failed-experiments

A rule for preserving source files that are failed verification experiments. Verus is a tool that checks formal claims about Rust code; a failed experiment records something it could not prove.

In plain words
What is it for?
Use it when an experiment does not verify: document the failure, leave its code unchanged, and exclude it from the main module list.
Why use it?
It keeps unsuccessful attempts available as evidence and prevents changing them just to hide the failure.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/briangmilnes/apas-verus/failed-experiments
Clone the repo
git clone --depth 1 https://github.com/briangmilnes/APAS-VERUS

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 196 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00196
Opus 5 $0.00000 $0.00098
Sonnet 5 $0.00000 $0.00039
Haiku 4.5 $0.00000 $0.00020

Measured 3d ago against content hash 5ee397dc1c5f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

failed-experiments 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 3d 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.

.cursor/rules/apas-verus/failed-experiments.mdc · 32 lines

What it actually says

Failed Experiments

When an experiment file fails verification:

  • DO NOT modify it to pass (no adding assume, no commenting out failing assertions)
  • DO NOT remove dead code — failed attempts stay as documentation
  • DO add a RESULT: FAILS comment at the top explaining what fails
  • DO comment out the module in lib.rs so the project validates

Failed experiments are valuable documentation of what Verus cannot (yet) do.

Example

//! Proof time test: Does X work?
//! RESULT: FAILS - assertion on line 30 cannot be proven

// ... original failing code unchanged ...

In lib.rs:

//    pub mod experiment_that_fails;  // FAILS - see file header
Changes

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.

  1. 3d ago First seen · 32 lines · 0 tokens per session scan A 5ee397dc1c5f

Subscribe to this mod's changes

failed-experiments is a cursor rule published in the GitHub repository briangmilnes/APAS-VERUS (10 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 196 tokens. 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 2026-08-31.