Task tool allowlist missing Gemini 3.8 Flash (`gemini-3.8-flash`) after model launch

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Describe the Bug

Gemini 3.8 Flash is a first-class parent-agent model (model picker + docs), but the parent Task tool allowlist does not include it. The parent is also instructed not to substitute another model if the requested slug is missing, so asking for a Gemini 3.8 Flash subagent cannot launch.
This looks like a stale subagent allowlist after shipping Gemini 3.8 Flash. Older Gemini Flash IDs are still listed.

Steps to Reproduce

Actual Behavior

Task model enum for Gemini only allows:

  • gemini-3-flash
  • gemini-3.7-flash-high
    gemini-3.8-flash is absent. Parent system instructions: if the requested model is not in that list, do not substitute — skip launching and tell the user which models are available.

Screenshots / Screen Recordings

N/A (allowlist / tool schema, not visual)

Operating System

Windows 10 (build 26200)

Does this stop you from using Cursor?

No — but it blocks Gemini 3.8 Flash for subagent/orchestration workflows. Workaround is Gemini 3.7 Flash High, Gemini 3 Flash, or inherit if the parent is already 3.8 Flash.

Steps to Reproduce

  1. In Agent chat, ask the parent to launch a subagent on Gemini 3.8 Flash, e.g. “launch a 3.8 flash subagent to analyze this repo for bugs”.
  2. Observe that the parent refuses instead of calling Task with model: gemini-3.8-flash.

Expected Behavior

Expected Behavior

gemini-3.8-flash (and its effort/high variants, if those exist for chat) should be in the Task tool allowed model slugs, matching the chat picker and Models & Pricing | Cursor Docs / Gemini 3.8 Flash | Cursor Docs. The parent should be able to spawn explore/generalPurpose on Gemini 3.8 Flash.

Operating System

Windows 10/11

Version Information

Version Info
Cursor 3.19.7

Does this stop you from using Cursor

No - Cursor works, but with this issue

6

Same issue on Cursor 3.20.0 (macOS).

Calling Task with gemini-3.8-flash / gemini-3.8-flash-high still fails immediately:

Invalid model selection "…". Model could not be resolved to a valid subagent model.

Current allowed slugs (no Gemini at all):

  • claude-opus-5-thinking-high
  • composer-2.5-fast
  • cursor-grok-4.6-high
  • gpt-5.6-sol-xhigh

On 3.19.7 the Task enum still listed gemini-3-flash and gemini-3.7-flash-high. Those are gone now too, so the 3.7 workaround no longer works. Gemini 3.8 Flash is still selectable as a parent model (and in Settings → Explore Subagent Model), but it cannot be used as an explicit Task/subagent model.

7

@Palladin @fenx_w thanks, and your reads are both right. Gemini 3.8 Flash comes from a newer model registry than the older Gemini Flash models, and the Task tool’s local subagent list is still built from the older catalog, so registry models get dropped even though they show in the picker. On 3.20.0 the Gemini Task slugs dropped out entirely, which is why the 3.7 Flash High workaround no longer holds. This is on our side and we’re getting it filed.

The workaround that still holds: set your parent chat to Gemini 3.8 Flash and launch subagents with the model left as inherit or unset, so they run on the parent’s model instead of a pinned slug.

I’ll post here when the fix ships.

8

any update on this fix?

9

Just encountered the same issue. Any update on this? It’s crucial to be able to spawn subagents with the exact specified models.