VoxVera/docs/nostr-static-client-spec.md

VoxVera Nostr Static Client Spec

Status: main is the Nostr static-client branch. The legacy Tor/OnionShare CLI version is preserved on legacy-tor.

Goal

VoxVera should let anyone publish, fetch, and print flyer content without a centralized application server.

The static client is responsible for:

• rendering the flyer
• generating QR codes
• authoring a normalized Nostr flyer payload
• generating anonymous browser-side Nostr keys
• signing and publishing replaceable Nostr events
• fetching events by raw event ID, note1, nevent1, or naddr
• rendering fetched content safely

Nostr relays store the flyer source content. Static hosts only serve the client.

Active Files

site/
  index.html          (the client)
  nostr-client.css
  nostr-client.js
  locales.js
  board.html          (bulletin board page)
  board.js
  favicon.svg         (inline SVG site icon)
  CNAME
  vendor/
    nostr-tools/
    qrcode-generator/
  nostr/
    index.html        (redirect stub for legacy /nostr/ URLs)
voxvera/
  nostr/
    schema.py
tests/
  test_nostr_schema.py

Deployment

The deployable static root is site.

No build command is required. Vercel should use:

• root directory: repository root
• output directory: site
• build command: empty

The client is served from the root (site/index.html). site/nostr/index.html is a redirect stub that forwards the legacy /nostr/ path to the root, preserving the query string and #naddr fragment, so poster URLs and QR codes printed before the move still resolve.

Event Model

Recommended event kind: 30078 parameterized replaceable event.

Required tags:

• ["d", "voxvera:<slug>"]
• ["t", "voxvera"]
• ["t", "flyer"]

Recommended language tags:

• ["language", "<lang>"]
• ["L", "ISO-639-1"]
• ["l", "<lang>", "ISO-639-1"]

The payload lang field is authoritative. The language tags exist for relay/search metadata and as a fallback for older events whose payload omitted lang.

Payload:

{
  "type": "voxvera_flyer",
  "version": 1,
  "folder_name": "voxvera",
  "name": "Vox Vera Printable Flyers",
  "lang": "en",
  "title": "OPERATION VOX VERA",
  "subtitle": "DO ~~NOT~~ DISTRIBUTE",
  "headline": "TOP SECRET",
  "content": "Flyer body text",
  "url_message": "Follow this link to learn more.",
  "url": "https://creator.example/action",
  "tear_off_link": "https://voxvera.org/nostr/#naddr1...",
  "footer_message": "0110010",
  "qr_target": "flyer_url"
}

The UI labels folder_name as Flyer Name; it acts as the event slug, not a local hosting folder.

QR Target

Default behavior: qr_target: "flyer_url".

url is always the creator-controlled content destination shown in the body of the flyer. The editor must not overwrite this field with generated app URLs.

When publishing, the client computes the replaceable-event naddr and writes the generated poster URL to tear_off_link. The tear-off tabs and tear-off QR code point at tear_off_link, so people can re-open and reprint the flyer. The main flyer QR code points at url, so viewers can visit the creator's intended destination.

Each tear-off tab is labeled with the flyer's title (.tear-off-title, auto-sized by fitTabTitles() to be as large as fits the ~1in tab, shrinking rather than overflowing for long titles), a clickable "Open & reprint this flyer" link (tab_link, the <a href> so it stays live in a printed PDF), the tear-off QR, and a "Reopen at VoxVera.org — Event ID:" line (tab_event_id, the brand stays Latin; the rest is localized) with the full event id. All strings are translated in every supported language.

The naddr is encoded with a single relay hint (the primary configured relay) instead of the full relay list. This keeps the poster URL short and its tear-off QR code easy to scan — a typical poster URL drops from ~233 characters (full list) to ~171 — while still pointing a fresh viewer at a relay that has the event. Viewers also fall back to DEFAULT_RELAYS, which is where flyers are published by default. This stays a standard NIP-19 naddr, so any Nostr client can resolve it, and older relay-bearing naddr URLs continue to decode and resolve unchanged.

The naddr is carried in the URL fragment (#naddr1...) rather than a ?addr= query parameter. The fragment is shorter (less QR clutter), needs no URL-encoding, and never reaches the static host. getUrlEventReference reads the naddr from query params, the fragment, or anywhere in the full URL, so older ?addr= poster URLs and printed QR codes still resolve.

Supported values:

• flyer_url: tear-off QR points to the hosted client URL for the poster
• content_url: QR points to the payload's content URL
• nostr_event: QR points to the Nostr source identifier when available

Safety

Nostr content is untrusted.

