[codex] Improve issue thread review flow (#4381)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Issue detail is where operators coordinate review, approvals, and
follow-up work with active runs
> - That thread UI needs to surface blockers, descendants, review
handoffs, and reply ergonomics clearly enough for humans to guide agent
work
> - Several small gaps in the issue-thread flow were making review and
navigation clunkier than necessary
> - This pull request improves the reply composer, descendant/blocker
presentation, interaction folding, and review-request handoff plumbing
together as one cohesive issue-thread workflow slice
> - The benefit is a cleaner operator review loop without changing the
broader task model

## What Changed

- restored and refined the floating reply composer behavior in the issue
thread
- folded expired confirmation interactions and improved post-submit
thread scrolling behavior
- surfaced descendant issue context and inline blocker/paused-assignee
notices on the issue detail view
- tightened large-board first paint behavior in `IssuesList`
- added loose review-request handoffs through the issue
execution-policy/update path and covered them with tests

## Verification

- `pnpm vitest run ui/src/pages/IssueDetail.test.tsx`
- `pnpm vitest run server/src/__tests__/issues-service.test.ts
server/src/__tests__/issue-execution-policy.test.ts`
- `pnpm exec vitest run --project @paperclipai/ui
ui/src/components/IssueChatThread.test.tsx
ui/src/components/IssueProperties.test.tsx
ui/src/components/IssuesList.test.tsx ui/src/lib/issue-tree.test.ts
ui/src/api/issues.test.ts`
- `pnpm exec vitest run --project @paperclipai/adapter-utils
packages/adapter-utils/src/server-utils.test.ts`
- `pnpm exec vitest run --project @paperclipai/server
server/src/__tests__/issue-comment-reopen-routes.test.ts -t "coerces
executor handoff patches into workflow-controlled review wakes|wakes the
return assignee with execution_changes_requested"`
- `pnpm exec vitest run --project @paperclipai/server
server/src/__tests__/issue-execution-policy.test.ts
server/src/__tests__/issues-service.test.ts`

## Visual Evidence

- UI layout changes are covered by the focused issue-thread component
and issue-detail tests listed above. Browser screenshots were not
attachable from this automated greploop environment, so reviewers should
use the running preview for final visual confirmation.

## Risks

- Moderate UI-flow risk: these changes touch the issue detail experience
in multiple spots, so regressions would most likely show up as
thread-layout quirks or incorrect review-handoff behavior

> 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-based coding agent with tool use and code execution
in the Codex CLI environment

## 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
- [x] If this change affects the UI, I have included before/after
screenshots or documented the visual verification path
- [ ] 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/pages/IssueDetail.test.tsx

@@ -850,8 +850,8 @@ describe("IssueDetail", () => {
     };
 
     mockIssuesApi.get.mockResolvedValue(createIssue());
-    mockIssuesApi.list.mockImplementation((_companyId, filters?: { parentId?: string }) =>
-      Promise.resolve(filters?.parentId === "issue-1" ? [childIssue] : []),
+    mockIssuesApi.list.mockImplementation((_companyId, filters?: { descendantOf?: string }) =>
+      Promise.resolve(filters?.descendantOf === "issue-1" ? [childIssue] : []),
     );
     mockIssuesApi.getTreeControlState.mockImplementation(() =>
       Promise.resolve({ activePauseHold: activePauseHoldState }),
@@ -937,8 +937,8 @@ describe("IssueDetail", () => {
     });
 
     mockIssuesApi.get.mockResolvedValue(createIssue());
-    mockIssuesApi.list.mockImplementation((_companyId, filters?: { parentId?: string }) =>
-      Promise.resolve(filters?.parentId === "issue-1" ? [childIssue] : []),
+    mockIssuesApi.list.mockImplementation((_companyId, filters?: { descendantOf?: string }) =>
+      Promise.resolve(filters?.descendantOf === "issue-1" ? [childIssue] : []),
     );
     mockIssuesApi.previewTreeControl.mockResolvedValue(pausePreview);
     mockIssuesApi.createTreeHold.mockResolvedValue({ hold: pauseHold, preview: pausePreview });
@@ -1031,8 +1031,8 @@ describe("IssueDetail", () => {
     });
 
