pk-context-mode

v1.0.90

Published

21 days ago

MCP plugin that saves 98% of your context window. Works with Claude Code, Gemini CLI, VS Code Copilot, OpenCode, and Codex CLI. Sandboxed code execution, FTS5 knowledge base, and intent-driven search.

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pk-nerdsaver-ai

mcp model-context-protocol claude claude-code gemini-cli vscode-copilot opencode openclaw codex-cli context-window sandbox code-execution fts5 bm25

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.

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

Context Saving — Sandbox tools keep large raw outputs out of the context window. In the benchmark fixture set, 315 KB becomes 5.5 KB for structured-output scenarios (98% reduction).
Session Continuity — On hook-capable platforms, file edits, git operations, tasks, errors, and user decisions are tracked in SQLite. When the conversation compacts, context-mode indexes events into FTS5 and retrieves relevant state via BM25 search. Coverage varies by platform; MCP-only and partial-hook clients still get the sandbox tools but not full restore.
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 can save 100x context on large outputs. This pattern is available wherever the MCP tools are installed.

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 pk-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:

Install context-mode globally:
```
npm install -g pk-context-mode
```

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" }]
      }
    ]
  }
}

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) plus context-mode's own tools (mcp__plugin_context-mode). This avoids unnecessary hook overhead on lightweight tools while intercepting every tool that could flood your context window.

Full config reference: configs/gemini-cli/settings.json

Prerequisites: Node.js 18+, VS Code with Copilot Chat v0.32+.

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```

Create .vscode/mcp.json in your project root:

{
  "servers": {
    "context-mode": {
      "command": "context-mode"
    }
  }
}

Create .github/hooks/context-mode.json:

{
  "hooks": {
    "PreToolUse": [
      { "type": "command", "command": "context-mode hook vscode-copilot pretooluse" }
    ],
    "PostToolUse": [
      { "type": "command", "command": "context-mode hook vscode-copilot posttooluse" }
    ],
    "SessionStart": [
      { "type": "command", "command": "context-mode hook vscode-copilot sessionstart" }
    ]
  }
}

Restart VS Code.

Verify: Open Copilot Chat and type ctx stats. Context-mode tools should appear and respond.

Routing: Automatic. The SessionStart hook injects routing instructions at runtime — no copilot-instructions.md file is written to your project.

Full hook config including PreCompact: configs/vscode-copilot/hooks.json

Prerequisites: Node.js 18+, Cursor with agent mode.

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```

Create .cursor/mcp.json in your project root (or ~/.cursor/mcp.json for global):

{
  "mcpServers": {
    "context-mode": {
      "command": "context-mode"
    }
  }
}

Create .cursor/hooks.json (or ~/.cursor/hooks.json for global):

{
  "version": 1,
  "hooks": {
    "preToolUse": [
      {
        "command": "context-mode hook cursor pretooluse",
        "matcher": "Shell|Read|Grep|WebFetch|Task|MCP:ctx_execute|MCP:ctx_execute_file|MCP:ctx_batch_execute"
      }
    ],
    "postToolUse": [
      {
        "command": "context-mode hook cursor posttooluse"
      }
    ],
    "stop": [
      {
        "command": "context-mode hook cursor stop"
      }
    ]
  }
}

The preToolUse matcher is optional — without it, the hook fires on all tools. The stop hook fires when the agent turn ends and can send a followup message to continue the loop. afterAgentResponse is also available (fire-and-forget, receives full response text).

Copy the routing rules file. Cursor lacks a SessionStart hook, so the model needs a rules file for routing awareness:
```
mkdir -p .cursor/rules
cp node_modules/context-mode/configs/cursor/context-mode.mdc .cursor/rules/context-mode.mdc
```
Restart Cursor or open a new agent session.

Verify: Open Cursor Settings > MCP and confirm "context-mode" shows as connected. In agent chat, type ctx stats.

Routing: Hooks enforce routing programmatically via preToolUse/postToolUse/stop. The .cursor/rules/context-mode.mdc file provides routing instructions at session start since Cursor's sessionStart hook is currently rejected by their validator (forum report). Project .cursor/hooks.json overrides ~/.cursor/hooks.json.

Known limitation: Cursor accepts additional_context in hook responses but does not surface it to the model (forum #155689). Routing relies on the .mdc rules file instead of hook context injection.

Full configs: configs/cursor/hooks.json | configs/cursor/mcp.json | configs/cursor/context-mode.mdc

Prerequisites: Node.js 18+, OpenCode installed.

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```
Add to opencode.json in your project root (or ~/.config/opencode/opencode.json for global):
```
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "context-mode": {
      "type": "local",
      "command": ["context-mode"]
    }
  },
  "plugin": ["context-mode"]
}
```
The mcp entry registers the 6 sandbox tools. The plugin entry enables hooks — OpenCode calls the plugin's TypeScript functions directly before and after each tool execution, blocking dangerous commands and enforcing sandbox routing.
(Optional) Copy the routing rules file. OpenCode lacks a SessionStart hook, so the model needs an AGENTS.md file for routing awareness:
```
cp node_modules/context-mode/configs/opencode/AGENTS.md AGENTS.md
```
This tells the model which tools to use and which commands are blocked. Without it, hooks still enforce routing — but the model won't know why a command was denied.
Restart OpenCode.

