Borrowing it
Nothing to install: this file belongs to webern/mx. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/webern/mx/main/.github/instructions/corpus-and-tests.instructions.mdgit clone --depth 1 https://github.com/webern/mxWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/webern/mx/corpus-and-tests)<a href="https://agentmods.dev/instructions/webern/mx/corpus-and-tests"><img src="https://agentmods.dev/badge/instructions/webern/mx/corpus-and-tests/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/webern/mx/corpus-and-tests"><img src="https://agentmods.dev/badge/instructions/webern/mx/corpus-and-tests.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00282 | $0.00282 |
| Opus 5.5 | $0.00113 | $0.00113 |
| Sonnet 5.5 | $0.00056 | $0.00056 |
| Haiku 4.5 | $0.00028 | $0.00028 |
Grade A, and why
mx corpus-and-tests.instructions.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
data/ is the MusicXML test corpus; src/private/mxtest/ holds the test suites
(see data/README.md). Review for:
- Adding or removing a corpus file requires: the pinned count bump in
src/private/mxtest/corert/CoreRoundtripTest.cpp, regenerated audit artifacts (make audit: the*.features.xmlsidecar anddata/corpus.xml), and a greenmake core-roundtrip-test. Flag a corpus change missing any of these. - A deliberately unparseable file needs a sibling
<name>.invalidmarker explaining why; a schema-invalid-but-lenient file needs a<name>.fixup.xmlsidecar. New fixups must follow the uniform leniency policy indata/README.md, not invent per-file rules. roundtrip-baseline.txt(the api round-trip pass list) only grows by deliberate commits; flag removals or unexplained churn.ApiLoadSmokeTestonly proves a file imports without crashing; a feature claim needs a fixture pinned in the read->write->read gate (make api-roundtrip).- Test code follows the same C++ rules as the library (no new anonymous namespaces).
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 20 lines · 282 tokens per session scan A 74239602a87f
mx corpus-and-tests.instructions.md is an instructions file published in the GitHub repository webern/mx (93 stars, last pushed yesterday), licensed MIT. It adds 282 tokens to every session, about $0.0011 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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