The client and schema helper must:

• reject raw HTML in flyer text fields
• escape rendered flyer content
• reject unsafe URL schemes such as javascript: and data:
• keep attachments unsupported in V1
• avoid remote frontend dependencies

Publishing identity

The editor signs flyer events under one of four identities, chosen in the identity controls (activeIdentity / signActiveEvent in nostr-client.js):

• Anonymous (default). The per-device key in localStorage (voxvera_nostr_anon_secret_hex); signs locally with finalizeEvent. Unchanged behavior — no connection required. "Generate anonymous npub" rolls a fresh device key.

• Browser extension (NIP-07). Signs via window.nostr.signEvent; the secret never enters the page. The pubkey is fetched with getPublicKey().

• Private key (nsec). The user pastes an nsec; it is decoded to a secret key used to sign with finalizeEvent. By default the secret lives only in memory for the session. If the user ticks "Remember on this device", the secret is encrypted with a PIN and stored as voxvera_identity_nsec_enc; the plaintext secret is never written to storage.

• Remote signer (NIP-46). The user's real secret never reaches the browser; the client mints an ephemeral local key and exchanges encrypted kind-24133 JSON-RPC requests (connect → get_public_key → sign_event) over a raw WebSocket. Two connect paths are offered:

  • bunker:// (paste). The user pastes a link the signer app generated; the client connects out to that bunker relay.
  • nostrconnect:// (QR). The client generates the link itself, renders it as a QR (makeQrSvg) plus a copyable link, and listens on a rendezvous relay (relay.nsec.app); the signer app scans it and connects back, proving the connection by echoing the client's random secret. The discovered signer pubkey is then used for the durable connection.

  Requests are encrypted with NIP-44 (with a NIP-04 decrypt fallback for older signers); the vendored nostr-tools bundle has no nip46 module, so this client is hand-rolled. The connection is session-only — nothing is persisted, so a reload returns to anonymous.

The chosen mode is remembered in voxvera_identity_mode (and the npub in voxvera_identity_npub for display). On reload: NIP-07 re-fetches the pubkey; a remembered nsec shows a locked state until the PIN is entered (unlock); a session-only nsec or a remote-signer session falls back to anonymous. naddr/poster-URL/author npub outputs all reflect the active identity. A deliberate identity choice is also mirrored to voxvera_connected_pubkey so the bulletin board reflects the same identity.

PIN encryption details. PBKDF2 (SHA-256, 600k iterations, random 16-byte salt) derives an AES-GCM-256 key (random 12-byte IV); the blob stores {v, iters, salt, iv, ct} base64. A minimum 4-digit numeric PIN is enforced, but longer PINs are allowed and encouraged.

Security caveat (documented deliberately). A short numeric PIN has a tiny keyspace (a 4-digit PIN is ~10,000 combinations), so if the encrypted blob is exfiltrated (targeted XSS, or devtools access on a shared/stolen device) it is brute-forceable offline regardless of PBKDF2 cost. PIN-at-rest protects against casual snooping and untargeted localStorage scraping, not a determined or targeted attacker. The NIP-07 extension path (secret never in the page) and the NIP-46 remote signer (secret stays in the signer app; the browser holds only an ephemeral key — paste a bunker:// link) are the stronger options. See roadmap.md.

Editing, re-publishing, and deleting flyers

Because flyers are addressable replaceable events (kind 30078, identified by (pubkey, d) where d = voxvera:<slug>), the author can manage a published flyer by re-publishing under the same key + Flyer Name. When a flyer is loaded from an event, the editor shows author-only actions (#loaded-flyer-actions):

• Edit — change fields and publish again; the same d tag replaces the prior version in place, keeping the same naddr/poster URL.
• Re-publish (keep-alive) — re-sign and re-broadcast the current content so relays that prune app-data don't age the flyer out (republishCurrentFlyer).
• Delete (deleteLoadedFlyer) — two layers, for robustness across relays:
  1. a replaceable tombstone (buildTombstoneEvent) — same (kind, d), with deleted: true in the payload and a ["deleted"] tag, so it overwrites the flyer's content; relays honoring replaceable semantics now serve the tombstone, and
  2. a NIP-09 deletion request (buildDeletionEvent, kind 5) referencing the addressable a tag (30078:<pubkey>:voxvera:<slug>) and the event id, asking relays to drop it entirely.

