Allow customizing TUI status bar segments (model, cost, code changes, etc.) #40534

Feature request

The TUI status bar currently shows a fixed set of segments and is not user-configurable. It would be great to expose the status bar as a configurable surface so users can surface the info they care about at a glance.

What I'd like

A config field (e.g. statusbar / status_bar) in opencode.json that lets me pick which segments render and in what order, ideally with per-segment color. Useful segments:

• Current model (provider/model id)
• Per-session token cost ($$) and/or cumulative cost
• Code change summary (files changed / +/- lines since session start or vs base branch)
• Current agent + mode (build/plan/subagent)
• Git branch + dirty indicator
• Context window usage (tokens used / context limit)
• Session timer / message count

Why

A denser, color-coded status bar gives users real-time feedback on cost, context pressure, and the shape of their diff without leaving the conversation. Today this requires running separate commands or checking the diff manually.

Proposed shape (rough)

{
  "statusbar": {
    "segments": [
      { "type": "model", "color": "primary" },
      { "type": "cost", "color": "warning" },
      { "type": "diff", "color": "success" },
      { "type": "agent" },
      { "type": "git" },
      { "type": "context" }
    ]
  }
}

Each type maps to a built-in renderer. Unknown types ignored or warned. Colors reuse the existing theme palette (primary/secondary/accent/success/warning/error/info) plus hex.

Alternatives considered

• Hardcoding more segments upstream — works but forces one layout on everyone.
• Plugin hook that injects custom segments — more powerful but heavier; could be a follow-up.

Out of scope (for now)

• Custom user-defined segment renderers (TUI plugins). Worth considering as a later extension.