[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>

server/src/routes/issues.ts

@@ -101,6 +101,7 @@ type ExecutionStageWakeContext = {
   stageType: ParsedExecutionState["currentStageType"];
   currentParticipant: ParsedExecutionState["currentParticipant"];
   returnAssignee: ParsedExecutionState["returnAssignee"];
+  reviewRequest: ParsedExecutionState["reviewRequest"];
   lastDecisionOutcome: ParsedExecutionState["lastDecisionOutcome"];
   allowedActions: string[];
 };
@@ -124,6 +125,7 @@ function buildExecutionStageWakeContext(input: {
     stageType: input.state.currentStageType,
     currentParticipant: input.state.currentParticipant,
     returnAssignee: input.state.returnAssignee,
+    reviewRequest: input.state.reviewRequest ?? null,
     lastDecisionOutcome: input.state.lastDecisionOutcome,
     allowedActions: input.allowedActions,
   };
@@ -831,6 +833,7 @@ export function issueRoutes(
       workspaceId: req.query.workspaceId as string | undefined,
       executionWorkspaceId: req.query.executionWorkspaceId as string | undefined,
       parentId: req.query.parentId as string | undefined,
+      descendantOf: req.query.descendantOf as string | undefined,
       labelId: req.query.labelId as string | undefined,
       originKind: req.query.originKind as string | undefined,
       originId: req.query.originId as string | undefined,
@@ -1787,6 +1790,7 @@ export function issueRoutes(
         : null;
     const {
       comment: commentBody,
+      reviewRequest,
       reopen: reopenRequested,
       interrupt: interruptRequested,
       hiddenAt: hiddenAtRaw,
@@ -1813,7 +1817,8 @@ export function issueRoutes(
         : false;
     let interruptedRunId: string | null = null;
     const closedExecutionWorkspace = await getClosedIssueExecutionWorkspace(existing);
-    const isAgentWorkUpdate = req.actor.type === "agent" && Object.keys(updateFields).length > 0;
+    const isAgentWorkUpdate =
+      req.actor.type === "agent" && (Object.keys(updateFields).length > 0 || reviewRequest !== undefined);
 
     if (closedExecutionWorkspace && (commentBody || isAgentWorkUpdate)) {
       respondClosedIssueExecutionWorkspace(res, closedExecutionWorkspace);
@@ -1887,6 +1892,7 @@ export function issueRoutes(
         userId: actor.actorType === "user" ? actor.actorId : null,
       },
       commentBody,
+      reviewRequest: reviewRequest === undefined ? undefined : reviewRequest,
     });
     const decisionId = transition.decision ? randomUUID() : null;
     if (decisionId) {
@@ -1900,6 +1906,20 @@ export function issueRoutes(
       };
     }
     Object.assign(updateFields, transition.patch);
+    if (reviewRequest !== undefined && transition.patch.executionState === undefined) {
+      const existingExecutionState = parseIssueExecutionState(existing.executionState);
+      if (!existingExecutionState || existingExecutionState.status !== "pending") {
+        if (reviewRequest !== null) {
+          res.status(422).json({ error: "reviewRequest requires an active review or approval stage" });
+          return;
+        }
+      } else {
+        updateFields.executionState = {
+          ...existingExecutionState,
+          reviewRequest,
+        };
+      }
+    }
 
     const nextAssigneeAgentId =
       updateFields.assigneeAgentId === undefined ? existing.assigneeAgentId : (updateFields.assigneeAgentId as string | null);