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.
npx agentmods add skills/caffeinelabs/skills/extension-object-storagenpx skills add caffeinelabs/skills --skill extension-object-storagegit clone --depth 1 https://github.com/caffeinelabs/skillsWrote 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/caffeinelabs/skills/extension-object-storage)<a href="https://agentmods.dev/skills/caffeinelabs/skills/extension-object-storage"><img src="https://agentmods.dev/badge/skills/caffeinelabs/skills/extension-object-storage.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 | $0.00055 | $0.02090 |
| Opus 5 | $0.00028 | $0.01045 |
| Sonnet 5 | $0.00011 | $0.00418 |
| Haiku 4.5 | $0.00006 | $0.00209 |
Grade A, and why
extension-object-storage 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 5d 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 — 223 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Object Storage
Object storage extension for Caffeine AI.
Overview
This skill adds off-chain file/object storage with on-chain references. The MixinObjectStorage mixin provides infrastructure for file operations; you track uploaded files in your own data structures using Storage.ExternalBlob.
Required Setup Checklist
All four steps are mandatory. Skipping any one causes 403 Forbidden: Invalid payload at upload time.
- mops dependency — add
caffeineai-object-storagetomops.tomlunder[dependencies]. - Mixin invocation —
include MixinObjectStorage()inmain.mo(imported from"mo:caffeineai-object-storage/Mixin"). - Storage.ExternalBlob types — every data field that represents a file MUST use
Storage.ExternalBlob, neverText. - Frontend npm package —
@caffeineai/object-storageinstalled andExternalBlob.fromBytes(bytes, file.type, file.name)used at the call site.
CRITICAL: The frontend package (@caffeineai/object-storage) does NOT work without the backend mops package (caffeineai-object-storage). Installing only the npm package and not the mops package causes silent upload failures (403 from the storage gateway). You MUST install both together.
Backend
File content is stored off-chain. The backend manages references to external files using the Storage.ExternalBlob type from mo:caffeineai-object-storage/Storage. The frontend handles the actual upload/download; the backend only stores the reference.
CRITICAL: ANY data field that represents a file, image, photo, document, or media MUST use Storage.ExternalBlob as its type -- NEVER Text. Using Text breaks the upload/download proxy. Method parameters that accept file uploads MUST also use Storage.ExternalBlob, not Text.
Correct:
blob : Storage.ExternalBlob
Wrong:
blobId : Text
imageUrl : Text
fileRef : Text
Module API
The only type you use from mo:caffeineai-object-storage/Storage is ExternalBlob (which is Blob). All other functions in Storage.mo are internal infrastructure used by MixinObjectStorage -- do not call them directly.
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.
- 5d ago First seen · 223 lines · 55 tokens per session scan A 7818a7b1ff0e
extension-object-storage is a skill published in the GitHub repository caffeinelabs/skills (0 stars, last pushed yesterday), licensed Apache-2.0. It adds 55 tokens to every session and 2,090 once invoked, about $0.0003 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 2026-08-31.
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