Borrowing it
Nothing to install: this file belongs to gridaco/nothing. 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/gridaco/nothing/main/.agents/skills/render-reftest/SKILL.mdgit clone --depth 1 https://github.com/gridaco/nothingWrote 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/skills/gridaco/nothing/render-reftest)<a href="https://agentmods.dev/skills/gridaco/nothing/render-reftest"><img src="https://agentmods.dev/badge/skills/gridaco/nothing/render-reftest/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/skills/gridaco/nothing/render-reftest"><img src="https://agentmods.dev/badge/skills/gridaco/nothing/render-reftest.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 23 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Prompt Injection · line 842 Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
- high Privilege Escalation · line 1008 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- medium Memory Poisoning · line 31 Skill attempts to fill the context window with filler content, displacing legitimate instructions and safety constraints. This can degrade agent performance or bypass safety boundaries.Fix: Implement context-window management that detects and rejects padding or stuffing attempts. Prioritize system instructions over user-injected content.
- medium Prompt Injection · line 31 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 34 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 36 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 37 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 38 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 39 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 41 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 48 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium MCP Rug Pull · line 255 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium Prompt Injection · line 342 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 472 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 474 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 514 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 874 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 874 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 879 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 973 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
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 | $0.00071 | $0.13054 |
| Opus 5.5 | $0.00028 | $0.05222 |
| Sonnet 5.5 | $0.00014 | $0.02611 |
| Haiku 4.5 | $0.00007 | $0.01305 |
Grade A, and why
render-reftest 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.
How it starts
The opening of the file, as written. The whole thing — 1,141 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CG Rendering Tests — Reftests & Golden Tests
How to design, name, and review visual rendering tests in this repo.
When to Use This Skill
- Adding a new pixel-comparison test to
crates/grida/ - Reviewing a PR that adds or updates golden images
- Deciding whether a test should be a reftest, golden test, or probe test
- Designing a fixture that can be verified without vision input
- Investigating a flaky or platform-dependent visual test
- Setting up tolerance thresholds for image diff
- Writing honest PR descriptions for rendering changes
Terminology
Use these terms precisely. Misusing them erodes trust in test results.
| Term | Definition |
|---|---|
| Reftest | A test that compares renderer output against an independent reference (oracle) whose correctness is established outside this project — e.g. a W3C-provided PNG for an SVG test case. The oracle is the source of truth; a mismatch means our renderer is wrong. |
| Independent reference / oracle | A rendering produced by a separate, trusted implementation or defined by a specification. We do not control its content. |
| Golden test | A test that compares renderer output against a previously accepted snapshot produced by our own renderer. There is no external truth — the golden file is the expected output because a human reviewed and approved it. Also called a snapshot test. |
| Snapshot test | Synonym for golden test. The snapshot is a frozen output that we assert has not changed. |
| Render regression test | Any test whose purpose is to detect unintended changes in rendering output. Golden tests are regression tests. Reftests are correctness tests. |
| Pixel diff | Byte-level comparison of two raster images. A single differing channel value is a failure (at zero tolerance). |
| Perceptual diff | Comparison in a perceptual color space (e.g. YIQ via the dify crate). Weights differences by human visual sensitivity. More forgiving than raw pixel diff but still quantifiable. |
| rendiff | Rust crate (rendiff v0.2) for histogram-based pixel diffing. Computes a per-channel difference histogram; thresholds are expressed as [(max_diff, max_count), ...] pairs. Used in flatten_rendiff.rs for equivalence tests. Dep in crates/grida/. |
| dify | Rust crate for perceptual image comparison in YIQ color space. Used by grida_dev reftest for SVG reftests. Supports --threshold and --aa (anti-aliasing detection) flags. |
| pixelmatch | Pure-JS perceptual image comparison library. YIQ-based, AA-aware. Used by @grida/reftest. Zero native deps; same conceptual model as dify, slightly different threshold semantics — see parity notes below. |
@grida/reftest |
General-purpose, language-agnostic TS reftest CLI + library at packages/grida-reftest/. Takes two directories of PNGs, diffs, scores, writes the same bucket layout and JSON report as the Rust grida_dev reftest. Does NOT render anything — producers upstream. |
grida_dev reftest |
Rust reftest runner at crates/grida_dev/src/reftest/. SVG-specific: renders SVG via our own grida pipeline, then diffs against a reference PNG. Canonical for SVG. For non-SVG formats, use @grida/reftest with an upstream renderer. |
| refig | Short for "Figma reftest." Fixture suites under fixtures/local/refig/ containing .fig + document.json + images/ + exports/ (oracle PNGs from Figma's Images API). Consumed by a TS render step + @grida/reftest. See fixtures/local/refig/README.md. |
| refbrowser | Short for "headless-browser reftest." HTML/CSS fixtures under fixtures/test-html/L0/ rendered by Playwright Chromium as the oracle vs. our grida htmlcss renderer. Producer script: .agents/skills/render-reftest/scripts/refbrowser_render.ts; diff via @grida/reftest. |
| Tolerance / fuzz | A configured threshold below which pixel differences are ignored. Expressed as a histogram threshold (rendiff) or a YIQ distance (dify / pixelmatch). Required when rasterization is non-deterministic across platforms. |
| Data test | A test that asserts on the scene graph or computed values directly — no rendering needed. E.g. bounding box, resolved transform matrix, computed style. The cheapest possible assertion. |
| Probe test | A test that asserts correctness by reading pixel values at specific coordinates in the rendered output. Requires a purpose-built fixture with a minimal color palette and documented probe points. No full-image comparison needed. |
| Probe-friendly fixture | A fixture explicitly designed for probe testing: minimal colors, no decorative elements, shapes at known coordinates. Often accompanied by a .probe.json file declaring expected pixel values at specific points. |
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 · 1,141 lines · 71 tokens per session scan A c3b489858d4e
render-reftest is a skill published in the GitHub repository gridaco/nothing (54 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 71 tokens to every session and 13,054 once invoked, about $0.0003 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.
Other skills, from other repositories
check
Reviews diffs, PRs, release readiness, and publishing follow-through. Use when asked to review, triage issues or PRs, or ship. Not for debugging root causes or prose.
slides
Build a Grida slides deck — a .canvas bundle in slides mode whose pages are SVG documents (16:9, one SVG per slide). Use when creating a presentation, pitch deck, slideshow, or talk.
dotcanvas
Author and edit a Grida .canvas board — a .canvas.json manifest plus document files (references, generated images, notes) placed on an infinite canvas. Use when working on a .canvas bundle or arranging visuals/design work spatially. For a linear deck/presentation, use the slides skill instead.
svg
Author and edit .svg files in a Grida editor session — live-canvas binding, SVG output style, and parse-error recovery. Use when creating or modifying an SVG document.
write-pr
Reference standards for writing pull request titles and descriptions in the tldraw repository, plus the pre-flight comment sweep over the diff. Use as supporting guidance when another skill or workflow needs PR content standards, not as the user-facing create/update PR workflow.
pr-walkthrough
Create a narrated video walkthrough of a pull request with code slides and audio narration. Use when asked to create a PR walkthrough, PR video, or walkthrough video.