[codex] Polish inbox nested issue UI (#4959)

## Thinking Path

> - Paperclip orchestrates AI agents through issue lists and
issue-thread interactions
> - The inbox must preserve nested issue visibility and keyboard
navigation as work decomposes into deeper sub-issues
> - Some UI polish issues made nested rows harder to scan and pending
question cancellation less covered
> - The issue list also had a small test indentation regression around
load-more behavior
> - This pull request tightens nested inbox rendering and related
issue-thread/list polish
> - The benefit is a more reliable operator inbox for multi-level work
trees

## What Changed

- Included nested grandchild issues in inbox keyboard navigation and
recursive row rendering.
- Sort parent rows by descendant activity so active subtrees remain
visible.
- Removed extra inbox card background styling in favor of the page
surface.
- Added regression coverage for pending question cancellation.
- Cleaned up the issue-list load-more test indentation.

## Verification

- `pnpm exec vitest run ui/src/lib/inbox.test.ts
ui/src/components/IssueChatThread.test.tsx
ui/src/components/IssuesList.test.tsx`
- Screenshots were not captured in this PR split; the visible flow is
covered by focused component/helper tests and should get browser QA in
the follow-up issue.

## Risks

- Medium risk: nested inbox rendering and keyboard navigation are
user-visible. The changes are localized to inbox grouping/rendering
helpers and covered by targeted tests.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- OpenAI Codex, GPT-5 coding agent, tool use and local command
execution. Exact context window was not exposed in the runtime.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [ ] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

ui/src/components/IssueChatThread.test.tsx

@@ -1487,6 +1487,49 @@ describe("IssueChatThread", () => {
     });
   });
 
+  it("invokes the cancel callback for pending question interactions", async () => {
+    const root = createRoot(container);
+    const onCancelInteraction = vi.fn(async () => undefined);
+
+    await act(async () => {
+      root.render(
+        <MemoryRouter>
+          <IssueChatThread
+            comments={[]}
+            interactions={[createQuestionInteraction()]}
+            linkedRuns={[]}
+            timelineEvents={[]}
+            liveRuns={[]}
+            onAdd={async () => {}}
+            onCancelInteraction={onCancelInteraction}
+            showComposer={false}
+            enableLiveTranscriptPolling={false}
+          />
+        </MemoryRouter>,
+      );
+    });
+
+    const cancelButton = Array.from(container.querySelectorAll("button")).find((button) =>
+      button.textContent?.includes("Cancel question"),
+    );
+    expect(cancelButton).toBeTruthy();
+
+    await act(async () => {
+      cancelButton?.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+    });
+
+    expect(onCancelInteraction).toHaveBeenCalledWith(
+      expect.objectContaining({
+        id: "interaction-question-1",
+        kind: "ask_user_questions",
+      }),
+    );
+
+    act(() => {
+      root.unmount();
+    });
+  });
+
   it("folds expired request confirmations into an activity row by default", async () => {
     const root = createRoot(container);
 

ui/src/components/IssueThreadInteractionCard.tsx

@@ -807,8 +807,8 @@ function AskUserQuestionsCard({
                   ) : (
                     "Cancel question"
                   )}
-                </Button>
+                  </Button>
-              ) : null}
+                ) : null}
               <Button
                 size="sm"
                 disabled={!onSubmitInteractionAnswers || !canSubmit || working || cancelling}

ui/src/components/SwipeToArchive.tsx

@@ -153,7 +153,7 @@ export function SwipeToArchive({
         data-inbox-row-surface
         className={cn(
           "relative will-change-transform",
-          selected ? "bg-zinc-100 dark:bg-zinc-800" : "bg-card",
+          selected ? "bg-zinc-100 dark:bg-zinc-800" : "bg-background",
         )}
         style={{
           transform: `translate3d(${offsetX}px, 0, 0)`,

ui/src/lib/inbox.test.ts

@@ -634,6 +634,71 @@ describe("inbox helpers", () => {
     ]);
   });
 
