diff --git a/desktop/playwright.config.ts b/desktop/playwright.config.ts
index ff8a0e7703..8da7fdcd85 100644
--- a/desktop/playwright.config.ts
+++ b/desktop/playwright.config.ts
@@ -49,6 +49,7 @@ export default defineConfig({
         "**/profile-active-turn.spec.ts",
         "**/config-bridge-screenshots.spec.ts",
         "**/observer-feed-screenshots.spec.ts",
+        "**/transcript-tool-run-quality.smoke.spec.ts",
         "**/core-memory-screenshots.spec.ts",
         "**/activity-scope-label-screenshots.spec.ts",
         "**/welcome-agent-modal-screenshots.spec.ts",
diff --git a/desktop/src/features/agents/ui/AgentSessionToolItem/ToolItem.tsx b/desktop/src/features/agents/ui/AgentSessionToolItem/ToolItem.tsx
index e0f2ce9fbc..4913938cf3 100644
--- a/desktop/src/features/agents/ui/AgentSessionToolItem/ToolItem.tsx
+++ b/desktop/src/features/agents/ui/AgentSessionToolItem/ToolItem.tsx
@@ -29,11 +29,16 @@ export function ToolItem({
   agentPubkey,
   item,
   profiles,
+  expanded,
+  onExpansionChange,
 }: AgentTranscriptIdentityProps & {
   item: Extract<TranscriptItem, { type: "tool" }>;
   profiles?: UserProfileLookup;
+  expanded?: boolean;
+  onExpansionChange?: (expanded: boolean) => void;
 }) {
-  const [isExpanded, setIsExpanded] = React.useState(false);
+  const [localExpanded, setLocalExpanded] = React.useState(false);
+  const isExpanded = expanded ?? localExpanded;
   const hasArgs = Object.keys(item.args).length > 0;
   const hasResult = item.result.trim().length > 0;
   const canonicalToolName = item.buzzToolName ?? item.toolName;
@@ -52,9 +57,14 @@ export function ToolItem({
   const agentResolvedAvatarUrl = agentProfile?.avatarUrl ?? agentAvatarUrl;
   const handleToggle = React.useCallback(
     (event: React.SyntheticEvent<HTMLDetailsElement>) => {
-      setIsExpanded(event.currentTarget.open);
+      const nextExpanded = event.currentTarget.open;
+      if (onExpansionChange) {
+        onExpansionChange(nextExpanded);
+      } else {
+        setLocalExpanded(nextExpanded);
+      }
     },
-    [],
+    [onExpansionChange],
   );
 
   if (compactSummary.presentation === "message") {
diff --git a/desktop/src/features/agents/ui/AgentSessionTranscriptList.tsx b/desktop/src/features/agents/ui/AgentSessionTranscriptList.tsx
index 576cdbbf45..236edabeb7 100644
--- a/desktop/src/features/agents/ui/AgentSessionTranscriptList.tsx
+++ b/desktop/src/features/agents/ui/AgentSessionTranscriptList.tsx
@@ -533,7 +533,13 @@ function SameKindSummaryItem({
   // the group card never has to import this module back. Not memoized: the
   // group card calls it during render and never uses its identity as a
   // dependency, and memoizing would need this component as its own dep.
-  const renderChild = (child: TranscriptToolRunChildSegment) =>
+  const renderChild = (
+    child: TranscriptToolRunChildSegment,
+    expansion?: {
+      expanded: boolean;
+      onExpansionChange: (expanded: boolean) => void;
+    },
+  ) =>
     child.kind === "summary" ? (
       <SameKindSummaryItem
         agentAvatarUrl={agentAvatarUrl}
@@ -550,7 +556,9 @@ function SameKindSummaryItem({
         agentPubkey={agentPubkey}
         item={child.item}
         key={child.item.id}
+        onExpansionChange={expansion?.onExpansionChange}
         profiles={profiles}
+        expanded={expansion?.expanded}
       />
     );
 
@@ -948,17 +956,23 @@ const TranscriptItemView = React.memo(function TranscriptItemView({
   agentName,
   agentPubkey,
   item,
+  onExpansionChange,
   profiles,
+  expanded,
 }: AgentTranscriptIdentityProps & {
   item: TranscriptItem;
   profiles?: UserProfileLookup;
+  expanded?: boolean;
+  onExpansionChange?: (expanded: boolean) => void;
 }) {
   return (
     <TranscriptActivityItem
       agentAvatarUrl={agentAvatarUrl}
       agentName={agentName}
       agentPubkey={agentPubkey}
+      expanded={expanded}
       item={item}
+      onExpansionChange={onExpansionChange}
       profiles={profiles}
     />
   );
diff --git a/desktop/src/features/agents/ui/TranscriptToolRunGroup.tsx b/desktop/src/features/agents/ui/TranscriptToolRunGroup.tsx
index 57ebc86677..7fa0c7265f 100644
