[FEATURE]: Toggleable top-bar status header — session title, context, cost, MCP/LSP status, git branch #25262

Feature hasn't been suggested before.

• Verified. (Related but narrower requests: [FEATURE]: Sticky editable session title row at top of TUI (click to rename or /rename) #24579 sticky title row, [FEATURE]: Better utilization of screen real estate #5419 screen real estate, [FEATURE]: Show session title in bottom/footer focus area #15344 footer title. None cover the full status panel in a non-occluding top-bar layout.)

The problem

The sidebar panel contains all session-at-a-glance info:

OpenCode JSON TUI session header visibility
Context
77,003 tokens · 39% used · $0.00 spent
MCP  blender ● · figma ✗ · gmail ● · google-calendar ● · notion ● · playwright ●
LSP  LSPs will activate as files are read
~/Documents/GitHub/ottomator/projects_ottomator/octo:master

This panel only appears when the terminal is wide enough to trigger the sidebar column. On a narrow window (split pane, laptop screen, vertical terminal layout) it disappears entirely — leaving no session context visible at all. There is no config or keybind to reposition it.

Proposed feature

A top-bar status header that renders the same session-context information as a fixed, non-occluding strip at the top of the chat area, above the scrolling message list.

Content (priority order)

1. Session title
2. Context token count + percentage used
3. Cost so far ($0.00 spent)
4. MCP server statuses (name + connected/disabled dot)
5. LSP status line
6. Git branch (~/path:branch)
7. (Modified files list — lowest priority / out of scope for v1)

Rendering requirements

• Non-occluding. The header must occupy real layout rows — it pushes the message list down rather than floating above it with a dimmed overlay. It should feel like a first-class layout element, the same way the input box at the bottom is part of the layout.
• Toggleable. A keybind (suggested: sidebar_toggle already exists as <leader>b — a new header_toggle or reusing sidebar_toggle when width is narrow) shows/hides the bar. The state persists across sessions (same mechanism as other managed TUI settings via ctrl+p).
• Not an overlay/modal. No background dimming. The message list remains fully readable and interactive behind/below it.
• Responsive. When the terminal is wide enough for the sidebar, the sidebar takes over and the top-bar can be hidden automatically (or kept — user preference). When narrow, the top-bar is the fallback.

Suggested tui.json surface

{
  "header": {
    "enabled": true,          // default: false (opt-in)
    "auto_hide_with_sidebar": true  // hides top-bar when sidebar is visible
  },
  "keybinds": {
    "header_toggle": "<leader>h"
  }
}

Sketch

┌─────────────────────────────────────────────────────────┐
│ Fix stuck webhooks · 77k tokens 39% · $0.00             │  ← top-bar row 1
│ MCP ● blender ● gmail ● notion  LSP ready  octo:master  │  ← top-bar row 2
├─────────────────────────────────────────────────────────┤
│                                                         │
│  [message list scrolls here]                            │
│                                                         │
├─────────────────────────────────────────────────────────┤
│  [input box]                                            │
└─────────────────────────────────────────────────────────┘

Why not the existing alternatives

Acceptance criteria

• Top-bar renders session title, token count/%, cost, MCP statuses, LSP line, git branch
• Top-bar is part of the layout (pushes message list down) — not a floating overlay
• Toggling with a keybind shows/hides it without dimming/greying the message area
• Toggle state persists (survives restart)
• tui.json opt-in flag controls default state
• Works independently of sidebar — both can be on, or either, or neither