Agent Teams: bottom bar UI regression — TaskList, teammates nav, background tasks all intermittently hidden

Summary

Over the last 2–3 weeks, the CLI's bottom bar UI has progressively degraded. The TaskList, teammates navigation, and background tasks panel are all intermittently hidden or broken. The issue persists across multiple CLI version upgrades (currently on 2.1.85) with slight worsening over time (more symptoms appearing, working state occurring less frequently).

Symptoms

1. TaskList mostly hidden — The task list panel rarely renders. Toggling with ctrl+t is unreliable. Occasionally it flickers into view briefly, confirming it's not an intentional removal.

1. Teammates navigation unreliable — Sometimes teammates appear in the bottom bar, sometimes they don't. When they do appear, there are often duplicate phantom buttons for each teammate — only the "real" buttons work. Arrow-keying through the list skips the phantom entries, but they still render, making all buttons tiny compressed columns.

1. Background Tasks UI inaccessible — The background task list that previously existed is completely blocked/unreachable.

1. Intermittent flickering — All three issues flicker between working and broken states, suggesting a rendering/state conflict rather than an intentional change.

Environment

• CLI version: 2.1.85
• Platform: macOS (Darwin 25.4.0, arm64 / M1 Pro)
• Shell: zsh
• Terminal: standard macOS terminal
• Agent Teams: enabled via CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1

Configuration (potentially relevant)

~/.claude/settings.json (redacted):

{
  "env": {
    "CLAUDE_CODE_ENABLE_PROMPT_SUGGESTION": "false",
    "CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS": "1",
    "CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC": "1"
  },
  "hooks": {
    "Stop": [{ "hooks": [{ "type": "command", "command": "<redacted>" }] }],
    "Notification": [
      { "hooks": [{ "type": "command", "command": "<redacted>" }] },
      { "matcher": "permission_prompt", "hooks": [{ "type": "command", "command": "<redacted>" }] },
      { "matcher": "idle_prompt", "hooks": [{ "type": "command", "command": "<redacted>" }] }
    ],
    "PreToolUse": [
      { "matcher": "Skill", "hooks": [{ "type": "command", "command": "<redacted>" }] }
    ],
    "SubagentStart": [{ "hooks": [{ "type": "command", "command": "<redacted>" }] }],
    "UserPromptSubmit": [{ "hooks": [{ "type": "command", "command": "<redacted>" }] }]
  },
  "statusLine": {
    "type": "command",
    "command": "~/.claude/statusline-command.sh"
  },
  "enabledPlugins": {
    "rust-analyzer-lsp@claude-plugins-official": true,
    "typescript-lsp@claude-plugins-official": true,
    "swift-lsp@claude-plugins-official": true,
    "plugin-dev@claude-plugins-official": true,
    "ebrain": true,
    "ebrain@ebrain-local": true,
    "hq@cooksatlas-hq": true,
    "cooksatlas-design@cooksatlas-design": true
  },
  "alwaysThinkingEnabled": false,
  "effortLevel": "high",
  "autoUpdatesChannel": "latest",
  "skipDangerousModePermissionPrompt": true
}

Note: The statusLine.command references ~/.claude/statusline-command.sh but the file has been renamed to .disabled — this is a dangling reference that may be contributing to the rendering issues.

Multiple plugins are enabled (8 total), including custom plugins. Multiple MCP servers configured (Slack, Notion, Linear, GitHub, Figma — all with defer_loading: true).

Reproduction

• Happens across all projects, not project-specific
• Start a session with Agent Teams enabled
• Create a team and spawn teammates
• Observe the bottom bar — TaskList and teammate buttons intermittently disappear
• Try ctrl+t to toggle views — often unresponsive
• When teammates do render, duplicate phantom buttons appear

Potentially related issues

• #27919 — Task list UI stops advancing after auto-compact
• #10999 / #16923 / #18827 — UI flickering during task/subagent work
• #29271 — No distinction between idle-but-alive and dead teammates
• #25520 — Background agent permission prompts invisible
• #25539 — Status line stuck showing stale state

Those issues describe individual symptoms; this issue describes a broader progressive regression where the entire bottom bar rendering is unreliable, suggesting a systemic rendering or state management conflict — possibly between Agent Teams, plugins, hooks, statusLine, or some combination.

Impact

This is a significant observability regression for Agent Teams workflows. The TaskList is the primary mechanism for tracking teammate progress, blocked tasks, and completed work. Without it, the team lead is flying blind and must resort to manual TaskList tool calls or git status checks to understand what's happening.