FN-5845: fix mobile agent log scroll and add collapsible branch group card

Improve dashboard mobile log usability and make branch group cards collapsible for cleaner review workflows.

- preserve/restore AgentLogViewer scroll position when toggling mobile drawer and lock body scroll while open
- add collapse/expand state to BranchGroupCard with a summary header and hidden details when collapsed
- add regression tests for AgentLogViewer mobile scroll behavior and BranchGroupCard collapse interactions
- add a changeset and dashboard guide note for the new branch group card behavior

Files changed:
 .changeset/fn-5845-branch-group-collapse.md        |  5 ++
 docs/dashboard-guide.md                            |  1 +
 .../dashboard/app/components/AgentLogViewer.tsx    | 21 ++++++++
 .../dashboard/app/components/BranchGroupCard.css   | 23 ++++++++
 .../dashboard/app/components/BranchGroupCard.tsx   | 63 +++++++++++++++++-----
 .../components/__tests__/AgentLogViewer.test.tsx   | 48 +++++++++++++++++
 .../components/__tests__/BranchGroupCard.test.tsx  | 18 +++++++
 7 files changed, 166 insertions(+), 13 deletions(-)

Fusion-Task-Id: FN-5845

Fusion-Task-Lineage: 6a0f2967-5df8-4761-ae6c-50991f01ab78

.changeset/fn-5845-branch-group-collapse.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Fix mobile Task Detail Logs scrolling for branch-group tasks by making the branch-group card collapsible and re-pinning the agent log viewer when its container height changes.

docs/dashboard-guide.md

@@ -1135,6 +1135,7 @@ UI surfaces:
 - Task cards show grouped/shared branch metadata for grouped tasks.
 - Clicking either grouped badge opens the dedicated **Group Task Modal** for that branch group.
 - Task detail renders a branch-group card with member landed progress.
+- In Task Detail Logs on mobile, the branch-group card includes a collapse/expand toggle so logs can reclaim vertical space while keeping group summary progress visible.
 
 The Group Task Modal shows shared branch name/status, member list (`taskId`, title, column, landed state), quick links to open each member task detail, completion progress (`X of Y members finished`), and tracked PR state when present. It live-refreshes from the same dashboard task-update stream and ignores stale cross-project events.
 

packages/dashboard/app/components/AgentLogViewer.tsx

@@ -393,6 +393,27 @@ export function AgentLogViewer({
     setIsFollowing(true);
   }, []);
 
+  useEffect(() => {
+    if (typeof ResizeObserver === "undefined") {
+      return;
+    }
+
+    const container = containerRef.current;
+    if (!container) {
+      return;
+    }
+
+    const observer = new ResizeObserver(() => {
+      if (!isFollowing) {
+        return;
+      }
+      container.scrollTop = container.scrollHeight;
+    });
+
+    observer.observe(container);
+    return () => observer.disconnect();
+  }, [isFollowing]);
+
   // Escape key handler to exit fullscreen mode
   const handleKeyDown = useCallback((e: KeyboardEvent) => {
     if (e.key === "Escape" && isFullscreen) {

packages/dashboard/app/components/BranchGroupCard.css

@@ -21,10 +21,28 @@
   gap: var(--space-xs);
 }
 
+.branch-group-card-header-meta {
+  display: inline-flex;
+  align-items: center;
+  gap: var(--space-xs);
+}
+
 .branch-group-card-badge {
   background: var(--surface-elevated);
 }
 
+.branch-group-card-header-meta .btn {
+  flex-shrink: 0;
+}
+
+.branch-group-card-header-meta .btn-icon {
+  padding: calc(var(--space-xs) / 2);
+}
+
+.branch-group-card-header-meta .btn-icon svg {
+  display: block;
+}
+
 .branch-group-card-progress-text {
   color: var(--text-muted);
   font-size: var(--font-size-sm);
@@ -80,4 +98,9 @@
     flex-direction: column;
     align-items: flex-start;
   }
+
+  .branch-group-card-header-meta {
+    width: 100%;
+    justify-content: space-between;
+  }
 }

