nulm 0.1.4

Local-first MCP agent quality and execution layer with guarded local tools

Nulm

CI: GitHub Actions | PyPI package: nulm | CLI: nulm | Python: 3.10+ | License: MIT | Code style: Black

Nulm wraps your MCP client with path-safe file operations, guarded shell execution, and audit logging without requiring a remote server.

Nulm is a lightweight Python MCP server for developers who want an AI client to work inside a local project without handing it unrestricted filesystem or shell access. It lets the client inspect files, apply controlled patches, run guarded commands, search/index source code, and leave an audit trail for what happened.

Today the reliable core is the local MCP execution substrate: guarded file access, guarded shell execution, patch application, audit logging, policy checks, and MCP client setup. The agent-quality features are early advisory tools layered on top of that core. They can help shape requests, plans, and reviews, but they do not replace code review, tests, approvals, or the built-in guard policy.

Security Model

Nulm starts fail-closed by default. Mutating tools and shell tools require either client-managed approval or trusted local auto-approval (CLAUDE_BRIDGE_AUTO_APPROVE=1).

• Local-only by design: no remote service needed for core operation
• Path boundaries: tools resolve paths against configured project root and allowed roots
• Command filtering: sudo, rm -rf, chmod 777, | bash, curl | node, node -e blocked
• Path traversal protection: ../ cannot escape configured roots
• Sensitive file protection: .env, .pem, .key, id_rsa blocked from reads/writes/patches
• Symlink hardening: copy/move operations reject symlink attacks
• TOCTOU protection: writes use O_CREAT | O_EXCL and pre-write symlink checks
• Atomic writes: temp file then os.replace to prevent partial writes
• ReDoS protection: regex compilation has 2-second timeout
• Audit logging: structured, masked audit records with replay capability

See docs/security-model.md for the full rule-writing guide.

Naming Note

Surface	Use
PyPI package	nulm
CLI command	nulm
Compatibility CLI alias	claude-bridge
Python module	claude_bridge
Config/env prefix	CLAUDE_BRIDGE_*

The project was originally named claude-bridge. Public packaging now uses nulm, while the Python module, config directory, and environment variables keep the old names for backward compatibility during the alpha cycle.

Quick Start

pipx install "nulm[recommended]"
nulm init
nulm install

Runs an interactive setup — choose detailed or simple, AI provider, approval mode, and more. Restart Claude Desktop and start a new conversation.

The recommended extra is the easiest path for normal IDE/Desktop use: core file tools, guarded shell, URL reading, PDF/image reading, token helpers, and Tree-sitter indexing. You do not need Nulm skills for the basic read/list/search/shell/patch workflow.

For quick setup with defaults:

nulm install --simple

For other MCP clients:

nulm install --target vscode
nulm install --target generic-stdio

Example: Safe Refactor in Claude Desktop

Install Nulm for a local Python project:

nulm install --target claude-desktop --project-dir ~/myproject

Then fully quit and reopen Claude Desktop, start a new conversation, and ask:

Use Nulm to inspect myproject/auth.py and fix any SQL injection risk you find.

Nulm keeps the work inside the configured project roots, requires approval for mutating tools and shell commands unless you opt into local auto-approval, and records structured audit entries.

Current Status

Core

• File operations: read_file, read_multiple_files, list_directory, write_file, move_file, copy_path, search_in_files
• Targeted edits: patch_file, preview_patch with SEARCH/REPLACE patches
• Shell execution: run_shell through a guarded shell=False execution path
• Common readers: read_url, read_pdf, and read_image are in the default standard profile; PDF/image readers need nulm[recommended] or nulm[multi-format]
• Code indexing: index_codebase, find_relevant_files — symbolic source index and relevance ranking without embeddings
• Workflow helpers: run_workflow, run_agent_loop_step, run_agent_loop_session — structured review, explain, test, todo, quality, and bounded agent-loop flows
• Feature routing for IDEs: nulm_assist maps natural-language requests for AI Council, AI Evaluator, Guard Policy, plan review, result review, setup, and token use to the right tools
• AI Council: run_council_session is available in the explicit full profile as a read-only multi-role planning debate
• Full-profile Git commit helper: commit_changes for explicit local commits
• Audit logging: tool calls recorded as structured JSONL
• Policy engine: custom guard rules, team RBAC, deterministic policy replay, policy diff for CI/CD
• Replay and appeal: deterministic decision replay and post-hoc appeal with audit chain
• Tool profiles: essential, standard, full for token/capability tradeoffs
• Local control plane: task and approval state exposed through CLI, MCP tools, and a localhost-only dashboard
• Multi-root workspace switching: workspace_status and switch_project_root for working across multiple project roots with path boundary enforcement

Optional Extras

These require installing extras such as nulm[recommended], nulm[treesitter], nulm[multi-format], or nulm[smart].

