diff --git a/docs/javascript-architecture.md b/docs/javascript-architecture.md
index ff3320e..ca81126 100644
--- a/docs/javascript-architecture.md
+++ b/docs/javascript-architecture.md
@@ -1423,6 +1423,12 @@ If one of these breaks, inspect this controller first.
 - `tickClockHelper(...)`
 - `handleSessionTimerTickHelper(...)`
 
+Background rendering rule:
+- `Timing`, `Dashboard`, and `Overlay` may rerender for live timing updates where explicitly allowed.
+- decoder WebSocket `open`, `close`, and `error` events must not rerender `Settings`; they update the global connection badge instead.
+- `app.js#renderViewFromBackground()` skips the one-time backend/voice refresh while a Settings control has focus or has changed.
+- explicit Settings actions such as Save, Start AMMC, Stop AMMC, or Refresh may render after completing because the submitted values are already captured.
+
 #### AMMC/backend control
 - `loadAmmcConfigFromBackendHelper(...)`
 - `saveAmmcConfigToBackendHelper(...)`
@@ -2261,6 +2267,23 @@ Mitigation:
 - treat backend hydration and local dirty flags as runtime concerns
 - inspect `src/runtime_services.js` together with the affected save path
 
+## 17.7 Settings forms replaced by decoder reconnect
+
+Observed failure:
+- decoder IP/port fields and checkboxes reset while the operator was typing
+- the operator had to enter and save values before the next refresh
+
+Pattern:
+- an unreachable or unstable WebSocket triggers `error`, `close`, reconnect after two seconds, and `open/error` again
+- each lifecycle event previously called full `renderView()` while `Settings` was active
+- initial backend hydration or `voiceschanged` could also replace a newly focused form
+
+Mitigation:
+- never include `settings` in decoder lifecycle rerender targets in `src/decoder_runtime.js`
+- use `renderViewFromBackground()` for asynchronous app/bootstrap updates
+- mark Settings as draft-active on `focusin`, `input`, and `change`
+- keep a regression assertion in `tests/decoder_runtime.test.js` that `open/error/close` does not render Settings
+
 ## 18. Automated Regression Tests
 
 Run:
@@ -2313,6 +2336,12 @@ npm test
 - dirty-state protection when newer local edits occur during a request
 - failed-sync behavior without false version advancement
 
+`tests/decoder_runtime.test.js` covers:
+- split and pit roles never incrementing normal laps
+- pit-entry attribution surviving an endurance driver/transponder change
+- one WebSocket per enabled decoder role
+- decoder lifecycle events not rerendering and replacing the Settings form
+
 `tests/audio_runtime.test.js` covers:
 - explicit and language-based speech voice selection
 - practice-specific versus race-specific start/finish phrases
diff --git a/src/app.js b/src/app.js
index b3214ea..b7fa95f 100644
--- a/src/app.js
+++ b/src/app.js
@@ -2540,6 +2540,7 @@ let lastOverlayBestLapByKey = {};
 let activeModalEscapeHandler = null;
 let settingsStorageNotice = "";
 let settingsStorageNoticeIsError = false;
+let settingsDraftActive = false;
 const backend = {
   available: false,
   lastSyncAt: null,
@@ -2568,9 +2569,12 @@ init();
 
 async function init() {
   document.body.classList.toggle("overlay-mode", overlayMode);
+  ["focusin", "input", "change"].forEach((eventName) => {
+    dom.view.addEventListener(eventName, markSettingsDraftActive);
+  });
   if ("speechSynthesis" in window) {
     window.speechSynthesis.addEventListener("voiceschanged", () => {
-      if (currentView === "settings") renderView();
+      if (currentView === "settings") renderViewFromBackground();
     });
   }
   seedDefaultData();
@@ -2587,7 +2591,7 @@ async function init() {
   Promise.allSettled([hydrateFromBackend(), loadAmmcConfigFromBackend()]).finally(() => {
     applyTheme();
     renderNav();
-    renderView();
+    renderViewFromBackground();
     setupLanguageControl();
     updateHeaderState();
     updateConnectionBadge();
@@ -2605,6 +2609,14 @@ async function init() {
   }
 }
 
