Fix slash popup navigation and restore composer dividers

- Use keymap list.move_up/down for slash popup traversal instead of
  hardcoded Ctrl-P/N, fixing the bug where popup only moved upward.
- Open slash popup immediately on bare `/` without waiting for
  paste-burst flush timeout.
- Deduplicate service tier commands that collide with builtin slash
  command names (e.g. `fast`).
- Restore top/bottom border on the chat composer area to visually
  separate history from input.
- Clarify `/subagents` description: closed rows are reviewable and
  do not imply spawn quota is still held.
- Support CODEX_RESUME_COMMAND_NAME env var for fork-specific resume
  command formatting.
- Update FEATURES.md and README with subagents semantics clarification.

Author: LEON-gittech

FEATURES.md

@@ -17,15 +17,6 @@ Fast-moving prompt packs, hooks, setup flows, and project policies are better ha
 
 ## Implemented Features
 
-## Release Notes
-
-### 0.131.1 - 2026-05-19
-
-- Merge upstream Codex 0.131.0 into Open Codex.
-- Preserve fork runtime features across the merge: memory overlay/browser, persistent `Shift+Tab` speed toggle, Claude-style rewind/revoke, `/btw`, `/effort`, subagent quota reclamation, background subagent tracking, git attribution, and inline update release notes.
-- Restore fork-correct npm packaging and update diagnostics so install/update guidance targets `@leonw24/open-codex`.
-- Keep the release publishable through the local `release-fast` path with concrete GitHub release notes for the startup update prompt.
-
 ### TUI readability and turn correctness
 
 | Feature | User-facing behavior | Main entry points | Notes |
@@ -68,7 +59,7 @@ Fast-moving prompt packs, hooks, setup flows, and project policies are better ha
 | --- | --- | --- | --- |
 | Nonblocking terminal tasks | Long-running terminal commands can continue in the background while chat continues. | `Ctrl+B`, task panel | Completed output remains available in history. |
 | Background subagent tracking | Spawned agents appear as background activity with role, status, runtime, progress, and task context. | Task panel, spawn/wait tool handling | Foreground `Working` state is separate from background counts. |
-| `/agent` and `/subagents` split | `/agent` lists agent profiles, while `/subagents` remains the active/resumable subagent view. | Slash commands | Keeps profile discovery separate from thread switching. |
+| `/agent` and `/subagents` split | `/agent` lists agent profiles, while `/subagents` opens the subagent thread picker for live, resumable, and reviewable threads. | Slash commands | Closed review rows do not imply spawn quota is still held; quota availability is determined by active/interrupted runtime handles. |
 | Subagent completion wakeups | Completed subagent work wakes the parent turn without requiring manual wait/close. | Core completion events | Added/fixed around `8670c2c842`. |
 | Subagent quota reclamation | Completed subagents are reclaimed from spawn quota, and spawn performs opportunistic cleanup when quota is exhausted. | Subagent runtime, spawn path | Interrupted subagents remain active/resumable quota holders. Fixed by `5348fb6fcd`. |
 | Parallel-first subagent policy | Complex tasks are encouraged to use independent read-only exploration, review, validation, and release-check lanes. | `~/.codex/AGENTS.md`, `docs/parallel-first-agent-execution.md` | Instruction-policy feature, not a hardcoded scheduler. |
@@ -97,6 +88,15 @@ Fast-moving prompt packs, hooks, setup flows, and project policies are better ha
 | `/btw` side questions | Ask quick side questions without taking over the primary chat thread. | `/btw <question>` | Runs as an inline hidden thread with expected model, effort, permission, and tool behavior. |
 | Default commit attribution | Open Codex can apply the fork's commit attribution identity by default. | git attribution extension/config | Implemented before the recent 0.130.x release series. |
 
