Design and surface subagent activity in the Atlas agent panel

[uzayer]

Problem

Atlas currently provides no user-facing subagent experience: users cannot see delegated tasks, their status, progress, outputs, or relationship to the parent agent.

This is intentionally a discovery/design-led issue. Use the interaction patterns in current Codex desktop/CLI, Claude Code desktop, and Zed’s parallel-agent/thread experiences for inspiration—adopt the useful principles, not a pixel-for-pixel clone.

Investigation

• The native Cersei agent already exposes a delegate tool and runs child tasks concurrently (with a depth cap), but Atlas’s chat model only renders generic tool calls.
• Claude session ingestion explicitly excludes internal agent-* files and isSidechain traffic, so subagent activity is intentionally invisible today.
• The current chat event/state model has no first-class child-agent/task entity, lifecycle, or view.
• Codex documents a useful baseline: active subagents are inspectable as individual threads, with their status and returned summary visible to the main chat. Zed likewise treats agent threads/parallel work as a first-class surface, while distinguishing native versus ACP/external-agent capabilities.

Scope

Define a cross-agent capability model, then implement the minimum end-to-end vertical slice for agents that can provide trustworthy child-task lifecycle data. The UI must clearly report when an external ACP agent does not expose subagent telemetry rather than pretending none exist.

Acceptance criteria

• A parent turn that delegates work exposes a compact subagent/task summary in the agent panel: task intent, agent identity/type when available, lifecycle status, elapsed time, and completion/failure state.
• Users can expand a task to inspect useful progress and the distilled result without flooding the parent conversation with raw child transcript noise.
• Where a child thread is available, users can open it in a dedicated inspectable view and return to the parent; controls for cancellation/stop are available only when the underlying agent supports them.
• The parent response makes the child results and their provenance clear.
• Capability gaps are explicit for Claude/Codex/other ACP integrations: “not reported by this agent” is distinct from “no subagents were used.”
• Concurrency, errors, cancellation, permission boundaries, token/cost attribution, persistence, and resumed/history sessions have an explicit product and data-model decision.
• Start with a documented interaction spec and instrumentation/event contract; add an implementation plan and tests for the initial Cersei delegate path before expanding to external agents.

References

• Codex multi-agent operations / current Codex product guidance.