Context Mode

The other half of the context problem.

The Problem

Every MCP tool call dumps raw data into your context window. A Playwright snapshot costs 56 KB. Twenty GitHub issues cost 59 KB. One access log — 45 KB. After 30 minutes, 40% of your context is gone. And when the agent compacts the conversation to free space, it forgets which files it was editing, what tasks are in progress, and what you last asked for. On top of that, the agent wastes output tokens on filler, pleasantries, and verbose explanations — burning context from both sides.

How Context Mode Solves It

Context Mode is an MCP server that solves all four sides of this problem:

1. Context Saving — Sandbox tools keep raw data out of the context window. 315 KB becomes 5.4 KB. 98% reduction.

2. Session Continuity — Every file edit, git operation, task, error, and user decision is tracked in SQLite. When the conversation compacts, context-mode doesn't dump this data back into context — it indexes events into FTS5 and retrieves only what's relevant via BM25 search. The model picks up exactly where you left off. If you don't --continue, previous session data is deleted immediately — a fresh session means a clean slate.

3. Think in Code — The LLM should program the analysis, not compute it. Instead of reading 50 files into context to count functions, the agent writes a script that does the counting and console.log()s only the result. One script replaces ten tool calls and saves 100x context. This is a mandatory paradigm across all 16 platforms: stop treating the LLM as a data processor, treat it as a code generator.

   // Before: 47 × Read() = 700 KB.  After: 1 × ctx_execute() = 3.6 KB.
   ctx_execute("javascript", `
     const files = fs.readdirSync('src').filter(f => f.endsWith('.ts'));
     files.forEach(f => console.log(f + ': ' + fs.readFileSync('src/'+f,'utf8').split('\\n').length + ' lines'));
   `);
   

4. No prose-style enforcement — context-mode keeps raw data out of context but never dictates how the model writes its final answer. Brevity, completeness, formatting — your model's call (or yours via your own CLAUDE.md / AGENTS.md). Aggressive brevity prompts have been shown to degrade coding/reasoning benchmarks (Moonshot AI on kimi-k2.5) — the routing block stays focused on where data goes, not on how the model talks.

Install

Platforms are grouped by install complexity. Hook-capable platforms get automatic routing enforcement. Non-hook platforms need a one-time routing file copy.

Prerequisites: Claude Code v1.0.33+ (claude --version). If /plugin is not recognized, update first: brew upgrade claude-code or npm update -g @anthropic-ai/claude-code.

Install:

/plugin marketplace add mksglu/context-mode
/plugin install context-mode@context-mode

Restart Claude Code (or run /reload-plugins).

Verify:

/context-mode:ctx-doctor

All checks should show [x]. The doctor validates runtimes, hooks, FTS5, and plugin registration.

Routing: Automatic. The SessionStart hook injects routing instructions at runtime — no file is written to your project. The plugin registers all hooks (PreToolUse, PostToolUse, PreCompact, SessionStart) and 11 MCP tools — six sandbox tools (ctx_batch_execute, ctx_execute, ctx_execute_file, ctx_index, ctx_search, ctx_fetch_and_index) plus five meta-tools (ctx_stats, ctx_doctor, ctx_upgrade, ctx_purge, ctx_insight).

| Slash Command | What it does | |---|---| | /context-mode:ctx-stats | Context savings — per-tool breakdown, tokens consumed, savings ratio. | | /context-mode:ctx-doctor | Diagnostics — runtimes, hooks, FTS5, plugin registration, versions. | | /context-mode:ctx-index | Index a local file or directory into the persistent FTS5 knowledge base. | | /context-mode:ctx-search | Search previously indexed content. | | /context-mode:ctx-upgrade | Pull latest, rebuild, migrate cache, fix hooks. | | /context-mode:ctx-purge | Permanently delete all indexed content from the knowledge base. | | /context-mode:ctx-insight | Personal analytics dashboard — 90 metrics, 37 insight patterns, 4 composite scores (productivity, quality, delegation, context health) across 23 event categories. Opens a local web UI. |

Note: Slash commands are a Claude Code plugin feature. On other platforms, type ctx stats, ctx doctor, ctx index, ctx search, ctx upgrade, or ctx insight in the chat — the model calls the MCP tool automatically. See Utility Commands.

Status line (optional): Claude Code's plugin manifest cannot declare a status line, so this is a one-time manual edit to ~/.claude/settings.json:

{
  "statusLine": {
    "type": "command",
    "command": "context-mode statusline"
  }
}

After saving, restart Claude Code. The bar shows $ saved this session · $ saved across sessions · % efficient so you can see savings accumulate in real time. The wiring is path-free — context-mode statusline resolves through the bundled CLI regardless of where the plugin cache lives.

claude mcp add context-mode -- npx -y context-mode

This gives you all 11 MCP tools without automatic routing. The model can still use them — it just won't be nudged to prefer them over raw Bash/Read/WebFetch. Good for trying it out before committing to the full plugin.

Prerequisites: Node.js >= 22.5 (or Bun),