packages/dashboard/app/components/BranchGroupCard.tsx

@@ -1,6 +1,6 @@
 import "./BranchGroupCard.css";
 import { useCallback, useEffect, useMemo, useState } from "react";
-import { CheckCircle2, CircleDashed, ExternalLink, GitBranch, GitPullRequest, Loader2 } from "lucide-react";
+import { CheckCircle2, ChevronDown, ChevronRight, CircleDashed, ExternalLink, GitBranch, GitPullRequest, Loader2 } from "lucide-react";
 import type { BranchGroupSummary } from "../api";
 import { apiGetBranchGroup, apiPromoteBranchGroup } from "../api";
 import { subscribeSse } from "../sse-bus";
@@ -15,6 +15,7 @@ export function BranchGroupCard({ groupId, projectId }: BranchGroupCardProps) {
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
   const [promoting, setPromoting] = useState(false);
+  const [collapsed, setCollapsed] = useState(false);
 
   const loadGroup = useCallback(async () => {
     try {
@@ -34,6 +35,29 @@ export function BranchGroupCard({ groupId, projectId }: BranchGroupCardProps) {
     void loadGroup();
   }, [loadGroup]);
 
+  useEffect(() => {
+    if (typeof window === "undefined" || typeof window.matchMedia !== "function") {
+      return;
+    }
+    const mediaQuery = window.matchMedia("(max-width: 768px)");
+    const syncCollapsed = (matches: boolean) => {
+      setCollapsed(matches);
+    };
+
+    syncCollapsed(mediaQuery.matches);
+    const onMediaChange = (event: MediaQueryListEvent) => {
+      syncCollapsed(event.matches);
+    };
+
+    if (typeof mediaQuery.addEventListener === "function") {
+      mediaQuery.addEventListener("change", onMediaChange);
+      return () => mediaQuery.removeEventListener("change", onMediaChange);
+    }
+
+    mediaQuery.addListener(onMediaChange);
+    return () => mediaQuery.removeListener(onMediaChange);
+  }, []);
+
   useEffect(() => {
     const query = projectId ? `?projectId=${encodeURIComponent(projectId)}` : "";
     return subscribeSse(`/api/events${query}`, {
@@ -83,24 +107,37 @@ export function BranchGroupCard({ groupId, projectId }: BranchGroupCardProps) {
           <GitBranch size={14} />
           <strong>{group.branchName}</strong>
         </div>
-        <span className="badge branch-group-card-badge">Group {group.id}</span>
+        <div className="branch-group-card-header-meta">
+          <span className="badge branch-group-card-badge">Group {group.id}</span>
+          <button
+            type="button"
+            className="btn btn-icon"
+            onClick={() => setCollapsed((value) => !value)}
+            aria-expanded={!collapsed}
+            aria-label={collapsed ? "Expand branch group" : "Collapse branch group"}
+          >
+            {collapsed ? <ChevronRight size={14} /> : <ChevronDown size={14} />}
+          </button>
+        </div>
       </header>
       <div className="branch-group-card-progress-text">{completionText}</div>
       <div className="branch-group-card-progress" role="progressbar" aria-valuenow={group.completion.landed} aria-valuemin={0} aria-valuemax={group.completion.total}>
         <span className="branch-group-card-progress-fill" style={{ width: `${completionPercent}%` }} />
       </div>
 
-      <ul className="branch-group-card-members">
-        {group.members.map((member) => (
-          <li key={member.taskId} className="branch-group-card-member">
-            <span className={`status-dot ${member.landed ? "status-dot--online" : "status-dot--pending"}`} />
-            <span className="branch-group-card-member-title">{member.taskId} · {member.title}</span>
-            <span className="branch-group-card-member-status">{member.landed ? <CheckCircle2 size={14} /> : <CircleDashed size={14} />}</span>
-          </li>
-        ))}
-      </ul>
+      {!collapsed && (
+        <ul className="branch-group-card-members">
+          {group.members.map((member) => (
+            <li key={member.taskId} className="branch-group-card-member">
+              <span className={`status-dot ${member.landed ? "status-dot--online" : "status-dot--pending"}`} />
+              <span className="branch-group-card-member-title">{member.taskId} · {member.title}</span>
+              <span className="branch-group-card-member-status">{member.landed ? <CheckCircle2 size={14} /> : <CircleDashed size={14} />}</span>
+            </li>
+          ))}
+        </ul>
+      )}
 
