evolveguard

What it does • Quickstart • CLI reference • Agent-native usage • MCP server • How it compares • FAQ

Catch behavioral drift when a Claude Agent Skill or a Claude Code MEMORY.md file edits itself, before the edit ships.

# PyPI -- Python CLI + library (genuine port, not a Node wrapper)
pip install evolveguard-cli

# npm -- JavaScript/TypeScript CLI + library
npm install -g evolveguard-cli

[!NOTE] Both packages are live and named consistently: evolveguard-cli on PyPI and evolveguard-cli on npm (renamed 2026-07-19 from the old plain evolveguard, which is now deprecated on both registries). npm install -g evolveguard-cli and pip install evolveguard-cli both work today; the demo GIFs below were recorded against the published packages, not a local build.

What it does

evolveguard record ./SKILL.md --fixtures ./fixtures.json
# ... skill gets edited, by a human or an agent ...
evolveguard check ./SKILL.md

EvolveGuard v0.1.4 -- Regression Check
skill: monorepo-scanner  baseline: 2026-07-15  fixtures: 1

[DRIFT] fixture: "scan a monorepo"  new tool call: fs.write (baseline had none)
         -> new tool call: fs.write (baseline had none) -- this edit introduces a
            capability the baseline never used

0 PASS, 1 DRIFT, 0 FAIL
exit code 1 (DRIFT blocks merge by default; override with --allow-drift)

That's real output from this repo's own fixtures/labeled-non-breaking-edits/case-03-add-write-capability/ test case, wired to filesystem: read-only becoming read-write in the skill's frontmatter. Reproduce it yourself: evolveguard record the before/SKILL.md in that folder against its fixtures.json, then evolveguard check the after/SKILL.md.

Features

Static analysis, not a live agent run. record parses a skill file's YAML frontmatter (declared tools, network, filesystem, scope, and any bundled hooks), scans the skill's body text and hook scripts for evidence of network calls or filesystem writes, and combines both into a capability surface. check re-parses the edited file with the same logic and diffs the result. Neither command runs eval, shells out to a subprocess, or executes a skill's hook scripts, in either the TypeScript or the Python distribution.

Two-level diffing catches drift a single fixture can miss. Each fixture's expectedToolCalls filters the recorded capability surface down to what that fixture cares about, but check also diffs the skill's whole capability surface separately. A new capability that no fixture's expectedToolCalls happens to cover still shows

... View full README on GitHub