Verify: In the OpenCode session, type ctx stats. Context-mode tools should appear and respond.

Routing: Hooks enforce routing programmatically via tool.execute.before and tool.execute.after. The optional AGENTS.md file provides routing instructions for model awareness. The experimental.session.compacting hook builds resume snapshots when the conversation compacts.

Note: OpenCode's SessionStart hook is not yet available (#14808), so startup/resume session restore is not supported. Compaction recovery works fully via the plugin.

Full configs: configs/opencode/opencode.json | configs/opencode/AGENTS.md

Prerequisites: Node.js 18+, KiloCode installed.

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```
Add to kilo.json in your project root (or ~/.config/kilo/kilo.json for global):
```
{
  "$schema": "https://app.kilo.ai/config.json",
  "mcp": {
    "context-mode": {
      "type": "local",
      "command": ["context-mode"]
    }
  },
  "plugin": ["context-mode"]
}
```
The mcp entry registers the 6 sandbox tools. The plugin entry enables hooks — KiloCode calls the plugin's TypeScript functions directly before and after each tool execution, blocking dangerous commands and enforcing sandbox routing.
(Optional) Copy the routing rules file. KiloCode shares the OpenCode plugin architecture and lacks SessionStart, so the model needs an AGENTS.md file for routing awareness:
```
cp node_modules/context-mode/configs/opencode/AGENTS.md AGENTS.md
```
Restart KiloCode.

Verify: In the KiloCode session, type ctx stats. Context-mode tools should appear and respond.

Note: KiloCode shares the same plugin architecture as OpenCode, using the OpenCodeAdapter with platform-specific configuration paths (kilo.json instead of opencode.json, ~/.config/kilo/ instead of ~/.config/opencode/). SessionStart hook availability depends on KiloCode's implementation.

Prerequisites: OpenClaw gateway running (>2026.1.29), Node.js 22+.

context-mode runs as a native OpenClaw gateway plugin, targeting Pi Agent sessions (Read/Write/Edit/Bash tools). Unlike other platforms, there's no separate MCP server — the plugin registers directly into the gateway runtime via OpenClaw's plugin API.

Install:

Clone and install:
```
git clone https://github.com/mksglu/context-mode.git
cd context-mode
npm run install:openclaw
```
The installer uses $OPENCLAW_STATE_DIR from your environment (default: /openclaw). To specify a custom path:
```
npm run install:openclaw -- /path/to/openclaw-state
```
Common locations: Docker — /openclaw (the default). Local — ~/.openclaw or wherever you set OPENCLAW_STATE_DIR.
The installer handles everything: npm install, npm run build, better-sqlite3 native rebuild, extension registration in runtime.json, and gateway restart via SIGUSR1.
Open a Pi Agent session.

Verify: The plugin registers 8 hooks via api.on() (lifecycle) and api.registerHook() (commands). Type ctx stats to confirm tools are loaded.

Routing: Automatic. All tool interception, session tracking, and compaction recovery hooks activate automatically — no manual hook configuration or routing file needed.

Minimum version: OpenClaw >2026.1.29 — this includes the api.on() lifecycle fix from PR #9761. On older versions, lifecycle hooks silently fail. The adapter falls back to DB snapshot reconstruction (less precise but preserves critical state).

Full documentation: docs/adapters/openclaw.md

Prerequisites: Node.js 18+, Codex CLI installed.

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```

Add to ~/.codex/config.toml:

[mcp_servers.context-mode]
command = "context-mode"

(Waiting for upstream) Enable the hooks feature flag. Add to ~/.codex/config.toml:
```
[features]
codex_hooks = true
```
Status: Codex CLI's hook system is implemented in source (codex-rs/hooks/) but hook dispatch is not yet wired into the tool execution pipeline (Stage::UnderDevelopment). The feature flag is accepted but hooks don't fire during sessions as of v0.118.0. Our hook scripts are ready — they'll work immediately once Codex enables dispatch. Track progress: openai/codex#16685.
(Prepare for when dispatch is enabled) Add hooks for routing enforcement and session tracking. Create ~/.codex/hooks.json:
```
{
  "hooks": {
    "PreToolUse": [{ "hooks": [{ "type": "command", "command": "context-mode hook codex pretooluse" }] }],
    "PostToolUse": [{ "hooks": [{ "type": "command", "command": "context-mode hook codex posttooluse" }] }],
    "SessionStart": [{ "hooks": [{ "type": "command", "command": "context-mode hook codex sessionstart" }] }]
  }
}
```
PreToolUse enforces sandbox routing (blocks dangerous commands, redirects to MCP tools). PostToolUse captures session events. SessionStart restores state after compaction.
Note: PreToolUse routing supports deny rules only (blocks dangerous commands). Context injection (additionalContext) is not supported in Codex PreToolUse — it works via PostToolUse and SessionStart instead. This is handled automatically.
Copy routing instructions (recommended even with hooks for full routing awareness):
```
cp node_modules/context-mode/configs/codex/AGENTS.md ./AGENTS.md
```
For global use: cp node_modules/context-mode/configs/codex/AGENTS.md ~/.codex/AGENTS.md. Global applies to all projects. If both exist, Codex CLI merges them.
Restart Codex CLI.

