Context Sidebar

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Provider-agnostic Context Usage sidebar for OpenCode TUI.

Features

• Latest assistant call token totals
• Input, cache hit, cache miss, and cache write breakdown
• Output, thinking, and response breakdown
• Cache hit rate and colored distribution bar
• Context-window usage with green, yellow, and red thresholds
• Session cumulative cost, matching OpenCode's built-in Context behavior
• Dynamic separators that follow the available sidebar width

The plugin works with any provider that reports standard OpenCode token usage fields.

Install

Install the package with OpenCode, then disable the built-in Context panel in ~/.config/opencode/tui.json or .opencode/tui.json:

{
  "$schema": "https://opencode.ai/tui.json",
  "plugin": ["opencode-context-sidebar"],
  "plugin_enabled": {
    "internal:sidebar-context": false
  }
}

Restart OpenCode after changing the configuration.

How It Works

The plugin uses data already normalized by OpenCode; it does not call provider APIs directly.

Provider response
  -> OpenCode normalizes token usage
  -> Plugin reads the latest assistant message
  -> Sidebar calculates and renders the breakdown

Display	OpenCode field	Meaning
Cache miss	tokens.input	Regular input not read from or written to cache
Cache hit	tokens.cache.read	Input reused from cache
Cache write	tokens.cache.write	Input written to cache for later requests
Response	tokens.output	Generated output excluding reasoning
Thinking	tokens.reasoning	Reasoning tokens reported by the model

The displayed totals are calculated as follows:

Input         = Cache miss + Cache hit + Cache write
Output        = Response + Thinking
Total         = Input + Output
Context usage = Total / model context limit * 100%

The context limit comes from the active model metadata. The displayed cost is OpenCode's cumulative session.cost, so provider-specific token pricing remains OpenCode's responsibility. Because the values are derived from the current session state, the sidebar updates as new assistant messages arrive.

Development

npm install
npm run build

For local loading:

{
  "$schema": "https://opencode.ai/tui.json",
  "plugin": ["file:///root/opencode-context-sidebar"],
  "plugin_enabled": {
    "internal:sidebar-context": false
  }
}

License

MIT