+  it("keeps nested grandchild issues visible in keyboard navigation", () => {
+    const parentIssue = makeIssue("parent", true);
+    parentIssue.lastActivityAt = new Date("2026-03-11T01:00:00.000Z");
+    const childIssue = makeIssue("child", true);
+    childIssue.parentId = parentIssue.id;
+    childIssue.lastActivityAt = new Date("2026-03-11T02:00:00.000Z");
+    const grandchildIssue = makeIssue("grandchild", false);
+    grandchildIssue.parentId = childIssue.id;
+    grandchildIssue.lastActivityAt = new Date("2026-03-11T05:00:00.000Z");
+
+    const [section] = buildGroupedInboxSections(
+      getInboxWorkItems({ issues: [parentIssue, childIssue, grandchildIssue], approvals: [] }),
+      "none",
+      {},
+      { nestingEnabled: true },
+    );
+
+    expect(section?.displayItems.map((item) => item.kind === "issue" ? item.issue.id : "other")).toEqual([
+      parentIssue.id,
+    ]);
+    expect(section?.displayItems[0]?.timestamp).toBe(new Date("2026-03-11T05:00:00.000Z").getTime());
+
+    expect(
+      buildInboxKeyboardNavEntries([section!], new Set(), new Set()).map((entry) => entry.type === "top"
+        ? entry.item.kind === "issue" ? entry.item.issue.id : "other"
+        : entry.type === "child"
+          ? entry.issueId
+          : entry.groupKey),
+    ).toEqual([parentIssue.id, childIssue.id, grandchildIssue.id]);
+
+    expect(
+      buildInboxKeyboardNavEntries([section!], new Set(), new Set([childIssue.id])).map((entry) => entry.type === "top"
+        ? entry.item.kind === "issue" ? entry.item.issue.id : "other"
+        : entry.type === "child"
+          ? entry.issueId
+          : entry.groupKey),
+    ).toEqual([parentIssue.id, childIssue.id]);
+  });
+
+  it("stops cyclic child issue traversal when building keyboard navigation", () => {
+    const parentIssue = makeIssue("parent", true);
+    const childIssue = makeIssue("child", true);
+    childIssue.parentId = parentIssue.id;
+    parentIssue.parentId = childIssue.id;
+
+    const groupedSections = [
+      {
+        key: "workspace:default",
+        displayItems: [{ kind: "issue", timestamp: 2, issue: parentIssue } satisfies InboxWorkItem],
+        childrenByIssueId: new Map([
+          [parentIssue.id, [childIssue]],
+          [childIssue.id, [parentIssue]],
+        ]),
+      },
+    ];
+
+    expect(
+      buildInboxKeyboardNavEntries(groupedSections, new Set(), new Set()).map((entry) => entry.type === "top"
+        ? entry.item.kind === "issue" ? entry.item.issue.id : "other"
+        : entry.type === "child"
+          ? entry.issueId
+          : entry.groupKey),
+    ).toEqual([parentIssue.id, childIssue.id]);
+  });
+
   it("emits a group nav entry for labeled groups and omits children when the group is collapsed", () => {
     const visibleIssue = makeIssue("visible", true);
     const hiddenIssue = makeIssue("hidden", true);

ui/src/lib/inbox.ts

@@ -906,9 +906,26 @@ export function buildInboxNesting(items: InboxWorkItem[]): {
     }
   }
 
-  // Sort each child list by most recent activity
+  const subtreeActivityTimestamp = (issue: Issue, seen: ReadonlySet<string> = new Set()): number => {
+    const ownTimestamp = issueLastActivityTimestamp(issue);
+    if (seen.has(issue.id)) return ownTimestamp;
+    const nextSeen = new Set(seen);
+    nextSeen.add(issue.id);
+    const children = childrenByIssueId.get(issue.id) ?? [];
+    if (children.length === 0) return ownTimestamp;
+    return Math.max(
+      ownTimestamp,
+      ...children.map((child) => subtreeActivityTimestamp(child, nextSeen)),
+    );
+  };
+
+  // Sort each child list by most recent descendant activity, not just direct issue activity.
   for (const children of childrenByIssueId.values()) {
-    children.sort(sortIssuesByMostRecentActivity);
+    children.sort((a, b) => {
+      const activityDiff = subtreeActivityTimestamp(b) - subtreeActivityTimestamp(a);
+      if (activityDiff !== 0) return activityDiff;
+      return sortIssuesByMostRecentActivity(a, b);
+    });
   }
 
   // Build root issue items with group-adjusted timestamps
@@ -917,7 +934,7 @@ export function buildInboxNesting(items: InboxWorkItem[]): {
     .map((item) => {
       const children = childrenByIssueId.get(item.issue.id);
       if (!children?.length) return item;
-      const maxChildTs = Math.max(...children.map(issueLastActivityTimestamp));
+      const maxChildTs = Math.max(...children.map((child) => subtreeActivityTimestamp(child)));
       return { ...item, timestamp: Math.max(item.timestamp, maxChildTs) };
     });
 
@@ -985,6 +1002,23 @@ export function buildInboxKeyboardNavEntries(
     }
     if (isCollapsed) continue;
 