     mockIssuesApi.get.mockResolvedValue(createIssue());
-    mockIssuesApi.list.mockImplementation((_companyId, filters?: { parentId?: string }) =>
-      Promise.resolve(filters?.parentId === "issue-1" ? [childIssue] : []),
+    mockIssuesApi.list.mockImplementation((_companyId, filters?: { descendantOf?: string }) =>
+      Promise.resolve(filters?.descendantOf === "issue-1" ? [childIssue] : []),
     );
     mockIssuesApi.listTreeHolds.mockImplementation((_issueId, filters?: { mode?: string }) =>
       Promise.resolve(filters?.mode === "cancel" ? [cancelHold] : []),
@@ -1106,8 +1106,8 @@ describe("IssueDetail", () => {
     });
 
     mockIssuesApi.get.mockResolvedValue(createIssue());
-    mockIssuesApi.list.mockImplementation((_companyId, filters?: { parentId?: string }) =>
-      Promise.resolve(filters?.parentId === "issue-1" ? [childIssue] : []),
+    mockIssuesApi.list.mockImplementation((_companyId, filters?: { descendantOf?: string }) =>
+      Promise.resolve(filters?.descendantOf === "issue-1" ? [childIssue] : []),
     );
     mockIssuesApi.previewTreeControl.mockResolvedValue(createCancelPreview(24));
     mockAuthApi.getSession.mockResolvedValue({

ui/src/pages/IssueDetail.tsx

@@ -98,6 +98,7 @@ import { Textarea } from "@/components/ui/textarea";
 import { formatIssueActivityAction } from "@/lib/activity-format";
 import { buildIssuePropertiesPanelKey } from "../lib/issue-properties-panel-key";
 import { shouldRenderRichSubIssuesSection } from "../lib/issue-detail-subissues";
+import { filterIssueDescendants } from "../lib/issue-tree";
 import { buildSubIssueDefaultsForViewer } from "../lib/subIssueDefaults";
 import {
   Activity as ActivityIcon,
@@ -1132,9 +1133,9 @@ export function IssueDetail() {
   const { data: rawChildIssues = [], isLoading: childIssuesLoading } = useQuery({
     queryKey:
       issue?.id && resolvedCompanyId
-        ? queryKeys.issues.listByParent(resolvedCompanyId, issue.id)
+        ? queryKeys.issues.listByDescendantRoot(resolvedCompanyId, issue.id)
         : ["issues", "parent", "pending"],
-    queryFn: () => issuesApi.list(resolvedCompanyId!, { parentId: issue!.id }),
+    queryFn: () => issuesApi.list(resolvedCompanyId!, { descendantOf: issue!.id }),
     enabled: !!resolvedCompanyId && !!issue?.id,
     placeholderData: keepPreviousDataForSameQueryTail<Issue[]>(issue?.id ?? "pending"),
   });
@@ -1286,8 +1287,11 @@ export function IssueDetail() {
     [issue?.project, issue?.projectId, orderedProjects],
   );
   const childIssues = useMemo(
-    () => [...rawChildIssues].sort((a, b) => new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime()),
-    [rawChildIssues],
+    () => {
+      const descendants = issue?.id ? filterIssueDescendants(issue.id, rawChildIssues) : rawChildIssues;
+      return [...descendants].sort((a, b) => new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime());
+    },
+    [issue?.id, rawChildIssues],
   );
   const liveIssueIds = useMemo(() => collectLiveIssueIds(companyLiveRuns), [companyLiveRuns]);
   const issuePanelKey = useMemo(
@@ -3133,7 +3137,8 @@ export function IssueDetail() {
             projectId={issue.projectId ?? undefined}
             viewStateKey={`paperclip:issue-detail:${issue.id}:subissues-view`}
             issueLinkState={resolvedIssueDetailState ?? location.state}
-            searchFilters={{ parentId: issue.id }}
+            searchFilters={{ descendantOf: issue.id }}
+            searchWithinLoadedIssues
             baseCreateIssueDefaults={buildSubIssueDefaultsForViewer(issue, currentUserId)}
             createIssueLabel="Sub-issue"
             onUpdateIssue={handleChildIssueUpdate}