Control UI: preserve chat scroll when scrolled up

Closes #217

CHANGELOG.md

@@ -7,6 +7,7 @@
 - Memory: allow custom OpenAI-compatible embedding endpoints for memory search (remote baseUrl/apiKey/headers). (#819 — thanks @mukhtharcm)
 
 ### Fixes
+- Control UI: keep chat scroll position unless user is near the bottom. (#217 — thanks @thewilloftheshadow)
 - Fallback: treat credential validation failures ("no credentials found", "no API key found") as auth errors that trigger model fallback. (#822 — thanks @sebslight)
 - Telegram: preserve forum topic thread ids, including General topic replies. (#727 — thanks @thewilloftheshadow)
 - Telegram: persist polling update offsets across restarts to avoid duplicate updates. (#739 — thanks @thewilloftheshadow)

ui/src/ui/app-render.ts

@@ -494,13 +494,14 @@ export function renderApp(state: AppViewState) {
                   ...state.settings,
                   useNewChatLayout: !state.settings.useNewChatLayout,
                 }),
-	              onDraftChange: (next) => (state.chatMessage = next),
-	              onSend: () => state.handleSendChat(),
-	              canAbort: Boolean(state.chatRunId),
-	              onAbort: () => void state.handleAbortChat(),
-	              onQueueRemove: (id) => state.removeQueuedMessage(id),
-	              onNewSession: () =>
-	                state.handleSendChat("/new", { restoreDraft: true }),
+              onChatScroll: (event) => state.handleChatScroll(event),
+              onDraftChange: (next) => (state.chatMessage = next),
+              onSend: () => state.handleSendChat(),
+              canAbort: Boolean(state.chatRunId),
+              onAbort: () => void state.handleAbortChat(),
+              onQueueRemove: (id) => state.removeQueuedMessage(id),
+              onNewSession: () =>
+                state.handleSendChat("/new", { restoreDraft: true }),
               // Sidebar props for tool output viewing
               sidebarOpen: state.sidebarOpen,
               sidebarContent: state.sidebarContent,

ui/src/ui/app.ts

@@ -400,6 +400,7 @@ export class ClawdbotApp extends LitElement {
   private chatScrollFrame: number | null = null;
   private chatScrollTimeout: number | null = null;
   private chatHasAutoScrolled = false;
+  private chatUserNearBottom = true;
   private nodesPollInterval: number | null = null;
   private logsPollInterval: number | null = null;
   private logsScrollFrame: number | null = null;
@@ -525,10 +526,12 @@ export class ClawdbotApp extends LitElement {
         if (!target) return;
         const distanceFromBottom =
           target.scrollHeight - target.scrollTop - target.clientHeight;
-        const shouldStick = force || distanceFromBottom < 200;
+        const shouldStick =
+          force || this.chatUserNearBottom || distanceFromBottom < 200;
         if (!shouldStick) return;
         if (force) this.chatHasAutoScrolled = true;
         target.scrollTop = target.scrollHeight;
+        this.chatUserNearBottom = true;
         const retryDelay = force ? 150 : 120;
         this.chatScrollTimeout = window.setTimeout(() => {
           this.chatScrollTimeout = null;
@@ -536,8 +539,11 @@ export class ClawdbotApp extends LitElement {
           if (!latest) return;
           const latestDistanceFromBottom =
             latest.scrollHeight - latest.scrollTop - latest.clientHeight;
-          if (!force && latestDistanceFromBottom >= 250) return;
+          const shouldStickRetry =
+            force || this.chatUserNearBottom || latestDistanceFromBottom < 200;
+          if (!shouldStickRetry) return;
           latest.scrollTop = latest.scrollHeight;
+          this.chatUserNearBottom = true;
         }, retryDelay);
       });
     });
@@ -600,6 +606,14 @@ export class ClawdbotApp extends LitElement {
     });
   }
 
+  handleChatScroll(event: Event) {
+    const container = event.currentTarget as HTMLElement | null;
+    if (!container) return;
+    const distanceFromBottom =
+      container.scrollHeight - container.scrollTop - container.clientHeight;
+    this.chatUserNearBottom = distanceFromBottom < 200;
+  }
+
   handleLogsScroll(event: Event) {
     const container = event.currentTarget as HTMLElement | null;
     if (!container) return;
@@ -630,6 +644,7 @@ export class ClawdbotApp extends LitElement {
 
   resetChatScroll() {
     this.chatHasAutoScrolled = false;
+    this.chatUserNearBottom = true;
   }
 
   toggleToolOutput(id: string, expanded: boolean) {

ui/src/ui/views/chat.ts

@@ -59,6 +59,7 @@ export type ChatProps = {
   onOpenSidebar?: (content: string) => void;
   onCloseSidebar?: () => void;
   onSplitRatioChange?: (ratio: number) => void;
+  onChatScroll?: (event: Event) => void;
 };
 
 export function renderChat(props: ChatProps) {
@@ -109,7 +110,12 @@ export function renderChat(props: ChatProps) {
           class="chat-main"
           style="flex: ${sidebarOpen ? `0 0 ${splitRatio * 100}%` : "1 1 100%"}"
         >
-          <div class="chat-thread" role="log" aria-live="polite">
+          <div
+            class="chat-thread"
+            role="log"
+            aria-live="polite"
+            @scroll=${props.onChatScroll}
+          >
             ${props.loading
               ? html`<div class="muted">Loading chat…</div>`
               : nothing}