Context Mode is an MCP server that solves all three 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 12 platforms: stop treating the LLM as a data processor, treat it as a code generator.

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 6 sandbox tools (ctx_batch_execute, ctx_execute, ctx_execute_file, ctx_index, ctx_search, ctx_fetch_and_index) plus 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-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 — 15+ metrics on tool usage, session activity, error rate, parallel work patterns, and mastery curve. Opens a local web UI. |

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

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

This gives you the 6 sandbox 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 18+, Gemini CLI installed.

Install:

1. Install context-mode globally:

   npm install -g context-mode
   

2. Add the following to ~/.gemini/settings.json. This single file registers the MCP server and all four hooks:

   {
     "mcpServers": {
       "context-mode": {
         "command": "context-mode"
       }
     },
     "hooks": {
       "BeforeTool": [
         {
           "matcher": "run_shell_command|read_file|read_many_files|grep_search|search_file_content|web_fetch|activate_skill|mcp__plugin_context-mode",
           "hooks": [{ "type": "command", "command": "context-mode hook gemini-cli beforetool" }]
         }
       ],
       "AfterTool": [
         {
           "matcher": "",
           "hooks": [{ "type": "command", "command": "context-mode hook gemini-cli aftertool" }]
         }
       ],
       "PreCompress": [
         {
           "matcher": "",
           "hooks": [{ "type": "command", "command": "context-mode hook gemini-cli precompress" }]
         }
       ],
       "SessionStart": [
         {
           "matcher": "",
           "hooks": [{ "type": "command", "command": "context-mode hook gemini-cli sessionstart" }]
         }
       ]
     }
   }
   

3. Restart Gemini CLI.

Verify:

/mcp list

You should see context-mode: ... - Connected.

Routing: Automatic. The SessionStart hook injects routing instructions at runtime — no GEMINI.md file is written to your project. All four hooks (BeforeTool, AfterTool, PreCompress, SessionStart) handle enforcement programmatically.

Why the BeforeTool matcher? It targets only tools that produce large output (run_shell_command, read_file, read_many_files, grep_search, search_file_content, web_fetch, activate_skill)