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supercorp-ai

supercov

Code quality and coverage for coding agents: a Rust CLI that scores files with Jev, runs your existing test command, and turns uncovered paths into small actionable targets.

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Curator's take

Point your agent at it when the instruction 'write some tests' keeps producing tests that prove nothing: supercov runs the suite the repo already trusts, reports lines/branches/MC-DC, and lists the specific uncovered obligations so the agent has a target it can verify it hit. The quality half asks Jev yes/no questions per file (long_method, deep_nesting ...) and does the arithmetic locally, so every score decomposes into claims you can check against the source - about a cent per megabyte, cached by content. Coverage needs no account, key or reporter; quality needs a hosted TypeSafe key. Eight languages. Don't expect a verdict on correctness: coverage and the assertion map tell you what ran and what was asserted, not whether the behaviour is right, and the assertion score is agent-assessed by design.

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README.md2 min read

Code quality and coverage for coding agents

Code quality and coverage for coding agents

Supercov tells your coding agent what to fix and what to test. It scores your code quality with Jev, runs the test command you already use, and turns uncovered paths into small, actionable queries. Your agent picks a target, writes a focused test or a focused refactor, proves what improved, and keeps going.

Paste this to your coding agent to start:

Measure code quality with npx supercov.

Scoring needs a TypeSafe AI API key, and your coding agent will usually ask you for it. It costs about a cent per megabyte of source. Coverage needs no account, config file, import, custom reporter, or hosted service. Supercov is local, free, open source, and MIT licensed.

Website · Documentation · npm · GitHub

Supported languages: JavaScript · TypeScript · Rust · Python · Ruby · Go · Java · Kotlin.

Supported by Supercorp.

Agent workflow: ask your coding agent to add a test in your own project, with a recorded example to follow along.

Score your code

export TYPESAFE_API_KEY=...   # get one at https://typesafe.ai
npx supercov quality

No arguments and no configuration. It finds your source, asks Jev a set of yes/no questions about each file, and does the arithmetic itself, so every part of a score is a claim you can check against the file.

Quality weak (3.8/10) over 163 files.
  11 good, 52 fair, 100 weak.

Weakest:
  weak  runtime/python/supercov_runtime.py
        long_method 0.96, deep_nesting 0.92, complex_conditional 0.89, +9 more
  weak  crates/supercov-engine/src/assertion_store.rs
        long_method 0.96, deep_nesting 0.91, complex_conditional 0.86, +8 more

Narrow to what fired, read one file in full, or review a change:

npx supercov quality gaps
npx supercov quality file src/server.ts
npx supercov quality patch                    # your uncommitted work, or your branch
npx supercov quality patch --annotate github  # workflow annotations, no token

Jev charges for what it reads and nothing for what it writes, so a megabyte of source costs a little over a cent. Answers are cached by content, so a second run pays only for what changed. See Understanding quality.

Start with the suite you already have

npx supercov -- npm test

Other ways in, all the same binary at the same version: brew install supercorp-ai/tap/supercov, or for a Go project go run github.com/supercorp-ai/supercov/cmd/supercov@latest.

Everything after -- is your test command. Supercov runs it without changing your source, tests, runner configuration, or normal build output.

Then read the result and ask what is still uncovered:

npx supercov runs latest

run run_7fc676ba671d42be
command: npm test

Coverage
  Lines      100.00% (5/5)
  Branches   66.67% (4/6)
  MC/DC      33.33% (1/3)

npx supercov runs latest gaps --limit 10

Coverage gaps — only files with unresolved obligations

src/pricing.js
  uncovered: lines 0  statements 1  functions 0  branch outcomes 0  MC/DC conditions 2

After your agent adds a test, rerun the complete suite and prove the gain:

npx supercov -- npm test
npx supercov diff <previous-run-id> latest

Use whichever complete test command the repository already trusts:

npx superco