Verify: Start a session and type ctx stats. Context-mode tools should appear and respond.

Routing: MCP tools work. Hook-based routing is ready but waiting for Codex to enable hook dispatch. The AGENTS.md file provides routing instructions for model awareness in the meantime.

Exec mode regression (v0.118.0): codex exec cancels all MCP tool calls with "user cancelled MCP tool call". The tool_call_mcp_elicitation flag went stable in 0.118.0, adding an approval prompt that exec-mode can't handle. Pin to Codex ≤0.116.0 for exec-mode MCP. Confirmed by upstream: openai/codex#16685. Interactive mode (codex / codex --full-auto) is not affected.

Prerequisites: Node.js 18+, Antigravity installed.

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```

Add to ~/.gemini/antigravity/mcp_config.json:

{
  "mcpServers": {
    "context-mode": {
      "command": "context-mode"
    }
  }
}

Copy routing instructions (Antigravity has no hook support):

cp node_modules/context-mode/configs/antigravity/GEMINI.md ./GEMINI.md

Restart Antigravity.

Verify: In an Antigravity session, type ctx stats. Context-mode tools should appear and respond.

Routing: Manual. The GEMINI.md file is the only enforcement method (~60% compliance). There is no programmatic interception. Auto-detected via MCP protocol handshake (clientInfo.name) — no manual platform configuration needed.

Full configs: configs/antigravity/mcp_config.json | configs/antigravity/GEMINI.md

Prerequisites: Node.js 18+, Kiro with MCP enabled (Settings > search "MCP").

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```

Add to .kiro/settings/mcp.json in your project (or ~/.kiro/settings/mcp.json for global):

{
  "mcpServers": {
    "context-mode": {
      "command": "context-mode"
    }
  }
}

Create .kiro/hooks/context-mode.json:

{
  "name": "context-mode",
  "description": "Context-mode hooks for context window protection",
  "hooks": {
    "preToolUse": [
      { "matcher": "*", "command": "context-mode hook kiro pretooluse" }
    ],
    "postToolUse": [
      { "matcher": "*", "command": "context-mode hook kiro posttooluse" }
    ]
  }
}

Copy routing instructions. Kiro's agentSpawn (SessionStart) is not yet implemented, so the model needs a routing file at session start:
```
cp node_modules/context-mode/configs/kiro/KIRO.md ./KIRO.md
```
Restart Kiro.

Verify: Open the Kiro panel > MCP Servers tab and confirm "context-mode" shows a green status indicator. In chat, type ctx stats.

Routing: Hooks enforce routing programmatically via preToolUse/postToolUse. The KIRO.md file provides routing instructions since agentSpawn (SessionStart equivalent) is not yet wired. Tool names appear as @context-mode/ctx_batch_execute, @context-mode/ctx_search, etc. Auto-detected via MCP protocol handshake.

Full configs: configs/kiro/mcp.json | configs/kiro/agent.json | configs/kiro/KIRO.md

Prerequisites: Node.js 18+, Zed installed.

Install:

Install context-mode globally:
```
npm install -g pk-context-mode
```
Add to ~/.config/zed/settings.json (Windows: %APPDATA%\Zed\settings.json):
```
{
  "context_servers": {
    "context-mode": {
      "command": {
        "path": "context-mode"
      }
    }
  }
}
```
Note: Zed uses "context_servers" and "command": { "path": "..." } syntax, not "mcpServers" or "command": "..." like other platforms.

Copy routing instructions (Zed has no hook support):

cp node_modules/context-mode/configs/zed/AGENTS.md ./AGENTS.md

Restart Zed (or save settings.json — Zed auto-restarts context servers on config change).

Verify: Open the Agent Panel (Cmd+Shift+A), go to settings, and check the indicator dot next to "context-mode" — green means active. Type ctx stats in the agent chat.

Routing: Manual. The AGENTS.md file is the only enforcement method (~60% compliance). There is no programmatic interception. Tool names appear as mcp:context-mode:ctx_batch_execute, mcp:context-mode:ctx_search, etc. Auto-detected via MCP protocol handshake.

Prerequisites: Node.js 18+, Pi Coding Agent installed.

Install:

Clone the extension:

git clone https://github.com/mksglu/context-mode.git ~/.pi/extensions/context-mode
cd ~/.pi/extensions/context-mode
npm install
npm run build

Add to ~/.pi/agent/mcp.json (or .pi/mcp.json for project-level):

{
  "mcpServers": {
    "context-mode": {
      "command": "node",
      "args": ["/home/youruser/.pi/extensions/context-mode/node_modules/context-mode/start.mjs"]
    }
  }
}

Note: JSON does not expand ~. Replace /home/youruser with your actual home directory (run echo $HOME to find it).

Restart Pi.

Verify: In a Pi session, type ctx stats. Context-mode tools should appear and respond.

Routing: Automatic. The extension registers all key lifecycle events (tool_call, tool_result, session_start, session_before_compact), providing full session continuity and routing enforcement.

Context Mode uses better-sqlite3 on Node.js, which ships prebuilt native binaries for most platforms. On glibc >= 2.31 systems (Ubuntu 20.04+, Debian 11+, Fedora 34+, macOS, Windows), npm install works without any build tools.

