Editor image uploads via Blossom (4 public servers) - #9
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Adds public/js/blossom.js — click the image button, drag, or paste an image and it uploads to public Blossom servers (blossom.band primary + BUD-04 mirror to blossom.nostr.build / nostr.download / cdn.nostrcheck.me) and inserts the markdown. Auth is a NbreadSigner-signed kind-24242 event; the returned URL is validated as a clean https:// destination before it's spliced into the post (rejects markdown-breakout chars). Uploads reuse the in-page signers (extension / NIP-46 / pasted key); the Amber NIP-55 redirect signer falls back to the URL template. All inserts go through the existing execCommand undo seam.
Opens connect-src to the four Blossom origins so browser uploads reach them; script-src and every other directive are unchanged, and BLOG_CSP (blog subdomains, JS-free) is untouched. img-src * already covered displaying the results.
This was referenced Jul 18, 2026
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Adds image upload to the editor. Click the image button, drag, or paste an image and it uploads to public Blossom servers and inserts the markdown — no more hand-pasting URLs.
How
public/js/blossom.js— uploads a NbreadSigner-signed kind-24242 Blossom auth event + the raw blob viaPUT /uploadto blossom.band (primary, indefinite retention), then BUD-04 mirrors to blossom.nostr.build / nostr.download / cdn.nostrcheck.me for redundancy. All four were live-probed (real anonymous signed upload + CORS preflight) before selection.execCommandseam, so native undo survives; an![uploading…]()placeholder is swapped for the finalon success.connect-srcopens to exactly those fourhttps://origins.script-srcand every other directive are unchanged; BLOG_CSP is untouched (blog subdomains stay JS-free);img-src *already displayed the results.Security
Adversarially reviewed (CSP-regression, upload/secret handling, editor UX). Fixes applied:
https://evil/x.png) [phish](…)to escape; the returned URL is rejected if it contains whitespace,(),<>, quotes, or backtick, on top of thehttps://-only check.textContent.Known low-severity, accepted: the returned image host isn't pinned to the upload server (harmless — an https image under
img-src *), and the optional sha256 integrity check is skipped if a server omits it.Durability caveat (Approach A)
Images live on public servers, hedged by 4-way mirroring, not first-party-durable — the tradeoff of attaching public servers vs. running our own R2 Blossom. Content-addressing means any mirror can re-serve a blob by its sha256 if one dies.
Testing
856/856 tests (45 files);
wrangler deploy --dry-rungreen; vendor drift clean. Newtest/unit/blossom.spec.tscovers the pure helpers (auth-event shape, base64url encoding, file validation, URL validation).docs/manual-signer-tests.md§9 covers the real-device upload path.