Use quote-sats from btcdata instead of local EUR/BTC calculation

Sats value now comes from btcdata's Strike quote endpoint which
includes the actual fee/spread, matching the Strike app.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,5 @@
+target/
+node_modules/
+.env
+.cpcache/
+.nrepl-port

CLAUDE.md

@@ -1,15 +1,26 @@
 # btcprice
 
-Bitcoin price tracker - Clojure Kit web application.
+Bitcoin price tracker UI — Clojure Kit web application. Serves the HTML/Tailwind UI. Connects to btcdata for live price data via WebSocket.
 
 ## Build & Development Commands
 
-- `make run` — Start dev server on port 3000
+- `make run` — Start dev server on port 4000
-- `make repl` — Start nREPL on port 7888
+- `make repl` — Start nREPL
 - `make test` — Run tests
 - `make tailwind` — Watch Tailwind CSS for changes
 - `make uberjar` — Build production JAR
-- `docker compose up -d` — Start PostgreSQL
+- `docker compose up -d` — Start btcprice + btcdata containers
+
+## Docker
+
+Docker runs alongside local dev on different ports:
+
+| Service  | Local dev      | Docker         |
+|----------|----------------|----------------|
+| btcprice | localhost:4000 | localhost:4041 |
+| btcdata  | localhost:4100 | localhost:4101 |
+
+btcprice's docker-compose includes btcdata via `include: ../btcdata/docker-compose.yml`.
 
 ## REPL Commands
 
@@ -18,10 +29,6 @@ Bitcoin price tracker - Clojure Kit web application.
 (go)          ;; Start system
 (reset)       ;; Reload code & restart
 (halt)        ;; Stop system
-(reset-db)    ;; Drop & re-migrate database
-(migrate)     ;; Run pending migrations
-(rollback)    ;; Rollback last migration
-(query-fn)    ;; Get database query function
 ```
 
 ## Architecture
@@ -29,9 +36,10 @@ Bitcoin price tracker - Clojure Kit web application.
 - **Framework:** Kit (Integrant-based)
 - **Server:** Undertow
 - **Routing:** Reitit
-- **Templates:** Hiccup + HTMX
+- **Templates:** Hiccup + HTMX (WebSocket extension)
 - **Styling:** Tailwind CSS v4
-- **Database:** PostgreSQL + conman + Migratus
+- **Data backend:** btcdata (separate service at BTCDATA_URL, default http://localhost:4100)
+- **No database** — all data comes from btcdata
 
 ## Source Layout
 
@@ -50,6 +58,7 @@ src/clj/pmagnus/btcprice/
     │   └── formats.clj   # Content negotiation
     └── routes/
         ├── api.clj       # /api routes (JSON)
-        ├── ui.clj        # UI routes (HTML)
+        ├── ui.clj        # UI routes (HTML + HTMX WebSocket)
+        ├── ws_proxy.clj  # WebSocket proxy to btcdata
         └── utils.clj     # Route utilities
 ```

Dockerfile

@@ -1,14 +1,28 @@
-FROM clojure:openjdk-25 AS build
+FROM node:22-alpine AS css
 
 WORKDIR /build
-COPY . .
+COPY package.json package-lock.json ./
-RUN clj -Sforce -T:build all
+RUN npm ci
+COPY resources/css/ resources/css/
+COPY src/ src/
+COPY tailwind.config.js ./
+RUN npm run css:build
 
-FROM azul/zulu-openjdk-alpine:25
+FROM clojure:temurin-21-tools-deps-alpine AS build
+
+WORKDIR /build
+COPY deps.edn build.clj ./
+RUN clj -Sforce -P
+COPY . .
+COPY --from=css /build/resources/public/css/output.css resources/public/css/output.css
+RUN clj -T:build all
+
+FROM eclipse-temurin:21-jre-alpine
 
 COPY --from=build /build/target/btcprice-standalone.jar /btcprice/btcprice-standalone.jar
 
 EXPOSE 4040
 ENV PORT=4040
+ENV BTCDATA_URL=http://btcdata:4101
 
 CMD ["java", "-jar", "/btcprice/btcprice-standalone.jar"]

