgorithm;

pub use attrs::CookieOutcome;

pub use attrs::Direction;

pub use attrs::EarlyDataOutcome;

pub use attrs::FallbackReason;

pub use attrs::HandshakeOutcome;

pub use attrs::PathValidationOutcome;

pub use attrs::PowOutcome;

pub use attrs::ProtocolVersion;

pub use attrs::ReplayReason;

pub use attrs::ResumptionMode;

pub use config::HistogramConfig;

pub use config::ObservabilityConfig;

pub use config::ObservabilityConfigBuilder;

pub use snapshot::MetricsSnapshot;

Modules

attrs

Typed attribute values for OpenTelemetry instruments.

config

Observability configuration.

snapshot

Cold-path snapshot of the observability state.

Structs

Observability

Public observability facade.