witness
by Community
A flight recorder for AI agent fleets that pays for itself — provenance-native caching proxy for model APIs (Pact + AgentReplay)
OSS
witness
Added 1 Oct 2026
Overview
Witness is a Rust-based observability tool for AI agent fleets. It operates as a caching proxy for model APIs, recording agent activity for replay while tracking data provenance. The proxy reduces model API costs by serving cached responses where appropriate.
Best for
Best for
Teams running AI agent fleets that want to cut API costs while retaining replayable audit trails
Use cases
- Trace agent decision paths across a fleet
- Replay past agent sessions for debugging
- Reduce model API spend with response caching
Notes
0 stars on GitHub. Last updated 2026-09-11. Licensed MIT.
Pros
- Provenance-aware caching directly cuts API costs
- Flight recorder style logging captures full agent state
- Rust provides low overhead for high-throughput proxy workloads
Cons
- Zero GitHub stars suggests a very early-stage project
- Community-only support may mean limited maintenance guarantees
- Focus on model API calls may not cover broader observability needs
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