• Tree-sitter indexing: optional parser-backed indexing for supported languages
• Multi-format readers: read_image, read_pdf, read_url with optional image/PDF dependencies and constrained text-only HTTP/HTTPS reading
• Token-aware helpers: optional token estimation and context-sizing helpers
• Encrypted local memory: optional cryptography-backed local memory support
• YAML policy files: optional YAML parsing for guard policy files

Planned / Experimental

• Bridge-internal AI routing: optional model profiles and keyword/task rules choose providers for Bridge advisory calls while keeping API keys in environment variables.
• Adaptive proposals: list_pending_proposals, get_proposal_details, accept_proposal, and reject_proposal expose advisory recommendations and record user decisions. Proposals are inert until accepted.
• Anomaly detection: rule-based audit anomaly scanning. Scores are surfaced for review; they do not silently change policy decisions.
• Full-profile meta-agent tools: local plans, approach exploration, deterministic self-critique, and git-backed checkpoints.
• Full-profile proposal tools: adaptive proposal review stays out of the default tool profile until its workflow is clearer.
• Agent Quality tools: deterministic prompt improvement, context strategy, plan critique, safe config suggestions, workflow quality gates, result quality review, and fail-safe provider advice parsing telemetry.
• Integration plumbing: Redis cache, Prometheus metrics, OpenTelemetry tracing, and SSE helpers are packaged for integration work, but are not required for the normal MCP server path.

Installation

pipx install "nulm[recommended]"
nulm install         # interactive setup
nulm install --simple # quick setup with defaults

nulm is the installed CLI command. The package name is nulm. The older claude-bridge command remains as a compatibility alias for this alpha cycle.

Optional extras are available when installing from an environment that supports extras:

pip install "nulm[recommended]"  # practical local IDE/Desktop feature set
pip install "nulm[treesitter]"    # optional Tree-sitter indexing
pip install "nulm[multi-format]"  # optional image/PDF reading
pip install "nulm[smart]"         # token-aware helpers
pip install "nulm[memory]"        # encrypted local memory support
pip install "nulm[policy-yaml]"   # YAML policy files
pip install "nulm[redis]"         # experimental Redis-backed cache plumbing
pip install "nulm[observability]" # experimental Prometheus metrics plumbing
pip install "nulm[tracing]"       # experimental OpenTelemetry tracing plumbing
pip install "nulm[streaming]"     # experimental SSE streaming helpers

The recommended extra bundles the practical user-facing extras for most local installs. Redis, observability, tracing, streaming, encrypted memory, and legacy FastAPI/Uvicorn support are packaged for integration work, but they are not required for the normal MCP server path and should be treated as experimental in this alpha.

See docs/optional-dependencies.md for the full extras matrix.

Add to an MCP client

nulm install can write supported target configs, while nulm setup prints a copy-pasteable snippet:

nulm install --target claude-desktop --project-dir .
nulm setup --target generic-stdio --project-dir .
nulm setup --target vscode --project-dir .

Generic stdio server entry:

{
  "servers": {
    "nulm": {
      "command": "python3",
      "args": ["-m", "claude_bridge.mcp_server"],
      "env": {
        "CLAUDE_BRIDGE_PROJECT_DIR": "/absolute/path/to/project",
        "CLAUDE_BRIDGE_ALLOWED_ROOTS": "/absolute/path/to/project",
        "CLAUDE_BRIDGE_AUTO_APPROVE": "0",
        "CLAUDE_BRIDGE_CLIENT_MANAGED_APPROVAL": "1",
        "CLAUDE_BRIDGE_TOOL_PROFILE": "standard",
        "PYTHONUNBUFFERED": "1"
      }
    }
  }
}

Some clients use a different top-level wrapper than servers; keep the inner nulm entry and adapt the wrapper to the client's MCP configuration format.

Claude Desktop example

nulm install --target claude-desktop --project-dir .

Then fully quit and reopen Claude Desktop, and start a new conversation.

Approval Model

Nulm starts fail-closed by default. Mutating tools and shell tools require either client-managed approval or trusted local auto-approval (CLAUDE_BRIDGE_AUTO_APPROVE=1).

For Claude Desktop approval UI support: nulm setup --client-managed-approval ....

With CLAUDE_BRIDGE_CLIENT_MANAGED_APPROVAL=1, Nulm assumes the MCP client shows approval prompts. If the client does not enforce approvals, mutating tools may proceed without a local prompt.

Known limitations (v0.1.4)

• Nulm is a policy-gated local runner, not an OS or container sandbox.
• Shell velocity rate limits are configured via env vars but not yet enforced at runtime.
• Audit HMAC uses a development default key unless CLAUDE_BRIDGE_AUDIT_KEY is set.
• The experimental secret_store module is not on the default MCP path; local storage is plaintext JSON.
• Invalid JSON in CLAUDE_BRIDGE_*_JSON env vars is ignored with a warning logged to stderr.

