Subagent panel stuck on "Starting up"; Stop All does nothing

Support Bug Reports
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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

After an Agent chat launched three Explore subagents during Plan mode research, the chat UI continued to show a “3 Working” panel with all three tasks stuck on “Starting up” for hours after the subagents had already completed successfully and returned results to the parent agent.

Clicking Stop All does not clear or cancel the stuck cards. The X/close control also fails to clear them in this session.

This is a UI/state persistence bug, not a hung worker:

  • Parent agent received full subagent results and continued (created a plan, then implemented it).
  • On-disk subagent transcripts all ended with turn_ended / status: success.
  • No active work remains for those three tasks.

Steps to Reproduce

  1. Start an Agent chat in Plan mode on a large workspace.
  2. Have the agent launch multiple Explore subagents in parallel (Task/Subagent tool), e.g. “Assess parser architecture”, “Inventory log variants”, “Map swap parser flow”.
  3. Wait until the parent agent continues and uses the subagent results (plan created / implementation proceeds).
  4. Observe the “N Working” panel still listing the subagents as “Starting up”.
  5. Click Stop All.
  6. Observe that the stuck cards remain.

Expected Behavior

  • Subagent cards should transition to Completed (or disappear) once transcripts end successfully.
  • Stop All should clear/cancel stuck working cards even if their UI status is desynced.
  • The Working panel should not claim active work after parent turn completion.

Actual:

  • Cards remain “Starting up” indefinitely (observed ~2 hours after completion).
  • Stop All has no effect.
  • Parent chat is otherwise usable.

Operating System

MacOS

Version Information

Version: 3.12.17
VSCode Version: 1.128.0
Commit: 0fb762053c34788bb7760d5673f8a6d4c8589d50
Date: 2026-07-17T02:53:53.006Z
OS: Darwin arm64 25.5.0

For AI issues: which model did you use?

Parent chat: Auto / Composer agent routing.
Subagents: Explore (subagent_type=explore) launched during Plan mode research.
run_in_background was false on launch; UI still desynced after completion.

For AI issues: add Request ID with privacy disabled

Parent conversation id: 2b16766c-ae5b-4ce0-8d6c-bd70627f90e0
Subagent ids (all turn_ended success ~16:12–16:14 local):

  • 572efe0c-e8ec-4419-8b3f-f68c0ca03607 — Assess parser architecture
  • 173b6460-0f83-447f-95c5-dd1a13acddb4 — Inventory log variants
  • 742520dc-f146-47b9-9b92-c0fae91755f9 — Map swap parser flow

Transcripts under:
~/.cursor/projects/Users-mizipkin-git-ScanAnalysis-WORKSPACE/agent-transcripts/2b16766c-ae5b-4ce0-8d6c-bd70627f90e0/subagents/

Additional Information

Related prior reports (marked fixed in 3.2.11, still present on 3.12.17):

  • forum topic 157718: sub-agents stuck at new subagent starting up
  • forum topic 158793: subagent callouts stuck in new subagent starting up in perpetuity
  • forum topic 158139: cursor blocked when new subagent

Additional regression: Stop All is a no-op for these desynced cards.

Temporary workaround: Cmd+Shift+P then Developer: Reload Window.

Does this stop you from using Cursor

No - Cursor works, but with this issue

6

+1 — I’m seeing the same lifecycle mismatch: background agent work reaches a terminal state, but task cards remain shown as active, and Stop All / window reload do not reliably clear them. Accurate terminal-state reconciliation and per-task cancellation would make async workflows much safer to use.

7

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Hello Cursor Support / Bug Reports team,

I’m reporting a recurring Multitask Mode / Agents Window UI bug in Cursor Desktop.

Summary

In Multitask Mode, the agent sidebar “Working” panel frequently shows background/subagent tasks stuck on “Starting up,” or lingering as orange “done” entries with file-edit summaries, long after the actual work has finished. Stop and Stop All often do nothing. The only reliable recovery is starting a new chat. This has happened more than once.

Environment

  • Product: Cursor Desktop
  • Feature: Multitask Mode / background agents panel (“Working,” e.g. “10 Working,” Stop All)
  • Date observed: 2026-07-23
  • OS: macOS (Darwin 25.5.0)
  • Workspace: local project (Ko3kr)

Expected behavior

  1. When a background/subagent finishes (success or clean exit), its entry should leave “Starting up” / active state and clear or mark complete in a dismissible way.
  2. Stop / Stop All should terminate running agents and dismiss or clear zombie task entries that are no longer running.
  3. Ideally, tasks that have already returned a final success response should auto-dismiss from the Working panel.

Actual behavior

  • Multiple task rows remain stuck on “Starting up” even though those agents completed successfully earlier the same day (artifacts produced, installs succeeded, OAuth/token work completed).
  • Other rows linger as orange “done” with edit summaries; Stop is visible but does not clear or stop them.
  • Stop All does not clear the panel.
  • Resuming/interrupting agents with explicit “confirm done and EXIT” prompts causes agents to exit cleanly on the agent side, but UI entries can still persist.
  • Only reliable workaround: open a new chat.

Stuck / zombie examples (same session / day)

Stuck showing “Starting up” long after successful completion:

  • “Install ReportLab + Playwright”
  • “Verify PDF library imports”
  • “Set up headless Sheets OAuth”
  • “Document Google Sheets integration”
  • “Document Firebase integration”

(These had already completed successfully earlier: docs written, packages installed, OAuth token + related sheet install OK.)

Lingering “done” / non-stoppable entries (Stop visible but ineffective):

  • scrape/rebuild work
  • throttled scrape
  • fix mod display
  • expand climb data visibility

Panel context: “10 Working” with Stop All available but ineffective.

Workarounds tried

  • Resume / interrupt stuck agents with “confirm done and EXIT” — agents exit cleanly; UI entries may still remain.
  • Stop / Stop All — often no effect.
  • New chat — only reliable fix.

Ask

  1. Please acknowledge stuck Multitask task entries that do not clear when agents finish.
  2. Please fix Stop / Stop All so they actually terminate or dismiss zombie tasks.
  3. Ideally auto-dismiss tasks that have already returned a final success response.

Happy to provide screenshots, Cursor version below.
Version: 3.12.30 (Universal)
VS Code Extension API: 1.128.0
Commit: 63a2996a10d9e476b6c28e951dd7691d9c0cf480
Date: 2026-07-21T22:50:03.568Z
Layout: Agent Window
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.256
OS: Darwin arm64 25.5.0

Thank you,
[Krister Laag]

Steps to Reproduce

Happens over and over again when using same chat for an extended period of time.

Expected Behavior

Old tasks should disappear. Should be able to press stop and it should disappear.

Screenshots / Screen Recordings

Screenshot 2026-07-24 at 14.11.04.png
Screenshot 2026-07-24 at 14.11.04.png738×351 35 KB

Operating System

MacOS

Version Information

Version: 3.12.30 (Universal)
VS Code Extension API: 1.128.0
Commit: 63a2996a10d9e476b6c28e951dd7691d9c0cf480
Date: 2026-07-21T22:50:03.568Z
Layout: Agent Window
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.256
OS: Darwin arm64 25.5.0

For AI issues: which model did you use?

Default Composer 2.5 Fast

Does this stop you from using Cursor

No - Cursor works, but with this issue