Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
Summary
When a user configures Cursor Settings → Agents → Subagents → “Explore subagent model” to Composer 2.5, the parent (foreground) agent still launches background Task subagents with an explicit model: claude-4.6-opus-high-thinking parameter, ignoring the user’s subagent model preference.
Impact
With **Composer 2.5** configured under **Settings → Agents → Subagents**, the parent agent launched two parallel background subagents for delivery-loop work on issues **#116** and **#117**. Both ran as **Opus 4.6 High** instead of the configured subagent model. Running two expensive premium-model workers in parallel drove API usage to **100%** — a significant, unexpected cost/usage spike the user did not intend when they set subagents to Composer 2.5.
Steps to Reproduce
- Open Cursor Settings → Agents → Subagents
- Set “Explore subagent model” to Composer 2.5 (see screenshot below)
- In Multitask Mode, ask the parent agent to delegate work to background subagents (e.g. "run agent-delivery-loop for issue #116 and #117 in two subagents")
- Observe the parent agent launches Task subagents with
model: claude-4.6-opus-high-thinkingexplicitly set in the tool call
Expected behavior
- Background subagents should use the user’s configured subagent model (Composer 2.5) from Settings
- Parent agent should not override model selection unless the user explicitly requests a specific model in chat
- When no model is specified by the user, the Task tool should inherit/respect Settings → Agents → Subagents rather than the parent agent picking the strongest available model
Actual behavior
- Parent agent autonomously selects
claude-4.6-opus-high-thinkingforgeneralPurposeTask subagents - User’s Composer 2.5 subagent setting is ignored
- User pays higher cost / different latency than configured
Screenshots / Screen Recordings
Operating System
MacOS
Version Information
| Field | Value |
|---|---|
| OS | darwin 25.5.0 (macOS) |
| Subagent setting | Explore subagent model → Composer 2.5 |
| Mode | Multitask Mode |
| Tool | Task with subagent_type: generalPurpose |
| Issue | Parent passes explicit model param |
For AI issues: add Request ID with privacy disabled
4f623943-4bed-4e0c-b51a-60f32cf66114
Additional Information
This is recurring, not a one-off: with Composer 2.5 configured under Settings → Agents → Subagents, parallel background subagents spawned via the Task tool have repeatedly included an explicit model field even though the user did not request a specific model in chat. Observed overrides include Opus 4.6 (claude-4.6-opus-high-thinking) and Opus 4.8 (claude-opus-4-8-thinking-high or similar).
Does this stop you from using Cursor
No - Cursor works, but with this issue