All three are author-only: the active signing key must match the loaded flyer's author (resolveActivePubkey), and signAndPublish refuses to publish if the signed key diverges from the address. Tombstone recognition: the board's parseFlyers keeps the newest event per (pubkey, d) and skips it if that newest version is a tombstone (so a delete can't be undone by an older copy arriving later); the viewer shows a localized "This flyer was removed." state (isFlyerTombstone). Deletion is best-effort — relays that ignore both replaceable overwrites and NIP-09 may still serve the original — so it is framed as a request, not a guarantee.

Importing and exporting a flyer design

The editor can save and load a flyer design as a portable .json file (Export design / Import design), independent of publishing. The file format is { type: "voxvera_flyer_design", version: 1, flyer: <payload>, relays: [] }, where flyer is exactly rawPayloadFromForm() — the content fields plus the relay list, and nothing identity-bound: no npub, naddr, event id, or signature (all of those are derived at publish time by withPosterUrl / signAndPublish). That makes a design portable: it can be handed to anyone and published under their key with a fresh address.

• Export (exportDesign) serializes the current form as-is (draft-friendly, no strict validation) and downloads <folder_name>-voxvera-design.json.
• Import (importDesignFromFile) reads the picked file (capped at 256 KB), JSON.parses it, and accepts either the wrapper format or a bare voxvera_flyer payload (readDesignFile, lenient). It then shows a confirm modal (#import-modal) before overwriting the editor, and on confirm (applyPendingImport) fills the form via fillEditorFromConfig and restores the relay list. Imported content is untrusted, but it flows through the lenient view path (the renderer escapes every field) and still faces strict validatePayload at publish (raw-HTML rejection, length caps, URL schemes).

This replaced the earlier raw "Export event JSON" button; the published (signed) event JSON is still shown in #event-json-output after a publish.

Print paper size

The flyer supports two print sizes: US Letter (8.5×11in) and A4 (210×297mm), covering every country whose language the client supports (Letter in North America and a few Latin American countries; A4 everywhere else, including the EU, Russia, China, Japan, and the Middle East).

• Dimensions live in CSS custom properties --sheet-w / --sheet-h, switched by a paper-letter / paper-a4 class on <html> (applyPaperSize in nostr-client.js). The tear-off column (3.75in) and QR codes (1.25in) stay fixed physical sizes; the content column flexes to the sheet width.
• The print @page { size: … } is injected by JS (an element with id voxvera-page-size), because @page size cannot read CSS custom properties across engines. The static @media print block keeps margin: 0 and a Letter default for the pre-JS state.
• The default is chosen from the region subtag of the browser locale (preferredPaperSize — e.g. en-GB → A4, en-US → Letter). This is "by location" without geolocation, using the same signal as language. When no locale carries a region, it falls back to Letter.
• A user override (the paper-size selector) is stored in localStorage (voxvera_paper) and wins over the region default.
• Paper size is a local print/view preference and is never written into the Nostr event. A flyer authored on Letter reprints on A4 for a European viewer without changing the source event. The live fit-check protects authoring on whichever size is active; switching to a narrower size after authoring can ellipsis-truncate a maxed-out single-line field.

Field capacity therefore varies by paper size; see flyer-field-limits.md.

Bulletin board

site/board.html + site/board.js are a standalone page that lists the most recent flyers found on the default relays as a sortable, spreadsheet-style table: title, link (the poster URL, rendered as the word "link"), posting npub, language, posted date, and the event ID (shown shortened, full value in the title attribute, with a per-row copy button). Any column header sorts (default is date descending); replaceable events are de-duplicated per author+d identifier, keeping the latest.