+    const addIssueChildren = (issueId: string, seen: ReadonlySet<string>) => {
+      const children = group.childrenByIssueId.get(issueId);
+      if (!children?.length || collapsedInboxParents.has(issueId)) return;
+
+      for (const child of children) {
+        if (seen.has(child.id)) continue;
+        const nextSeen = new Set(seen);
+        nextSeen.add(child.id);
+        entries.push({
+          type: "child",
+          issueId: child.id,
+          issue: child,
+        });
+        addIssueChildren(child.id, nextSeen);
+      }
+    };
+
     for (const item of group.displayItems) {
       entries.push({
         type: "top",
@@ -993,17 +1027,7 @@ export function buildInboxKeyboardNavEntries(
       });
 
       if (item.kind !== "issue") continue;
-
+      addIssueChildren(item.issue.id, new Set([item.issue.id]));
-      const children = group.childrenByIssueId.get(item.issue.id);
-      if (!children?.length || collapsedInboxParents.has(item.issue.id)) continue;
-
-      for (const child of children) {
-        entries.push({
-          type: "child",
-          issueId: child.id,
-          issue: child,
-        });
-      }
     }
   }
 

ui/src/pages/Inbox.tsx

@@ -2122,7 +2122,7 @@ export function Inbox() {
         <>
           {showSeparatorBefore("work_items") && <Separator />}
           <div>
-            <div ref={listRef} className="overflow-hidden rounded-xl bg-card">
+            <div ref={listRef} className="overflow-hidden rounded-xl">
               {(() => {
                 const renderInboxIssue = ({
                   issue,
@@ -2436,6 +2436,55 @@ export function Inbox() {
                     const hasChildren = childIssues.length > 0;
                     const isExpanded = hasChildren && !collapsedInboxParents.has(issue.id);
                     const canArchiveIssue = canArchiveFromTab && group.searchSection === "none";
+                    const renderChildIssueRows = (
+                      children: Issue[],
+                      depth: number,
+                      seen: ReadonlySet<string>,
+                    ): ReactNode[] =>
+                      children.flatMap((child) => {
+                        if (seen.has(child.id)) return [];
+                        const nextSeen = new Set(seen);
+                        nextSeen.add(child.id);
+                        const childNavIdx = childFlatIndex.get(child.id) ?? -1;
+                        const isChildSelected = selectedIndex === childNavIdx;
+                        const grandchildIssues = group.childrenByIssueId.get(child.id) ?? [];
+                        const childHasChildren = grandchildIssues.length > 0;
+                        const childIsExpanded = childHasChildren && !collapsedInboxParents.has(child.id);
+                        const childRow = renderInboxIssue({
+                          issue: child,
+                          depth,
+                          selected: isChildSelected,
+                          hasChildren: childHasChildren,
+                          isExpanded: childIsExpanded,
+                          childCount: grandchildIssues.length,
+                          collapseParentId: child.id,
+                          allowArchive: canArchiveIssue,
+                        });
+                        const isChildArchiving = archivingIssueIds.has(child.id);
+                        const row = (
+                          <div
+                            key={`sel-issue:${child.id}`}
+                            data-inbox-item
+                            className="relative"
+                            onClick={() => setSelectedIndex(childNavIdx)}
+                          >
+                            {canArchiveIssue ? (
+                              <SwipeToArchive
+                                key={`issue:${child.id}`}
+                                selected={isChildSelected}
+                                disabled={isChildArchiving || archiveIssueMutation.isPending}
+                                onArchive={() => archiveIssueMutation.mutate(child.id)}
+                              >
+                                {childRow}
+                              </SwipeToArchive>
+                            ) : childRow}
+                          </div>
+                        );
+
+                        return childIsExpanded
+                          ? [row, ...renderChildIssueRows(grandchildIssues, depth + 1, nextSeen)]
+                          : [row];
+                      });
                     const parentRow = renderInboxIssue({
                       issue,
                       depth: 0,
@@ -2459,36 +2508,7 @@ export function Inbox() {
                     ) : parentRow));
 
                     if (isExpanded) {
-                      for (const child of childIssues) {
+                      elements.push(...renderChildIssueRows(childIssues, 1, new Set([issue.id])));
-                        const childNavIdx = childFlatIndex.get(child.id) ?? -1;
-                        const isChildSelected = selectedIndex === childNavIdx;
-                        const childRow = renderInboxIssue({
-                          issue: child,
-                          depth: 1,
-                          selected: isChildSelected,
-                          allowArchive: canArchiveIssue,
-                        });
-                        const isChildArchiving = archivingIssueIds.has(child.id);
-                        elements.push(
-                          <div
-                            key={`sel-issue:${child.id}`}
-                            data-inbox-item
-                            className="relative"
-                            onClick={() => setSelectedIndex(childNavIdx)}
-                          >
-                            {canArchiveIssue ? (
-                              <SwipeToArchive
-                                key={`issue:${child.id}`}
-                                selected={isChildSelected}
-                                disabled={isChildArchiving || archiveIssueMutation.isPending}
-                                onArchive={() => archiveIssueMutation.mutate(child.id)}
-                              >
-                                {childRow}
-                              </SwipeToArchive>
-                            ) : childRow}
-                          </div>,
-                        );
-                      }
                     }
                   }