See docs/security-model.md for the full security model.

Workflow Modes

run_workflow supports: review, optimize, orchestrate, agent_loop, quality, test, todo, explain, commit. Prompt shortcuts (/review, /optimize, etc.) are also registered.

With execute=true, workflows run a safe read-only discovery step (file reads and listing only, no shell or patch execution).

AI Council and Model Routing

The council workflow is read-only. It runs a bounded set of role-based planning prompts, synthesizes the responses, lists risks, and returns steps_json that can be applied through the existing plan/approval tools. It does not patch files, run shell commands, or override policy.

/council target="src/" task="add model routing"

Equivalent MCP tool call:

run_council_session(task="add model routing", target="src/", agent_count=5, rounds=2)

Bridge-internal AI routing is disabled by default. When enabled, it affects only Bridge advisory calls such as the council workflow; it cannot switch the MCP client's main chat model.

export CLAUDE_BRIDGE_AI_ROUTING_ENABLED=1
export CLAUDE_BRIDGE_AI_ROUTING_MODE=auto
export CLAUDE_BRIDGE_AI_DEFAULT_PROFILE=local
export CLAUDE_BRIDGE_AI_PROFILES_JSON='{
  "fast": {
    "provider": "openai",
    "model": "gpt-4o-mini",
    "api_key_env": "OPENAI_API_KEY",
    "quality_tier": "cheap",
    "input_cost_per_mtok": 0.15,
    "output_cost_per_mtok": 0.60,
    "max_output_tokens": 400
  },
  "deep": {
    "provider": "anthropic",
    "model": "claude-3-5-sonnet-latest",
    "api_key_env": "ANTHROPIC_API_KEY",
    "quality_tier": "deep",
    "input_cost_per_mtok": 3.0,
    "output_cost_per_mtok": 15.0,
    "max_output_tokens": 1000
  }
}'
export CLAUDE_BRIDGE_AI_ROUTING_RULES_JSON='[
  {"name": "security", "profile": "deep", "keywords": ["security", "secret", "approval"]}
]'

Route decisions include the selected profile, provider, quality tier, estimated input tokens, effective output-token cap, and estimated maximum cost. Cost values are estimates from configured profile metadata and are meant for transparency, not billing reconciliation.

Provider API keys must be supplied through named environment variables, such as OPENAI_API_KEY, ANTHROPIC_API_KEY, DEEPSEEK_API_KEY, MINIMAX_API_KEY, GEMINI_API_KEY, GROQ_API_KEY, MISTRAL_API_KEY, COHERE_API_KEY, XAI_API_KEY, TOGETHER_API_KEY, OPENROUTER_API_KEY, PERPLEXITY_API_KEY, and FIREWORKS_API_KEY. Raw keys are not stored in Bridge config or returned by get_config. Custom cloud provider base_url values must use HTTPS and must not point to private/internal hosts; Ollama routing is limited to localhost/loopback URLs.

Adaptive Proposals

The adaptive proposal layer stores approval-gated recommendations under .claude-bridge/proposals. Proposals are inert until explicitly accepted with accept_proposal; accepting or rejecting a proposal records the user's decision, but does not directly disable or mutate skills.

MCP peer discovery is metadata-only. It can identify nearby MCP-like processes and filter already-known tool schemas, but it does not launch peer commands, run package-manager probes, or execute discovered MCP tools. High-risk or invalid schemas are filtered out of recommendations.

Agent Quality examples

The current Agent Quality Layer is deterministic and advisory by default. It can clarify rough requests, critique plans, suggest context/token strategy, expose quality-first workflow gates, and review result quality. Provider-backed advice parsing has a strict local fail-safe contract, but this layer does not make network provider calls by itself. It does not replace approvals, hard denies, or local configuration rules.

See docs/agent-quality-chat-flows.md for non-expert chat flows such as public readiness, professionalizing code, reducing token use, fixing bugs, and checking whether completed work is good enough.

Skill governance is documented in docs/skill-discovery.md. V1 skill discovery is local-first: packages can be inspected before import, recommendations are explained, and remote auto-download/install/run is intentionally out of scope.

The repository-root skills/ directory contains development/example skill specs and helpers. It is not packaged as runtime user skills in the PyPI distribution; user-imported skills are handled through the documented local skill registry.

