Spoor

Spoor is a family of Rust crates for low-overhead instrumentation, semantic tracing, counters, memory observation, and downstream projection into existing profiling and visualization tools.

The workspace currently contains:

• spoor_core: foundational ids, descriptors, context, levels, and emission primitives
• spoor: a thin facade over spoor_core
• spoor_runtime: bounded in-process collection and snapshot extraction
• spoor_memory: scratch and cache helpers layered over core counters
• spoor_session: transport-neutral snapshot envelopes for downstream consumers
• spoor_session_wtransport: local attach path for discovery and snapshot fetch over WebTransport
• spoor_fanout: backend composition for feeding multiple sinks at once
• spoor_tracing: a tracing subscriber layer that forwards spans and events into Spoor
• spoor_benchmarks: top-level benchmark wind tunnel for substrate overhead
• examples/basic: a top-level example crate to avoid spreading dev dependencies through core packages

External Use

Spoor is intended to be usable from outside this repo in two directions:

• instrument your own application with spoor, spoor_runtime, and related helper crates
• build a separate consumer or UI that attaches to a running Spoor session

Start here:

• Instrumenting an App
• Session Consumer Contract
• WebTransport Session Wire Format
• Migration Notes

Local Attach

The current local attach workflow is:

1. your process installs spoor_runtime
2. your process serves sessions through spoor_session_wtransport
3. a consumer connects to the fixed local server and discovers active sessions

The examples show that flow directly:

• cargo run -p basic --bin session_wtransport for a one-process serve/discover/fetch round trip
• cargo run -p basic --bin session_server
• cargo run -p basic --bin session_consumer

The session examples include direct Spoor instrumentation plus tracing spans/events bridged through spoor_tracing. For a compact Chrome Trace JSON view of just the tracing bridge:

• cargo run -p basic --bin tracing_demo > /tmp/spoor-tracing.json