Makefile

@@ -1,7 +1,7 @@
 include .env
 export
 
-.PHONY: clean run repl tailwind test uberjar
+.PHONY: clean run run-docker repl tailwind test uberjar
 
 clean:
 	rm -rf target
@@ -9,6 +9,9 @@ clean:
 run:
 	clj -M:dev -e "(dev-prep!) (go)" -r
 
+run-docker:
+	BTCDATA_URL=http://localhost:4101 clj -M:dev -e "(dev-prep!) (go)" -r
+
 repl:
 	clj -M:dev:nrepl
 

README.md

@@ -0,0 +1,32 @@
+# btcprice
+
+Bitcoin price tracker UI. Serves an HTML page with live price updates streamed from [btcdata](../btcdata) via WebSocket using HTMX.
+
+## Quick Start
+
+```bash
+# Start btcdata first (provides price data)
+cd ../btcdata && make run
+
+# Local dev
+make run       # starts on port 4000
+make tailwind  # watch Tailwind CSS (separate terminal)
+
+# Docker (starts both btcprice + btcdata)
+docker compose up -d   # btcprice on 4041, btcdata on 4101
+```
+
+## Environment Variables
+
+| Variable | Default | Description |
+|---|---|---|
+| `PORT` | `4000` | HTTP server port |
+| `BTCDATA_URL` | `http://192.168.50.42:4100` | btcdata service URL (browser connects via WebSocket) |
+
+## How It Works
+
+The server renders an HTML page with HTMX and the WebSocket extension (`hx-ext="ws"`). HTMX connects directly to btcdata's WebSocket endpoint (`BTCDATA_URL/api/price/ws`), which sends HTML fragments. HTMX swaps the received `<div id="price-display">` into the DOM automatically. Price changes are color-coded (green up, red down). Reconnection is handled by HTMX with exponential backoff.
+
+## Tech Stack
+
+Clojure · Kit · Undertow · Reitit · Hiccup · HTMX · Tailwind CSS v4

deps.edn

@@ -1,7 +1,5 @@
 {:paths ["src/clj" "resources"]
  :deps {org.clojure/clojure                  {:mvn/version "1.12.3"}
-        org.clojure/data.json                {:mvn/version "2.5.1"}
-
         ;; Kit
         io.github.kit-clj/kit-core           {:mvn/version "1.0.6"}
 
@@ -28,11 +26,7 @@
         ;; Serialization
         metosin/muuntaja                     {:mvn/version "0.6.11"}
         luminus-transit/luminus-transit       {:mvn/version "0.1.6"}
-
+        org.clojure/data.json                {:mvn/version "2.5.1"}}
-        ;; Database
-        io.github.kit-clj/kit-postgres       {:mvn/version "1.0.7"}
-        io.github.kit-clj/kit-sql-conman     {:mvn/version "1.10.5"}
-        io.github.kit-clj/kit-sql-migratus   {:mvn/version "1.0.5"}}
 
  :aliases
  {:build {:deps {io.github.clojure/tools.build {:mvn/version "0.10.9"}}

docker-compose.yml

@@ -0,0 +1,15 @@
+networks:
+  btc-network:
+    name: btc-network
+    external: true
+
+services:
+  btcprice:
+    build: .
+    restart: unless-stopped
+    networks:
+      - btc-network
+    ports:
+      - "4041:4040"
+    environment:
+      BTCDATA_URL: "http://btcdata:${DOCKER_BTCDATA_PORT:-4102}"

env/dev/clj/user.clj

@@ -1,6 +1,5 @@
 (ns user
   (:require
-   [clojure.tools.logging :as log]
    [integrant.core :as ig]
    [integrant.repl :refer [go halt reset reset-all set-prep!]]
    [integrant.repl.state :as state]
@@ -19,30 +18,6 @@
      (-> (config/system-config {:profile :test})
          (ig/expand)))))
 