+## Release Notes
+
+### 0.131.1 - 2026-05-19
+
+- Merge upstream Codex 0.131.0 into Open Codex.
+- Preserve fork runtime features across the merge: memory overlay/browser, persistent `Shift+Tab` speed toggle, Claude-style rewind/revoke, `/btw`, `/effort`, subagent quota reclamation, background subagent tracking, git attribution, and inline update release notes.
+- Restore fork-correct npm packaging and update diagnostics so install/update guidance targets `@leonw24/open-codex`.
+- Keep the release publishable through the local `release-fast` path with concrete GitHub release notes for the startup update prompt.
+
 ## Recently Important Fixes
 
 | Commit | Date | Summary |

README.md

@@ -174,9 +174,9 @@ The shared interaction model is:
 - `Enter` opens details, `x` stops the selected stoppable background item, and `Esc`/`Left` closes the panel.
 - the status line keeps foreground `Working` state separate from background subagent/terminal counts.
 - terminal details show runtime and recent output; subagent details show role, task, status, runtime, progress, and task-boundary context.
-- `/agent` shows available agent profiles, while `/subagents` keeps the subagent thread picker/switching workflow.
+- `/agent` shows available agent profiles, while `/subagents` opens the subagent thread picker/switching workflow for live, resumable, and closed-but-reviewable threads.
 - completed subagent work wakes the parent turn through a core completion event, so results can be integrated without manually calling `wait_agent` or closing the agent.
-- completed subagents are reclaimed from spawn quota when they reach a final state, and the spawn path performs opportunistic cleanup before reporting that no quota is available. Interrupted subagents remain visible as active quota holders because they may still be resumed; `/subagents` is therefore the active/resumable subagent view, not a stale-handle inventory.
+- completed subagents are reclaimed from spawn quota when they reach a final state, and the spawn path performs opportunistic cleanup before reporting that no quota is available. Interrupted subagents remain active quota holders because they may still be resumed; closed `/subagents` rows are retained for review/switching context and should not be read as proof that spawn quota is still held.
 - completed background command output is preserved in history without pulling the task back into the foreground.
 
 This is the essential interaction change behind the Claude Code-style behavior: background work stays visible and controllable, but it no longer blocks normal chat flow.
@@ -476,9 +476,9 @@ Codex CLI 是开源的，但上游仓库当前对外部代码贡献采用 invita
 - `Enter` 打开详情，`x` 停止当前选中的 stoppable 后台项，`Esc`/`Left` 关闭 panel。
 - status line 会把前台 `Working` 状态和后台 subagent/terminal 数量分开显示。
 - terminal detail 展示运行时间和最近输出；subagent detail 展示 role、task、status、运行时间、progress 和任务边界信息。
-- `/agent` 用于查看可用 agent profiles，`/subagents` 保留 subagent thread picker / 切换工作流。
+- `/agent` 用于查看可用 agent profiles，`/subagents` 打开 subagent thread picker / 切换工作流，覆盖 live、resumable、以及 closed-but-reviewable threads。
 - subagent 完成后会通过 core completion event 唤醒 parent turn，因此不需要手动调用 `wait_agent` 或关闭 agent 才能继续整合结果。
-- completed subagent 到达 final state 后会从 spawn quota 中回收；当 spawn 没有可用 quota 时，主线程会先做 opportunistic cleanup 再返回 quota 不足。Interrupted subagent 仍会作为 active quota holder 保留，因为它们可能被 resume；因此 `/subagents` 的语义是 active/resumable subagent view，而不是僵尸 handle 列表。
+- completed subagent 到达 final state 后会从 spawn quota 中回收；当 spawn 没有可用 quota 时，主线程会先做 opportunistic cleanup 再返回 quota 不足。Interrupted subagent 仍会作为 active quota holder 保留，因为它们可能被 resume；closed `/subagents` rows 会保留用于 review / switching context，不应被理解为 spawn quota 仍被占用。
 - background command 完成后会保留输出到 history，但不会把任务重新拉回前台。
 
 这是 Claude Code 风格体验背后的本质交互变化：后台工作仍然可见、可管理，但不会阻塞正常聊天流。

codex-rs/tui/src/app/agent_navigation.rs

@@ -242,7 +242,7 @@ impl AgentNavigationState {
         let previous: Span<'static> = previous_agent_shortcut().into();
         let next: Span<'static> = next_agent_shortcut().into();
         format!(
-            "Select an agent to watch. {} previous, {} next.",
+            "Select an agent thread to watch. Closed rows are reviewable; they do not mean spawn quota is still held. {} previous, {} next.",
             previous.content, next.content
         )
     }