Live log view over WebSocket, full log, scroll pinned to bottom

frontend/src/components/Header.vue

@@ -306,9 +306,8 @@
 
             <div class="diag-log-header">
               <span class="diag-label">Application log</span>
-              <button class="diag-refresh-btn" @click="refreshLog">Refresh</button>
             </div>
-            <pre class="diag-log">{{ appLog }}</pre>
+            <pre ref="logEl" class="diag-log" @scroll="onLogScroll">{{ appLog }}</pre>
           </section>
         </div>
       </div>
@@ -317,11 +316,11 @@
 </template>
 
 <script setup lang="ts">
-import { ref, watch, computed, onMounted, onUnmounted } from "vue"
+import { ref, watch, computed, onMounted, onUnmounted, nextTick } from "vue"
 import { useRouter, useRoute } from "vue-router"
 import { navAttrs } from "../composables/useKeyboardNavigation"
 import logoUrl from "../assets/mediahive.webp"
-import { replaceRoots, pickFolderAndAddRoot, fetchPlayers, getLog } from "../api"
+import { replaceRoots, pickFolderAndAddRoot, fetchPlayers } from "../api"
 import type { PlayerInfo } from "../api"
 import HexKeyboard from "./HexKeyboard.vue"
 import {
@@ -425,15 +424,38 @@ async function refreshPlayers() {
 }
 
 const appLog = ref("")
-let logFetched = false
+const logEl = ref<HTMLElement | null>(null)
+let logSocket: WebSocket | null = null
+let pinnedToBottom = true
 
-async function refreshLog() {
-  try {
-    appLog.value = await getLog()
-  } catch (e) {
-    console.error("Failed to fetch log:", e)
-    appLog.value = "Failed to load log."
+function onLogScroll() {
+  const el = logEl.value
+  if (!el) return
+  pinnedToBottom = el.scrollHeight - el.scrollTop - el.clientHeight < 48
+}
+
+function connectLogSocket() {
+  if (logSocket) return
+  const proto = location.protocol === "https:" ? "wss" : "ws"
+  const ws = new WebSocket(`${proto}://${location.host}/api/log/ws`)
+  logSocket = ws
+  pinnedToBottom = true
+  ws.onmessage = async (ev) => {
+    appLog.value = String(ev.data)
+    await nextTick()
+    const el = logEl.value
+    if (el && pinnedToBottom) el.scrollTop = el.scrollHeight
   }
+  ws.onclose = () => {
+    if (logSocket === ws) logSocket = null
+    if (showSettings.value) setTimeout(connectLogSocket, 3000)
+  }
+}
+
+function disconnectLogSocket() {
+  const ws = logSocket
+  logSocket = null
+  ws?.close()
 }
 
 async function removeRoot(rootId: string) {
@@ -465,10 +487,9 @@ async function addRoot() {
 watch(showSettings, (visible) => {
   if (visible) {
     void refreshPlayers()
-    if (!logFetched) {
-      logFetched = true
-      void refreshLog()
-    }
+    connectLogSocket()
+  } else {
+    disconnectLogSocket()
   }
 })
 
@@ -582,6 +603,7 @@ onMounted(() => {
 onUnmounted(() => {
   window.removeEventListener("keydown", handleKeydown)
   window.removeEventListener("mediahive:gamepad-action", onGamepadAction)
+  disconnectLogSocket()
 })
 </script>
 
@@ -912,21 +934,6 @@ onUnmounted(() => {
   margin-bottom: 6px;
 }
 
-.diag-refresh-btn {
-  padding: 4px 12px;
-  background: rgba(255, 255, 255, 0.08);
-  border: 1px solid rgba(255, 255, 255, 0.15);
-  border-radius: 6px;
-  color: var(--text-primary);
-  font-size: 0.8rem;
-  cursor: pointer;
-  transition: background 0.2s;
-}
-
-.diag-refresh-btn:hover {
-  background: rgba(255, 255, 255, 0.15);
-}
-
 .diag-log {
   font-family: ui-monospace, Menlo, Consolas, monospace;
   font-size: 0.75rem;