-(defn reset-db []
-  (let [sys (or @pmagnus.btcprice.core/system
-                integrant.repl.state/system)]
-    (when-let [mig (:db.sql/migrations sys)]
-      (migratus.core/reset mig)
-      (log/info "Database reset complete"))))
-
-(defn rollback []
-  (let [sys (or @pmagnus.btcprice.core/system
-                integrant.repl.state/system)]
-    (when-let [mig (:db.sql/migrations sys)]
-      (migratus.core/rollback mig))))
-
-(defn migrate []
-  (let [sys (or @pmagnus.btcprice.core/system
-                integrant.repl.state/system)]
-    (when-let [mig (:db.sql/migrations sys)]
-      (migratus.core/migrate mig))))
-
-(defn query-fn []
-  (let [sys (or @pmagnus.btcprice.core/system
-                integrant.repl.state/system)]
-    (:db.sql/query-fn sys)))
-
 (comment
   (dev-prep!)
   (go)

resources/migrations/20260217000000-create-binance-price.down.sql

@@ -1 +0,0 @@
-DROP TABLE binance_price;

resources/migrations/20260217000000-create-binance-price.up.sql

@@ -1,5 +0,0 @@
-CREATE TABLE binance_price (
-  id          BIGSERIAL PRIMARY KEY,
-  price       NUMERIC(18,8) NOT NULL,
-  recorded_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
-);

resources/migrations/placeholder.txt

@@ -1 +0,0 @@
-Migration files go here.

resources/queries.sql

@@ -1,9 +0,0 @@
--- queries for btcprice
-
--- :name insert-binance-price! :! :n
--- :doc Insert a Binance BTC price
-INSERT INTO binance_price (price) VALUES (:price)
-
--- :name get-latest-binance-price :? :1
--- :doc Get the most recent Binance BTC price
-SELECT price, recorded_at FROM binance_price ORDER BY id DESC LIMIT 1

resources/system.edn

@@ -32,27 +32,12 @@
  {:routes #ig/ref :router/routes
   :env    #ig/ref :system/env}
 
- :db.sql/connection
- {:jdbc-url #env JDBC_URL}
-
- :db.sql/query-fn
- {:conn        #ig/ref :db.sql/connection
-  :options     {}
-  :filename    "queries.sql"}
-
- :db.sql/migrations
- {:store            :database
-  :db               {:datasource #ig/ref :db.sql/connection}
-  :migrate-on-init? true}
-
  :reitit.routes/api
- {:base-path "/api"
+ {:base-path "/api"}
-  :query-fn  #ig/ref :db.sql/query-fn}
 
  :reitit.routes/ui
- {:base-path ""
+ {:base-path ""}
-  :query-fn  #ig/ref :db.sql/query-fn}
 
- :ws/binance
+ :reitit.routes/ws-proxy
- {:query-fn #ig/ref :db.sql/query-fn
+ {:base-path   ""
-  :uri      "wss://stream.binance.com:9443/ws/btcusdt@trade"}}
+  :btcdata-url #or [#env BTCDATA_URL "http://localhost:4100"]}}

src/clj/pmagnus/btcprice/core.clj

@@ -6,16 +6,12 @@
    [pmagnus.btcprice.env :refer [defaults]]
 
    ;; Edges
-   [kit.edge.db.postgres]
-   [kit.edge.db.sql.conman]
-   [kit.edge.db.sql.migratus]
    [kit.edge.server.undertow]
    [pmagnus.btcprice.web.handler]
    ;; Routes
    [pmagnus.btcprice.web.routes.api]
    [pmagnus.btcprice.web.routes.ui]
-   ;; WebSocket clients
+   [pmagnus.btcprice.web.routes.ws-proxy])
-   [pmagnus.btcprice.ws.binance])
   (:gen-class))
 