Local Control Plane

When the machine is already running a long MCP task, Nulm can keep local task and approval state under ~/.claude-bridge/control-plane. You can inspect or intervene from another terminal:

nulm tasks list
nulm tasks cancel latest --reason "Heading out"
nulm approvals list --status pending
nulm approvals approve latest

For a browser view on the same computer:

nulm dashboard

For phone access on the same trusted Wi-Fi:

nulm dashboard --lan

For safer remote access, put the phone and computer on the same Tailscale network and bind only to the VPN address:

nulm dashboard --vpn

For temporary convenience when VPN is not available, start an explicit Cloudflare tunnel:

nulm dashboard --public

The dashboard binds to 127.0.0.1 by default, uses a per-session token in the URL, and can list tasks, list approvals, run guarded nulm ... CLI commands, cancel tasks, approve actions, and reject actions without requiring a hosted server. LAN, VPN, and public modes print a tokenized URL and keep the dashboard API token out of the static browser config. Prefer --vpn for remote access. Use --public only briefly; anyone who has the URL can control the local dashboard while the tunnel process is running.

Feature Evaluation

Nulm should not keep features just for show. Each feature should have a clear local-first job and an honest current status:

• Keep features that are implemented, useful, documented, and covered by focused tests.
• Rework features that point in the right direction but need clearer behavior, names, or boundaries.
• Hide experimental or niche surfaces from default profiles when they add confusion or token cost before they are broadly useful.
• Remove features that are mostly decorative, duplicate better paths, or cannot be made safe and explainable.

The product direction is a local control plane and quality layer for MCP-based development. Docs should distinguish implemented CLI/MCP behavior from planned control-plane ideas, and should not imply remote monitoring or hosted sync unless code for that surface is added.

Custom Policy

Add .claude-bridge-guard.json to the project root to customize the guard layer. Supports blocked_shell_patterns, sensitive_path_patterns, secret_patterns, and ordered rules with conditions (tool, field_equals, regex, glob, extension, etc.).

nulm policy validate --path .claude-bridge-guard.json
nulm policy simulate \
  --path .claude-bridge-guard.json \
  --tool run_shell \
  --param command="npm test"

See docs/security-model.md for full rule-writing guide.

Team Policy (RBAC)

Team policies define role-based access controls with inheritance. See docs/security-model.md for the full schema.

nulm policy diff --base .claude-bridge/team.json --head pr/team.json

AI Advisor and Agent Quality Direction

An optional second-opinion layer for proposed agent actions. It can suggest allow, deny, or ask, but its broader role is to critique whether the next step is necessary, scoped, safe, and aligned with the user's intent. It does not override built-in hard denies.

Disabled by default. The local deterministic provider works without network access. Anthropic, OpenAI, Ollama, DeepSeek, MiniMax, Google Gemini, Groq, Mistral, Cohere, xAI, Together AI, OpenRouter, Perplexity, and Fireworks providers are optional and fail closed on invalid responses or provider errors. The current Python module and environment variables still use the ai_evaluator name for backward compatibility.

The current advisor is an early, advisory slice of the larger Agent Quality Layer described in docs/agent-quality-layer-plan.md. The implemented pieces focus on scoped prompts, plan critique, token/context suggestions, safe config suggestions, and result review. bridge_status also exposes Agent Quality telemetry for provider-response parsing and fallback counts so failures stay visible.

export CLAUDE_BRIDGE_AI_EVALUATOR_ENABLED=1
export CLAUDE_BRIDGE_AI_EVALUATOR_PROVIDER=local

Audit, Replay, and Anomaly Detection

nulm audit --last --tool run_shell --decision deny --risk high
nulm replay --record-id <record_id>
nulm anomaly scan --last
nulm appeal --record-id <record_id> --justification "reason"

Anomaly scoring is advisory in v0.1: high scores are surfaced in summaries and audit metadata, but they do not silently change guard-policy decisions. Nulm is a policy-gated local runner, not an OS or container sandbox.

Set CLAUDE_BRIDGE_AUDIT_KEY when audit tamper evidence matters; without it, HMAC signatures use a public development default.

Development

pip install -e .
pip install -e .[dev]
pip install -e .[treesitter]
pip install -e .[multi-format]
nulm doctor --project-dir . security
ruff check .
black --check .
mypy src
pytest

Benchmarking

nulm benchmark --query "login auth" --path src --json

Troubleshooting

Issue	Fix
Claude says it cannot access local files	Ask it to check the Nulm MCP tools and call workspace_status() first; restart or reload the MCP client if tools are missing.
macOS: Operation not permitted	Use /usr/bin/env with the module command in config.
Tools not appearing	Check the client MCP config is valid JSON; verify the Python environment.
Claude Desktop logs	~/Library/Logs/Claude/mcp-server-claude-bridge.log

Requirements

• Python 3.10+
• An MCP client

License

MIT. See LICENSE.

Contributing

Contributions are welcome. Please open an issue before larger changes.

This project is not an official Anthropic product.