Feature request: render referenced Codex threads and subagents as clickable chips in agent output

Feature request

When Codex agent output references another Codex thread, subagent, or thread/subagent id, render that reference as a clickable chip instead of plain static text or a raw id whenever possible.

Problem

In inline thread and agent thinking outputs, references to subagents or Codex threads can currently appear as plain names or raw ids. That makes it harder to tell whether the reference is actionable, what kind of object it points to, and whether it can be opened directly.

This is especially noticeable when an agent mentions something like a reviewer subagent, background thread, or copied thread id inside a status update or final summary. The user has to visually parse the text and may not realize there is a linked entity behind it.

Proposed behavior

When the renderer or message composer can identify a referenced Codex thread or subagent:

• Replace the raw id/static text reference with a clickable inline chip.
• Include an icon that distinguishes the entity type, such as thread vs. subagent.
• Include a readable label, such as the subagent name or thread title/name when available.
• Preserve the id in tooltip, accessible label, copy action, or chip metadata so the raw identifier remains recoverable.
• Make the chip open/navigate to the referenced thread or subagent detail view where supported.

Example display shape:

Reviewed by [icon] reviewer-agent
Continued in [icon] Thread: packaging follow-up

instead of:

Reviewed by subagent abc123...
Continued in thread 01HX...

Acceptance criteria

• References to known Codex thread ids in agent-authored output render as clickable thread chips when the target can be resolved.
• References to known subagents render as clickable subagent chips when the target can be resolved.
• Unresolvable or stale references gracefully remain readable text, without breaking the message.
• The chip has accessible text that identifies the target type and display name/id.
• Users can still inspect or copy the underlying id when needed.

Notes

This would make multi-agent work and cross-thread handoffs easier to scan, especially in inline thinking/status outputs and closeout summaries.