lean-ctx

name	lean-ctx
description	Context Runtime for AI Agents — 46 MCP tools, 10 read modes, 90+ shell patterns, tree-sitter AST for 18 languages. Compresses LLM context by up to 99%. Use when reading files, running shell commands, searching code, or exploring directories. Auto-installs if not present.

LeanCTX — Context Runtime for AI Agents

LeanCTX optimizes LLM context through 46 MCP tools, 90+ shell compression patterns, and tree-sitter AST parsing for 18 languages. It provides adaptive file reading, cross-session memory (CCP), task-conditioned relevance scoring, and a feedback loop for learning optimal compression.

Setup (run first)

Before using lean-ctx, verify it is installed:

which lean-ctx || bash scripts/install.sh

If the install script is not available locally, install manually:

curl -fsSL https://raw.githubusercontent.com/yvgude/lean-ctx/main/skills/lean-ctx/scripts/install.sh | bash

After installation, configure the MCP server:

lean-ctx init --global
lean-ctx doctor --fix

When to use lean-ctx

Always prefer lean-ctx -c <command> over running commands directly when:

• The command produces verbose output (build logs, git diffs, dependency trees, test results)
• You are reading files and only need the structure or API surface
• You want to check token savings for the current session

Shell commands (use instead of raw exec)

lean-ctx -c git status          # Compressed git output
lean-ctx -c git diff            # Only meaningful diff lines
lean-ctx -c git log --oneline -10
lean-ctx -c npm install         # Strips progress bars, noise
lean-ctx -c cargo build
lean-ctx -c cargo test
lean-ctx -c docker ps
lean-ctx -c kubectl get pods
lean-ctx -c aws ec2 describe-instances
lean-ctx -c helm list
lean-ctx -c prisma migrate dev
lean-ctx -c curl -s <url>       # JSON schema extraction
lean-ctx -c ls -la <dir>        # Grouped directory listing

Supported: git, npm, pnpm, yarn, bun, deno, cargo, docker, kubectl, helm, gh, pip, ruff, go, eslint, prettier, tsc, aws, psql, mysql, prisma, swift, zig, cmake, ansible, composer, mix, bazel, systemd, terraform, make, maven, dotnet, flutter, poetry, rubocop, playwright, curl, wget, and more.

File reading (compressed modes)

lean-ctx read <file>                    # Full content with structured header
lean-ctx read <file> -m map             # Dependency graph + exports + API (~5-15% tokens)
lean-ctx read <file> -m signatures      # Function/class signatures only (~10-20% tokens)
lean-ctx read <file> -m aggressive      # Syntax-stripped (~30-50% tokens)
lean-ctx read <file> -m entropy         # Shannon entropy filtered (~20-40% tokens)
lean-ctx read <file> -m diff            # Only changed lines since last read

Use map mode when you need to understand what a file does without reading every line. Use signatures mode when you need the API surface of a module (tree-sitter for 18 languages). Use full mode only when you will edit the file.

AI Tool Integration

lean-ctx init --global          # Install shell aliases
lean-ctx init --agent claude    # Claude Code PreToolUse hook
lean-ctx init --agent cursor    # Cursor hooks.json
lean-ctx init --agent gemini    # Gemini CLI BeforeTool hook
lean-ctx init --agent codex     # Codex AGENTS.md
lean-ctx init --agent windsurf  # .windsurfrules
lean-ctx init --agent cline     # .clinerules
lean-ctx init --agent crush     # Crush MCP config
lean-ctx init --agent copilot   # VS Code / Copilot .vscode/mcp.json

Multi-Agent & Knowledge (v2.7.0+)

MCP tools:

• ctx_knowledge(action="remember", category, key, value) — persistent cross-session project knowledge store
• ctx_knowledge(action="recall", query) — search stored facts by text or category
• ctx_knowledge(action="consolidate") — extract session findings into permanent knowledge
• ctx_agent(action="register", agent_type, role) — multi-agent context sharing with scratchpad messaging
• ctx_agent(action="post", message, tags) — share findings/warnings between concurrent agents
• ctx_agent(action="read") — read messages from other agents
• ctx_agent(action="handoff", to_agent, message) — transfer task to another agent
• ctx_agent(action="sync") — multi-agent sync status (active agents, pending messages, shared contexts)
• ctx_share(action="push", paths, to_agent, message) — push cached file contexts to another agent
• ctx_share(action="pull") — pull shared contexts from other agents
• ctx_share(action="list") — list all shared contexts
• ctx_share(action="clear") — remove contexts shared by this agent

Additional Intelligence Tools (v2.19.0)

• ctx_edit(path, old_string, new_string) — search-and-replace file editing without native Read/Edit
• ctx_overview(task) — task-relevant project map at session start
• ctx_preload(task) — proactive context loader, caches task-relevant files
• ctx_semantic_search(query) — BM25 code search by meaning across the project
• ctx_intent now supports multi-intent detection and complexity classification
• Semantic cache: TF-IDF + cosine similarity for finding similar files across reads

Session Continuity (CCP)

lean-ctx sessions list          # List all CCP sessions
lean-ctx sessions show          # Show latest session state
lean-ctx wrapped                # Weekly savings report card
lean-ctx wrapped --month        # Monthly savings report card
lean-ctx benchmark run          # Real project benchmark (terminal output)
lean-ctx benchmark run --json   # Machine-readable JSON output
lean-ctx benchmark report       # Shareable Markdown report

MCP tools for CCP:

• ctx_session status — show current session state (~400 tokens)
• ctx_session load — restore previous session (cross-chat memory)
• ctx_session task "description" — set current task
• ctx_session finding "file:line — summary" — record key finding
• ctx_session decision "summary" — record architectural decision
• ctx_session save — force persist session to disk
• ctx_wrapped — generate savings report card in chat

Analytics

lean-ctx gain                   # Visual token savings dashboard
lean-ctx dashboard              # Web dashboard at localhost:3333
lean-ctx session                # Adoption statistics
lean-ctx discover               # Find uncompressed commands in shell history

Tips

• The output suffix [lean-ctx: 5029→197 tok, -96%] shows original vs compressed token count
• For large outputs, lean-ctx automatically truncates while preserving relevant context
• JSON responses from curl/wget are reduced to schema outlines
• Build errors are grouped by type with counts
• Test results show only failures with summary counts
• Cached re-reads cost only ~13 tokens