# Kavach Labs

> Replay the crash. Prove the fix. Kavach records every input, clock read and random read a service makes, so a production crash becomes a fixture that replays byte for byte, and a fix only counts when it survives every variation of the incident.

Kavach is open source (Apache 2.0). It records what a service reads (inputs, clock reads, random reads) and writes, so a production crash can be replayed exactly, and checks a fix against variations of the incident before it counts as fixed. Coding agents can drive it.

## Product

- [Home](https://www.thekavachlabs.com/): what Kavach does, how record, replay and verify work
- [Source code](https://github.com/kavachlabs/kavach): the Kavach repository (12 language SDKs, CLI, flight recorder, MCP server)
- [Install script](https://www.thekavachlabs.com/install.sh): `curl -fsSL https://www.thekavachlabs.com/install.sh | sh` (installs `kavach`, `kavach-recorder`, and all 4 Agent Skills on Linux & macOS)
- [Agent skills](https://github.com/kavachlabs/kavach/tree/main/skills): `npx skills add kavachlabs/kavach` (`/kavach-fix`, `/kavach-implement`, `/kavach-setup`, `/kavach-invariants`)
- [Agent guide](https://github.com/kavachlabs/kavach/blob/main/AGENTS.md): `claude mcp add kavach -- kavach mcp` and contract-first workflow
- [Agent benchmark](https://benchmark.kavachlabs.dev): every run of coding agents on the benchmark's incident and feature tasks, with and without Kavach
- [Performance](https://github.com/kavachlabs/kavach/blob/main/BENCHMARKS.md): every measured number, with the command that measured it
- [Release notes](https://www.thekavachlabs.com/release-notes): every release of Kavach, newest first

## Blog

- [What Invariants Should My Service Have?](https://www.thekavachlabs.com/blog/what-invariants-should-my-service-have.md): This post is about state invariants, why developers find it hard to write them, and how we test if an invariant is actually doing its job.
- [How to Read a Kavach Strip Chart](https://www.thekavachlabs.com/blog/how-to-read-a-kavach-strip-chart.md): This post is a reference guide to the strip-chart diagrams on our site, showing how each lane, glyph, step line, and crash marker maps to a Kavach journal.
- [The Hidden Tests Pass. The Contract Doesn't.](https://www.thekavachlabs.com/blog/the-hidden-tests-pass-the-contract-doesnt.md): This post is about why unit tests miss regressions when coding agents build new features, and how contract-first verification catches them before code review.
- [Why Coding Agents Write Narrow Fixes (And Why Logs Won't Save Them)](https://www.thekavachlabs.com/blog/why-coding-agents-write-narrow-fixes.md): This post is about why coding agents write narrow patches that only fix one crash trace, and how replaying 56 variants catches those patches in milliseconds.
- [81.2 Nanoseconds: Designing an Always-On Production Flight Recorder](https://www.thekavachlabs.com/blog/81-nanoseconds-in-process-flight-recorder.md): This post is about where the determinism boundary should live in a backend service, and how our shared-memory ring buffer records every event in 81.2 nanoseconds.
- [Event Sourcing](https://www.thekavachlabs.com/blog/event-sourcing.md): This post is about event sourcing and why the fundamentals of event sourcing matter in this age of agentic software.

## Optional

- [Everything on the blog in one file](https://www.thekavachlabs.com/llms-full.txt)
- [RSS feed](https://www.thekavachlabs.com/blog/feed.xml)
- [Contact](mailto:hello@thekavachlabs.com): hello@thekavachlabs.com