[FEATURE] subagentStatusLine: support refreshInterval, or keep elapsed time and tokens live in custom rows

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

subagentStatusLine replaces the whole row body of each subagent in the agent panel, including the elapsed time and token count. The command is re-run on a fixed 5-second timer, and its output is a static string until the next run.

So a custom row that keeps the default layout (<type> <label> 20m 37s · ↓ 238.2k tokens) and only adds one piece of information, such as the model, makes the elapsed time jump in 5-second steps. The default row updates every second. Adding one field costs you the live timer.

Unlike statusLine, subagentStatusLine does not accept refreshInterval. The schema only takes type and command, and the timer is hardcoded (kVe=5000 in 2.1.299).

Proposed Solution

Either of these would solve it:

1. Support refreshInterval in subagentStatusLine, the same way statusLine does (minimum 1).
2. Let the script customize only part of the row. For example, Claude Code keeps rendering the elapsed time and token count itself (live), and the script's content replaces only the name · description part. This could be opt-in through an output field such as {"id": "...", "content": "...", "keepStats": true}.

Option 2 is better: the stats stay live without running the script every second.

Alternative Solutions

• Show the subagent's model in the default row (#90246). That would cover my use case without any script.
• Drop seconds from the custom row so the 5-second lag isn't visible. That is a workaround, not a fix.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

I run several subagents in parallel on different models (Haiku 5.5, Sonnet 5.5, Opus 5.5) and want each row to show the model and effort:

general-purpose  Haiku 5.5 (low)     Committing payouts calc and web changes   20m 37s · ↓ 238.2k tokens
Explore          Opus 5.5 (medium)   Wiring closing prices into nova-operacao   7m 43s · ↓ 45.1k tokens

With subagentStatusLine this works, but the timer only moves every 5 seconds, while the default rows move every second.

Additional Context

• Claude Code 2.1.299 (macOS) and 2.1.300 (Linux)
• Related: #90246 (model in the default agent row), #97634 (no place in the UI shows a subagent's model)

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_This issue was written with Claude Opus 5.5 via Claude Code._