--- a/desktop/src/features/agents/ui/TranscriptToolRunGroup.tsx
+++ b/desktop/src/features/agents/ui/TranscriptToolRunGroup.tsx
@@ -23,6 +23,7 @@ import {
 import {
   setToolRunGroupExpanded,
   setToolRunGroupInternalStepsShown,
+  setToolRunGroupItemExpanded,
 } from "./agentSessionToolRunViewState";
 import { useToolRunGroupViewState } from "./useToolRunGroupViewState";
 import { formatTranscriptTimestampTitle } from "./agentSessionUtils";
@@ -121,7 +122,13 @@ export type TranscriptToolRunGroupProps = {
   label: React.ReactNode;
   showTimestamp: boolean;
   /** Renders one child segment. Passed in to avoid a list↔group import cycle. */
-  renderChild: (child: TranscriptToolRunChildSegment) => React.ReactNode;
+  renderChild: (
+    child: TranscriptToolRunChildSegment,
+    expansion?: {
+      expanded: boolean;
+      onExpansionChange: (expanded: boolean) => void;
+    },
+  ) => React.ReactNode;
 };
 
 /**
@@ -200,7 +207,24 @@ export function TranscriptToolRunGroup({
         {label}
         <ToolRunGroupStatusBadge failureCount={failureCount} status={status} />
         <ActivityRowContent className="flex flex-col gap-0.5">
-          {visibleChildren.map((child) => renderChild(child))}
+          {visibleChildren.map((child) =>
+            renderChild(
+              child,
+              child.kind === "item" && child.item.type === "tool"
+                ? {
+                    expanded: state.expandedItemIds.includes(child.item.id),
+                    onExpansionChange: (expanded) =>
+                      update((previous) =>
+                        setToolRunGroupItemExpanded(
+                          previous,
+                          child.item.id,
+                          expanded,
+                        ),
+                      ),
+                  }
+                : undefined,
+            ),
+          )}
           {hiddenItems.length > 0 ? (
             <button
               className="mt-0.5 self-start text-xs text-muted-foreground underline decoration-dotted hover:text-foreground"
diff --git a/desktop/src/features/agents/ui/activityRenderClasses/types.ts b/desktop/src/features/agents/ui/activityRenderClasses/types.ts
index ad8aef0cb9..f1fd097675 100644
--- a/desktop/src/features/agents/ui/activityRenderClasses/types.ts
+++ b/desktop/src/features/agents/ui/activityRenderClasses/types.ts
@@ -12,6 +12,9 @@ export type AgentTranscriptIdentityProps = {
 export type ActivityRenderClassItemProps = AgentTranscriptIdentityProps & {
   item: TranscriptItem;
   profiles?: UserProfileLookup;
+  /** Controlled detail expansion for rows whose state must survive regrouping. */
+  expanded?: boolean;
+  onExpansionChange?: (expanded: boolean) => void;
 };
 
 export type ActivityRenderClassPresenter =
diff --git a/desktop/src/features/communities/useCommunityInit.ts b/desktop/src/features/communities/useCommunityInit.ts
index e792358713..2d9ff8a06c 100644
--- a/desktop/src/features/communities/useCommunityInit.ts
+++ b/desktop/src/features/communities/useCommunityInit.ts
@@ -29,6 +29,7 @@ import {
   restoreActiveAgentTurnsForCommunity,
 } from "@/features/agents/activeAgentTurnsStore";
 import { resetAgentWorkingSignal } from "@/features/agents/agentWorkingSignal";
+import { resetAgentSessionToolRunViewState } from "@/features/agents/ui/agentSessionToolRunViewStore";
 import { resetAgentObserverStore } from "@/features/agents/observerRelayStore";
 import { resetAvatarPresentations } from "@/features/profile/avatarPresentationStore";
 import { resetAvatarProfileSync } from "@/features/profile/avatarProfileSync";
@@ -60,6 +61,7 @@ async function resetCommunityState({
   resetRateLimitGate();
   clearAllDrafts();
   resetAgentObserverStore();
+  resetAgentSessionToolRunViewState();
   resetActiveAgentTurnsStore();
   resetAgentWorkingSignal();
   if (isTauri() && isMacPlatform()) {
diff --git a/desktop/tests/e2e/transcript-tool-run-quality.smoke.spec.ts b/desktop/tests/e2e/transcript-tool-run-quality.smoke.spec.ts
new file mode 100644
index 0000000000..f33a9bf342
--- /dev/null
+++ b/desktop/tests/e2e/transcript-tool-run-quality.smoke.spec.ts
@@ -0,0 +1,148 @@
+import { expect, test } from "@playwright/test";
