diff --git a/packages/kilo-vscode/tests/unit/task-tool-state.test.ts b/packages/kilo-vscode/tests/unit/task-tool-state.test.ts
new file mode 100644
index 00000000000..18aba7ca79e
--- /dev/null
+++ b/packages/kilo-vscode/tests/unit/task-tool-state.test.ts
@@ -0,0 +1,24 @@
+import { describe, expect, it } from "bun:test"
+import { taskBackground } from "../../webview-ui/src/components/chat/task-tool-state"
+
+describe("taskBackground", () => {
+  it("reads the background flag from the streamed input", () => {
+    expect(taskBackground({ background: true }, undefined, undefined)).toBe(true)
+  })
+
+  it("reads the background flag from part or state metadata", () => {
+    expect(taskBackground({}, { background: true }, undefined)).toBe(true)
+    expect(taskBackground(undefined, undefined, { background: true })).toBe(true)
+  })
+
+  it("prefers part metadata over state metadata", () => {
+    expect(taskBackground({}, { background: false }, { background: true })).toBe(false)
+    expect(taskBackground({}, { background: true }, { background: false })).toBe(true)
+  })
+
+  it("is false without an explicit true flag", () => {
+    expect(taskBackground({}, {}, {})).toBe(false)
+    expect(taskBackground(undefined, undefined, undefined)).toBe(false)
+    expect(taskBackground({ background: "yes" }, {}, {})).toBe(false)
+  })
+})
diff --git a/packages/kilo-vscode/webview-ui/src/components/chat/TaskToolExpanded.tsx b/packages/kilo-vscode/webview-ui/src/components/chat/TaskToolExpanded.tsx
index 86552bb7b62..d0051227599 100644
--- a/packages/kilo-vscode/webview-ui/src/components/chat/TaskToolExpanded.tsx
+++ b/packages/kilo-vscode/webview-ui/src/components/chat/TaskToolExpanded.tsx
@@ -24,7 +24,14 @@ import { useWorktreeMode } from "../../context/worktree-mode"
 import { childID, latestTaskPart } from "../../context/session-utils"
 import { useConfig } from "../../context/config"
 import { openSubagent } from "./open-subagent"
-import { showChildPromotion, taskAvatarStatus, taskResult, taskRunning, taskVisible } from "./task-tool-state"
+import {
+  showChildPromotion,
+  taskAvatarStatus,
+  taskBackground,
+  taskResult,
+  taskRunning,
+  taskVisible,
+} from "./task-tool-state"
 
 const TaskToolRenderer: Component<ToolProps> = (props) => {
   const i18n = useI18n()
@@ -63,12 +70,7 @@ const TaskToolRenderer: Component<ToolProps> = (props) => {
   // "Starting..." status, which would flicker the transcript as the child runs.
   // The input carries `background` from the first part update; promoted tasks
   // only gain the state metadata flag later.
-  const backgroundTask = createMemo(
-    () =>
-      props.input.background === true ||
-      ((props.partMetadata as Record<string, unknown> | undefined)?.background ??
-        (props.metadata as Record<string, unknown> | undefined)?.background) === true,
-  )
+  const backgroundTask = createMemo(() => taskBackground(props.input, props.partMetadata, props.metadata))
   const avatar = createMemo(() => {
     const id = childSessionId()
     return taskAvatarStatus(id, props.status, session.allStatusMap())
@@ -115,11 +117,11 @@ const TaskToolRenderer: Component<ToolProps> = (props) => {
   }
   createEffect(() => {
     if (touched()) return
-    if (backgroundTask()) {
-      setOpen(false)
+    if (auto()) {
+      setOpen(true)
       return
     }
-    if (props.status === "running") setOpen(true)
+    if (backgroundTask()) setOpen(false)
   })
 
   let synced: string | undefined
diff --git a/packages/kilo-vscode/webview-ui/src/components/chat/task-tool-state.ts b/packages/kilo-vscode/webview-ui/src/components/chat/task-tool-state.ts
index 7014587d2fa..6543ae4c5c0 100644
--- a/packages/kilo-vscode/webview-ui/src/components/chat/task-tool-state.ts
+++ b/packages/kilo-vscode/webview-ui/src/components/chat/task-tool-state.ts
@@ -19,6 +19,19 @@ export function taskAvatarStatus(
   return undefined
 }
 
+/**
+ * True when a Task part is a background child. The streamed input carries the
+ * flag from the first part update; part metadata wins over state metadata.
+ */
+export function taskBackground(
+  input: Record<string, unknown> | undefined,
+  part: Record<string, unknown> | undefined,
+  state: Record<string, unknown> | undefined,
+) {
+  if (input?.background === true) return true
+  return (part?.background ?? state?.background) === true
+}
+
 export function childForeground(
   id: string | undefined,
   part: Record<string, unknown> | undefined,