Linux + Node.js >= 22.13: Context Mode automatically uses the built-in node:sqlite module instead of better-sqlite3. This eliminates the native addon entirely, avoiding sporadic SIGSEGV crashes caused by V8's madvise(MADV_DONTNEED) corrupting the addon's .got.plt section on Linux. No configuration needed — detection is automatic. Falls back to better-sqlite3 on older Node.js versions.

Bun users: No native compilation needed. Context Mode automatically detects Bun and uses the built-in bun:sqlite module via a compatibility adapter. better-sqlite3 and all its build dependencies are skipped entirely.

On older glibc systems (CentOS 7/8, RHEL 8, Debian 10), prebuilt binaries don't load and better-sqlite3 automatically falls back to compiling from source via prebuild-install || node-gyp rebuild --release. This requires a C++20 compiler (GCC 10+), Make, and Python with setuptools.

CentOS 8 / RHEL 8 (glibc 2.28):

dnf install -y gcc-toolset-10-gcc gcc-toolset-10-gcc-c++ make python3 python3-setuptools
scl enable gcc-toolset-10 'npm install -g pk-context-mode'

CentOS 7 / RHEL 7 (glibc 2.17):

yum install -y centos-release-scl
yum install -y devtoolset-10-gcc devtoolset-10-gcc-c++ make python3
pip3 install setuptools
scl enable devtoolset-10 'npm install -g pk-context-mode'

Alpine Linux:

Alpine prebuilt binaries (musl) are available in better-sqlite3 v12.8.0+. With the ^12.6.2 dependency range, npm install resolves to the latest 12.x and works without build tools on Alpine. If you pin an older version:

apk add build-base python3 py3-setuptools
npm install -g pk-context-mode

Tools

| Tool | What it does | Context saved | |---|---|---| | ctx_batch_execute | Run multiple commands + search multiple queries in ONE call. | Large command output → targeted search results | | ctx_execute | Run code in 11 languages. Only stdout enters context. | 56 KB → 299 B | | ctx_execute_file | Process files in sandbox. Raw content never leaves. | 45 KB → 155 B | | ctx_index | Chunk markdown into FTS5 with BM25 ranking. | Raw source → indexed pointer + on-demand results | | ctx_search | Query indexed content with multiple queries in one call. | On-demand retrieval | | ctx_fetch_and_index | Fetch URL, chunk and index. 24h TTL cache — repeat calls skip network. force: true to bypass. | Fresh fetch returns a short preview; cached fetch returns a pointer | | ctx_stats | Show context savings, call counts, and session statistics. | — | | ctx_doctor | Diagnose installation: runtimes, hooks, FTS5, versions. | — | | ctx_upgrade | Upgrade to latest version from GitHub, rebuild, reconfigure hooks. | — | | ctx_purge | Permanently deletes all indexed content from the knowledge base. | — |

How the Sandbox Works

Each ctx_execute call spawns an isolated subprocess with its own process boundary. Scripts can't access each other's memory or state. The subprocess runs your code, captures stdout, and only that stdout enters the conversation context. The raw data — log files, API responses, snapshots — never leaves the sandbox.

Eleven language runtimes are available: JavaScript, TypeScript, Python, Shell, Ruby, Go, Rust, PHP, Perl, R, and Elixir. Bun is auto-detected for 3-5x faster JS/TS execution.

Authenticated CLIs work through credential passthrough — gh, aws, gcloud, kubectl, docker inherit environment variables and config paths without exposing them to the conversation.

When output exceeds 5 KB and an intent is provided, Context Mode switches to intent-driven filtering: it indexes the full output into the knowledge base, searches for sections matching your intent, and returns only the relevant matches with a vocabulary of searchable terms for follow-up queries.

How the Knowledge Base Works

The ctx_index tool chunks markdown content by headings while keeping code blocks intact, then stores them in a SQLite FTS5 (Full-Text Search 5) virtual table. The SQLite backend is selected automatically at runtime: bun:sqlite on Bun, node:sqlite on Linux + Node.js >= 22.13, and better-sqlite3 everywhere else. Search uses BM25 ranking — a probabilistic relevance algorithm that scores documents based on term frequency, inverse document frequency, and document length normalization. Porter stemming is applied at index time so "running", "runs", and "ran" match the same stem. Titles and headings are weighted 5x in BM25 scoring for precise navigational queries.

When you call ctx_search, it returns relevant content snippets focused around matching query terms — not full documents, not approximations, the actual indexed content with smart extraction around what you're looking for. ctx_fetch_and_index extends this to URLs: fetch, convert HTML to markdown, chunk, index. The raw page never enters context. Use the contentType parameter to filter results by type (e.g. code or prose).

Ranking: Reciprocal Rank Fusion

Search runs two parallel strategies and merges them with Reciprocal Rank Fusion (RRF):

Porter stemming — FTS5 MATCH with porter tokenizer. "caching" matches "cached", "caches", "cach".
Trigram substring — FTS5 trigram tokenizer matches partial strings. "useEff" finds "useEffect", "authenticat" finds "authentication".

RRF merges both ranked lists into a single result set, so a document that ranks well in both strategies surfaces higher than one that ranks well in only one. This replaces the old cascading fallback approach where trigram results were only used if porter returned nothing.

