> ## Documentation Index
> Fetch the complete documentation index at: https://docs.artbucket.io/llms.txt
> Use this file to discover all available pages before exploring further.

# 0002: Content-addressed storage; renditions are a function of the URL

> Accepted, v0.1.

## Context

Exports, download dialogs and rendition jobs are where most DAMs make people
and scripts wait. Duplicate uploads are where they waste the most storage.

## Decision

* An original is stored once, under its SHA-256 (`assets/{sha256}`), however
  many workspaces hold it. Uploading the same bytes twice is a no-op.
* A rendition is named by its URL: `/a/{id}/w_800,f_webp`. It is made on the
  first request, with sharp, cached to the bucket, and served from there after.
  The transform grammar is a strict whitelist with hard caps.

## Consequences

* An agent builds the URL it needs without asking anything first.
* No job queue: the first request for a size pays for it once.
* Deleting bytes needs care, since several rows may hold them: the sweeper
  removes an original only when no row anywhere does, under the lock an
  upload of the same bytes takes.
* A rendition's p99 is a request's latency. When that hurts, a queue is the
  trigger (see Deferred in the roadmap).