Context Bar, a Claude Code context bar mod: see what fills your Claude Code context window

Context Bar is a community mod by Hamza Zafar (hamzafer), part of his claude-code-mods collection. It is a Claude Code context bar that answers one question: what is filling my context window? Above the Claude Code prompt it draws a small bordered band with a single stacked bar the width of the terminal. The bar is split into the same categories /context uses, such as system prompt, tools, MCP tools, memory files, skills and messages, followed by free space and the auto-compact buffer.

The header line reads like 48k of 200k · compacts at 167k with a colored percentage badge. The badge is green, turns yellow at 70% of the compaction point and red at 90% (measured against the full window when auto-compact is off). Under the bar, a legend lists each category with its token count and its share of the window, packed into as many lines as the terminal width needs. Tool schemas that are loaded on demand are left out, as /context leaves them out of its grid.

Context Bar is close to our own Context Meter, but they show different things. Context Meter is a single status-line string with the overall context percentage, the 5-hour and 7-day plan windows, the session cost and a one-time warning at 80%. Context Bar shows no plan usage or cost; instead it breaks the context down by category, so you can see whether MCP tools, memory files or the conversation itself is taking the space. The author's README needs Claude Code 2.1.287 or later.

The recording starts Claude Code with the mod loaded in the small demo project and asks Claude to read README.md and describe the project in one sentence. When the turn completes, the band above the prompt shows the context window split by category (system prompt, system tools, skills, messages, free space), the total such as 54k of 200k, where auto-compact kicks in, and the used percentage.

Use any of the methods in the install block; they install straight from the author's own marketplace. The bar appears on the next session start, and /context-bar hides or shows it.

The mod keeps the latest reading in a host-held $.state atom, so it survives a hot reload, and redraws it on the AbovePrompt render site. The refresh function, from hooks/register.tsx:

// Asks the engine for /context's breakdown, estimated locally (no token-count calls).
async function refresh($: EngineInterface) {
  if (await read($, isHidden)) return
  const usage = await $.session.usage({ breakdown: 'summary' })
  const b = usage.context.breakdown
  if (!b || !(b.rawMaxTokens > 0)) return // no window to measure against
  await update($, reading, () => toReading(b))
}

refresh runs on session.start, on turn.complete when there is no agentId (subagent turns are skipped), and on session.compact, because a /compact empties the window without a turn ending. toReading drops deferred categories and empty ones, sorts used rows before free space and the buffer, and assigns colors. Pure helpers cells and legend turn the reading into bar runs and legend lines: every used category gets at least one cell, and rounding leftovers go to free space first. Below 20 columns of inner width the bar is not drawn. When a survey is using the space above the prompt, the band steps aside.

There are no options in /config. The only switch is the /context-bar command, whose hidden/shown state is stored with $.store. To change the look, edit the constants at the top of register.tsx: PALETTE for the category colors, MESSAGES for the messages color, GLYPH for the bar characters and MIN_WIDTH for the narrowest width that still draws.

We read every file the plugin can execute before running it: hooks/hooks.json, hooks/register.tsx, the type declarations and the tests. There is no package.json, install script or bundled code.

Changes the UI covers the band above the prompt. Adds a command covers /context-bar. The mod reads context figures through $.session.usage, stores a single true/false value with $.store, and keeps its reading in $.state. It does not run shell commands, read or write files, use the network, read environment variables or call the model. claude plugin validate reported no errors or warnings, and the author's 6 tests passed on Claude Code 2.1.291.

Checked with Claude Code 2.1.291 on macOS (validate and tests). If the bar does not show up:

• claude --version is 2.1.287 or later.
• You did not hide it earlier: run /context-bar once and look for "Context bar on".
• The terminal is wide enough: the bar needs at least 24 columns for the band.
• A survey is open above the input; the band returns after it closes.
• The breakdown is only available once Claude Code knows the window size. If the band is missing at the very start, send one prompt.