+
+import { installMockBridge, TEST_IDENTITIES } from "../helpers/bridge";
+
+const AGENT_PUBKEY = TEST_IDENTITIES.tyler.pubkey;
+const CHANNEL_ID = "94a444a4-c0a3-5966-ab05-530c6ddc2301";
+const NOW = new Date("2025-06-15T12:00:00Z").toISOString();
+
+const MANAGED_AGENTS = [
+  {
+    pubkey: AGENT_PUBKEY,
+    name: "Observer Agent",
+    status: "running" as const,
+    channelNames: ["agents"],
+  },
+];
+
+async function openFeed(page: import("@playwright/test").Page) {
+  await page.goto("/", { waitUntil: "domcontentloaded" });
+  await page.waitForFunction(
+    () => typeof window.__BUZZ_E2E_SEED_OBSERVER_EVENTS__ === "function",
+  );
+  await page.getByTestId("channel-agents").click();
+  const row = page
+    .getByTestId("message-row")
+    .filter({ has: page.getByText("Observer Agent", { exact: false }) })
+    .first();
+  await row.getByRole("button").first().click();
+  await page.getByTestId(`user-profile-view-activity-${AGENT_PUBKEY}`).click();
+  return page.getByTestId("agent-session-thread-panel");
+}
+
+function event(
+  seq: number,
+  toolCallId: string,
+  update: Record<string, unknown>,
+) {
+  return {
+    seq,
+    timestamp: NOW,
+    kind: "acp_read",
+    agentIndex: 0,
+    channelId: CHANNEL_ID,
+    sessionId: "session-quality",
+    turnId: "turn-quality",
+    payload: {
+      method: "session/update",
+      params: {
+        sessionId: "session-quality",
+        update: { toolCallId, ...update },
+      },
+    },
+  };
+}
+
+async function seed(
+  page: import("@playwright/test").Page,
+  events: ReturnType<typeof event>[],
+) {
+  await page.evaluate(
+    ({ pubkey, events }) =>
+      window.__BUZZ_E2E_SEED_OBSERVER_EVENTS__?.({
+        agentPubkey: pubkey,
+        events,
+      }),
+    { pubkey: AGENT_PUBKEY, events },
+  );
+}
+
+test("tool-run group stays readable through live completion and user expansion", async ({
+  page,
+}) => {
+  await installMockBridge(page, { managedAgents: MANAGED_AGENTS });
+  const panel = await openFeed(page);
+
+  await seed(page, [
+    event(1, "read-a", {
+      sessionUpdate: "tool_call",
+      status: "executing",
+      title: "read_file",
+      kind: "read_file",
+      rawInput: { path: "src/a.ts" },
+    }),
+    event(2, "read-b", {
+      sessionUpdate: "tool_call",
+      status: "executing",
+      title: "read_file",
+      kind: "read_file",
+      rawInput: { path: "src/b.ts" },
+    }),
+    event(3, "read-c", {
+      sessionUpdate: "tool_call",
+      status: "executing",
+      title: "read_file",
+      kind: "read_file",
+      rawInput: { path: "src/c.ts" },
+    }),
+  ]);
+
+  const group = panel.getByTestId("transcript-same-kind-summary");
+  await expect(group).toHaveAttribute("open", "");
+  await expect(
+    group.getByTestId("tool-run-group-status-running"),
+  ).toBeVisible();
+
+  await group.locator("summary").first().click();
+  await expect(group).not.toHaveAttribute("open", "");
+  await group.locator("summary").first().click();
+  await expect(group).toHaveAttribute("open", "");
+
+  await seed(page, [
+    event(4, "read-a", {
+      sessionUpdate: "tool_call_update",
+      status: "completed",
+      title: "read_file",
+      kind: "read_file",
+      rawInput: { path: "src/a.ts" },
+      rawOutput: "a",
+    }),
+    event(5, "read-b", {
+      sessionUpdate: "tool_call_update",
+      status: "completed",
+      title: "read_file",
+      kind: "read_file",
+      rawInput: { path: "src/b.ts" },
+      rawOutput: "b",
+    }),
+    event(6, "read-c", {
+      sessionUpdate: "tool_call_update",
+      status: "completed",
+      title: "read_file",
+      kind: "read_file",
+      rawInput: { path: "src/c.ts" },
+      rawOutput: "c",
+    }),
+  ]);
+
+  await expect(group).toHaveAttribute("open", "");
+  const child = group
+    .getByTestId("transcript-tool-item")
+    .first()
+    .locator("details");
+  await child.locator("summary").click();
+  await expect(child).toHaveAttribute("open", "");
+  await group.locator("summary").first().click();
+  await group.locator("summary").first().click();
+  await expect(child).toHaveAttribute("open", "");
+});