Proximity Reranking

Multi-term queries get an additional reranking pass. Results where query terms appear close together are boosted — "session continuity" ranks passages with adjacent terms higher than pages where "session" and "continuity" appear paragraphs apart.

Fuzzy Correction

Levenshtein distance corrects typos before re-searching. "kuberntes" becomes "kubernetes", "autentication" becomes "authentication".

Smart Snippets

Search results use intelligent extraction instead of truncation. Instead of returning the first N characters (which might miss the important part), Context Mode finds where your query terms appear in the content and returns windows around those matches.

TTL Cache

Indexed content persists in a per-project SQLite database under the detected platform's context-mode directory, such as ~/.claude/context-mode/content/, ~/.cursor/context-mode/content/, or another adapter-specific equivalent. Older ~/.context-mode/content/ stores are treated as legacy cleanup targets. When ctx_fetch_and_index is called for a URL that was already indexed within the last 24 hours, the fetch is skipped entirely. The model searches the existing index directly.

Fresh (<24h): Returns a cache hint (0.3KB) instead of re-fetching (48KB+). Model proceeds to ctx_search.
Stale (>24h): Re-fetches silently. No user action needed.
force: true: Bypasses cache and re-fetches regardless of TTL.
14-day cleanup: Content databases and sources older than 14 days are removed on startup.

This means --continue sessions preserve indexed docs across restarts. No re-fetching, no wasted context tokens.

ctx_stats reports cache performance separately: hits, data avoided, network requests saved, and total context savings including cache.

Progressive Throttling

Calls 1-3: Normal results (2 per query)
Calls 4-8: Reduced results (1 per query) + warning
Calls 9+: Blocked — redirects to ctx_batch_execute

Session Continuity

When the context window fills up, the agent compacts the conversation — dropping older messages to make room. Without session tracking, the model forgets which files it was editing, what tasks are in progress, what errors were resolved, and what you last asked for.

Context Mode captures every meaningful event during your session and persists them in a per-project SQLite database. When the conversation compacts (or you resume with --continue), your working state is rebuilt automatically — the model continues from your last prompt without asking you to repeat anything.

Session continuity requires 4 hooks working together:

| Hook | Role | Claude Code | Gemini CLI | VS Code Copilot | Cursor | OpenCode | KiloCode | OpenClaw | Codex CLI | Antigravity | Kiro | Zed | Pi | |---|---|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:| | PreToolUse | Enforces sandbox routing before tool execution | Yes | -- | -- | Yes | -- | -- | -- | Yes | -- | Yes | -- | ✓ (via tool_call event) | | PostToolUse | Captures events after each tool call | Yes | Yes | Yes | Yes | Plugin | Plugin | Plugin | Yes | -- | Yes | -- | ✓ (via tool_result event) | | UserPromptSubmit | Captures user decisions and corrections | Yes | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | | PreCompact | Builds snapshot before compaction | Yes | Yes | Yes | -- | Plugin | Plugin | Plugin | -- | -- | -- | -- | ✓ (via session_before_compact) | | SessionStart | Restores state after compaction or resume | Yes | Yes | Yes | -- | -- | -- | Plugin | Yes | -- | -- | -- | ✓ (via session_start event) | | | Session completeness | Full | High | High | Partial | High | High | High | Partial | -- | Partial | -- | High |

Note: Full session continuity (capture + snapshot + restore) works on Claude Code, Gemini CLI, and VS Code Copilot. OpenCode provides high session continuity: it captures tool events and injects compaction snapshots via the plugin, but SessionStart is not yet available (#14808), so startup/resume restore is not supported. KiloCode shares the same plugin architecture as OpenCode via the OpenCodeAdapter, so its continuity level depends on KiloCode's SessionStart support. Cursor captures tool events via preToolUse/postToolUse, but sessionStart is currently rejected by Cursor's validator (forum report), so session restore after compaction is not available yet. OpenClaw uses native gateway plugin hooks (api.on()) for full session continuity. Pi Coding Agent provides high session continuity via extension hooks (tool_call, tool_result, session_start, and session_before_compact). Codex CLI has MCP tools today, but hook-based session tracking is pending upstream dispatch (codex_hooks Stage::UnderDevelopment, openai/codex#16685). Kiro has pre/post tool hooks but no SessionStart/agentSpawn restore. Antigravity and Zed have no hook support, so session tracking is not available there.

Every tool call passes through hooks that extract structured events:

| Category | Events | Priority | Captured By | |---|---|---|---| | Files | read, edit, write, glob, grep | Critical (P1) | PostToolUse | | Tasks | create, update, complete | Critical (P1) | PostToolUse | | Rules | CLAUDE.md / GEMINI.md / AGENTS.md paths + content | Critical (P1) | SessionStart | | Decisions | User corrections, preferences ("use X instead", "don't do Y") | High (P2) | UserPromptSubmit | | Git | checkout, commit, merge, rebase, stash, push, pull, diff, status | High (P2) | PostToolUse | | Errors | Tool failures, non-zero exit codes | High (P2) | PostToolUse | | Environment | cwd changes, venv, nvm, conda, package installs | High (P2) | PostToolUse | | MCP Tools | All mcp__* tool calls with usage counts | Normal (P3) | PostToolUse | | Subagents | Agent tool invocations | Normal (P3) | PostToolUse | | Skills | Slash command invocations | Normal (P3) | PostToolUse | | Role | Persona / behavioral directives ("act as senior engineer") | Normal (P3) | UserPromptSubmit | | Intent | Session mode classification (investigate, implement, debug) | Low (P4) | UserPromptSubmit | | Data | Large user-pasted data references (>1 KB) | Low (P4) | UserPromptSubmit | | User Prompts | Every user message (for last-prompt restore) | Critical (P1) | UserPromptSubmit |