 (defonce system (atom nil))

src/clj/pmagnus/btcprice/web/htmx.clj

@@ -18,7 +18,8 @@
                    [:meta {:name "apple-mobile-web-app-status-bar-style" :content "black-translucent"}]
                    [:title (or (:title opts#) "BTC Price")]
                    [:link {:rel "stylesheet" :href "/css/output.css"}]
-                   [:script {:src "https://unpkg.com/htmx.org@2.0.8"}]]
+                   [:script {:src "https://unpkg.com/htmx.org@2/dist/htmx.min.js"}]
+                   [:script {:src "https://unpkg.com/htmx-ext-ws@2/ws.js"}]]
                   [:body
                    [:div.mx-auto.max-w-lg.px-4.py-6
                     ~@content]]]))}))

src/clj/pmagnus/btcprice/web/middleware/core.clj

@@ -2,8 +2,18 @@
   (:require
    [ring.middleware.defaults :as defaults]))
 
+(defn- wrap-nil-guard
+  "Discard responses with no :status — these are artifacts of ring-defaults
+   middleware wrapping a nil response (e.g., from a raw WebSocket upgrade).
+   Passes through :undertow/websocket responses for the adapter to handle."
+  [handler]
+  (fn [request]
+    (let [resp (handler request)]
+      (when (or (:status resp) (:undertow/websocket resp)) resp))))
+
 (defn wrap-base [{:keys [site-defaults-config]}]
   (fn [handler]
-    (cond-> handler
+    (-> handler
-      true (defaults/wrap-defaults
+        (defaults/wrap-defaults
-            (or site-defaults-config defaults/site-defaults)))))
+         (or site-defaults-config defaults/site-defaults))
+        (wrap-nil-guard))))

src/clj/pmagnus/btcprice/web/routes/api.clj

@@ -8,8 +8,7 @@
    [reitit.ring.coercion :as coercion]
    [reitit.ring.middleware.muuntaja :as muuntaja]
    [reitit.ring.middleware.parameters :as parameters]
-   [reitit.swagger :as swagger]
+   [reitit.swagger :as swagger]))
-   [reitit.swagger-ui :as swagger-ui]))
 
 (defn- api-routes [_opts]
   [["/swagger.json"

src/clj/pmagnus/btcprice/web/routes/ui.clj

@@ -1,40 +1,35 @@
 (ns pmagnus.btcprice.web.routes.ui
   (:require
    [integrant.core :as ig]
-   [pmagnus.btcprice.web.htmx :refer [page fragment]]
+   [pmagnus.btcprice.web.htmx :refer [page]]
    [pmagnus.btcprice.web.middleware.exception :as exception]
    [pmagnus.btcprice.web.middleware.formats :as formats]
    [reitit.ring.middleware.muuntaja :as muuntaja]
    [reitit.ring.middleware.parameters :as parameters]))
 
-(defn home-page [_req]
+(defn- home-page [_opts _req]
   (page {:title "BTC Price"}
     [:header.text-center.mb-8
      [:h1.text-3xl.font-bold.text-gray-900 "BTC Price"]
      [:p.text-sm.text-gray-500.mt-1 "Bitcoin price tracker"]]
 
-    [:div#price-panel.space-y-4
+    [:div#price-panel {:hx-ext "ws" :ws-connect "/ws/price"}
-     {:hx-get "/price" :hx-trigger "every 2s" :hx-swap "innerHTML"}
+     [:div#price-display
       [:div.bg-white.rounded-2xl.shadow-sm.border.border-gray-200.p-6
-      [:p.text-center.text-gray-400.text-sm "Loading..."]]]))
+       [:p.text-center.text-gray-400.text-sm "Connecting..."]]]]
 
-(defn price-fragment [{:keys [query-fn]}]
+    [:div.mt-4 {:hx-ext "ws" :ws-connect "/ws/strike"}
-  (let [row (query-fn :get-latest-binance-price {})]
+     [:div#strike-display
-    (fragment {}
       [:div.bg-white.rounded-2xl.shadow-sm.border.border-gray-200.p-6
-       (if row
+       [:p.text-center.text-gray-400.text-sm "Loading Strike rates..."]]]]
-         [:div.text-center
+
-          [:p.text-4xl.font-bold.text-gray-900
+    ;; Safelist classes used in btcdata HTML fragments
-           (str "$" (format "%,.2f" (double (:price row))))]
+    [:div {:class "hidden text-4xl text-2xl font-bold text-green-600 text-red-600 text-gray-900 text-xs text-gray-400 mt-2 flex justify-center justify-between items-center gap-4 mt-1 mt-3 text-sm text-gray-600 text-gray-500 mb-3 py-1 grid grid-cols-2 gap-x-6 gap-y-1"
-          [:p.text-xs.text-gray-400.mt-2
+           :aria-hidden "true"}]))
-           (str "Updated " (:recorded_at row))]]
-         [:p.text-center.text-gray-400.text-sm "Waiting for data..."])])))
 
