Condenser — Reference

The complete reference for the web front-end: its architecture, how it talks to the stack, the main views, configuration, and how signing works. For a gentle introduction, start with the Quick guide.

Condenser (blurt/condenser) is the React.js web interface to Blurt. It is a server-side-rendered single-page app: a Koa server renders the first response, and the browser hydrates and takes over.

Architecture

  browser  ◄──►  Koa SSR server  ──►  RPC proxy  ──►  nexus-go / blurtd
   React            (first paint,        (one URL)      (social / consensus)
   Redux + saga      sessions)

• React renders the UI. Redux holds application state; redux-saga runs all side effects — the RPC reads, transaction signing, and broadcasts.
• react-router resolves routes on both server and client (ResolveRoute, RootRoute).
• Koa is the SSR server: it renders the initial HTML, serves assets, and manages server sessions (keyed by SDC_SESSION_SECRETKEY).
• blurtjs (@blurtfoundation/blurtjs) is the chain client and crypto library — it builds, signs, and broadcasts transactions.
• i18n: the UI is translated into many locales through Translator and the locales/ catalogs.

The app code lives under src/app (components/, redux/, utils/, client_config.js, routing, and locales).

How it talks to the stack

Condenser never talks to a database or holds chain state; it uses one RPC endpoint and lets the RPC proxy fan the calls out:

• Browser calls go to SDC_CLIENT_BLURTD_URL; SSR server calls go to SDC_SERVER_BLURTD_URL. Both point at the RPC proxy.
• Social reads (feeds, communities, profiles, discussions) resolve to nexus-go; consensus reads and broadcasts go to blurtd.
• Drafts use a draft API endpoint (SDC_DRAFT_API_ENDPOINTS), served by nexus-go.
• Images are fetched through an image proxy (SDC_IMAGE_PROXY_PREFIX) and uploaded to an image service (SDC_UPLOAD_IMAGE_URL).

Signing and accounts

Keys never leave the user's device. Condenser signs transactions client-side with blurtjs and then broadcasts them through the proxy to blurtd. Users sign in with a posting key or through a keychain extension (e.g. WhaleVault); the front-end never sees or stores private keys server-side. The worst a compromised front-end can do is show wrong data — it cannot move funds without the user's key.

Main views

• Feeds — trending, hot, new, promoted, and per-community timelines.
• Post & comments — the discussion view with threaded replies and voting.
• Editor — markdown post/comment composer, with community targeting.
• Communities — community home pages, subscriber and role views.
• Profile — account pages (blog, posts, replies, wallet summary).
• Wallet views — balances, history, and transfers (the standalone wallet app is the dedicated tool).
• Notifications, search, settings.

Configuration

Condenser is configured with SDC_* environment variables (mapped in config/custom-environment-variables.json). The ones that wire it to a network:

Variable	Purpose
SDC_SESSION_SECRETKEY	server session secret; must stay constant across restarts
SDC_CLIENT_BLURTD_URL	RPC endpoint the browser uses (the RPC proxy)
SDC_SERVER_BLURTD_URL	RPC endpoint the SSR server uses
SDC_USE_APPBASE	use the appbase JSON-RPC calling convention
SDC_CHAIN_ID	chain id to sign against
SDC_ADDRESS_PREFIX	public-key address prefix (BLT)
SDC_DRAFT_API_ENDPOINTS	draft API (nexus-go)
SDC_ALT_API_ENDPOINTS	alternative RPC endpoints
SDC_IMAGE_PROXY_PREFIX / SDC_UPLOAD_IMAGE_URL	image proxy and upload service
SDC_PRICE_INFO_URL	price feed for wallet displays
SDC_COAL_URL / SDC_NSFW_URL / SDC_PHISHING_URL	moderation/safety lists
WALLET_URL / DAPPS_URL / SPECIAL_POSTS_URL	links to the wallet app and related surfaces

Base defaults live in config/default.json / config/production.json; the SDC_* variables override them at runtime.

Build and run

Condenser builds the React bundle and runs the Koa server (npm run build, then npm run production; npm start for development). It ships as a Docker image (registry.gitlab.com/blurt/blurt/condenser, plus an -arm64 variant). Provide a stable SDC_SESSION_SECRETKEY and point the SDC_*_BLURTD_URL variables at your RPC endpoint. See the repository for the current build and deployment details.

Where it fits

Condenser is the flagship read/write UI at the top of the stack. It consumes nexus-go and blurtd through the proxy — the same fusion every other page in this manual describes, seen from the browser's side: one URL in, the right backend serving each call.