PreCompact fires
  → Read all session events from SQLite
  → Build priority-tiered XML snapshot (≤2 KB)
  → Store snapshot in session_resume table

SessionStart fires (source: "compact")
  → Retrieve stored snapshot
  → Write structured events file → auto-indexed into FTS5
  → Build Session Guide with 15 categories
  → Inject <session_knowledge> directive into context
  → Model continues from last user prompt with full working state

The snapshot is built in priority tiers — if the 2 KB budget is tight, lower-priority events (intent, MCP tool counts) are dropped first while critical state (active files, tasks, rules, decisions) is always preserved.

After compaction, the model receives a Session Guide — a structured narrative with actionable sections:

Last Request — user's last prompt, so the model continues without asking "what were we doing?"
Tasks — checkbox format with completion status ([x] completed, [ ] pending)
Key Decisions — user corrections and preferences ("use X instead", "don't do Y")
Files Modified — all files touched during the session
Unresolved Errors — errors that haven't been fixed
Git — operations performed (checkout, commit, push, status)
Project Rules — CLAUDE.md / GEMINI.md / AGENTS.md paths
MCP Tools Used — tool names with call counts
Subagent Tasks — delegated work summaries
Skills Used — slash commands invoked
Environment — working directory, env variables
Data References — large data pasted during the session
Session Intent — mode classification (implement, investigate, review, discuss)
User Role — behavioral directives set during the session

Detailed event data is also indexed into FTS5 for on-demand retrieval via search().

Claude Code — Full session support. All 5 hook types fire, capturing tool events, user decisions, building compaction snapshots, and restoring state after compaction or --continue.

Gemini CLI — High coverage. PostToolUse (AfterTool), PreCompact (PreCompress), and SessionStart all fire. Missing UserPromptSubmit, so user decisions and corrections aren't captured — but file edits, git ops, errors, and tasks are fully tracked.

VS Code Copilot — High coverage. Same as Gemini CLI — PostToolUse, PreCompact, and SessionStart all fire. User decisions aren't captured but all tool-level events are.

Cursor — Partial coverage. Native preToolUse and postToolUse hooks capture tool events. sessionStart is documented by Cursor but currently rejected by their validator, so session restore is not available. Routing instructions are delivered via MCP server startup instead.

OpenCode — Partial. The TypeScript plugin captures PostToolUse events via tool.execute.after, but SessionStart is not yet available (#14808). Events are stored but not automatically restored after compaction.

KiloCode — Partial. Shares the same plugin architecture as OpenCode via the OpenCodeAdapter. The TypeScript plugin captures PostToolUse events via tool.execute.after, but SessionStart availability depends on KiloCode's implementation. Events are stored but may not be automatically restored after compaction.

OpenClaw / Pi Agent — High coverage. All tool lifecycle hooks (after_tool_call, before_compaction, session_start) fire via the native gateway plugin. User decisions aren't captured but file edits, git ops, errors, and tasks are fully tracked. Falls back to DB snapshot reconstruction if compaction hooks fail on older gateway versions. See docs/adapters/openclaw.md.

Codex CLI — MCP active, hooks ready. Hook scripts (PreToolUse, PostToolUse, SessionStart) are implemented and tested but Codex CLI doesn't dispatch them yet (Stage::UnderDevelopment). MCP tools work. Track: openai/codex#16685.

Antigravity — No session support. No hooks, no event capture. Requires manually copying GEMINI.md to your project root. Auto-detected via MCP protocol handshake (clientInfo.name).

Zed — No session support. No hooks, no event capture. Requires manually copying AGENTS.md to your project root. Auto-detected via MCP protocol handshake (clientInfo.name).

Kiro — Partial coverage. Native preToolUse and postToolUse hooks capture tool events and enforce sandbox routing. agentSpawn (the Kiro equivalent of SessionStart) is not yet implemented, so session restore after compaction is not available. Requires manually copying KIRO.md to your project root. Auto-detected via MCP protocol handshake (clientInfo.name).

Pi Coding Agent — High coverage. The extension registers all key lifecycle events: tool_call (PreToolUse), tool_result (PostToolUse), session_start (SessionStart), and session_before_compact (PreCompact). File edits, git ops, errors, and tasks are fully tracked. Session restore after compaction works via the extension's event hooks.

