Is_background: true not working in nested subagents (level 2+)

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

When is_background: true is set on subagent definitions, background dispatch works correctly at level 1 but not at level 2+.

At level 1 (main agent dispatching subagents): Works as expected — dispatches a batch of 4 subagents, reports them running in background, and immediately continues to dispatch the next batch.

At level 2 (subagent dispatching nested subagents): Dispatches 4 subagents but blocks until the entire batch completes before moving to the next one. No “running in background” message appears. The is_background setting is effectively ignored.

This may be related to ** Nested subagents don't inherit model in MAX mode** , where level 2+ subagents fall back to composer1.5 instead of inheriting the configured model. If nested subagents are silently downgraded to composer1.5, that model may not support background execution — which would explain why is_background stops working at the same nesting level.

Steps to Reproduce

  1. Enable MAX mode with claude-4.6-opus-max
  2. Set is_background: true on all subagent .md files
  3. Have the main agent dispatch subagents in parallel (level 1) — works correctly
  4. Have those subagents dispatch their own nested subagents (level 2) — blocks, no background behavior

Expected Behavior

is_background: true should work at all subagent nesting levels, not just level 1.

Operating System

Windows 10/11

Version Information

Version: 2.6.12 (user setup)
VSCode Version: 1.105.1
Commit: 1917e900a0c4b0111dc7975777cfff60853059d0
Date: 2026-03-04T21:41:18.914Z
Build Type: Stable
Release Track: Default
Electron: 39.6.0
Chromium: 142.0.7444.265
Node.js: 22.22.0
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.22631

For AI issues: which model did you use?

claude-4.6-opus-max-thinking,
claude-4.6-opus-high,
gpt-5.4-medium-thinking’
All with MAX mode enabled

For AI issues: add Request ID with privacy disabled

Request ID: 6e2b3283-fb94-456e-90ca-8cd95f4803c7
Privacy Mode is enabled and controlled by our org admin. It can’t be turned off.

Does this stop you from using Cursor

No - Cursor works, but with this issue

3

Hey, thanks for the report, and I remember the previous thread about model inheritance.

Your hypothesis sounds plausible. The basic is_background: true fix landed in 2.6, but it looks like it only covers level 1. If level 2+ sub-agents are still falling back to composer1.5 due to the model inheritance bug you already reported, that could explain why background execution breaks specifically at that level.

I passed this to the team. It’s basically a continuation of the same propagation issue at nested levels.

Let me know if anything changes on your side.