Borrowing it
Nothing to install: this file belongs to Lengros/bennu. 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/Lengros/bennu/main/.claude/skills/sprite-anim/SKILL.mdgit clone --depth 1 https://github.com/Lengros/bennuWrote 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/lengros/bennu/sprite-anim)<a href="https://agentmods.dev/skills/lengros/bennu/sprite-anim"><img src="https://agentmods.dev/badge/skills/lengros/bennu/sprite-anim/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/lengros/bennu/sprite-anim"><img src="https://agentmods.dev/badge/skills/lengros/bennu/sprite-anim.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 | $0.00102 | $0.01451 |
| Opus 5.5 | $0.00041 | $0.00580 |
| Sonnet 5.5 | $0.00020 | $0.00290 |
| Haiku 4.5 | $0.00010 | $0.00145 |
Grade A, and why
sprite-anim 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 — 104 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/sprite-anim — sprite frames & browser-verified animation
Two capabilities that recur together when polishing a sprite-driven UI animation: (A) make a set of frames look like one consistent character, and (B) prove the animation actually behaves on screen — not just in the code. Both ship as runnable scripts beside this file; the gotchas that make them non-obvious live in two lessons.
The cardinal rule for both: a code read is not evidence about pixels. Re-measure the output, and verify motion in a real browser. The session that produced this skill burned an iteration dismissing real drift as a "measurement artifact" — don't.
A — Normalize sprite frames to a uniform character size
When: frames of the same character render at visibly different sizes or bob vertically as the animation cycles (sitting frame bigger than running frame; feet at different heights).
Two choices, each with a wrong-looking default:
- Size by silhouette AREA, not bbox height/width. Area is pose-robust — a crouched
or stretched pose holds the same "amount of character" as a tall one. Scale each frame
by
sqrt(medianArea / frameArea). Height-normalizing inflates low/wide poses into giants. Clamp the factor (default[0.70, 1.45]) so a folded pose (curled sleeper = little area) doesn't blow up, and re-clamp to the canvas. - Align the bbox BOTTOM to a baseline, not center. Centering puts feet at different
heights → the character bobs frame-to-frame. Seat every bbox bottom on one baseline.
Pick the baseline to match the render's
transform-origin(e.g.50% 85%→ feet near bottom → baseline low on the canvas).
Run:
python3 .claude/skills/sprite-anim/normalize_frames.py SRC_DIR DST_DIR \
[--clamp LO HI] [--baseline auto|N] [--align-x center|N] [--pad N]
Canvas size is preserved per frame, so the render's object-fit math is untouched. Write
to a scratch DST first, verify, then copy into the repo's frames dir (in a worktree, per
the code-changes-go-to-worktree rule).
What ships with it
2 files 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 · 104 lines · 102 tokens per session scan A e402fe85970f
sprite-anim is a skill published in the GitHub repository Lengros/bennu (2 stars, last pushed 3mo ago), licensed MIT. It adds 102 tokens to every session and 1,451 once invoked, about $0.0004 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 2026-08-31.
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