Active Storage Validations is a Ruby gem for adding validation rules to files attached through Rails Active Storage. Rails developers use it to check whether uploaded images, videos, audio files, PDFs, and other attachments meet requirements such as type, size, dimensions, duration, or quantity.
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.
git clone --depth 1 https://github.com/igorkasyanchuk/active_storage_validationsWrote 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/rules/igorkasyanchuk/active_storage_validations/spec)<a href="https://agentmods.dev/rules/igorkasyanchuk/active_storage_validations/spec"><img src="https://agentmods.dev/badge/rules/igorkasyanchuk/active_storage_validations/spec/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/rules/igorkasyanchuk/active_storage_validations/spec"><img src="https://agentmods.dev/badge/rules/igorkasyanchuk/active_storage_validations/spec.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 | $0.00000 | $0.00548 |
| Opus 5.5 | $0.00000 | $0.00219 |
| Sonnet 5.5 | $0.00000 | $0.00110 |
| Haiku 4.5 | $0.00000 | $0.00055 |
Grade A, and why
spec 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 1mo 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
Spec conventions
- Boot via
rails_helper/.rspec; preferdescribed_classover repeating the described constant. - Always use a named
subject— never anonymoussubject { ... }/subject do. - Prefer referencing the name in expectations (
expect(metadata)), not baresubject. Shared helpers underspec/**/support/may callsubject(aliases any named subject);RSpec/NamedSubjectdoes not scan helper methods. - Prefer these names (avoid clashing with an existing
letof the same name — that causes recursion):
| Situation | Name |
|---|---|
Fresh model (Something.new) |
subject(:model) |
Model after attach(...) (body uses let(:model)) |
subject(:record) |
| Matcher / chained matcher API | subject(:configured_matcher) |
Analyzer #metadata / #content_type |
subject(:metadata) / subject(:content_type) |
| Other return values | descriptive name (:result, :html, :valid, …) |
# good
subject(:metadata) { analyzer.metadata }
subject(:record) { model.avatar.attach(file) and model }
subject(:configured_matcher) { matcher.allowing("image/png") }
expect(metadata).to eq({})
expect(record).to be_valid
# bad
subject { analyzer.metadata }
expect(subject).to eq({})
- Use
describefor named units/topics (#metadata,:less_than,"one","several","Edge cases","working with …") andcontextfor situations (when …,with …,without …, nestedand …/which …/that …/but …). Nevercontext "one"— that is a topic, sodescribe "one". - Prefer
let/beforefor setup; keepitdescriptions as outcomes, not conditionals already expressed by the surroundingcontext. - Open dummy fixtures with
open_fixture/fixture_file(orregister_fixture_io/register_uploaded_filefor Tempfile and upload wrappers). Do notFile.openfixture paths and leave them for GC;config.aftercloses registered IOs only. - Domain rules:
spec-validators.mdc,spec-matchers.mdc,spec-analyzers.mdc,spec-integration.mdc.
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.
- 1mo ago Changed · +1 lines 12185f081daa
- 1mo ago First seen · 39 lines · 0 tokens per session scan A 15df2e83342f
spec is a cursor rule published in the GitHub repository igorkasyanchuk/active_storage_validations (1,193 stars, last pushed 2d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 548 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 2026-08-30.
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