CodeSampleX MCP server

CodeSampleX

Tested. Not guessed.

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CodeSampleX is an open compatibility testing network for developer libraries, runtimes and toolchains. It does not summarize documentation and it does not collect anecdotes. It records what real builds actually did, in environments recorded rather than assumed — then shows you where things worked, where they broke, and in which environment.

Two things are the asset, and a third is a bonus:

• Evidence — real builds on real developer machines, with the environment, stage, structured termination, and secret-safe normalized failure fingerprint. Missing or legacy failure detail is shown as an Evidence gap, never invented as a cause. It arrives automatically wherever csx is installed, so it reaches platforms no container lane can: no container reproduces a macOS host — Docker on a Mac runs a Linux VM, which is a different machine wearing the same laptop — npm publishes no Windows image, and the long tail of musl, ARM, corporate base images and actually-installed runtime versions is unbounded. This is the only thing that can fill the map.
• Findings — the contradictions we detected in that evidence: what a competent developer or model expects, measured against what happened. These are ours to stand behind, and they are what a model most often gets wrong, because they are exactly what the documentation does not say.
• Samples — runnable code we write and verify ourselves. A bonus, deliberately: a container farm can never cover the space, so a verified sample is a confidence tier above the evidence, never the condition for having an answer at all.

Which is why a miss is not empty. When nothing has been proven for your case the grade stays NOSAFEMATCH — and the recorded observations come back with it, as recorded.

• Compatibility map: https://codesamplex.dev
• The question it answers: does it run there? — this API, on this version, on this OS, under this runtime.
• The answer it gives: here is what happened, and here is where it ran. Reporters use rotating peer buckets; separate first-party activity analytics use a stable pseudonymous client ID, never a name or IP identity. See analytics semantics.

What ships today

CodeSampleX is no longer just a search command. The shipped product now exposes several surfaces, all backed by the same evidence model:

Shortened. The full README is on GitHub.