+function markSettingsDraftActive(event) {
+  if (currentView !== "settings") return;
+  const target = event.target;
+  if (target instanceof HTMLInputElement || target instanceof HTMLSelectElement || target instanceof HTMLTextAreaElement) {
+    settingsDraftActive = true;
+  }
+}
+
 function seedDefaultData() {
   if (!state.classes.length) {
     state.classes.push(
@@ -3212,6 +3224,7 @@ function updateViewUrl(view, driverId = "", classId = "") {
 }
 
 function renderView() {
+  if (currentView === "settings") settingsDraftActive = false;
   clearModalEscapeHandler();
   const navMeta = NAV_ITEMS.find((x) => x.id === currentView);
   dom.pageTitle.textContent = navMeta ? t(navMeta.titleKey) : "";
@@ -3322,6 +3335,11 @@ function renderView() {
   updateHeaderState();
 }
 
+function renderViewFromBackground() {
+  if (currentView === "settings" && settingsDraftActive) return;
+  renderView();
+}
+
 function clearModalEscapeHandler() {
   if (activeModalEscapeHandler) {
     document.removeEventListener("keydown", activeModalEscapeHandler);
diff --git a/src/decoder_runtime.js b/src/decoder_runtime.js
index 0dac3d2..23657a2 100644
--- a/src/decoder_runtime.js
+++ b/src/decoder_runtime.js
@@ -162,7 +162,7 @@ function connectDecoderRole(role, deps) {
     state.decoder[lastErrorKey] = "";
     saveState();
     updateConnectionBadge();
-    if (["timing", "settings", "overlay"].includes(getCurrentView())) {
+    if (["timing", "overlay"].includes(getCurrentView())) {
       renderView();
     }
   };
@@ -207,7 +207,7 @@ function connectDecoderRole(role, deps) {
       }, 2000));
     }
 
-    if (["timing", "settings", "overlay"].includes(getCurrentView())) {
+    if (["timing", "overlay"].includes(getCurrentView())) {
       renderView();
     }
   };
@@ -216,7 +216,7 @@ function connectDecoderRole(role, deps) {
     state.decoder[lastErrorKey] = t("error.decoder_connection");
     saveState();
     updateConnectionBadge();
-    if (["timing", "settings", "overlay"].includes(getCurrentView())) {
+    if (["timing", "overlay"].includes(getCurrentView())) {
       renderView();
     }
   };
diff --git a/tests/decoder_runtime.test.js b/tests/decoder_runtime.test.js
index 7f75d9c..a05e3e8 100644
--- a/tests/decoder_runtime.test.js
+++ b/tests/decoder_runtime.test.js
@@ -106,6 +106,7 @@ test("connect decoder opens one websocket per enabled role", () => {
     const clients = {};
     const timers = {};
     let disconnected = 0;
+    let renderCount = 0;
     const state = {
       settings: {
         wsUrl: "ws://server:9000",
@@ -125,8 +126,8 @@ test("connect decoder opens one websocket per enabled role", () => {
       setWsClient: (role, client) => { clients[role] = client; },
       getReconnectTimer: (role) => timers[role] || null,
       setReconnectTimer: (role, timer) => { timers[role] = timer; },
-      getCurrentView: () => "dashboard",
-      renderView: () => {},
+      getCurrentView: () => "settings",
+      renderView: () => { renderCount += 1; },
       updateConnectionBadge: () => {},
       processDecoderMessage: () => {},
       disconnectDecoder: () => { disconnected += 1; },
@@ -138,6 +139,10 @@ test("connect decoder opens one websocket per enabled role", () => {
       pit_entry: "ws://server:9002",
       pit_exit: "ws://server:9003",
     });
+    clients.main.onopen();
+    clients.main.onerror();
+    clients.main.onclose();
+    assert.equal(renderCount, 0);
   } finally {
     globalThis.WebSocket = OriginalWebSocket;
   }