Centralize tool call scroll helpers

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

@@ -9,7 +9,14 @@ import type { DiffViewMode } from "../stores/preferences"
 import { sendPermissionResponse } from "../stores/instances"
 import type { TextPart, RenderCache } from "../types/message"
 import { resolveToolRenderer } from "./tool-call/renderers"
-import type { DiffPayload, DiffRenderOptions, MarkdownRenderOptions, ToolCallPart, ToolRendererContext } from "./tool-call/types"
+import type {
+  DiffPayload,
+  DiffRenderOptions,
+  MarkdownRenderOptions,
+  ToolCallPart,
+  ToolRendererContext,
+  ToolScrollHelpers,
+} from "./tool-call/types"
 import { getRelativePath, getToolIcon, getToolName, isToolStateCompleted, isToolStateError, isToolStateRunning } from "./tool-call/utils"
 import { getLogger } from "../lib/logger"
 
@@ -419,7 +426,20 @@ export default function ToolCall(props: ToolCallProps) {
     persistScrollSnapshot(event.currentTarget)
   }
 
+  const scrollHelpers: ToolScrollHelpers = {
+    registerContainer: (element, options) => {
+      if (options?.disableTracking) return
+      initializeScrollContainer(element)
+    },
+    handleScroll: handleScrollEvent,
+    renderSentinel: (options) => {
+      if (options?.disableTracking) return null
+      return <div ref={setBottomSentinel} aria-hidden="true" class="tool-call-scroll-sentinel" style={{ height: "1px" }} />
+    },
+  }
+
   createEffect(() => {
+
     const container = scrollContainer()
     if (!container) return
 
@@ -565,11 +585,8 @@ export default function ToolCall(props: ToolCallProps) {
     return (
       <div
         class="message-text tool-call-markdown tool-call-markdown-large tool-call-diff-shell"
-        ref={(element) => {
-          if (options?.disableScrollTracking) return
-          initializeScrollContainer(element)
-        }}
-        onScroll={options?.disableScrollTracking ? undefined : handleScrollEvent}
+        ref={(element) => scrollHelpers.registerContainer(element, { disableTracking: options?.disableScrollTracking })}
+        onScroll={options?.disableScrollTracking ? undefined : scrollHelpers.handleScroll}
       >
         <div class="tool-call-diff-toolbar" role="group" aria-label="Diff view mode">
           <span class="tool-call-diff-toolbar-label">{toolbarLabel}</span>
@@ -601,9 +618,7 @@ export default function ToolCall(props: ToolCallProps) {
           cacheEntryParams={cacheHandle.params()}
           onRendered={handleDiffRendered}
         />
-        <Show when={!options?.disableScrollTracking}>
-          <div ref={setBottomSentinel} aria-hidden="true" class="tool-call-scroll-sentinel" style={{ height: "1px" }} />
-        </Show>
+        {scrollHelpers.renderSentinel({ disableTracking: options?.disableScrollTracking })}
       </div>
     )
   }
@@ -630,14 +645,14 @@ export default function ToolCall(props: ToolCallProps) {
     }
 
     return (
-      <div class={messageClass} ref={(element) => initializeScrollContainer(element)} onScroll={handleScrollEvent}>
+      <div class={messageClass} ref={(element) => scrollHelpers.registerContainer(element)} onScroll={scrollHelpers.handleScroll}>
         <Markdown
           part={markdownPart}
           isDark={isDark()}
           disableHighlight={disableHighlight}
           onRendered={handleMarkdownRendered}
         />
-        <div ref={setBottomSentinel} aria-hidden="true" class="tool-call-scroll-sentinel" style={{ height: "1px" }} />
+        {scrollHelpers.renderSentinel()}
       </div>
     )
   }
@@ -654,6 +669,7 @@ export default function ToolCall(props: ToolCallProps) {
     partVersion: partVersionAccessor,
     renderMarkdown: renderMarkdownContent,
     renderDiff: renderDiffContent,
+    scrollHelpers,
   }
 
   let previousPartVersion: number | undefined

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

@@ -40,7 +40,7 @@ export const taskRenderer: ToolRenderer = {
     }
     return base
   },
-  renderBody({ toolState, toolCall, messageVersion, partVersion }) {
+  renderBody({ toolState, toolCall, messageVersion, partVersion, scrollHelpers }) {
     const items = createMemo(() => {
       // Track the reactive change points so we only recompute when the part/message changes
       messageVersion?.()
@@ -63,7 +63,11 @@ export const taskRenderer: ToolRenderer = {
     if (items().length === 0) return null
 
     return (
-      <div class="message-text tool-call-markdown tool-call-task-container">
+      <div
+        class="message-text tool-call-markdown tool-call-task-container"
+        ref={(element) => scrollHelpers?.registerContainer(element)}
+        onScroll={scrollHelpers ? (event) => scrollHelpers.handleScroll(event as Event & { currentTarget: HTMLDivElement }) : undefined}
+      >
         <div class="tool-call-task-summary">
           <For each={items()}>
             {(item) => {
@@ -78,7 +82,9 @@ export const taskRenderer: ToolRenderer = {
             }}
           </For>
         </div>
+        {scrollHelpers?.renderSentinel?.()}
       </div>
     )
   },
 }
+

packages/ui/src/components/tool-call/types.ts

@@ -21,6 +21,12 @@ export interface DiffRenderOptions {
   label?: string
 }
 
+export interface ToolScrollHelpers {
+  registerContainer(element: HTMLDivElement | null, options?: { disableTracking?: boolean }): void
+  handleScroll(event: Event & { currentTarget: HTMLDivElement }): void
+  renderSentinel(options?: { disableTracking?: boolean }): JSXElement | null
+}
+
 export interface ToolRendererContext {
   toolCall: Accessor<ToolCallPart>
   toolState: Accessor<ToolState | undefined>
@@ -29,6 +35,7 @@ export interface ToolRendererContext {
   partVersion?: Accessor<number | undefined>
   renderMarkdown(options: MarkdownRenderOptions): JSXElement | null
   renderDiff(payload: DiffPayload, options?: DiffRenderOptions): JSXElement | null
+  scrollHelpers?: ToolScrollHelpers
 }
 
 export interface ToolRenderer {