 (defn- ui-routes [opts]
   [["/"
-    {:get home-page}]
+    {:get (fn [req] (home-page opts req))}]])
-   ["/price"
-    {:get (fn [_req] (price-fragment opts))}]])
 
 (defn route-data [opts]
   (merge

src/clj/pmagnus/btcprice/web/routes/ws_proxy.clj

@@ -0,0 +1,159 @@
+(ns pmagnus.btcprice.web.routes.ws-proxy
+  (:require
+   [clojure.data.json :as json]
+   [clojure.tools.logging :as log]
+   [integrant.core :as ig])
+  (:import
+   [io.undertow.websockets.core WebSockets WebSocketChannel]
+   [java.net URI]
+   [java.net.http HttpClient WebSocket$Builder WebSocket$Listener]
+   [java.time Instant ZoneId]
+   [java.time.format DateTimeFormatter]
+   [java.util Locale]
+   [java.util.concurrent CompletableFuture]))
+
+(defn- close-quietly [^WebSocketChannel ch]
+  (when (and ch (.isOpen ch))
+    (try (.close ch) (catch Exception _))))
+
+(defn- close-upstream-quietly [^java.net.http.WebSocket ws]
+  (when ws
+    (try (.sendClose ws java.net.http.WebSocket/NORMAL_CLOSURE "") (catch Exception _))))
+
+(defn- connect-upstream
+  "Open a Java HttpClient WebSocket to btcdata, transform each text frame
+   with xf, and send the result to the browser channel."
+  [^String btcdata-ws-url ^WebSocketChannel browser-ch xf]
+  (let [client   (HttpClient/newHttpClient)
+        listener (reify java.net.http.WebSocket$Listener
+                   (onOpen [_ ws]
+                     (.request ws 1))
+                   (onText [_ ws data last?]
+                     (let [text (str data)]
+                       (try
+                         (when (and (.isOpen browser-ch) (seq text))
+                           (WebSockets/sendTextBlocking (xf text) browser-ch))
+                         (catch Exception e
+                           (log/debug e "Error forwarding to browser")
+                           (close-upstream-quietly ws))))
+                     (.request ws 1)
+                     (CompletableFuture/completedFuture nil))
+                   (onClose [_ _ws status-code _reason]
+                     (log/debug "Upstream closed" status-code)
+                     (close-quietly browser-ch))
+                   (onError [_ _ws error]
+                     (log/debug error "Upstream error")
+                     (close-quietly browser-ch)))]
+    (-> (.newWebSocketBuilder client)
+        ^WebSocket$Builder identity
+        (.buildAsync (URI. btcdata-ws-url) listener)
+        (.join))))
+
+(defn- ws-handler [btcdata-ws-url xf _req]
+  (let [upstream-atom (atom nil)]
+    {:undertow/websocket
+     {:on-open
+      (fn [{:keys [^WebSocketChannel channel]}]
+        (log/info "Browser connected, proxying to" btcdata-ws-url)
+        (reset! upstream-atom (connect-upstream btcdata-ws-url channel xf)))
+      :on-close-message
+      (fn [_]
+        (log/debug "Browser closed")
+        (close-upstream-quietly @upstream-atom))}}))
+
+;; --- Price rendering ---
+
+(def ^:private ts-fmt (DateTimeFormatter/ofPattern "dd-MM HH:mm:ss"))
+(def ^:private da-locale (Locale. "da" "DK"))
+
+(defn- da-fmt [fmt val]
+  (String/format da-locale fmt (into-array Object [val])))
+
+(defn- price-json->html [text]
+  (let [{:strs [price prev_price recorded_at
+                price_eur price_dkk]} (json/read-str text)
+        p     (double (bigdec price))
+        pp    (when prev_price (double (bigdec prev_price)))
+        color (cond
+                (nil? pp) "text-gray-900"
+                (> p pp)  "text-green-600"
