fix(ui): keep streaming bash output pinned (#556)

## Summary
- notify the existing virtual follow-list path after streaming bash ANSI
output updates
- restore the inner bash output scroll immediately after direct pre
updates
- apply the same coalesced notification pattern to final ANSI output

## Validation
- npm run typecheck --workspace @codenomad/ui

Author: shantur

packages/ui/src/components/tool-call/renderers/bash.tsx

@@ -10,17 +10,36 @@ import { getBashToolSearchText } from "../search-text"
 function RunningBashOutput(props: {
   content: Accessor<string>
   scrollHelpers?: ToolScrollHelpers
+  onContentRendered?: () => void
 }) {
   let preRef: HTMLPreElement | undefined
+  let pendingRenderNotificationFrame: number | null = null
   const updater = createStableAnsiStreamUpdater()
 
+  const notifyContentRendered = () => {
+    if (!props.onContentRendered || typeof requestAnimationFrame !== "function") return
+    if (pendingRenderNotificationFrame !== null) {
+      cancelAnimationFrame(pendingRenderNotificationFrame)
+    }
+    pendingRenderNotificationFrame = requestAnimationFrame(() => {
+      pendingRenderNotificationFrame = null
+      props.onContentRendered?.()
+    })
+  }
+
   createEffect(() => {
     const element = preRef
     if (!element) return
     updater.update(element, props.content())
+    props.scrollHelpers?.restoreAfterRender()
+    notifyContentRendered()
   })
 
   onCleanup(() => {
+    if (pendingRenderNotificationFrame !== null) {
+      cancelAnimationFrame(pendingRenderNotificationFrame)
+      pendingRenderNotificationFrame = null
+    }
     preRef = undefined
     updater.reset()
   })
@@ -37,10 +56,49 @@ function RunningBashOutput(props: {
   )
 }
 
+function FinalAnsiOutput(props: {
+  html: string
+  scrollHelpers?: ToolScrollHelpers
+  onContentRendered?: () => void
+}) {
+  let pendingRenderNotificationFrame: number | null = null
+
+  const notifyContentRendered = () => {
+    if (!props.onContentRendered || typeof requestAnimationFrame !== "function") return
+    if (pendingRenderNotificationFrame !== null) {
+      cancelAnimationFrame(pendingRenderNotificationFrame)
+    }
+    pendingRenderNotificationFrame = requestAnimationFrame(() => {
+      pendingRenderNotificationFrame = null
+      props.onContentRendered?.()
+    })
+  }
+
+  createEffect(() => {
+    props.html
+    props.scrollHelpers?.restoreAfterRender()
+    notifyContentRendered()
+  })
+
+  onCleanup(() => {
+    if (pendingRenderNotificationFrame !== null) {
+      cancelAnimationFrame(pendingRenderNotificationFrame)
+      pendingRenderNotificationFrame = null
+    }
+  })
+
+  return (
+    <div class="message-text tool-call-markdown" ref={props.scrollHelpers?.registerContainer}>
+      <pre class="tool-call-content tool-call-ansi" dir="auto" innerHTML={props.html} />
+    </div>
+  )
+}
+
 function BashToolBody(props: {
   toolState: Accessor<ToolState | undefined>
   renderMarkdown: (options: { content: string }) => ReturnType<ToolRenderer["renderBody"]>
   scrollHelpers?: ToolScrollHelpers
+  onContentRendered?: () => void
 }) {
   const state = createMemo(() => props.toolState())
 
@@ -91,14 +149,12 @@ function BashToolBody(props: {
         fallback={
           <Show when={finalAnsiHtml()} fallback={finalMarkdown() ? props.renderMarkdown({ content: finalMarkdown()! as string }) : null}>
             {(html) => (
-              <div class="message-text tool-call-markdown" ref={props.scrollHelpers?.registerContainer}>
-                <pre class="tool-call-content tool-call-ansi" dir="auto" innerHTML={html()} />
-              </div>
+              <FinalAnsiOutput html={html()} scrollHelpers={props.scrollHelpers} onContentRendered={props.onContentRendered} />
             )}
           </Show>
         }
       >
-        <RunningBashOutput content={joinedContent} scrollHelpers={props.scrollHelpers} />
+        <RunningBashOutput content={joinedContent} scrollHelpers={props.scrollHelpers} onContentRendered={props.onContentRendered} />
       </Show>
     </Show>
   )
@@ -124,7 +180,7 @@ export const bashRenderer: ToolRenderer = {
     const timeoutLabel = `${timeout}ms`
     return `${baseTitle} · ${tGlobal("toolCall.renderer.bash.title.timeout", { timeout: timeoutLabel })}`
   },
-  renderBody({ toolState, renderMarkdown, scrollHelpers }) {
-    return <BashToolBody toolState={toolState} renderMarkdown={renderMarkdown as any} scrollHelpers={scrollHelpers} />
+  renderBody({ toolState, renderMarkdown, scrollHelpers, onContentRendered }) {
+    return <BashToolBody toolState={toolState} renderMarkdown={renderMarkdown as any} scrollHelpers={scrollHelpers} onContentRendered={onContentRendered} />
   },
 }