[Feature]: Grok 4.6 subagent support in the Agents panel

[adinvadim]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area

apps/server

Problem or use case

Grok 4.6 is the current Grok CLI default and regularly spawns in-process subagents (spawn_subagent, plus _x.ai/session/update subagent_spawned / subagent_finished).

In T3 those children do not show up in the Agents panel. The parent turn only gets a fat spawn_subagent tool row. Child-session updates are still dropped (V1 choice from #3156).

I hit this daily as a grok-4.6 user.

Proposed solution

Map Grok's subagent lifecycle onto the existing task.started / task.completed path Claude and Codex already use for the Agents panel. Keep child transcripts out of the parent timeline.

Why this matters

Multi-agent grok-4.6 turns are common and currently invisible next to Claude/Codex.

Smallest useful scope

Grok adapter only:

• emit task.* from subagent_spawned / subagent_finished
• hide the bulky spawn_subagent tool row
• no nested-thread UX, no child-transcript merge

Alternatives considered

#5420 is the earlier task-mapping request. #6410 is an open PR in this direction. This is the grok-4.6-scoped request I can take if that work does not land.

#538 (nested threads) is a larger follow-up.

Risks or tradeoffs

Need unique event stamps, per-taskId dedupe, and a name-based detector so unrelated tools are not treated as subagents.

Examples or references

• Grok CLI 1.0.3: grok-4.6 (default), grok-4.5
• Related: Grok provider: multi-agent visibility via task.* events #5420, feat(server): show Grok subagents in the Agents panel #6410, fix(grok): Harden ACP resume with replay-idle load readiness #3156, Subagent support as nested threads #538

Contribution

• I would be open to helping implement this.

I use grok-4.6 every day and I am ready to implement this if the scope above looks right.