+                (< p pp)  "text-red-600"
+                :else     "text-gray-900")
+        ts    (.format (.atZone (Instant/parse recorded_at) (ZoneId/systemDefault)) ts-fmt)]
+    (str "<div id=\"price-display\">"
+         "<div class=\"bg-white rounded-2xl shadow-sm border border-gray-200 p-6\">"
+         "<div class=\"text-center\">"
+         "<p class=\"text-4xl font-bold " color "\">$" (da-fmt "%,.2f" p) "</p>"
+         (when price_eur
+           (let [p-eur (double (bigdec price_eur))
+                 p-dkk (double (bigdec price_dkk))
+                 eur   (/ p-eur p)
+                 dkk   (/ p-dkk p)]
+             (str "<div class=\"flex justify-center gap-4 mt-3\">"
+                  "<span class=\"text-2xl font-bold text-gray-600\">\u20AC" (da-fmt "%,.0f" p-eur) "</span>"
+                  "<span class=\"text-2xl font-bold text-gray-600\">" (da-fmt "%,.0f" p-dkk) " kr</span>"
+                  "</div>"
+                  "<div class=\"flex justify-center gap-4 mt-1\">"
+                  "<span class=\"text-xs text-gray-400\">EUR/USD " (da-fmt "%.4f" eur) "</span>"
+                  "<span class=\"text-xs text-gray-400\">DKK/USD " (da-fmt "%.4f" dkk) "</span>"
+                  "</div>")))
+         "<p class=\"text-xs text-gray-400 mt-2\">Updated " ts "</p>"
+         "</div></div></div>")))
+
+;; --- Strike rendering ---
+
+(def ^:private strike-pairs
+  [["BTC/USDT" "$"]
+   ["BTC/EUR"  "\u20AC"]
+   ["USDT/EUR" ""]
+   ["EUR/BTC"  ""]])
+
+(defn- format-strike-amount [prefix amount]
+  (if amount
+    (let [v (double (bigdec amount))]
+      (case prefix
+        "$"      (str prefix (da-fmt "%,.2f" v))
+        "\u20AC" (str prefix (da-fmt "%,.2f" v))
+        amount))
+    "\u2014"))
+
+(defn- strike-json->html [text]
+  (let [rates (json/read-str text)
+        sats  (get rates "quote-sats")]
+    (str "<div id=\"strike-display\">"
+         "<div class=\"rounded-2xl shadow-sm border border-gray-200 p-6\" style=\"background:#f3f4f6;\">"
+         (if sats
+           (str "<p class=\"text-center text-2xl font-bold mb-3\" style=\"color:#1e3a5f;\">"
+                (da-fmt "%,d" sats) " <span style=\"color:#1e3a5f;\">sats</span></p>")
+           "")
+         "<div style=\"display:grid;grid-template-columns:1fr;row-gap:0.25rem;\">"
+         (apply str
+           (for [[pair prefix] strike-pairs
+                 :let [amount (get rates pair)]]
+             (str "<div style=\"display:flex;justify-content:space-between;align-items:center;padding:0.25rem 0;\">"
+                  "<span class=\"text-sm text-gray-500\">" pair "</span>"
+                  "<span class=\"text-sm font-bold text-gray-900\">"
+                  (format-strike-amount prefix amount)
+                  "</span></div>")))
+         "</div></div></div>")))
+
+;; --- Routes ---
+
+(defn- ws-proxy-routes [{:keys [btcdata-url]}]
+  (let [ws-base (str (.replaceFirst ^String btcdata-url "^http" "ws"))]
+    [["/ws/price"
+      {:get        (fn [req] (ws-handler (str ws-base "/api/price/ws") price-json->html req))
+       :no-doc     true
+       :middleware []}]
+     ["/ws/strike"
+      {:get        (fn [req] (ws-handler (str ws-base "/api/strike/ws") strike-json->html req))
+       :no-doc     true
+       :middleware []}]]))
+
+(derive :reitit.routes/ws-proxy :reitit/routes)
+
+(defmethod ig/init-key :reitit.routes/ws-proxy
+  [_ {:keys [base-path]
+      :or   {base-path ""}
+      :as   opts}]
+  [base-path {} (ws-proxy-routes opts)])