• The entry point is a small screen-only link below the flyer preview (.board-link, label bulletin_board), outside the printable sheet. It must never print (hidden in the @media print block alongside the other app chrome).
• The board is gated behind a connected Nostr identity. On load it shows a login gate (#board-gate) instead of the table, with four ways to connect: a NIP-07 extension (window.nostr.getPublicKey()), a NIP-46 remote signer (either paste a bunker:// link or scan a nostrconnect:// QR; same hand-rolled client as the editor — it establishes the viewer pubkey via get_public_key and keeps the connection so getBoardSigner can sign reports/deletes remotely this session, then falls back to read-only after a reload), pasting an nsec (decoded in-page to derive the pubkey, then discarded — the secret is never stored or transmitted), or creating a new key (reuses this device's anon key in voxvera_nostr_anon_secret_hex if present, else generates one, and reveals the nsec with a save-it warning before continuing). On success it reveals the table and surfaces the connected npub (#board-identity) with a Disconnect control. The board only ever needs the pubkey to view (it reads to filter), so the connected pubkey is remembered in localStorage (voxvera_connected_pubkey, shared with the main client) and a return visit reconnects from it directly — no prompt or re-entry, any method. This is not access control — the events are public on the relays regardless — it establishes the viewer's identity for the web-of-trust filter below. Authoring and printing flyers stays fully anonymous and never requires connecting.
• Web-of-trust filter (NIP-02). Once connected, the board fetches the viewer's contact list (kind 3) and defaults to showing only flyers whose author is in the viewer's follow graph (degree 1) plus the viewer themself. A "Show all" checkbox opts out to the full relay firehose. A viewer with no follow list of their own (a fresh key) is seeded from a pinned curator account's follows (FALLBACK_CURATOR_PUBKEY in board.js), so a brand-new viewer still gets a curated board. If no trust data can be fetched at all, the board falls back to showing everything so it is never mysteriously empty. The #board-filter-note explains which mode is active (following / seeded / all), and re-localizes with the language selector. See roadmap.md for the phased plan (Phase 1 = the gate; Phase 2 = this filter; Phase 3 = degree-2 trust, blocklist/report, NIP-05 badges).
• board.js is independent of nostr-client.js (which exports nothing), so its UI strings live in BOARD_UI (all supported languages); it reuses the vendored nostr-tools and locales.js (for language names + RTL direction).
• The board has its own language selector. It reads/writes the same voxvera_nostr_lang localStorage key as the main client, so the chosen language carries across both pages, and switching it re-localizes the chrome, column headers, language labels, and date formatting (and flips RTL).
• Relay content is untrusted: titles and npubs are escaped, and link URLs are rejected unless http:/https: (so javascript:/data: never render as a link).
• The npub column is forward-looking — anonymous keys today, but a stable identity per author maps cleanly onto this view later.
• Per-row actions (behind a per-row ⋯ menu). On flyers the connected viewer authored, the menu offers Edit (a link to /?edit=1#<naddr>, which loads the flyer in the editor), Re-broadcast (re-sends the already-signed event to all relays — no signing needed), and Delete (tombstone + NIP-09; the board signs via the device key or NIP-07, and for a pasted-nsec connection it points to the editor). On flyers from others it shows Block — a per-device blocklist of author pubkeys (voxvera_blocked_pubkeys) that always hides them, with a "Clear blocked" control. The blocklist is local "hide this," separate from the web-of-trust filter (roadmap #1).
• Narrow screens (≤640px): the table collapses to a card per flyer — the title and the ⋯ menu stay visible, and the secondary fields (link, posted-by, language, date, event id) sit behind a per-row Details disclosure (.board-details-toggle toggles tr.expanded; the columns become labeled rows via their data-label).

On mobile the flyer preview scales to fully fit the screen width (updatePreviewScale / --flyer-preview-scale): the sheet keeps its true print width (flex: 0 0 auto, so the viewer-mode flexbox doesn't shrink it) and is visually scaled with a transform — so it never side-scrolls or clips.

The login gate (Phase 1) and the web-of-trust filter (Phase 2) are in place. Remaining gaps — degree-2 trust, a blocklist/report flow, NIP-05 badges, and making the bootstrap curator configurable — are tracked in roadmap.md.

Localization

Flyer defaults come from site/locales.js.

Nostr editor/viewer controls and Nostr-specific flyer labels come from NOSTR_UI in site/nostr-client.js.

Language changes should:

• publish the selected flyer language in payload lang
• publish matching Nostr language tags
• infer language from event tags if a fetched payload omits lang
• update default flyer content while the flyer is still using default content
• preserve user-authored or fetched event content
• update editor/viewer tool labels
• update printed side-tab labels
• respect RTL direction metadata

Letter-spacing by script

Flyer text uses tighter letter-spacing than the original design to fit more characters per line, but letter-spacing is not script-neutral, so it is applied per script via a policy class on the flyer .container (LETTER_SPACING_POLICY in nostr-client.js; ls-full / ls-cjk / ls-none rules and --ls-* variables in nostr-client.css):

• full — Latin, Cyrillic, Hebrew: reduced positive tracking on the display fields plus a slight negative on body/URL to reclaim line width.
• cjk — Japanese, Chinese: tracking is clamped to 0 and never negative, so full-width glyphs do not overlap.
• none — Arabic, Persian, Hindi: letter-spacing is turned off entirely. These are cursive or complex scripts where any tracking breaks the letter joins or detaches combining marks. (This also corrected the prior behavior, which applied the design's display tracking to every language unconditionally.)

When adding a language, classify its script in LETTER_SPACING_POLICY (default is full) and verify the headline, subtitle, and body render correctly in the browser.

Verification

node --check site/nostr-client.js
pytest -q

For UI work, also verify browser rendering and print output from a local static server.