Platform Compatibility

| Feature | Claude Code | Gemini CLI | VS Code Copilot | Cursor | OpenCode | KiloCode | OpenClaw | Codex CLI | Antigravity | Kiro | Zed | Pi | |---|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:| | MCP Server | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | | PreToolUse Hook | Yes | Yes | Yes | Yes | Plugin | Plugin | Plugin | Pending | -- | Yes | -- | Yes (extension) | | PostToolUse Hook | Yes | Yes | Yes | Yes | Plugin | Plugin | Plugin | Pending | -- | Yes | -- | Yes (extension) | | SessionStart Hook | Yes | Yes | Yes | -- | -- | -- | Plugin | Pending | -- | -- | -- | Yes (extension) | | PreCompact Hook | Yes | Yes | Yes | -- | Plugin | Plugin | Plugin | -- | -- | -- | -- | Yes (extension) | | Can Modify Args | Yes | Yes | Yes | Yes | Plugin | Plugin | Plugin | Pending | -- | -- | -- | Yes (extension) | | Can Block Tools | Yes | Yes | Yes | Yes | Plugin | Plugin | Plugin | Pending | -- | Yes | -- | Yes (extension) | | Utility Commands (ctx) | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes (/ctx-stats, /ctx-doctor) | | Slash Commands | Yes | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | | Plugin Marketplace | Yes | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |

OpenCode uses a TypeScript plugin paradigm — hooks run as in-process functions via tool.execute.before, tool.execute.after, and experimental.session.compacting, providing the same routing enforcement and session continuity as shell-based hooks. SessionStart is not yet available (#14808), but compaction recovery works via the plugin's compacting hook.
KiloCode shares the same TypeScript plugin architecture as OpenCode via the OpenCodeAdapter, with platform-specific configuration paths (kilo.json instead of opencode.json, ~/.config/kilo/ instead of ~/.config/opencode/). Hook capabilities depend on KiloCode's implementation of the plugin interface.
OpenClaw runs context-mode as a native gateway plugin targeting Pi Agent sessions. Hooks register via api.on() (tool/lifecycle) and api.registerHook() (commands). All tool interception and compaction hooks are supported. See docs/adapters/openclaw.md.
Codex CLI has MCP support today. Hook dispatch is not active in Codex sessions yet (codex_hooks is Stage::UnderDevelopment), so context-mode treats hook behavior as pending and relies on AGENTS.md routing instructions until upstream dispatch lands (openai/codex#16685). Antigravity and Zed do not support hooks. They rely solely on manually-copied routing instruction files (AGENTS.md / GEMINI.md) for enforcement (~60% compliance). See each platform's install section for copy instructions. Antigravity and Zed are auto-detected via MCP protocol handshake — no manual platform configuration needed.
Kiro supports native preToolUse and postToolUse hooks for routing enforcement and tool event capture. agentSpawn (SessionStart equivalent) and stop are not yet wired. Requires manually copying KIRO.md to your project root. Kiro is auto-detected via MCP protocol handshake (clientInfo.name).
Pi Coding Agent runs context-mode as an extension with full hook support. The extension registers tool_call, tool_result, session_start, and session_before_compact events, providing high session continuity coverage. The MCP server provides the 6 sandbox tools.

Routing Enforcement

Hooks intercept tool calls programmatically — they can block dangerous commands and redirect them to the sandbox before execution. Instruction files guide the model via prompt instructions but cannot block anything. Always enable hooks where supported.

Note: Routing instruction files were previously auto-written to project directories on first session start. This was disabled to prevent git tree pollution (#158, #164). Hook-capable platforms (Claude Code, Gemini CLI, VS Code Copilot, Cursor, OpenCode, OpenClaw, Kiro, Pi) can enforce routing via hooks or plugins. Codex CLI, Antigravity, and Zed require routing instruction files until hook support is available.

| Platform | Hooks | Instruction File | With Hooks | Without Hooks | |---|:---:|---|:---:|:---:| | Claude Code | Yes (auto) | CLAUDE.md | ~98% saved | ~60% saved | | Gemini CLI | Yes | GEMINI.md | ~98% saved | ~60% saved | | VS Code Copilot | Yes | copilot-instructions.md | ~98% saved | ~60% saved | | Cursor | Yes | context-mode.mdc | ~98% saved | ~60% saved | | OpenCode | Plugin | AGENTS.md | ~98% saved | ~60% saved | | OpenClaw | Plugin | AGENTS.md | ~98% saved | ~60% saved | | Codex CLI | Pending | AGENTS.md | -- | ~60% saved | | Antigravity | -- | GEMINI.md | -- | ~60% saved | | Kiro | Yes | KIRO.md | ~98% saved | ~60% saved | | Zed | -- | AGENTS.md | -- | ~60% saved | | Pi | ✓ | AGENTS.md | ~98% saved | ~60% saved |

Without hooks, one unrouted curl or Playwright snapshot can dump 56 KB into context — wiping out an entire session's worth of savings.

See docs/platform-support.md for the full capability comparison.

Utility Commands

Inside any AI session — just type the command. The LLM calls the MCP tool automatically:

ctx stats       → context savings, call counts, session report
ctx doctor      → diagnose runtimes, hooks, FTS5, versions
ctx upgrade     → update from GitHub, rebuild, reconfigure hooks
ctx purge       → permanently delete all indexed content from the knowledge base
ctx insight     → personal analytics dashboard (opens local web UI)

From your terminal — run directly without an AI session:

context-mode doctor
context-mode upgrade
context-mode insight          # opens analytics dashboard in browser
bash scripts/ctx-debug.sh    # full diagnostic report for bug reports

The debug script collects OS info, runtime versions, better-sqlite3 status, adapter detection, config files (redacted), hook validation, FTS5/SQLite test, executor test, process check, session databases, and environment variables into a single pasteable markdown report.