src/clj/pmagnus/btcprice/ws/binance.clj

@@ -1,85 +0,0 @@
-(ns pmagnus.btcprice.ws.binance
-  (:require
-   [clojure.data.json :as json]
-   [clojure.tools.logging :as log]
-   [integrant.core :as ig])
-  (:import
-   [java.net URI]
-   [java.net.http HttpClient WebSocket WebSocket$Listener]
-   [java.util.concurrent CompletableFuture CompletionStage]))
-
-(defn- save-price! [query-fn price]
-  (try
-    (query-fn :insert-binance-price! {:price price})
-    (catch Exception e
-      (log/error e "Failed to save BTC price"))))
-
-(defn- connect!
-  "Opens a WebSocket to Binance trade stream and returns the WebSocket instance.
-   `state` is an atom with keys :running?, :last-write, :buffer."
-  [uri query-fn state]
-  (let [client   (HttpClient/newHttpClient)
-        listener (reify WebSocket$Listener
-                   (onOpen [_ ws]
-                     (log/info "Binance WebSocket connected")
-                     (.request ws 1))
-
-                   (onText [_ ws data last?]
-                     (let [buf (:buffer @state)]
-                       (.append buf data)
-                       (when last?
-                         (let [text (str buf)]
-                           (.setLength buf 0)
-                           (try
-                             (let [msg   (json/read-str text :key-fn keyword)
-                                   price (some-> (:p msg) bigdec)]
-                               (when price
-                                 (let [now (System/currentTimeMillis)]
-                                   (when (> (- now (:last-write @state)) 5000)
-                                     (swap! state assoc :last-write now)
-                                     (log/info "BTC price:" (str price))
-                                     (save-price! query-fn price)))))
-                             (catch Exception e
-                               (log/error e "Failed to parse Binance message")))))
-                       (let [^CompletionStage cf (CompletableFuture/completedFuture nil)]
-                         (.request ws 1)
-                         cf)))
-
-                   (onClose [_ _ws code reason]
-                     (log/warn "Binance WebSocket closed:" code reason)
-                     (when (:running? @state)
-                       (future
-                         (Thread/sleep 3000)
-                         (when (:running? @state)
-                           (log/info "Reconnecting to Binance...")
-                           (try
-                             (let [ws (connect! uri query-fn state)]
-                               (swap! state assoc :ws ws))
-                             (catch Exception e
-                               (log/error e "Binance reconnect failed")))))))
-
-                   (onError [_ _ws error]
-                     (log/error error "Binance WebSocket error")))]
-    (-> (.newWebSocketBuilder client)
-        (.buildAsync (URI. uri) listener)
-        (.join))))
-
-(defmethod ig/init-key :ws/binance
-  [_ {:keys [query-fn uri]}]
-  (log/info "Starting Binance WebSocket listener:" uri)
-  (let [state (atom {:running?   true
-                     :last-write 0
-                     :buffer     (StringBuilder.)
-                     :ws         nil})
-        ws    (connect! uri query-fn state)]
-    (swap! state assoc :ws ws)
-    state))
-
-(defmethod ig/halt-key! :ws/binance
-  [_ state]
-  (log/info "Stopping Binance WebSocket listener")
-  (swap! state assoc :running? false)
-  (when-let [ws (:ws @state)]
-    (try
-      (.sendClose ws WebSocket/NORMAL_CLOSURE "shutting down")
-      (catch Exception _))))