Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add cameronfreer/lean4-skills/plugin install lean4Wrote 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/commands/cameronfreer/lean4-skills/disprove)<a href="https://agentmods.dev/commands/cameronfreer/lean4-skills/disprove"><img src="https://agentmods.dev/badge/commands/cameronfreer/lean4-skills/disprove.svg" alt="Measured on agentmods" 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 | $0.00012 | $0.04418 |
| Opus 5 | $0.00006 | $0.02209 |
| Sonnet 5 | $0.00002 | $0.00884 |
| Haiku 4.5 | $0.00001 | $0.00442 |
Grade A, and why
disprove 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 300 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Lean4 Disprove
Search for a counterexample to a target proposition and, when possible,
produce a Lean proof of its negation. Reports REFUTED only when Lean
certifies the refutation; otherwise WITNESS_UNCERTIFIED (a candidate was
found but Lean refused to certify it) or INCONCLUSIVE (no candidate
found within budgets).
/lean4:disprove is always interactive — disprove is an exploratory
search, and the workflow generates three dynamic menus each cycle
(Step 0 knowledge search, Step 1 method, Step 2 config) seeded by
accumulated evidence and the Target Profile.
Usage
/lean4:disprove Foo.lean:42 # File + line (sorry/declaration site)
/lean4:disprove MyNs.SubNs.myThm # Qualified theorem name
/lean4:disprove Foo.lean:42 --max-cycles=5
/lean4:disprove Foo.lean:42 --commit=never
Prime Directive
Report REFUTED only when a Lean term of the negation typechecks under
lake env lean with no sorry or admit and its axiom set is within the
allowed whitelist (propext, Classical.choice, Quot.sound; plus
Lean.ofReduceBool only under an explicit native_decide opt-in this cycle).
Fast witnesses and informal heuristics are hypotheses until Lean certifies
them. See
disprove-engine.md § Prime Directive.
REFUTED is licensed by a checked closed term of type ¬ TARGET, not by the
artifact's surface form: T_counterexample may be a direct ¬ TARGET theorem or
a witness theorem whose named per-shape wrapper (also axiom-checked) derives
¬ TARGET.
Invocation Contract
Interpret this command's inputs per the Command Invocation Contract.
Primary path (hook-validated): If a validated-invocation block for this
command appears in context, treat it as the authoritative interpretation of
parser-decidable inputs and do not re-parse the raw invocation text for
those inputs. Start by reading all parser-decided fields from the block. Emit
the final Resolved Inputs summary from the block values.
See Validated Invocation Block.
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.
- 6d ago First seen · 300 lines · 12 tokens per session scan A 6ecd7a347051
disprove is a command published in the GitHub repository cameronfreer/lean4-skills (430 stars, last pushed yesterday), licensed MIT. It adds 12 tokens to every session and 4,418 once invoked, about $0.0001 per session on Opus 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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