Works on all platforms. On Claude Code, slash commands (/ctx-stats, /ctx-doctor, /ctx-upgrade, /ctx-purge, /ctx-insight) are also available.

Benchmarks

| Scenario | Raw | Context | Saved | |---|---|---|---| | Playwright snapshot | 56.2 KB | 299 B | 99% | | GitHub Issues (20) | 58.9 KB | 1.1 KB | 98% | | Access log (500 requests) | 45.1 KB | 155 B | 100% | | Context7 React docs | 5.9 KB | 261 B | 96% | | Analytics CSV (500 rows) | 85.5 KB | 222 B | 100% | | Git log (153 commits) | 11.6 KB | 107 B | 99% | | Test output (30 suites) | 6.0 KB | 337 B | 95% |

Over the structured-output benchmark subtotal: 315 KB of raw output becomes 5.5 KB. Full-session impact depends on which tools route through context-mode and which platforms have active hooks.

Full benchmark data with 21 scenarios →

Try It

These prompts work out of the box. Run /context-mode:ctx-stats after each to see the savings.

Deep repo research — use batch execution plus indexed search to keep large intermediate outputs out of the chat

Research https://github.com/modelcontextprotocol/servers — architecture, tech stack,
top contributors, open issues, and recent activity. Then run /context-mode:ctx-stats.

Git history analysis — 1 call, 5.6 KB context

Clone https://github.com/facebook/react and analyze the last 500 commits:
top contributors, commit frequency by month, and most changed files.
Then run /context-mode:ctx-stats.

Web scraping — 1 call, 3.2 KB context

Fetch the Hacker News front page, extract all posts with titles, scores,
and domains. Group by domain. Then run /context-mode:ctx-stats.

Large JSON API — 7.5 MB raw → 0.9 KB context (99% saved)

Create a local server that returns a 7.5 MB JSON with 20,000 records and a secret
hidden at index 13000. Fetch the endpoint, find the hidden record, and show me
exactly what's in it. Then run /context-mode:ctx-stats.

Documentation search — 2 calls, 1.8 KB context

Fetch the React useEffect docs, index them, and find the cleanup pattern
with code examples. Then run /context-mode:ctx-stats.

Session continuity — compaction recovery with full state

Start a multi-step task: "Create a REST API with Express — add routes, tests,
and error handling." After 20+ tool calls, type: ctx stats to see the session
event count. When context compacts, the model continues from your last prompt
with tasks, files, and decisions intact — no re-prompting needed.

Privacy & Architecture

Context Mode is not a CLI output filter or a cloud analytics dashboard. It operates at the MCP protocol layer — raw data stays in a sandboxed subprocess and never enters your context window. Web pages, API responses, file analysis, Playwright snapshots, log files — everything is processed in complete isolation.

No telemetry or cloud sync. Your code, prompts, indexed content, and session data are stored locally in SQLite databases under your home directory. The MCP server does not make background network calls by default; explicit user actions such as ctx_fetch_and_index, ctx_upgrade, ctx_insight dependency installation, or setting CONTEXT_MODE_CHECK_LATEST=1 can still access the network.

This is a deliberate architectural choice, not a missing feature. Context optimization should happen at the source, not in a dashboard behind a per-seat subscription. Privacy-first is our philosophy — and every design decision follows from it. License →

Security

Context Mode enforces deny rules from the same permission format you already use and extends those deny checks to the MCP sandbox. If you block sudo, it is also denied inside ctx_execute, ctx_execute_file, and ctx_batch_execute.

Zero setup required. If you haven't configured any permissions, nothing changes. This only activates when you add rules.

{
  "permissions": {
    "deny": [
      "Bash(sudo *)",
      "Bash(rm -rf /*)",
      "Read(.env)",
      "Read(**/.env*)"
    ],
    "allow": [
      "Bash(git:*)",
      "Bash(npm:*)"
    ]
  }
}

Add this to your project's .claude/settings.json (or ~/.claude/settings.json for global rules). All platforms read security policies from Claude Code's settings format — even on Gemini CLI, VS Code Copilot, and OpenCode. Codex CLI security enforcement requires the codex_hooks feature flag to be enabled.

The pattern is Tool(what to match) where * means "anything".

Commands chained with &&, ;, or | are split — each part is checked separately. echo hello && sudo rm -rf /tmp is blocked because the sudo part matches the deny rule.

deny always wins over allow. More specific (project-level) rules override global ones.

Contributing

See CONTRIBUTING.md for the development workflow and TDD guidelines.

git clone https://github.com/mksglu/context-mode.git
cd context-mode && npm install && npm test

License

Licensed under Elastic License 2.0 (source-available). You can use it, fork it, modify it, and distribute it. Two things you can't do: offer it as a hosted/managed service, or remove the licensing notices. We chose ELv2 over MIT because MIT permits repackaging the code as a competing closed-source SaaS — ELv2 prevents that while keeping the source available to everyone.

Published

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Readme

Context Mode

The Problem

Install

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How the Sandbox Works

How the Knowledge Base Works

Ranking: Reciprocal Rank Fusion

Proximity Reranking

Fuzzy Correction

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Progressive Throttling

Session Continuity

Platform Compatibility

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Utility Commands

Benchmarks

Try It

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