-      {complete && (
+      {!collapsed && complete && (
         <div className="branch-group-card-actions">
           {group.prUrl && (
             <a className="btn" href={group.prUrl} target="_blank" rel="noreferrer">

packages/dashboard/app/components/__tests__/AgentLogViewer.test.tsx

@@ -1137,6 +1137,54 @@ describe("AgentLogViewer", () => {
       expect(viewer.scrollTop).toBe(1000);
       expect(screen.queryByTestId("agent-log-return-to-live")).toBeNull();
     });
+
+    it("re-pins to bottom on resize while following", () => {
+      const resizeCallbacks: Array<() => void> = [];
+      const originalResizeObserver = globalThis.ResizeObserver;
+
+      class ResizeObserverMock {
+        constructor(callback: ResizeObserverCallback) {
+          resizeCallbacks.push(() => callback([], this as unknown as ResizeObserver));
+        }
+
+        observe() {}
+        unobserve() {}
+        disconnect() {}
+      }
+
+      Object.defineProperty(globalThis, "ResizeObserver", {
+        configurable: true,
+        value: ResizeObserverMock,
+      });
+
+      try {
+        const entries = [
+          makeEntry({ text: "first", timestamp: "2026-01-01T00:00:00Z" }),
+          makeEntry({ text: "second", timestamp: "2026-01-01T00:00:01Z" }),
+        ];
+        const { container } = render(<AgentLogViewer entries={entries} loading={false} />);
+        const viewer = getScrollContainer(container);
+
+        Object.defineProperty(viewer, "scrollHeight", { configurable: true, value: 1200 });
+        Object.defineProperty(viewer, "clientHeight", { configurable: true, value: 200 });
+        viewer.scrollTop = 980;
+        fireEvent.scroll(viewer);
+
+        viewer.scrollTop = 640;
+        resizeCallbacks.forEach((callback) => callback());
+
+        expect(viewer.scrollTop).toBe(1200);
+      } finally {
+        if (originalResizeObserver) {
+          Object.defineProperty(globalThis, "ResizeObserver", {
+            configurable: true,
+            value: originalResizeObserver,
+          });
+        } else {
+          delete (globalThis as { ResizeObserver?: typeof ResizeObserver }).ResizeObserver;
+        }
+      }
+    });
   });
 
   describe("pagination placement", () => {

packages/dashboard/app/components/__tests__/BranchGroupCard.test.tsx

@@ -17,6 +17,8 @@ vi.mock("../../sse-bus", () => ({
 
 vi.mock("lucide-react", () => ({
   CheckCircle2: () => null,
+  ChevronDown: () => null,
+  ChevronRight: () => null,
   CircleDashed: () => null,
   ExternalLink: () => null,
   GitBranch: () => null,
@@ -93,4 +95,20 @@ describe("BranchGroupCard", () => {
     render(<BranchGroupCard groupId="BG-1" />);
     expect(await screen.findByRole("link", { name: /pr #9/i })).toBeInTheDocument();
   });
+
+  it("shows members by default and collapses via toggle", async () => {
+    apiGetBranchGroup.mockResolvedValue({ group: makeGroup() });
+    render(<BranchGroupCard groupId="BG-1" />);
+
+    expect(await screen.findByText("FN-1 · one")).toBeInTheDocument();
+
+    const toggle = screen.getByRole("button", { name: /collapse branch group/i });
+    expect(toggle).toHaveAttribute("aria-expanded", "true");
+
+    fireEvent.click(toggle);
+
+    expect(screen.getByRole("button", { name: /expand branch group/i })).toHaveAttribute("aria-expanded", "false");
+    expect(screen.queryByText("FN-1 · one")).toBeNull();
+    expect(screen.getByText("1 of 2 members finished")).toBeInTheDocument();
+  });
 });